Unused halves of the 12AT7s

[Natural Sound]

Any update on how you guys are going to utilize the unused halves of the 12AT7s?

[caffeinator]

Hi there,

I am not really familiar with the Stereomour, but having looked at this problem before, if one uses dual triodes in pairs in a configuration which leaves one of the triode pairs unused, it is possible to wire opposite channels (or opposite monoblocks) such that one channel/amp uses Triode 1, and the other uses Triode 2.  Alternatively, one could wire up a pair of adaptor plugs that achieve the same end.  In either case, swapping the tubes from one channel/amp to the other at propitious times could even up the usage.

I ended up abandoning the project, though, because for one I couldn't see how to keep track of usage to take advantage of the scheme, and for another, I don't spend so much on driver tubes that it seemed worth the fuss.

[Natural Sound]

I know what you are talking about because I have a pair of Paramour II's.

The Stereomour is a bit different. The original Stereomour used a single 12AT7 that covered both L & R channels. The Stereomour II has 2 12AT7's. The product description states, "The unused halves of the 12AT7s will accommodate future upgrades. We have several cool upgrades for this kit coming down the pike."

So far two of the upgrades have been released. One is the DC heater supply. The other is the mourquiet stepped attenuator. I'm guessing that the next upgrade will be a shunt regulator that use the unused triodes. But I'm waiting for the official word from Bottlehead.

[Paul Joppa]

... it is possible to wire opposite channels (or opposite monoblocks) such that one channel/amp uses Triode 1, and the other uses Triode 2. ...

That is, in fact, the way the stock Stereomour is wired. This way, when a tube gets worn and tired, you can swap tubes and use the other (pristine and unused) triode halves.

Incidentally, in the original Paramour the 12AT7 was configured as an SRPP using both sections. We quickly decided that the C4S plate load on a single triode sounded better, and it also isolated the signal from power supply noise, so it became the standard.

[Natural Sound]

Thanks for pointing that out, Paul. I wired my Paramour II monoblocks that way. It didn't dawn on me that the Stereomour II was wired that way.

I guess I'll have to wait for the answer to my original question.

[Doc B.]

We're working on releasing the updated Crack amp kit with universal power transformer and a newly revamped assembly manual in the next few weeks. After that we will be releasing an input stage shunt regulator upgrade for the Stereomour II. Probably late August/early Septemberish.

[gstitt]

Looking forward to the shunt regulator upgrade. Thanks!

[Natural Sound]

Thanks for the update Doc.