SuMIX Headphone Amplifier

Tonight I've built the headphone amp, and tweaked the design to achieve lower distortion (noise is now the  dominant factor).  30R headphones you're looking at around 0.01% distortion at 1kHz when pushing 120mW into the headphone (unlikely!). For 600R headphones you can go even louder with even lower THD, and then I'm starting to reach the limits of my HP distortion analyser (below about 0.005%).

--Neil

First panel mock up of SuMIX

As hinted at earlier, the next module I'm working on is an output summing mixer for the Eurorack format.  And here is the first view of the front panel.

Ignore the blobs on the corners, those are just for aligning the artwork with the panel mechanics.
Also this shows representations of the panel furniture (knobs, leds, jacks, switches) to give a better impression of how it might look.
And thanks to Cody for his useful input :)

DuaLFO Goes Even Slower!

After some discussion on muffwiggler I ran a test to see how slow the DuaLFO could really go with a negative CV input.  Internally it is limited to -0.6V, so I applied -3V just to make sure.

Using my Heath-Robinson-style low frequency counter I measured the period to be about 8,833 seconds, or about 2 hours 27 minutes.  Now that's slow!!!

On to the next one

Now that the DuaLFO is finished and shipping it's time to start work on the next module.  This time it's going to be an audio mixer.  And I think it's going to be very interesting.

DuaLFO Now Available

The first (short) run of DuaLFOs is complete and ready to ship.  Get'em while they're hot!

Auxiliary LFO Equally Slow

Last night I ran the same tests on the Auxiliary LFO.  It has the same maximum frequency of 46Hz, but if anything it is slightly slower than the Main LFO.  I recorded a run of 1 hour 35 minutes.

I think that's slow enough....

Main LFO Goes Slow

Last night I finally characterised the frequency range of the Main LFO of the DuaLFO.  And it is quite a range!  Highest frequency was 46Hz.  Pretty good.  The lowest frequency?  Well, probably better to think of the period rather than frequency.  In this case I measured the period to be 1 hour 25 minutes.  Or, in frequency terms, that's 196 micro-Hertz!

SSssssssllllllloooooowwwwwww...................

Next is the Auxiliary LFO, but I'm guessing that it will have similar performance.