Thor, an all discrete Lateral FET Headphone Amplifier.
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diyAudio Member

Join Date: Oct 2004
Location: Aalborg, Denmark
Quote:
 Originally Posted by regal But this amp may also be an excellent cost effective amplifier for these new current hog orthos.
The amp modules should have no problem delivering transients of several amps, provided that the power supply is up for it.

Not that you would ever want to put several amps through your headphones, even for short transients.

But as with many other things, it doesn't hurt to have power in reserve.

diyAudio Member

Join Date: Oct 2004
Location: Aalborg, Denmark
Here is a rather crappy picture of a supply board PCB.

I completed a board today and so far it looks like it works.

However I only sent +/- 20VDC through it, so the real test is not before Monday when I can hook up my transformer to it.

If everything goes well, I should be able to test everything together on Monday, that means amp boards, supply board and no-thump board all connected together in my modushop alu case.
Attached Images
 DSCN1072.jpg (429.7 KB, 280 views)

 15th April 2012, 11:05 AM #93 diyAudio Member   Join Date: Oct 2004 Location: Aalborg, Denmark Just playing around with LtSpice simulations, testing the amp at no load(10Meg) and with a 32 Ohm load I get some interesting results. Output impedance of around 0.00114 Ohm and damping factor of around 28K with a 32 Ohm load. Unloaded(10Meg) shows peaks of 2.7795V which equals 1.98546099V RMS 32 Ohm loading shows peaks of 2.7994V which equals 1.98539007V RMS Calculating damping factor : (1.98546099/(1.98546099-1.98539007)) equals 27995.7838 Calculating output impedance : 32/27995.7838 equals 0.00114302926 Ohm
 15th April 2012, 12:45 PM #94 diyAudio Member   Join Date: Oct 2004 Location: Aalborg, Denmark Made an error : "Unloaded(10Meg) shows peaks of 2.7795V which equals 1.98546099V RMS" 2.7795V should have been 2.7995V. The rest is correct. A good paper on 0-Ohm impedance headphone amplifiers and the benefits they provide. 0-ohm-headphone-amplifier-sonic-advantages-low-impedance-headphone-amp Last edited by Neutrality; 15th April 2012 at 12:58 PM.
 15th April 2012, 04:40 PM #95 diyAudio Member     Join Date: Sep 2010 Location: Toronto, eh Looks like good progress so far...
 16th April 2012, 05:37 PM #96 diyAudio Member   Join Date: Oct 2004 Location: Aalborg, Denmark Well, hooked it all up today, no smoke, humm or buzz and it sounds great. Only problem is my No thump board, the AC detection doesn't work as it should, it doesn't work with AC applied to the AC detect connector. DC fine, AC no go. I'll have to figure out the issue tomorrow, but to be honest I'm rather puzzled by it. Simulation works absolutely 100% and similar AC detect circuits has been used with success for years by many others. But I'll have a solution sometime tomorrow. Edit : Think I have an idea why it doesn't work, but I'll look into it tomorrow Last edited by Neutrality; 16th April 2012 at 06:03 PM.
diyAudio Member

Join Date: Oct 2004
Location: Aalborg, Denmark
Got everything hooked up.

It works and it sounds great. No hum or buzz. No pop/thumps/crackles when turning on and no squealing/whizzing and similar noises when turning off.

Looks like everything is good to go.

What is left now is mounting the IEC inlet(with filter) in the backplane as well as the Neutrik RCA connectors and then solder the few wires I have left.
Attached Images
 1.JPG (627.9 KB, 178 views) 2.JPG (588.6 KB, 160 views) 3.JPG (753.2 KB, 165 views) 4.JPG (695.0 KB, 159 views) 5.JPG (750.8 KB, 79 views) 6.JPG (669.5 KB, 75 views)

diyAudio Member

Join Date: Oct 2004
Location: Aalborg, Denmark
Like I mentioned in a previous post, I had an issue with my No Thump board where a transistor had to be turned 180 degrees. The first picture I have attached shows that transistor.

Also, my AC detection didn't work. Well, I found the problem, I connected the AC detection wire going to my No Thump Board, to the wrong secondary on the Supply Board. Attached picture number 2 shows what is the wrong connection and what is the right connection.
Attached Images
 Thor No Thump Board 180degrees.png (172.7 KB, 68 views) Thor Supply Board yay or nay.png (42.5 KB, 59 views)

 20th April 2012, 01:35 PM #99 diyAudio Member   Join Date: Jan 2004 Location: MD Do you have any 1k FFT measurement to share yet ?
diyAudio Member

Join Date: Dec 2007
Location: Italy
Quote:
 Originally Posted by regal Do you have any 1k FFT measurement to share yet ?
Do you have 20k?
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"The total harmonic distortion is not a measure of the degree of distastefulness to the listener and it is recommended that its use should be discontinued." D. Masa, 1938

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