If you like the Salas you should try the original Erno Borberly EB602.
http://www.audioxpress.com/article/a-battery-powered-class-a-headphone-amp
index
Patrick
http://www.audioxpress.com/article/a-battery-powered-class-a-headphone-amp
index
Patrick
15V Rails, OPA2604, but not your PCB used my own layout #441
Tested without poti, no strange behavior.
...but i need a pot if driven from cd Player directly.
I have never been an audioxpress subscriber but nice to now see that the great Erno had worked along similar lines for an hp amp in the past. It would have saved me lot of head-scratching and several breadboardings in topology experiments to end up near there once again if I knew better. Patrick, thanks for the link I will save it to read later in detail.
See also :
https://linearaudio.nl/sites/linearaudio.net/files/BorbelyAnnalsMMM508.pdf
As well as the 2nd link above where he discussed with Mr. Tubecad about his preference of active devices.
I spent some months thinking about why he did certain things his way in the EB602.
Very educational.
But we should stop hijacking Wayne's thread.
Patrick
https://linearaudio.nl/sites/linearaudio.net/files/BorbelyAnnalsMMM508.pdf
As well as the 2nd link above where he discussed with Mr. Tubecad about his preference of active devices.
I spent some months thinking about why he did certain things his way in the EB602.
Very educational.
But we should stop hijacking Wayne's thread.
Patrick
Yay, I got my Pass Diy headphone amp cased up today. Nothing fancy, just an old tube headphone amp case (modushop) being re-used. Only initial listening going on but it sure sounds promising. The build was quite straightforward without any hick-ups. Thanks a lot to Wayne for all the effort!
I'm using Toshiba FETs (liubincalvin), Nichicon/Panasonic caps and Dale RN60 resistors. The opamp is at the moment LM4562, but I have OPA627 and OPA2132 waiting to be tested. The input caps are now basic Mundorf MKPs, but propably they will get upgraded to Evo Oil versions later on.
I'm using Toshiba FETs (liubincalvin), Nichicon/Panasonic caps and Dale RN60 resistors. The opamp is at the moment LM4562, but I have OPA627 and OPA2132 waiting to be tested. The input caps are now basic Mundorf MKPs, but propably they will get upgraded to Evo Oil versions later on.
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And we'll have a table to audition Wayne's Amp . Bring your headphones if you want to hear how it will sound into them.
I've been remiss in keeping him informed about the show. He will be giving a short talk, 1/2 hr plus 10 min for questions, which will discuss this amp but we hope mostly give some general observations about his approach to audio.
Mark
I've been remiss in keeping him informed about the show. He will be giving a short talk, 1/2 hr plus 10 min for questions, which will discuss this amp but we hope mostly give some general observations about his approach to audio.
Mark
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Oscillation?
Yesterday I tested the OPA627 after trying LM4562, but I had some strange problems with it. On the right channel I could hear a hissing noise, but the left channel was dead silent. Also the left headphone warmed up a bit. When I switched the power off the led ring in my power button dimmed slowly indicating that the voltage from positive rail dropped very slowly. Also the heatsinks for 2SK2013/2SJ313 felt colder than with LM4562 opamp. I used Apple iPod standard plugs for these tests and didn't have the courage to plug in my Audeze's.
After this test I plugged in OPA2132 and everything worked normally. Could it be that I'm suffering from oscillation? My circuit is almost in stock form: I have 2.2k resistors for R4/R8 to lower the gain and I have implemented the optional C2/C7 (Kemet PFR 100pF). Should I perhaps try to remove the C2/C7 caps to make it work with OPA627? Also the input caps C1/C5 are 2.2uF when schematic cals for 1uF, but I suppose this shouldn't matter in this case.
Anyway I think the OPA2132 was a clear improvement and the bass sounded deeper and more controlled. Would be nice to test the expensive OPA627 too.
Edit: Oh, and I'm using +-15 VDC configuration from the power supply.
Yesterday I tested the OPA627 after trying LM4562, but I had some strange problems with it. On the right channel I could hear a hissing noise, but the left channel was dead silent. Also the left headphone warmed up a bit. When I switched the power off the led ring in my power button dimmed slowly indicating that the voltage from positive rail dropped very slowly. Also the heatsinks for 2SK2013/2SJ313 felt colder than with LM4562 opamp. I used Apple iPod standard plugs for these tests and didn't have the courage to plug in my Audeze's.
After this test I plugged in OPA2132 and everything worked normally. Could it be that I'm suffering from oscillation? My circuit is almost in stock form: I have 2.2k resistors for R4/R8 to lower the gain and I have implemented the optional C2/C7 (Kemet PFR 100pF). Should I perhaps try to remove the C2/C7 caps to make it work with OPA627? Also the input caps C1/C5 are 2.2uF when schematic cals for 1uF, but I suppose this shouldn't matter in this case.
Anyway I think the OPA2132 was a clear improvement and the bass sounded deeper and more controlled. Would be nice to test the expensive OPA627 too.
Edit: Oh, and I'm using +-15 VDC configuration from the power supply.
Yeah, I totally missed the fact that opa627 is a single channel device. There goes 20 €.
But the bright side is I learned my lesson and the amp itself is great!
When you have dual mono OPA627, you will see that sounds great.
So I have a Sparkolabs ss3602 discreet OPamp I bought to try in the Salas headphone amp. After a number of listening tests including the wife weighing end, we decided to stick with the original design using the AD823.
So swapped out the 823 for the SS3602 last night in the Pass DIY HP amp. To my ears an improvement. I am really enjoying the bipolar input of the SS over the Jfet opamp. I have ordered an OPA1642 to try.
Qudos to Wayne for a great sounding HP amp regardless of the opamp!
So swapped out the 823 for the SS3602 last night in the Pass DIY HP amp. To my ears an improvement. I am really enjoying the bipolar input of the SS over the Jfet opamp. I have ordered an OPA1642 to try.
Qudos to Wayne for a great sounding HP amp regardless of the opamp!
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Hi,
I ordered myself a couple of PCBs with the gerbers posted in #457.
I have a few boards left, if anyone is interested, drop me a PM. Since shipping costs are a major part of the overall cost, this will make the most sense for the European fellow DIYers.
@Wayne, thanks a lot for the ingenuity and effort that you put into this project, and the generosity to share it with the community. Can't wait to hear that one sing!
Best regards,
hallodeletue
I ordered myself a couple of PCBs with the gerbers posted in #457.
I have a few boards left, if anyone is interested, drop me a PM. Since shipping costs are a major part of the overall cost, this will make the most sense for the European fellow DIYers.
@Wayne, thanks a lot for the ingenuity and effort that you put into this project, and the generosity to share it with the community. Can't wait to hear that one sing!
Best regards,
hallodeletue
I considered that approach as well, but in the end I decided to roll my own boards instead
Thanks Wayne for the excellent design - I look forward to listening more over the next days/weeks
/U.
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