H2

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#223
I have been requested by one of the members (Carston.Witt) for the
Gerbers to the H2 board that was distributed at BAF, this for the purpose
of making them for a small group of DIYers in Europe.

Here they are, everyone is welcome to play with them.

Since they require matched Jfets, we will have to make some provision
for supplying those as well.

:cheers:
 

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#224
Nelson Pass said:
I have been requested by one of the members (Carston.Witt) for the
Gerbers to the H2 board that was distributed at BAF, this for the purpose
of making them for a small group of DIYers in Europe.

Here they are, everyone is welcome to play with them.

Since they require matched Jfets, we will have to make some provision
for supplying those as well.

:cheers:
Click to expand...

Any chance of a kit run for the diyAudio store?
 
#226
Nelson Pass said:
For the upcoming Burning Amp Festival I created a nice little 2nd Harmonic
Generator. It's similar to what the Korg Nutube does, but uses a Jfet.
Click to expand...

The DIY store already offers kits for the B1 with Korg Triode. If a kit for the H2 is realized, would you expect a material difference in the resulting sound?

Or does the B1 add the benefits of a buffer in addition to "tube" sound?

Just trying to understand the decision process a potential purchaser would have choosing between the two if the challenges of sourcing components are resolved by the DIY Store.
 
#230
Sanity check

I've put together a circuit incorporating Mr Pass's H2 generator followed by an inverting stage plus delay and bypass relays.

I stayed with the lone 24V input, so the op amp is running in single supply configuration.

How does this look? Any dumb mistakes?

H2.png

Feel free to suggest changes 😀. Once it's solid I'll post the gerbers here.
 
#232
Hi, I worry that in "bypass" mode you might have a deadly fight because the input to your box is shorted to the output of your box. If the input is from your phono preamp then it's fighting against the output pin of opamp U1.

Also you might prefer to connect R7 to (VFILT / 2) instead of to ground.

Inverse color palette (white blackground) image attached
 

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#235
Unless I missed reading a few posts, no posts have been related to actual use in a system and or subjective/objective benefits attributed to the H2.


After almost a year, I have finally completed my H2 "build" which included hard wiring the wall wart power supply, replacing the inexpensive RCA jacks with some of better build quality, adding an LED readout of the Output Voltage, putting into a extruced build box. I also fabricated short RCA jumpers for connection between preamp and H2.


Just installed in my system comprised of:

  • Mytek Manhattan II DAC;
  • Custom built LDR based preamp (similar concept to Tortuga);
  • XA60.8 amps;
  • Martin Logan CLX Art electrostats;
  • HSU VTF-15H MkII subs for stereo bass;
  • Velodyne F1200 subwoofer for ambient bass;
  • PS Audio P3 powering pre and DAC;
  • PS Audio P300 powering electrostats;
  • Harmonic Technology Photon interconnects between DAC/pre and pre/amps;
  • Anticable Level 5 speaker cables;
Was pretty excited about taking a test drive...until I powered up the amps (NOTE: system had been powered down for a couple of weeks previous). DAC and pre were not powered up. What I heard was a high pitched whine from the estats.


Any assist with diagnosis would be great.
 
#236
If I were in your position, the first two experiments I would probably try, are:

  1. Remove H2 box from audio system. Listen to audio system to discover if whine has disappeared or changed
  2. Move H2 box to lab bench, install shorting plugs on inputs, connect oscilloscope probe to output(s). Are oscillations / misbehaviors present? Remove shorting plugs and allow inputs to float. Now are oscillations / misbehaviors present?
These test results might help narrow down the list of possible reasons for the whine.
 
#237
Mark Johnson said:
If I were in your position, the first two experiments I would probably try, are:

  1. Remove H2 box from audio system. Listen to audio system to discover if whine has disappeared or changed
  2. Move H2 box to lab bench, install shorting plugs on inputs, connect oscilloscope probe to output(s). Are oscillations / misbehaviors present? Remove shorting plugs and allow inputs to float. Now are oscillations / misbehaviors present?
These test results might help narrow down the list of possible reasons for the whine.
Click to expand...


Thanks, I plan to do (1) as a first experiment...but expect NO issue since none before shutdown and no other changes made.


You are assuming I have a "lab" bench, oscilloscope, and shorting plugs!
NO in all cases no resource to outsource.
 
#239
Big Guy said:
Thanks, I plan to do (1) as a first experiment...but expect NO issue since none before shutdown and no other changes made.


You are assuming I have a "lab" bench, oscilloscope, and shorting plugs!
NO in all cases no resource to outsource.
Click to expand...


Talking to myself again...🙄


As expected removing the H2 eliminated the whine.


Question...


With the H2 removed from the system, is there any checks I can do with a multimeter? E.G., with the H2 powered, what should I see, if anything on the meter ...

with probes attached to the RCA input and output +'s?

with probes attached to the RCA input and output -'s?
 
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