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Topics - jfetter

Tubes and Hybrids / Hybrid valve and TPA311x
November 15, 2018, 07:52:42 PM
Two years have tested others and this one sounds the best.
I built it point to point but now doing a board.
The tone tilt I think beats all others. Shown here in hifi mode but easy to add scoop.
Uses 12AU7 and $3.00 D class module.

Schematic attached. The fx loop is not fully tested.

Schematics and Layouts / More hybrid madness
September 21, 2017, 03:31:53 PM
Threw this together, its still on proto board and running tests. I'm crazy about fets and tubes together.

Jury is still out on this one, have to play it through my system.

Working on a new one now with some improvements, ie compressor so D amp never approaches clip.

As-built zip attached.

Preamps and Effects / dspic-codec
December 23, 2011, 12:50:48 PM
I finally got the dspic preamp board done. Is any one else doing 16bit (_Q15) dsp?
It sounds great with no noise whatsoever. Running three filters now low,mid,hi.
Not much on the internet or from Microchip on pro-audio apps. Some of the old Analog Devices code works. The 16 bit works great for this app.

I need a good integer q15 reverb and a soft limiter.

This board is not a finished gadget. It is only for developing dsp code. Has six control voltages. Audio path is 100% digital.
Amplifier Discussion / Class A solid state
December 15, 2008, 05:56:23 PM
hi im back....

doing a new design, i once biased a germanium doorknob power resistor 1/2ps and ran simple class a. it has a special sound for sure. ebay has lots of russian germanium transistors.
the physics may be more complex then simple spice circuit analysis. not sure but it sounded really good. problem is dumping all that heat. my test was a 10 watt unit, gets too hot.

has anyone tried ss class a guitar? ive studies the jlh and variants , think simple class a is best. mosfets better?

ps ive switched to eagle layout.
Does this look like it would work? The feedback position looks problematic.

Preamps and Effects / Boss/Fender FD-1 and FBM-1
May 09, 2007, 11:41:16 AM
I'm impressed with these pedals from the tone demos at

Don't own one yet. Has anyone disassembled? Please show pics.

Anyone have the Orcad 'layout' library for the Pentawatt (TDA2030A and TDA2050). I have the schematic 'Capture' library from ST, no footprints though.