Monkeymatic Lassen (Supro 24)

[Reeltarded]

Amp sounds awesome!

Stay out of this. I'm busy dissin' his sub-hairdryer scooter thing.

I wonder if Aqua-Net sticks to paved road...

[xtian]

Lassen #2 is in the works. This one is simplfied: no tremolo; single, dual-gang Volume; single dual-gang Tone.

I bought a vintage Peavey Backstage Plus as the donor cab/chassis/speaker (10"). Should make for a nice little grab-and-go.

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[xtian]

My Peavey Backstage Plus arrived. It is, as I hoped, a solid little USA-made amp. In fact, it's very good sounding! I feel sad about RIPPING ITS GUTS OUT.

Oh, well. Can't make an omelette without breaking some eggs.

#RIPlittleamp

[xtian]

Good progress today. Fabbed chassis from 0.090" aluminum, got everything mounted, and wired the heaters, PT and OT.

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[xtian]

Finished, fired up, perfect. Waiting on rivnuts for mounting, and have to order a faceplate.

My efforts toward making my own layouts introduces new hurdles. While it's nice to have the preamp tubes close to the pots, the tubes are too close to the speaker frame when installed into the chassis. I'm going to make a new speaker baffle to solve this issue.

And I put many of my components too close together. No real trouble here, other than a PITA to work in such tight spaces. And no need, really, with such a large amount of free real estate inside the chassis.

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[sluckey]

Very clean and well organized design. I like it!

[pompeiisneaks]

I dig it, very nice!

~Phil

[xtian]

Tech stuff: 350v on plates, 26.4v across cathode (so, 323.6v effective plate voltage), 355R cathode resistor = 74mA. With 1KHz sine wave and 8R resistive load, output shows 12.5 watts clean power.

My innovation with this amp is to have a single, dual-ganged Volume pot, and a single, dual-ganged Tone pot. This worked out very nicely. The perceived taper on both controls is very gentle and smooth. And the "tone" of the tone control is very useful from dark to bright. A real winner in a tiny, lightweight package. I've really enjoyed both of these Supro-inspired builds I've made recently. Good circuit!

[xtian]

Faceplate arrived.

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[sluckey]

Nice job! I love seeing these old style Peavey SS amps turned into a nice tube amp. Looks way better than any Supro I ever saw!

[pompeiisneaks]

outstanding!

~Phil

[M Fowler]

Great looking build

[Mike-t]

Food for thought if someone is building something similar. On the original 24 and its variations you can jumper the inputs from channel one to channel two which gives a unique sound. For that reason it may be worth keeping two channel one inputs and one channel two input so you can achieve this. Or some switching wizardry to achieve the same effect.

[sluckey]

Food for thought if someone is building something similar. On the original 24 and its variations you can jumper the inputs from channel one to channel two which gives a unique sound. For that reason it may be worth keeping two channel one inputs and one channel two input so you can achieve this. Or some switching wizardry to achieve the same effect.

I used a single jack and a switch to do just that. No wizardry though. Been doing that on several dual channel amps lately.

[Mike-t]

In your description I interpreted it as a switch between channels and not to blend them, that makes sense then.