# The Stax SRM-001 mod thread



## AudioCats

My original posts were buried in the Stax thread. This is the summery of some of the technical info. I will add the output cap test result by the end of next January (have to get those boutique caps first). 

 If you have done mods to your SRM-001 or have mod related info please contribute, some DIY'er might want to mod his/her SR-001 system to the "king of the portable" status.....


 My mods/test will be done in five steps, related info/result will come out after each step is completed:
 --A) General info about SRM-001 mods. This gives some idea what can be done to your little portable amp. (done)
 --B) Opamp rolling. Info and test results of replacing opamps in the SRM-001. (done)
 --C) Output capacitor testing. Different output capacitors can give very different sound, and you will notice it. (coming next spring. caps on order).
 --D) Bias voltage test. Believe it or not, the circuit board has traces for an easy bias level change. We will see if lower bias will yield a super smooth sound for vocal....---- will skip this one due to the experiment in post #13, I will instead go toward modifications for driving SR-X. 
 --E) A tutorial with step by step pictorial instructions of how a full version mod is done. Apparently by then my SRM-001 will have too many extra test features and will be unfit for demenstrating how a general mod is done. I will need a fresh amp to complete the tutorial. So I have one slot open for an "full version (i.e. SuperFatCat) ", mod (8599, BlackGate eletrolytics, sonic/kimber output caps, etc). If you wish to get your SRM-001 modded and don't want to do it yourself, please PM me. The full mod package will be $150, it will also includ a RCA/mini adaptor made with Neutrik connectors and solid silver/teflon wire. Only accepting one amp, preferablely from within the US (for easy shipping). I will perform the mods and take pictures for the tutorial. Here are the conditions: 1)you Must also have a SR-003 and a stax 3XX series amp. 2) you must have a high grade CDP and silver IC's. 3) you will promise to provide a 500+ word feedback/report on how the modded SRS-001 compares to a SR-003/SRM-3XX combo. I know the SRM3xx should win but want to know the details. 
--- update 1-13-08: there won't be a pictorial instructions, instead I will provide three to-do/parts-to-use list. The mod slot is still open, PM me if you are interested. 
 --- update 1-29-08: the mod slot has been taken by Larry the HeadphoneAddict 
	

	
	
		
		

		
			





 We still need reviewer with 003/3xx though, since Larry's amp is a SRM-1 which is too good for the SFC-001 to compete with. He will provide a report on the SFC vs. various $400 portable dynamic systems (phones+amp) 


 Where to find some of the info in this thread:

 *Kevin Gilmore's info on 001's circuit layout (thanks a lot Kevin) -- post #8 (this page)

 *info on battery power-- this post and post#71 (page 8)
 *AC adaptor comparison-- post #23 (page 3)
 *HeadphoneAddict's test of AA battery life on a stock 001 amp -- post #51-#55 (page 6)
 *Heat dissipation of Q15 after SFC or UFC mod -- post #49 (page 5)

 *opamp comparison test -- post #4 (this page)
 *Interconnect to use -- post #40 (page 4)

 *FC output cpacitor comparison test-- post #20 (page 2)
 *FC input capacitor comparison test -- post #42 (page 5)
 *FC to-do list -- post #47 (page 5)

 *SuperFatCat input/output capacitor comparison test -- post #43 (page 5)
 *SuperFatCat mod to-do list -- post #48 (page 5)

 *FatCatUltra input/output capacitor comparison test -- post #44 (page 5)
 *Ultra mod to-do list -- post #48 (page 5)

 *sclee's modification to his amp -- post #29(page 3), #38 (page 4)
 *Borisov's modification to his amp -- post #94 (page 10)
 *SFC mod performed on HeadphoneAddict's 001-- post #74 (page 8).
 *HeadphoneAddict's review on the modded 001 -- post #95 (page 10)
 *catscratch's review on the 001 with SFC++RC mod (Rock/Classic) 

 some battery power info,for truely portable/on-the-go use:
 The stock battery compartment configuration holds two AA Alkaline or NimH in series. There is quite a bit of sonic difference between using batteries and the 4.5V AC adaptor, the adaptor sound a lot sharper and a lot more detailed. If you want that clear sound while on the go (true portable, right?), you can convert the battery compartment from series to parallel configuration, and install two 14500 (AA size) Lithium-ion 3.7v rechargable in paralle. The voltage of lithium ion changes between 4.15V (full) to 3.3V (nearly empty), the 3,7V spec is kind of the average voltage. With two lithium ion in paralle you get 3.7V, 1500mAH~2200mAH (depends on the battery) power, which will give you at least a few hours of great sound (depends on whether you do the other mods and the kind of op-amp you use.). 
 Lithium batteries give the cleanest and most involving sound. This should be the first upgrade you want to consider, if you don't want to try anything thing else. Ultrafires 900mAH 14500's are less than $7 each and the charger is about $15. Get four batteries and one charger, convert the battery bay to parallel, then you will be all set 
	

	
	
		
		

		
		
	


	



 -- update 2-28-08: ****Caution!! *DO NOT BUY the UltraFire protected* 14500 li-ion rechargables, it will NOT fit into the 001's battery bay. After adding the protection circuit board, that battery is about 2mm longer than the standard AA, too long to use (strictly saying, the protected cells, being longer than 50mm, should not be called 14500 any more). The unprotected 14500, on the other hand, is the true AA size so can still be used. If you always use the dedicated charger for recharging and turn the amp off when the sound gets bad, the unprotected batteries should still be safe. Of course, the best and safest way to do it is find a open spot in the amp and add the protection board into the amp itself. **** 
 for more info, see post # 71


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## d-cee

looks good, I might put my SRM-001 under the soldering iron in the future too


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## AudioCats

Mods can be done to four areas: 
 1) input/output capacitor upgrade. 
 --The stock input caps are two 0.15uF poly(ester?) caps and two generic 10uf polarized electrolytics. There isn't much room in the little SRM-001 case to exploit, and the input stage does seem to benefit from large input caps (better bass response), so high grade electrolytic caps should be used. Replacing the stock polyester cap and aluminum electrolytic with polyprop caps and blackgate NX non-polar coupling electrolytic will probably bring 20-40% improvement over the original polyester (?) and aluminum electrolytic. Not sure about the % here since I (still) haven't even order the blackgates yet. There is indeed a difference between polyester and polyprop, with electrostatic transducers you Will hear it, the polyester has certain harshness in treble. 
 --Output capacitors (0.01uF/630VDC) testing is still in progress, I tested 4 different polyprop caps plus the stock poly(ester?) so far, and there is quite some difference in sound among the caps. The best sounding so far is the BC component 0.011uf/630V (MKP 420 series, digi key #BC2240-ND, $0.61 each), followed by Epcos 305vAC X2 series ($0.32 each, good mids, smooth highs, strong bass good texture), then the Panasonic ECWF series ($1.31 each, strong bass, warm mids but treble not impressing) I am ordering some boutique caps such as Auri and kimber and Sonic, will see if these high $$ ($4.5 ~$10 each) fancy caps can do better than the cheap X2 series.

 2) high voltage power supply cap upgrade:
 If you don't hate bass, you must install better/larger high voltage caps. The input cap upgrade will improve mids and treble greatly, but will also make the bass, though now much better defined, sound weaker than before. High voltage caps should be at least 0.3uF (the stock cap was a 0.01uF polyester). These new power caps MUST be as high grade as possible, polyprop is pretty much the only choice. (.47uf polyprop has better over-all sound than 1.5uF Mylar caps. Treble, mids, bass, everything ). Due to the size limit, the X2 series caps are about the only options. I use Epcos 305V X2 caps from digikey. 
 Since I like bass, I will say the high voltage upgrade can improve the SQ by up to 50%.

 3) Opamp power supply upgrade, +/- , 9~12V:
 R33, 34 and 35 need to be shorted. The original purpose of these resistors were probably for creating a Pie filter network so small filter capacitor can be used (stock caps were 10uF/16V). The new op-amps (next step) requires a lot more operating current than the stock JRC062L, if you leave R33/34/35 in the circuit they will drop voltage so much that the new opamps won't work. (most audio grade opamps require 3-5mA per amp, while the 062 only need 0.1mA), How are we gonna make sure the power filtering is still good? simple, you drop the R in the RC circuit, then you increase the C, intall larger capacity caps . High quality miniature 16V caps should be used, the minimum capacity requirement depends on the kind of opamp you use. AD823/NE5532/TL082 will need at least 100uf per side, AD8599 somewhere around 300uf per side, have no idea what the minimum will be for AD825's. The available room inside the case, again, is the limit here, so I suspect you can only pack enough uF inside the SRM-001 for the AD8599's.
---- update, 1-13-08: the uF # was if you are using a AC adaptor, without enough uf you will hear a hum from the adaptor supply. You can increase the capacitor size inside the AC adaptor, but since everybody is using a different wallward I will leave that to you. If you only use pure DC, ie. batteries or an AC wallwart with large reservoir caps inside (need to be at least 1000uF/10V), there will not be a requirement on how large the +/- caps have to be, just install the largest capacity that fits in. Again, quality matters, so whenever possible, use blackgates (the PK series are only $1 each anyway). 
 -- update 1-17-08: It turned out that my Panasonic 4.5v/0.8A wallwart has a lot of ripples, which caused the humm. There is no hum at all when using a Sony 4.5v/500mA wallwart, even when the total cap size for the +/- is only 47uf per side. But still, the +/- cap size affects bass quantity and quality a lot, you want to pack in as many uF as possible. 
 4) op-amp upgrade:
 The SRM-001's design came out 10years ago (1997), so an opamp upgrade makes a lot of sense.....
 --The standard upgrade chip recommandation is the AD8599, being a SOIC dual-opamp it can be soldered directly to the existing pads on the circuit board, very straight forward. 
 --If you have trouble getting the high capacity miniature caps for +/- supply, you can use available smaller capacity caps and low current opamps such as AD823 or NE5532 or TL082. I don't have AD823's to try so I have no idea how they will sound, but should be better than the 082 I supposed?
 -- AD825 shows much better resolution/texturing than the 8599, but it requires more current hense larger filtering capacitor. IF you can somehow pack the required larger capacity +/- supply caps into the case it will be the best solution -- update: see the update above for new cap requirements when using pure DC power.

 For DIY, you can probably get a mid-grade modification done with $35-$40 worth of parts ($3 for high voltage X2 polyprop caps, $8 input caps, $15 opamps, $6 for good miniature 16v caps, and $4 for output polyprop caps), then the parts shipping (from two different places) will cost you another $15-$20, so somewhere around $55 total for your new DIY project, not bad.
---- 1-13-08: this for the FC level mods (fat cat class). 

 below is the test set up, for performence testing when there is no size limit.


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## AudioCats

Each opamp gets at least 20 hours of burn-in before listening for sonic characteristic. They should be fairly stable enough by then, though the 825 did benefited a bit from 30 hours of burn-in. 

 some data about the stock amp: 
 -whole amplifier current draw when using 3.7V lithium batteries: with no op-amp plugged in=220mA; with original JRC062 plugged in = 220mA (wow, the 062 almost consume no power at all).
 -SQ of stock configuration: If you haven't heard the upgraded version, the stock amp sounds pretty good......

 Stock op-amp: JRC062L, very low current requirement (0.2mA per chip), low slew rate=3.5V/uS. The sound is clean, probably more due to the eletrostatic phones than the opamp itself. Sound is not airy, has an emphasize in mids, kind of "transistor radio" sounding when compared to the other better opamps. Now, by itself the 062L sound is not bad at all, it's just the newer/better opamps sound so much better......


 now different chips

 The ancient hot-rod (yes they were in the early 90's 
	

	
	
		
		

		
		
	


	




 : NE5532
 --current draw, whole amp: 400mA
 --much more spacious than the 062L, the sound is very soft, not sharp enough for guitar tracks. It is also mids emphasized (or treble recessed), the mids are realistic, so that is good. Good bass, good ambience. Not very fast though.







 LM4562 (the usual upgrade opamp for 5532): 
 --current draw, whole amp= 500mA
 --The sound is clean, cleaner than the 8599. Not sure why I felt that way, it is either the 4562 is presenting highs better or it is not showing as much little micro details as the 8599. Not as much bass as the 8599, but bass definition is good. Anyway the 4562 is not as fully bodied as the 8599 or the 5532. 







 TL082
 Stock opamps (062L's) are ultra low power yet lower performence version of 082. So it makes sense to see how the "uncompromised" version sounds like. These 082's I got here are the hottest 20V/uS edition.
 -- whole amp current draw is 320mA.
 -- sharper sounding than 5532, much better than the low-current 062L, but like the 062L, the 082 is still mids emphasized. Bass is kind of dry, simply not enough for my taste. The sound is pretty fast, ok for guitar tracks. Vocal not very realistic when comparing to other better chips. The overall impression is: sounds kind of dry and hard (?), maybe there is a mids spike somewhere.








 AD8599 (supposedly very fine sounding and a great compromise of many worlds....)
 --current draw, whole amp= 450mA
 --This chip have received quite some hype/acclaim here, mainly from NelsonVendal. It is indeed very good. The sound is darker, more up-front, intimate, juicy and sensual. Warm and very full bodied sound. Great for acustic guitar, full rounded bass (it can even sound slightly too bassy if you make the "baby-stax-face" when playing bass heavy tracks). good bass texture, good details, good resolution. 
 --All in all a great general purpose replacement chip to use in the SRM-001, but especially good for playing vocal. Not as sharp as I want for playing Rock/electric guitar though. 8599 comes in dual amp SOIC package and will fit right onto the existing SOIC-8 pads on the circuit board, promissing a very very straight forward installation. 







 Modern hot-rods: AD825
 --current draw, whole amp=500mA
 -- when I firt install these chips, they sucked so much juice that the on-board power supply couldn't keep up at high volume. After about 30 hours of burn-in though, things were vastly improved, now I get full bass even at very high sound level (louder than I should be listening at). This is with those two external 640uF extra-low ESR caps though.......
 -- Great sound stage, very spacious sound stage (for in-ear phones at least), much better resolution/finer detail than the 8599, but not as much body. Brighter and more "distant" sounding comparing to the 8599. Great bass, very clean and much better texture than any of the above, though not as much in bass quantity as the 8599's. This will be the chip to use for basically everything, it might be the best replacement chip you can install (there are better chips out there, but the +/- current limitation prevents the usual opamp king such as OPA627 from working in this amp). 
 -- Too bad the 825 are only single amps, fitting them onto the board involves quite a bit of work. But that is why DIY is fun, right? 









 The super fast budget op-amp: AD826
 current draw, whole amp= 510mA
 - wouldn't work, major clipping even at low volume, tried only installing one and the clipping was still there, though not as bad. Simply couldn't get it to work. 






 Opamp selection: You should not use any opamp that demands supply current more than 5mA/amp. The 5.5mA is the about the absolute cut point. AD8599 uses less than 5mA/amp and worked great, AD826 requires 7mA/amp and didn't work (major clipping), while the AD825 and LM4562 both still work ok (5-6mA/amp), though it took the 825's 30hours of burn-in to get there. I didn't get to use my OPA637's (7mA/amp) 
	

	
	
		
		

		
		
	


	




 The 825 is the overall winner in this test, but 8599's are still the #1 recommandtion for the opamp upgrade-- very easy to install and don't require super fancy miniature hi-cap capacitors for power supply. 5532 is actually not too bad, I will place it in the 3rd place. There is still AD823 that can work but I didn't buy any due to the bad rep it has received in this forum. AD823 is a low current requirement chip like the 5532 and TL082, and possibly sound better than either. It is also an easy-to-install dual opamp. Maybe somebody will put a pair into his SRM-001 and tell us how it works out.


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## AudioCats

* How to make your "baby-stax-face": put the earspeakers into your ears, then rotate the wire stem forward until it is almost horizontal pointing forward. you should now have a wider sound stage and the bass should get stronger (at least that is how it happens to me). Now open your mouth and drop your jaw as far as possible, as if you were startled, this will open up the connection between your inner ear and the throat and give you even better bass......Experiment different facial expression and find one that gives you the best sound effect from your earspeakers and that will be your "baby stax expression". Enjoy.


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## webbie64

Thanks for all your excellent work, Audiocats. I look forward very much to your further results in January.

 Thanks also for bringing it out as a seperate thread - makes it much easier to keep track and use the info to upgrade my SR-001 when you have finalised the best combo of mods.

 Work like yours is well appreciated by the electrostatic HeadFi community.


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## krmathis

Excellent work!
 I look forward to the end result. Nicely placed inside the original case, and all.


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## kevin gilmore

For those that might want to see a schematic of what is going
 on here, here is a little something less the power supply.
http://gilmore.chem.northwestern.edu/stxp.gif


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## AudioCats

nice!
 I partially traced the circuit, but didn't realize those are JFETs.....( thought they are BJT transistor to form darlington pairs).
 Now is there a need to match the jfets? or are they supposedly already matched?


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## kevin gilmore

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_nice!
 thought they are BJT transistor to form darlington pairs_

 

nope, not darlington. Top transistor is common base drive.
 Same as grounded grid if it was a tube amp. Only way to
 get that much gain without miller effect killing the frequency
 response.


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## AudioCats

.... deleted the initial comparison impressions. 
 If you remember what it was, well after 4 days of burn-in, the initial comparison impressions still held true. Then why would I delete it, you might ask...... well, I will HAVE TO sell the 005 sometime soon, you see 
	

	
	
		
		

		
		
	


	




.

 Have fun


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## AudioCats

Quote:


  Originally Posted by *kevin gilmore* /img/forum/go_quote.gif 
_nope, not darlington. Top transistor is common base drive.
 Same as grounded grid if it was a tube amp. Only way to
 get that much gain without miller effect killing the frequency
 response._

 

Thanks for the info 
	

	
	
		
		

		
		
	


	




 If it was a tube amp, replacing the three 390K resistor with a proper CCS will improve SQ and gain, right? can it be done here too?


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## AudioCats

Just a little experiment: SRM-001 test setup driving the ESP950........ 






 result: can not play very loud (not as loud as I want). Sound is clean, very soft sounding, and since the volume had to remain low it was not showing some of details very well. But the sound was pleasant. Good bass when the output capacitors were increased to 0.1uF. (With baby stax 0.01uF or 0.1uf output had about the same bass, but this experiment showed that larger output caps can drive larger phones better). 

 The ESP950's driver are about the same size as the Lambda's, so the modded SRM-001 won't have enough juice to push the lambda's either. But the SR-XIII, on the other hand, have much smaller drivers and can be a very different story..... I have a feeling that the little amp will be able to drive the SRX reasonably well (just have to lower the bias to 230v). If we can locate a source of Stax special connectors, it won't be difficult to make adaptors to fit SR-X/3/5 with the little amp.

 Not to mention all them electrect phones that have high sensitivity and don't even require a bias voltage, they should feel right at home teamming with the SRM-001


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## spritzer

The smaller drivers should be fine with the SRM-001 as they have a lot in common with the SR-001/003. I think you need a Gamma Pro...


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## AudioCats

Quote:


  Originally Posted by *spritzer* /img/forum/go_quote.gif 
_The smaller drivers should be fine with the SRM-001 as they have a lot in common with the SR-001/003. I think you need a Gamma Pro... 
	

	
	
		
		

		
		
	


	


_

 

no way dude the Gamma pro's cost a fortune nowadays, I'd much rather get a pair of SR-XIII and recable it to silver and convert the SRM-001 to 230V bias 
	

	
	
		
		

		
		
	


	




 by the way, I suspect the reason the 950's sounded so soft was due to the extra output demand dragged down the high voltage supply voltage, and this supply voltage also provides bias for the phones, so: increased output demand -> lower supply voltage -> lower bias than the normal 550~600V -> softer sound. That won't be a problem for low-bias version though, since the bias voltage will be dropped down to 230V anyway (replace R32 with a 10M resistor, install 0.01uF/630v cap at C19 location, and add two 110V/120V diodes at the "R" location, that should do it)......





_update 1-3-08: just ordered caps (BlackGates, Auri, Sonic I/II) from SonicCrafts. Hopefully they will show up in a couple of weeks. Then I will let them burn in for 10 days straight, then the real comparison test..... the schedule is pretty tight, might not get it done by the end of the month.

 update 1-12-08: Got the caps. SonicCraft shipped the caps out the very next day of my order (1-4-08), super! 
	

	
	
		
		

		
		
	


	




 Highly recommanded vender. 
 Too bad the Auri 0.01uf/600v wouldn't fit, just so slightly too big 
	

	
	
		
		

		
		
	


	




 Good thing I still have the Sonic I and II to use 
	

	
	
		
		

		
		
	


	


_


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## Richter Di

deleted


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## antonyfirst

Hey Richter, I'd like to know more about your tip modding. Can you elaborate? Can we also see some pics of finished work? Thanks


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## webbie64

Quote:


  Originally Posted by *antonyfirst* /img/forum/go_quote.gif 
_Hey Richter, I'd like to know more about your tip modding. Can you elaborate? Can we also see some pics of finished work? Thanks_

 

And, AudioCats, any further conclusions on what mods to complete that can improve SQ while retaining all in the original case?


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## AudioCats

webbie, if you install 8599, everything packs into the Stax case, no question about it. Guarranteed to succeed.

 The AD825 on the other hand, is a little tricky, it requires much larger caps if you use an AC adaptor, can be done but not nearly as straight forward as the 8599 (for pure DC operations, see the updated post #2, the green text contains more info). But to install AD825's you will have to make a SOIC->SIP adaptor anyway, which is a major pain in the axxx (creating a PCB program for an adaptor is easy and I have the eagle lite, I just couldn't bring myself to do it).



 plans:

 I am doing the capacitor burn-in right now. The next step will be the input/output cap test. Then I will provide a list of things to do and parts to use. To-do list only, there won't be a complete pictorial step-by-step tutorial anymore. ( I don't want to encourage first time DIY'er to attemp the mods since there is the 550v voltage present. If you have a little DIY experience you should be able to just look at the to-do list and figure out the details by yourself). 
 Three performence levels, pick one depending on your budget and your signal source quality. 
 1) The Fat Cat -- BlackGate/polyprop as input, 8599, BC component as output, and using larger capacity aluminum electrolytic for +/- power.
 2) The Super Fat Cat -- BlackGate/polyprop input, 8599, Sonic I or Sonic II as output, install BlackGates whereever possible. 
 3) The Fat Cat Ultra -- BlackGates/polyprop input, AD825's on adaptor strip, Auricap as output. Install BlackGates whereever possible.
 (Due to the super revealing nature of the electrostatics, I wouldn't recommand a mod level higher than the Super Fat Cat if you are using MP3 as your source.)


 Anyway, I don't know if you guys have ever read the updated 1st post in this thread, I have one slot open for a SFC (super fat cat) mod.... with conditions attached though 
	

	
	
		
		

		
			





 Have fun


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## AudioCats

FatCat class output cap results: (top to button: BC component MKP , Panasonic ECWF Polyprop, Stax stock poly cap, Epcos MKP). 






 -- The best in the group: BC components, MKP420 series, 0.011uF/630v, digikey # BC2240-ND, $0.61 each.
 The sound: Smooth, no harshness, clear highs, best details so far, good mids, strong bass.

 -- 2n place, Panasonic ECWF metalized polyprop, 0.01uF/630v, digikey # p12109-nd, $1.33 each.
 the sound: good treble, slightly smoother than stock caps; warm mids; Strong bass, but lack definition, the bass is also dryer than the BC.

 -- 3nd place: Epcos X2 series (not shown in the picture above). The digikey # for 0.01uf/630V: 495-2317-nd, $0.32 each.
 The sound:I was using 0.1uF but would expect the 0.01uf have the same sonic charactoristic. Larger capacity gives more bass for larger phones (see the ESP950 experiment), but there is not much difference when pushing the baby stax. Anyway, there is a lot of bass, but mids and treble are very soft. After long burn-in they will get nicer, though still not quite as sharp as the Panasonics. But the X2's bass is not as dry, a little more pleasant to my ears. Over all, it is rated very close to the Panasonics, won in some area and losed in others. If you end up going for the AD823 or TL082 (for power consumption reasons), this will be the cap to use. It may also be used for covering up harsh/cold sources.

 -4th place: stock stax 0.01uf/630v poly(ester?) and Epcos MKP 0.01uf (digikey#495-1326-nd, $0.51 each). These two are rated about the same with the Epcos MKP slightly better than Stax poly. Good clear highs but has some harshness (quite noticable with the stock cap, MKP is a bit smoother); good mids; bass lacks both definition and strength. 

 Above polyprops are all the possible (due to the size limitation) candidates from digikey. You might be able to find other caps from other venders that might fit but in my oppinion the BC component is pretty good already, plus.... well, they are all super cheap anyway. One bonus when using the Panasonics ECWF though, is that they are the shortest in the group (the Epcos MKP is as short but obviously you wouldn't want to use it), and allows two 0.1uf/630v X2 series high voltage power cap to stay on top, as seen in the picture below. These three 0.1uf X2 caps in the picture will provide 0.3uf for high voltage power reserve, about enough if you are not a bass head. (bass heads should try to add more caps elsewhere and try to reach 0.5uf or a little higher, but there is no need to push above 1uf). 







 Boutique output caps and input BlackGates are still being burnt-in, result will come out in about a week.

 Stay tuned.


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## webbie64

Thanks for the update, audiocats.

 Definitely staying tuned - each episode keeps building up the excitement (anticipation)


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## krmathis

Thanks for the update!
 I am watching this thread closely. Cause if the result turn out to be a major improvement I might end up buying the SR-001MK2 again and get it modified.

 Keep us posted!


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## AudioCats

while the blackgates and Sonic caps are still being bombarded/tortured by friendly musical electrons, lets talk about power.... Obviously the best power source is large capacity pure DC ( ie battery banks), but AC adaptors are (or can be) still great for desktop use, since they just keep on going 24/7. The most commonly found/used AC adaptors are the Sony and Panasonic 4.5V discman wallwarts. Here is a review on the sonic difference between these wallwarts. We will also take a look at higher power options, ie. regulated power supply. 

 (Left to right: Sony 4.5V/500mA; Panasonic 4.5v/800mA; modified 5V/1A, originally for external zip drives)






 Test configurations: 
 Everything in the SRM-001 is done like what will be in a FatCat class mod, except the input electrolytics are still 22uf tantalum (since the blackgates NX's are still being burnt in). C17/18 are using 220uf/16v miniature aluminum electrolytics, C26/27 are 47uf BlackGates PK miniature (you can also use the same 220uf/16 as in C17/18 position, I installed PK because I am out of 220uf miniatures). The results below will be what happen with these power sources driving a FatCat SRM-001 (SRM-001-FC?). 

 Now the shoot-out:

 * Panasonic: 
 --in previous posts I have mentioned this wallwart gave a hum.... that was during minimun cap size testing, and with the AD825 installed. In the FatCat/SuperFatCat mod we use 220uf +/- caps and 8599, with this configuration there is basically no hum from any of the wallwarts. 
 --The sound: a little layback and distant; has a emphasis in mids therefore showes vocal charactoristic very well, especially if the voice is "raspy and gritty". Some minute details don't stand out very well, possibly due to the mids emphasis, this gives a false sense of "cleaner" sound when playing vocal tracks. Strong bass, good texture. The sound stage is the narrowest of the group.
 -- measures 4.61V under load.

 *Sony:
 -- the first thing you will notice is the sound is Soft. Showes details better than the Panasonic, larger sound stage. Bass is a little drier, and not showing bass texture very well. Kind of strange, all the details are there, but I sense a layer of haze.....
 -- measures 4.67V under load.

 *Modified 5v/1A regulated zip wallwart.
 -- the zip wallwart requires quite some modification, first of all you will have to change the plug to fit the SRM's jack. In my previous posts I have mentioned when the zip wallwart (before mod) was plugged in, the sound was good for the first 2 seconds then got very bad. I first thought the slightly higher voltage (5V vs. 4.6v) caused the SRM's inverter to act up, but latter thought it could be the inverter's pulse spikes going back into the wallwart and confused the regulator chip. Now it seems that the pulse spike is indeed the cause. After adding a CLC filtering circuit (regulator -> 2200uf cap -> small coil -> 4400uf cap ->output), the wallwart now works very well. The purpose of the filter stage is mainly to prevent the high frequency inverter pulse from reaching regulator. The 4400uf cap also acts as a power reservoir, it might not have to be that big, I put it in simply because I had one laying around and it would fit into the case. 
 -- The sound is analytical, well, kind of. Showes lots of details clearly, great bass thump(relatively speaking) and texture. It manage to show the sounds a lot better than the above two without letting you enjoy a lot more..... 
	

	
	
		
		

		
		
	


	




 Strangly wide sound stage, almost speaker like (again, relatively speaking), the sound field is diffused and doesn't allow easy instrument pin-pointing.
 -- voltage is 5.04V, regulated, same voltage loaded or not.

 * DC! Lithium batteries, 2000mAH capacity.
 -- I used two 14650 in parallel, they are older cell phone pack batteries so the capacity is only 2AH total. If you use the newest ultrafire 14500 (AA size, 900mAH each) you will get 1800mAH with two in parallel, the result should be the same as my test setup. 
 -- The batteries are about 3/4 full when tested, at 3.85V. 
 -- The cleanest sound so far, crispy and clear; intimate vocal, even better than the panasonic. It has the best bass thump, though the texture is slightly less "visible" than the modified zip wallwart. Sound stage wise is slightly larger than the Sony.

 It really surprised me that the power source actually made this much difference, I used to think since there is a step-up inverter inside the SRM-001 (all the actual amp power come from the inverter), the wallwarts should work the same as long as they provide enough current.... how wrong I was.
	

	
	
		
		

		
		
	


	



 Here is a summary of this power source comparison:
 (in the order of best -> not so great)
 *Bass thump: Lithium -> modified zip wallwart -> Panasonic -> Sony
 *Bass texture: Modified zip wallwart -> lithium -> Panasonic -> Sony
 *Vocal/mids: Lithium -> Panasonic -> Modified zip -> Sony
 *Details (high/mids fineness): Lithium & modified zip -> Sony -> Panasonic
 *Sound stage(wide -> narrow): Modified zip -> Lithium -> Sony -> Panasonic
 *sound locating: Lithium -> Panasonic -> Sony -> modified zip

 As we can see, the DC power is indeed the best overall, and the regulated high output power source doesn't necesary do that well. I have no idea why the Sony and Panasonic sound so different, they are just transformer/diodes/capacitor, unregulated output, both at 4.6V level...

 The conclusion:
 -- Pure DC is the best, get a bunch of 14500 lithium rechargable batteries and call it good 
	

	
	
		
		

		
		
	


	



 -- If you already have a wallwart of some kind and want to "upgrade" to a big-axx bench-top supply, well the expensive and super-stiff bench-tops might not give the best results with the SRM-001. Meanwhile, the smaller/lesser/more-cheaply-made regulated supplies might not work(or not as well as it could be) due to the inverter spike situation, some modification might be needed.... well, might as well inverst the benchtop PSU money for lithium rechargables and keep the wallwart for warm up purpose.
 -- or, if you have tax return $$ burning holes in your pocket/wallet/purse, get a bunch of different 4.5v-5v power supplies and do the experiment yourself, one will work best for a certain type of music while the other one best for another genre. Panasonic will be good for vocal (only), while a regulate supply, with that much details and good bass and super wide diffused sound stage will be the best for trence..... kind of like keeping different headphones you see 
	

	
	
		
		

		
		
	


	





 (I can't believe I put down this much BS just on power sources, it was supposed to be a short review.... 
	

	
	
		
		

		
		
	


	




)


----------



## HeadphoneAddict

Great, I have the Sony 4.5v on the left, and nothing to use it with. My SR-001 Mk2 will arrive Wednesday!

 I await your review of the differences. I also have a 5v wallwart that was for some Plantronics bluetooth earpiece for cell phones.

 Do we have to cut the cable and switch the tip to negative center, since my SRD-X 1/4" uses a 12v negative tip I thought maybe all STAX uses negative tip ?

 I also have a $90 regulated PS but it only does 12v-24v in 1v steps (4.5A), and doesn't go down to 4.5v. It does a great job with the SRD-X though.


----------



## AudioCats

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Do we have to cut the cable and switch the tip to negative center._

 

No! don't do it.....the SRM-001 power jack is the "normal" center + type, Panasonic and Sony 4.5v discman wallwarts will work as-is


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## HeadphoneAddict

I asked the question because "I never do before I do ask" as my grandaddy always said.

 Or, as Forest Gump would say, "Stupid is as Stupid does", and that wont describe me


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## pipoplus

Quote:


 * DC! Lithium batteries, 2000mAH capacity.
 -- If you use the newest ultrafire 14500 (AA size, 900mAH each) you will get 1800mAH with two in parallel, the result should be the same as my test setup.
 -- The batteries are about 3/4 full when tested, at 3.85V.
 -- The cleanest sound so far, crispy and clear; intimate vocal, even better than the panasonic. It has the best bass thump, though the texture is slightly less "visible" than the modified zip wallwart. Sound stage wise is slightly larger than the Sony. 
 

I also use 14500 Li-ion AA batteries in mine (only one at the time with a piece of copper as dummy, so you don't have to open the case ; Its a direct replacement)
 I gives me a few hours of runtime and I am very happy with the sound ;much better than normal batteries or the AC power sources I have tried.

 Audiocat: great topic you have here!


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## HeadphoneAddict

How many hours is "a few hours"?


----------



## sclee

Thank you for AudioCat tutorial,it a very useful.
 I just new entry to sr-001 for few week, the module still burning, as i like to listen the change of burning.

 Previously, i only want to use this on my travel on night at hotel, but after use i thing this can be compare as to or better to my using K701 system.

 The speed quick and not noticeable delay, when i come back to K701, the speed is so slow and sound push out some time. The bass is more better that entry level elec. phone such as 3030 and 2020

 I do not want to mod the unit so much, i study the amp, good design.
 I want to improve the speed and detail of sr-001.

 I like to change the 10uf 50v cap to Blackgate and paellel as a PP, i buy two 10uf 50v Blackgate N cap, but can not find good PP fitted on the room, because two BG is too big, so that i just use two BG and no PP.
 That mean the cap uf had been increase 10uf vs (10+0.15)/2 =5.075uf. Normal the speed become slow and bass increase

 But after i install and run few hour after, the speed is so great and faster that before about 50%. The bass is not much deep and open before, i know that should be burn at least 300 hr, as our K701 head amp BG output cap already run one year but also can listen the improve. 

 As i use a DC-AC selectable transformer with noise reduce function, i can not listen the noise even to the higher volume, i have 400ma and 800ma, a 800ma transformer have better bass detail and more deep.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *sclee* /img/forum/go_quote.gif 
_Thank you for AudioCat tutorial,it a very useful.
 I just new entry to sr-001 for few week, the module still burning, as i like to listen the change of burning.

 Previously, i only want to use this on my travel on night at hotel, but after use i thing this can be compare as to or better to my using K701 system.

 The speed quick and not noticeable delay, when i come back to K701, the speed is so slow and sound push out some time. The bass is more better that entry level elec. phone such as 3030 and 2020

 I do not want to mod the unit so much, i study the amp, good design.
 I want to improve the speed and detail of sr-001.

 I like to change the 10uf 50v cap to Blackgate and paellel as a PP, i buy two 10uf 50v Blackgate N cap, but can not find good PP fitted on the room, because two BG is too big, so that i just use two BG and no PP.
 That mean the cap uf had been increase 10uf vs (10+0.15)/2 =5.075uf. Normal the speed become slow and bass increase

 But after i install and run few hour after, the speed is so great and faster that before about 50%. The bass is not much deep and open before, i know that should be burn at least 300 hr, as our K701 head amp BG output cap already run one year but also can listen the improve. 

 As i use a DC-AC selectable transformer with noise reduce function, i can not listen the noise even to the higher volume, i have 400ma and 800ma, a 800ma transformer have better bass detail and more deep._

 

1st POST! Welcome to head-fi, and sorry about your wallet!


----------



## Faust2D

I used a Panasonic 4.5v/1500mA and it sounds much better than Sony discman wallwart.


----------



## HeadphoneAddict

I have two spare 4.5V wallwarts. The Sony, and a RadioShack 4.5v/6v switchable 550ma in the attached photo, which I have been happy with. The RadioShack has the same size tip as the sony, but can accept different sized tips which can flip for a polarity change.

 I also have a RadioShack 3v/4.5v/6v/9v/12v switchable with 1000ma that runs my SRD-X nicely. I suppose I can try all three.


----------



## AudioCats

Quote:


  Originally Posted by *sclee* /img/forum/go_quote.gif 
_Thank you for AudioCat tutorial,it a very useful.
 I just new entry to sr-001 for few week, the module still burning, as i like to listen the change of burning.

 Previously, i only want to use this on my travel on night at hotel, but after use i thing this can be compare as to or better to my using K701 system.

 The speed quick and not noticeable delay, when i come back to K701, the speed is so slow and sound push out some time. The bass is more better that entry level elec. phone such as 3030 and 2020

 I do not want to mod the unit so much, i study the amp, good design.
 I want to improve the speed and detail of sr-001.

 I like to change the 10uf 50v cap to Blackgate and paellel as a PP, i buy two 10uf 50v Blackgate N cap, but can not find good PP fitted on the room, because two BG is too big, so that i just use two BG and no PP.
 That mean the cap uf had been increase 10uf vs (10+0.15)/2 =5.075uf. Normal the speed become slow and bass increase

 But after i install and run few hour after, the speed is so great and faster that before about 50%. The bass is not much deep and open before, i know that should be burn at least 300 hr, as our K701 head amp BG output cap already run one year but also can listen the improve. 

 As i use a DC-AC selectable transformer with noise reduce function, i can not listen the noise even to the higher volume, i have 400ma and 800ma, a 800ma transformer have better bass detail and more deep._

 

The first thing you should change is the opamp. If you don't want to mess with the high voltage section too much, change the C6 to a 0.1uf/630v X2 series polyprop, that will increase your high voltage reserve 10X and fits directly onto the board. It will open up the highs and extend the bass quite a bit. 

 10uf/50V N is too big, but the DC component there (assuming you are talking about the input caps) is only about 1.5V, so the 22uf/6.3v NX will fit nicely onto the board. with that you can still add a 0.15uf polyprop as by-pass cap.
 If you are not a bass head, you really only need about 4-6uf as input caps. I have tested with a pair of FKP 6.8uf/150v polyprop (huge, about the size of battery compartment) and the sound was nice and smooth, good bass but not as much as I want though (after all, my first pair of good headphones are the 600 ohm version Beyer 990)

 I personally don't think the stock 001 is as fine as a 701/good amp combo. I can use a pair of silver/teflon recabled iGrado (driving by a PPA type amp) to compete with the stock SRS-001 (on two NiMH batteries), the stock 001 will win some area while the silver-iGrado/ppa will win the others, kind of breaking even. Upon direct comparison though, the dynamic phones always sound hazy, as if looking though a layer of thin fiber.... 

 I'd like to hear some comparison result of FC/SFC modded 001 vs. K701 driven by a $300 amp. Will be interesting.


----------



## sclee

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_The first thing you should change is the opamp. If you don't want to mess with the high voltage section too much, change the C6 to a 0.1uf/630v X2 series polyprop, that will increase your high voltage reserve 10X and fits directly onto the board. It will open up the highs and extend the bass quite a bit. 

 10uf/50V N is too big, but the DC component there (assuming you are talking about the input caps) is only about 1.5V, so the 22uf/6.3v NX will fit nicely onto the board. with that you can still add a 0.15uf polyprop as by-pass cap.
 If you are not a bass head, you really only need about 4-6uf as input caps. I have tested with a pair of FKP 6.8uf/150v polyprop (huge, about the size of battery compartment) and the sound was nice and smooth, good bass but not as much as I want though (after all, my first pair of good headphones are the 600 ohm version Beyer 990)

 I personally don't think the stock 001 is as fine as a 701/good amp combo. I can use a pair of silver/teflon recabled iGrado (driving by a PPA type amp) to compete with the stock SRS-001 (on two NiMH batteries), the stock 001 will win some area while the silver-iGrado/ppa will win the others, kind of breaking even. Upon direct comparison though, the dynamic phones always sound hazy, as if looking though a layer of thin fiber.... 

 I'd like to hear some comparison result of FC/SFC modded 001 vs. K701 driven by a $300 amp. Will be interesting._

 

How the affect for 0.15uf by-pass cap when i use higher or lower value PP cap ?

 I don't thing on two NiMH batteries SRS001 can be better that K701, at least use 4.5v power to SR001. K701 good on big and complex such as Symphony. But SR001 better on solo or Concerto, the brass,guitar, wind and volin. The detail of instrutment can be fully delivery as like real thing, the K701 more dynamic and deeper bass .

 The cable between sound source and amp will affect the sound so much on SR001, so that should be use good 3.5mm plug


----------



## pipoplus

Quote:


 How many hours is "a few hours"? 
 

two hours runtime on 1 Li-ion 14500


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## AudioCats

the reason for 0.12uf (sorry, I got it wrong, should be 0.12 instead of 0.15) is that will be the largest value polyprop that can fit onto the board as a direct replacement of the original 0.15uf poly(ester?). of course you can use smaller value, I have a habit of using as large and as nice a cap as possible, so the 0.12uf/63v was the default choice for me.

 On AC adaptor the stock 001 can beat the silver-iGrado/PPA, but I have no confidence with it competing with the 701 (on the other hand I have never compare the silver-iGrado with a 701 either).

 Yes the baby stax is unforgiving (a lot more so after the mods), you can hear all kinds of problems in your system, wrong cable, bad recording files, bad source...... sorry about your wallet



 only 2 hours on a 14500 in a stock 001? It only draw about 220mA, I though the 14500 should last at least three hours....


----------



## pipoplus

Quote:


 only 2 hours on a 14500 in a stock 001? It only draw about 220mA, I though the 14500 should last at least three hours. 
 

Can also be three hours (I hate looking at the clock when I am lying in bed listening to music 
	

	
	
		
		

		
		
	


	




) Also I try not to run them dry (I am using protected cells though)


----------



## sclee

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_the reason for 0.12uf (sorry, I got it wrong, should be 0.12 instead of 0.15) is that will be the largest value polyprop that can fit onto the board as a direct replacement of the original 0.15uf poly(ester?). of course you can use smaller value, I have a habit of using as large and as nice a cap as possible, so the 0.12uf/63v was the default choice for me.

 On AC adaptor the stock 001 can beat the silver-iGrado/PPA, but I have no confidence with it competing with the 701 (on the other hand I have never compare the silver-iGrado with a 701 either).

 Yes the baby stax is unforgiving (a lot more so after the mods), you can hear all kinds of problems in your system, wrong cable, bad recording files, bad source...... sorry about your wallet



 only 2 hours on a 14500 in a stock 001? It only draw about 220mA, I though the 14500 should last at least three hours....
	

	
	
		
		

		
		
	


	


_

 


 Finally I added the epcos 0.10uf 63v which can fitted to the 50v 10uf BG N Cap, i also change 5 0.01uf to WIMA RED MKP 0.01uf to improve the performance.

 I alsp want to change the 3.5mm phone jack to a better one, but now i am seeking and can not found high grade jack.


----------



## AudioCats

Finally the blackGates burn-in is completed. I connected them all in parallel and act as the output filter stage for a headphone jack, then I let them run for 24/7 for two weeks (more or less, I had to turn it down a bit when I go to sleep, and sometime I forgot to turn it on after CD change). Using the headphones I can hear how the burn-in changes the sound: at first it was muddy and bass heavy, after two days it started to clear up, then at around one week the sound became very sharp and metallic, then it slowly smooth out. Not sure if that was a 100% accurate impression since I was using two pairs of different headphones alternately…. But anyway, burn-in did change sound for the BlackGates. Picture below is the “board of blackGates” 
	

	
	
		
		

		
		
	


	









 Now the output caps burn-in: I connected the sonic I & II in parallel with the blackgates and run together, but apparently low voltage burn-in doesn’t work for high voltage caps, I could hear the sound change after installing them into the 001. Fortunately the sound settled down after about 3 hours. I am sure it will require more time to fully settle down but I think after 8 hours they are stable enough to get a impression, longer burn-in just improve what is already there. All three (Sonic I, II, and Auri) got 8-10 hours run time in the amp prior to the listening test.

 This will be a long report. I have fund the 001 is so sensitive to input cap / output cap / IC combinations, that comparing just individual components doesn’t give conclusive results. The same component can have totally different effect in different configurations. I will separate the contents into four posts instead of one super long report. The detailed list of parts-to-use-and-things-to-do in different class mods will follow shortly after.


----------



## AudioCats

Interconnects can cause major sonic difference here, it is more about using the “right” IC in the combination instead of using a “better” one, plugging in a more resolving/ more expensive IC doesn’t guarantee a better sound. So, check your IC inventory to see what you already have and what you plan to buy for your other audio gears, then pick a mod package. Using the wrong IC can cause unbearable sonic results, the baby stax will make sure you hear the mismatch …..The cost difference between different classes can be cheaper than the cost of another good cable. 

 The FatCat class uses non-boutique output caps with AD8599 as opamps. In general, this class prefers more bass-heavy IC’s, such as the tri-braid Teflon/silver and Esoteric Musica200 I used. (the M200 is a relatively inexpensive IC, $20-$40 price range). I have also tried quad-braid Teflon/silver, twisted pair Teflon/silver, quad-braid cotton/copper, Teflon/sivler in parallel PVC tubes, and the tri-braid turned out to be the “right one” (while in general the quad-braid Teflon/silver is considered as a better IC). This probably have something to do with the output cap selection, the winner is BC component MKP 0.011uf/630v, this cap is gives a lot of details but is a little overly bright (comparing to the boutique caps that it). By the way, this mod class prefers the tri-braid silver over quad-braid silver regardless of which non-boutique output cap was used (cap test results in post #20). 
 In lower price IC’s, my Musica200 sounds pretty good while the Monster Interlink250 sounds more detailed but is also too bright for long term listening, at least not for me. 

 The Super and Ultra class uses boutique output caps and you MUST use fast and cool/cold cables (I used twisted silver and quad silver). Install a tri-braid IC then the sound will get thick and chunky and chewy, all the tasty goodies are there but it won’t flow well, kind of like soup instead of wine (try to drink some chunky chicken noodle soup straight from the can then you will know what I mean). This is still true with AD825’s installed in the Ultra.
 IC selection for these two classes is at least a little easier than in the FatCat class, at least it looks like better cables give better sound. However, my cotton/copper quad-braid also works pretty well which really surprised me since it sounds like crap in my dynamic system (the problem was bland sound and dry bass, resolution was good)…..Also, the Monster Interlink sounds much better than M200, the 200 sounds veiled and layback and there is actually less bass 
	

	
	
		
		

		
		
	


	




……

 For those of you that don’t believe expensive cables make better sound but still want to get a 001 and mod it, stick with the FatCat mods, it is a little bit easier to find less expensive cable to match it.


----------



## AudioCats

Input caps (top left to right: BlackGate NX 22uf/6.3v, old tantalum 100uf/16v, old dip tantalum 22uf/10uf; bottom left to right: NX 47uf/6.3v, N 33uf/16v, NX 100uf/6.3v) 








 Output caps (left to right: Auri 0.01uf/600v, Sonic I 0.022uf/600v, Sonic II 0.0091uf/600v, the blue ones are BC MKP 0.011uf/630v.)








 Cap test rig (two input caps on top, four output caps into the lower sockets)


----------



## AudioCats

The cable used was tri-braid silver, power was lithium batteries with about ¾ charge. Signal source was modified Sony X555ES cdp (with 8599 opamp upgrade and two Auri 12uf inside. This CDP has pretty good resolution and speed – it uses not two, but six dual-opamps in the output stage ).

 The best output cap that I have tried in the FatCat class is BC component 0.011uf/630v MKP and that is what the 001 had during this test. A FatCat 001 with BC cap, in general, yield much stronger bass than the Super and Ultra 001’s, but with less details and more recognizable distortion. It is also sharper (what it shows really stands out) and more raw-sounding, not as smoothed-over like in the higher level mods. With the right input cap the bass texture really shows. It is great for listening to live performance, it just sounds, well, live! The sound fills up the space… It is more also impressive, if you want to get the “Ah” and “wow” from somebody, have him listen to a FatCat 001…. 

 All the caps below were connected in parallel with a pair of BC component 0.12uf/63v polyprop by-pass caps when tested.

 *47uf/6.3v NX BlackGate -- good everything, great bass impact, but not much texture showing.

 *100uf/16v tantalum – sharp/metallic sounding but shows less details than the BlackGates. Probably treble emphasized; less bass than 4.7uf NX, and not much texture.

 *22uf/10v dip tantalum – not as sharp as the 100uf tantalum. Great texture (really shows). The sound is more mid-range emphasized. Details wise, about the same as the 100uf tantalum. In general the BlackGates give better details than the non-boutique electrolytics.

 *22uf/6.3v NX – very spacious sounding, ok bass impact, not much texture; fast and bright.

 *33uf/16v N -- relatively mids emphasized, darker, and smoother than the ones above. Strong bass impact, but texture is not very good (somehow reminds me of bass from dynamic phones). 

 *100uf/6.3v NX -- very soft sounding, that is all I can say. 

 *the original 10uf/35v United-Chemicon (possibly a SME series) aluminum electrolytic –- very muddled sounding.
 * various other 47-220uf aluminum electrolytics I have in the parts box) –-not much better than the 10uf UnitedChemicon. In general the higher ripple/lower ESR ones, like Jamico WG series, sounds a little more clear, but still not there with the BlackGates and tantalums.

 The overall winner --- I know I am gonna get beat-up by the audiophiles for this --- is the 22uf/10v dip tantalum. Yes the tantalum isn’t very linear but relatively speaking, this one impressed me the most. I suppose if I listen to the 47uf NX more I could like it more but I am a kind of a bass head (still in the Nile) and the bass texture really impressed me. Don’t ask me what make/model/parts # those tantalums are, I truly don’t know, if I remembered right they were taken from an old computer power supply (therefore more burnt-in than any of the BlackGates). Maybe after more burn-in the 47uf NX will start to show good textures too, but not when I did this test. 

 Recommendations: buy some dip tantalums when you order the mod parts from digi-key and try them out and find the best one…. That way all mod parts will come from one source, you don’t have to place another order to partsconnexion or SoniCraft, this will save you like $10 on shipping alone…


----------



## AudioCats

Test conditions: 
 IC-- quad braid silver/Teflon; 
 power -- lithium rechargeable at full to ¾ full; 
 signal source – modded X555ES.

 Again, if you want to do this mod (or the Ultra), please make sure you have clear and fast cables. When I first started the boutique cap test I was using the tri-braid (which was the winner for the FatCat 001) and the sound was so thick and chunky, I was very disappointed and depressed—seriously—for a few hours. Until I figured “might as well try my other silvers”……. 

 In the SuperFatCat class the opamp’s are still the easy-to-install AD8599’s, but we can use as much boutique stuff as we want, as long as there is room for it…. 

 Boutique output caps: 
 Generally speaking, the Sonic I sounds thinner and lighter than the II and Auri. It puts a lot of details right in front of you, has a wide sound stage, the most “visible” bass texture in the three (but not necessary more visible than the FatCat class), and is faster than the Sonic II. The Auri, on the other hand, is creamier (like what others have told me before), has as much detail as the Sonic I, but the details don’t stand out as much. Sonic II has the thickest and smoothest sound (which is not necessary a great thing), it doesn’t show as much detail as the Sonic I and Auri (but still more than the FatCat class). it is best with sharp sounding cables (with this cap installed, my twisted pair silver sounds better than quad-braid). 
 Comparing the three, I’d like to say Sonic I sounds like water, Auri like wine, while the Sonic II like broth…..,(or we can say the Sonic I = gin, Auri = whisky, Sonic II = cognag for all your drinkers, I hope this is a good analogy because I don’t even drink 
	

	
	
		
		

		
		
	


	




 ). Overall, I like the Auri’s slightly more when using the AD825, but that will be the Ultra class mods. Auri is also difficult to squeeze into the case, per the spec it will barely fit but I didn’t realize the lead wires are so thick (adds to the over all length and requires more room), or I might not have order them.
 Between the easy-to-install Sonic I and II, I wouldn’t say the Sonic I is always superior than the II, it also depends on what IC you already have and what source you will be using. For a I-mod with a short three wire cable the II might be a better choice.

 Input cap results (all parallel with 0.12uf BC polyprops):

*Sonic-I as output cap*:
 * 22uf/6.3v BlackGate NX – lots of details, light and fast. Slightly bright and thin. Wide sound stage. Bass ok. 

 * 33uf/16v N – rich, meaty, layback and slightly sluggish. Sound stage is not as wide as the 22uf NX.

 * 100uf/6.3v NX – better bass than the two above. Not as fast as 22uf NX but faster than 33uf N. More up front sounding (more mids?). 

 * 47uf/6.3v NX – sharp, fast, spacious (wide sound stage), good bass, good texture.

 * 100uf tantalum (might as well try them, right? 
	

	
	
		
		

		
		
	


	




 ) – clean but more constricted; mids-emphasized, veiled and less details than any of the blackGates.

 * 22uf dip tantalum – again mids-emphasized. Clean sound but slower and not as detailed as the blackgates.

 --- The overall winner is 47uf NX, though the 100uf NX might work better for cold sounding sources.



*Sonic II as output cap*:

 * 22uf/6.3v NX – good clarity, strong bass, natural sound stage (neither wide nor constricted), smoother than the 47uf NX below.

 * 100uf/6.3v NX – bright, bass shy and drier 
	

	
	
		
		

		
		
	


	




 You will probably jump up and say “how the hell….” Well, that was what I said. Checked the connection, caps were plugged in all the way. I am only writing down what I heard, not why --- 1-27-08: I went back to this one again. It appeared that there is (or supposed to have) bass, I can hear the attemps, but somehow the bass doesn't come out right therefore not being recognized as bass..... kind of like swing drum sticks really hard but not really hitting the drum.

 * 33uf/16v N – bright and cold but not as bad as the 100uf NX. Ok bass.

 * 47uf/6.3v NX – similar to the 22uf NX but more spacious.

 * 22uf/10v dip tantalum – clean, not as much detail as the blackGates, but somehow is more “impressive sounding” than the blackGates.

 --- the overall winner is, again, the 47uf NX. If the source is a little “raw” "edgey", then the 22uf will smooth it out better. 

 Now some might ask what do I mean by “more impressive sound” like in the FatCat class… To me it means it grabs your attention right away and impress you right there, you don’t have to listen to it for a long time before realizing how good it actually is. How can this be? Well during the Seattle meet (last May), I was really more impressed by the AT AD2000 than the W5000, while the general consent is the W5000 is a “finer and better” phone. It is probably not just a personal taste thing, the finer stuff takes longer to enjoy, and you can enjoy it for longer period of time. I guess I can also say the “impressive” FatCat class is like hard liquor that gets you tipsy right away but you are always kind of standing (not fully convinced), while the SuperFatCat and the Ultra are like something smooth and by the time you realize it you are already on the floor, 100% taken over…. Again I hope this is a good analogy 
	

	
	
		
		

		
		
	


	




 Liquor experts please provide the proper name of the wine so I can refine my writing here


----------



## AudioCats

...... (deleted some unnecessary lines) 
 ....Also, I need to do some test without those 0.12uf BC polyprops and see how it sounds. The BlackGates are indeed so fast they might not need by-pass at all…..…..-- update 1-27-08: using the polyprop bypass caps is a *must*. It adds ambience, sparkle, and sharpness to the sound. The blackgates are fast sounding for being electrolytics, and that is about it. Without the polyprop bypass, the claps of hands can sound like slamming forarms together in some combinations, missing so much details that the sound was almost not recognizable. (I only knew they are claps because I am very familiar with that track 
	

	
	
		
		

		
		
	


	




 ) .

 1-27-08 Update:
 OK, enough rant, now the Ultra class results:
 --test conditions the same as above two classes. 

 --Notes on music used in these tests (all classes): the baby Stax excels at acustic music and vocal, so that is the kind of music I am tweaking it for. I use only three songs to evaluate each cap combination: _Cascade_ from Jesse Cook's _Montreal_ album ( acustic guitar, live performence to test ambience), _Pool of Dreams_ from Oracle's _Pool of Dreams_ album (bass presentation, details, and vocal naturalness), and _Call Off The Search _from a Katie Melua CD sampler disc ( intimacy of voice). I think these three tracks covered most of the test points pretty well.

 In the ultra class there is basically no limitatin on what to use as long as it can be put in the case. Opamps are AD825. All input caps are by-passed with 0.12uf BC polyprops. You might notice (yes you will) I also use 220uf/6.3v NX here, the reason why they were not listed in the above two classes was due to the size, they are simply too big for direct installation. But on the other hand the 220uf NX's don't sound good with AD8599 anyway (I actually did the tests, just didn't bother to include in the reports). 

*Auri as output:* 
 * 47uf NX -- too bright and thin.

 * 22uf NX -- all I can say is mediocre sounding.

 * 33uf/16v N -- good everything but not enough bass…..

 * 220uf NX – best ambience, best detail, good texture. I can listen to this one all day, and I have noticed I didn’t tend to turn the volume knob high in order to get into the sound. But the sound is not as sharp as I want. 
 Note: the 220uf NX’s weren’t burnt-in with the other blackGates. There was only about 4 hour of burn in done to them. I am sure the sharpness will improve after a full burn-in, lets hope the bass doesn’t get weak by then. 

 *100uf NX – thicker, darker sound and more layback, strong bass but not much texture.

 --- the overall winner here is the 220uf NX. I hope it will only get better with more run time. The second place is 33uf N (not everybody is a basshead after all).
 --- In general the Auri gives more/finer details than the Sonics (both I and II).


*Sonic generation I as output*:

 * 100uf NX – sharp and upfront, the bass didn’t impress me. Otherwise great.

 *47uf NX – more bass than the 100uf, good texture, but a bit too bright.

 *33uf/16v N – warm, the sound has a lot of weight. Lots of fine details, but not sharp/crispy enough. Not enough bass.

 *22uf NX – very sharp, treble/upper mids emphasized, gives a sense of great details. When listening to vocal I thought I heard the sticky lips closing/opening when the singer sings, and it shows the raspy-ness of voice very well, so well that I wonder if it is actually really like that…... Not enough bass.

 *220uf NX – the most impressive one of the group. Balanced, spacious, real, lots of weight, and good bass and texture.

 --- The 220uf NX is the winner, again. Some might also like the 22uf’s hyper details, again it is all system dependent.



*Sonic generation II as output:*

 *220uf NX --- good everything, nothing bad. Gives a slightly better feel than the Auri/220uf NX combo, but is not as detailed and not as much ambience.

 *47uf NX --- bright and cold.

 *33uf N – layback, distant, and very “fine” sounding. Doesn’t give me much enjoyment. Bass is good.

 *100uf NX – Sharper than the 220. not as much weight and ambience as the 220; more refined and polished sounding (not as "raw", probably due to missing minute details). Balanced and enjoyable. 

 --- yes you have guessed it, 220uf NX won again. The 100uf NX might work better for a more “raw” source though.



 Over all, I like the Auri/220uf NX combo the most. There is no absolute winner in the ultra class, at this level it is more about system matching and personal preference. 

 Now I think I understand why there aren’t too many people using electrostatics, it is so picky! “Better” components don’t necessary improve the final sound, everything is down to system matching once you have reached a certain height. Some of you might want to stick with dynamics where you can at least predict the results ….. (but you won’t get the crystal clear sound of the electrostatics 
	

	
	
		
		

		
		
	


	




 )


----------



## webbie64

Thanks for these updates, audiocats.

 You've been doing a LOT of work (and writing) and I just wanted to say it is genuinely appreciated out here.

 I look forward to the further details when those additional options are also done.

 Spare SRM-001 and soldering iron ready here...


----------



## d-cee

that's colossal

 good work and keep it up!

 we're all awaiting the results


----------



## AudioCats

Basically all straight forward direct parts replacements, expect the step where you add high voltage reservoir caps. This class requires the least skills.

 ----* Caution! Always make sure the batteries are out and AC is not plugged in whe you work on the PCB. You don't want to get zapped by the 550v charge from the little transformer on the board.
 ---- This to-do list is for info purpose only, you assume all risk associated with the modification. I can not be held accountable for anything happens to you (whether good or bad).

 A)Opamp upgrade –
 * Desolder the stock in-line-8 super slow opamps. If you don’t have a desolder station with air pump, the easiest way to do this is by bending the opamp back and forth until all the leads break off the chip, then desolder the leads off the board, one lead at a time. There is no need to save the stock opamps, you will never want to go back to it.
 * Clean up excessive solder around the holes, then solder the SOIC AD8599’s onto the existing pads on the board….
 * Parts Cost: about $15.

 B)+/- supply caps:
 -- replace C17 and C18. Absolute largest size you can use is 6.5mm (dia)x 13mm(high). My recommendation is United-Chemicon SMG 220uf/16v, (digi-key # 565-1038). The reason for using SMG is because it has the highest ripple rating in all the miniature 220uf/16v’s (rated at 260mA. The KMG is 180mA, Nichicon VR at 220mA). 
 Another viable option here is United-Chemicon NPCAP 100uf/16V, digi-key # 565-3053-ND, $0.75 each. Though the capacity is smaller than the SMG, it makes up in speed, the ripple current rating is 2820mA (not at the same frequency as the SMG rating, but I’d bet it is still much much faster than the SMG’s) . 
 * Parts cost: $1 to $1.5

 --Replace C27 and C28. The absolute largest size for these spots are 6.5mm (dia) x 8mm (h). The battery compartment reinforcement feature and contact wiring is in the way, so 8mm is about as high as you can go. Recommendation is Panasonic KA series 100uf/16v, (digi-key # P833-ND). 
 Parts cost: $0.30

 -- You can also add four more caps directly from the opamps’ VCC/Vdd pins to the ground. I will leave that to you, since it requires a bit of improvising. The caps to use will definitely be the United-Chemicon NPCAP 100uf/16v. As a matter of fact, if you decide to use the 100uf NPCAP in C17/18 location, you will really want to add these extra caps to make up the total capacitance. Adding a small film cap in parallel with the electrolytic for high frequency by-passing is also a good idea. 
 Parts cost: 0 to $5 depending on how many NPCAP you use.

 C) Short out R33/34/35. These were originally for forming a “pie” filter to clean up the +/- 12v supply, but the new opamps require a lot more current and these resistors create too much a voltage drop. Just add a piece of thin wire across the resistor ends and short them out.

 D) Replace the C3’s (two of them) with 1uf tantalum capacitor. First desolder the stock cap, then solder the surface mount tantalum chips onto the pad (on the under side). You can use low ESR tantalum chip like digi-key # 478-2412-1-ND, value is 1uf/35v. The reason for using SMD parts here is to clear up space so you have more possible space for more high voltage reservoir caps.
 -- parts cost: $2.5

 E) Desolder C1 and C2’s (four total); Install BC MKP 0.12uf/63v polyprop’s at C1 locations (digi-key # BC2056-ND, $0.68 each) and add two dip tantalums at C2 locations. I have no idea which tantalum dip will sound better, get a few different ones and try them out. The max size to use is 6mm(dia)x 13mm(h), here are two that might work: Panasonic 33uf/10v (PA2029-ND) and KMET 33uf/10v (399-3576-ND), both are less than $1.5 each. If you insist on not using tantalums as input but don’t have boutique caps to use either….. well, Digi-key does have Elna “audio capacitors” –-- “ ELNA developed new raw material for the separate paper which uses a silk fiber. Therefore, this series can give high grade sound for any audio design. This series can
 be used to relieve the music’s vibration energy, to decrease the peak feeling sound at high compass, rough quality sound at middle compass and to increase massive sound at low compass." (this is what it says on the digikey catalog). 
 Part # is 604-1051-ND, price is a whopping…. 15 cents each 
	

	
	
		
		

		
			




 -- parts cost: about $4.5, or less if you use Elna audio caps 
	

	
	
		
		

		
		
	


	




 F) Desolder C7 and C8’s (four total); Install BC MKP 0.011uf/630v caps (BC2240-ND). You can also use the larger values such as 0.016uf/630v, the physical size is the same as 0.011 caps, it probably won’t make any sonic difference when driving the SR-001. (But larger value will give better bass if you do end up using an adaptor cable to drive the small pro-bias phones like Gama Pro or SRX pro). 
 -- parts cost: about $3

 G) * Caution! Always make sure the batteries are out and AC is not plugged in whe you work on the PCB. Exercise extreme caution when wiring the high voltage caps since one mis-connection can fry the amp, the opamp stage will not survive a 550v hit.
 --Desolder C6; Add two pieces of wires to a 0.1uf/630v X2 cap’s leads (digikey # 496-1881-ND, $0.48 each) then solder the cap into the board. The purpose of the wires is for paralleling more 0.1uf/630v X2 caps to it. You might also want to order some 496-2319-ND, it is also 0.1uf/630v ($0.32 each) but is thinner and longer; having two different size caps will help you utilize whatever room is available inside the case. This requires you to improvise though. I will recommend ordering 3~5 of each part # just in case.
 You will want to pack in at least 0.3uf total (can easily be done), but there is no need to go higher than 0.8uf. Fix down the extra reservoir caps with hot glue (the good thing about hot glue is it hardens right a way, won’t smear, and if necessary, easier to get rid of later)
 -- parts cost: anywhere from $3 to $5. 

 H) Add a good electrolytic cap between ground and DC input + (after the switch). There are no existing holes/spots for you to do this, so I will leave this up to you. A good cap aross the DC power input can make quite some improvements in bass texture presentation. Or you can build an external power conditioning box (actually a cap box), but that will be before the switch and will not be as effective. More on the cap box later. 

 By doing these mods you will increased the opamp’s speed by 50 time, high voltage reserve by 30 to 50 times, and +/- reserve by 10 to 30 times (which is required by the faster opamp, so you don’t really have a choice here 
	

	
	
		
		

		
		
	


	




 ). All parts can be ordered from digi-key, total parts cost will be less than $40. Shipping/tax will likely be around $10, so < $50 all together. 

 -- Skill level required: if it wasn't for the Stax high temp (silver?) solder, I'd say it is a bit easier than building even the simplyest perf board Cmoy. At here you don't do wiring (except the paralleling more caps to X2 high voltage power reserve part), just replacing parts. 

 -- Total time to complete the FatCat class mods: anywhere from 45 minutes to 4 hours (from opening the case to closing the case), depending on your equipment and skill level. I can finish one within 45 minutes since I have access to an air pump desolder station, though I don’t see everybody using a station like that (the PACE 250 is more or less a $1200 machine). The mod is fully doable with just a pair of diagonal cutters, a pencil soldering iron, and a hot glue gun, less tool requirement than making a Altoids Cmoy. 
 If in doubt, go slow….. will be a fun little Sunday afternoon project.


----------



## AudioCats

Still mostly direct parts replacement, same skill level as the FatCat mods. 
 --Parts sources: SonicCraft BlackGates, SonicCaps; Partsconnexion film caps, BlackGates 

 ----* Caution! Always make sure the batteries are out and AC is not plugged in whe you work on the PCB. You don't want to get zapped by the 550v charge from the little transformer on the board.
 ---- This to-do list is for info purpose only, you assume all risk associated with the modification. I can not be held accountable for anything happens to you (whether good or bad).


 A)Opamp upgrade –
 * Desolder the stock in-line-8 super slow opamps. If you don’t have a desolder station with air pump, the easiest way to do this is by bending the opamp back and forth until all the leads break off the chip, then desolder the leads off the board, one lead at a time. There is no need to save the stock opamps, you will never want to go back to it.
 * Clean up excessive solder around the holes, then solder the SOIC AD8599’s onto the existing pads on the board….
 * Parts Cost: about $15.

 B)+/- supply caps:
 -- replace C17 and C18. Absolute largest size you can use is 6.5mm (dia)x 13mm(high). My recommendation is United-Chemicon SMG 220uf/16v, (digi-key # 565-1038). The reason for using SMG is because it has the highest ripple rating in all the miniature 220uf/16v’s (rated at 260mA. The KMG is 180mA, Nichicon VR at 220mA). 
 Another viable option here is United-Chemicon NPCAP 100uf/16V, digi-key # 565-3053-ND. Though the capacity smaller than the SMG, it makes up in speed, the ripple current rating is 2820mA (not at the same frequency as the SMG rating, but I’d bet it is still much much faster than the SMG’s) . 
 * Parts cost: $1 to $1.5

 --Replace C27 and C28. The absolute largest size for these spots are 6.5mm (dia) x 8mm (h). The battery compartment reinforcement feature and contact wiring is in the way, so 8mm is about as high as you can go. Recommendation is BlackGates PK series 47uf/16v. 
 All boutique caps can be ordered from SonicCraft (in Arkansas) or Partsconnecxion (in Canada). These two venders have basically the same price.
 Parts cost: $2

 -- add four fast electrolytics directly from the opamps’ VCC/Vdd pins to the ground. The caps to use will definitely be the United-Chemicon NPCAP 100uf/16v. Adding a small film cap in parallel with the electrolytic for high frequency by-passing is also a good idea. 
 Parts cost: 0 to $5 depending on how many NPCAP you use.

 C) Short out R33/34/35. These were originally for forming a “pie” filter to clean up the +/- 12v supply, but the new opamps require a lot more current and these resistors create too much a voltage drop. Just add a piece of thin wire across the resistor ends and short them out.

 D) Replace the C3’s (two of them) with BlackGates signal capacitors. Either the 1uf/50v N ($2.65 each) or 1uf/50v C ($1.45 each) will work, but the N is apparently a safer choice.
 -- parts cost: $3~ $5.3

 E) Desolder C1 and C2’s (four total); Install BC MKP 0.12uf/63v polyprop’s at C1 locations (digi-key # BC2056-ND, $0.68 each) and install two BlackGates signal caps to C2 locations. See the above cap test results for selection recommendations. If in doubt, use 47uf/6.3v NX, it might not be the best for your system but it is guaranteed to be at least good.
 -- parts cost: about $6.5 ~ $15 depending on the BlackGates.

 F) Desolder C7 and C8’s (four total); Install boutique output caps. Again see the cap test result above for some ideas on parts selection. If in doubt, use Sonic generatin I, you can choose from 0.01uf to 0.022uf, they will all fit on to the board. Again it might not be the best for your system but by picking this one you won’t mess up too badly.
 If you use Partsconnexion as your source ( they don’t carry Sonicaps), the Multicap PPMFX 0.01uf~0.047uf/600v will be the only options due to the size limitation. You might want to pick a larger value just in case you might drive other pro headphones in the future). The price range is basically the same as the Sonics, I have no idea how they sound and what input cap to match them with though. 
 -- parts cost: about $18

 G)** Caution! Always make sure the batteries are out and AC is not plugged in when you work on the PCB. Exercise extreme caution when wiring the high voltage caps since one mis-connection can fry the amp, the opamp stage will not survive a 550v hit.
 -- Desolder C6; Add two pieces of wires to a 0.1uf/630v X2 cap’s leads (digikey # 496-1881-ND, $0.48 each) then solder the cap into the board. The purpose of the wires is for paralleling more 0.1uf/630v X2 caps to it. You might also want to order some 496-2319-ND, it is also 0.1uf/630v ($0.32 each) but is thinner and longer; having two different size caps will help you utilize whatever room is available inside the case. This requires you to improvise though. I will recommend ordering 3~5 of each part # just in case.
 You will want to pack in at least 0.3uf total (can easily be done), but there is no need to go higher than 0.8uf. Fix down the extra reservoir caps with hot glue (the good thing about hot glue is it hardens right a way, won’t smear, and if necessary, easier to get rid of later)
 -- parts cost: anywhere from $3 to $5. 

 H) Add a good electrolytic cap between ground and DC input + (after the switch). There are no existing holes/spots for you to do this, so I will leave this up to you. A good cap across the DC power input can make quite some improvements in bass texture presentation. Or you can build an external power conditioning box (actually a cap box), but that will be before the switch and will not be as effective. More on the cap box later. 


 ----parts cost is less than $65, but you will have to get them from two different sources so there will be an extra $20 for shipping. $85 total.
 ---- You will want to use insulation sleeves on the output capacitor leads so there is no way they can zap the other parts by any kind of accident (plus it make them look "safer").



 FatCatUltra mods
 -- basically the same things to do as in the SuperFatCat mods, expect you will be trying to squeeze the Auri caps into meagerly available space in the 001 case, and you will have to make a quad SOIC --> SIP adaptor board so the 825’s can be used. You can see what I did in the opamp comparison post, I believe the pictures there showed enough info.
 -- The best input electrolytic cap to use with the AD825 is most likely the BlackGates 220uf/6.3v NX.
 -- the Ultra level is very depending on personal skill level and preference. If you find something works particularly well, please tell us 
	

	
	
		
		

		
		
	


	



 -- Parts cost will be about $30 more than than the Super (if you use Auri and 825's).


----------



## AudioCats

This one deserves a separate post. Important. 

 After the mods, the opamp stage will be drawing alot more power, the total current draw of the amp will be more than doubled (stock amp draws 220mA, while the FatCat and Super draws about 450, the Ultra draws 500mA). All these current goes into the step up inverter circuit on the PCB. The inverter is now working twice as hard, the Q15 (I suppose that is the swithing transistor --- update: not a switcher, but a linear voltage regulator) can get pretty hot, I will guesstimate the surface temperature reaching 80 degree C. And that is in the open air, it will only get hotter in the plastic case where air flow is restricted. Therefore, it will be a good idea to have a heatsink of some kind on Q15. I use a rubberized silicon thermo pad (patch)between the Q15 and the case wall so the heat will transfer to the case (using the plastic case as a heat sink). Will the Q15 get cooked if there is no thermo pad? probably not, just I don't want to take any chance.

 I don't know who sells just the thermo pads, mine were from surplus/left over heat sinks. Here is a heatsink that comes with thermo patch. It is quite a bit larger (so better) than the little pad I am using.







 I believe this will be all the info I have on the 001 mods. There might be a little update on the power conditioning cap box and the power source improvement later, but it might not be needed. After all, the battery DC is already proven to be the best there is……

 Better find your soldering irons guys 


 Have fun


 ---- 2-8-08: for more about the Q15 heat issue, see the updated post #57 in the next page.


----------



## AudioCats

caps on the way, lets hope the cap box can make the adaptors sound more like batteries......


----------



## HeadphoneAddict

With a stock SR-001 I tested battery life. At about 3 hours 15 minutes with a pair of NiMH 2000Mah AA batteries, I started to hear a drop in sound quality.

 I will keep listening till it becomes unbearable, but does this sound right?

 Am I correct that the parallel battery mod will get the same battery life from a pair of 900Mah 3.7v lithium batteries after the SuperFatCat, which means over twice as much power drain and still a solid 3 hours, right?


----------



## HeadphoneAddict

Still running at 4 hours, without further degradation in sound since 3:15


----------



## HeadphoneAddict

5 hours and still running with no further sound degradation since 3h:15m when it had a slight but noticeable drop.


----------



## AudioCats

the stock 001 drains about 220mA, so a set of 2000mAH batteries (series), in theory, should last 8 hours or so. Now that is if you run the batteries all the way down which is actually impossible since the sound will get worse once the voltage get below 2.5v (fully charged is about 2.7V, and supposedly fully drained being 2.4v).
 Also, since those are 2000mAH NiMH, I supposed they are at least three years old, the newer ones are already at 2600mAH. All common rechargable batteries have a service life of 3 years or less (even if you don't use them much, they will still age to death), it is possible the "used to be" 2000mAH capacity is now a lot less.

 Two 900mAH 14500 Ultra fire in parallel should give at least 3 hours of good sound, in a SFC'ed 001. One good thing about lithiums is even when they get really close to depletion, the voltage is still high enough (at least 2.5v) to provide acceptable performence. Once the voltage gets below 2.4v the protection circuit will cut off the current so you don't have to worry about it


----------



## HeadphoneAddict

It went 6 hours 5 minutes before dying, and the green light switched to red about 45 minutes before it died. It sounded decent until it died quickly over a short period of time and faded out as the NiMH batteries died.

 How long past the 3 hours will the parallel lithium batteries run before the superfatcat shuts off?


----------



## sclee

Is anyone use 4xNiMH battery box to SRM001 (4.8-5.6V ), will this damage for the amp.


----------



## AudioCats

4x will be too high, 2x too low, 3x NiMH should work great....

 -- Update on Q15 (the one that requires heatsink): I partially traced power supply circuit tonight, and it turned out the Q15 is not a switching transistor at all, it is part of a linear voltage regulation circuit to make sure the switching transistor will see about 2.6-2.7v. That is why it gets really hot if 5v is plugged in -- there will be a 2.3v voltage across Q15, with a estimated 400~450mA current it will have to dissipate about 1W !! 
 Since the transformer will only see 2.7v the most, there is really no need to use DC input higher than 3v, to be safe lets say 4v should be more than adaquate..... After all, the whole amp was designed around a pair of AA. I think all the 4.5v transformers perform better than a pair of NiMH AA's because the adaptor voltage is higher than 2.7v while the 2x NiMH is usually less. Once the voltage is above a certain level then only the current capability counts. That kind of explains why the Sony 4.5v/500mA sounds so different from the Panasonic 4.5v/800mA.... 

 So, to make sure Q15 doesn't over heat, it will be a good idea to keep the DC input between 3.5v~4v (the same voltage range as the lithium rechargables). That can be done by simply adding an extra diode in your 4.5v wallwart (not at the input jack, you don't want to lower the battery supply voltage) and use the 0.6v forward voltage drop to lower the Q15 voltage. That way the diode will get warm while the Q15 doesn't get too hot. 

 Have fun


----------



## AudioCats

Cap box "power conditioner", with 5 Panasonic FM 5600uf/10v caps (28,000uf total; using 10v caps because some 4.5v transformers' unloaded voltage can reach as high as 7v). There is a diode for polarity protection and provide a little forward voltage drop. I used a large power input jack because that is the only type left in my parts box 
	

	
	
		
		

		
		
	


	




 Does it work? yes and no. It does make the AC adaptors sound better, but I can still hear the wallwards "sound characteristics". With the cap box installed, the zip 5v still sound slightly hyper while the panasonic 4.5v/800mA still have a mid-range emphasis. (only able to compare these two since the power input jack doesn't allow the Sony to plug in. I have two Panasonic and two zip wallwarts so I converted one each to large plugs for testing).
 I was kind of hoping the large capacity cap bank can erase AC adaptor's "personality" and make them all sound like the battery, apparently it didn't work out that way. On the other hand, it is still quite nice to have something that can run 24/7 and sound this good. The 5v zip + capbox combo, though still a little "hyper", provides the best overall sound in all my wallwards. (The lithium rechargables, in comparason, is calmmer and has slightly more weight to it.)







 by the way, with the diode lowering the voltage down (3.8v output with Panasonic plugged in and 4.2v with Zip), the Q15 only gets slightly warm, no need to add the heatsink pad.

 Larry, I have received the parts from digikey, you can send your 001 over whenever you are ready 
	

	
	
		
		

		
		
	


	




 Have fun


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## HeadphoneAddict

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_4x will be too high, 2x too low, 3x NiMH should work great....

 -- Update on Q15 (the one that requires heatsink): I partially traced power supply circuit tonight, and it turned out the Q15 is not a switching transistor at all, it is part of a linear voltage regulation circuit to make sure the switching transistor will see about 2.6-2.7v. That is why it gets really hot if 5v is plugged in -- there will be a 2.3v voltage across Q15, with a estimated 400~450mA current it will have to dissipate about 1W !! 
 Since the transformer will only see 2.7v the most, there is really no need to use DC input higher than 3v, to be safe lets say 4v should be more than adaquate..... After all, the whole amp was designed around a pair of 1.5v AA (instead of the 1.2v NiMH), so all these make sense. I think all the 4.5v transformers perform better simply because of the higher current capability. That kind of explains why the Sony 4.5v/500mA sounds so different from the Panasonic 4.5v/800mA.... the voltage doesn't mean much, the current reserve does. 

 So, to make sure Q15 doesn't over heat, it will be a good idea to keep the DC input between 3.5v~4v (the same voltage range as the lithium rechargables). That can be done by simply adding a extra diode in your 4.5v wallwart (not at the input jack, you don't want to lower the battery supply voltage) and use the 0.6v forward voltage drop to lower the Q15 voltage. That way the diode will get warm while the Q15 doesn't get too hot. If the DC input is at 4v then the Q15 will only have to dissipate 0.5w, that wouldn't be a problem even without the help of a heatsink pad. 

 Have fun_

 

So, if the RadioShack wall wart I am using now gives me a choice of 3v or 4.5v and has a 1000MA rating, can I just use the 3v setting? If the transformer isn't seeing any more than 2.7v, then 3v should be enough if it can supply up to 1000ma, right?

 Right now at 4.5v the stock SR-001 does NOT get hot at all. I guess that at 220ma for a stock SR-001 that is why it isn't hot while I am using 4.5v, because the current draw is half that of the SuperFatCat, correct?


----------



## HeadphoneAddict

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_
 Larry, I have received the parts from digikey, you can send your 001 over whenever you are ready 
	

	
	
		
		

		
		
	


	




 Have fun_

 

I will be doing my stock SR-001 comparisons over the next day or two, and have 468 hours on the SR-001 already and it sounds nice. I have about 36 hours on the SR-003 that I am comparing to, but the SRM-1 Mk2 Pro is well burned in (thousands of hours I am guessing) and it sounds a little better already (even with less hours on the SR-003).

 I am also comparing to Denon C700 and Livewires customs, with RSA Predator amp and Meier Headsix amp. All of these are well burned in (Predator has 905 hours, Headsix has about 400 hours, Denon about 600 hours as do the Livewires). I just need to get notes written about what I hear with everything, and will try to ship Tuesday or Wednesday if I am not ready to get it out Monday.

 During that time I will keep burning-in the SR-003, until I am sure it is done changing.


----------



## AudioCats

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_So, if the RadioShack wall wart I am using now gives me a choice of 3v or 4.5v and has a 1000MA rating, can I just use the 3v setting? If the transformer isn't seeing any more than 2.7v, then 3v should be enough if it can supply up to 1000ma, right?
_

 

In theory the 3v should be good enough, though I would guess 3.5~3.7 being safer.... 

 by the way, is that a regulated supply?


----------



## AudioCats

You can get isolation and better bass by putting on a nice pair of close phones (like the Beyer 770, not plugged in of course), when listening to the baby stax.
 The closed housing provides the isolation, while the well designed Beyer driver diaphragm and rear chamber form a resonace chamber giving you strong clean bass..... kind of like marrying the Beyer and Stax together. And, since the Beyers will prevent the Baby stax from falling out, the 001/003 don't have to be pushed in as hard, there will be a lot less fatigue on the ear canals. Try it and you will like it 
 The best part: it won't degrade sound any more than using the stax head band.....


----------



## AudioCats

Just found out that not all SRM-001's are made the same. Mine came with NJM062L, and the one Larry just sent me has the Toshiba made 062, which sounds quite a bit better than the NJM, almost as good as a TL082 upgrade. 
 If you have Toshiba chips in your 001, you might not want to change the opamp, just upgrading the input/output caps should give satisfactory performence, and you still have the same battery life as the stock amp.


----------



## Faust2D

That's interesting. What is the serial number on the one with old Toshiba chips and what is the number on the one with NJM062L. I would bet it has to do with how old the unit is. They have been making them for a long time now.I was surprised that you SR-001 improved so much, since the one I have sounds great out of the box.


----------



## AudioCats

Mine (NJM chip) is 179x, the one larry has (Toshiba) is 18xx, the serial # isn't that far apart.

 All you have to do is open your little amp and take a look ....


----------



## ak40ozKevin

Mine is 21xx and I just bought it in November of '07. I checked the chip and it's the NJM model :'(

 I might consider upgrading since the amp circuit board looks simple enough. Right now I find the effects of EQ sufficient enough to shape the sound into what I want but my curiosity is growing.


----------



## Faust2D

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_Mine (NJM chip) is 179x, the one larry has (Toshiba) is 18xx, the serial # isn't that far apart.

 All you have to do is open your little amp and take a look .... 
	

	
	
		
		

		
		
	


	


_

 

Yeah, I will when I have time 
	

	
	
		
		

		
		
	


	




 I just want to find a pattern to this.


----------



## HeadphoneAddict

I can't find an S/N on the Mk1, either externally or in the battery compartment - do I have to crack it open to find out? There is a number on the box that looks like it would be a serial number 00159, but it doesn't say serial number or anything next to it. Anyway, I am doing a comparison of Mk1 to Mk2 before I send Mk1 out for the mods on Monday. 

 According to AudioCats, his SFC with AD8599 still sounds better than my Mk2, by about 50%, while his SFC was 100% better than his stock Mk2. We'll see.


----------



## HeadphoneAddict

Well,

 The Mk2 I have looks like serial number SA1-1538 (not 18xx), while the Mk1 doesn't have a SN sticker on it, but the original box has a number 00157 on it.

 I opened the Mk1 and the main board is labeled PB-101 (while the Mk2 is labeled PB-102).

 The opamp is still a TA75062S like the Mk2, BUT the chip in the Mk2 says "Toshiba Japan" and the Mk1 just has a "big letter T on the chip, followed by the same TA75062S and then a smaller 5H at the end".

 Nevertheless, the Mk1 doesn't sound as open and transparent to me as the Mk2. So, I plan to ship out the Mk1 Monday to AudioCats for the SFC with AD8599 and parallel battery mod, and I will include the 4 Lithium batteries and charger. Plus If I have time to get some bigger tips then I'll send the radio shack wall wart from the first time, with a bigger tip for his cap box. 

 When he is done with the mods he will ship it to another Head-Fier to compare to SR-003/SRM-313. Then I will get it back to compare to stock SR-001 Mk2 and SR-003/SRM-1 Mk2 Pro.


----------



## AudioCats

woops, I guessed the serial # wrong 
	

	
	
		
		

		
		
	


	




 (I was looking at the picture I took and there was a glare on the silver serial # lable, I thought it must be a "8", now it turns out to be a "5"..... 
	

	
	
		
		

		
		
	


	




)


----------



## AudioCats

Just realized Ultrafire protected 14500 is not truly AA size, the protection board extended the length about 2mm, too long to go into the battery bay. If you are going the lithium 14500 route, the un-protected cells can still be use, just make sure you always use the dedicated lithium charger and turn off the amp when the sound gets bad.....
 left to right: AA alkaline, AA NimH rechargable, and the Ultrafire protected cell


----------



## pipoplus

Quote:


 Just realized Ultrafire protected 14500 is not truly AA size, the protection board extended the length about 2mm, too long to go into the battery bay. 
 

I have the same protected Ultrafires. It is tight (with the spring flat) but they will fit.


----------



## AudioCats

really? the one I have here (from Larry) will not, the battery itself is longer than the bay -- the bay opening is 51mm, the battery is about 52mm.... can you post a picture of your ultrafire standing next to a AA alkaline? I wonder if they do design changes all the time.


----------



## AudioCats

SFC mod officially finished (for HeadphoneAddict). And mostly likely it will be the last SFC I will ever do.... it requires way too much little tweaks to fit everything into the case. If the battery bay space is available it will be a lot easier.
 Total mod time is a lot longer than I expected, I thought 90 minutes ought to be enough, it turned out to be about 4 hours. And that is not counting dealing with the Ultrafire issue (that part is done today).

 A: after desoldering everything, and scrapped off the solder mask off the SOIC pads, added solder. This one is a MK1 board, if you are doing MK2 there is no need to worry about the solder mask.
 Time for desoldering: 15 minutes.
 Time for dealing with the soldering mask: 15 minutes.






 B: After installing the 8599's and the Sonic Caps. you can still see the liquid flux on the board, it was latter washed off in hot water.







 C: All parts installed. The whole case is filled to the brim now. I really wanted to have 0.5uf high voltage reserve, but the space only allowed 0.4uf, absolutly no way to add another cap. so bass might suffer a little. 






 D: battery bay conversion







 E: All cased up, ready to go back to Larry.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_really? the one I have here (from Larry) will not, the battery itself is longer than the bay -- the bay opening is 51mm, the battery is about 52mm.... can you post a picture of your ultrafire standing next to a AA alkaline? I wonder if they do design changes all the time._

 

Well, look at it this way, you squeezed the battery's protection circuit into the SRM-001 unit, so I can use normal 14500 now anyways. That's a good thing.


----------



## pipoplus

Quote:


 really? the one I have here (from Larry) will not, the battery itself is longer than the bay -- the bay opening is 51mm, the battery is about 52mm.... can you post a picture of your ultrafire standing next to a AA alkaline? I wonder if they do design changes all the time.
 __________________ 
 

I measured the battery 51,8mm long (it is a trustfire I use not an ultrafire but just as long) . I have got a MK1 version of the SRM-001 so maybe that is why
 I will take a picture later.


----------



## HeadphoneAddict

The one just modded is a Mk1 too.


----------



## AudioCats

Both the MK1 and MK2 has the same battery bay openning length, both 51mm.

 I opened the protected cells and took out the circuit boards, then hard wired one board inside the 001 amp. here are some observations:
 1) the ultrafire board cuts off at 3v, instead of the more common 2.5v. So you should always have good sound as long as the amp runs, until the amp turns itself off (then you get no sound at all 
	

	
	
		
		

		
			





). Not sure how much battery life reduction this will cause, since the power is cut-off before the battery is fully depleted.

 2) the protection board was designed to be hard wired onto the battery, it is designed to freak out when seeing 0 volt which means the battery is permernently dead. But in this case the circuit is installed in the amp (the load), the 0 volt situation happens when you take the batteries out of the battery bay during a battery change. Therefore, when changing batteries, you will have to leave the battery bay empty for a few minutes so the protection board can reset itself, before installing the fresh battery.


----------



## HeadphoneAddict

With Parallel Battery mod, can't you just swap one of the partially discharged batteries with a full one, then swap the other, so the protection board still sees 3V but just half the amperage for that 2-3 seconds?

 Also, if I get horrible battery life, unprotected cells can be bought with more Mah than protected, right?

 Lastly, peeps here should know that there was not enough room for a normal size protection board, so this was the only option to protect the cells. Otherwise, forgetting to shut it off when the batteries run low, like falling asleep while listening could harm the cells. AND, now the cells are not protected from overcharging unless you have a special Lithium battery charger (like mine).


----------



## AudioCats

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_With Parallel Battery mod, can't you just swap one of the partially discharged batteries with a full one, then swap the other, so the protection board still sees 3V but just half the amperage for that 2-3 seconds?_

 

NO NO NO!
	

	
	
		
		

		
		
	


	




 the two batteries recepticles are connected in paralle, if you take just one empty battery out and install a full one, the full one will have much higher voltage than the other empty one (still in the battery bay), so the full one will try very very hard to charge the empty one by sending tons of current, it is almost like a short, this will harm both batteries....now you know why I heatshrinked them two in red two in blue, so you won't mix the empty with the full by mistake. 

  Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_ Also, if I get horrible battery life, unprotected cells can be bought with more Mah than protected, right?_

 

I think they are the same.... unless you can find the Sony 1100mAH info-lithiums for a good price (and I don't remember the model # for the sony).


----------



## pipoplus

Great modding job Audiocats!

 Here is the promised photo with the longer (51,3-51,8 mm) protected 14500 Li-ion battery
 The tip of the battery is just small enough to squeeze in between. You have to roll the battery out so using more than one (only if you did the parallel batteries mod!) it is harder to get them out. 
 I still think you better use protected Li-ions; they shut down when they are getting low and you don't want to charge depleted Li-ions. Building a protection circuit inside is to much trouble for most.
 These trustfires are also cheap ($6 shipped) 






 Although it is a MK1 set; My SRM-001 got a (*T* TA75062S .6G) in it and the mainboard is a PB-102 with the number 08444-00134 on it an with 03185 on the serial label. It seems like this is yet another variation.


----------



## AudioCats

Quote:


  Originally Posted by *pipoplus* /img/forum/go_quote.gif 
_I still think you better use protected Li-ions; they shut down when they are getting low and you don't want to charge depleted Li-ions. Building a protection circuit inside is to much trouble for most.
 These trustfires are also cheap ($6 shipped) 
_

 

Thanks for the photo 
	

	
	
		
		

		
		
	


	



 agree, it is always better to have a protection board. That is why I squezzed in the ultrafire's protection board into the amp itself, so whatever is in the battery bay will be protected 
	

	
	
		
		

		
		
	


	




 by the way, if you like how your MK1 sounds, try some MK2 phones when you have a chance, you will be amazed


----------



## HeadphoneAddict

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_NO NO NO!
	

	
	
		
		

		
		
	


	




 the two batteries recepticles are connected in paralle, if you take just one empty battery out and install a full one, the full one will have much higher voltage than the other empty one (still in the battery bay), so the full one will try very very hard to charge the empty one by sending tons of current, it is almost like a short, this will harm both batteries....now you know why I heatshrinked them two in red two in blue, so you won't mix the empty with the full by mistake. 


 I think they are the same.... unless you can find the Sony 1100mAH info-lithiums for a good price (and I don't remember the model # for the sony)._

 

So, if you pull one discharged battery out you have to pull out the other, because if one unprotected-drained battery is still installed then it could be harmed if the full one is inserted first, even if the drained battery is removed within "a couple of seconds" of inserting the full one. Wow. That's crazy.

 Anyway pipoplus, my SR-001 now has the protection circuit built-in, so the pair of batteries cannot be over-discharged below 3.0v, so I can use unprotected cells if I want to. I just have to be careful charging those cells in a proper charger, since they CAN be overcharged without the protection circuit that was pulled out of all of them (so they would fit). 

 The Ultrafire lithium battery charger that I have will not overcharge unprotected Lithium 14500 batteries. So, we should be good on that end too. My Ultrafire can even charge them in the car with the optional cable I have for it.


----------



## AudioCats

Update: battery life issue
 just did the battery life test, the amp turns off at about 3 hours on a pair of freshly charged batteries. Current draw is about 480mA which is about the same as my modded MK2 board with 8599 installed. In theory a pair of 900mAH should last a little longer, like 3.5hr or so. Two factors can cause the shorter battery time:
 1) the higher cut off voltage of ultrafire protection board. The power is cut off a little too early, before the battery is really depleted. Not much I can do about that, since the ultrafire board is the only one that can fit in (and even with that, I still had to fight to squeeze it in).

 2)the rapid charger might not be fully charging the batteries. I have read the rapid chargers only do the stage-1 charging that is why it is so "rapid", and stage-1 only fill to about 70%. I am charging one pair of ultrafire in my "non-rapid" charger, will do the bettery life test on that pair tomorrow night and see if there is any difference....


----------



## HeadphoneAddict

One thing I can consider is that if the issue is the rapid charger, then I'll just buy a better charger that does a "more complete" job.

 Likewise, if you guys can find protected cells that do fit two at a time, and they last longer than 3 hours in your units, then I could remove the protection board from the SR-001 Mk1 and buy those same protected batteries.

 Or, I'll either search for lithium batteries with more than 900mah, or just live with 6 hours from 4 cells.


----------



## pipoplus

here you can find high grade Li-ion batteries. I also believe they sell protected 14500 in normal AA size and "real" 750mAh.
 Having fitting 14500's is also a big issue in flashlight country


----------



## HeadphoneAddict

BatteryJunction.com has them in 900mah protected (52mm too long) but also 900mah unprotected (50mm which fit)


----------



## AudioCats

SFC update:
 * the rapid charger is probably not the main problem on battery life issue. It took my slow charger over 10 hours to charge a pair of ultrafire, and the run time is 2 hour 50minutes, about the same as the rapid chargers. 
 Since you can use the unprotected cells in the battery bay, it is probably cheaper to just get one more pair of batteries. 

 * The amp is now pretty stable. It was quite warm for the first two days, I could feel it on both top and underside of the plastic case, which made me kind of worried because the +/- supply caps are right above the opamps and I think most of the heat came from teh opamp. High temperature is never a good thing for electrolytics. (though the UnitedChemicon PS caps are rated for 105C operation, so really there is no need to worry.) Now the case is only slightly warm, I think the burn-in of the opamp is nearly completed.

 larry, the package will be sent back tomorrow afternoon. After receiving it, you probably still want to do two more days of burn in. It has about 60 hours on it right now, and according the AnalogDevice, BJT opamps need 70-100 hours to fully stablize. (I think the 8599's are BJT input, since the input impedance is quite low -- comparing to the FET input opamps it is).-- update: ok the 8599 is not BJT, it is still FET input, I got it mixed up with the 797 
	

	
	
		
		

		
		
	


	




... anyway, more burn-in won't hurt 
	

	
	
		
		

		
		
	


	




 by the way, I have put the original parts (taken off the MKI board) in the package too, and two of the ultrafire protection boards, just in case you might need them for whatever reason. I am keeping one ultrafire pretectin board, I will see if I can come up with a protection/dummy cell so you can use the lithiums in your stock MKII.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_SFC update:
 * the rapid charger is probably not the main problem on battery life issue. It took my slow charger over 10 hours to charge a pair of ultrafire, and the run time is 2 hour 50minutes, about the same as the rapid chargers. 
 Since you can use the unprotected cells in the battery bay, it is probably cheaper to just get one more pair of batteries. 

 * The amp have become pretty stable. It was quite warm for the first two days, I could feel it on both top and the underside of the plastic case, which made me kind of worried since the +/- supply caps are right above the opamps and I am pretty sure most of the heat came from teh opamp, high temperature is never a good thing for electrolytics. (though the UnitedChemicon PS caps are rated for 105C operation, so really there is no need to worry.) Now the case is only getting slightly warm, I think the burn-in of the opamp is nearly completed.

 larry, the package will be sent back tomorrow afternoon. After receiving it, you probably still want to do two more days of burn in. It has about 60 hours on it right now, and according the AnalogDevice, BJT opamps need 70-100 hours to fully stablize. (I think the 8599's are BJT input, since the input impedance is quite low -- comparing to the FET input opamps it is). So two more days should do it.

 by the way, I have put the original parts (taken off the MKI board) in the package too, and two of the ultrafire protection boards, just in case you might need them for whatever reason. I am keeping one ultrafire pretectin board, I will see if I can come up with a protection/dummy cell so you can use the lithiums in your stock MKII._

 

Sounds like a plan. I would love a dummy protection cell for my stock Mk2!


----------



## borisov57

Great work AudioCats.

 I replaced input electrolytics with 47u/6.3 NX today. Difference is big. There is less distortion and details are coming in from darker background. I am awaiting AD8599s, some X2s and MKPs. 

 Have a nice day


----------



## AudioCats

Thanks borisov57, please keep us updated.

 Protecting the 001 cables:
 There has been at least two reports on 001 cables failing within one year, and in both case the problem area was where the ribbon meets the plug, which makes me suspect repeated bending in small radius is the problem. So I did a little experiment to see how sharp the cables can be bent, and I didn't like what I saw.... In my case the plug end is not too serious a problem, what really scared me was where the cable going into the phones, the bending is just too sharp, looked like it was gonna fail right there 
	

	
	
		
		

		
			










 To ameliorate the situation, I think some gentle reinforcement at the plug/cable stress spots will help. I cleaned the cable/plug surface with alcohol (to get rid of oil/grease), and stick on small stripps of self-adhesive velour felt tape. It appears to work pretty well, even with extreme bending, the radius of the bend is still _relativly_ large, the cable curves gradually.... Lets hope the velour will stick on there for a long time.






 And the best part is, this protection costs almost nothing 
	

	
	
		
		

		
		
	


	







 Have fun


----------



## pipoplus

good tip!
 I such situations i use heatshrink for "a wider curve"


----------



## HeadphoneAddict

I am working on my review of the SFC vs Stock, just an FYI, and will post as a new thread when I am done, and will put a link to it here.


----------



## borisov57

Hello,

 Here is picture of changed input and output caps. Input is BG 47u/6V3 NX and output caps are Wima polypropylen 47n/630V. Power supply cap is Epcos X2 100n. 
 After this photo was taken, I changed four power supply caps (10u/25V) with 100u/25V Rubycon ZLG and bypassed BGs with 68p silver mica.

 Best regards


----------



## HeadphoneAddict

*PART ONE - Super Fat Cat SR-001 Mk1 vs Stock SR-001 Mk2*

 I have been listening to the SFC a bit, and it was running 24 hr a day since I got it back, until I put 300 more hours on it. When the SR-001 Mk1 was stock, I did not like the sound. It was as bad or worse than the stock Mk2 before the Mk2 was burned-in, yet had hundreds of hours on it. The mids were peaked so the FM transistor radio sound that Audiocats once mentioned in the past was there. In contrast, my stock Mk2 after 350-400 hours was very listenable, but not as transparent as my Denon C700 or Livewires with portable amp. Dynamics were good, and bass was good if using the headband, but it still was possible to hear "the sound of the Mk2", and not the sound of the actual recording. 

 Once the SFC was done and came back, the differences were subtle (in that the sound signature was similar) but noticeable. If I just look at the two different amps (SFC Mk1 and stock Mk2) with the same earpieces - *the modded SFC Mk1 with the good sounding earpieces clearly sounds better than it did stock.* With the same earpieces in my ear, and swapping the amps, I can hear some subtle differences with the stock Mk2 amp and the SFC amp. Not as big as expected, but the Mk2 already sounds pretty good after 500 hours. *The SFC treble has a little more shimmer than the stock Mk2, and the bass is a little more powerful than the stock Mk2. The SFC also has a little more air and depth. I find that the SFC sounds very much like the SR-003 on the desktop amp (SRM-1 Mk2 Pro), which is better than the stock SR-001 Mk2.*

*By using one earset, and switching only the two amps, the I can pick out the SFC SFC every time.*

 Addendum: One of my problems is that I was 99.9% sure I didn't mix up the Mk1 and Mk2 ear-pieces, but the ones that I thought were the used Mk1 earpieces sounded a little better in the SFC, while the newer looking ones might have a slight peak or coloration, maybe in the 4Khz - 8Khz region. While the ones I thought were the Mk1 earpieces don't have this peak, and they might have more bass with the SFC. I say "might" to both of those issues because I can't quantify those differences, it was just something vague in the back of my mind. However, those same older looking earpieces sound worse with the stock Mk2 than the newer looking earpieces.

 So, what I am hearing is that BOTH sets of earpieces (Mk1 & Mk2) sound good with the SFC, but with the stock Mk2 the newer/unscratched ones sound better than the older looking ones. I think the SFC has the ability to drive the Mk1 earpieces better than a stock Mk1 or stock Mk2 amp.

*PART 2 (COMING SOON) - Comparing the SFC and Stock SR-001 to Dynamic Portable setup using Denon AH-C700 and Livewires Customs with RSA Predator. (I will probably post a new new thread at that time, but I am not done yet)*


----------



## HeadphoneAddict

Sorry this is taking so long. I got tied up with my mini-review of USB DAC Amps, and then my TTVJ Portable Millet Hybrid review.


----------



## AudioCats

Thanks for the impressions Larry.

 Strangely, what I remembered was (when both driven by the SFC) the MK2 phones (mine, probably have a few hundred hours more than your MK2) have more details and extend further on both top and bottom end than the MK1 phones, and I clearly prefered them over the MK1 phones, especially with Jazz tracks. 

 I agree that there is a peak somewhere, it is more obvious when using the SFC (8599 + Sonic1 output). The AD825+Auri combo has less such problem, though still there. But..... the 8599/Sonic1 gives the best "feel" when listening to jazz, I simply don't get the feel when using the 825/Auri combo, despite 825/Auri being a little more detailed, a little faster, and has less of that "coloration". 

 by the way, will you still send the SFC to Catscratch for the 001/SFC vs. 003/SRM313 comparison? 

 Have fun


----------



## AudioCats

Quote:


  Originally Posted by *borisov57* /img/forum/go_quote.gif 
_After this photo was taken, I changed four power supply caps (10u/25V) with 100u/25V Rubycon ZLG and bypassed BGs with 68p silver mica.




_

 

looking good, I have never used the ZLG before though. since you are still using the stock 062 opamps, which has a current draw 1/30 of the AD8599's, there is really no need to use caps larger than 22uf at those locations. If you ever think the sound might be boomy, installing 22uf~47uf fast caps such as BG std, PK and tantalum might give good results (the C26/27 locations are especialy sensitive to cap's speed).... Just a thought.

 Have fun


----------



## HeadphoneAddict

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_
 Thanks for the impressions Larry.

 ...by the way, will you still send the SFC to Catscratch for the 001/SFC vs. 003/SRM313 comparison? 
_

 

Yes, once I finish the second part of the review - portable stat vs portable dynamic. If you can forward me the name, address, email and phone for where to send it that would help.

 Larry


----------



## borisov57

I am listening right now to vinyl to hdcd transfer of Beatles Hard Day's Night. Oh boy, it sounds great.
 Thanks for tips AudioCats. If I would have BG at hand, it would be in. And one day it will be.

 Have a nice day


----------



## AudioCats

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Yes, once I finish the second part of the review - portable stat vs portable dynamic. If you can forward me the name, address, email and phone for where to send it that would help.

 Larry_

 

I will ask him for the contact info after you finished your review. By the way, I still haven't finish the protection/dummy cell for using li-ion in the stock amp yet, but I got a new idea on doing that, will let you know how it goes in a couple of weeks.


----------



## AudioCats

some ideas on how to do SFC++ (better performence, but have to use an external power pack).

 Variation-1 (this particular one will likely go to Morphsci):
 This variation is mainly for desktop use, but still fully portable, battery life is intended to be 15 hours (3x 2600mAH lithium cells). 
 Desktop mode
 -- the RCA cables plugs into the rear of power pack and came out as mini pigtail that plugs into the 001. This is serving as a RCA/mini adaptor. 
 --Charger plugs in from the side (not enough estate in the back end to add the charger jack). 
 --battery pack pigtail will come up between the two RCA jacks and plugs into the 001's power jack (just imaging the black wire is the power pigtail 
	

	
	
		
		

		
		
	


	




).
 --The mini jack on the side of the battery box is for "parking" the mini pigtail when in portable mode.
 -- 3 position locking switch on the front, positions will be "B" (battery run), "C/A" (slow charge while running on AC for warm-up), and "CH" (amp off, charge only. This will charge the batteries faster). Still have to figure out the circuit layout though. Will probably add a few indicator LED's as well. 






 Portable mode:
 -- mini pigtail (of the RCA/mini adaptor) parks in the "designated parking spot", nothing will be tangling.
 -- you will be using a mini-mini interconnect to deliver signal directly to the amp.







 RCA jacks are Vampire CM1F. I had a hard time getting cable-end RCA jacks, so I broke down and got chassis jacks and mount them to the box. Not too expensive, looks better too.
 -- You can see the little hole between the RCA jacks, that is where the power pigtail cable will come out. 






 in this variation, the on-off can be controlled by either the 3-position switch in the battery box or the 001 amp's volume knob.


----------



## AudioCats

Variation-2, portable with battery box and loose rechargable NimH batteries.
 -- this one shows a Sony box, which holds four C cells. One cell will be replaced by a dummy cell, so the total voltage will be 4v fully charged. Batteries will be charged outside. 
 -- the battery box is thicker than the Stax amp, but if you add your MP3 player on top the the amp (self-adhesive velcro?), then they will be about the same.








 Variation-3, portable with lithium rechargable packs.
 -- on the left shows a 5-cell pack, you can use 5x 18500 cells (7000mAh=1400mAH x5=7000mAh, roughly 13-14 hours per pack). Make two battery packs so you can have one plugged in the charger while the other one is in use. battery packs will fit into some sort of cell phone carry pouch.
 -- the one on the right is two 18650 cells in the carry pouch, if using 2600mAh cells you will have 5200mAH capacity, probably last 10 hours. A smaller pouch can be used.


----------



## borisov57

Hello,

 I just added two 14500 Li-ion batteries. Sounds much better than NiMh, and also better than 4.5 V supply, that I used. Li-ion sounds cleaner across whole spectrum and has more treble energy.
 I am using un-protected batteries. What could get wrong, if I discharge them to much?

 Have a nice day


----------



## AudioCats

Over discharge could cause some kind of internal damage to the battery, so when they are charged again, metal lithium might form and eventually short out the plates internally, then all the energy stored in the battery at that time would be released in a hurry and cause some sort of cook-off.....
 At least in theory that can happen. 

 By the way, how did you get the case to close with c26/C27 being that tall?


----------



## ericj

Exploding lithium batteries are a reality - usually in the form of defective laptop and cell phone packs though. Which are in theory protected packs.


----------



## AudioCats

I think the main problem is the heat generated from other circuitry. Probably not directly the lithium battery's fault.


----------



## borisov57

Thanks guys for info about lithium batteries. I will get protected ones and I hope they will fit in. So far, I get a lot of playing time, before voltage drops to 3V, because i have original Toshiba opamp in ( maybe 6 to 8 hours).

 Audiocats:
 Is is not hight of cap, that is problematic in C26 and C27 position but battery connection. I have C26 and C27 angled in direction of input caps, as can be seen in picture.


 P.S.

 I have measured high voltage with Ni-MH and external 4.5 V supply and it was cca. 420 vs. cca. 600V.


----------



## AudioCats

A different tip option: 






 This tip (softies?) came with my 2nd SRS-001 set from Canada. I supposed it is some kind of IEM silicon sleeve, quite comfortable. Being a non-IEM person I have no idea what exactly it is, you will have to ask dunk7 for that. The only problem is this sleeve make the driver a little further (by about 1mm) away from the ear openning, so there is a slight "hollowness". 
 But the benefit far outweight that little problem: with this sleeve, a good seal is basically guarranteed, no need to do "baby stax face" at all. Bass is improved in a major way. The over all effect is kind of like how the Lambda react with the yellow foam removed-- big bass, slight hollowness.
 To my ears, the recently finished SFC001++RVC with this sleeve is as good as (or slightly more enjoyable than) my SR-Lambda/SRM-1 combo.


----------



## webbie64

Looks to me like the tips I use with my Sony Noise Cancelling Ear Buds.






  Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_A different tip option: 





 This tip (softies?) came with my 2nd SRS-001 set from Canada. I supposed it is some kind of IEM silicon sleeve, quite comfortable. Being a non-IEM person I have no idea what exactly it is, you will have to ask dunk7 for that. The only problem is this sleeve make the driver a little further (by about 1mm) away from the ear openning, so there is a slight "hollowness". 
 But the benefit far outweight that little problem: with this sleeve, a good seal is basically guarranteed, no need to do "baby stax face" at all. Bass is improved in a major way. The over all effect is kind of like how the Lambda react with the yellow foam removed-- big bass, slight hollowness.
 To my ears, the recently finished SFC001++RVC with this sleeve is as good as (or slightly more enjoyable than) my SR-Lambda/SRM-1 combo._


----------



## Faust2D

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_A different tip option: 





 This tip (softies?) came with my 2nd SRS-001 set from Canada. I supposed it is some kind of IEM silicon sleeve, quite comfortable. Being a non-IEM person I have no idea what exactly it is, you will have to ask dunk7 for that. The only problem is this sleeve make the driver a little further (by about 1mm) away from the ear openning, so there is a slight "hollowness". 
 But the benefit far outweight that little problem: with this sleeve, a good seal is basically guarranteed, no need to do "baby stax face" at all. Bass is improved in a major way. The over all effect is kind of like how the Lambda react with the yellow foam removed-- big bass, slight hollowness.
 To my ears, the recently finished SFC001++RVC with this sleeve is as good as (or slightly more enjoyable than) my SR-Lambda/SRM-1 combo._

 

I tried Sony tips with my sr-001, looked very similar to these. Unfortunately I did not like the sound with them at all. Bass became to muddy and overpowered and a strange reverberation coloration was introduced. A tried another type of the foam tip but it was also bad, so far I like small original tips the best.


----------



## AudioCats

yes the sound with the sleeve is a little boomy and echoy, but for a bass-head like me... big bass, me like 
	

	
	
		
		

		
		
	


	



 The original tips usually give a "drier" sound, they perform the best when the ear is very moist like right after a hot shower.


----------



## Faust2D

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_yes the sound with the sleeve is a little boomy and echoy, but for a bass-head like me... big bass, me like 
	

	
	
		
		

		
		
	


	



 The original tips usually give a "drier" sound, they perform the best when the ear is very moist like right after a hot shower._

 

If you like a lot of bass, I guess this mod will be a good thing 
	

	
	
		
		

		
		
	


	




 I just hate any kind of boomy reverberation added to my music.


----------



## AudioCats

ok, turned out the olive tip thingey is not as good as I thought. After a few days of listening, the boomyness finally got to me and I put back the original stax tips. The same on my Lambda's, I re-installed the original yellow dampening material. 

 And I finally broke down and did a quick comparision between the SFC++ and my second 001 (which has serial of 16xx and has Toshiba chips inside). The Toshiba chip stock 001 is pretty good, it sounds a bit warmer, moddier, softer, more layback, and quite a bit darker when comparing to the modded amp.


----------



## borisov57

Yesterday, I forgot to turn off srm-001, powered by unprotected Li-Ion. Red lite went on, batteries were at 2.5V. Than I took them out, and there voltage climbed to 3V. I carefully recharged them and everything seems fine. Anyway, protected cells are on there way, and I hope, they will fit in.

 Boy, those baby staxes sound so good, I can't stop listening to them. I am going full size stax soon, but I am very limited by budget.


----------



## AudioCats

Here is the link to Catscratch's review on the SFC++ 001 (this amp went to Morphsci). 
 The mod in the review is a SFC++RC (intended mostly for rock/classical, but Catscratch liked it more for electronics), using 0.22uf Auri by-passing 47uf BlackGate NX as input. +/- power has 660uf per side, and high voltage reservoir is 0.6uf. Opamps are the standard 8599 (therefor still a SFC mod). 
 The input Auri caps and +/- supply caps are stored in the battery compartment, so the amp requires external power to run. The power base/box contains 3x 2600mAH Samsang li-on cells, provids about 15hr of run time with a full charge.


----------



## AudioCats

Quote:


  Originally Posted by *borisov57* /img/forum/go_quote.gif 
_Yesterday, I forgot to turn off srm-001, powered by unprotected Li-Ion. Red lite went on, batteries were at 2.5V._

 

2.5v is safe. The potential problem is if the amp is still left running after the red light turns on, and it will run until the voltage drops down to about 1.7v before turning itself off.....1.7v is a bit too low per the safety spec.


----------



## borisov57

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_2.5v is safe. The potential problem is if the amp is still left running after the red light turns on, and it will run until the voltage drops down to about 1.7v before turning itself off.....1.7v is a bit too low per the safety spec._

 

Thanks audiocats. I have bought protected ultrafire cells and I am using them now.
 I am still impressed every time that I listen to this system. Full size Staxes will be my next step.

 Have a nice day


----------



## AudioCats

here is an idea for all you brave souls in eastern Europe, where surplus teflon caps are abundant....






 I finally received some Soviet 0.22uf/600v FT3 teflon caps this afternoon. Couldn't help it, I just had to soldered on some long leads and connected them into my 001 test setup 
	

	
	
		
		

		
		
	


	




 they are brand new and need burn-in, so I guess I might as well use the 001's output stage for that task 
	

	
	
		
		

		
		
	


	




 These caps are so huge, you almost don't see the little amp board behind them. But the sound is great, I will put it this way, it is well worth the trouble to add a big "output cap box" underneith the little amp (like of like the battery base in the SFC++ setup), and turn it into a semi-desktup setup. 
 Makes me wonder how much better it can get once these teflons are fully burnt-in. At this point (2 hours) it is still a little too smooth though.


----------



## webbie64

So what do you call this one, Audiocats? The Super Fantastico Fat Cat??


----------



## HeadphoneAddict

Super Fat Cat SE

 (for Special Edition or Supremo Extreme)


----------



## webbie64

Can't wait to see it cased 
	

	
	
		
		

		
			





 And then I guess the only thing left will be how to incorporate tubes and work the words 'portable' 'blue' and 'hawaii' into a name...


----------



## AudioCats

I doubt it will be necessary to use tubes...

 Anyway, since over sized caps will be in a additional enclusure attached to the amp, much like a booster rocket attached to a main engine to boost the power, I'd like to name the new mod after historical aero space carriers.... and these teflon are from former Soviet, so, this one will be the *Proton* mod 
	

	
	
		
		

		
		
	


	




 (sorry, have been watching too much Discovery channel lately)

 Now, if that isn't crazy enough, how about a *Saturn-V* mod? With a 15hr power pack (maybe we can call it the _fuel module_), and a cap pack (with V-caps and Mundorf silve/Gold, called the _booster module_, to boost SQ that is).
	

	
	
		
		

		
		
	


	






 teflon SQ update: 24hours into burn-in. So far the only difference I can tell (comparing to the 2hr sound), is the bass texture, it got a little more visible. I will draw the conclusion when it hits the 150hr mark.


----------



## AudioCats

some thoughts for all you 001 fanatics:

 I can pretty much predict the extreme mods now, it will use 4x opa627, and run on tri-voltage battery pack (+15v, -15v, and +4v). I/O caps can be V-cap OIMP as input and V-cap teflon as output. This will pretty much be the absolute extreme for the SRM-001 mods, the _*Saturn-V*_. (meanwhile the *Delta-IV *will use the AD825 with Auri/V-cap teflon I/O, and *Proton-K* will be AD825 with Auri/FT-3 teflon I/O. Yes, I like to create mod names 
	

	
	
		
		

		
		
	


	




).

 The possible price for this kind of mods (including a power pack), if somebody want to do it without losing money (say, @$20/hr, which is actually impossible to run a real bussiness on), the _Proton-k_ have to go $450, the _Delta-IV _$600, and the _Saturn-V_ probably $1000 (with a build-in Vcap ipod LOD though) Nuts an't it, with the mod price of a _Saturn-V_ you can just go out and get a pair of 003 and a used T-1 amp, though they wouldn't run in a business brief case 

 I only plan to try out the opa627/tri-power and test it with _Proton_ I/O's, since I already have most of the parts. The _Delta_ or _Saturn_ parts will be way too expensive for me. But I can see some crazy head-fi'er CEO's might be desperately needing the _Saturn-V_ system when on a business trip.... 
	

	
	
		
		

		
		
	


	




 Have fun


----------



## borisov57

Hi AudioCats,

 Maybe you could use OPA637, which is faster and is stable at gain of 5.

 Have a nice day


----------



## AudioCats

hehe, I already have some SOIC 627's so that is what I will use. My 637's are in dip packaging, a bit too big to fit in


----------



## borisov57

Hello,

 If size any money is no problem, I would try Russian NOS silvered mica caps for output caps. 

 Best regards from Slovenia


----------



## AudioCats

Borisov, did you mean that you _will _try out the silver/mica for us? 
	

	
	
		
		

		
		
	


	




 I assume you can get them easier locally, no?

 I have checked out the silver/mica auctions on ebay, it seem like they are mostly 350/500v parts, I would have to get two of larger value and wire them in series...the size of 8 silver/mica will be pretty huge, approaching the size of four 0.1uf FT-3 teflon.
 I _might_ try some 1000v PIO K40Y instead, they are a bit smaller. The question is, is there really a need to do all these testing? I am pretty sure the expensive caps, such as silver/oil and V-cap teflon will outperform any cheaper caps. Since the 001's output stage is the actual bottle-neck in the system and I don't know what mod I can do to it (any suggestions without a complete rebuild?), I will need all the capacitor help available. So I will probably end up trying silver-oil or V-cap, pretty soon.
 I couldn't make up my mind, so I bought some lottory tickets today. If I win more than $50 I will try silver/oil, if more than $100 I will go for the V-caps. 
 Otherwise...... the old plan, FT-3 teflons that I already have 
	

	
	
		
		

		
		
	


	




 pray for my lottory win guys, if you want to 
	

	
	
		
		

		
		
	


	




 ---- one week later.... hey, you guys didn't pray hard enough or not the right way or somebody prayed backwards. whichever way, I didn't win anything, as usual 
	

	
	
		
		

		
		
	


	




 so I take it as a sign: no extra fancy caps mods from now on.


----------



## AudioCats

teflon burn-in, 120 hours: the sound turned very raw. I can hear more, but that includes more problems, some probably due to recording, some due to the other area of my system. No longer overly smooth, instead not smooth enough. 

 90% of my CD's are now unlistenable. The rest 10% sound so very good but most of my favorits are not among them.
 Maybe the extra transparency is exactly what the 001 _doesn't_ need. 

 If the sound keeps going this direction, I can see the idea of ultra high-end output caps gets ditched very quickly 
	

	
	
		
		

		
		
	


	




 lets see if it gets any better in the next 150 hrs.


----------



## oicdn

SWEET. Battery life doesn't bother me much (granted I don't get it until tomorrow), but can these mods be performed WITHOUT having to use an external battery pack? Atleast, something very similar?


----------



## slwiser

Make sure you get a sony ac adapter that feeds it 4.5 volts like I have.


----------



## oicdn

^ How many mA will my wallwart need to be? I think I have a couple laying around that are 4.5v...


----------



## slwiser

Quote:


  Originally Posted by *oicdn* /img/forum/go_quote.gif 
_^ How many mA will my wallwart need to be? I think I have a couple laying around that are 4.5v..._

 

If no one else responds I will have to check out mine at work tomorrow and get back with you. I really enjoy this setup at work. It is open enough and closed enough and very good sound. I also use the Sanyo batteries that are low discharge when on battery power.


----------



## AudioCats

you will need at least 500mA of current, voltage can be between 3V and 5V. It wouldn't be a good idea to go over 5v since there will be quite some voltage drop on Q15 and it will get hot.

 Of course, the more current reserve the better, but it is hard to find a low voltage power supply with higher than 1A output. I personally prefer the un-regulated power supply, somehow the regulated PSU make the sound a little "hyper" (possibly due to over compensating for the step-up power system in the amp).


----------



## sclee

I come back and use the sr001 for more that 4mouths, and didn't work on any mod, for almost 5mouth run time, the blackgate and sr001 burn in (Acturally use 200hr
	

	
	
		
		

		
		
	


	




)

 I want work on improvement because i see here so many update, and thing that the system can be improve, i real don't like the radio transparent sound but real like that musical and warm sound esp vocal, as i use belden sliver coat 3.5mm connect line as little become cold. 

 After study catscratch and here i just thing that:
 The opamp affect the sound of sr001 as like opamp affect on normal headamp
 Prevent sr001 sound and reduce radio transparent.

 All AD opamp have problem is high precision but not musical, i don't like use AD on headamp but i like it DAC.

 So that i plan use the NE5532 which Audiocats proved it can use on sr001 and only consume 400ma. I will use philips NE5532 ceramic which 
 provide warm but clear and good speed sound that normal NE5532.

 I will working on change the opamp on weekend.
	

	
	
		
		

		
		
	


	




 I also want to use the OPA2134, i thing OPA627 and OPA637 more speed - but for listening, a OPA2134 metal case will be better, but i don't know need of current for OPA2134, so that i will set the NE5532 first and test one channel OPA2134 (I only have one OPA2134) to see is it can work.


----------



## borisov57

Maybe someone has sr-001 headphone connector pinout?


----------



## sclee

We changed the opamp of the sr-001 amp to NE5532FE Philips ceramic, i thing i can direct solder a DIP8 on the PCB surface but it don't have enough room for do that, so that i solder the NE5532 and connect the other four pin by wire.

 I changed the four power supply 10uf cap to 100uf Nichicon HD cap and shorted R33,R34,R35 i change the 1uf 50v C3 cap to BG PK.

 When i first operated, i can not see any red or green LED light up, only listen the startup transformer sound.

 I check all of the circuit and don't found any problem 
	

	
	
		
		

		
			





 i disassemble of R33 R34 R35, the green light up. We short those again and i work. 
	

	
	
		
		

		
		
	


	




 I also make a super cap box with 1 diode reduce the 4.5v power supply to 3.8v, 2x 10000uf Rubycon 16v and 1x ELNA AUDIO 3300uf 42v to provide the earphone power supply from a 400ma multi-usage AC-DC Adaptor.


 The NE5332 provide more warm but also more detail of for all range sound. The bass enhance but thing that no texture. But no radio translate sound more. 
	

	
	
		
		

		
		
	


	




 After use the super cap box, the bass become more texture (some bass amount), and more detail provided. The speed and control had better that no cap, we can listen almost all detail of piano sound like sit in front of piano that i can not image SR-001 can do that.

 Please caution that i close the system and not plug out the DC supply, it also have 630v electronic excite (
	

	
	
		
		

		
		
	


	




), it hit my heart 
	

	
	
		
		

		
		
	


	




, so that any connect or test must plug out the DC power supply first.


----------



## sclee

Here is the photo of mod sr-001 amp and super cap box


----------



## AudioCats

the output Wima caps are of different size?


----------



## sclee

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_the output Wima caps are of different size?_

 

The output wima both some value but wima have two different size, so that i use the small side on medium.

 The blue one also wima 50v 3700pf bypass.


 After i try install the super cap box, do not found any different between 400ma and 800ma dc adaptor, so that i just use the 400ma.


----------



## AudioCats

Quote:


  Originally Posted by *borisov57* /img/forum/go_quote.gif 
_Maybe someone has sr-001 headphone connector pinout?_

 

the plug: *< -a-b-c-d-e-f- ]*

 a: not connected, serves as a switch so the amp will turn off when the cable is unplugged.

 b: right side outter stator

 c: right side inner stator (toward your ear)

 d: left side inner stator (toward your ear)

 e: bias

 f: left outter stator



 by the way, here is a failure mode of the 001 cable, I suspect it is the common type.(Thanks Catscratch for sending me this cable.) No broken wires, what happened was the bending actions at the plug weakened the silicon insulation, then the pulling (on the cable) caused the silicon to break at the weak point and exposed the copper wires. Since the signal is running at high voltage with little current, any moisture or dust or whatever can kind of short out the wires and cause an intermittern problem.


----------



## sclee

I replayed a pair of OPA2134 and found the current is 400ma
 No heat generated from the opamp but i found most heat for this amp from high voltage.

 The dynamic is better that NE5532, the speed is faster and the sound clearer that NE5532. But the bass amount of NE5532 is more that OPA2134, but may be the OPA2134 is new one and need some time for burn in.

 The OPA2134 have more smooth high frequence response such as the saxphone is not hard. 



 Overall, i found OPA2134 is much better NE5532 when using in this amp.


----------



## AudioCats

Test 2, flea powered portable amp for driving full sized electrostatic phones:

 So I was finally finishing recabling my ESP950 to silver/teflon/silicon, now the wire capacitance is about the same as the Stax ribbon cable's. Before putting on Neutrik 7-pin, I thought..... might as well try it on the 001 and see how it sounds. 






 In this test the 001 board has AD825 and Russian FT-3. Sound is loud enough, plenty of details, but not as juicy so not as realistic as the full sized amp. A bit cold and hard. Will let it run for a few hours and see if anything improves.


----------



## borisov57

Thank you AudioCats for pinout. I would like to roll my own amplifier for Staxes.


----------



## AudioCats

no problem borisov57, please let us know how your amp project goes. I assume it is also a battery-powered portable amp, right?


----------



## borisov57

No, I am thinking of full size home amp. I am very satisfied with sr-001mk2 for portable use. I used SR-80 for that purpose before, but staxes are completly different league for me.I will try amplifier with sr-001 because of absence of full size Staxes and funds for them. Of course, I will let you know, if it will be good.


----------



## chi2

Hi there!

 I've got a SRM-001 MKII (since today early in the morning 
	

	
	
		
		

		
		
	


	




) Great little beast! But it ate a pair of fresh alkalines in no time. That's why I tried some of my NIMH batteries. All of them have been freshly charged. The result leaves me puzzled: Of the six types of NIMH AA batteries only two are working; nonfunctional are among other Sanjo Eneloops and Duracells. The voltage is not different from those accepted by the baby Stax amp. Does anyone have an idea what causes the little amp to refuse some types of rechargable batteries while it happily accepts others? 

 Thank you, chi2.


----------



## AudioCats

it depends on how new your NiMh is. The NiMH deteriorates over time, the average acceptable service life is about 3 year, whether you use it or not (of course, it will get worse faster if you do use it). 

 When you measure the batteries, you measure them outside of the amp, no? that will be a no-load voltage. Once installed and turned on, the amp will ask for a bit of current and the battery voltage will drop. Even for the new batteries, 2x NiMH is already pretty low, if the battery is old the voltage can easily drop below the "no-go" line (when the amp is on) and the amp will give you the red light.....


----------



## chi2

AudioCats,

 Thanks for your reply. Amazingly the never used Eneloops and the still very new Duracells don't work while some old Swissbatteries and a no name type work well. To complicate things even more, I found out that when mixing types of batteries (just to experiment - no standard practise 
	

	
	
		
		

		
		
	


	




) things work if a certain type of battery is in the right bay, but it doesn't work when it's in the left bay. "Not working" actually means that none of the LEDs is on - also the red one stays dark. Could there be some sort a sensor that responds to the surface of the battery as those that are working seem to share a blank metal case??


----------



## borisov57

Hi chi2,

 Did you bought new srm-001mk2 or used one? New ( unmodded unit ) should work for at least 4-6 hours. It draws cca. 300mA from batteries.


----------



## chi2

Quote:


  Originally Posted by *borisov57* /img/forum/go_quote.gif 
_Hi chi2,

 Did you bought new srm-001mk2 or used one? New ( unmodded unit ) should work for at least 4-6 hours. It draws cca. 300mA from batteries._

 

Yes, I have the MKII version. It has a rather impressing sound quality but munches batteries like M&Ms. Thus I'm trying to use accus, but the Sanyo Eneloops especially bought for it don't work at all!?


----------



## borisov57

I mean, did you bought your unit new or used. If you bought it used, it can have different opamps instaled with more current draw. It can eat batteries twice faster than with stock opamp.


----------



## chi2

Oh, I see. Yes, I bought it new, so no energy-hungry modifications (so far 
	

	
	
		
		

		
			





).


----------



## sclee

Quote:


  Originally Posted by *chi2* /img/forum/go_quote.gif 
_Oh, I see. Yes, I bought it new, so no energy-hungry modifications (so far 
	

	
	
		
		

		
		
	


	




)._

 

i know why the NIMI can't be used on sr001, some battery, the polar + metal contact small cone dimension had been large, so that this can't be contact with sr001 plus, the alikline battery mostly have small cone size that NiMH one, so that please try to use small cone size


----------



## chi2

sclee, that's a great idea and a plausible hypothesis. It fits with my observation regarding the dark red LED and the differences between the two bays. I'll check as soon as I get home tonight! Thanks a bunch!


----------



## AudioCats

yeah, if even the red LED was not on, it is probably a contact issue. some NiMH have too large a + tip to reach the battery bay contact.


----------



## chi2

Problem solved. Kudos to sclee and AudioCats! As a matter of fact the Eneloops and Duracells have a wider cone at the + pole that doesn't fit the respective slot in the SRM-001. (In my amp the widths of the + slots in the two battery compartments are slightly different. This is why things worked with a certain type of battery in the outer/right compartment but not in the inner/left one.)
 I guess I'll widen the slot by cutting away 0.5 to 1 mm of plastic on each side. This way batteries with a smaller cone will still work. 

 Thanks a load, chi2


----------



## chi2

With regard to the sleeves of the SR-001 I found out something that might be of interest for some of you. I guess I'm not the only one being somewhat uncomfortable with the original sleeves. After some fiddling they do give me good isolation and a very defined and satisfying bass (no lack of bass here!). But they begin to hurt after an hour or so. I was thinking of going for custom sleeves but wanted to try some existing sleeves first. The silicone sleeves of my Vmoda Vibes - despite of being round - are quite easy to mount. The largest size provides a good fit in the ear. They hurt later and less than the original sleeves and the low frequencies are quite good, too. Actually it's easier for me to get a good fit with them than with the Stax sleeves. I may still go for custom sleeves some day as the fit and feeling of my Livewires is unsurpassed.

 Cheers, chi2


----------



## AudioCats

warning: if you are planning on doing the mods, be aware that digikey # 496-1881-ND is no longer awailable. That is the 0.1uf/630V X2 high voltage power cap. I have yet to find a 0.1uf that is the exact same size (checked mouser and digi-key).


----------



## aeroflot

sorry if i am off topic, but my earspeaker's cable just broke. i have tried to repair it, but now i have humming noise. i was also wondering if it was possible to buy a new cable. Any place that shipps to Europe would be great.


----------



## AudioCats

I think AudioCube and priceJapan will both ship to EU.


----------



## AudioCats

an update on the SFC++ configurations. I have decided to use Hammond aluminum case for battery box, they are easier to work on and are more slim than the plastic one I used before. The trade off is the internal capacity, the aluminum can only hold enough li-ion for 11 hr max.








 and why did I choose a case shorter than the 001? for easy access to the volumn knob.


----------



## AudioCats

Aero class size comparison: Proton-K on the left, Delta-IV on the right (just to give you an idea. no mods yet).


----------



## HeadphoneAddict

11 hours is still nice. And the size keeps it in the jacket pocket/fanny pack range, instead of tranportable/backpack sized.


----------



## gooky

Hey, AudioCats, a quick question. Is there anything I can do about the stiffness of the knob? It doesn't turn very freely, and I wondered if you ever tried to do anything about it.
 I also had some rechargeable batteries (Duracell) that didn't quite fit in the smaller slot. If you apply a little force while fitting it into the positive side, contact is just fine. Just wanted to throw that out to people who considered enlarging the positive terminal...


----------



## AudioCats

Quote:


  Originally Posted by *gooky* /img/forum/go_quote.gif 
_ Is there anything I can do about the stiffness of the knob?_

 


 you can change the knob.... but that will change the "color scheme" 
	

	
	
		
		

		
			





.


----------



## gooky

Right, I guess I wouldn't want to do that...


----------



## ak40ozKevin

Quote:


  Originally Posted by *aeroflot* /img/forum/go_quote.gif 
_sorry if i am off topic, but my earspeaker's cable just broke. i have tried to repair it, but now i have humming noise. i was also wondering if it was possible to buy a new cable. Any place that shipps to Europe would be great._

 

I had to repair my cable and had a problem with humming too. I just redid it and eventually the humming went away. 

 Unfortunately my cable broke again at the plug and I'm still working on fixing that. I really need a continuity tester or multimeter to do it right though.


----------



## oicdn

I got 9 hours non-stop (7 with multiple on/off powering) with a bunch of volume adjusting while using using those Sony Batteries I posted about.

 I logged usage every time I powered her on or used her via the Touch she was attached to. So does that mean the short battery life you're experiencing is due to the mods, or just using those 900mAh batteries?


----------



## AudioCats

If you are using 2600 mAh NimH, 8-10 hours is about right. 

 The mod basically doubles the power consumption, and because two lithiums don't add up to 2500mAH, the play time of a modded system is much lower than a stock amp.

 But you gain SQ with the mod...... need I say more?


----------



## oicdn

Yeah...they're somewhere between 2600 and 3000mAh...

 This mod, is it a subtle difference like the iMod, or is it a huge difference in SQ???? Like leaping from one amp to another?

 Frankly, I'm pretty satisfied with the SQ I have right now, and swore I would leave my portable rig alone forever....but this mod has me curious....


----------



## HeadphoneAddict

Quote:


  Originally Posted by *oicdn* /img/forum/go_quote.gif 
_Yeah...they're somewhere between 2600 and 3000mAh...

 This mod, is it a subtle difference like the iMod, or is it a huge difference in SQ???? Like leaping from one amp to another?

 Frankly, I'm pretty satisfied with the SQ I have right now, and swore I would leave my portable rig alone forever....but this mod has me curious...._

 

It is a huge difference between stock and super fat cat modded 001.


----------



## oicdn

Son of a (&%*&^%%%&&($##%#@.... Just when I thought I was COMPLETE.... Anybody wanna lemme borrow it for a bit to compare? I'm EXTREMELY anxious to hear the difference, but have other things on the "spending list"....


----------



## Nenso

<snip>mod
 lol, it's alright pal. I can lend you my W1000 if you want. Can you tell me which address you want it to be shipped to?


----------



## ak40ozKevin

So I performed surgery on my SR-001 cable. It was almost a disaster due to poor planning on my part. The original issue which I've had twice was that somewhere around the plug one of the 6 cables gets fractured which causes the sound to cut in and out from a low to high volume. 

 So my plan was to slice open the plug along the edge with a razor, cut the cable down a few inches, re-solder the contact points, and re-assemble with some heatshrink over the the thing for safe measure.

 I accomplished this but not without some struggles along the way. Dissecting the plug was simple enough with no glued parts or anything. However when I opened the plug chamber the six separate cables popped out and I had no idea where there original positions were! I resoldered everything anyways which took a few hours since I haven't used a soldering iron since highschool. The cable is so flimsy I just had so much trouble getting clean connections on top of them having to cleanly fit back in the plug chamber.

 What really threw me off and required testing was the order in which these things were in there originally. Everytime I wanted to test a configuration the little contact points would break loose and crap so it took forever to test.

 So there is six contact points on the plug and on the SR-001 driver. It took me a lot of testing that yielded some really weird sounds in instances where I got it wrong. Strange things when signals got mixed with one another. Kinda creepy. Maybe someone already knows this but I will number the contact points on the SR001: 1-6 and the 6 separate wires: A-F. Here's how I matched them up in the end which seems to be working:
 DISREGARD
 1. - Empty plug no wire attached
 2. - A
 3. - C
 4. - D
 5. - B and E (Shared Ground)
 6. - F
 \DISREGARD
 From what I can tell, number 1 simply tells the unit if the headphones are plugged in or not. If you don't put the empty contact pin in that spot the unit won't turn on. This is what initially threw me off.

 It's kinda late and this probably doesn't make much sense to anyone but I can draw a simple diagram later if anyone would find it useful. Or can expand on the process of opening everything.

 EDIT: Nevermind after further listening I don't have it right. Both headphones are receiving both channels so I've been enjoying mono. Back to testing.


----------



## borisov57

Hi ak40ozKevin,

 Look at post 141 on page 15. Maybe you will find it useful. There is pin diagram of sr-001 connector.

 Good luck


----------



## ak40ozKevin

**** that means I had it right all along. I must need to clean up my connections because I bet the sound signal is traveling up the bias or something?


----------



## oicdn

<snip> mod
 In anycase, tog et back on topic, how many others have done this mod either on thier own or through audiocats? What's the battery life like WITHOUT using the external pack at its final stage of mods?


----------



## HeadphoneAddict

<snip> mod
 The SFC runs about 3 hours on a pair of lithium 14500 cells in parallel. I get about 6 hours on some old cheap re-chargable NiMH with my stock SR-001. 

 I'll sometimes use the SFC modded in my car because I can still hear traffic, and I have a 4.5v DC adapter in the car that I use. Most of the time the SFC is at my bedside rig, fed by H140>HR Micro DAC>SR-001 SFC modded. The 3 hour battery life is just too limiting to carry it around as my portable rig.


----------



## AudioCats

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_ The 3 hour battery life is just too limiting to carry it around as my portable rig._

 


 Larry, if you are willing to lose the capability of holding internal batteries (since you are using it as a desktop and in a car, both with external power), do you want a convertion to the SFC ++?


----------



## HeadphoneAddict

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_Larry, if you are willing to lose the capability of holding internal batteries (since you are using it as a desktop and in a car, both with external power), do you want a convertion to the SFC ++? 
	

	
	
		
		

		
			



_

 

Hi there,

 I'll have to go back over the thread to see what that entails. I'd probably like an external battery pack to go with it like the ones you've made that run it for a long time, and it also depends on the cost. You could PM me about this if you want.


----------



## HeadphoneAddict

PS: I do have an unused pair of OPA627AU SOIC laying around here


----------



## AudioCats

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_PS: I do have an unused pair of OPA627AU SOIC laying around here 
	

	
	
		
		

		
		
	


	


_

 

a pair? do you realize the 627, like the 825, are single opamps, it will take FOUR to run the 001 
	

	
	
		
		

		
		
	


	




 but the tiny little step-up power supply in the amp can't handle the 627's current draw anyway....


----------



## HeadphoneAddict

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_a pair? do you realize the 627, like the 825, are single opamps, it will take FOUR to run the 001 
	

	
	
		
		

		
		
	


	




 but the tiny little step-up power supply in the amp can't handle the 627's current draw anyway....
	

	
	
		
		

		
		
	


	


_

 

Okay - guess that's a bust. I even have 4 more OPA627AU, but they are already soldered onto 2:1 adapters for use in "normal" amps.

 I'm off to go study your PM now.


----------



## oicdn

I think an external battery pack that isn't a permanent solution would be cool. i.e. ability to still batteries, but using a battery pack via the jack during things like plane rides or just whenever would be pretty neat. This way you're not LOCKED into having to carry the battery pack.


----------



## ak40ozKevin

**** man after re-doing this cable 20 freaking gatdamn times I've finally discovered what the real problem is. My issue was never a cable issue at all but rather the contact points on the PCB are worn and require you to tilt the plug in at an angle in order to insure that full contact is made with the pins in the cable.

 I wasted a lot of time on this. On the positive side it was educational and i'm a ******* solder master now.

 Can anyone recommend a good conductive circuit repair pen or something?


----------



## AudioCats

Quote:


  Originally Posted by *ak40ozKevin* /img/forum/go_quote.gif 
_I wasted a lot of time on this. On the positive side it was educational and i'm a ******* solder master now.
_

 

*What doesn't kill you, make you stronger! *

 or at least that is what "they" said.....
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *ak40ozKevin* /img/forum/go_quote.gif 
_Can anyone recommend a good conductive circuit repair pen or something_

 

what is gonna happen if the paint wears off after a while, and the little conductive flakes short out the circuit (the connector pins are pretty closely spaced...)?


----------



## ak40ozKevin

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_*What doesn't kill you, make you stronger! *

 or at least that is what "they" said.....
	

	
	
		
		

		
		
	


	





 what is gonna happen if the paint wears off after a while, and the little conductive flakes short out the circuit (the connector pins are pretty closely spaced...)?_

 

You know there was some crossover flakes when I took it apart! They produced popping noises which couldn't be good but it wasn't enough to cause a short apparently since the unit still works. Now the unit works it's just finicky as all hell and I can't really move the plug around too much while listening.

 I guess I could send it off to be repaired but it's grey market and difficult.


----------



## AudioCats

might as well solder the cable wires directly to the circuit board. Much better connection that way.

 detachable 001 connectors are only for people who doesn't solder 
	

	
	
		
		

		
		
	


	




 Think about it, with a full size amp, you have socket and plugs so you can use different phones with the same amp. now the 001.... is there any other phone that can be used with the little amp 
	

	
	
		
		

		
		
	


	




 ? Since there isn't any other phone options and the detachable connection has gone un-reliable, might as well hardwire the cable to the board....


----------



## Victor Chew

Would you recommend new DIY'ers to try the mods?


----------



## moray james

Victor you know what you can and cannot do. Read throught the thread and decide. The unit is at least inexpensive enough that if you blow it up it is not the end of the world to start fresh with a new unit. I am sure people here have vapourized far more expensive units in the name of an upgrade, I know I have. 
 Regarding the plug issue Audio Cat is right you do not want to be painting anything inside of that tightly spaced plug. You might consider rebuilding the plug with copper wire inserts. I think the answer given is the smart one and it makes very good sense. Not to mention the fact that the solid solder connection will sound a lot better than your plug ever did. If you want you could install a connector a few inches along the cord from the unit but I really don't see the point in that. Make sure that you pre-tin the leads before you solder them into the amp and keep your leads short then use a little silicon for strain relief.


----------



## AudioCats

replacing the input and output caps are easy to do, all these parts are through hole mount.

 If you leave the opamps alone, you can do a basic upgrade by replacing the input caps (c1, c2) with BlackGate 47uf NX and BC 0.12uf, then the output caps (c7, c8) with something nicer, say Sonic-1 0.01uf or Sonic-2 0.0091uf, and change the high voltage power reserve (C6) to 0.1uf X2 polyprop......it is easier than making a Cmoy amp.


----------



## ak40ozKevin

So I soldered the cable directly to the pins on the SR-001 driver and it works fine. Seems like a good enough idea however putting the case back on with the plug housing and LED cover thing isn't possible now. So I sawed a bit of it off so I could fit it all in. Now I just have a problem with strain relief. 

 With the old plug the the plastic housing clamped down on the cable so that it wouldn't jostle the internal cabling if you pulled on the cable outside the plug housing.

 I guess I'll fiddle around with putting the plastic plug piece over the wires and see if it will fit and if I can clamp it down that way unless anyone wants to throw any ideas at me.


----------



## AudioCats

The new "top jumper, long box" battery pack design, with 8x 14500 inside. The advantage of this top-jumper arrangement: the volumn knob is forward and elevated so it is easy to turn, like in the previous "short box rear jumper" design; while the effective overall length is only slightly longer (the rear jumper connector in a short box design sticks out quite a bit); and, needless to say, the total capacity is up by 33%


----------



## HeadphoneAddict

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_





 The new "top jumper, long box" battery pack design, with 8x 14500 inside. The advantage of this top-jumper arrangement: the volumn knob is forward and elevated so it is easy to turn, like in the previous "short box rear jumper" design; while the effective overall length is only slightly longer (the rear jumper connector in a short box design sticks out quite a bit); and, needless to say, the total capacity is up by 33% 
	

	
	
		
		

		
		
	


	


_

 

Great, now I don't know what to do again...

 ...I'm still leaning towards the 6-cell short box with fixed/attached pigtail...


----------



## ak40ozKevin

I managed to get the pieces permanently soldered and secured by putting the plastic plug piece over everything so it still looks like a removable plug but it's not! 

 I'm just happy to have a portable stax system working again!

 AudioCats: Those modded units are intense but very clean looking. I'd love to hear those sometime just to hear what I'm missing out on by passing up the mods. Instead I might just try to source a SR005 cable to use with my 252A to hear how these guys scale.


----------



## AudioCats

C-cell battery box idea ( revisit):

















 The plus: NimH C-cells are widely available, can be charged externally, capacity is usually around 5000mAh. 
 Of course, normal dry-cell or Alkaline batteries can also be used 
	

	
	
		
		

		
		
	


	




 The minus: the box is not particularly small. And it is recommanded to use a dummy cell when using alkalines (other-wise the total voltage might be a little too high).


----------



## Victor Chew

What kind of reasonable usage time can you get out of the battery pack?

 I am tempted to try out the mod and greatly appreciate the dangers or vapourising the unit completely. Thing about the caps, is that, I intend to use the soni caps, but direction wise can get tricky, doesn't it? On my external caps after my imod I find that my 1uF, 3.3uF and 4.7uF is better the other way round. Its easy for the caps as one only has to swop the in for out, but in the case of the 001, soldering and unsoldering will make my head spin and not to meantion that as a smoker my hands do shiver a bit!!! Ha! My wife always childs at me remarking that my shivering is due to the smoke!!!

 Has anyone tried the directional change of the caps impacting the change in sound yet? Believe me, the difference is not minimal.


----------



## AudioCats

yes film caps are still directional. Using it the normal way gives better over all sound (the red connects to the DC+ --- you will need to use a meter to determine the DC components polarity first, of course.). 

 In a Sonic cap, the "S" end is the "+" lead. See my previous mod pictures for details of cap orientation.


----------



## Victor Chew

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_yes film caps are still directional. Using it the normal way gives better over all sound (the red connects to the DC+ --- you will need to use a meter to determine the DC components polarity first, of course.). 

 In a Sonic cap, the "S" end is the "+" lead. See my previous mod pictures for details of cap orientation._

 

When put in the suppositly correct direction, I find that the sound is out of phase, but the other way round the sound just comes together. Initially, I thought that it was because of the need for extended burn in. Even after that, there was no change. I guess, I would just have to go with your recommendations and take it from there. Tks.


----------



## AudioCats

connecting the caps the other way around give a impressive mid range, a sense of "clarity" and sharpness, especially good for vocal. But that is where the benefits end. To my ears, with the reverse connection almost everything else suffers, the sense of clarity and sharp details is gained at expense of losing other frequencies. It is great if you just want human voice to stand out, though.

 That was why I said "_over all sound_".....


----------



## Victor Chew

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_connecting the caps the other way around give a impressive mid range, a sense of "clarity" and sharpness, especially good for vocal. But that is where the benefits end. To my ears, with the reverse connection almost everything else suffers, the sense of clarity and sharp details is gained at expense of losing other frequencies. It is great if you just want human voice to stand out, though.

 That was why I said "over all sound"....._

 

Thanks. I will go with your recommendations.


----------



## AudioCats

victor, that was "to my ears", please do try both connections in your set up. Also, you might want to do the experiment with the power source you plan to use. AC adaptor and batteries do sound different, there is no absolute winner and you can adjust the input/output cap combination to get better overall sound with a given power source. If you want to use Li-ion battery pack, the test needs to be done with the battery protection board installed, it does affect the sound. yes the little 001's are that unforgiving


----------



## Victor Chew

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_victor, that was "to my ears", please do try both connections in your set up. Also, you might want to do the experiment with the power source you plan to use. AC adaptor and batteries do sound different, there is no absolute winner and you can adjust the input/output cap combination to get better overall sound with a given power source. If you want to use Li-ion battery pack, the test needs to be done with the battery protection board installed, it does affect the sound. yes the little 001's are that unforgiving 
	

	
	
		
		

		
		
	


	


_

 

Thanks audiocats. As a basic structure, I will start off with the normal direction first. Then perhaps, if the sound is still not "ok" after say, 200 to 300 hours of burning in, then I will swop them around. As for the power when you say"AC adaptor and batteries do sound different", do you mean the batteries sound better to you? In portable setups, generally speaking adapters often produce all kinds of funny noises that gets fed into the system.


----------



## AudioCats

yes the _ unprotected _ batteries sounds the best 
	

	
	
		
		

		
		
	


	




 somehow the protection board adds extra "coldness", so if you are trying to figure out what cap combo works best for a li-ion pack, the protection board needs to be installed during the test (since it will be there during normal use).


----------



## AudioCats

There will soon be a new class, the _Mighty-Mini_. It is basically a input/output and power capacitor upgrade like some of you have done, except I will try real boutique caps (VitQ, Sonic-1, Kimber for input; Cardas, Sonic-1/2, Auri, Kimber, AudioCap Theta for output).

 The opamps will remain the stock 062L, therefore the SQ of this mini-mod will not be as nice as the higher level mods such as FC or SFC/++. Then you might ask why do I want to keep the low performence 062L opamp..... the reason is: power consumption. But, it is not what you might have thought: I am keeping the 062L, so the opamp stage will consum as little power as possible, so most all of the power that little step-up transformer generates can go to the high voltage rail for the output stage. This way the output stage can better drive pro-biased headphones (Lambad pros, ESP950s, etc). I am pretty sure when used with large headphones the 001 amp will suck a lot more battery juice than with in-ear phones, so I don't expect as long a run time as a stock SRS-001 (unmodified amp driving baby stax in-ear's)

 Because the 062L is a pretty low performence opamp, real fancy boutique caps have to be used to try to "cover up" the problems. I don't think it will ever sound as nice as the higher level mods, but it could have as much output power as a top level Saturn-VIII (the VIII uses tri-voltage battery packs, therefore not very practical for true portable use). 

 The goal of the Mighty-mini mod is to try to bring the 001's SQ to close to the SRM-252 level, and able to drive full size phones ok (it still won't have the full power of the 252 though), while still be a pocket size amp so it can be used on-the-go. 

 We will see how it turns out


----------



## Victor Chew

I think I will just do the basic first. Swopping the caps will be a no brainer for me. Upgrading the power supply section and so on will be the next stage. I will use your pictures as my schematics.


----------



## AudioCats

Mighty-mini testing. The winning combo's are.......

 VitQ 1uf/100v for input, and Kimber 0.01uf for output.

 or, Sonic-I 1.5uf/200V for input, and Cardas 0.01uf for output.

 The overall SQ level of both combinations are about the same, with the Sonic/Cardas a little bit creamier and with a slightly wider sound stage. 

 As you can see in the photo, I have tested quite some cap combo's. I don't want to go into details on how the other combo's did, lets just say they were not very "listenable".

 two special notes:
 * the VitQ's I tested were the 96P series 1uf/100V, they might be too large to be fitted into the battery compartment.
 * The absolute maximum allowable size for an output cap (that is if you can do *all* the tricks to make it fit), is about 0.3" (d) x 0.75" (L). Now if you go on-line and check out the spec for Cardas 0.01uf, the spec shows a 0.33" diameter which will be too large. However the four Cardas I have all measured 0.28" in diameter. I got them from Soniccraft. Not sure if cardas has recently changed the design.

 And NO, even with the best cap combo the mini mod is still not quite where the FC mod is. But not too far from it.


----------



## Victor Chew

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_





 Mighty-mini testing. The winning combo's are.......

 VitQ 1uf/100v for input, and Kimber 0.01uf for output.

 or, Sonic-I 1.5uf/200V for input, and Cardas 0.01uf for output.

 The overall SQ level of both combinations are about the same, with the Sonic/Cardas a little bit creamier and with a slightly wider sound stage. 

 As you can see in the photo, I have tested quite some cap combo's. I don't want to go into details on how the other combo's did, lets just say they were not very "listenable".

 two special notes:
 * the VitQ's I tested were the 96P series 1uf/100V, they might be too large to be fitted into the battery compartment.
 * The absolute maximum allowable size for an output cap (that is if you can do *all* the tricks to make it fit), is about 0.3" (d) x 0.75" (L). Now if you go on-line and check out the spec for Cardas 0.01uf, the spec shows a 0.33" diameter which will be too large. However the four Cardas I have all measured 0.28" in diameter. I got them from Soniccraft. Not sure if cardas has recently changed the design.

 And NO, even with the best cap combo the mini mod is still not quite where the FC mod is. But not too far from it._

 

Awsome. Will you write a review on it? Perhaps, for the changes after each stage of mod. I would be very proud of the work if I were in your shoes.


----------



## AudioCats

I will post a few more knownly-good cap combo's when I have the time this weekend.

_Mighty-mini_ final cap combination...... it turned out to be the same as the SFC++, Auri/BG-NX (or VitQ) for input, and Sonic-1 for output. Except the output Sonic-1's here will be two 0.015uf parallal together to form a 0.03uf. Fitting them into the case will be a major pain-in-the-Ace but likely still doable. Bass is surprisingly strong from my ESP950. The final sound of the mighty-mini driving the ESP950 is close to the level of a SFC driving 001's, mainly because the 950's are much better phones. 

 I personally like the sound of Cardas output better, but the smaller (0.01uf) value of Cardas doesn't allow the bass to go very deep. 







 Current draw is 270mA. A LOD/battery pack combo box (which I am planning to do) should be able to run it for 12 hours. If the "001 narrow slot-> Lambda-pro wide" cable adaptation issue gets worked out, the mighty-mini can be a convenient pocket amp for driving Gamma-pro and Lambda-pro's.


----------



## krmathis

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_http://i191.photobucket.com/albums/z5/audiocats/IMGP1826.jpg

 Mighty-mini testing. The winning combo's are.......

 VitQ 1uf/100v for input, and Kimber 0.01uf for output.

 or, Sonic-I 1.5uf/200V for input, and Cardas 0.01uf for output.

 The overall SQ level of both combinations are about the same, with the Sonic/Cardas a little bit creamier and with a slightly wider sound stage. 

 As you can see in the photo, I have tested quite some cap combo's. I don't want to go into details on how the other combo's did, lets just say they were not very "listenable".

 two special notes:
 * the VitQ's I tested were the 96P series 1uf/100V, they might be too large to be fitted into the battery compartment.
 * The absolute maximum allowable size for an output cap (that is if you can do *all* the tricks to make it fit), is about 0.3" (d) x 0.75" (L). Now if you go on-line and check out the spec for Cardas 0.01uf, the spec shows a 0.33" diameter which will be too large. However the four Cardas I have all measured 0.28" in diameter. I got them from Soniccraft. Not sure if cardas has recently changed the design.

 And NO, even with the best cap combo the mini mod is still not quite where the FC mod is. But not too far from it._

 

That seems like a well modified SRM-001. 
	

	
	
		
		

		
			




 Well done!


----------



## AudioCats

Recommanded input/output cap combo's, for a basic cap upgrade
 --- assuming you are only changing the input and output caps, not replacing the stock opamp, and not shorting out R33/34/35. 
 --- assuming the little amp is pushing a pair of baby stax. 
 --- assuming you are willing to put the input caps into the battery bay, or there won't be enough room. Therefore an external power source is a must.( If you plan to keep the battery bay, see the end of this post for cap recommandation.)

 a* VitQ input, Cardas output -- very full warm sound, no hardness, wide stage, but a little too thick. The speed problem of 062L is not too obvious.

 b* VitQ input, Kimber output -- good. A little cold. Good speed (which only means it hides the problem well).

 c* VitQ input, Sonic-1 output -- good, a little hard. Showes speed problem, obvious.

 d* Sonic-1 in, Sonic-1 out -- good sharpness, a little hard. Obvious speed problem.

 e* Sonic-1 in, Cardas out -- not as thick as the VitQ/Cardas. basically no hardness. kind of showes the speed problem.

 f* Kimber in, Sonic-1 out -- good clarity, good sharpness, hides the speed problem pretty well, but bass is too light.

 g* Auri 0.22uf by-passing BlackGate NX47uf for input, Cardas as output -- about the best there is without changing the opamp.

 h* Auri 0.22uf by-passing NX47uf for input, Auri as output -- not quite as good as the one above, but close. As always, Auri out gives a fatigue-free sound, might not be very impressive but good for all-day listening. Now whether your ear canals can handle the baby stax for that long is another question.

 i* Auri 0.22uf by-passing NX47uf for input, Sonic-1 as output -- good but a little hard.

 The speed problem is from the opamp so it is always there, just whether you will notice it right away. For driving baby stax, my preference is g > h > i & e > a & b. 


 If you have to keep the battery bay and use the internal batteries, the best combo will probably be BC 0.12uf by-passing NX 47uf blackgates for input; and Auri or Cardas for output, with Auri a little on the hard side and Cardas slightly thick. 


 My Proton-K will get done this holiday weekend, and it is about as far as I will go for 001 modding. I no longer have the willingness to do a Saturn-VIII "just because I can", I much rather put the money toward my SRM-1 (non-MK2, non-pro) upgrade.


----------



## AudioCats

By the way, somebody should test the 0.01uf Audiocap theta and write a report. Theta's are very promising caps.


----------



## webbie64

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_My Proton-K will get done this holiday weekend, and it is about as far as I will go for 001 modding. I no longer have the willingness to do a Saturn-VIII "just because I can", I much rather put the money toward my SRM-1 (non-MK2, non-pro) upgrade._

 

I, and I'm sure many others, cannot thank you enough for the many hours of work you have put into this Mod thread, as well as the Mods themselves.

 I thoroughly enjoy both a FC and an SFC and appreciate your research and assistance to me and those who have helped get mine together.

 May your SRM-1 upgrade go smoothly and easilly for you, Audiocats.


----------



## Victor Chew

Quote:


  Originally Posted by *webbie64* /img/forum/go_quote.gif 
_I, and I'm sure many others, cannot thank you enough for the many hours of work you have put into this Mod thread, as well as the Mods themselves.

 I thoroughly enjoy both a FC and an SFC and appreciate your research and assistance to me and those who have helped get mine together.

 May your SRM-1 upgrade go smoothly and easilly for you, Audiocats._

 

Agreed. Audiocats has been extremely generous with both his ideas on new journeys and answers to questions (ie. my silly questions). Anything is so much more enjoyable when you are not doing it alone!!!


----------



## AudioCats

Thanks, good luck to you guys too.



 Just in case I might get lucky..... *WTB*, a broken 001 amp or a partially working 001 system. Please PM me if you have one laying around collectiong dust.


----------



## Spasticteapot

Does anyone have frequency response specs on these? 

 Perhaps a comparison to some high-end IEMs?


----------



## AudioCats

Catscratch's review on SFC++ (that amp belongs to Morphsci.)


----------



## HeadphoneAddict

I can say the SuperFatCat or stock SR-001 bass is not as flat down to 25Hz or even 30Hz as my Livewires IEM, but the treble is definitely more extended when you get past 12Khz with the SFC.

 The SuperFatCat modded SR-001 is good enough to be your only Stat if you were on a budget. It could also be your only IEM if you didn't need isolation, or don't mind carrying an amp (or battery pack) with you all the time. In my case, it makes a perfect car/driving IEM because I can hear traffic if needed (and sirens), and I can plug it into my 4.5v cigarette lighter adapter. I actually use it more often at my bedside for listening in bed and in case I fall asleep. I haven't powered up the DV33i tube at my bedside in weeks, and only listen to the SuperFatCat in bed.


----------



## AudioCats

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_it makes a perfect car/driving IEM because I can hear traffic if needed (and sirens), ._

 






 dude, that is crazy.....


----------



## sclee

I ordered 2pcs AD8620, should be better that AD8599 and use lower current. 
 Is the Opamp power supply section don't provide more that +/-12V so that i can safety use the AD8620 ?


----------



## AudioCats

Try using 220 ohm resistors to replace R34/35 (instead of shorting), and measure the +/- supply voltage. you will likely have to go to lower value, possibly 47 ohm or so, but 220 is a good start. 

 Let us know how they sound and what input/output caps they prefer.


----------



## borisov57

AD8620 looks promising. I would suggest, that you measure op-amp voltage before R34/35 resistor with maximum supply voltage ( external supply or Li-ion ). It will most likely be +/-15V. Than you can adjust R34/35 for new current draw of AD8620 ( 4x 2.5mA ), so that op-amp will see only +/-12V.

 Good luck!


----------



## sclee

Thank you for borisov57 and AudioCats informations.

 I installed two AD8620AR, i tested with following and overall current draw is:

 Short R35/R34 15V 360ma
 R35/R34 with 220ohm 12V 345ma
 R35/R34 with 440ohm 9.1V (the stax's default SMD resistance) 320ma

 I will discuss the sound after run more hours.


----------



## borisov57

Great sclee, I will try that one day. I bet it sounds great.


----------



## sclee

After running some hour 30hr+, i believe AD8620AR is the best solution for SR-001 upgrade, i don't know how about AD8599, but AD8620 only need +/-16V provide very good sound and low voltage run for longer time on battery. 
 If the AD8599 warmer that AD8620, i thing AD8620 should better, because i thing this also have a slighly much more warm compare as OPA2134.


 We just added a 220ohm parellel connect to SMD 440ohm resistance, 160ohm equ. and provide +/-24V power supply, and i also short test on +/-30V status, also i tested on 440 ohm +/-16V and added R33 +/-10V

 +/-10V sorry can not be used, crack and small sound happen, no enough voltage supply to opamp

 AD8620 work well on +/-16V, +/-24V and +/-30V(Short time), but different voltage have different sound product. Normally higher voltage provide better sound, sorry about this theory don't apply on here. The best solution should use lower power supply, i suggest +/-16V.

 The AD8620 is a warm opamp, when you increase the voltage, the AD8620 come more warm, very balance on +/-16V, mid-range (vocal) is very smooth, clear and not too hard and warm.

 Second, when voltage increase, bass increase because longer bass time product but quality reduce, on +/-16V the bass is very solid and enough strong, on +/-30V bass become longer time and slightly higher +/-24V between two.

 But the most important point is, when increase the voltage, no more detail produce but the diffiusion increase, mean that confusion, the headphone can not control very complex or dynamic music, also not smooth enough on such violin. On +/-16V the AD8620 with SR001 can control almost everything enviroment, not even how fast the music is. I thing the reason is AD8620 have very high speed, so that audio signal don't need full power of AD8620, but running on lower voltage, the accuracy will improve so that diffusion reduce to very lower level to produce better sound.

 AD8620AR provide very natual and speed to SR001, you believe when SR001 play rock music and you can very clear listen every rhythm very correctly. The sound is very smooth and good dynamic but not too much. Although i thing the sound have slightly warm on midrange vocal, but i thing this much much better that OPA2134.

 We use WIMA redbox for all high voltage output, and use BG bi-polar and EVOX cap on input.


----------



## sclee

I change output cap to 4x Auricap 0.01uf 600v, need so much time for fit inside of the box because we need remain the battery room for portable use.

 We need sometime for run the cap, but at least this more transparent and dynamic .


----------



## AudioCats

still looking for a bad 001 amp as test board (don't want to use my like-new board to do the tests anymore).
 Now I am also looking for bad cable. If I can find a bad amp/bad cable system it will be nice.

 here are the official WTB/FS ads:
WTB bad 001 amp/system, IC excellent 001 cable/wtb bad 001 cable


 I think I will start a "SRM-001 extreme Mod" thread sometime soon, since my mods from now on (if there is more mods) will all have "booster pack" and are no longer tiny little pocket amps 
	

	
	
		
		

		
			





 Have fun


----------



## antonyfirst

So, will we ever see a SRM-001 that outperforms the SRM-717 or Blue Hawaii?


----------



## AudioCats

That is not possible. 

 The SQ can get pretty close to the T1 though (when driving the 001 phones). Unfortunatly the final price is also pretty close to a T1.


----------



## AudioCats

one note: if you are not shorting out R33/34/35, the c17/c18 caps shoould have at least 25v voltage rating. 

 16V caps will work fine If R33/34/35 are all shorted.


----------



## AudioCats

Caution: Pay extra attention to the Q15's temperature. Add adaquate heatsink to prevent it from overheating, add external heatsink if necessary. Try not to use a modded amp in a warm spot (in a pouch, under the sun etc). I have just encounted the first Q15 failure, though the amp is of a early version with different transistors than the current MKII.


----------



## luvdunhill

I have a new baby-Stax incoming, time to start planning the mods! I'd like to start with the battery. I think the protection circuit is important to have in the battery, so is there a recommended part number at this point?


----------



## luvdunhill

almighty. I finally found some good choices. The protected AW cells are 1.2mm shorter than the UltraFire/UltraTrust options. I have a pair of those coming, and a pair of the AW unprotected, as well as a "dummy" AA. I'll let you guys know how they fit. Am I right in assuming that the stock low battery indicator will suffice for under-voltage protection? I'm planning on trying the dummy + protected first and then rigging the 2 bays to be in parallel, per the thread recommendation.


----------



## AudioCats

I think all the 3.7v protector boards should work. However the red light itself might not be a good indicator of low voltage for Li-ion, it is probably not triggering at the right voltage. most protector boards triggers at 2.5V, while if you use two Nimh in a stock 001 it will run quite a while before the red light turns on, and the NimH's are pretty low voltage batteries to start with (1.35v when full I think), so I would guess the red light probably trigger at lower than 2.5v? can anybody confirm the red light's trigger voltage?


----------



## borisov57

Hello,

 My guess is, after using NiMh and Li-Ion batteries, that red lite is current or maybe voltage from secondary winding triggered. I forgot numbers, but it shuts down amplifier at higher voltage, when amp is powered from Li-ion than when is powered from NiMh. I am using unprotected UltraFire Li-Ions again. They sound a bit better than protected ones. I will leave batteries run until red light starts and I will report voltage on Li-ions. But that will be tomorrow, because I am using Toshiba opamp.


----------



## AudioCats

the red light triggers off the primary side. There is no feedback from the secondary side at all (it does use the secondary voltage to run the LED's though).

 yes unprotected cells do sound a little better 
	

	
	
		
		

		
		
	


	




 but then you will need to constantly monitor the light status


----------



## luvdunhill

AudioCats:

 Can you give a recommended size (diameter and length/height) for the spot where you're putting the .01uF Sonic Caps and the 2 low voltage electrolytic in the Pi filter? Also, can you either point the location for the Sonic Caps out in Kevin's schematic, or give a reasonable voltage rating (i.e. > 200V)?

 Thanks!


----------



## AudioCats

output caps have to be at least 600v. the high voltage rail is about 550V, and the stock caps are all 630v. 
 For the max allowable output cap size (physical size), see the info on the "mini-mighty" mod a few pages back. 
 the +/- caps has to be shorter than 8mm if I remembered right. diameter can not be larger than 8mm. 

 Now, for the opamps, due to the heat generated by the Q15, if you are not using an external heatsink it is safer to use 8620. The AD8599 runs hotter. I still think the 8599 is the way to go and the modded amp should be ok if used in open air (uncovered). however I am already in the process of reworking my previous mods by adding an aluminum decal which also serves as the external heatsink, to make them at least pocket-proof.


----------



## borisov57

Hello,

 My amplifier trigger red light and shuts down at a moment, when unprotected Li-ions are at 2.6V. Li-ion voltage rises after I take them out of an amplifier to 2.9V after a few minutes. Usually I do not wait until the red light turns on. When batteries are close to be empty, amp turns on quicker then with full charged batteries and that is the moment for the charger.

 I do not know for NiMh, I have battery compartment wired to parallel, but I can not imagine, that they would be cut off at 2.6V. After all, they are nominally 1.2V.


----------



## luvdunhill

boris:

 thank you for the info. This is very helpful.

 AudioCats: got it. 0.3" (d) x 0.75" (L). Seems the 0.3" is a hard requirements, but what about the length? Could we fit 1.0" length in there?


----------



## AudioCats

actually the 0.3" is not the absolute max it can go, I think the Auri 0.01uf is a little larger than that an still can be fitted in. The 0.75 length on the otherhand is absolute max you can go, unless you do major rearrangement on the output transistor orientations. And even with that it still might not give you the 1" clearence.


----------



## luvdunhill

well, a bunch of capacitors arrived this week and I've been playing around. I'm hearing a lot of variance in the four capacitors used for output coupling. I tried the Sonic Caps, AudioCap TFT, and Reliable RT, and Relcap RTE. The most neutral caps were definitely the TFT, no question about it. If I was going to use this connected to a $5k source, I'd go with these. Very resolving and lots of bandwidth. Bass was full and tight, not bloated. Second was the RTE. Not as much resolution, more more liquid as you'd expect from the 'styrene. I'm probably going to go with these, as they sound a bit more forgiving and have a very nice balanced between detail and liquidity. The other two caps were more of a personal flavoring than anything. The Sonic Caps are a nice all around performer as well, and offer a hint of what the TFT does. I'd say my main issue is things some a bit more distant and grainy in comparison. I had around 100 break-in on each cap, so things could probably change even more (for better or worse).

 I really haven't found a good cap for the middle position. I realize people are using X2 probably to get more capacitance in the space alloted. Has anyone tried the Wima polyester? Any other recommendations here? I'm going to have to move the 'lytics to fit in the fourth cap output coupling cap, and decided to go ahead and double to capacity there.


----------



## AudioCats

finally, somebody is useing the TFT! 
	

	
	
		
		

		
			





 where did you get them from, PCX? 

 teflon is by far the best I have tried, but they are either too huge (the FT-3's I was using) or too expensive (TFT 0.01uf is $30 a pop, no? that is $120 for 4, ouch.... I feel for your wallet). Are you recasing the amp?


----------



## luvdunhill

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_finally, somebody is useing the TFT! 
	

	
	
		
		

		
		
	


	




 where did you get them from, PCX? 

 teflon is by far the best I have tried, but they are either too huge (the FT-3's I was using) or too expensive (TFT 0.01uf is $30 a pop, no? that is $120 for 4, ouch.... I feel for your wallet). Are you recasing the amp?_

 

no, my goal is to keep the current form factor. I purchased them from Percy. I like the FT-3 as well and even better are the Russia mica capacitors. They are way to large though. You should try the RTE, I think they are very nice (though the lead gymnastics are interesting to get them to fit).

 I need to work on the X2 capacitor spot next, haven't really nailed that one down, still using stock capacitor. I have some Wina polyester caps coming, as Mouser didn't have any X2 that were rated high enough and would fit. I'm assuming you had this problem as well 
	

	
	
		
		

		
		
	


	




 I may try the TFT on the input, and just eliminate the other coupling capacitors... we'll see.


----------



## AudioCats

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_ You should try the RTE, I think they are very nice (though the lead gymnastics are interesting to get them to fit).._

 

I wanted to, I actually placed the order before but soniccraft told me they didn't have enough in stock (I suppose they did have some but not 4).



  Quote:


 as Mouser didn't have any X2 that were rated high enough and would fit. I'm assuming you had this problem as well 
	

	
	
		
		

		
		
	


	




. 
 

not sure about mouser, but the digikey X2's mentioned in my previous post were all 305V~/ 760vDC, I would expect all X2's have the same spec?


 By the way, you are using 0.01uf TFT, right? how long is it? PCX spec shows 0.75", percy spec shows 1"


----------



## luvdunhill

oops, sorry didn't notice your post. The caps are around 0.7" long, but there could very well be two versions of the cap out there. Best to ask before ordering.

 I've been playing a lot with the remaining C6 cap. I can hear a lot of difference in this position.. I think it's very important. I tried up to 0.3uF and didn't like the sound as the bass was tubby and not well-defined. To me, the best sounding caps are metalized polyester... I think the minimum needed here is probably 68nF and I really preferred double this amount. Any more capacitance and things started sounding unnatural to me. Specifically, I like the Wima MKS 4 / 630 VDC, compared to Panasonic, Epcos, Evox, and the stock cap.


----------



## lacrossebowe8

I recieved my srm-001 today and so far it sounds pretty good.

 I have read through the thread and am still confused as to what batteries would work best in my situation. I tried some rechargeable duracells that I had and the amp did not even show the red light. So I am looking for some rechargeables that will last a while and sound good. I am not sure how I would do the parallel battery mod but have two large capacity batteries would be nice.


----------



## luvdunhill

Quote:


  Originally Posted by *lacrossebowe8* /img/forum/go_quote.gif 
_I recieved my srm-001 today and so far it sounds pretty good.

 I have read through the thread and am still confused as to what batteries would work best in my situation. I tried some rechargeable duracells that I had and the amp did not even show the red light. So I am looking for some rechargeables that will last a while and sound good. I am not sure how I would do the parallel battery mod but have two large capacity batteries would be nice._

 

I have a pair of unprotected lithium batteries I could sell you that fit, but you'll need a charger...


----------



## lacrossebowe8

I may be interested, what type and size are they? How do you do the parallel battery bay mod?


----------



## luvdunhill

Quote:


  Originally Posted by *lacrossebowe8* /img/forum/go_quote.gif 
_I may be interested, what type and size are they? How do you do the parallel battery bay mod?_

 

The brand is DLG and size is 14500. I'd like $8 shipped for the pair. Once you open up the amp, you'll see how to do the parallel battery mod, it's quite obvious.


----------



## lacrossebowe8

what capacity are they and voltage and age?


----------



## luvdunhill

Quote:


  Originally Posted by *lacrossebowe8* /img/forum/go_quote.gif 
_what capacity are they and voltage and age?_

 

3.7v/700mAh and brand new... never been used.


----------



## lacrossebowe8

what charger could I use for them?


----------



## luvdunhill

Quote:


  Originally Posted by *lacrossebowe8* /img/forum/go_quote.gif 
_what charger could I use for them?_

 

don't know. i built my own. If you want them, please PM me, otherwise...


----------



## luvdunhill

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_Caution: Pay extra attention to the Q15's temperature. Add adaquate heatsink to prevent it from overheating, add external heatsink if necessary. Try not to use a modded amp in a warm spot (in a pouch, under the sun etc). I have just encounted the first Q15 failure, though the amp is of a early version with different transistors than the current MKII._

 

any recommended heat sink patches? the link you posted in reference to this is dead, so I couldn't see the kit you were referring too..

 oh and also, do you know the resistor size and power rating of R35/R34?


----------



## luvdunhill

sounding great!


----------



## AudioCats

hmmmm, not sure where to find small patches, digikey has the big ones but they are way big @ $70 per sheet.

 hehehe, so the RTE's do fit. What op-amp are you using?


----------



## luvdunhill

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_hmmmm, not sure where to find small patches, digikey has the big ones but they are way big @ $70 per sheet.

 hehehe, so the RTE's do fit. What op-amp are you using?_

 

yeah, I've seen the big ones at Digikey... I'm probably going to see if I can get a sample 
	

	
	
		
		

		
		
	


	




 Right now, I'm using LMH6642MA. I tried the same Analog opamps as you did, as well as the AD8610. For some reason, I cannot fault the LMH6642MA at this point, and battery life is good, so I just left it in.

 With the RTE, you just have to be very creative with the lead bending. With the one closest to the back of the board, you need to desolder one of the HV caps and sort of tilt it a bit. You also have to file down one of the supports at the front of the case.

 I'd love to try another headphone with this amp, so either finding a cable to hack up or making an adapter is my next goal, as well as a small shunt regulated DC supply.


----------



## borisov57

Hello,

 I just changed Toshiba opamps for OPA827. Sound has changed a lot. Whole spectrum is cleaner with more details in midrange and sound is more 3D. Notes decays longer.


----------



## HeadphoneAddict

With the AD8599 and Super Fat Cat ++ (requiring external battery pack due to caps in the battery bay), the SR-001 sounds as good as SR-003 on a good desktop amp. So far I have been very impressed after another 500 hours of burn-in (just in case). It is much better extended at both ends of the spectrum than stock, without the midrange hump. And, it is smoother and more refined than the previous SFC which still allowed 2 parallel Lithium batteries inside. Bravo!


----------



## borisov57

AD8599 is great op-amp, but I did not like it too much in SR-001. I had it in amp for only one day. Maybe I should give it another chance and some more time to settle in. But OPA827 sounds great from first second. Low level detail and ambience retrieval is unbelievable.


----------



## sclee

No updated on the thread long time.

 I bought a UM3 try to replace SR001 but the quality of moded sr001 is better that um3 much more.


 About the power.

 I bought 2 pcs Ultrafire Li ion battery, supply to sr001, compare as power supply and Li ion battery. 

 The Power supply with large cap and good buffer cap should better that Li ion.

 Power supply:

 1. Must non-regulator power supply. At least 400ma output
 2. set 4.5v with one 1W diode
 3. 2 Elna Audio 3600uf Cap, one WIMA Black 0.15uf Cap and one 0.1uf MIT Multicap 

 The output voltage of power supply is 3.25V

 The bass quality and speed will better that Li-ion, but Li-ion slightly more clear that power supply. 

 Mobility of Power supply is very poor, so that i want to try big Li-ion supply with good buffer cap.

 I could like to found High volume Li-ion batterys and recharge IC, build a dual power battery box with at least 15hour run time.


----------



## borisov57

I guess we need something better than unregulated supply. Something like Jung regulator with low Zout and low noise.

 Sclee:
 I have listened to UM2 once, but for me it is not even close to SR-001.


----------



## EFN

I have a virgin SRM driver heading my way......can't wait to start modding them


----------



## EFN

Almost done. Just waiting for a few more caps to arrive.











 Still a bit of work on the C6


----------



## borisov57

Wow, that looks cool. What are those yellow caps? Will they fit in enclosure?


----------



## EFN

Quote:


  Originally Posted by *borisov57* /img/forum/go_quote.gif 
_Wow, that looks cool. What are those yellow caps? Will they fit in enclosure?_

 

The yellow caps are custom fabricated by Octave Audio Malaysia. Yes they barely fit the enclosure. But I am afraid I will run out of space very soon once the C6 caps are being worked into them.

 Cheers


----------



## fishpatrol

I may just not have found it, but has anyone done a write up comparing a modded SR-001 with a stock SR-005?


----------



## HeadphoneAddict

catscratch did something similar with a modded SR-001 and a SR-003 on a SRM-3xx series amp, and I chimed in with my SR-003 on an SRM-1 Mk2 Pro.

Review: AudioCats-modded Stax SR-001 MkII, vs Stock SR-001 and SRM-313/SR-003 - Head-Fi: Covering Headphones, Earphones and Portable Audio

 Since his review where I commented, I have had mine taken up to the next level, and it is now better than SR-003 on any amp I still have except for my Woo GES which beats it.


----------



## AudioCats

Quote:


  Originally Posted by *EFN* /img/forum/go_quote.gif 
_Almost done. Just waiting for a few more caps to arrive.






_

 

Judging by the reloaction of the input jack, I supposed you are re-casing it? 

 if so, might as well add a regular 5-pin socket, they are not that big...


----------



## AudioCats

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_I'd love to try another headphone with this amp, so either finding a cable to hack up or making an adapter is my next goal, *as well as a small shunt regulated DC supply*._

 

any updates on that DC supply? 

 a modded 001 can drive the Jade and ESP10 ok, the sound is very very smooth, no edge at all (not necessary a good thing, but easy on the ears), and supprisingly bassy, though it doesn't go very deep.


----------



## fishpatrol

Thanks for the linky. I wonder how these amps would compare with the 252, which seems to be the other standard config. Dismaying upgrade dreams already, sorry about my wallet, etc.


----------



## EFN

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_Judging by the reloaction of the input jack, I supposed you are re-casing it? 

 if so, might as well add a regular 5-pin socket, they are not that big..._

 

Yep for this one a new case is needed since the C6 poly caps will be quite big. On top of that I am adapting a 24000 mAH PSP 5V battery with the new box


----------



## AudioCats

Quote:


  Originally Posted by *EFN* /img/forum/go_quote.gif 
_Yep for this one a new case is needed since the C6 poly caps will be quite big. On top of that I am adapting a 24000 mAH PSP *5V* battery with the new box 
	

	
	
		
		

		
		
	


	


_

 


 if you are using 8599, make sure there is enogh heat sink on the Q15 to get rid of the heat. It will get very hot with a 5V input.


----------



## borisov57

My left earphone just lost connection to one of the stators. Does anybody know, where to get replacement cable?


----------



## luvdunhill

Quote:


  Originally Posted by *borisov57* /img/forum/go_quote.gif 
_My left earphone just lost connection to one of the stators. Does anybody know, where to get replacement cable?_

 

I'd be interested in this info as well (or your broken cable) as I'd like to make an adapter out of a cable.


----------



## AudioCats

I installed a set of OPA627's, and it is working. So the reason why AD826's didn't work in previous experiment, was probably due to self oscilation as the 826's are much faster and prone to that. 

 The sound with OPA627 is smooth, but not better than the AD825 in any obvious way. At least for now. Still burning in.


----------



## borisov57

I have managed to repair broken cable. I have also glued small heatsink to Q15. Thanks AudioCats.
 Power consumption with OPA827 is 490mA. OPA627 consumes more, I guess. OPA627 is specified at 7mA, OPA827 4.8mA per amp. AudioCats, if you can, please try OPA827.
 I am listening to stax amp via low noise 3.7V regulator. It sounds cool.


----------



## EFN

The "doctor" is almost ready to operate.....90% of the caps ordered have arrived and in couple of days the Sonicaps .022 uF 600V, WIMA 0.1uF 630V MKP and 0.12uF 50V MKP will arrive which will make them all complete. I have custom Octave Audio .001 uF and Sonicaps 0.002uF to play with as well.


----------



## EFN

It's ALIVE!!!! *the doctor laughs gleefully*






 First impression, it's kinda darkish. BUT definitely larger sounding with strong visceral impact and slam. Bass and mids texture are quite audible. Taking into account that 70% of the caps are practically new, I'll let them burn in for a while and hopefully she will gain some sparkle and speed.

 Hidden beneath the caps are is a pair of AD8066AR. To accomodate those fatty caps, I have to sacrifice the battery compartment and now need to decide if I'd use an external piggyback battery or find a longer enclosure to integrate those all in one package......decisions, decisions.....

*EDIT:*
 Despite being slightly darker sounding, there's lots of details which I suspect a trait of the AD8066AR (I used the mono AD8065AR for my MiniBox-E+ which is highly detailed as well). Instruments separation and transients are quite articulate.....more to come


----------



## HeadphoneAddict

Quote:


  Originally Posted by *EFN* /img/forum/go_quote.gif 
_It's ALIVE!!!! *the doctor laughs gleefully*






 First impression, it's kinda darkish. BUT definitely larger sounding with strong visceral impact and slam. Bass and mids texture are quite audible. Taking into account that 70% of the caps are practically new, I'll let them burn in for a while and hopefully she will gain some sparkle and speed.

 Hidden beneath the caps are is a pair of AD8066AR. To accomodate those fatty caps, I have to sacrifice the battery compartment and now need to decide if I'd use an external piggyback battery or find a longer enclosure to integrate those all in one package......decisions, decisions.....

*EDIT:*
 Despite being slightly darker sounding, there's lots of details which I suspect a trait of the AD8066AR (I used the mono AD8065AR for my MiniBox-E+ which is highly detailed as well). Instruments separation and transients are quite articulate.....more to come_

 

My battery bay is full of caps as well. The AD8066 normally wont be dark, but wide and spacious and detailed, so I bet it clears with burn-in. I needed about 500 hours for everything to come into place.

 I am using a small Audiocats made external battery pack with 6 x 3.7v Li 14500 cells in parallel. Since the SR-001 internally limits voltage to 2.7v and there is double the current drain with my AD8599 opamps this results in a bit of heat in Q15 (whatever that is). 

 In my pack the batteries are protected from over discharge or over charge. I can charge the pack with a wallwart and run the SR-001 from the pack at the same time, or run my SR-001 with a wallwart and no pack. Unfortunately the charging plugs or inputs in the pack and SR-001 are different sizes, probably due to the limited choice of power supplies and pigtail power cable (to link the pack and SR-001) that Audiocats had on hand. Otherwise I could use the same charger for powering the SR-001 or charging the pack. Time to make an adapter.


----------



## EFN

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_My battery bay is full of caps as well. The AD8066 normally wont be dark, but wide and spacious and detailed, so I bet it clears with burn-in. I needed about 500 hours for everything to come into place.

 I am using a small Audiocats made external battery pack with 6 x 3.7v Li 14500 cells in parallel. Since the SR-001 internally limits voltage to 2.7v and there is double the current drain with my AD8599 opamps this results in a bit of heat in Q15 (whatever that is). 

 In my pack the batteries are protected from over discharge or over charge. I can charge the pack with a wallwart and run the SR-001 from the pack at the same time, or run my SR-001 with a wallwart and no pack. Unfortunately the charging plugs or inputs in the pack and SR-001 are different sizes, probably due to the limited choice of power supplies and pigtail power cable (to link the pack and SR-001) that Audiocats had on hand. Otherwise I could use the same charger for powering the SR-001 or charging the pack. Time to make an adapter._

 

So how long did they last on a single charge? And how do you charge them? using Ultrafire individual chargers or you have some sort of Audiocats modded charging capabilities integrated to the battery pack?

 Cheers.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *EFN* /img/forum/go_quote.gif 
_So how long did they last on a single charge? And how do you charge them? using Ultrafire individual chargers or you have some sort of Audiocats modded charging capabilities integrated to the battery pack?

 Cheers._

 

I haven't used it long enough to run down the batteries, I'll listen maybe 5-6 hours in a day and plug it in to charge - Audicats put an internal charging circuit inside the battery pack. So, I don't use my Ultrafire charger anymore, I use a Motorola wallwart or something that he included (but not a Moto mini USB).


----------



## EFN

After 12 hours runtime, true indeed the sound brightens a bit and not as dark sounding as before. But also I found out that I have accidentally severed a patch link between one the .001 uF caps with the resistor - re-attaching the link does make them sound like what they are supposed to sound.

 More hours to go but I am liking it very much already.


----------



## borisov57

Nice looking amp you have EFN. Output caps matching switching transformer in colour.
 I bet is sounds good.


----------



## EFN

Quote:


  Originally Posted by *borisov57* /img/forum/go_quote.gif 
_Nice looking amp you have EFN. Output caps matching switching transformer in colour.
 I bet is sounds good._

 

LOL now that you mentioned it I realized the amp internals looked very colorful now....

 Yes they do sound fantastic already. The punches have mellowed down a bit but the micro nuances are beginning to be a bit more prominent. Transients are very well handled too...all this with around 30 hours runtime. I have big hope for this amp now when it reaches over 200 hours.


----------



## marcus1

Hi EFN

 Great work, I'm thinking of doing something similar myself but funds are limited - do you mind if I ask how much the upgrade cost you (caps, opamps etc)?

 Thanks

 Tim


  Quote:


  Originally Posted by *EFN* /img/forum/go_quote.gif 
_After 12 hours runtime, true indeed the sound brightens a bit and not as dark sounding as before. But also I found out that I have accidentally severed a patch link between one the .001 uF caps with the resistor - re-attaching the link does make them sound like what they are supposed to sound.

 More hours to go but I am liking it very much already._


----------



## EFN

Quote:


  Originally Posted by *marcus1* /img/forum/go_quote.gif 
_Hi EFN

 Great work, I'm thinking of doing something similar myself but funds are limited - do you mind if I ask how much the upgrade cost you (caps, opamps etc)?

 Thanks

 Tim_

 


 Thanks. The parts all came from different sources and it is difficult for me to gauge actual cost. But I believe the caps. opamps and a few other parts would total up around $80-140 with some of the costs are due to international shipping charges. And it takes time to compile them all together. but you can cut down the cost if you can source a local supplier.


----------



## EFN

Finally completed. One of a kind SRM-001.












 * The three 5V cells boast 30,000 mAH of Li-Ion power and have extended the play time for over 13 Hours continously (Non-Stop). In contrast a pair of Ultrafire 3.6V will barely run for two hours. The batteries are rechargeable via an external charger box that I have made (not in the pics)





 Ready to ROCK!!!

 Still burning in. I am loving the sound already....

 PS: More pics at the Portable Audio section


----------



## HeadphoneAddict

Quote:


  Originally Posted by *EFN* /img/forum/go_quote.gif 
_Finally completed. One of a kind SRM-001.

 * The three 5V cells boast 30,000 mAH of Li-Ion power and have extended the play time for over 13 Hours continously (Non-Stop). In contrast a pair of Ultrafire 3.6V will barely run for two hours. The batteries are rechargeable via an external charger box that I have made (not in the pics)





 Ready to ROCK!!!

 Still burning in. I am loving the sound already....

 PS: More pics at the Portable Audio section_

 

That's wacky man!


----------



## webbie64

VERY impressive work, EFN. Good to see the gist of this thread continues to develop further versions of this little amp.

 Will look forward to comparisons with other versions.

 Maybe it's the pic but I'd be concerned the headphone connector sticks out from the case too much - risk of damage?

 Also, how is it for dispersing any heat it generates?


----------



## EFN

*webbie64:*
 Hey thanks mate. When one becomes too picky about this and that, the only solution is to DIY everything LOL!.

 At this stage, I have to admit this baby still have some more milage to go as the "well cooked" stock SRM-001 that I obtained from HeadPhoneAddict (which have over 500 hours) sounds so good that I almost questioned the need to mod them. But she's showing promises already and today I will pick up my Sonicap to replace the Octave Audio Polys which IMO is a bit too soft for my application.

 Yes, the headphone jack potruded a bit more but so far it is okay because once the jack is plugged in they are well protected.

*HeadphoneAddict:*
 Yah I know. Whacky! so much juice required just to power them up LOL


*EDIT:*
 Ah yes. Heat dissipation works better with this Hammond enclosure since they are made of Aluminium. The stock STAX box was plastic. After a while the whole amp body will get pleasantly warm and does not bother me much


----------



## HeadphoneAddict

Quote:


  Originally Posted by *EFN* /img/forum/go_quote.gif 
_*webbie64:*
 Hey thanks mate. When one becomes too picky about this and that, the only solution is to DIY everything LOL!.

 At this stage, I have to admit this baby still have some more milage to go as the "well cooked" stock SRM-001 that I obtained from HeadPhoneAddict (which have over 500 hours) sounds so good that I almost questioned the need to mod them. But she's showing promises already and today I will pick up my Sonicap to replace the Octave Audio Polys which IMO is a bit too soft for my application.

 Yes, the headphone jack potruded a bit more but so far it is okay because once the jack is plugged in they are well protected.

*HeadphoneAddict:*
 Yah I know. Whacky! so much juice required just to power them up LOL


*EDIT:*
 Ah yes. Heat dissipation works better with this Hammond enclosure since they are made of Aluminium. The stock STAX box was plastic. After a while the whole amp body will get pleasantly warm and does not bother me much_

 

Yeah, it was funny how a little burn-in could make a stock SR-001 sound so good - I wasn't sure I even liked it the first 350 hours. Now it has about 800 hours on it.


----------



## marcus1

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Yeah, it was funny how a little burn-in could make a stock SR-001 sound so good - I wasn't sure I even liked it the first 350 hours. Now it has about 800 hours on it._

 

Just wondered what model your stock SR-001 is - does it have the NJM062L or the Toshiba 062 opamp? Mine has the NJM which according to Audiocats is inferior to the Toshiba (see below, post # 63, 02/19/08)
 I'm wondering if its worthwhile trying an extended burn-in with my SR-001 (with the NJM opamp) before making a decision to tweak - is the NJM not good enough to get the improvement in SQ you have reported with your 800+ hour burn-in? 

 Thanks

 ************************************************** *************************************************
 [/QUOTE]Post # 63, 02/19/08
 AudioCats 

_Just found out that not all SRM-001's are made the same. Mine came with NJM062L, and the one Larry just sent me has the Toshiba made 062, which sounds quite a bit better than the NJM, almost as good as a TL082 upgrade. 
 If you have Toshiba chips in your 001, you might not want to change the opamp, just upgrading the input/output caps should give satisfactory performence, and you still have the same battery life as the stock amp._.[/QUOTE]


----------



## HeadphoneAddict

Quote:


  Originally Posted by *marcus1* /img/forum/go_quote.gif 
_Just wondered what model your stock SR-001 is - does it have the NJM062L or the Toshiba 062 opamp? Mine has the NJM which according to Audiocats is inferior to the Toshiba (see below, post # 63, 02/19/08)
 I'm wondering if its worthwhile trying an extended burn-in with my SR-001 (with the NJM opamp) before making a decision to tweak - is the NJM not good enough to get the improvement in SQ you have reported with your 800+ hour burn-in? 

 Thanks


  Quote:


 Post # 63, 02/19/08
 AudioCats 

Just found out that not all SRM-001's are made the same. Mine came with NJM062L, and the one Larry just sent me has the Toshiba made 062, which sounds quite a bit better than the NJM, almost as good as a TL082 upgrade. 
 If you have Toshiba chips in your 001, you might not want to change the opamp, just upgrading the input/output caps should give satisfactory performence, and you still have the same battery life as the stock amp.. 
 

_

 

The SR-001 that audiocats is talking about in the quote above is the very same one I sold to EFN - we both decided it sounded too good to modify while it was under warranty. So I left it stock and bought another one to mod. Then I was going to mod the good one with better caps later when the warranty ran out in January, but EFN PM'd me about buying it before I could do mods.

 So, if you have the NJM in yours then you need a new opamp, if you have the 062 like the one I sold EFN you might be happy with just upgrading all the caps and having good internal battery life.


----------



## EFN

Yep. That was one of the primary reason I purchased the un-modded Toshiba opamp model from HeadphoneAddict, that thing is already good sounding compared to the older opamps (the one I purchased from Quaddy) and became the benchmark reference for me to mod. I have to tweak a lot on my older SRM-001 just to match the output of the Toshibas.

 So if you have an SRM-001 with Toshiba opamps, consider yourself VERY lucky because after 500 hours they sound blissfull enough and probably need minor mods.

 Now that I am almost done tweaking my first unit, the Toshiba SRM-001 unit has been spoken for and will be sold to another eager Head-Fier. I only have two ears for four earspeakers LOL!


----------



## HeadphoneAddict

Quote:


  Originally Posted by *EFN* /img/forum/go_quote.gif 
_Yep. That was one of the primary reason I purchased the un-modded Toshiba opamp model from HeadphoneAddict, that thing is already good sounding compared to the older opamps (the one I purchased from Quaddy) and became the benchmark reference for me to mod. I have to tweak a lot on my older SRM-001 just to match the output of the Toshibas.

 So if you have an SRM-001 with Toshiba opamps, consider yourself VERY lucky because after 500 hours they sound blissfull enough and probably need minor mods.

 Now that I am almost done tweaking my first unit, the Toshiba SRM-001 unit has been spoken for and will be sold to another eager Head-Fier. I only have two ears for four earspeakers LOL!_

 

Will you mod it first with better caps, then sell? Makes more sense...


----------



## EFN

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Will you mod it first with better caps, then sell? Makes more sense..._

 

Yep there will be minor mods because I don't want to end up screwing up what's already a good sounding system


----------



## HeadphoneAddict

Quote:


  Originally Posted by *EFN* /img/forum/go_quote.gif 
_Yep there will be minor mods because I don't want to end up screwing up what's already a good sounding system 
	

	
	
		
		

		
		
	


	


_

 

Or, you could keep it since you went through all the trouble to get it shipped halfway across the world.


----------



## EFN

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Or, you could keep it since you went through all the trouble to get it shipped halfway across the world._

 

LOL, I am selling it to a local Head-Fier who has been yearning to own a STAX system for a very long time. I am doing him a favor actually and it's just seems right to "share" the goodness of portable electrostatics. I am very confident he will cherish them a lot


----------



## EFN

Burn In Update:

 Today was a good day. 48 hours has passed and the modded SRM-001 is beginning to sound just like what I intended it to be - generally warm throughout the entire spectrum and very lush on the highs with no overbearing emphasis on treble. For some reason the sound is VERY wide and well textured. Compared to my ER-4 and K701, they can be considered as dark sounding - but not the Senn type of darkness because the speed and resolution is all over the place.

 Compared to the unmodded Toshiba SRM-001, my modded unit still sounds a bit darker and this is perfect for my use. I'd figured within the 200 hours range the modded SRM-001 will definitely sing a lot better still.

 The most important part is that there's no fatigue no matter how long I plugged them on - this is something I can't do with the ER-4S which will induce fatigue after 3 hours of use.


----------



## borisov57

Hello! Nice to hear, that you are liking yours SRM-001, EFN. I would also say, that mine is as dark as sennheiser, but somehow more direct and fast, so it is fun to listen. 
 My guess is, that stock toshiba unit is brighter because of distortion produced by stock input electrolytic.


----------



## marcus1

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_The SR-001 that audiocats is talking about in the quote above is the very same one I sold to EFN - we both decided it sounded too good to modify while it was under warranty. So I left it stock and bought another one to mod. Then I was going to mod the good one with better caps later when the warranty ran out in January, but EFN PM'd me about buying it before I could do mods.

 So, if you have the NJM in yours then you need a new opamp, if you have the 062 like the one I sold EFN you might be happy with just upgrading all the caps and having good internal battery life._

 

Providing they can be used, I already have a couple of LT1361CN8 opamps - is it worth giving these a go in place of my NJM062L's? 

Linear Technology - LT1361 - Dual and Quad 50MHz, 800V/µs Op Amps LT1361 LT1361CN8#PBF LT1361CS8#TR LT1361CS8#PBF LT1361CN8 LT1361CS8 LT1361CS8#TRPBF

 Thanks


----------



## EFN

Quote:


  Originally Posted by *marcus1* /img/forum/go_quote.gif 
_Providing they can be used, I already have a couple of LT1361CN8 opamps - is it worth giving these a go in place of my NJM062L's? 

Linear Technology - LT1361 - Dual and Quad 50MHz, 800V/µs Op Amps LT1361 LT1361CN8#PBF LT1361CS8#TR LT1361CS8#PBF LT1361CN8 LT1361CS8 LT1361CS8#TRPBF

 Thanks_

 


 That is something you have to try. I have no experience with LTs. That's the fun of DIY


----------



## moray james

a buddy of mine just got an SRM001 and would like to run it from a wall wart supply. Can anyone here please provide information so he can order a male plug for the odd ball female power socket on the back of the unit? The local parts supplier does not have one that fits so some details would help. Thanks.


----------



## EFN

Quote:


  Originally Posted by *moray james* /img/forum/go_quote.gif 
_a buddy of mine just got an SRM001 and would like to run it from a wall wart supply. Can anyone here please provide information so he can order a male plug for the odd ball female power socket on the back of the unit? The local parts supplier does not have one that fits so some details would help. Thanks._

 

The SRM-001 uses standard yellow tipped plug which is quite common for PCDPs and most portable devices. I recommend that you look for the Sony PSP Wallwart because it will work just fine with the SRM-001


----------



## EFN

Burn In Progress Update:

 By now, my modded SRM-001 have probably clocked some 120 hours. The bunch of caps would have settled down more and the sound becoming more balanced with each passing day. As of now, I can audibly hear high frequency sparkle which was somewhat distant sounding during the 20-70 hours period. But I reckon even now the brightness is still not as pronounced as my modded ER-4S and the stock Torshiba SRM-001 - which is nice because I am not looking to have a treble focused system. It's a depature of taste for me, I am no longer an addict to the sparkly sound of ER-4S which is quite sharp sounding. The modded SRM-001 opened my eyes to the meaning of "balanced" and "neutral"

 OTOH, I am "cooking" two sets of boutique caps, the Sonicap 0.022uF and Mundorf Silver/Oil 0.022uF. Those are for the output stages. Currently I am happy with the Octave 0.01uF caps, the Sonicap and Mundorf are options for me to roll and experiment on sound attributes and I will keep the ones which suit me the best


----------



## EFN

A 2nd project like the first one. This is for another Head-Fier.

 With much difficulties I have managed to squeeze them into a smaller case.

 Now with:
 - 26,000 mAH Battery
 - Built in recharging circuit
 - Different sets of Elna SILMIC caps


























 Oh they do sound blissful


----------



## HeadphoneAddict

Quote:


  Originally Posted by *EFN* /img/forum/go_quote.gif 
_A 2nd project like the first one. This is for another Head-Fier.

 With much difficulties I have managed to squeeze them into a smaller case.

 Now with:
 - 26,000 mAH Battery
 - Built in recharging circuit
 - Different sets of Elna SILMIC caps

 ...SNIP...






 Oh they do sound blissful_

 

NICE! Looks like I should try to get mine re-cased like that, instead of having a separate battery pack piggybacked with my SR-001. Hmm...


----------



## EFN

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_NICE! Looks like I should try to get mine re-cased like that, instead of having a separate battery pack piggybacked with my SR-001. Hmm..._

 

Thanks but they are super tight. To close the box I have to apply force for the first time.


----------



## Questa

envy.....


----------



## ak40ozKevin

So my SR-001 has the NJM opamps and is completely stock. Is there a fairly straightforward way to simply upgrade the opamps and leave everything else stock and still yield some kind of improvement? I don't really want to lose any battery life which is another thing keeping me from modding. Are the superior Toshiba opamps available to purchase anywhere?

 Sorry if this is posted elsewhere in the thread.


----------



## borisov57

Hello ak40ozKevin,

 Google says:
TA75062 Diodes Diode Arrays Independent Multidiodes Datasheet pdf specifications specs Discrete Semiconductor sale at AMS Inc.

 You could also consider replacing input electrolytics with Black Gates.

 Good luck


----------



## fishpatrol

Has anyone taken the plunge and tried to get molded earphones to fit their SRM-001? My poor earlobes are taking a beating. What substance could I use as a test case? Silly Putty? Sticky tack? Some kind of wax?


----------



## 66645

Quote:


  Originally Posted by *fishpatrol* /img/forum/go_quote.gif 
_Has anyone taken the plunge and tried to get molded earphones to fit their SRM-001? My poor earlobes are taking a beating. What substance could I use as a test case? Silly Putty? Sticky tack? Some kind of wax?_

 

It would be interesting for me as well.


----------



## ericj

Hey, question for people who have messed around with lithium packs more than i have. 

 I bought an sr-001 mk2 kit that will be arriving next week. I plan on doing some modifications, including the parallel 3.6v batteries. 

 I'm aware that the protected 14500 cells don't fit, and I've seen where some have taken one of the protection circuits and just mounted it inside the case. 

 I've been repairing a lot of DAPs over the last several months and i haven't gone looking for a place to legally recycle lithium packs - I have about a dozen old DAP packs in various states ranging from expanded to dead to just fine but too low capacity by design. 

 Could i get away with pulling the protection circuit off of one of those packs and mounting it inside my srm-001?


----------



## luvdunhill

Quote:


  Originally Posted by *ericj* /img/forum/go_quote.gif 
_I'm aware that the protected 14500 cells don't fit_

 

They do in fact fit. That's what I use, and there's a post someone here where someone else uses them. I think I posted pics in this thread somewhere.


----------



## ericj

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_They do in fact fit. That's what I use, and there's a post someone here where someone else uses them. I think I posted pics in this thread somewhere._

 

I saw posts both for and against. 

 At any rate i already ordered the unprotected cells, and i can lay hands on a dozen or so protection circuits from li-po packs just around my own workbench. 

 They all seem to have the same stuff on them.


----------



## luvdunhill

Quote:


  Originally Posted by *ericj* /img/forum/go_quote.gif 
_I saw posts both for and against. 

 At any rate i already ordered the unprotected cells, and i can lay hands on a dozen or so protection circuits from li-po packs just around my own workbench. 

 They all seem to have the same stuff on them._

 

If you're not using the DC input on the amp to charge the cells and if you do proper modifications to the shut off circuit, I'm not sure how necessary they are. If you modify the DC input to charge the new cells, be careful as you can cause the regulators to run real hot.


----------



## marcus1

I want to replace the NJM opamp for the superior Toshiba TA75062 opamp but the only business that sells them (that I can find) is the one mentioned by borisov57 below.
 Problem is that American Microsemiconductor has a minimum $50 purchase and they charge a whopping $165 to ship overseas that makes the 0.39 cent opamp quite expensive! 
 Anyone know of any other place that sells them or perhaps someone has a couple spare they can sell to me?
	

	
	
		
		

		
			





 cheers

 Tim

  Quote:


  Originally Posted by *borisov57* /img/forum/go_quote.gif 
_Hello ak40ozKevin,

 Google says:
TA75062 Diodes Diode Arrays Independent Multidiodes Datasheet pdf specifications specs Discrete Semiconductor sale at AMS Inc.

 You could also consider replacing input electrolytics with Black Gates.

 Good luck_


----------



## Astertyhity

John B. aus Edmonton feierte am 27. September 2008 durch die Benutzung von Garrett Metalldetektoren den Fund seiner 100.000sten Münze. "Das hat fast 15 Jahre gedauert", sagt er. "Der Gesamtwert wurde auf etwa 3600 $ geschätzt."


 ace 250 ace 250 metallsuchgerät


----------



## Dinan

Another SFC+ modded 001 Mk2 has been built! After having the parts sit around for weeks, I finally found the time to do the mod over the last couple of mornings. I didn't get more than 10 minutes to listen to the finish product as I was just doing a quick test but the first things that struck me were how deep the bass goes (really low) and the wonderfully liquid midrange and top end. 

 I look forward to burning it in for another 200 hours with the mods for a total of 500 hours and doing a real listen. But at the moment, it is a perfect compliment to my O2 rig to take traveling. 

 After much debate, I left it in the stock case as I like the compactness. I am thinking that I will paint the case top and battery case (I have yet to build this) in Ferrari Red or some other eye catching automotive finish as I have to have some bling to go with the zing! 

 I strongly recommend this mod as it is well worth the expense of a new SR-001 rig and the cost of parts.


----------



## Dinan

I did a little research on Q15 with two different power adaptors measuring voltage and the temperature using a very expensive probe pyrometer. 

 Sony 4.5V 500mA #AC-E5455:

 4.72V loaded
 Q15 at 129* F

 STAX 4.5V 300mA #SR-AC001

 4.27V loaded
 Q15 at 113* F

 The STAX wall wart is rated below the current draw of the SFC+ modded unit which explains why the voltage is on the low side at only 4.27V but out of the 2 units above, it sounds the best and gives up nothing in the bass. 

 One thing to keep in mind is the the current rating is typically for the specified voltage. So a 4.5V 300mA unit will output the rated voltage around 300mA of draw or load. So if you pull more current, the voltage drops, less and it will rise. 

 Anyway, just thought I would share.


----------



## AudioCats

I assume the temp measurement is taken from the case surface, right? 113F seem a bit low if it was directly from the Q15 itself.


----------



## GuyDebord

Hi all... Im looking for someone willing to perform the super fat cat mod on my srm-001. 
	

	
	
		
		

		
		
	


	




 Im absolutely not skilled to perform any form of surgery... Im sure we can arrange.... please pm me if you want to make a headfier very happy....


----------



## randytsuch

Hi guys

 My SRM 001’s have been gathering dust lately, but I just resurrected them, and remembered how good they can sound.

 I did a few mods a while ago, I put BG input caps, 47uf NX’s.
 I installed BG N caps in C3, C27 and C28, also in the ones next to the input caps, forget the numbers right now.

 I have been planning to make a major mod, based on the UFC

 I am going to recase to a larger case, whatever size I need to fit everything.

 New battery
Rechargeable Batteries & Battery Chargers - Li-Ion 18650 3.7V 5200 mAh Rechargeable Battery PCB module with Bare Leads

 More power then I need, but the price is right

 Battery charger
charger
 I was thinking about making a simple charger, then started looking at Maxim Li charger chips, and then started to think why not just buy one. This one charges at both 1A and 0.5 A, the one from all battery just charges at 0.5A, so it will be slower. Since I am using a high capacity battery, a 1A charge rate is fine, that battery could take up to 2.6A charge rate no problem.

 Input caps
 Will probably just use the BG’s I already have installed for now, but planning to buy the 220uf BG NX’s. I was also thinking, if whatever you connect to has output coupling caps, you really don’t need input caps, they are redundant at that point.

 Output caps.
 Planning to try
 Audiocap Theta
 Relcap RT
 Relcap RTX

 Opamp
 Planning to try
 LMH6642MA
 AD825
 AD8599
 Going to use Browndog adapters, to make it easier to install.

 Other fat cat mods, 
 Replace C17, C18. and C6.
 Add four fast electrolytics directly from the opamps’ VCC/Vdd pins to the ground. 
 Short out R33/34/35. 
 Add a good electrolytic cap between ground and DC input + (after the switch).

 Pot
 I am thinking, since I am going to recase, to use a Blue Velvet pot. I haven’t measured the existing pot yet, to see what value I need. This will also mean that I will have to add a separate on/off switch.

 Hardwiring
 I was thinking about using a different connector, but then saw some posts about hardwiring, and decided that would be better, so current plan is to hardware the phones to the new chassis. I will install the output caps and 15 meg resistor off of the PWB, next to the hole for the headphone wires.

 Other caps
 There are some other lytic caps that can be replaced
 C13,14,15,16, 2.2uf, 350V
 C11, C12 6V, 22uf Surface Mount
 C25, 16V, 10uf Surface Mount

 I am going to order some Panasonic FC’s to replace the existing surface mount caps.

 C13-16 are a little harder, because they are such high voltage. All the pannys I have found so far are too large, am still looking for options here.

 Randy


----------



## randytsuch

BTW, my SR001 had Toshiba opamps, but I am planning to change the opamps out, so I might consider trading it for another one.

 It is partially modded, blackgates on the inputs and some other places, so it can't be a "straight" trade, wouldn't make sense for me.

 PM me

 Randy


----------



## Sim1

Quote:


  Originally Posted by *AudioCats* /img/forum/go_quote.gif 
_the plug: *< -a-b-c-d-e-f- ]*

 a: not connected, serves as a switch so the amp will turn off when the cable is unplugged.

 b: right side outter stator

 c: right side inner stator (toward your ear)

 d: left side inner stator (toward your ear)

 e: bias

 f: left outter stator
_

 

I guess I found a source for plug replacement. It is 7 pin SATA plug, it requires some work but for sure it fits the "socket".






 (1 Ground)-(2 Transmit +)-(3 Transmit -)-(4 Ground)-(5 Receive -)-(6 Receive +)-(7 Ground)

 If you remove (cut or whatever the extending piece of plastic from pin1 side and work a little on the other end of plug you will be able to plug it to energizer without any problems and fit *1-f 2-e 3-d 4-gap 5-c 6-b 7-a*.

 The only problem is at the moment that pins 1,4 and 7 seems to be shorted directly in a plug but since connetion "a" can be ignored and pin4 corresponds to the gap in energizer, the only issue is how to remove or isolate pin 7 in the plug... then everything else could fit and work. But obviously it would require to short a connection in energizer permanently.

 I checked the connections pin by pin plugging such sata cable to the open energizer pcb so I am sure it fits. The only thing I am not certain is if sata wires are good to transmit signals from energizer... that is something I have to check. But I wanted to share this discovery not waiting for the experiment to complete 
	

	
	
		
		

		
		
	


	




.

 If it works I'll be easy to make an adapter for standard 5-pin pro bias even without opening the adapter 
	

	
	
		
		

		
		
	


	




.


----------



## fidele-caput

Hi folks, first, my special thanks goes to AudioCats for his amazing exploits. Thoroughly enjoyed.

 I've got a Kensington Batterypack Battery Pack and Charger for iPhone and iPod - K33396US - Kensington I wanna make a smaller power cable (and efficient if possible) to drop the USB 5V to what? 3.5V? Ideas are welcome and thanks in advance!

 UPDATE: I've made the USB power cable, feeding 3.6V to the amp, but it won't turn on without the AA, do I need two dummy AA to make it work?


----------



## randytsuch

You don't need AA batteries installed, if you are feeding it power through the external jack, I do it all the time.

 The headphones are plugged in, right? I've forgotten to do that more then once.

 Randy


----------



## fidele-caput

Strange. Mine won't turn on if there is no battery. It could, only if I short the battery poles.

 The phones are plugged at all time. BTW, I've got a newish model here.


----------



## randytsuch

Quote:


  Originally Posted by *fidele-caput* /img/forum/go_quote.gif 
_Strange. Mine won't turn on if there is no battery. It could, only if I short the battery poles.

 The phones are plugged at all time. BTW, I've got a newish model here._

 

That is strange, I haven't had batteries in mine for a while, just running off an AC adapter.

 I am recasing mine into a larger box, to accomodate the changes I am making. Just removed the existing power input jack, and converted to a chassis mount one. I also added a switch to turn off power. I lost the power switch because I removed the existing volume pot, and replaced it.

 Reason I bring this up is that I looked a little at the power in when I did this, and I think the battery and the external power in go to the same place, at least in my version, which is an older one. I bought it used a few years ago. So, as far as I can tell, the SRM can't tell if it is running from batteries or external power, it just knows that power is coming in from somewhere.

 BTW, what do you mean when you say you're shorting the battery poles?

 Randy


----------



## fidele-caput

Quote:


  Originally Posted by *randytsuch* /img/forum/go_quote.gif 
_Reason I bring this up is that I looked a little at the power in when I did this, and I think the battery and the external power in go to the same place,_

 

You're right. I was wrong. I got it mixed up with my crappy power cable. lowered the usb 5V (resistors divider) to 4.6V and it's not working. I'll just suck it up and use 14500. Thanks mate.

 edit. ps: I made two dummy AA batteries to short the poles.


----------



## jung

Is there any NiMH 1/2 AA? If 4 half AA can fit into the 2 AA slots, it would double the voltage to 4.8V for better sound, but maybe cut the play time to half.


----------



## Questa

Hey guys, if I want to use full size phones for ultra fat can srm001, what is you guys suggest? 
 maybe some of you will say like its not powerful enough, I know that, but what if we don't have other stats amp beside FCU srm001, what stat the phones that the easiest to handle?


----------



## krmathis

^ Something relative small (diaphragm wise) as the SR-X/MK3 Pro maybe? Just guessing, as I have no idea about the power capabilities of the SRM-001.


----------



## Questa

yeah I'm thinking of that also, but they are as rare as a unicorn


----------



## AudioCats

You can also try the wide-ribbon Lambda's. The sound will be a little soft but might not be a bad thing.


----------



## borisov57

Hi AudioCats and all,

 I have put OPA1642 in my SRM-001, primary reason was lower consumption than OPA827.
 But, oh boy. This is op-amp is made for SRM-001.
 It's very low noise and distortion, low input current and high gain translates in sound, which is so good, that........ I am not to good in describing sound, but what I am listening right now is simply breathtaking ( high frequencies too ).

 A lot of fun to everyone,

 borisov57


----------



## marcus1

Hi Boris

 Does the OPA1642 directly replace the stock opamp or do you have to modify it to fit into the existing socket? 

 Thanks

  Quote:


  Originally Posted by *borisov57* /img/forum/go_quote.gif 
_Hi AudioCats and all,

 I have put OPA1642 in my SRM-001, primary reason was lower consumption than OPA827.
 But, oh boy. This is op-amp is made for SRM-001.
 It's very low noise and distortion, low input current and high gain translates in sound, which is so good, that........ I am not to good in describing sound, but what I am listening right now is simply breathtaking ( high frequencies too ).

 A lot of fun to everyone,

 borisov57_


----------



## borisov57

Quote:


  Originally Posted by *marcus1* /img/forum/go_quote.gif 
_Hi Boris

 Does the OPA1642 directly replace the stock opamp or do you have to modify it to fit into the existing socket? 

 Thanks_

 

In SRM-001 there are pads for dual SMD op-amps like OPA1642. But resistors in power supply filters must be changed also, because of higher supply current (1.8 mA vs. 0.5 mA of stock Toshiba op-amps).


----------



## marcus1

Thanks Boris - just checking; is this the correct part below?
OPA1642AID Texas Instruments Op Amps


  Quote:


  Originally Posted by *borisov57* /img/forum/go_quote.gif 
_In SRM-001 there are pads for dual SMD op-amps like OPA1642. But resistors in power supply filters must be changed also, because of higher supply current (1.8 mA vs. 0.5 mA of stock Toshiba op-amps)._


----------



## borisov57

Yes marcus1, that is the one, I am using.


----------



## marcus1

Thanks Boris; last question :*)

 In post #94 you described your modification:

_"Hello,

 Here is picture of changed input and output caps. Input is BG 47u/6V3 NX and output caps are Wima polypropylen 47n/630V. Power supply cap is Epcos X2 100n.
 After this photo was taken, I changed four power supply caps (10u/25V) with 100u/25V Rubycon ZLG and bypassed BGs with 68p silver mica."_

 Does the above (along with the new OPA1642 and resistors in power supply filters) accurately describe your current set-up?

 Thanks again


----------



## borisov57

Quote:


  Originally Posted by *marcus1* /img/forum/go_quote.gif 
_Thanks Boris; last question :*)

 Does the above (along with the new OPA1642 and resistors in power supply filters) accurately describe your current set-up?

 Thanks again_

 

Yes, that is about everything. There are also some small lytics around op-amp-s, which I changed for polypropylen. Black gate-s should be as good and probably better. But this is minor thing.
 I did not try any other high voltage supply and output caps, you should refer to Audiocats to find out, which are best.
 Supply resistors are 100 ohm and 22 ohm to compensate for higher supply current of OPA against Toshiba amps. If you plan to try AD8599, they should be even lower or no resistors at all.
 Power supply in my case is SiC diode rectifier, RCLC filter ( 2 x 33000uF ) and then low noise discrete 3.6 V regulator. Regulator is not my design, so I can not go in details about it.

 Best regards and have a lot of fun,
 borisov57


----------



## gsawdy

Hi All 001moders,
   
  I bought an UFC+ modded unit from Questa and I just want to thank Audiocats and the others who contributed to the evolution. 
   
  This is amazing.  I have the JH13pro which are wonderful in their own right but right now I find myself choosing the 001UFC+. 
   
  Perhaps its the novelity of it but I do want to say a big THANKS to Audiocats,
   
  George
   
  PS--Will we owners watch as the value if these climb since Stax is no longer making them?   VBG


----------



## AudioCats

I thought Stax was planning to release a new portable system soon. Maybe that is why they discontinued the 001mK2?


----------



## gsawdy

Humm,  I don't have any inside info.  They still are making the phones so it could be a new amp only--not too big a project.   Given how HP have surged in the market, it makes sense that they wouldn't abandon this growing market to JHAudio.  Market share is very important in Japaneese business thinking--but Stax may be the exception.
   
  BTW can you link me to a thread where options for earpads are discussed?   So far I've found the Stax rings work best--they are the only things that present the full frequency response.  Everything else, while more comfortable, sounds better when they are pushed/held in or when I open my mouth/make a face.
   
  George


----------



## HeadphoneAddict

Quote: 





audiocats said:


> I thought Stax was planning to release a new portable system soon. Maybe that is why they discontinued the 001mK2?


 

 I took my SR-001 (which you modded a while ago) to Westone on Wednesday, and Doug and Karl both thought it sounded very good with the HiFiMan HM-801 and 24/96 FLAC.  It would be a shame if Stax doesn't keep producing something similar.


----------



## AudioCats

How do you use the HiFiMan as signal source, Larry? does it have a line-out or simply use the headphone out?  How does it compare (as a source) to an iMod with a V-cap dock?


----------



## HeadphoneAddict

Quote: 





audiocats said:


> How do you use the HiFiMan as signal source, Larry? does it have a line-out or simply use the headphone out?  How does it compare (as a source) to an iMod with a V-cap dock?


 
   

The 801 has a line out and a headphone out.  I prefer it to my iMod/Vcaps by a small but appreciable margin, mostly with hi-res 24/96 files.  
   
  My main gripe is being limited to swapping 8-32 Gb SD cards in and out.  I can fit about 30-32 lossless 16/44 FLAC albums on an 8 Gb card, or 7-8 24/96 albums.  I have four 8 Gb SD cards to play with, and two of them are filled with 24/96 music.  The huge power brick is another issue I have with it.
   
  My HM-801 review:  http://www.head-fi.org/forum/thread/424091/hifiman-hm-801-portable-player-dac-review-part-one-of-two/600#post_6704606
   ​


----------



## AudioCats

interesting. Might be a good source for transportable electrostatic rigs.


----------



## gsawdy

Can someone tell me if I'm correct here, Please?
   
  I need to build a new LOD from my DIY iMod to the SRM-001.  I don't need any caps because the 001UFC has blocking caps on the input--Right or Wrong?
   
  TIA,   George


----------



## AudioCats

you will need the dc blocking caps, or the iMod's DAC won't work..


----------



## gsawdy

Quote: 





audiocats said:


> you will need the dc blocking caps, or the iMod's DAC won't work..


 

 Thank you AudioCats.  I was thinking that the SRM-001 amp had caps on the input.  Glad I found out otherwise!
  George


----------



## fscerbo

dear audiocats,
  i have a toshiba opamp stax-001 i would like to upgrade. i already bypassed input caps becouse my source has not dc signal.
  becouse in italy is difficult to find caps for c7 c8 c27 c28 c6 upgrade you suggest, i would ask you if you could sell me those caps. I will pay caps and shipping
  bset regards
  francesco


----------



## AudioCats

will the amp still work with the input caps by-passed? I have never tried that before...
   
  I don't have mod parts left. you can use any boutique capacitors as long as they fit.


----------



## Robot Metal

Is anybody willing to sell their modded SRM-001 or mod mine? Thanks in advance...


----------



## duanewhitney

Does anyone know if I need DC blocking caps for a line out from a Sansa Fuze feeding into a modified SR-001MKII?  The fuze lod diy thread shows two versions--one with and without 200uf caps.  I tried 220 uf Nichicon nonpolar electrolytics, but the sound quality suffers even after patching in a small film cap in parallel.
   
  btw, I talked with a Stax dealer earlier this year.  He said they would be coming out with a new driver unit at the end of the year, and that they would be using the same ear speaker as the current version.


----------



## vidsan

For creating an external battery pack to connect to the 4,5V plug -- how much can the voltage deviate? Will 4,8V be too much? 3,7V be too little? Are there other considerations I need to take into account? mAh? Should the mAh be as high as possible?
   
  How do I modify the battery bay to paralell?
   
  Another thing -- regarding the mods in this thread: Having only skimmed it, how much soldering must I have done and how much electronics knowledge do I need? Can I simply  follow the recipe and expect it to work?


----------



## Student_Driver

Quote: 





robot metal said:


> Is anybody willing to sell their modded SRM-001 or mod mine? Thanks in advance...


 


  I have the same question. Have the SRM-001 but don't use very much. Might like it better with the mod. Thanks.


----------



## ecodoppler

Hi AudioCats
 I read with great interest your threads on Stax SRM-001headphones and I wish
 to modify mine but there's a problem; I bought my Stax from Japan one years ago
 but soon I noted a great distortion on the right channel. So I decided to send
 the headphone to Japan  to repair it; after one month, I received
 the stax but, again, I noted the same distortion. I complained to the Japanese dealer
 about Stax Industry's behavior, but, obviuosly, I couldn't ship it again. Well,
 the question is: by modifying the headphone following your suggestion, could I
 solve the problem of the distortion and improve the sound as well?
 thank you
 Best Regards
 Ecodoppler


----------



## AudioCats

ecodoppler, if the problem is indeed in the amp, the mod might not solve your problem. These mods are just parts upgrades, your amps might have bad output FETs, which is not touched in the above mods.
   
  vidsan, if you are using a stock amp, anywhere between 3 and 6V will be ok. If you are using a modded amp the voltage should not be higher than 4.5V, or the Q15 can get hot really fast. Modding the battery bay to parallel is a major pain in the a, it is difficult to find room inside the case to add li-ion protection circuit board.
  Soldering skill-wise, you need to be able to solder surfact mount IC's.
   
  Is there a release date for the new amp yet?.


----------



## spritzer

Quote: 





audiocats said:


> Is there a release date for the new amp yet?.


 

 I haven't heard anything


----------



## ecodoppler

AudioCats
  thank you for your explanation. And If I change the output FETs? At this point I cannot to ship again to Japan and I could give a try to this amplifier. What you propose?
  Thank you
  Ecodoppler


----------



## pbandstefanwich

What do you guys think about using a USB port as a power source? I believe it provides 5V and 500mA, but you could also string together two USB ports in parallel to get up to 1A like they do with some portable hard drives. Please correct me if I'm wrong, but I would assume it would be a cleaner power supply than most wall warts because it's coming from the DC laptop battery?
  I think I am going to mod my Baby Stax and put it into a slightly larger case to allow room for some bigger batteries. How hard do you think it would be to work in a USB charging circuit so all you'd have to do to charge the batteries would be to plug your SRM into a USB port? If that won't provide enough power it might also be possible to work in a Firewire charging port, as I think that puts out 12V and up to 1.25A.


----------



## vidsan

@AudioCats: Thanks for the answer. I've bought normal rechargeable AA's, 2500 mA, and a pair gives me more than eight hours of continual use. Having an extra pair always at hand, running out of juice is no problem.
   
  A question on static: My right speaker sometimes gives off a sort of crackling noise but then disappears. I am holding my right ear as a suspect as it is slightly larger than my left ear. Are there other possibilities? Warm-up time etc.?
   
  Thirdly: I've shrink tubed the amp connector for more durability, but I'm still really worried I'll break the cable somehow. Is there a way to change the cables with something sturdier? Other DIY cable mods?


----------



## rlmoss

Google is increasingly useless, Search audiocats and it returns anything but your url. Search on audiocats.url and it returns youtube array. What is your url? One reviewer noted your mod of portable amp in former SR-001 better than one in SR-003 package. Big price bump from SR-001 to SR-003, quoted on Black Friday at $750
   
  thanks,
   
  Richard
   
  rlmoss@penguinmail.com


----------



## MrTom

Quote: 





pbandstefanwich said:


> Please correct me if I'm wrong, but I would assume it would be a cleaner power supply than most wall warts because it's coming from the DC laptop battery?


 


  Hello,
   
  I'm almost certain that the 5 V will not be wired directly from the battery as most laptop batteries are in the magnitude of 12-16 V. I'm guessing that it would be a DC-DC class D power supply due to the efficiency afforded and relatively low cost of implementation. If anyone knows any differently please say so as I'm interested!


----------



## pbandstefanwich

Quote: 





mrtom said:


> Quote:
> 
> 
> 
> ...


 

 I'm not completely familiar with the class D rating, but after a brief google search it seems that class D use PWM and a high switching frequency to lower down the voltage. Is that correct? If that's really what they use in most laptops, then it certainly doesn't sound like a clean power source for this application! Is there an easy way to measure this or to measure how stable the USB power supply would be? i.e. if I hooked up a simple voltmeter to my USB ports, would I be able to detect fluctuations small enough to actually make a significant impact on the audio quality?
   
  If most USB ports are actually PWM, then it probably wouldn't be suitable to run the amp directly off of the port, but it would be fine to use the USB to charge the batteries, correct? It would probably take longer than using a wall wart, but I think it would be a nice feature because of the convenience factor... instead of having to carry around a wall adapter when you travel you could just carry a simple USB cord that could also be used by many other devices you might have on you.


----------



## ecodoppler

AudiCats
  I changed output Fets and Transistors but unfortunately I didn't solve the problem; after three minutes I hear an annoying distortion on the right channel. Do you think the replacement of the output Opamp could solve the problem?
  Thank you
  Ecodoppler


----------



## AudioCats

If the amp is stock, I don't think the opamp can cause problem, they are running at moderate voltage there is no reason for them to distore.
   
  The only thing I can think of right now is to try another set of phones just to make sure the phones/cable are not the problem.


----------



## kiromn

Dear AudioCats,I have just made the FC class MOD and it sounds fantastic. The only issue is that i could not find the 0.1u 630V, so used only the stock output caps in paralel for this task. Can you recommend some replacement that can be found in stock? Conrad has WIMA caps, but there are several 0.1uf 630v available and i am not quite sure what is the difference.Thanks in advance and admirations for the hard work you have done, so all of us can do the mod.


----------



## Robot Metal

I have a broken SRM-001 here. The original owner apparently went over the volts it's supposed to take. Is it possible to fix it by replacing parts, and if so which ones? I'll dump money into mods, I just want to at least see it work first before any serious money gets put into it.


----------



## jung

Quote: 





ecodoppler said:


> I changed output Fets and Transistors but unfortunately I didn't solve the problem; after three minutes I hear an annoying distortion on the right channel. Do you think the replacement of the output Opamp could solve the problem?


 
   
  You know the noise when the earspeakers make or break seal, right? Just to make sure that your distortion problem is not that, which is not a problem.


----------



## AudioCats

Quote: 





kiromn said:


> Dear AudioCats,I have just made the FC class MOD and it sounds fantastic. The only issue is that i could not find the 0.1u 630V, so used only the stock output caps in paralel for this task. Can you recommend some replacement that can be found in stock? Conrad has WIMA caps, but there are several 0.1uf 630v available and i am not quite sure what is the difference.Thanks in advance and admirations for the hard work you have done, so all of us can do the mod.


 
   assuming you are talking about the high voltage rail reservoir..... any high quality cap should work, as long as it is no taller than 12mm and less than 6mm in thickness.


----------



## HeadphoneAddict

Just wanted to toss in that I'm still enjoying my SuperFatCat++ modded SR-001 in my bedside rig. Thanks audiocats!


----------



## Robot Metal

Does anybody know how I can repair a SRM-001 that had a higher voltage applied to it?

 Edit: I have an idea of how to fix it now.


----------



## dogears




----------



## jung

NiZn AA battery outputs higher voltage and current:
http://stereo.50webs.com/


----------



## dogears

^That's the one that came with my Baby Stax


----------



## Archwn

I want to contribute some to this thread. A cure for all baby STAX lovers with unfit/hurting ears, without headband aid - a custom silicone prototype
	

	
	
		
		

		
		
	


	



   

   

   

   
  The sound signature is relatively the same with better bass / mid / image so this is definately NOT a cure for the treble roll-off but I can live with it so far.
   
  Now you can use it anywhere, shake your head (violently?) to your fav tunes, took it out for jogging or even sleep with them in bed.
   
  The best thing for this mod is the comfort. Moreover it costs very little and does not require a skillful hand - but not too clumsy one though.
   
  Hope you will be more enjoy with your baby STAX like I really do enjoy mine. 
	

	
	
		
		

		
		
	


	



   
  AK


----------



## dogears

^That's so cool bro! Wonder where can I get one locally, hmn...


----------



## HeadphoneAddict

The SuperFatCat++ mod was the cure for the treble roll off, at least in my case.


----------



## dogears

I don't mind the treble roll off... but is there a commercial entity that does the SFC++ mod for a fee? TIA.


----------



## Archwn

Quote: 





dogears said:


> ^That's so cool bro! Wonder where can I get one locally, hmn...


 


  Cheers bro. I bet you can get it locally or even do it by yourself.
   
  The process is fairly simple and straightforward. For summary, it's actually your ear impression on one side and your baby stax's impression on the other side simple as that. You visit your local audiologist(bring along your baby stax without silicone tips with you) asking for ear impression, just when the silicone fully filled your ear canal, put your baby stax on and adjust it to a proper position(dont forget to first seal the phone's hole with cotton to prevent silicone entering your phone), wait for few minutes, take it out and repeat the step for the other side (while you enjoy the work of art of your own ear canal on another), take your baby stax out (you can later on attached it back firmly - good thing about silicone impression) put it in the safe place, go back home, use the cutter or sharp knife to cut out the unwant bit, carefully cut out the hole for your sound outlet (I would repeat - carefully and good planning on where to cut and where not to cut is crucial or else you would end up starting the process once again),blend the cut in to get the equal cross section of your ear canal. My pics would be an idea whereabout to cut it and you get a hint hole on your own mold where your baby stax just touch your ear canal and you can start cutting carefully from there.
   
  This video will be an idea for the overall process but Radian silicone cure in 10 mins not few mins. If you having a problem seeing your local audiologist, you can follow the step on this video without a problem. If you have already watched this video, you can skip watching.
   




   
  If I would say something, better tell your audiologist to use less silicone than normal as it is hard to push the baby stax to the proper depth as you can see me wearing the baby stax with 3-4mm thick silicone shown - I wish I had a lot less. Also ask your audiologist for help on adjusting the phone when you put it to the proper depth might be good idea as you can't see where you going.
   
  Quote: 





headphoneaddict said:


> The SuperFatCat++ mod was the cure for the treble roll off, at least in my case.


 


 I have discussed with him and I might try this soon. So the amp's roll off then not the phone's? Wikiphonia said the other way round.


----------



## dogears

^Sadly my ears are too small for the impression to accommodate the driver casing


----------



## marcus1

Way back in the thread it stated that:
   
_"Opamp power supply upgrade, +/- , 9~12V:
 R33, 34 and 35 need to be shorted. The original purpose of these resistors were probably for creating a Pie filter network so small filter capacitor can be used (stock caps were 10uF/16V). The new op-amps (next step) requires a lot more operating current than the stock JRC062L, if you leave R33/34/35 in the circuit they will drop voltage so much that the new opamps won't work. "_
   
I'm using the OPA1642 op-amp (thanks Boris) and am wondering do I have to replace the R33, etc resistors above with other values or would it be OK to short them out?  Is the goal is to bring the voltage (supplied to the Op-amp) down as low as possible to lower the current drawn by the Opamp/amp?  I ask because in post #224 Sclee found that:
   
_"__I installed two AD8620AR, i tested with following and overall current draw is:
 Short R35/R34 15V 360ma
 R35/R34 with 220ohm 12V 345ma
 R35/R34 with 440ohm 9.1V (the stax's default SMD resistance) 320ma"_


   
Also, if I was to change the value of the resistors, I can't figure out which ones to change - all three of them or one or two?
   
Thanks for any help
   
Tim (marcus1)


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## Archwn

Quote:


dogears said:


> ^Sadly my ears are too small for the impression to accommodate the driver casing


 

 Not quite sure where you looking at bro. If you can wear the baby stax with the stock small silicone tips, your ears are big enough for the whole process.


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## AudioCats

1642 draws 1.8mA, while the 8599 in SFC is much higher than that (therefore requiring shorting the resistors in the SFC, otherwise voltages at chip will be too low). I'd say install the 1642 first, see what kind of voltage you are getting at the supply pins. If the supply voltage is too low, parallel something to the resistors until the proper voltage is present at the supply pins ( +/-10~12v ).


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## HeadphoneAddict

Quote: 





archwn said:


> I have discussed with him and I might try this soon. So the amp's roll off then not the phone's? Wikiphonia said the other way round.


 

 The SFC++ sounds very similar to the SR-003 with an SRM-1 Mk2 Pro or an eXStatA amp, and it's definitely not as rolled off as the stock SR-001 Mk2 (or Mk1 which was worse).  It's kinda like a Baby O2, not bright and not dark, and not rolled off.  I don't recall exactly what caps audiocats used, but I seem to recall it was a combination of blackgates and auricaps.  The opamp I think was an AD8599 or something like that.  I'd have to look way back in this thread.


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## dogears

^AD8599 it is.


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## marcus1

Quote: 





audiocats said:


> 1642 draws 1.8mA, while the 8599 in SFC is much higher than that (therefore requiring shorting the resistors in the SFC, otherwise voltages at chip will be too low). I'd say install the 1642 first, see what kind of voltage you are getting at the supply pins. If the supply voltage is too low, parallel something to the resistors until the proper voltage is present at the supply pins ( +/-10~12v ).


 


  Thanks Audiocats
   
  Sorry for noob question but, to be clear in my mind:
  - I would parallel separate resistors across both R34 & R35 to reduce the voltage (if required), but what would I do with R33 - leave it as is or short it out?


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## AudioCats

hmm, I forgot about the R33. try reduce it to the same degree as you will on R34/35  (parallel the same value).
   
  when something is paralleled to the resistors, the final resistance is lower, so the voltage drop across it will be lowered, raising the available voltage at the chip's supply pin.


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## ecodoppler

Hi AudioCats
  At last I have solved the problem of my Stax sr-001 MKII; I sent it to Joynetcafe (Japan) and Stax changed the Earspeakers unit under warranty. Now, it sounds good but I want to modify it as SuperFatCat ( I have put the PCB in a new case, so there aren’t problems of space); however, I’ve some questions:

 AD 8599; how can I mount it on the PCB? Do I need an adaptor? And the directions of the Pins? What is that yellow cap in the photo (post four)?
  N.B. I use four UltraFire 2400 mA 3,7V  as external power supply
   
  2) “add four fast electrolytics directly from the opamps’ VCC/Vdd pins to the round” (post 48). Are they necessary? Have you a photo of the mod?
  3) “H) Add a good electrolytic cap between ground and DC input + (after the switch)”. Its value?
  4) C1: What between BC MKP 0,12uF 63V and Epcos 0,15uF 630V? Or another better brand?
  5) C6-C7: What between BC MKP 0,01uF 630V and Relcap 0,01uF 600V? Or another better brand?
  6) Resistors. May I change them? Or can I leave the original resistors?
  7) C13-14-15-16. How can I replace them?
  8) I think to use Elna Silmic II instead of Black Gate for the other caps. What do you think?
  9) Q15. Really Do I need an heatsink?
  Thank you very much
  Best Regards
  Leandro


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## AudioCats

Quote: 





ecodoppler said:


> AD 8599; how can I mount it on the PCB? Do I need an adaptor? And the directions of the Pins? What is that yellow cap in the photo (post four)?
> N.B. I use four UltraFire 2400 mA 3,7V  as external power supply
> 
> 2) “add four fast electrolytics directly from the opamps’ VCC/Vdd pins to the round” (post 48). Are they necessary? Have you a photo of the mod?
> ...


 
  1) there are already traces and pads on the board for dual opamp. The 001 might be originally designed with soic dual opamp in mind, then somehow changed to the dip straight 8 pin opamps. there are dot marks on the board showing orientation.
   
  2) cap quality affects the sound quite a bit.
   
  3) This one is not super critical, the sound difference is mostly in bass impact, you can skip it if there is no room. 470uf/6.3V will work. The speed is more important than the capacitance.
   
  4) C1 is the input by-pass, any polyprop will work, as loong as it fits.
   
  5) C6 is the hi-voltage rail reservoir, use the largest value (that still fits). C6/C7: use boutique, as fancy as possible, but very few of them will fit, so the BC and soniccap might be your only choices.
   
  6)leave the resistors along, not enough sonic gain.
   
  7) there is no upgrade for C13/14/15/16.
   
  8) silmic will work, but not as good a blackgates. But BGNX is pretty much unavailable, so...
   
  9) USE A  HEAT SINK on Q15! or it can get cooked.


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## ecodoppler

AudioCats
  thank you for your reply. What do you think about the use of Ampohm Paper in Oil Aluminium Foil 0,01 uF 630v in C7-C8? I don't have problem of space, given that I'll put the amplifier in a new case.
  Thank you
  Regards


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## ecodoppler

Hi
  I have modified the Stax SRM 001 as follows:
  C1>>> Solen MKP-FC
  C2, C27 and C28>>> Elna Silmic II
  C3>>> Elna Silmic II
  C17 and C18>>>Nichicon Muse
  Elna Silmic II 470uF 50 V between DC input and ground
  C7 and C8>> Amphon PF-XAL-AL 0,01 uF 630V
  I left the original NJM062L opamps for the moment.
  The sound is simply astonishing: more, more detail and trasparency without lose the touch of warm of the original amplifier. Obviuously, the new caps need break-in but even so the sound is great.
  I use twisted pair Teflon/99,99% pure Silves IC. AudioCats, do you believe I have to make quad-braid Teflon/Silver IC?
   
Thank you


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## kiromn

Can someone help me finding - BC components, MKP420 series, 0.011uF/630v?
  I have installed Panasonics on C7, C8, but the sound is not bright enough for my taste.
  Digikey is selling minimum quantity of 1000pcs !!
   
  Thank you in advance!
  Kiril


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## nick n

Incredible info here! Thanks for this thread!  Mine will arrive soon so looks like I need to do some reading


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## Leefromspace

Digging up this topic even if it isn't really a mod, it still addresses the battery issue. I think I've seen somebody else post around here a picture of a usb portable battery.
   
  http://img547.imageshack.us/img547/9607/bs29.jpg
   
  I found the great Anker slim 2 (4500mAh) which can actually charge at the same time my HTC One and the babystax driver.
  Just got the battery so I'm still testing the setup, but so far so good in terms of battery life.
   
  Next step: finding a better mini mini cable...


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## ericj

Necrobump. 
  
 I finally have comfortable tips on my sr-001mk2 so i am using them at work lately. 
  
 So i am finally actually considering performing some modifications. 
  
 I've got the toshiba opamps, so i think i may keep 'em for now, since i still value portable use. S/N 05870 fwiw. Have there been further advances in ultra-low-power parts here? 
  
 I never had the stomach to do the lithium conversion. I bought the stuff and never did it. Powergenix NiZn AA cells seem to provide just as much voltage, though, and about 6 hours of continuous use before the green LED gets dim. 
  
 A lot has happened in capacitor technology since this thread started. For the electrolytic positions, I think we can go bigger and faster for pretty much every position. So I'm putting some research into that. 
  
 Does anybody know for sure how much headroom there is on the back of the board for smd parts? C3 are power rail bypass caps for the opamps. There are 47uf 35v tantalums that are 3.5mm tall that i could stick there, possibly, if they fit. I could then easily bypass them with a small ceramic or film for noise filtering purposes.


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## vaggbaba

Newby in this thread.
Can we put a 14500 battery with AA together. In order to increase volts. Like 3.7 + 1.2= 4.9 about.
?


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## ecodoppler

Hi
Previously, I used rechargeable four batteries to power my Sr-001 MKII Stax headphones but five months ago I purchased a Baku stabilized power supply with variable output voltage that I use with extreme satisfaction.
Best Regards


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## dogears

Wow! How does your modded baby sound (compared to stock or sfc)?? Very interesting


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## ecodoppler

Hi
Frankly, I don't remember how did the original baby stax sound ( I bought them from Japan in 2012), but, after modding, they sound very, very detailed with good bass. I compare them to my Massdrop Hifiman 4EXX with JDL Labs amplifier.


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## vaggbaba

Can you give  your mod instruction?
Thanks


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## vaggbaba

Can we put a 14500 battery with AA together. In order to increase volts. Like 3.7 + 1.2= 4.9 about?


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## ecodoppler

vaggbaba said:


> Can we put a 14500 battery with AA together. In order to increase volts. Like 3.7 + 1.2= 4.9 about?


Hi
till five months ago I used these batteries (see the attached photo), but, at the moment I use  the Baku BK-1502D+ power supply with great satisfaction.
Best Regards


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## ecodoppler

ecodoppler said:


> Hi
> till five months ago I used these batteries (see the attached photo), but, at the moment I use  the Baku BK-1502D+ power supply with great satisfaction.
> Best Regards


----------



## vaggbaba

Attached photo?


ecodoppler said:


> Hi
> till five months ago I used these batteries (see the attached photo), but, at the moment I use  the Baku BK-1502D+ power supply with great satisfaction.
> Best Regards


----------



## ecodoppler

vaggbaba said:


> Attached photo?


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## ecodoppler




----------



## LinstantX

Hello. I have here is there is stax srs-002 (mk.2) and I'm wondering, is it possible to push battery brand 18650 3.7 v each? Anything happen to the amplifier?


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## CH23

It seems that the original Sanyo 350v 2.2µF caps in my unit are starting to dry out, so i'm looking to replace them with something that will actually fit inside the original unit.

it is my understanding that I shouldn't change the µF, but could go with higher voltage?

what are the better brands still in production?

I might also replace the other caps on the board as well (see pic) should i keep the same ratings, or change anything?


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## kiromn

As all proposed output capacitors are very hard to find, here is what i have found from Farnel.
The soundstage is very nice and open. At first the sound was too warm for my taste, but after 30-40 hours of burn in it settled down.
Here is the part number: MKP1839310631


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## CH23

kiromn said:


> As all proposed output capacitors are very hard to find, here is what i have found from Farnel.
> The soundstage is very nice and open. At first the sound was too warm for my taste, but after 30-40 hours of burn in it settled down.
> Here is the part number: MKP1839310631



film instead of electrolytic, and at 0.01µF instead of 2.2µF?


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## kiromn

This is for the output caps C7 and C8 and this is the right value.


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## CH23 (Oct 1, 2019)

kiromn said:


> This is for the output caps C7 and C8 and this is the right value.



Did you actually read my original post? I asked for replacement for the electrolytic capacitors (which i marked in my photo) because at least one of them has dried out, and then you're recommending i replace another capacitor that, as far as i know, has no issues at all.

The main concern for me is C13, as this shows lower capacitance than C14, C15, and C16

But i'd rather replace those 4 at once, and since it seems that at least one cap has starting to fail, i'd rather try replace all electrolytic caps at once.


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## kiromn

Sorry, i was not answering your post. I had hard time finding the output capacitors for the mod, so i posted a good one from Vishay that is actually in production.
You can check Mouser. They have several brands and types of 2.2uf 350-400v.


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## ericj

yeah, Sanyo doesn't seem to have any retail outlets for capacitors in the usa, but there are many other options. look for something with a long life rating.


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## CH23

ericj said:


> yeah, Sanyo doesn't seem to have any retail outlets for capacitors in the usa, but there are many other options. look for something with a long life rating.



That's why i came here. i could look all day, but I don't quite understand how µF and voltage in capacitors works. voltage I know that higher is better, but µF makes me blank out...



kiromn said:


> Sorry, i was not answering your post. I had hard time finding the output capacitors for the mod, so i posted a good one from Vishay that is actually in production.
> You can check Mouser. They have several brands and types of 2.2uf 350-400v.



Ah I see. your timing was perfect


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## ericj

CH23 said:


> That's why i came here. i could look all day, but I don't quite understand how µF and voltage in capacitors works. voltage I know that higher is better, but µF makes me blank out...



Maybe try these, they have a very long life compared to most. https://www.mouser.com/ProductDetai...Z1n0r9vR22Sv8wqItuvVyLd6GG2MiUoByrrmGJKrj9g==


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## ConnorG

I have been enjoying my 001 Mk2's since getting them about 3 months ago, but feel they are lacking top end and tend to be a little sibilant when pushed.
I was reading somewhere that I would be able to power the 001 Mk2's off of a pro bias energizer by changing the stock cable out for one off of the likes of a SR-003. Would I be able to run the 001's off of a pro bias energizer, or will it melt the drivers? I can't seem to find the bias voltage for the 001 Mk2's (Although it's probably right infront of me)

I am also debating on doing the SFC mod, as many people seem to really like it. Thanks in advance. 

Connor


----------



## kiromn

ConnorG said:


> I have been enjoying my 001 Mk2's since getting them about 3 months ago, but feel they are lacking top end and tend to be a little sibilant when pushed.
> I was reading somewhere that I would be able to power the 001 Mk2's off of a pro bias energizer by changing the stock cable out for one off of the likes of a SR-003. Would I be able to run the 001's off of a pro bias energizer, or will it melt the drivers? I can't seem to find the bias voltage for the 001 Mk2's (Although it's probably right infront of me)
> 
> I am also debating on doing the SFC mod, as many people seem to really like it. Thanks in advance.
> ...


Hey, i have modded the Sr001 mk2 and i am quite happy with it. The output capacitors have huge impact on the sound, so try to find the Vishay ones if you want to stay portable. I am powering the amp with single 14500 Li-ion battery or with wall power supply (a good one)


----------



## HeadphoneAddict

ConnorG said:


> I have been enjoying my 001 Mk2's since getting them about 3 months ago, but feel they are lacking top end and tend to be a little sibilant when pushed.
> I was reading somewhere that I would be able to power the 001 Mk2's off of a pro bias energizer by changing the stock cable out for one off of the likes of a SR-003. Would I be able to run the 001's off of a pro bias energizer, or will it melt the drivers? I can't seem to find the bias voltage for the 001 Mk2's (Although it's probably right infront of me)
> 
> I am also debating on doing the SFC mod, as many people seem to really like it. Thanks in advance.
> ...



I'm fairly sure that the SR-001 can be run just fine with the desktop amp and cable from Stax, same bias and all as I recall.


----------



## Degru

How does one measure the bias voltage of the SRM-001? I anywhere from 0.5 to 1.5V DC when I try to measure it which doesn't seem correct at all


----------



## Area511

Sorry for digging out this old thread but I reactivated my 001 and just ordered all the parts for the mod, I am curios about the schematics but unfortunately the link is not working anymore. Did anyone saved it and can upload again? Thanks very much:



kevin gilmore said:


> For those that might want to see a schematic of what is going
> on here, here is a little something less the power supply.
> http://gilmore.chem.northwestern.edu/stxp.gif


----------



## Area511

I have done the FatCat mod, but unfortunately there is a big volume difference now, left channel much lower volume than right, anyone got an advice how and what to check?
Beside this everything else seems fine.


----------



## ericj

Area511 said:


> I have done the FatCat mod, but unfortunately there is a big volume difference now, left channel much lower volume than right, anyone got an advice how and what to check?
> Beside this everything else seems fine.



I would have to assume that one or more solder joints are sub-par. Did you apply any solder flux? I heartily recommend kester flux pens. 


https://www.amazon.com/Kester83-1000-0951-Soldering-Flux-Low-Solids-No-Clean/dp/B004X4KOWS


----------



## mr.tastycc

Evening fine people, just wondering if the 001mk2 cable srm001 side is somehow fixable, it got bent and now the grounding seems to not be connected properly, everything  sounds quiet and hollow, i have a second cable which now doesn't have the right channel, so would love to fix one of them, any tips?


----------



## AudioCats (Jan 22, 2021)

It might be easier to make a new custom cable instead of trying to splice two partially broken cables into one functional cable.

See if you can find some teflon insulated wire. 28awg should be plenty thin / flexible enough.

if 24awg is not too thick (I think it probably is, though), Mouser part # 55a0111-24-4 is teflon insulated stranded wire, 600v rated, available in yellow and white.


----------



## mr.tastycc

AudioCats said:


> It might be easier to make a new custom cable instead of trying to splice two partially broken cables into one functional cable.
> 
> See if you can find some teflon insulated wire. 28awg should be plenty thin / flexible enough.
> 
> if 24awg is not too thick (I think it probably is, though), Mouser part # 55a0111-24-4 is teflon insulated stranded wire, 600v rated, available in yellow and white.


Making the cable itself isn't an issue, i just need to replicate the damn plug, which idk how to do


----------



## AudioCats (Jan 22, 2021)

sorry, what I had in mind was more of a rebuild, using the ends from the broken cable.  Remove the plastics somehow to expose the metal contacts, then add new teflon wires then cover with teflon heat-shrink.


----------



## mr.tastycc

AudioCats said:


> sorry, what I had in mind was more of a rebuild, using the ends from the broken cable.  Remove the plastics somehow to expose the metal contacts, then add new teflon wires then cover with teflon heat-shrink.


I'll try that out i guess, would like to make a new cable for it tbh, one that doesn't bend to death all the time


----------



## mr.tastycc

mr.tastycc said:


> I'll try that out i guess, would like to make a new cable for it tbh, one that doesn't bend to death all the time


Could probably salvage an old molex cable for it


----------



## Runner 100

krmathis said:


> Excellent work!
> I look forward to the end result. Nicely placed inside the original case, and all.


Hello!
Where can I get an amplifier schematic? The link is currently not available. Thanks in advance!


----------



## CH23

Runner 100 said:


> Hello!
> Where can I get an amplifier schematic? The link is currently not available. Thanks in advance!


I found it online somewhere else, reuploading here:


----------



## Cornerstar39

Does anyone know how big the DC input plug is on the small energizer. I want to power it with a powerbank.


----------

