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Modulus-86: Composite amplifier achieving <0.0004 % THD+N.

I found these in my lab: Modulus-86 Rev. 2.3 fully built and tested. I occasionally build these so I can take build pictures and measurements for the design documentation. I guess I never got around to selling these.

I'm willing to part with them for $399 for the pair. You can find them here: Modulus-86 Rev. 2.3 Matched Pair | Neurochrome :: Audio

There's only this one pair, so if you don't see them in the Power Amplifiers section of my website, it's because they've sold.

Tom
 

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sorry but i don't see a thread on the upcoming HP-2 headphone amp, so please allow me a quick question here. is there any chance we can have a "populated but no chassis" option? otoh, are you using takachi for the enclosures?

I'll start a thread once I have a prototype to show off. I'll go with ModuShop for the enclosures.

The HP-2 will be an all-DIY project. You will be able to order the bare PCB (no parts) and the chassis from me.
I'll probably put together a "chassis package" that has the volume knob, mechanical bits, and screws that you need to put the PCB into the chassis. That'll save you from having to order from multiple vendors.

By "all-DIY" I mean that you solder everything. All parts will be leaded. I will not offer the HP-2 as a fully built product or as a partially built PCB. I will also not offer the HP-2 as a kit. You buy the PCB and the chassis from me, and you source the parts to build it. I'll provide my usual stellar documentation and link to Mouser.

If you prefer to buy a complete amp, I suggest you have a look at my Tom Christiansen Audio brand. My HPA-1 is pretty state-of-the-art.

Neurochrome will continue as my DIY brand. TCA will be my retail brand. Neurochrome designs will NOT be available under the TCA name. TCA designs will NOT be available under the Neurochrome name. The designs are created from the ground up as either a DIY product or a retail product.

Tom
 
No. The THD of the amp is below the integrated noise of the analyzer.

The only way I can measure the true THD of the amp is by using a precision oscillator. Even then, I run into trouble as the analyzer section of the APx525 "only" has 125 dB dynamic range. I.e. its internal distortion is -125 dB. I'm working on getting some filters together such that I can attenuate the fundamental, thus, measure the distortion residual.

Tom