2023 Monkeymatic Black Butte Desktop #4

[xtian]

Somehow, these weird, little amps keep selling, and I want one around the shop, so I'm building a new one. This one gets one noval and one octal power tube socket, wired in parallel, so I can plug in any single power tube, and adjust the cathode bias externally with an adjustable wirewound resistor. Finished dimensions will be 11.5"w x 7"d x 2"t.

Screenshot 2023-03-16 at 12.37.00 PM.png

[Reeltarded]

Confusing.

Where is the rest of it?

[mhuss]

I have something similar that'd I've used in my shop forever. The main differences between the two are that I don't have the noval socket or adjustable cathode resistor, and I'm using a tapped Hammond OT, so I have three output jacks "Lo Z, Med Z, Hi Z" I also have bypass switches for the second triode and output stage caps for lower gain. https://mhuss.com/amps/beast/index.html

[xtian]

I have something similar that'd I've used in my shop forever. The main differences between the two are that I don't have the noval socket or adjustable cathode resistor, and I'm using a tapped Hammond OT, so I have three output jacks "Lo Z, Med Z, Hi Z" I also have bypass switches for the second triode and output stage caps for lower gain. https://mhuss.com/amps/beast/index.html

Nice! Simple, tweedy, and rockin'--am I right? The only feature missing from yours that I now spec as mandatory is a CRC input filter to squash the single-ended hum.

[xtian]

Progress.

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[maxkracht]

Nice, looking good! I would be paranoid about someone popping two output tubes in there or cranking the bias but that vr looks intimidating enough to make someone pay attention. The tube socket pcb’s look rather convenient.

[dorrisant]

Very cool. I will pull up a chair.

Kuddos to you for a build post. I need to slow down and do one again.

[xtian]

Done, and won. No hum at idle.

PT: unloaded 296vAC (no CT)

Russian 6n6c (6V6GT)
123vAC wall voltage
378R cathode, 313v plate - 16.9v cathode = 296v = 44.7mA (100% = 47.5mA)

Load v watts:
4R = 4.4w
8R = 4.5w
16R = 3.2w

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[dorrisant]

Well, that didn't take long.

Looks great. Any clips?

[xtian]

Well, that didn't take long.

Looks great. Any clips?

No new clips, because it sounds the same as the other three desktops and 22 other Black Buttes I've built. Predictable and good! Here's an older demo:

[dorrisant]

Great tones, great playing. Thanks for that!!

That would be a great way to test tubes for sound... So I must build one. I may have to collaborate with you to engrave the plates correctly.

[xtian]

That would be a great way to test tubes for sound...

Precisely my reasoning.