The Burning Amp Festival-Burning Gadgets Preview

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My experimental error correction / zero global nfb amp is playing. Beautiful, of course. ;)

Almost ready to travel. Only the protection to tweak.

Jan Didden


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diyAudio Moderator Emeritus
2002-10-24 10:19 pm
What's with the name?

It's designed specifically to drive the F4. So I couldn't resist the pun. (Zen Mod would have been happier if I called it "Smashing Pumpkins")

As you can see, it's a very simple design. No loop feedback. Gain of 20. Surprisingly low distortion at the 20V output needed. It will only drive balanced loads, but it's not supposed to be universal. Input tube is a CV1988 (British military version of 6SN7) from Morgan Jones's stash. Output tube is a "Bugle Boy" ECC88.

And surprise, surprise, active regulation, CCS loads, and LEDs. My design work does tend to follow a pattern.

Unlike Jan's amp, it will NOT be beautiful.
So, as you may have read elsewhere, I got the title of "award manufacturer" for this years event.

Now you can see what the awards turned out to be :)

I realize the pics are not the best, but it's dark here and I had no light handy, and couldn't move the knobs as the glue isn't hardened yet.

The materials are walnut and copper.....

So, if you want a set, drop by the event and show us something you've made :D

Magura :)
Attached is a picture of the "Almost Blameless" amp I'm bringing. This started as a training exercise in analog simulation I gave to a new guy at work. I gave him a back-of the envelope schematic for a basic amp so he could do some Orcad simulations and get a feel for a simple design and see what some changes would do to the operating parameters.
It started out as a simple JFET differential input stage, VAS, and darlington outputs w/VBE multiplier. I got hooked by the design myself, , added some buttons and bows, then decided to build it with what I had at hand, since the simulation results were very attractive. The design originally called for +/-30V rails, but the only transformer I had on had gave me a +/- 40V supply, and the darlingtons available (TIP142/147) had a pathetic SOA at 80V, so the output was changed to MOSFETs, and the VBE multiplier to a VGS multiplier. The amp was packed into an LMB box, and the result is shown below - plain but functional.


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