Thor, an all discrete Lateral FET Headphone Amplifier.

[Neutrality]

You want measurements?



If all goes well I might have some 1K and 20K FFT's on Monday.

I will test the amp with a 32 Ohm load and 1V RMS, maybe 2/4V RMS as well.

Also, If I have time for it I might include a frequency response plot.

But I wont promise anything.

[regal]

Just meant w/ a sound card 1Vrms out tells a lot. No biggy just curiousity.
Lateral mosfet headamp is a bit of an innovation I think.

[Neutrality]

Originally Posted by regal

Just meant w/ a sound card 1Vrms out tells a lot. No biggy just curiousity.
Lateral mosfet headamp is a bit of an innovation I think.

Well, I have access to a few different spectrum analyzers at work so I should be able to do better than a soundcard FFT.

I don't know if it is an innovation as such, but from googling there doesn't seem to be any similar designs with Lateral FET's.

[Neutrality]

I have sold a few PCB's so far but now that I'm done with designing all the PCB's and everything works as it should I have a bunch of PCB's left from V1 of my amp.

They are all fully functional.

Only issues are :

Amp board : Have to bend the legs of the 2 compensation caps if you are using Silver Mica caps or any other cap that wont fit otherwise.

No Thump Board : Have to rotate T1 180 degrees compared to silkscreen.

Supply Board : Have to use the other secondary for AC detection. Connector was added to the wrong secondary.

For this reason they are sold for a fair price.

2 x Amp Boards + 1 x No Thump Board + 1 x Supply Board is included in a set of boards

What I have left of V1 is :

2 pairs of Amp Boards left(maybe 3 if one can live with the soldermask being a little lumpy in some places)

9(or 11) No Thump Boards

10 Supply Boards

Price will be $30 USD for a set of V1 PCB's of which I'll be donating $3 USD to Diyaudio.com.

All boards are almost done being upgraded to V2(MKII) and I have fixed the few issues mentioned earlier as well as rearranging a few components, of which the Amp Boards will see the biggest change. One can see my Amp Board MKII in an earlier post. I'll be posting the final versions when they are done and I have the time for it.

Boards will be upgraded to MKII as needed. Once all boards are upgraded to MKII the price will increase to $40 USD for a set, of which I will be donating $5 USD to Diyaudio.com

As I mentioned in an older post, I'll be supplying schematics as well as a rudimentary BOM for all boards. So people will have to source their own components.

[Neutrality]

Attached is schematics and a rudimentary BOM for each of the current V1 boards.

[Neutrality]

There will be measurements tomorrow.

[qusp]

hmm ok still on the sidelines, but i'm about to clear a few things off the bench, so maybe, i'll see how the pocketbook feels, maybe i'll get the gen1 if theres any left on the weekend. either way its a cool design, maybe i'll throw some double die laterals at it ha

[Neutrality]

I'm using a Stanford Research Systems SR780 2-channel network analyzer for the measurements.

The built in generator is worse than I expected, but the measurements should still give an idea of what the amp can do. Dynamic range of the SR780 FFT is limted to about 80-90 dB and the max frequency is 100 kHz, good enough for 1kHz but not ideal for 20kHz but it will have to do.

First 3 attached pictures are 1kHz generator output at 0.7Vpk, 1.4vpk, 2.8Vpk.

Last 3 attached pictures are 1kHz amp output at 1Vrms, 2Vrms, 4Vrms into a 33 Ohm dummy load.

Amplifier gain is X2

Generator distortion is 0.7Vpk/0.021% THD, 1.4Vpk/0.011% THD, 2.8Vpk/0.007% THD.

Amp distortion is 1Vrms/0.015% THD, 2Vrms/0.033% THD, 4Vrms/0.072% THD.

The somewhat high distortion of the generator as well as the limited dynamic range of the SR780 FFT puts a limited on how good I can get the measurements.

I do have access to an audio analyzer from Rohde & Schwarz and I might try using that some day, it might have better specifications.

Next up is 20kHz measurements.

[Neutrality]

First 3 attached pictures are 20kHz generator output at 0.7Vpk, 1.4vpk, 2.8Vpk.

Last 3 attached pictures are 20kHz amp output at 1Vrms, 2Vrms, 4Vrms into a 33 Ohm dummy load.

Generator distortion is 0.7Vpk/0.035% THD, 1.4Vpk/0.0135% THD, 2.8Vpk/0.007% THD.

Amp distortion is 1Vrms/0.019% THD, 2Vrms/0.045% THD, 4Vrms/0.09% THD.

[Neutrality]

After checking the specs of the R&S UPL Audio Analyzer I think I might be redoing the measurements some day. It only goes up to 110kHz, but has lower generator distortion, higher dynamic range and the noise floor is between -120 and -140.