JLH Headphone Amp

Remember that when you want to put the 2 secondaries together to form at center tap, that tey must be put in series. Check that it is right by measuring the two ends, the voltage shall be twice the value of one secondaries.

Thanks oz7aff,
I did measure 24V from two ends, from center tap to one secondary 11.88V, from center tap to the other secondary 12.04V. I thought that was acceptable.

Kind regards
Marko
 
Jean, you must have deleted your post asking about the supplier of my JLH board. I did get the message by email !

Your problem appears to have been solved. In any case, I made my own board, which isn't great. Been planning to update it as soon as I have time but want to add a protection circuit ( relay) so that just in case there is a large dc offset it shouldn't fry my expensive phones. I run my amp on +/- 12 volts and it sounds very good. The supply is regulated by LM7812/LM7912 chips.

I notice many people having severe offset on power on and the offset settling down after some time. I will check this on my amp which is a straightforward implementation of the JLH circuit. The heat sink size is critical to keep the temperature down and reduce drift. I remember seeing only low offset voltages on it. But I could be wrong.
Cheers.
 
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Hi, yes I just scanned through the thread and board the bare board on eBay. I think I can come up with the BOM using Miles posts, but need to know what heatsinks to order that will fit the board exactly.

I use Sony MDR-7506s as my headphones, hopefully this will satisfy me, but it is my first dedicated headphone amp. My main amp is a diy p3a based dual mono, powering my diy scanspeak 3 ways.
 
Hi, yes I just scanned through the thread and board the bare board on eBay. I think I can come up with the BOM using Miles posts, but need to know what heatsinks to order that will fit the board exactly.

This is the heat sinks that I have used:
12pcs Transistors TO-220 Aluminum Heat Sink | eBay

I have no BOM, but a checklist

220p
330p
0u1
2u2
100u
2200u
2V7
4007
4148
LED
7812
7912
KLEM3
CON3
KLEM2
10K TPOT
10k Vol POT
2R2
5R1
22R
100R
470R
1k
2k2
3k3
4k7
220k
2N2222
2N2907
TIP41
Heat Sink
 
Ebay JHL Headphone amp

Agree with Hotiron, far easier to buy fully assembled and tested board then remove/replace the half dozen components to make it sound great.
Best $30 i ever spent, after a few modifications of course. Recommend you keep the DC output offset bias circuit, but you need good filtering to avoid hum coupling into your input stage transistor. Follow the thread, all the information is there. Good luck with your build. Post some pics.
 
The board linked by Hotiron looks nice. But the input cap is questionable. This can affect the sound if it isn't good. You could start with it and see if other film caps are better. However they might not fit on the board and could be placed near the input RCA sockets.
At least it is some place too start ! :)
My board just has a long heat sink ( plain 1.5 mm aluminum strip) on each side of the board. I wanted to make the new board so that it can sit directly on one finned heatsink. Need to find that heatsink first !