Monkeymatic Tamalpais - build in progress

[xtian]

Made time to drill the chassis and get everything mounted, transformer leads soldered. I love this stage!

[xtian]

Finished, tested, mostly awesome!

The B+ reducer is operating at -50v, giving me 375 on the plates and 371 on screens, 30v cathode (260R), 57mA per 6L6GC, or about 70%. I get about 25 watts clean output.

Sounds great. Tone stack is from 6G6B, including Treble pot with 70% tap. That's a very nice treble control! Bass control sucks, though, only useful from 0-2 on the dial, then no change--anybody improve this stupid thing?

I put in my own Middle control, which just increases the 6K8 tone stack shunt to ground from 6K8 to 259K. In operation, it's a nice Boost control that flattens out the mid scoop.

The Presence is working, but I think the frequency is too high because I can hear a lot of hiss increase, but it's at the top of the useful guitar voice. My gNFB feed comes from the 8R OT tap. Any help by swapping to another OT tap?

My heaters are at 7.2volts. I have ordered some 0.2R, 3W resistors to fix that.

Good news! The RGB LED strip I bought, along with it's microcontroller, do not radiate any noise into the amp.

[eniam rognab]

wicked pissah!!

[Smokebreak]

Nice work ! It's like a disco in there !

[matt h]

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[fusionbear]

very nice!

[xtian]

Thanks, y'all.

Disappointment is when you pedal downtown to get some stainless steel hardware to attach your handle and rubber feet, only to find that the damn hardware store closes at 5:30pm.

Good thing the Banshee is just around the corner. A Miller Lite and a shot of hooch at happy hour prices takes the sting out. And makes pedaling home a lot slower.

[xtian]

How many amps you see with a remote control included? OK, footswitches, sure. But this one's INFRA-RED!

[matt h]

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[davent]

Just saw this thread and i'll add my voice to those lauding the handling of the radial PS caps, inspired, thanks for shedding the light!

Great build!
dave

[xtian]

Thanks, davent. And matt h,

okay, enough with the pics... sound clip time.

You command and I jump:

https://www.youtube.com/watch?v=TCWv15J3rIY

[sunnydaze]

Great looking and sounding build and nice playing. Curious as to how it might sound without the GNFB.

Congrats on a great build.

Mike

[drew]

Needs one of these right in front of the OT.

[matt h]

(deleted)

[xtian]

Speaker? Notes copied from youtube vid:

New custom build. Preamp is Normal channel of Tweed Bassman 6G6B. Power section is cathode biased 6L6GCs with 375 on plates and about 25 watts clean output.

Maple (kitchen table!) cabinet features an audio-responsive string of RGB LEDs.

Recording is Agile AL3000 with GFS mini humbuckers straight into amp, Celestion G12T-75, SM57, MOTU 828mk3, no compression nor effects.

I need to consider my next move--to reduce or limit amount of gain. With Gain control dimed, it's on the edge of blocking distortion, or oscillation, or something ugly. Might be preamp tubes. I need to try other tubes in V1--have only heard my first grab, a Hammond made in Holland 12ax7. Seems ok, but might be a bit microphonic and unstable.

Matt, you wanted to hear it without gNFB. But this amp is too hot right now. I already changed NFB resistor from 56K to 22K to tame it.

My screens are only 4 volts lower than plates. Would you recommend a larger drop?

Maybe I need a voltage divider to drop some gain? I don't think I really want to do that.