[bigsled]

I have the Fet Valve CF RB by Van Alstine and wanted to know about trying vintage tube's for sound.
 "Rolling " as they call it .

This pre amp uses 2- 12AT7 tubes for gain and  2- 12AU7 tubes as cathode followers
I wanted to know if it makes a difference if all 4 tubes  in this preamp ( the two AT7 and two AU7 ) should be the same brand ?
Do both gain and follower positions produce sound changes ?
If I use  certain tubes known for say their  clarity in the " gain "  and the  other two for tubes for say their warmth in the " followers" spot do they compliment/balance each others strengths  or doesn't it work that way?
So far I've put in NOS Mullards in the AT7 spots and left them in.
I've tried a few NOS brands in the AU7 spots and have noticed  changes in sound each time.

My 1st post ( and only post so far) was not in the right circle so here I am.

A member responded to my questions above with the response below Including this sentence :   " you can't give back or add to sound changes further down the chain " .
So thats why I was wondering is it my GAIN or is it my FOLLOWERS the spots I would " roll tubes " ?

RESPONSE FROM A MEMBER :
Regarding one tube stage adding warmth one tube stage adding high treble extension for example... it does and does not work that way. Let me try to explain - My theory would be: a stage of amplification can only amplify the signal that is given to it. For instance, if you have a tube stage that completely takes out all high frequencies beyond 10khz, you cannot add another tube down the line that is known for high frequency extension and expect it to give back that extension past 10khz, or what was lost up the chain. It cannot add to something that is no longer there, once those frequencies are gone (up the line) nothing can give them back (in an analog world), it will only "color" what is still in the signal path. So, it's really a balancing act. Each tube is almost equally as important, as they all change the sound (some say rectifiers don't change the sound... but I would certainly disagree with that). But just know, if you have a tube that limits something early in the chain, you cannot give back what was taken away. You COULD for instance fool yourself into thinking you're getting back these things from other tubes/components down the line, but IMO it would only be in the form of distortion that you're leveling out your frequency response, or tonality to taste.




Thanks all
 I know it can be annoying responding/talking about the basics and most may rather not waste their time  .   

[jtcf]

I like those mullards you're using now btw.I found them to be the best input tube for a preamp I had in the past,just right in that they seemed neutral and very quiet. Then next pair of tubes (6NS7 in my case) I experimented with until I was happy with the balance of warmth and detail.They don't need to be the same brand. A lot of the small signal tubes are the exact same tube but rebranded for different companies. Visit Brent Jesse's website (Audiotubes.com) for a wealth of information about all things tube.Enjoy your journey:-)

[S Clark]

I use a phono pre with 12AU7's and 12AX7's.  I have old Mullards in place currently, low noise and musical sound.  Not the most detailed but so very easy to listen to.  I also have a set of Sylvania  Baldwin that are brighter in nature.  They are currently mounted, but I think I'll be going back to the Mullards.   

[FullRangeMan]

For audio I like low noise tubes what tube brokers rarely test.
https://www.youtube.com/watch?v=13n1VCR6UXw

[Ericus Rex]

You're actually fortunate in that the AT is the most sensibly priced NOS of the three 12A*7s.  The signal doesn't actually pass through the 12AU7s.  I won't say they don't have ANY effect on sound but definitely not to the level of change of the ATs.

[richidoo]

Welcome to AudioCircle, bigsled!

This pre amp uses 2- 12AT7 tubes for gain and  2- 12AU7 tubes as cathode followers
I wanted to know if it makes a difference if all 4 tubes  in this preamp ( the two AT7 and two AU7 ) should be the same brand ?

Using the same brand of tubes is not required.

Do both gain and follower positions produce sound changes ?

Yes, everything affects sound quality.

If I use  certain tubes known for say their  clarity in the " gain "  and the  other two for tubes for say their warmth in the " followers" spot do they compliment/balance each others strengths?

Bingo!

So far I've put in NOS Mullards in the AT7 spots and left them in. I've tried a few NOS brands in the AU7 spots and have noticed  changes in sound each time.

You have a good ear, and you are getting the hang of tube rolling. Better put your credit cards in a block of ice in your neighbor's freezer.

A member responded to this question with the response below my question to it would be if you can't  "give back or add to sound changes further down the chain " than are my gain or  my followers the the spots I would " roll tubes " ?

RESPONSE FROM A MEMBER :
Regarding one tube stage adding warmth one tube stage adding high treble extension for example... it does and does not work that way. Let me try to explain - My theory would be: a stage of amplification can only amplify the signal that is given to it. For instance, if you have a tube stage that completely takes out all high frequencies beyond 10khz, you cannot add another tube down the line that is known for high frequency extension and expect it to give back that extension past 10khz, or what was lost up the chain. It cannot add to something that is no longer there, once those frequencies are gone (up the line) nothing can give them back (in an analog world), it will only "color" what is still in the signal path. So, it's really a balancing act. Each tube is almost equally as important, as they all change the sound (some say rectifiers don't change the sound... but I would certainly disagree with that). But just know, if you have a tube that limits something early in the chain, you cannot give back what was taken away. You COULD for instance fool yourself into thinking you're getting back these things from other tubes/components down the line, but IMO it would only be in the form of distortion that you're leveling out your frequency response, or tonality to taste.

I would agree with that. But don't worry, your brain can sort out what is lost and what is "gained" (<-- PUN!!!) Go by what sounds good and you'll enjoy the journey.

A tube is only as good as it's circuit, so discount online tube hype where amps aren't discussed.

Also, have some backup tubes and fuses on hand so when they pop you aren't waiting for parts in silence.

I know it can be annoying responding/talking about the basics and most may rather not waste their time  .

It's always fun to help!! Let us know what you try and how it works out.

[Escott1377]

I previously owned a Manley Shrimp and it uses a pair of 12AT7’s.  The NOS Mullard is really hard to beat and they are priced reasonably.  I went down lots of rabbit holes to find subs, there are lots of options.  Another 1 of my favorite pairs was a NOS Raytheon from the US.  Tube Depot carries this tube: 7062 / E180CC.  It looks very interesting, is affordable, and has a review from Brent Jesse on the site.

I think you will find lots of good subs that are reasonably priced and will be fun to experiment.

Good luck and have fun!!

[bigsled]

Welcome to AudioCircle, bigsled!

Using the same brand of tubes is not required.

Yes, everything affects sound quality.

Bingo!

You have a good ear, and you are getting the hang of tube rolling. Better put your credit cards in a block of ice in your neighbor's freezer.

I would agree with that. But don't worry, your brain can sort out what is lost and what is "gained" (<-- PUN!!!) Go by what sounds good and you'll enjoy the journey.

A tube is only as good as it's circuit, so discount online tube hype where amps aren't discussed.

Also, have some backup tubes and fuses on hand so when they pop you aren't waiting for parts in silence.

It's always fun to help!! Let us know what you try and how it works out.

Which would you  say more affect the sound , the gain tubes or the cath follower tubes ?

I have been finding some discussions where some feel todays gear and their circuitry do not work as well with NOS or any old tubes.
Can't say if it is people in the industry that only sell new it was just something I seen a few times while surfing around.  Thoughts ?

Thanks Richadoo

[Escott1377]

The gain tubes should have a bigger impact.

I splurged this year and bought 3 x 6sn7’s from Brent Jesse and they are a big difference vs new tubes as I have a trio of Tung Sols to compare against.

New tubes are very good these days as well and my system is all new production in my tube mono blocs. 

I mentioned the Mullard 12 AT7 previously and it is not a big hit on you wallet.  You can get pretty pricey on the 12AU7 but I would buy the Mullard first and add the other tubes later.

Good luck and have fun!

[bigsled]

You're actually fortunate in that the AT is the most sensibly priced NOS of the three 12A*7s.  The signal doesn't actually pass through the 12AU7s.  I won't say they don't have ANY effect on sound but definitely not to the level of change of the ATs.

Interesting I will have to buy AT's

Thank You

[bigsled]

Well this will be exciting to start trying the AT's over the AU's according to everyone's feedback that this will affect the sound more.

I was kinda under the impression it was the AU's.

So beside having the AT Mullards I've tried some 70's Tesla's AU7's that were suppose to be a replica of some really rare and expensive  AU7 Telefunken long plates that were suppose to sound so great   
And  I tried some 1970 BRIMAR CV4034 Long Plate Military  AU7's which I felt sounded less bright and smoother then  the Tesla's ( which I didn't know where a little on the brighter  side  )
The Brimar also sounded fuller and more 3D which I loved .

Have I lost some detail by taking out the Tesla's or am I confusing that with smoothness and less bright 

Either way the Brimars sound nicer .
And  ,less fatiguing especially in some female vocals .

Can't wait to take out the Mullards and  try some Brimar ECC81/CV4024/12AT7 Halo Getter  a friend has but I wonder if they will be too close in sound to the Mullards seeing they are both British , similar years and similar price range ?

[NXSTUDIO-DRUMMER]

For audio I like low noise tubes what tube brokers rarely test.
https://www.youtube.com/watch?v=13n1VCR6UXw

Thanks for sharing, What eye opener. That's amost as bad, as having a snare wire strainer string break, on a snare drum, while recording in the studio. 

This is good to know, prior to purchasing tubes. Excellent pointer