# My M3 (or Jazper's M3 Monster)



## Jazper

Well I started with the idea of building a cmoy for my girlfriend about 3-4 weeks ago, then went on to decide that she should get something a bit better, and that I should use the opportunity to upgrade what I have. 

 So, I decided (after a week of tossing together options, and pondering over making her an A47 and such) that I'd build an M3. 

 The M3 has become something of an obsession, the amount of work I've put into it is rediculous at this point and people have begun to ask me what I'm doing/how I'm doing it/what components I use etc etc etc.. so that's what this thread is going to be about. I don't promise that it'll be interesting, but it'll be factual. 

_The power supply:_ 

 I started out trying to make a basic m3, was going to buy a STEPS with it to begin with, then after long winded conversations on msn with Dakiller we came upon this design:
http://www.diyaudio.com/forums/showt...threadid=56106 

 I bought a 20VA toroidal from the local electronics store and the necessary parts

 I made some substitutions on the parts (LM317, 5500uF Low ESR caps, LED/Resistor -10k on the output, 5w bleeder - wire wound resistor rather than 2w metal film) and used 1w ceramic resistors. I also only used half of the design. When building it I just built it on plain perfboard (just copper circles around small holes) 

*Lesson 1 :* always check your resistor values - when I first powered up I got 33.5v which was way too high, I was aiming for 28.15-28.6v (yes, it needs to be that precise - I'll tell you why later), needless to say much resoldering and calculations later I managed to get about what I wanted, after I put some load on the end of it.

 When this worked ok I left it and began speccing out parts for the M3.

 All up this cost about $25AUD (without the transformer)

 This was about the time I decided ok I want something that is somewhat unique.


_The m3, part 1:_

 First step I made was to decide on the elec capacitors on the m3, I looked at cerafines, nichicon muse, black gates, panasonic fc, and even just plain old nichicon Low ESR. After much pondering and thought I decided that the best value for money overall is the SILMIC IIs in terms of having something that is both boutique and something that most people don't use. You always hear about people using cerafines or black gates, but never SILMICs.. 

 The crucial part here was money, or lack of it, I'm a student who works on and off, so every cent counts, or counted at this point, so I asked amb about using 35v caps throughout the M3, after getting the ok, I ordered them all from http://www.audio-cube.nl/elna.htm 

 From there I just got the excel file from amb's website and started going through all the EXTRA parts I needed (listing them in the excel file.) 

_I should mention that I'm quite happy with the choices made in the excel file regarding parts from mouser - all are high quality and the only modifications I've made so far are the alu caps and I'm thinking about possibly changing the polyester caps for polypropylene however I'm not keen on having things off board and doubt having them will make much difference. _

 At the onset I'd decided I wanted to use as much power as I could get into the amp, I plan to run 28v with relatively high quinescent current on the mosfets (well as per the settings on amb's page). The reason for this is so I can drive most anything from the amp without issue. 28.5 is the key voltage because I wasn't sure whether or not I wanted to roll opamps, I know that I like the opa series chips (637/627) but I might like to roll some AD8610s sometime. In the big M3 construction thread amb states that the voltage drop across the m3 is 2v, so 28.5v puts this at 26.5v just under the max rating(27v) for the AD8610s 


 This is about the time I started looking at cases 

_Cases/enclosures:_

 I was looking for something that was about 200mm x 300mm for about say 5 days straight, but have still come up short. Hammond have something but it cost a fortune to get shipped over here and looked a bit foul, everyone keeps saying put it in a 1u rackmount... anyhow I haven't settled on a case yet, getting anything from par-metal detracts from the exclusivity of this particular M3 so I'll probably look at something more unique, perhaps part wooden, perhaps not, I know I'll have to shield the case if I use wood. Then again if I could find something half decent that wasn't huge I'd be happy. 

 The only requirement is that it somewhat fit on the top of my computer case, for convenience reasons. 


_The power supply, take 2_
 After much deliberation and talking with family members I came to the conclusion that I should look at doing something different, nay special with this M3, so that I might sell it for a higher price later (if I ever wanted to sell it...  ) 

 So I started looking into different things I could do to improve the m3's design, I toyed with removing the rail splitter and having a dual rail power supply, using uber boutique resistors (with 0.001% ratings) and other ideas before I came upon (again on heavy consultation with Dakiller) that the best way to improve the design, and see a net gain in quality would be to move away from the whole lm317 power supply design and go with something better, the modified jung super regulator. 

 At this point I was sick of messing with protoboard, I wanted something that worked and was laid out on a nice pcb, I found one particular type that was on the diy audio forums that was a possible but they were out of stock so I decided to look at what our resident expert in SMD here (Peranders) had in stock. 

 Dakiller warned me that it'd cost a lot to get a board from him, but I persisted, I like P-A's designs. I settled on his JSR03 design( http://home.swipnet.se/~w-50719/hifi/jsr03/index.html ), inquired, bought and then started talking to him about parts. (More info here: http://www.sjostromaudio.com/phpBB2/viewtopic.php?t=14 - note I use the nick Keljian over there)

 A few of the parts were obsolete and needed replacements, and some weren't able to be sourced easily, also I wanted to run higher voltage than the JSR03 components can handle (stock) so a few modifications were necessary (notibly alu capacitor voltage ratings - see bom) 

 After using his forums I've substituted quite a few parts for parts available at mouser, but the notible ones are the RN60D vishay dale resistors, the vishay/Roederstein polypropylene capacitors, and the transistors (as some were unavailable). The polyprop cap leads may need to be bent a bit to fit but being axial leaded they are easier to fit than the square brick wima caps which would have to be off board.

 (note R8, r9 and r7 are 2k15, 681R and 511R respectively to get just over 28v)

 The voltage reference given in P-A's stock part list is LM431, he says the LM329 is better, so based on that, that's what I'm going to use.

 Now P-A's design is beautiful, but it doesn't include a bridge rectifier or smoothing caps, My default choice for caps is nichicon UPW, but it turns out that panasonic FM are cheaper and I'll be ordering from digikey anyhow so they'll be what I use. I'll put these together with the rectifiers on protoboard. 6x1000uF 50v

 I've chosen panasonic FM for a few reasons, the main one is that the price is right(less than nichicon), but also the impendance is lower than the Nichicon UPW. I'm hoping that C4 and C12 on P-A's design can be 150uF (as panasonic FMs don't come in 100uF from digikey, and yeah I could use FC instead but I'd rather not as the impendance is much lower on the FM)

 As for rectifier diodes, diyaudio people seem to like the MUR820, which is overkill but cheap enough to use, so I plan to use a reasonable clone of it. 

 I've also added good hookup wire and silver solder to the list of things to buy because I figure why not go the extra mile when I'm going that far with everything else?

 As of today (14-6-05) I haven't made the final order from mouser or digikey, but I've bought everything I need from amb, audio-cube, and peranders. Barring final changes, I may make the huge order tomorrow or the day after. 


 Anyhow, I'll leave it there for now and keep this thread updated.

 The bom I'm working from is attached to this message, it is a bit messy (will tidy it up later), but yeah it's all there, hours and hours and hours and hours of work worth of it. The equations on the second page are for the resistor calculations.

 Any questions, I'll do my best to answer.


 PS. Thankyou everyone who's helped so far especially P-A and my girlfriend for their patience and Dakiller for all of his valuable advice, much appreciated.

 Jaz


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## Jazper

changed rectifier diodes for RHRP860 (made by harris) soft recovery, >30ms .. expensive too :S but you get that. Ordered locally at RS

 btw it should be noted that I know the input to the regulator will be about 33.5v because of the mistake I made earlier with the first power supply. BUT I'm prepping it for 50v in just in case of voltage spikes

 I also know that when set to 28.5v the LM317 will output 29.5-29.7v unloaded. (again based on the other power supply design)

 I'm hoping that the inrush current charging the 8000uF worth of caps (straight after the rectifier diodes) won't blow the transformer.. though if it's just a spike it should be ok

 150uF should be fine, so I'm using panasonic FM & FC for the regulator


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## Jazper

well on completion of a project I usually look back and see what kind of things I could do differently, this project is no exception so here's what I would have done differently (about the electronics) 

 1. Read peranders' website more thoroughly regarding the JSR03
 I missed some valuable tips because I didn't, but the problems have been corrected. Plus I wouldn't have ordered all the parts I did.

 2. Checked each component against the schematic diagrams - would have avoided the trimmer problem I had early on

 3. Checked lead spacing on all of the parts I changed or intended to change - would have not had to spend more on components.

 4. Read datasheets for each of the active components and compared to the original component choices- would have debugged the LM329 problem earlier. 

 5. Went a little overkill on the VA rating on the transformer, rather than getting the bare minimum - cost was an issue, but at the same time I didn't do enough research into the amount of power the thing would draw, and the voltages I'd require. 

 6. Connected everything on first powerup - not connecting the led meant when I slipped and shorted Q5 on the m3 board meant that I killed them even though the power was off, the caps still held a charge

 7. used browndog adapters from the start - no mucking around with trying to solder on to chip sockets.

 8. if I have an LM317 in the design or anything in a TO220 package, expect heat to come off it - would have been helpful so I didn't burn my finger on the d44h11 in the JSR03 (which is running at 70C) 

 9. got heatsinks with pins for the mosfets, (which I could have done cheaply, locally) so I could solder them to the board

 10. used vishay dale 1/8w resistors in the jsr, they are rated to 1/8w but can handle 1/4w at a pinch, so would have been fine. 

 11. used wima or avx caps for the polyester film caps rather than no brand for the jsr (though I don't think this would have made much of a difference at all) 

 12. used 6000uF as I originally intended for dc smoothing rather than 8000uF - I've settled on 7000uF but it would make more sense to go less overall, I don't need as much as I have. 

 13. read about lead spacing of the silmics and looked at other options, they are simply too big for the m3 board, perhaps a slightly lower capacitance would have fit much better. (say 220x9 rather than 330x9?) 

 14. bought more terminal blocks from mouser - I've used 3 in the design, broken one in making it all, would have been better if I bought about 6 or so, just so I had spares

 15. checked capacitors with a bleeder resistor before soldering - sparks are bad mmmkay?

 16. Selected the fast switching, soft recovery diodes to begin with.

 17. considered the tensile strength of the hookup wire I was buying - the core has snapped several times due to flexibility issues and such

* How it sounds *

 note: I listen to a wide range of music on this thing, everything from greenday to vivaldi, through usher, van halen, to live, to louis armstrong.. so it's an overall view 

 As for how it sounds, it's fun! - non technical easy listening and fun to listen to, I think that's the best way to describe it. It is well refined for critical listening however it also has a warm smoothness to it, that the dtpakiller amp doesn't have. It is a bit dark with the opa637s, but the AD8610s are a nice match for it (ironically as the opa chips were the ones that I generally prefer, hence the hassles getting them earlier). The AD8610s in comparison give the amp "a shot of adrenaline" and really make it come alive, indeed they are livlier than the more laid back opa637/627 combination. Though I feel the opa combo would be better for classical, so it comes down to music preference as to which is better with this amp. 

 Warm is a good way to define the amp, it doesn't have the bass slam that I loved from the dtpa, but that's not to say the bass is lacking - overall it's less fatiguing to listen to. Easy listening is another way to describe it, it's smooth, doesn't have the sharp edges I'm used to. The bass boost is subtle, but there. 

 I've said it's smooth, but don't take that to mean dark, the treble is nice and rounded, almost honey smooth, female vocals are a delight on this amp(definately not piercing). It doesn't feel electronic. It feels fluid, liquid, almost organic in the way it sounds. 

 I'm no audiophile and definately not an electronics engineer, but those are my thoughts on it. 

 Jaz


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## skyskraper

perhaps one of the thlaudio cases would be the go? i mean a rack (it needs 1ru btw) works for me because i have one on my desk with other gear in it, but i can see how you may now want one.


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## Jazper

Quote:


  Originally Posted by *skyskraper* 
_perhaps one of the thlaudio cases would be the go? i mean a rack (it needs 1ru btw) works for me because i have one on my desk with other gear in it, but i can see how you may now want one._

 

What do you mean it needs 1ru? 1ru is about 450x 480cm, which is huge, no way does it need that.


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## skyskraper

doh, morning typo, it needs to be 2ru, as in height. 1ru isnt tall enuff to fit the mosfet's heatsinks in. i believe one rack unit is 44mm.


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## Jazper

Quote:


  Originally Posted by *skyskraper* 
_doh, morning typo, it needs to be 2ru, as in height. 1ru isnt tall enuff to fit the mosfet's heatsinks in. i believe one rack unit is 44mm._

 

These are the 1U dimensions - I assure you that 1.5" heatsinks will fit in there.

 Dimensions in mm (all units 482.6mm wide):
 1U
 Panel Height 43.7
 Cabinet Height 38.7
 Cabinet Depth 245


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## skyskraper

1.5" = 38.1mm
 internal space = 38.7mm

 lets not forget the thickness of the board and the lead ends sticking out the bottom. 

 and room for the heatsinks to breath (whats the fun in not biasing above the bare minimum? 
	

	
	
		
		

		
			





 )


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## Jazper

Quote:


  Originally Posted by *skyskraper* 
_1.5" = 38.1mm
 internal space = 38.7mm

 lets not forget the thickness of the board and the lead ends sticking out the bottom. 

 and room for the heatsinks to breath (whats the fun in not biasing above the bare minimum? 
	

	
	
		
		

		
		
	


	




 )_

 


 Spose, but I'm open to cutting the case and having the fets stick out of the top so it's a non issue


*Update*
 I've just ordered the rest of the parts, the amb order arrived in the mail today (thanks amb!)


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## skyskraper

hehehe ok have fun, i cut the top of one of these cases once, theyre a pita, i had to go to a friends work to use their equipment, working with steel isnt fun


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## Jazper

Quote:


  Originally Posted by *skyskraper* 
_hehehe ok have fun, i cut the top of one of these cases once, theyre a pita, i had to go to a friends work to use their equipment, working with steel isnt fun_

 

 A friend of mine has a dremel, I'm sure it won't be too hard. We'll see though. 

 Note: I'm probably going to use 8x1000uF caps for the power supply rather than 6x due to ordering limits on digikey


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## skyskraper

the dremel will get chewed alive, try drill with HSS bits then use HSS cutting wheels on a power drill (proper one, not cordless).

 why order from digikey when you can get heaps of caps and stuff from RS and Farnell for less then the cost of order + shipping to aust?


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## amb

Quote:


  Originally Posted by *Jazper* 
_Note: I'm probably going to use 8x1000uF caps for the power supply rather than 6x due to ordering limits on digikey_

 

If this is after the regulator, be warned that it's probably too much capacitance for the LM317. On power-up the charge-up current will be very high, and the LM317 would probably shut down (or blow up). At the very least, go with a LM338 regulator, or use less capacitance. If these are intended for the C7 capacitors on the M³ pcb, the D1 diode (1N4001) is not rated high enough to handle the charge-up current from 8000uF of capacitance.


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## Jazper

Quote:


  Originally Posted by *amb* 
_If this is after the regulator, be warned that it's probably too much capacitance for the LM317. On power-up the charge-up current will be very high, and the LM317 would probably shut down (or blow up). At the very least, go with a LM338 regulator, or use less capacitance. If these are intended for the C7 capacitors on the M³ pcb, the D1 diode (1N4001) is not rated high enough to handle the charge-up current from 8000uF of capacitance._

 


 Nope, this is before the regulator 
	

	
	
		
		

		
		
	


	




 thanks for the advice though. 

 C7 caps are 330uf 35v Silmic II x 9


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## Jazper

Quote:


  Originally Posted by *skyskraper* 
_the dremel will get chewed alive, try drill with HSS bits then use HSS cutting wheels on a power drill (proper one, not cordless).

 why order from digikey when you can get heaps of caps and stuff from RS and Farnell for less then the cost of order + shipping to aust?_

 


 cause the chips required for the JSR03 are not available here from RS or farnell. 

 Most parts are coming from mouser, the power supply caps + extra chips are coming from digikey.


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## skyskraper

thats fair enough then 
	

	
	
		
		

		
			





 i hate how there are just those few things RS and Farnell and Xon don't have, they always end up being the ones u need and incorporating shipping theyre the priciest


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## Jazper

Quote:


  Originally Posted by *skyskraper* 
_thats fair enough then 
	

	
	
		
		

		
		
	


	




 i hate how there are just those few things RS and Farnell and Xon don't have, they always end up being the ones u need and incorporating shipping theyre the priciest 
	

	
	
		
		

		
		
	


	


_

 


 well there are two things with it, first of all I wanted to use vishay dale resistors throughout, and second I wanted panasonic FM or nichicon UPW caps for the power supply. I bought overseas mainly because of brands/quality/performance. I want the best I can get within reason.


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## skyskraper

u can get those caps locally RS and Farnell have them. the only pita is the vishay dale's. but i use philips resistors, theyre quite nice, i couldnt hear a difference with them to VD's.


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## Jazper

at this point I'm considering a 1u rackmount and fitting an acrylic window in the top .. it'd be easier to cut if nothing else


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## amb

Quote:


  Originally Posted by *Jazper* 
_at this point I'm considering a 1u rackmount and fitting an acrylic window in the top .. it'd be easier to cut if nothing else_

 

And you could show off the pretty p-o-r-n inside.


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## skyskraper

i was thinking about getting a nice honeycomb mesh for mine, could be an option for you, havent been to the local Al supplier lately but im sure they'll have something suitable


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## Jazper

Quote:


  Originally Posted by *amb* 
_And you could show off the pretty p-o-r-n inside. 
	

	
	
		
		

		
		
	


	


_

 

if I did that I'd have to play waka waka 70s p-o-r-n style music on it, it's too good for that.


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## peranders

Quote:


  Originally Posted by *Jazper* 
_<placeholder for follow up>_

 

Don't forget that you have one week at the most because you have a time limit on editing.


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## Jazper

Quote:


  Originally Posted by *peranders* 
_Don't forget that you have one week at the most because you have a time limit on editing._

 


 no big deal, I can make posts here


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## peranders

Quote:


  Originally Posted by *Jazper* 
_As for rectifier diodes, diyaudio people seem to like the MUR820, which is overkill but cheap enough to use, so I plan to use a reasonable clone of it._

 

This diode isn't especially good. The type is known and this is enough I think. I'll believe you have 1000's of different types to choose from. Compare the situation of recommended opamps. We have AD8610, AD797, OPA134, OPA627 and a couple of more but in real life there are 100's of more or less suitable types.. so this isn't any absolute science.


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## Jazper

(post deleted)


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## peranders

Quote:


  Originally Posted by *Jazper* 
_Now P-A's design is beautiful, but it doesn't include a bridge rectifier or smoothing caps, My default choice for caps is nichicon UPW, but it turns out that panasonic FM are cheaper and I'll be ordering from digikey anyhow so they'll be what I use. I'll put these together with the rectifiers on protoboard. 6x1000uF 50v_

 

In a not too far future I will have a complete super power supply, some time in the fall maybe.
http://www.sjostromaudio.com/hifi_fi...0schema_p1.pdf
http://www.sjostromaudio.com/hifi_fi...0schema_p2.pdf
http://www.sjostromaudio.com/hifi_fi...0schema_p3.pdf


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## Garbz

/edit: Nope simply wrong button 
	

	
	
		
		

		
		
	


	




 New thread I wanted


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## Jazper

Quote:


  Originally Posted by *Garbz* 
_ <snip>_

 


 wrong thread?


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## peranders

Quote:


  Originally Posted by *Jazper* 
_The voltage reference given in P-A's stock part list is LM431, he says the LM329 is better, so based on that, that's what I'm going to use._

 

First we are talking about industrial parts so if the industry wants to pay more for something it must add a certain value.

 So in the case LM329 and LM431 there are differences'

 LM329, 199, 399 is no precision part when it comes to absolute accurecy. The major good parameter is low noise and it's also mentioned and specified in the datasheet although pretty rough, 7-100 uV! The very good thing about LM329 is very low temperature coefficient which is rather unimportant in audio.
 The bad thing (sometimes) is that it can't be adjusted.

 LM431 hasn't got any noise data but it is higher, still in real life with LP-filter the regulator has pretty low noise, way better than needed in most cases.

 So if you want more than 6.9 volt and a very temperature stable output voltage LM329 is OK. If you want to save same money and in the same time want voltages från 2.5 V and up and also want to be able to tune the voltage in an easy way LM431 is to prefer.

 Strict technically LM431 together with some additional parts is way better than any regular 3-pin regulator which is normal in high-end!

 .... so if you want more than 6.9 volt LM329 is excellent but LM431 is quite enough.


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## Jazper

Lesson 2: always check the browndog adapter you're soldering to :S 

 after receiving some browndog adapters from a headfi member that were unmarked I soldered a pair of smt opa 637's to them. little did I realise that the adaptors are converters for use with single opamp chips to convert to dual, after trying desperately to desolder one of them after realising this fact, I've successfully killed a 637 (OUCH $$$) so.. while I do have one more 637 spare it still means I'm going to be a chip short (unless by some miracle I desolder the other) and it's going to take a lot longer before I'll have this going at this rate :S 

 :S

 anyone wana swap a browndog 2x with 1x 637 soldered to it for a dip8 version of the chip?

 update: pondering biting the bullet and buying an 8610, considering I have 2 kicking around..


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## Jazper

skyskraper to the rescue - sold me a 637 relatively cheap 

 back in business


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## Jazper

I don't believe it.. I managed to desolder the other one.. *shrugs* guess I was just too rough with the first. We live and learn


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## Jazper

Well good news on the case, my sister's boyfriend works as a toolmaker/turner/fitter for a racing team and has offered to build me a case from sheet aluminum, so I guess I will actually get a custom case


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## Jazper

well, a few more hiccups with the build, 

 first that I didn't order enough caps for C2/C6 (so I had to order them locally - and it cost a bit). However I got something better (WIMA, which weren't in stock at mouser)

 Second the 35v/330uF SiLMICS are friggin huge, so much so that they've taken some serious bending to fit the board, so instead or a nice neat row of caps, they're a bit skewed in places. 

 Thirdly I tried weldingP) the surface mount chips to chip sockets, but failed miserably after burning my hands many a time, so browndogs are on order. ETA when tangent sends them *shrugs* 

 my digikey order still hasn't made it through the mail yet.. so I can't complete the power supply board, but the amp board should be complete tomorrow or the day after. I'd be able to test if it weren't for the opamps... 

 anyhow.. just keeping you all posted..

 Jaz


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## Jazper

I'm having trouble with the JSR03, the parts are just too cramped together so it's very difficult to fit them in the board, the RN60D vishay resistors don't fit normally so I'm tombstoning and the polyprop caps are a real pain (some will HAVE to be polyester). overall it's very very fiddly so far.. so we'll see how I go. I'll persist but it ain't going to look pretty.


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## peranders

One way to find out if it's worth the trouble with audiophilic parts is to build the regulator with "original" parts first. If you then are satisfied you know from where you are going when you start tweaking.

 At this very moment you don't know if the regulator will work proberly at all. Remember that this regulator is a wibeband device so it requires some consideration when it comes to choices of parts.

 The whole purpose of a super regulator is to let the active parts do the main task in forming a very low impedance and a very low noise voltage source.


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## Jazper

well an update, be it small












 Pictures of the build first - I am aware the caps are "wonky" but they don't fit neatly. (note they're 330uF 35v silmics) 

 Also I'm aware that one of the trimpots on the m3 is missing, during the whole desoldering exercise I broke one of the leads, another should be here tomorrow or monday

 Opamps - I got some TL071s today, will be trying them when i've got the final pot. I have some AD8610s and some 637/627s but they're all SMD, so I'm waiting on browndogs

 progress on the case has started, I've toyed with a few designs and it'll be worthwhile when its done. 

 The JSR 03 (the regulator) is outputting 17.95v exactly(when I'm feeding it 29v from psu mk1), so something needs to be fixed or changed in the design there, I've been using psu mk1 (the one I described earlier) for m3 testing up to this point.

 Made some changes to JSR03 - (some components removed now)


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## peranders

Remember that you will need 33 volts in at least if you want 28 volts out. You should have 5 volts more than you want out.


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## Jazper

Quote:


  Originally Posted by *peranders* 
_Remember that you will need 33 volts in at least if you want 28 volts out. You should have 5 volts more than you want out._

 


 with 32.2v in (unregulated) the voltage is the same (8.27v)


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## Jazper

so close.. yet sooo far







 The m3 is drawing 309mA. Quiescent current ~130mA 

 The JSR seems to drop out of regulaton as soon as the load comes on it (or shortly after) and it hits about 24v .. give or take

 still troubleshooting with P-A

 you might also like to know that the big psu caps are 1000uF panasonic FM/50v and they're the same size as the SiLMIC IIs which are 330uF/35v


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## peranders

You must also check your raw voltage. What do you have really? It must not go under 34 volts. When you have 26 volts out, what have you in?


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## Jazper

Quote:


  Originally Posted by *peranders* 
_You must also check your raw voltage. What do you have really? It must not go under 34 volts. When you have 26 volts out, what have you in?_

 

will check after lunch, but I'm pretty sure it's 34.2v

 I'm looking for only 28v out..


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## peranders

Quote:


 The default recommendation is a regulated 24V DC power supply, that could support 0.5A of continuous output current. Ripple and noise should be as low as possible, 1mVp-p would be the maximum tolerable. 
 

From AMB's site.

 Why do you have to have more? I see no reason for it when you have a 24 volt AC at disposal.


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## Jazper

Quote:


  Originally Posted by *peranders* 
_From AMB's site.

 Why do you have to have more? I see no reason for it when you have a 24 volt AC at disposal._

 

Voltage swing..

 but .. when I tried the 30V ac/500mA transformer, the results were the same..

 it looks to me like the problem is the JSR.


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## peranders

Quote:


  Originally Posted by *Jazper* 
_will check after lunch, but I'm pretty sure it's 34.2v

 I'm looking for only 28v out.._

 

If you don't have an oscilloscope you must be on the safe side and if you have DC you must have 5 volts at least and if you include ripple you must have up to 10 volts if you also include variations on the mains voltage. Still WHY do you have more than 24 volts? In theory you will get 1 dB more out which you don't hear.


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## Jazper

Quote:


  Originally Posted by *peranders* 
_If you don't have an oscilloscope you must be on the safe side and if you have DC you must have 5 volts at least and if you include ripple you must have up to 10 volts if you also include variations on the mains voltage. Still WHY do you have more than 24 volts? In theory you will get 1 dB more out which you don't hear._

 

I'm not trying to get 1db more, I'm trying to set it up so I have no problem driving high impendance phones, as well as being able to drive low impendance phones.

 regardless.. I'll run the numbers for the resistors for 24v..


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## peranders

Quote:


  Originally Posted by *Jazper* 
_Dakiller warned me that it'd cost a lot to get a board from him, but I persisted, I like P-A's designs._

 

All pcb's goes with a reasonable amount of support so if a board goes for 5-7 USD plus support plus all development time, how much is left? Therefore it must cost a bit more.


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## Jazper

Quote:


  Originally Posted by *peranders* 
_All pcb's goes with a reasonable amount of support so if a board goes for 5-7 USD plus support plus all development time, how much is left? Therefore it must cost a bit more._

 

good call


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## peranders

Quote:


  Originally Posted by *Jazper* 
_I'm not trying to get 1db more, I'm trying to set it up so I have no problem driving high impendance phones, as well as being able to drive low impendance phones._

 

Still, it's only about dB's. Have you asked the M3 team about this? You don't seem to see the design problem here?

 1 Do you need 10-11 V peak to reach desired volume WITH used headphones?

 2 Is the volume not enough with 10-11 V so you'll need 12-13 V? => 1 dB more?

 You must always think in dB's when it comes to headroom calculations.


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## Jazper

ok.. I've got resistors to take it to 25.77 (but nothing closer that will keep R7 at 500ish and the voltage at 24ish


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## peranders

You can disregard this at the moment. This is only for minizing the temp drift and for optimizing properties over 1 MHz. The main thing is to get the regulator working at < 20 kHz.


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## Jazper

sorry PA, I don't follow, I said the resistors I have to change R8 and R9 (on JSR03) are 
 approximately 1800 and 680 ohms. you suggested changing the voltage to 24v, that's the closest I have on hand. 

 right now I'm disregarding the fact I'd prefer to run a bit higher voltage.


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## Jazper

Quote:


  Originally Posted by *Jazper* 
_sorry PA, I don't follow, I said the resistors I have to change R8 and R9 (on JSR03) are 
 approximately 1800 and 680 ohms. you suggested changing the voltage to 24v, that's the closest I have on hand. 

 right now I'm disregarding the fact I'd prefer to run a bit higher voltage._

 


 changed to 25.7 - unloaded..
 with load.. 23

 same as before


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## Jazper

IT'S ALIVE!!! 

 changed the toroidal for a much bigger one (20->160VA should be noted that I went 160 because the next step up (80) was only $5 less than the 160, and the dimensions were very similar) and ... wow...

 with the little listening I've done so far, I have to say the ad8610s do a better job in this amp than the opa637s for all together listening pleasure, however the 637's do a better job of classical.

 will post more when I have it (the amp currently looks the same as the pic above, but a case is coming..


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## Jazper

http://www6.head-fi.org/forums/showt...07#post1440407

 (updated post)


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## Jazper

After continued frustrations and slip ups (which peranders, and myself attribute to eagerness and shakey hands 
	

	
	
		
		

		
			





) that caused no end of pain troubleshooting the JSR03, I've moved to a derivative of the first power supply that I built based on the diyaudio design, I've used silmic and panasonic caps throughout (for electrolytic), bypassed with polypropylene on the smoothing/holdup caps. 


 Changes to the original design(note I'm only using half of it): 
 (original design here: http://www.diyaudio.com/forums/show...&threadid=56106 )

 B1 is RHRP860 (made by harris)
 Removed R1
 C1 is 7000uF (panasonic 1000uF/50v FM caps)
 C3 is a no brand polyester cap
 C5 is 100uF (rather than 47uF) panasonic 100uF/50v FM
 R7 is 27ohm (I think the original value may have been a mistake.. ) 
 C9 is 47uF/35v silmic II
 R3 is 47R
 R5 is 1k
 used LM317T rather than 338 - will be switching on/off from the mains

 added:
 .1 uF (100nF) vishay polypropylene cap to bypass the power caps
 added 10k resistor + red LED on the output so I could tell when it's on and so that there is always some load on it to drain the caps on poweroff. 

 Notes: 
 R5 gets pretty warm (I'm running 1/2w resistors, but they're the size of 1/4w resistors, I may change it for 2w when I get the chance)

 Vout is approx 26.7v

 Sonically, I can't hear the difference between it and the jung(aside the fact that the amp sounds a touch punchier now-which is a good thing), so I must be doing something right or my ears just aren't tuned enough.

 One note with the M3 is that it seems to sound much better after it's been warmed up for an hour before listening, before that it seems a bit slower.

 Will post pics when I can, but this design is much simpler than the JSR and I'm much more comfortable with it.


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## Jazper

(action shots- ignore mess in the surrounding area.. )











 case is still on its way...(and yes that is an LM317 under all those heatsinks  )


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## peranders

Quote:


  Originally Posted by *Jazper* 
_Will post pics when I can, but this design is much simpler than the JSR and I'm much more comfortable with it._

 

It's a pity that you failed here but when I'll got the time later on I'll check especially on a 24-30 volt version. I can't really explain what troubles you did experience. To be really sure that everything is working alright you'll need at least an oscilloscope. I have tested more than 500 mA out with good performance. I think it's a bit mysterious why you did get a heavy voltage drop. This may have to do you transistor gain, supposing all parts were in the right place.

 I'll let you know how I'll succeed and we can surely work something out with your killed pcb.


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## Jazper

Quote:


  Originally Posted by *peranders* 
_It's a pity that you failed here but when I'll got the time later on I'll check especially on a 24-30 volt version. I can't really explain what troubles you did experience. To be really sure that everything is working alright you'll need at least an oscilloscope. I have tested more than 500 mA out with good performance. I think it's a bit mysterious why you did get a heavy voltage drop. This may have to do you transistor gain, supposing all parts were in the right place.

 I'll let you know how I'll succeed and we can surely work something out with your killed pcb._

 


 Thanks 
	

	
	
		
		

		
		
	


	




 The tweaked out m3 draws close to 500mA (and I'm pretty sure it spikes over that occasionally). The killed pcb is in a sorry state, pads are messed up, tracks lifted, really to continue that path I'd need to buy another pcb and start desoldering (and buy some _more_ components)

 I've been thinking about this, and one possible solution is to build 2 JSRs to put out +-13.5v, one negative, one positive and share the load over them (connect positives, leave out ground) - something like the JSR04.

 the transformer I have has dual windings


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## peranders

500 mA class A for a headphone amp seems to be much. Have you measured anything like with Rightmark Audio Analyzer? Maybe you are getting side effects if the design wasn't made for that much bias?

 If you use +- 13.5 volts I think you are ruin a bit the "soul" of the amp. The soul was to have a ground channel which means that you use a single voltage.


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## Jazper

Quote:


  Originally Posted by *peranders* 
_500 mA class A for a headphone amp seems to be much. Have you measured anything like with Rightmark Audio Analyzer? Maybe you are getting side effects if the design wasn't made for that much bias?

 If you use +- 13.5 volts I think you are ruin a bit the "soul" of the amp. The soul was to have a ground channel which means that you use a single voltage._

 

current draw for the M³ would be approx: 

 140mA per mosfet pair (420mA) (quiescent)

 +opamps (7mA each - opa637/627 combo) (21mA)

 + LED (10mA) 

 + various transistor stages (say 15mA ) 

 Quick maths tells me thats approx 466mA

 I haven't used rightmark (I don't have a the hardware to measure it) but on amb's site he mentions you can increase the quiescent current and quite a few people have reported better bass response from it. The mosfets are running about 45C (ambient 25~ C ) so it's not cooking them.

  Quote:


  Originally Posted by *amb* 
_
 So, for a 32 ohm load, if we want to achieve, say, 6Vp-p (3V average) without dropping out of class A, then that's 3V / 32 ohms = 94mA. One half of that is ~50mA. Give it a healthy bit of extra margin and let's say we run at 80mA, with +/-12V rails, then each output MOSFET will dissipate 12V * 0.08A = ~1W. This is for the left and right channels. Since the ground channel has to potentially sink or source twice the current return (such as in the case of a mono signal), then the ground channel should be biased to twice that amount. If you want to get even higher output swings into 32 ohm load or if you want to run even lower load impedances with the same voltage swing, then the quiescent current must be increased or you drop out of class A at high volumes.
_

 

(I'm using ms-1s - 32 ohm headphones)


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## amb

Quote:


  Originally Posted by *Jazper* 
_...
 (I'm using ms-1s - 32 ohm headphones)_

 

But do realize that when I mentioned 6Vp-p output, that is going to be insanely loud in your headphones (in fact, it may be enough to damage it). Under normal listening conditions you will not get anywhere close to that much voltage swing with low impedance cans. So, even the "standard" 80mA quiescent has plenty of margin. Only when you use something low impedance and ridiculously inefficient would you ever drop out of class A.


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## Jazper

Quote:


  Originally Posted by *amb* 
_But do realize that when I mentioned 6Vp-p output, that is going to be insanely loud in your headphones (in fact, it may be enough to damage it). Under normal listening conditions you will not get anywhere close to that much voltage swing with low impedance cans. So, even the "standard" 80mA quiescent has plenty of margin. Only when you use something low impedance and ridiculously inefficient would you ever drop out of class A._

 

good point, I'll turn them down a bit. (turned down to 110mA - which would make the amp draw 90ma less .. 380 mA or so I'm guessing.. )


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## peranders

I have just tested my Super Regulator with 25.30 V as output.

 Used parts, exactly as the basic design with the following changes:

 T4 D44H11
 T1, T6 BC560C
 IC2 LM329 (6.830 V)
 R3 2k2
 R8 2k7


 Load, current, min voltage in
 40 ohms, 625mA, 28.48V min
 30 ohms, 833mA, 28.80V min
 20 ohms, 1250mA, 29.42V min

 Note that min voltage in is really min voltage so if you have ripple you must add it. If you don't are able to verify how much ripple you have got you must have some safety margin.

 The regulator is not otimized for more than 15-18 volts out so if you really want it to work good at more than 24 V out every single part must be examined.

 If you use the regulator with a preregulator you will only have 2-2.5 volts voltage drop over the main regulator, this may cause you trouble if you don't know the design.


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## Jazper

Quote:


  Originally Posted by *peranders* 
_I have just tested my Super Regulator with 25.30 V as output.

 Used parts, exactly as the basic design with the following changes:

 T4 D44H11
 T1, T6 BC560C
 IC2 LM329 (6.830 V)
 R3 2k2
 R8 2k7


 Load, current, min voltage in
 40 ohms, 625mA, 28.48V min
 30 ohms, 833mA, 28.80V min
 20 ohms, 1250mA, 29.42V min

 Note that min voltage in is really min voltage so if you have ripple you must add it. If you don't are able to verify how much ripple you have got you must have some safety margin.

 The regulator is not otimized for more than 15-18 volts out so if you really want it to work good at more than 24 V out every single part must be examined.

 If you use the regulator with a preregulator you will only have 2-2.5 volts voltage drop over the main regulator, this may cause you trouble if you don't know the design._

 

Right, well if I'm going to do that, then I'm going to need another board, which I can't really afford right at this moment (it's costing me a lot to put this together, and my poor bank account is feeling the hurt) so it's going to have to wait for a little while.


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## peranders

Since you for a while at least (still I'll hope) has got your Super Regulator working, what's your impressions so far?


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## Jazper

I was waiting on the case before I updated this thread, there has been setback after setback with that but finally I think it's going to be ready soon. A few things have happened since I last checked in. 

 First: 
  Quote:


  Originally Posted by *peranders* 
_Since you for a while at least (still I'll hope) has got your Super Regulator working, what's your impressions so far?_

 

Right.. The super regulator is still working so far, I found that the ths4601 opamp seems to be an improvement noise wise for the amp over the ad825. I also tried swapping in the ad797 but it didn't like the capacitive load even with a pair of diodes on the inputs.

 I have a ferrite bead over the power cables going out of the jung regulator, to the m3, and have increased capacitance after the regulator (so there's 3000uF straight after the jung, and 3000uF on the amp board) this seems to have helped everything, however bass slam is still marginally less than with the other "cheaper" power supply. 

 There is still some hiss at high volume which could be source related. I haven't had a whole lot of time to play with different sources yet.

 The output wires from the jung are very very sensitive to RF (especially AC hum), I might have to shield the AC wires. 

 The heatsinks on the jung regulator get pretty hot but the devices are within spec.


 Second:
 I've removed the C2 capacitors on the m3, and stuck with the ths4631 opamp. Removing the capacitors has seemed to make a very large difference in soundstage, vastly opening it up. Detail has also improved with the ths chips which before seemed very compressed and a bit grainy - while this could be due to burn in, I think it's more an effect of the caps. 



 I've biased the mosfets to 125mA and am running 25v through the m3. While I have been tempted to increase this I haven't needed to so there hasn't been any motivation to do so. If it ain't broke, don't fix it.

 I've found a slight anomaly with the AD8610 opamps, when driven hard (over half volume/gain 11) the treble becomes uncontrolled and peaky, but lower down it is fine. Covenant found the same problem with his mint (ad8620) so I'm guessing it is something to do with having them buffered or perhaps class A bias. 

 The case for the M3 is due tomorrow night.. I'm going to burn the midnight oil to try and get the amp ready for the meet in sydney on the weekend. Case pictures and final pictures will be forthcoming...

 Dakiller heard the amp on the weekend and his first remark was "very very detailed" - so I must have done something right. I've compared to his ppa (which also uses a protoboarded jung and has opa627 opamps) and I prefer the M3 by a large margin.

 I have another transformer coming from digikey, one that isn't so big, but I doubt it will be here in time for the meet. 


 that is all for now... here's a pic of the amp as it is, with the exception that the opamps have been changed to the ths4631s, and the opamp on the jung is now a ths4601:







 Jaz out (note more up to date pictures are coming..)


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## peranders

I think quite many of your problems are related to how you have built and also tested the M3. The M3 has a "virtual ground" and might be sensistive against bad wiring.

 It is also recommend NOT to have those huge caps together with a super regulator. The regulator is a wideband device and should not work together with thousand of uF.


----------



## Jazper

Quote:


  Originally Posted by *peranders* 
_It is also recommend NOT to have those huge caps together with a super regulator. The regulator is a wideband device and should not work together with thousand of uF._

 

There is very little difference in sound except slightly more bass slam, I don't see any reason not to


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## peranders

Quote:


  Originally Posted by *Jazper* 
_...I don't see any reason not to_

 

The reason to use a super regulator is that you want a low noise, low output impedance and most important for you a high speed regulator. If you add too much capacitance you will get worse step response and possible also stablity problems. It's not enough only to have "bass slam" as the only parameter.


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## Jazper

Quote:


  Originally Posted by *peranders* 
_The reason to use a super regulator is that you want a low noise, low output impedance and most important for you a high speed regulator. If you add too much capacitance you will get worse step response and possible also stablity problems. It's not enough only to have "bass slam" as the only parameter._

 

Remember also that with an amplifier you want very quick on demand power. Voltage stability has been fine so far. Within 5mV on average. Further, the caps I'm using are premium, low esr caps anyhow


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## peranders

Qiuck on demand power? Haven't you missed something, M3 is a class A amp with constant power demand, right?


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