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opinion of using a 6SN7 over a 12AU7 in an amp driver boards

I'm using a VTA ST70 amp that uses the 12AU7, but I'm actually using the 12BH7's in it's place. I have to say it is a stellar performing amp. It's crisp, articulate and bass can hold its own against any SS amp.

I just want to make this perfectly clear. This amp is an amazing performer. This all has to do with MY taste and nothing to do with the amp.

However ---- my taste leans more towards a romantic fuller midrange sound signature. I've tube rolled to the point were I know it's never going to be what I want.

I'm asking this as a last ditch attempt to warm up the midrange ONLY option. Knowing that the 6SN7 is basically an earlier version of the 12AU7, is there any chance this tube would present a more "romantic fuller midrange" sound in this amp????

I'm gonna be honest. I can get the same sound, and in many cases more pleasant sound. from my SS amps.

I've also considered reverting the driver board back to original and use my 7643 driver tubes.

You've tried all the 12AU7 iterations? If you have time to search and a bit of extra cash in the pocket... a couple of tube suggestions. Black plate CBS-Hytron 5814A and 7318. Those will warm the mids and keep the bass and top end. Need strong testing, quiet ones.



5814A CBS-Hytron.jpg
7318 CBS Hytron (small).jpg
 
You've tried all the 12AU7 iterations? If you have time to search and a bit of extra cash in the pocket... a couple of tube suggestions. Black plate CBS-Hytron 5814A and 7318. Those will warm the mids and keep the bass and top end. Need strong testing, quiet ones.



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View attachment 2092484

You mean the 7316? A wonderful tube, but soooooo expensive now, really almost prohibitive--and I'm not a cheapskate about good NOS tubes. Those black plate 5814s look nice, though!
 
You've tried all the 12AU7 iterations? If you have time to search and a bit of extra cash in the pocket... a couple of tube suggestions. Black plate CBS-Hytron 5814A and 7318. Need strong testing, quiet ones.
Thank you very much for the suggestion. I'm really trying to avoid having to use the "golden tube" type amps these days. I've tried about 15 different brands and variations of driver tubes in this amp. Again, it's my taste that's the problem and not the amp. I've found that tube rolling only changes "shades" of what I'm not preferring.
 
@airtime , If you can't kick back, enjoy the music and relax with this amp, you have others.

Maybe, this really is decision time, this time...Sell it and get another sweet sounding EL84 amp. Or, keep on enjoying the Sherwood 5000 and when you want to hear the sound of the equipment, plug in your ss amps...Listen to the music and enjoy....
 
You mean the 7316? A wonderful tube, but soooooo expensive now, really almost prohibitive--and I'm not a cheapskate about good NOS tubes. Those black plate 5814s look nice, though!

Both the 7316 and the 7318 are super long lasting mil spec/industrial grade tubes. The CBS-Hytron 7318 is one of the best duo-triode tubes I've heard, of any duo-triode types. Too bad they are so hard to find.

https://community.klipsch.com/index.php?/topic/163603-pair-cbs-7318s-very-rare/
 
I was working on an Ampeg guitar amp. V22, I think. Anyhow, Ampeg used all kinds of nice glass in their amps. But, often Ampeg amps used 12AU7 tubes as phase inverters. A tech told me about the CBS-Hytron 7318. Man, this tube transformed that amp! Midrange and bass is much better than the Sylvania 12AU7A which was in the amp. Super clean, not overly bright highs. So, bought several sleeves. This was in the early 1990s and no one ever heard of the 7318. Only the 7316 and 5814A, which as not as full sounding (IMHO).

A sleeve of five were like $50 NOS. Ppl were glad to get rid of them. Anyhow, the best has smoked inner glass and black sooty plates. Square getter rings. They last FOREVER. Built like those Bendix tubes. You plug them into any amp which is setup and maintained properly, and forget them. They will outlast you and your kids. They will prolly outlast the volume control knob. :D

7318_CBS2ss.jpg
 
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I've found that tube rolling only changes "shades" of what I'm not preferring.
Exactly.

Which is why I keep asking if you've tried using an EQ and suggesting that you try one if you haven't. I'm puzzled why you seem to be totally ignoring this suggestion.

If you use a quality EQ of some sort it WILL solve your problem. When the music was being recorded and mastered in the studio, that's what they used to adjust tonal balance. Why? Because it works.
 
I get the sense that his other amps have poor low and high end response, giving the impression of "fuller midrange." It's the only thing I can think of that would create that "sound of the amp".... he seems to have experienced and prefers. Or there is a genuine problem with the amp in question... not likely.
I doubt that's the case. He also owns a Sherwood S-5000 that was rebuilt by a highly qualified tech. I have Sherwoods too, including that same version (PP 6BQ5) of the S-5000 and I can assure you that it is not lacking in low or high end response.
 
I get the sense that his other amps have poor low and high end response, giving the impression of "fuller midrange.". Or there is a genuine problem with the amp in question... not likely.
My other amps are fine. You're making assumptions with no knowledge of what other gear and experience I have. Also the amp I AM talking about is working to spec and in perfect working order. The problem, and I'm going to say it yet AGAIN, is that the amps sound signature and my taste are not compatible.
 
Yep. and as you can see I was having a personal issue even back then. As the Honeymoon wore off the same personal issues became evident again. As I did mention, this is an excellent amp, but apparently not inline with my taste.
 
My other amps are fine. You're making assumptions with no knowledge of what other gear and experience I have. Also the amp I AM talking about is working to spec and in perfect working order. The problem, and I'm going to say it yet AGAIN, is that the amps sound signature and my taste are not compatible.
Yep. and as you can see I was having a personal issue even back then. As the Honeymoon wore off the same personal issues became evident again. As I did mention, this is an excellent amp, but apparently not inline with my taste.
I don't think you really want to solve the problem.

As someone who has been reading your posts about Dynaco amps for almost 20 years now, first on AA and now here, I've now come to the conclusion that you just need something to obsess over.

That explains why you seem determined to totally ignore the one measure that will solve the problem - using an EQ. If a minor adjustment solves the problem, you wouldn't have anything to obsess about. And where's the fun in that?

You've tried rolling the stock tube types so that obsession has been exhausted. So maybe switching to 6SN7s is the way to go. Think of all the variations of the 6SN7 that you'll be able to play with. And don't forget cables. Or have you been down that road?

Others may think that you're just looking for an excuse to get rid of it. And it certainly sounds like you might be leaning in that direction.

If that's the case, here's a post by someone who's done that and regretted it . . .

https://db.audioasylum.com/mhtml/m.html?forum=amp&n=215283&highlight=dynaco+airtime&r=&search_url=/cgi/search.mpl?searchtext=silicone&b=AND&topics_only=N&author=&forum=vinyl

:p
 
Hi... Just want to ad my thoughts...

I have about 30 years of tube experience in designing, building, tuning and repairing al kinds of tube amps...
There are many ways to make an amp sound the way it does...

And then even not every tube sounds the same... There are even brands who use that fact to sell different sounds...(Groove tubes)

Tip 1.
But Sometimes, as a amp user and music lover, you just need to step back... Give your head, and your ears a little holiday...
Do not listen to find that special sound, that sweet mids, or warm lows, or that kristal high...

Shut down that amp... Shutdown that Turntable....shutdown your ears... not for two minutes... but a week or even longer... Make sure you don't have a cold, or that problem in the back of your head...

Then.... al of a sudden when you have regaind your listning energie you suddenly hear things you missed...

For me this is often the case.... It helps to get a fresh set of ears every now and then.... A holiday from your music.... just try it.. you might be amazed...​

Tip 2.
Take a good look into your room ... what has changed... new carpet, new curtains, New painting on the wall? Gone from Single pane of glass to Double isolating glass? New door? It is winter in the world... maybe you burn a wood stove and have a stack of fire wood added to the room?
can it be that something is dampening that sweet mids your looking for? That new big thick sweater you wear?

Sometimes very basic thing can change the way "recieve" music...

Thats whats makes it so subjective...and also a nice hobby.​
 
I don't think you really want to solve the problem.

As someone who has been reading your posts about Dynaco amps for almost 20 years now, first on AA and now here, I've now come to the conclusion that you just need something to obsess over.

That explains why you seem determined to totally ignore the one measure that will solve the problem - using an EQ. If a minor adjustment solves the problem, you wouldn't have anything to obsess about. And where's the fun in that?

You've tried rolling the stock tube types so that obsession has been exhausted. So maybe switching to 6SN7s is the way to go. Think of all the variations of the 6SN7 that you'll be able to play with. And don't forget cables. Or have you been down that road?

Others may think that you're just looking for an excuse to get rid of it. And it certainly sounds like you might be leaning in that direction.

If that's the case, here's a post by someone who's done that and regretted it . . .

https://db.audioasylum.com/mhtml/m.html?forum=amp&n=215283&highlight=dynaco+airtime&r=&search_url=/cgi/search.mpl?searchtext=silicone&b=AND&topics_only=N&author=&forum=vinyl

:p

Tube and cap rolling is better than a lot of other obsessions? No? :D

counting_money.gif
 
This is a hobby. I'm not sure what other hobbies some of you have been involved in, but even at the "top end", being an audiophile is pretty low budget. I have friends that ride $10,000 bicycles. I'm shocked when I see people crying about what some of the NOS specialty tubes cost, go price a Leica camera lens or what auto collectors spend. How much are we even talking about for this 6SN7 kit he wants to try, a couple of hundred bucks? I honestly am having a blast rolling different driver tubes in my amp matching them to different source materials. There is something special to me not using tone controls but by getting the EQ using the sonics from different tubes. Just because someone doesn't want to use an EQ, is no different than someone choosing a tube amp, or in my other passion photography, shooting film over digital. And in photography I see people saying "Oh just shoot digital and you can adjust it to look just like film, well no you can't.

It's his money, if he wants to spend it rolling tubes, doing amp mods or whatever and it makes him happy, why do people care?
 
Anyone here try a Mullard or Brimar 6SN7GTY or CV1988 tube? I remember hearing these tubes in a phono pre-amp, of a friend, a long time ago. It was a silky smooth, quite natural sound. Was quite impressed. :)

mullard-cv1988-6sn7gty-7226-01.jpg
 
I would guess that the 6sn7 will not sound substantially different than the 12AU7 you have right now.
Reducing the amount of global feedback may be more likely to get you there. Reducing the feedback can be done with a few cents worth of resistors, versus totally rebuilding the driver stage to run different tubes, which is likely to cost greater than $100.
I think maybe his gear is rated for 2 different tubes. My bogen has 2 options for everything but the output tubes. They do not change. This technology really has all kinds of veriables
 
This is a hobby. I'm not sure what other hobbies some of you have been involved in, but even at the "top end", being an audiophile is pretty low budget. I have friends that ride $10,000 bicycles. I'm shocked when I see people crying about what some of the NOS specialty tubes cost, go price a Leica camera lens or what auto collectors spend. How much are we even talking about for this 6SN7 kit he wants to try, a couple of hundred bucks? I honestly am having a blast rolling different driver tubes in my amp matching them to different source materials. There is something special to me not using tone controls but by getting the EQ using the sonics from different tubes. Just because someone doesn't want to use an EQ, is no different than someone choosing a tube amp, or in my other passion photography, shooting film over digital. And in photography I see people saying "Oh just shoot digital and you can adjust it to look just like film, well no you can't.

It's his money, if he wants to spend it rolling tubes, doing amp mods or whatever and it makes him happy, why do people care?
This audiophile forum is very biased... you got us younger guys asking questions. Wanting to build. Learn and know if equipment we have is worth our time. If we can make it work. Then you have the guys that are older with some(alot) knowledge. They do not understand our motives sometimes. I for one. Think its great we have this club. Can talk to everyone. We all obviously have a common interest. I think its great that some of my generation learning and keeping alive. We should all remember that. Most people go buy new. We are the people that tinker. The IQ in other forums is much less im sure. We should all be supportive. And save rudeness for better reasons. Thanks audio karma
 
I like it. Standard VTA board in my somewhat modified Latino ST120 using a handy dandy converter socket in the middle, with matched 5814's in the sides. Plug and play with the appropriate adapter.

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As with any tube choice, lot depends on the brand. Currently running a '50's Graylock. That makes for a stronger midband, but also tends to push the bass a bit hard for my tastes. No problem - I run a "lighter" tube in my buffer to compensate. I bounce between the Graylock and a '60's era RCA coin base. Both are inexpensive "classic" tubes.

that amplifier--stunning
 
This audiophile forum is very biased... you got us younger guys asking questions. Wanting to build. Learn and know if equipment we have is worth our time. If we can make it work. Then you have the guys that are older with some(alot) knowledge.

Not to forget those of us who've gone full circle and are back to asking questions. I'll pat myself on the back saying I've done some pretty neat electronics over time, but now find myself challenged just figuring out how to turn the system on.

(then again, that was never all that easy) ;-}

Stereo-Block-Diagram-2013.jpg


PS - some talk about EQs ... use only as a last resort. Analyze room, add room treatments to get control over the big lumps, then use DSP software to take care of the details. More work, but it's a one time deal if you don't make any major changes, and well worth the effort.

Also, just say no to EQ ... PEQ is the way to go if you insist on pure analog ...
 
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