It would certainly be "easier" from a physical labor standpoint

Using three 6CG7s would only involve cutting a few traces on the circuit board, and soldering in six jumper wires. Installing the octal board involves removing and reinstalling more wires, as well as the hardware of the board itself. Not that that's a lot of work, but technically it is more work. But buying a new octal board would allow you to sell the used 12AU7 version, along with the adapter, so there's that.

But the real question, one that Airtime and I have speculated on, is how much sonic improvement (if any) would be gained by changing the phase inverters (the two outer tubes) to 6SN7s or 6CG7s.

He even posted the question to the Asylum, and possibly elsewhere, but I don't know if he was fully inspired by any of the answers he got. If I needed a new board, I wouldn't hesitate to buy the octal version. But since the VTA ST-70 isn't my main amp, I'm going to stick with the 12Au7s in the phase inverter positions, at least for now.

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Follow Ups Full Thread

Topic - Follow-up on new build ST-70 with the 6NS7 tube - JoshT 09:14:38 04/01/23 (20)

Just read yesterday... - Cougar 11:33:25 04/03/23 (4)

RE: Just read yesterday... - 1973shovel 11:46:49 04/03/23 (3)

I'm happy with the 6H8C... - Cougar 13:42:43 04/03/23 (2)

I'll be looking forward to your assessment - 1973shovel 08:32:18 04/04/23 (1)

I will do that... - Cougar 11:39:16 04/04/23 (0)

ST 70 - M3 lover 10:31:02 04/03/23 (1)

RE: ST 70 - JoshT 13:49:29 04/03/23 (0)

"All of that said, I don't hate the 12AU7s" - 1973shovel 09:20:36 04/03/23 (0)

What does the middle 6NS7 do? - Rod M 19:41:34 04/02/23 (1)

It's the gain tube as I understand it - JoshT 07:39:37 04/03/23 (0)

RE: Follow-up on new build ST-70 with the 6NS7 tube - Sondek 07:48:12 04/02/23 (6)

A 6CG7 could be used... - 1973shovel 09:09:23 04/03/23 (4)

Would that be easier than just replacing the driver board with the VTA Octal one? - JoshT 09:14:27 04/03/23 (3)

It would certainly be "easier" from a physical labor standpoint - 1973shovel 09:53:40 04/03/23 (2)

Thanks - JoshT 13:43:13 04/03/23 (1)

I'm glad it's working out for you (nt) - 1973shovel 07:09:09 04/04/23 (0)

I dunno - hope others respond though! - JoshT 07:46:44 04/03/23 (0)

Glad to hear you are.... - Cougar 19:33:19 04/01/23 (1)

Thanks! nt - JoshT 07:47:09 04/03/23 (0)

RE: Follow-up on new build ST-70 with the 6NS7 tube - Triode_Kingdom 18:16:42 04/01/23 (0)

Follow Ups

It would certainly be "easier" from a physical labor standpoint - 1973shovel 09:53:40 04/03/23 (2)

Thanks - JoshT 13:43:13 04/03/23 (1)

I'm glad it's working out for you (nt) - 1973shovel 07:09:09 04/04/23 (0)

It would certainly be "easier" from a physical labor standpoint

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