# The SOHA II Tube Thread



## bmwpowere36m3

In the spirit of previous tube threads I'm starting this one for the SOHA II hybrid amplifier. I know it's a little early (prototypers just finished off their builds), but I'd like to get this started for interested users. The amplifier is based on the 12AU7 family of tubes and many others that have similar pinouts and electrical specs (ECC82, 5814, 5963, 12AT7, ECC81, 6DJ8, ECC88, 6922, E88CC, 8416, etc...). 

 So if users could list their experiances with all tubes they have used, a favorite/s and some description of their tone.


----------



## holland

used the following.

 mullard 12at7
 eh 12au7
 rca 5963
 eh 6922

 favorite eh 12au7

 rca 5963 a bit too lean
 eh 6922 very nice, but not as full as the eh 12au7
 mullard 12at7, too warm, bloated bottom end.
 eh 12au7 nice well rounded sound, aggressive, yet behaved. works great with my choice of music, primarily death and black metal.

 need to try 8416, always forget to buy some.


----------



## runeight

I have tried:

 Ei Elite 12au7
 EH 12au7
 Amperex 8416
 Brimar ECC82
 GE 6680
 JAN 6189
 RCA 5963
 RCA 6DJ8
 JJ 6922
 Amperex 6DJ8

 The Brimar is too shrill. The 8416, 6dj8, and 6922 are very mellow. The rest are in between and your choice would depend on what you like to hear. My favorite of the 12au7 family is the RCA 5963. For me it has the best and clearest sound with perfect highs.

 It is also fair to say that many of the 12au7 variations have not been broken in much. Everything could change if each set were run for 50 hours and then tested for SQ.


----------



## V-DiV

It might be useful to those building/balancing their system to know what headphones you used to gather these impressions since a pair of tubes could sound good with one set of cans but be a poor match for the sound signature of another.


----------



## holland

HD650, DT990. 

 Edit: Switched to using the Amperex 8416 now than the EH 12AU7. It has a bit more low end extension and softer upper end. Upper end variance is not that big, IMO. Still crisp, but not as forward.


----------



## Hayduke

The SOHA II will be my next amp project 
	

	
	
		
		

		
			





 In addition to which phones you're using, posting what music you listen to mostly will also help (like Holland did).

 I'm going to begin ordering parts sometime this weekend. I want to finish studying the build a bit first. I'll likely stick mostly to the 7007b BOM, but there are a few deviations I'm planning 
	

	
	
		
		

		
		
	


	




 This thread is going to be great for helping me pick a few tubes to start with.


----------



## wolf18t

Interesting thread. Still waiting for my SOHA II kit to arrive but in the meantime I ordered NOS Sylvania 5814A and Amperex Orange Globe 6DJ8 for tube rolling. 







 I'll let everyone know how they sound with my RS-1 and DT-880 in a few weeks if the build goes well.


----------



## holland

The Amperex 8416 is currently my favorite and I'm trying out the Amperex 6189 (Orange Globe). I'm still not quite sure what to make of the Amperex 6189.

 BTW, in case people aren't aware. In addition to rolling the tubes you can roll the output transistors. I was using the 2SC3421 but switched back to the BD137. The 2SC3421 makes some tubes sound too shrill. It really didn't go well with the 5963, for instance. The BD137 (stock is BD139) adds more warmth, and is less pronounced in the highs. The 5963 works better with that, though still not quite my favorite as it lacks punch.


----------



## KWS

SOHA II will also be my next amp project and i have read through the details of it.
 And most importantly,i can use one of my tubes collection,ie my TELEFUNKEN ECC82 12AU7 in this project.Of coz,i would let everyone know how they sound.


----------



## wolf18t

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_BTW, in case people aren't aware. In addition to rolling the tubes you can roll the output transistors. I was using the 2SC3421 but switched back to the BD137. The 2SC3421 makes some tubes sound too shrill. It really didn't go well with the 5963, for instance. The BD137 (stock is BD139) adds more warmth, and is less pronounced in the highs. The 5963 works better with that, though still not quite my favorite as it lacks punch._

 

I will use 2SC3422 in mine. Wish they will not sound as shrill as 2SC3421.


----------



## holland

I don't have the 2SC3422. I've been meaning to buy 50 or so for various projects, but it's a bit expensive. I don't think they will sound thin. I pulled the 2SC3421 from my Dynahi, as other than BDs those are all I've got.

 I believe some of the prototypers are using the 2SC3422. Ferrari definitely.


----------



## Ferrari

Quote:


  Originally Posted by *wolf18t* /img/forum/go_quote.gif 
_I will use 2SC3422 in mine. Wish they will not sound as shrill as 2SC3421._

 

I have used Toshiba 2SC3422 in the amp I built for my GF. I would call it neutral, fast sounding, with slamming bass and slightly on the warm side.

 This is in combination with Teflon interstage coupling caps and 6N1P-EB tubes in the front end.


----------



## wolf18t

Quote:


  Originally Posted by *Ferrari* /img/forum/go_quote.gif 
_I have used Toshiba 2SC3422 in the amp I built for my GF. I would call it neutral, fast sounding, with slamming bass and slightly on the warm side.

 This is in combination with Teflon interstage coupling caps and 6N1P-EB tubes in the front end. 
	

	
	
		
		

		
		
	


	


_

 

Thanks Ferrari. This is quite the sound signature I'm after to complement my slightly thin and forward upper mids/highs RS-1. The coupling caps should be the Mundorf M-CAP Supreme (not the silver oil series, I'm not that rich 
	

	
	
		
		

		
		
	


	




). 

 I have some high expectation from the Orange Globe. Read some good things about them. On the paper I think this Grado/2SC3422/Orange Globe combo should defenitly rocks with some good prog/classic rock material.


----------



## bmwpowere36m3

I've used:

 * Electro-Harmonix 12AU7's

 Listened with Senn HD580's and to music ranging from Pink Floyd, Led Zeppelin to Metallica, Alice in Chains, In Flames, AC/DC, to some classical. The EH tubes at first were a little harsh and very in your face, forward soundstage. As they burned in they've settled back, but still have a forward presentation. They have clear, defined highs, good midrange punch, and bass detail. I'd say the only thing they lack is maybe some more bass slam and midrange bloom, however like Holland has mentioned they sound wonderful paired with "Metal".

 All the music I've listened to sounds good and much more detailed than any other amp I've had thus far... when I start rolling tubes I'll be looking for something with a "warmer" sound (for Floyd, Classical, etc..), as the EH's are fairly neutral compared to my "SS" Hybrid which was very "tubey" sounding and a little overly warm.


----------



## Hayduke

I realize I'm a newb, but I'll ask anyway 
	

	
	
		
		

		
		
	


	




 How do you find suitable tubes? When I look at vendor's listings, there are thousands of tubes! I can find 12AU7 easy enough, but how do I find 6N1P-EB or RCA 5963 etc?

 When I am looking at the tube vendor listing, can a 12au be any of these? The place I got my 19J6s from has 2 listings, 12AU7/A and 12AU7A RCA. I was gonna order some part tonight, but I might hold off until I'm sure about what I want/need. I might just call them on Monday as well.


----------



## holland

buy em all!


----------



## holland

Amperex 6189. Big fat bass. Somewhat weird mids. Slightly boosted in some areas and slightly recessed in others. I haven't spent enough time with it, but I'm not sure I will. Most of my listening is with headphones that are fun (DT990, K240 Sextett) as the first tier. This pushes it too far for me. It might be good for something like the K701 (at least to me).


----------



## Hayduke

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_buy em all!_

 

Who will pay for them all? 
	

	
	
		
		

		
			





 Unfortunately, I'm starting to have those thoughts knowing that tubes are non-renewable resource 
	

	
	
		
		

		
		
	


	




 I'm just wondering if there are cross reference charts anywhere that show tubes are equivalents. I realize that any with the same pin layout, and heater power specs that are close, will work, but short of trying to find data sheets on every tube listed on the vendor's site, I'm not sure where to start. Well that's not entirely true, I am starting on this thread


----------



## holland

^^

 Get a job! 

 There's not really a cross-reference that I know of, though this might help https://www.tubeworld.com/12au7.htm. All the tubes being mentioned are 12AU7 family. 5963, 5814, 6189, 12AU7, 7730, 7316, 6680, ECC802. They vary slightly, but I don't know all of it offhand. I know the 5963 has lower plate voltage max, and is a computer tube. 5814 and 6189 are lower noise military tubes. 8416 is not a 12AU7 but a 12.6V version of the 6922. My favorite so far.

 The SOHA II can also use 6.3V heater tubes like the 6922 and 6DJ8. The russian tubes are a different beast. I have those, but haven't upgraded my transformer yet. I think I'll save those for my Bijou.

 Rolling tubes is an interesting thing, but I think it's coming to the end of the road for me and I'm getting bored of it. I have a couple more orders arriving soon, and then it's the end of the SOHA II era for me.

 BTW, I put back the RCA 5963 and I'm giving it a good whirl again with my Sextett. It's a remarkable tube. Quite Hi-Fi, IMO. The articulation and detail and separation is a definite stand out . I just wish it had more bass. Overall, I think they still don't have the balance I am looking for. I will try these again with the HD650. I think these might be a good complement for them (with the BD137 or BD139 output transistors not with the other set I tried). I'll try them with the HD650 in a few days.


----------



## Hayduke

OMG Holland! 
	

	
	
		
		

		
		
	


	




 I was hoping those prices were in some currency other then US dollars 
	

	
	
		
		

		
		
	


	




 I'd love to buy them all but there are some in there that are ~$1000 a pair! This company obviously knows a lot about tubes and has provided excellent info about the tubes, but they may to be too expensive for me. I'll have to study it a bit more. At least I have some model #s to look for.

 Thanks for the link.


----------



## wolf18t

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_The SOHA II can also use 6.3V heater tubes like the 6922 and 6DJ8. The russian tubes are a different beast. I have those, but haven't upgraded my transformer yet. I think I'll save those for my Bijou._

 

Holland, what russian tubes are you refering to? Do they need a higher heather current?


  Quote:


  Originally Posted by *Hayduke* /img/forum/go_quote.gif 
_I was hoping those prices were in some currency other then US dollars 
	

	
	
		
		

		
		
	


	




 I'd love to buy them all but there are some in there that are ~$1000 a pair!_

 

I'm a tube newbie too but I think those tubes now belong more to collectors (and investors) than audiophile. They might sound very good but not worth the price asked...


----------



## holland

Hayduke, you don't need to buy the expensive tubes. I don't.

 wolf18t, 6N1P-EB. Yes, higher heater current.


----------



## mrarroyo

Here are the specs on the 6N1P tubes: 6N1P, 6N1PVI, 6N1PEV (6H1n, 6H1nBN, 6H1nEB)


----------



## Hayduke

So let's say I wanted to order some tubes (and likely sockets) from Audio Tubes - Vacuum Tubes - ESRC Vacuum Tubes

 A couple that seem to get favorable reviews are 5963 and 6922. How are those listed in their catalog? Holland likes 12AU7's, but how do I know the brand? ESRC1 seems to offer RCA brand 12AU7s, should I get a set of those and the others to compare?

 I'm willing to spend a little money, but I'm hoping to keep it under $100 for tubes.


----------



## holland

I think you'll have to call them and find out.


----------



## Alcaudon

Quote:


  Originally Posted by *Hayduke* /img/forum/go_quote.gif 
_I'm just wondering if there are cross reference charts anywhere that show tubes are equivalents. I realize that any with the same pin layout, and heater power specs that are close, will work, but short of trying to find data sheets on every tube listed on the vendor's site, I'm not sure where to start. Well that's not entirely true, I am starting on this thread 
	

	
	
		
		

		
		
	


	


_

 

Hayduke, I use this site: TDSL Tube search it lists equivalents and links to other sites with more information.

 You can even download a software (for free) that does exactly the same, but you don't need to have an internet connection 
	

	
	
		
		

		
		
	


	




.
TDSL PE

 Hope it helps!!!


----------



## lacrossebowe8

Nice site. I just got some tubes:

 12AT7WC JAN Philips NOS-12AT7WC 2.0 $9.95 0 
 6189 / 12AU7WA NOS-6189 2.0 $11.95 0 

 One of the 12at7's is defective and the 6189's have such a high noise floor I won't use them, at least not for my grado's. 

 Anyone have some suggestions for a quiet tube?


----------



## Hayduke

Quote:


  Originally Posted by *Alcaudon* /img/forum/go_quote.gif 
_Hayduke, I use this site: TDSL Tube search it lists equivalents and links to other sites with more information.

 You can even download a software (for free) that does exactly the same, but you don't need to have an internet connection 
	

	
	
		
		

		
		
	


	




.
TDSL PE

 Hope it helps!!!_

 

Awesome! thanks 
	

	
	
		
		

		
		
	


	



 I ended up ordering 6 pairs of tubes 
	

	
	
		
		

		
		
	


	



 So far I've only listened to 2 types for more then 2 minutes. Mostly the 6DJ8s. I really love the sound, but I'm planning to try them all. I told myself I'd swap every week or so, but it's been more then that already. Too busy enjoying the music. Since the most popular here has been the 6189, I've been saving them for last, but I think they will be next


----------



## regal

Has anyone compared the 6N1P's to the 8416's? Trying to decide if a new transformer is worth it.


----------



## regal

Does JJ 12AU7 = EH 12AU7, same company ?


----------



## TimJo

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Does JJ 12AU7 = EH 12AU7, same company ?_

 

I don't think so. JJ is the new name for Tesla, whereas EH is Elctro-Harmonix. Two different manufactures as far as I know...


----------



## regal

I finished the amp today, started with RCA 5963's. I wasn't that impressed, sounded like a Millet Hybrid , some break-up distortion on complex loud passages. I turned up the tail current to 2.5 ma per tube and installed the NOS 8416's. Completely different amp, beautiful full rich sound with the detail to convey the ambience of the recording. I am very impressed with these tubes, it is cool to be able to own a true New Old Stock amperex 6(12)DJ8 for $50 a pair. I wish I had bought a dozen of these when they were selling for $10 a piece.


----------



## TimJo

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I wish I had bought a dozen of these when they were selling for $10 a piece._

 

You and me both... It has been my standby for awhile in the CTH. I guess Amperex was the only manufacturer of these, and were made specifically for Tektronix scopes. The gentleman I bought mine from (who is certainly an expert) said that 8416 is also one of the only tube designations that was never officially registered, and has yet to come across a datasheet for it.

 Sad story - A few weeks back, when crossing the room, my foot snagged my headphone cable and the CTH went flying - landing upside down - snapping the glass on one of these.


----------



## wolf18t

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I finished the amp today, started with RCA 5963's. I wasn't that impressed, sounded like a Millet Hybrid , some break-up distortion on complex loud passages. I turned up the tail current to 2.5 ma per tube and installed the NOS 8416's. Completely different amp, beautiful full rich sound with the detail to convey the ambience of the recording. I am very impressed with these tubes, it is cool to be able to own a true New Old Stock amperex 6(12)DJ8 for $50 a pair. I wish I had bought a dozen of these when they were selling for $10 a piece._

 

Actually, with all my headphones I've never been impressed by my Phillips 5963s. My favs are the Amperex 8416 with PS-1000 and Amperex Orange globe 6DJ8 with RS-1. I suppose 5963s sound better with Senns 6x0.


----------



## regal

I ordered some Mullard 12AU7's, has anyone tried them?


----------



## jjazzyj

I just recently got some 1955 CBS Hytron 5814A Black Plate Square Getter. Wow, a gigantic improvement over my late 60's Sylvania 5814A. Where the Sylvania were almost harsh sounding in the midrange and veiled in the high end, the Hytron's are smooth throughout and crisp in the high-end. Deeper soundstage as well. I've been listening to these for about 4 hours straight now and I never get tired of these. I'll be sad when they go.


----------



## TimJo

I have some Hytron tubes as well, although not 5814's, and they are very high quality indeed. Hard to find I'd say, but really nice sound.


----------



## TimJo

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I am very impressed with these tubes, it is cool to be able to own a true New Old Stock amperex 8416's._

 

I was able to find another pair of these last week. 
	

	
	
		
		

		
		
	


	




 These ones came in Tektronix boxes - p/n 154-0413-00. They must have been replacement tubes for whatever scopes these where used in at the time.


----------



## regal

The Mullard Blackburn 12AU7's sound marvelous, at least as good as the 8416's maybe better. Huge improvement over the RCA 5963's.


----------



## TimJo

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_The Mullard Blackburn 12AU7's sound marvelous, at least as good as the 8416's maybe better. Huge improvement over the RCA 5963's._

 

What time period are they from? 

 Have you ever watched that documentary filmed at the factory? Well, I guess it was more of a company informational film, but it is quite fascinating to watch what went in to building those tubes.


----------



## regal

Quote:


  Originally Posted by *TimJo* /img/forum/go_quote.gif 
_What time period are they from? 

 Have you ever watched that documentary filmed at the factory? Well, I guess it was more of a company informational film, but it is quite fascinating to watch what went in to building those tubes._

 

top O getters. Lastly they have Gf2 B 4H1 and Gf2 B3A4 factory/date codes, meaning they were made in Mullard's Blackburn, Lancashire plant.


----------



## nattonrice

:'( such lovely tubes~

 I was just going to grab some EH 12au7's...


----------



## regal

I compared the Amperex 8416's to the Mullard 12AU7's. The 8416's have a smoother thicker midrange while the Mullards excell in having more bass. I'm a guitar listening freak so I'm sticking with the 8416's.

 On another note this SOHA II is the first tube amp that has me completely impressed by Grados, never liked them till now, the Senns and AKG's are gathering dust after building this amp.


----------



## dBel84

lol , nothing smooths out a grado except for the original RS1's 
	

	
	
		
		

		
		
	


	




 you should try get your hands on some 6680's - I have some british made rebranded tubes which have great synergy with this amp. I still like the 8416 too but these have been getting more play ( actually the soha ii has been getting more play since my other amp is out on loan ) I forget just how well this amp performs overall. 

 ..dB


----------



## regal

Thanks will try the 6680's. I'm nuts about this amp + the new RS2's, great combo if you like classic rock guitar.


----------



## TimJo

Well, I see I need to find some 6680's. Thanks for the tip. 
	

	
	
		
		

		
			





 I've never been a fan of Grados (other than their phono carts) but maybe I need to try out the RS2's being that I'm a guitar freak as well. You never know...


----------



## bmwpowere36m3

Has anyone tried the Russian 6N1P tubes? So far I've used EH 12AU7 and HP 6DJ8 (by Amperex).


----------



## wolf18t

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_On another note this SOHA II is the first tube amp that has me completely impressed by Grados, never liked them till now, the Senns and AKG's are gathering dust after building this amp._

 

Finally I'm not alone using Grados with the SOHA II! In fact I prefer my SOHA II over my B22 with both RS-1 and PS-1000. 

 Try to get some Holland made 6DJ8 Orange Globes. Soundwise similar to 8416 but a bit smoother, they are less focused but they have larger images (intruments and singer voice is larger) and offer a more enveloping sound. I prefer them with the RS-1 than 8416. And yes, mids are as good as 8416 if not slightly better.


----------



## regal

Quote:


  Originally Posted by *wolf18t* /img/forum/go_quote.gif 
_Finally I'm not alone using Grados with the SOHA II! In fact I prefer my SOHA II over my B22 with both RS-1 and PS-1000. 

 Try to get some Holland made 6DJ8 Orange Globes. Soundwise similar to 8416 but a bit smoother, they are less focused but they have larger images (intruments and singer voice is larger) and offer a more enveloping sound. I prefer them with the RS-1 than 8416. And yes, mids are as good as 8416 if not slightly better._

 

I think I have a pair of amperex orange globes 6DJ8, will give this a try.


----------



## regal

Here's how to get the most of your tubes on the SOHA II. The issue I was hearing on some of the 12AU7s and 6DJ8's was a slight weakness or thinness. So here is how you can safely get more current thru the tube:

 1. Set B+ to 85V
 2. Add another 18k ohm resistor on top (parallel) of R4L&R (makes it 9k ohm)
 3. Add another 200 ohm resistor on top (parallel) of R6L&R (makes it 100 ohm)

 Adjust P1L&R to give .550 V across R6L&R

 Check to make sure you have at least a 19V drop across the top CCS (adjust P1 until you do)

 This gives 2.75 mA thru each tube section.

 Now the Mullard 12AU7's has pulled ahead of the 8416's. All the tubes I have been working with are sounding better.

 I think the original design of 1 mA per tube section is too low and a remnant of the old (pre TL783) PS design. The amp is competing with what I breifly remember my Stacker II sounding like. The biggest improvement is in bass definition (i.e. telling the difference between the bass drum and the bass guitar.)

 .


----------



## tacitapproval

I tried this mod and it does sound good. I will have to do more extensive listening to pick out the changes.

 Is there a downside to this? Am I stressing the tubes or other parts? I do have almost a 30v drop, is this too much?


----------



## holland

I run @ 5mA per triode. There are no downsides that I can see. The only thing you need to worry about is the voltage drop across the cap multiplier. It is relative to current (the more current, the larger the drop). If you have the proto board with 3 cap multipliers on the B+ rail you may have to remove some.

 The higher current then led to a higher voltage B+ mod.


----------



## regal

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I tried this mod and it does sound good. I will have to do more extensive listening to pick out the changes.

 Is there a downside to this? Am I stressing the tubes or other parts? I do have almost a 30v drop, is this too much?_

 


 5ma is still on the low side, so you aren't stressing the tube at all. If you raise B+ and change R4 to 9k you shouldn't get a 30V voltage drop across the CCS but it shouldn't hurt.


----------



## tacitapproval

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_5ma is still on the low side, so you aren't stressing the tube at all. If you raise B+ and change R4 to 9k you shouldn't get a 30V voltage drop across the CCS but it shouldn't hurt._

 

I did both of those steps and r6 is 100--not sure why I get that much of a voltage drop.


----------



## regal

its just your tube curves, won't hurt anything. Different tubes will give a different plate voltage but the current will stay the same.


----------



## bmwpowere36m3

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_I run @ 5mA per triode. There are no downsides that I can see. The only thing you need to worry about is the voltage drop across the cap multiplier. It is relative to current (the more current, the larger the drop). If you have the proto board with 3 cap multipliers on the B+ rail you may have to remove some.

 The higher current then led to a higher voltage B+ mod. 
	

	
	
		
		

		
		
	


	


_

 

So a 10 mA tail current, correct? That would require a ~3.6k R4, correct? Along with ~ 66R for R6 & P1, so you could just jump R6 with a lead and just use the 200R trimpot.


----------



## regal

Before I went up to 10mamp I would check the heat dissapation capabilities of the CCS transistors and the HV regulators. May be risky.


----------



## regal

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_
 The higher current then led to a higher voltage B+ mod. 
	

	
	
		
		

		
		
	


	


_

 

You just have to rub that in 
	

	
	
		
		

		
		
	


	





 You just wait till my Stacker II works with OCTAL tubes


----------



## tacitapproval

This sounds really good. I am listening to Bitches Brew now and wow, the bass is thumping. 
	

	
	
		
		

		
		
	


	




 With the 6n23, I get 84v at B+ and 53v at TP. With 5814, I get 84v and 56v, respecitvely. I did use a 22k resistor at r4 (I didn't have 18k), so I get 9.8k--I think I have some 16k's, so I could switch to that if it would be better. R6 is 110ohms (I only had 220s), with 550mV across it. 

 By the way, this is the production board, not the proto, so I believe the HV changes were already made?

 edit: 6211 gives a 20v drop--83v and 63v. Interesting.


----------



## regal

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_This sounds really good. I am listening to Bitches Brew now and wow, the bass is thumping. 
	

	
	
		
		

		
		
	


	




 ._

 



 Yea it really helps the bass.


----------



## kostalex

Please, recommend some tubes for SOHA II > W5000 combo. Music are blues, jazz, jazz vocal.


----------



## regal

Quote:


  Originally Posted by *kostalex* /img/forum/go_quote.gif 
_Please, recommend some tubes for SOHA II > W5000 combo. Music are blues, jazz, jazz vocal._

 

The best tubes so far I've found are Amperex 12AU7's.


----------



## sachu

As Don was mulling, can someone try running 6Cg7s in them..if it works..a pair of cleartops should do brilliantly in this powerhouse of an amp.
 90 volts on the plates is plenty..jsut make sure your heater can deliver atleast 700mA at 12.6 volts or 1.5 A at 6.3 volts if you run them in parallel.


----------



## dBel84

Well I did more than mull and I have to say that the 6FQ7 has now surpassed all tubes in this amp - I imagine with a little tweaking to get more current on the cathode, this would be even better. It is still not up to the level of my former amp but it is almost there. 

 an analogy might help - SOHA II with 6FQ7 = High Def iMax imaging, former amp with 6FQ7 = iMax 3D 

 I can now enjoy my music once again..dB


----------



## regal

Quote:


  Originally Posted by *dBel84* /img/forum/go_quote.gif 
_Well I did more than mull and I have to say that the 6FQ7 has now surpassed all tubes in this amp - I imagine with a little tweaking to get more current on the cathode, this would be even better. It is still not up to the level of my former amp but it is almost there. 

 an analogy might help - SOHA II with 6FQ7 = High Def iMax imaging, former amp with 6FQ7 = iMax 3D 

 I can now enjoy my music once again..dB_

 

Does the stock heater supply handle this much current the 6FQ7 requires?


----------



## eruditass

I have tubes that say RCA 5963 on the box, but have green writing on the tube itself that say Sylvania 5963. Any experiences / comparisons with Sylvana 5963? Also, I'm interested in the 6680 and 8416 if anyone has more specific comparisons.

 And for tubes with a higher heater current, how much larger heatsinks are required? Any recommend low profile ones? Maybe that tail current mod will make me happy enough.


----------



## dBel84

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Does the stock heater supply handle this much current the 6FQ7 requires?_

 

The reg is a 1.5A regulator , mine has a larger heatsink but I don't think this will make much difference. In normal operation, you are running most tubes at 12.6V in parallel - ie 12.6V with 300mA + 300mA = 12.6V and 600mA. The 6.3V tubes run in series and thus the voltage is additive but the current remains the same - still 600mA. 

 That is if I am thinking about this logically..dB

 @DoomzDayz : the 6680 is the closest to the 6FQ7 of the tubes that I have tried - Tungsol 12AU7, philips 5814, amperex 8416, sylvania 5963


----------



## Alcaudon

Maybe a bit offtopic, I'm sorry, but since you are already discussing about current issues here... 
	

	
	
		
		

		
			





 dBel, do you know how much is the total current draw from the entire amp? I'm going to add in the same case as the SohaII an alien DAC that I have laying around and a TPA Darwin selector. 

 The Darwin needs a 5V 60 mA ps, and I was planning to use one of the 3 leds for this (adding a regulator, or maybe a σ25), am I safe using the bom's 1A transformer or should I go for something beefier?

 Thanks!!!


----------



## regal

Quote:


  Originally Posted by *dBel84* /img/forum/go_quote.gif 
_The reg is a 1.5A regulator , mine has a larger heatsink but I don't think this will make much difference. In normal operation, you are running most tubes at 12.6V in parallel - ie 12.6V with 300mA + 300mA = 12.6V and 600mA. The 6.3V tubes run in series and thus the voltage is additive but the current remains the same - still 600mA. 

 That is if I am thinking about this logically..dB

 @DoomzDayz : the 6680 is the closest to the 6FQ7 of the tubes that I have tried - Tungsol 12AU7, philips 5814, amperex 8416, sylvania 5963_

 

I don't know, the way I read Runelights webpage he is saying max 300 mA 6.3 V tubes. pS give the Amperex 12AU7 at try they are incredible.


----------



## runeight

Almost. 
	

	
	
		
		

		
		
	


	




 Most 12.6V tubes that work in this amp are 150mA. Two in parallel is 300mA.

 Most 6.3V tubes will be 300mA. Two in series will be 300mA.

 Thus the design center for the heater supply is 12.6V/300mA. This handles most of the trubes.

 However, 12bh7 for example is 300mA. Its draw in parallel will be 600mA.

 The regulator can manage most of this range. However, R3P is there to drop some voltage and burn some power so that the reg doesn't have to do it. If the current draw gets too high the drop across R3P will cause the regulator to de-regulate. Hence, if your draws are higher than 300mA or so you should remove R3P.

 But, then the reg will burn much hotter hence the need for off board heatsinks.

 I don't know if this answers any of the questions, but hopefully it helps somehow.


----------



## dBel84

much appreciated, my math was correct just the current draw of a regular 12.6V tube was off. 

 My amp does not have R3P and has beefier heatsinks, thus the ability to use these tubes in my amp..dB


----------



## regal

Quote:


  Originally Posted by *dBel84* /img/forum/go_quote.gif 
_much appreciated, my math was correct just the current draw of a regular 12.6V tube was off. 

 My amp does not have R3P and has beefier heatsinks, thus the ability to use these tubes in my amp..dB_

 

Does this negate your ability to run 150 mA 12.6V tubes like the 12AU7's?


----------



## runeight

With the larger heatsinks you can run 150mA tubes in parallel without R3P.


----------



## dBel84

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Does this negate your ability to run 150 mA 12.6V tubes like the 12AU7's?_

 

No I was thinking they ran higher currents - ie 300mA not 150mA so I had calculated that in parallel they would use 600mA routinely as opposed the the 300mA that they do. Thus my comment that the 6FQ7 would add no greater load in series while in fact they double the load - and I am sure that statement is more confusing than just thinking about it all 
	

	
	
		
		

		
		
	


	




 . 

 I did some further testing and although the heatsinks can tolerate the 6FQ7, the chassis gets very toasty - too much so in fact . So good ventilation is also key for higher current demands. 


 and runeight addressed the heatsinking issue already.

 ..dB


----------



## regal

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Here's how to get the most of your tubes on the SOHA II. The issue I was hearing on some of the 12AU7s and 6DJ8's was a slight weakness or thinness. So here is how you can safely get more current thru the tube:

 1. Set B+ to 85V
 2. Add another 18k ohm resistor on top (parallel) of R4L&R (makes it 9k ohm)
 3. Add another 200 ohm resistor on top (parallel) of R6L&R (makes it 100 ohm)

 Adjust P1L&R to give .550 V across R6L&R

 Check to make sure you have at least a 19V drop across the top CCS (adjust P1 until you do)

 This gives 2.75 mA thru each tube section.


 ._

 


 I found that some tubes pull down the CCS a little more than others and it causes the E12 to trip. I recommend setting B+ to 80V which cured this issue with this high current config.


----------



## jmf

Hi,

 I just launched the amp. I must say that I found the amp too lean with the provided Sylvania 5369. I was a bit dispointed.

 I had found in an old electronic lab a pair of RCA 6922 (golden pin). Just changed the jumpers on the board and tried those lamps.

 => a completely different amp : more warm, more full, more flesh (but maybe the piano is still not OK...). Maybe less speed and not as good on strings.

 Is a so big difference between Sylvania 5363 and RCA 6922 normal ?

 Are my "feelings" in line with what one could normally wait from those lamps ?

 (I use SOHA II with K701 + Monica DAC (DIYParadise))

 Regards.

 JM.


----------



## regal

Quote:


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

 I just launched the amp. I must say that I found the amp too lean with the provided Sylvania 5369. I was a bit dispointed.

 I had found in an old electronic lab a pair of RCA 6922 (golden pin). Just changed the jumpers on the board and tried those lamps.

 => a completely different amp : more warm, more full, more flesh (but maybe the piano is still not OK...). Maybe less speed and not as good on strings.

 Is a so big difference between Sylvania 5363 and RCA 6922 normal ?

 Are my "feelings" in line with what one could normally wait from those lamps ?

 (I use SOHA II with K701 + Monica DAC (DIYParadise))

 Regards.

 JM._

 


 Try it with a real Amperex 6Dj8/6922 and the tail current mod I posted and it is a huge step up from the stock 5963 setup, talking a completely different amp.


----------



## jmf

I'll try to find Amperex tubes...

 In a fist time, I would have prefered not tomod the amp (aka add resistors...), but if it makes the difference .

 I also do not understand if it needs mods to try the 6FQ7 tubes...

 Regards.

 JM


----------



## jmf

Hi,

 One more question : what can be the max B+, tail current possible to experiment in a "plain vanilla" SOHA II : without resistor / heatsink / transfo mods ?

 I see that this "setpoint" is an important point, but I won't have time to source new components, get the board out of the box...

 Definitly, with 6922 and K701, I'm happy with voices, but not the Piano.

 Thank's a lot for all infos.

 Cheers.

 JM.


----------



## regal

Quote:


  Originally Posted by *jmf* /img/forum/go_quote.gif 
_I'll try to find Amperex tubes...

 In a fist time, I would have prefered not tomod the amp (aka add resistors...), but if it makes the difference .

 I also do not understand if it needs mods to try the 6FQ7 tubes...

 Regards.

 JM_

 

Yes 6FQ7 needs the heater mod. The piano will come alive with Holland 6922/6DJ8's.


----------



## darkhoek

I got a tip to try out the TESLA E88CC goldpin. They sound really magnificent. The Phillips SQ tubes sounded a bit lean IMO, but very smooth. The Teslas however has a poweful yet very defined and detailed low end, beautiful mids and a crystal high. At any price they are good, at their asking price they are an absolute steal. My Denon AH-D5000 Markl modded cans with the Jena ultrawire/Furutech upgrade sound abolutely etherical with the SOHA II w/Mundorf Supreme silver/oli caps and these wonderful Teslas.







 BTW, Tesla had two plants where these E88CCs were made, and the 32 plant is said to have by far the best quality.


----------



## regal

Quote:


  Originally Posted by *darkhoek* /img/forum/go_quote.gif 
_I got a tip to try out the TESLA E88CC goldpin. They sound really magnificent. The Phillips SQ tubes sounded a bit lean IMO, but very smooth. The Teslas however has a poweful yet very defined and detailed low end, beautiful mids and a crystal high. At any price they are good, at their asking price they are an absolute steal. My Denon AH-D5000 Markl modded cans with the Jena ultrawire/Furutech upgrade sound abolutely etherical with the SOHA II w/Mundorf Supreme silver/oli caps and these wonderful Teslas.






 BTW, Tesla had two plants where these E88CCs were made, and the 32 plant is said to have by far the best quality._

 


 I like the 1970's Tesla 6922's they do have good bass and are underrated, tubemonger.com is a good source for them. I didn't like my Phillips SQ 6922's and sold them they were deffinately lean, my favorite now is the 8416 Amperex tied with the Mullard 12AU7.

 Were you able to fit the Mundorf SIO caps in the standard Hammond enclosure?


----------



## darkhoek

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_I like the 1970's Tesla 6922's they do have good bass and are underrated, tubemonger.com is a good source for them. I didn't like my Phillips SQ 6922's and sold them they were deffinately lean, my favorite now is the 8416 Amperex tied with the Mullard 12AU7.

 Were you able to fit the Mundorf SIO caps in the standard Hammond enclosure?_

 

Well, kinda. To get proper cooling, I made a new lid from perforated aluminium, and raised the hight a tad towards the sides of the cabinet while I were at it, almost like fitting a turbo under the hood of a smallish car 
	

	
	
		
		

		
		
	


	




 BTW I am planning to do your high current MOD to the SOHA to see if even more good can be squeezed out of this little marvel of a head amp.


----------



## regal

Quote:


  Originally Posted by *darkhoek* /img/forum/go_quote.gif 
_Well, kinda. To get proper cooling, I made a new lid from perforated aluminium, and raised the hight a tad towards the sides of the cabinet while I were at it, almost like fitting a turbo under the hood of a smallish car 
	

	
	
		
		

		
		
	


	




 BTW I am planning to do your high current MOD to the SOHA to see if even more good can be squeezed out of this little marvel of a head amp._

 

Thanks, I have KY40s under my PCB in the standard enclosure but know that the Mundorf SIO would sound much better. I have a perforated top but can you share a picture? I think this is a super mod you have done.


----------



## darkhoek

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Thanks, I have KY40s under my PCB in the standard enclosure but know that the Mundorf SIO would sound much better. I have a perforated top but can you share a picture? I think this is a super mod you have done._

 

Here are some pictures. I have installed a switch on the back to be able to flip the heater voltage w/o opening the amp when rolling tubes. I have done the 600mA heater mod to be able to experiment with some of the russian tubes (6N1P). I also found out that when using my media player, a SONY NWZ-829, bypassing the Alps pot by installing a "direct-in" as you can see just to the left of the volume knob on the front, would do the sound more dynamic and airy. No use passing the signal through two attenuators.

 The lid is made from an old PC tower cabinet side panel. The metal is somewhat thinner than the original lid, and by adding the small ridge along the edge, I gain about 5mm inside, which is just enough to host the Mundorf barrels. The real problem is that the cap leads are to fat for the holes in the PCB, so I have silver soldered the cap directly to the tube socket and R15. 

 I am really intrigued by the SOHA II design, and I am thinking about buying a couple of blank SOHA II boards to build different versions. One all botique with tantalum/Holco resistors, Nichicon/ cerafine or other caps, silver wiring the signal path, teflon tube sockets, ladder type 24 step volume regulator with Holco/tantalum resistors, larger cabinet or alternatively separate power supply plus your tail current mod, and one standard "very safe" version with an inbuilt USB DAC for my work place.

Attachment 28081

Attachment 28082

Attachment 28083

Attachment 28084

Attachment 28085


----------



## regal

Thats amazing, how did you get that beautiful bend in the perforated aluminum? I need to try this.


----------



## darkhoek

Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_Thats amazing, how did you get that beautiful bend in the perforated aluminum? I need to try this._

 

Well, the 90 degree bend towards the front panel was already a bend in the PC cabinet panel,so I started from that and cut out a piece that was about 0,2" wider than the original top of the hammond case. Then I made a jig from two pieces of stiff plywood and mounted them together with a piece of the panel material inbetween them so that I got something like a vice. See cross section to the left. Then I could place the perforated metal sheet in the slot and by pressing as close to the vice as possible I got a nice controlled bend. By bending along the perforations I didn't have to use much force either, and got naturally straight bends.

Attachment 28086


----------



## regal

Fantastic job. May be beyond my skillset as chassis work isn't my forte' but I got to try with my other hybrid upgrading the coupling caps from Ky40s made a huge improvement.


 Has anyone tried rolling the output transistors? I've had real good luck with the 2SC 3421's from Beezar.com in other amps, think I might try them in the SOHAII.


----------



## TimJo

You really built a nice amp darkhoek. Nice work on the enclosure too. Very creative problem solving... 

 I hope you get the chance to build the other custom version, and if you do, be sure to take more pictures...


----------



## darkhoek

Thanks guys. I'll make sure to take pictures of the eventual SOHA II tour de Force, cost no object, hot shot sundance version build... or what ever...


----------



## Nevohteeb

Hello everyone,

 I finished my SOHA II amp two days ago, using them with a pair of 12at7 from Telefunken that I got for free at work and a Sennheiser HD535 that I own for 16 years now and still work perfectly. Nevertheless, I'm not really happy with those tubes, so I'm looking for another pair.

  Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_eh 12au7 nice well rounded sound, aggressive, yet behaved. works great with my choice of music, primarily death and black metal._

 

 Quote:


  Originally Posted by *bmwpowere36m3* /img/forum/go_quote.gif 
_I've used:

 * Electro-Harmonix 12AU7's

 Listened with Senn HD580's and to music ranging from Pink Floyd, Led Zeppelin to Metallica, Alice in Chains, In Flames, AC/DC, to some classical. The EH tubes at first were a little harsh and very in your face, forward soundstage. As they burned in they've settled back, but still have a forward presentation. They have clear, defined highs, good midrange punch, and bass detail. I'd say the only thing they lack is maybe some more bass slam and midrange bloom, however like Holland has mentioned they sound wonderful paired with "Metal"._

 

Metal (Death, Black, "extreme"), classical (operas and symphonies) and Pink Floyd are what I listen to the most. So, according to the comments above, I should try to find a pair of EH 12au7.

 There are some on ebay, for reasonable prices, but there are several versions : black box, gold box... Which ones would you recommend?

 Moreover, as I said, metal is not the only kind of music I listen to, so will those tubes match my other tastes?

 Thank you very much for you answers.


----------



## regal

There is a SOhaII tube rolling thread here, read it before jumping on the EH's.


----------



## Nevohteeb

Hello,

  Quote:


  Originally Posted by *regal* /img/forum/go_quote.gif 
_There is a SOhaII tube rolling thread here_

 

I read the 6 pages, and it seems that both Holland and bmwpowere36m3 enjoyed the EHs for metal music.

 Did I miss another rolling tube thread?


----------



## regal

Quote: 





nevohteeb said:


> Hello,
> 
> Code:
> 
> ...


 


 No I just wanted to make sure you knew about the thread to be an educated consumer   Actually thought I was posting on the SOHAII builders thread,  with the chaos of the format change I'm all confused.


----------



## Nevohteeb

Quote: 





regal said:


> No I just wanted to make sure you knew about the thread to be an educated consumer   Actually thought I was posting on the SOHAII builders thread,  with the chaos of the format change I'm all confused.


 

 No worry. 
  I always read as much thread as I can before I ask something. Here, I read two people saying that the EH 12au7 are good for Metal music, but I wanted to have a little more feedback.
   
  I bought a brand new pair of EH 12au7 for a very good price, so we'll see


----------



## huskydawg9

Luv it!  Wish I would have read this thread about the mod first though...it would have been a lot easier...


----------



## regal

Yea I think Alex didn't put it on his website because it can be more difficult to setup.  I recommend you plug in a space heater to the outlet you intent on using the SOHAII and checking mains AC voltage at that receptale,  to see if the voltage drops more than 10V's,   Some old houses and rural power company's have this problem and you fight E12 dropouts,  the cure is just to lower B+.  The mod is worth it IMO.
  
  Quote: 





huskydawg9 said:


> Luv it!  Wish I would have read this thread about the mod first though...it would have been a lot easier...


----------



## huskydawg9

Just upgraded the transformer and rolled in 6H30's.  SWEET!  Sure generates the heat though.  Had to improvise with additional heatsinks...


----------



## Navyblue

Quote: 





regal said:


> Here's how to get the most of your tubes on the SOHA II. The issue I was hearing on some of the 12AU7s and 6DJ8's was a slight weakness or thinness. So here is how you can safely get more current thru the tube:
> 
> 1. Set B+ to 85V
> 2. Add another 18k ohm resistor on top (parallel) of R4L&R (makes it 9k ohm)
> ...


 

 Can anyone tell me, if I just install half of the value for R4 and R6 right from the start, would 1/8W resistor be sufficient? Or would I need to for 1/4W? This would be a mild problem since the board is so cramped.
   
  Thanks.


----------

