[bigsled]

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

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

If I use  certain tubes known for say their  clarity and the  other two for tubes for say their warmth do they compliment/balance each others strengths  or doesn't it work that way?

I really don't know how it works  for trying different brand tubes' sound     

Thanks   

[richidoo]

Welcome to Audiocircle, bigsled!

You have the right idea.

There's lot of opinions about tubes, but in the end you still have to try different tubes and see what you like. Best to listen to the advice, then trust your ears. And don't go nuts chasing exotic vintage tubes. It's just not worth it, imo. Some of the new tubes are excellent now. 

Yes, you can mix brands, but keep each tube type the same (brand and batch) on each channel, so left and right will match in volume and tone.

I have done well over the years with advice and tubes from Jim McShane. I have no affiliation with him, other than happy customer.

An interesting article about JJ 12AT7 https://syclotron.com/the-red-light-district-p3/

I would use Tung Sol 12AT7 and Genelex Gold Lion 12AU7. Their tubes are the best of the mass produced new tubes now, imo.
I prefer the tonal clarity, availability, consistency, price and warranty of new tubes.
ymmv

[Chewbacca]

Hi Bigsled, and welcome to AC!

I'll shine what light I know on the subject, but my disclaimer is that I'm sure the next guy will know more than me!

You can absolutely swap tube brands between the gain stages of the amp! Of course, this means do not have different tubes for the same stage - For instance if you have two 12au7's, one for left speaker, on for right, of course those need to be the same, and ideally a matched pair.

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.

Not sure if that at all helps you in the start of your now neverending tube story

[trebejo]

Good to see Jim McShane and new production tubes getting some luv.

The search box gives this nice survey by Larry Jenkins,

https://www.audiocircle.com/index.php?topic=2557.msg20544;topicseen#msg20544

That was a while ago so it may be more of a NOS/culture/YesWeDoCheckTheseThings kinda thing. However, if one is starting on the (insert_adjective_here) path of tube rolling, one can get an idea of just how involved, prolonged, and delicate the project can become.

The other day I was thinking that tubes are like amorous relationships, and some audiophiles are pathologically monogamous whilst others are incorrigible flirts. But I'll probably change my mind...

[sebrof]

I have done well over the years with advice and tubes from Jim McShane. I have no affiliation with him, other than happy customer.

Same here

[bigsled]

Hello

So unfortunately  I was out of the listening world for a number of months do to some medical problems .


The preamp is
using  2- 12AT7 tubes for gain and   2- 12AU7 tubes as cathode followers.
So far I've put in Mullards in the AT7 spots and left them in.
I've tried a few brands in the AU7 spots and have noticed  changes in sound each time.

My question  is am I suppose to just switch the " gain" tubes or the "cathode followers" tubes for sound or both, in which case wouldn't Chewbaccas post apply ( you can't add/ take away sound further down the chain) ?

2nd question is someone's quote on another forum was this :

 "Anybody who has ever built gear or rolled a lot of tubes knows that two good preamp tubes from the same production code can sound vastly different - not to mention sonic differences due to minor changes in plate and heater voltages".

Thoughts on this statement ?
I ask because as I try different friends tubes and decide if I want to get same ones too ( from same dealer) I wonder if they will sound the same ( minus burn in period )

Thanks everyone