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Multi tubes amps what effect does each has?

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Multi tube amps what effect does each have?

If a tube amp has say:
300B x 2 (only these have a bias dial)
6N8P x 2
12AT7 x 2
5Z3P x 1 (rectifying tube)

  1. What effect would changing each have to an equivalent model in a different brand? Like say 12AT7 PSVane to Genalex?
  2. Which would have the biggest change?
  3. Would they all need to designed to work with each other?

Thanks, I'm a tube n00b, and couldn't find the answer.
 
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What you describe is known as tube rollling. While there is no guarantee, "rolling" the small signal tubes rates to yield the biggest change. For instance, you could replace the Chinese 12AT7s with NOS Mullard CV4024s. The 6N8P seems to be a 6SN7 "equivalent". New Sensor's "reissue" TungSol is worth trying. Desirable old stock 6SN7 variants command silly prices.
 
Thanks, so there are no rules on effect.
Eg: changing the 300B's to Genalex will increase dynamic range slight; > output power...

Or change tube X affects mids...
What if tubes are bypassed electrically?

Why would one change the 12AT7's if I don't know what the outcome will be? change until it breaks or if it ain't broke, don't change it.
I mean the above with utmost respect, but I would like to learn without blowing money.

I can't find the link now, but last week I read this guy tube rolled a whole bunch of 300B's and the difference in out put was described in very colorful terms... like tube X was flat and boring, tube Y was dynamic and engaging with very deep lows and bright highs; was the dude tripping?

Also some dude with my amp on utube said it was crap until he changed the tubes... I asked him which tubes he replaced > no reply.

Any insights people have I would appreciate, again I'm a tube n00b so if this question has bagged like audio cables and motor oil... sorry.
 
Is he trippin, on the money or a paid reviewer?
If I were to just roll out the 300B would I notice the difference or would I also need to roll out the other tubes?

You will notice differences. Whether they are there or not, you will still notice them.

M2CW, WoS is FoS. But at least his disclaimer is honest.

Additionally what role does each set have.
So I believe:
1.- 300B's are Output tubes.
2.- 6N8P Preamp tubes?
3.- 12AT7 ???

Without a diagram hard to say, but probably 1 = outputs, 2 = drivers and 3 = voltage amp/phase splitter
 
Without a diagram hard to say, but probably 1 = outputs, 2 = drivers and 3 = voltage amp/phase splitter
I found this

MS300C-schematic-modifications.jpg
 
NOS 12AT7s are cheap - pick up some Tung Sols or RCAs or whatever - no reason to go expensive, and see if they make a difference. It will probably be slight (if any) but at least you don't have a lot of money invested in the experiment.

I'm not a big fan of new 6SN7s - I would try out some GEs which are still inexpensive - at least they will last longer and may have lower microphonics.

300Bs are expensive - even the "bottom barrel" ones and tube rolling here would be pricey. I always used EH Golds = because, at least in the amps I built, they were rugged.

Just wanted to add that's a whole bunch of circuitry to drive a 300B. But I like pentode drivers, so what do I know ;)
 
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