Very true! (Although those who make the discrete opamps would likely disagree...)
This circuit was designed with an IC Opamp.
No. It's unbalanced the whole way through the signal path.
I've used and heard IC input stages before and they can sound quite good! I'm sure Wayne did a good job and I might just build it as I need a second HP amp. It would be nice too as a preamp for the ACA! Nice PASSDIY desktop system!
Hmmm...I'm a little confused.
Is this amplifier Wayne's design, Jam Somasundram's design or a combined effort of both?
I've never heard of Mr. Somasundram before. Looks like he was with Cary Audio a couple of years ago.
This article states that Jam is "the engineering brains behind Pass Labs' forthcoming headphone amplifier".
Pass Labs debut INT-60 integrated, headphone amp at CES 2015 | DAR
Is this amplifier Wayne's design, Jam Somasundram's design or a combined effort of both?
I've never heard of Mr. Somasundram before. Looks like he was with Cary Audio a couple of years ago.
This article states that Jam is "the engineering brains behind Pass Labs' forthcoming headphone amplifier".
Pass Labs debut INT-60 integrated, headphone amp at CES 2015 | DAR
Wayne's.
This has little in common with the Pass Labs offering. That's a significantly more complicated design, and wouldn't make a good DIY project.
This has little in common with the Pass Labs offering. That's a significantly more complicated design, and wouldn't make a good DIY project.
Yes, I would suspect that the PASS LABS HP amp has much better power supply regulation and probably a discrete circuit from input to output.
Possibly moar power too!
This DIY version looks to have been designed to provide great sound whilst being quite easy to build (no need for bias adjustment, all in one board).
6L6, I don't want to be in your shoes - advertising OpAmp + source follower as a "new headamp", you'll need a top marketing pro to get you out of that one... 😀
Well it's a new design from Wayne, and the optocoupler bias scheme might be novel, but the whole thing as a concept is quite old indeed! A proven design though so it will certainly sound good.
Of course.
Although it would probably make more sense to set it to unity gain, as your source would have to drive the pot and the outputs.
Although it would probably make more sense to set it to unity gain, as your source would have to drive the pot and the outputs.
LOL...LOL!
It isn't hard to figure out what Zen and Juma think about this design.
I'm hoping it'll sound better than the Lehmann clones.
There are many good opamps around these days.
If you wish to have FET input, try OPA1642 or LT1169.
If you want to have FETs through out, check out :
https://www.passdiy.com/pdf/diyopamp.pdf
http://www.diyaudio.com/forums/pass-labs/120445-pass-discrete-opamp-dip-8-package.html
Then you will have a Pass design through and through.
And you will have enough DIY challenges to trim DC offset and handle thermal drift.
If I were to redo it today, there are actually many more choices for SOT23 JFETs than 2008.
For the input diff pair, I would use 2SK2145(GR or BL), ideally made for the task.
For the other NJFETs including current source, I would use 2SK209BL.
The only exception is the diff pair CCS, which should be 2SK209GR.
For the P channel device, I might even consider PBMFJ177 or MMBFJ271.
All available from Mouser, e.g.
Still not good enough ?
Then you can always build a F5 with 2SK2013/2SJ313 at 100mA bias.
🙂
Patrick
If you wish to have FET input, try OPA1642 or LT1169.
If you want to have FETs through out, check out :
https://www.passdiy.com/pdf/diyopamp.pdf
http://www.diyaudio.com/forums/pass-labs/120445-pass-discrete-opamp-dip-8-package.html
Then you will have a Pass design through and through.
And you will have enough DIY challenges to trim DC offset and handle thermal drift.
If I were to redo it today, there are actually many more choices for SOT23 JFETs than 2008.
For the input diff pair, I would use 2SK2145(GR or BL), ideally made for the task.
For the other NJFETs including current source, I would use 2SK209BL.
The only exception is the diff pair CCS, which should be 2SK209GR.
For the P channel device, I might even consider PBMFJ177 or MMBFJ271.
All available from Mouser, e.g.
Still not good enough ?
Then you can always build a F5 with 2SK2013/2SJ313 at 100mA bias.
🙂
Patrick
LOL...LOL!
It isn't hard to figure out what Zen and Juma think about this design.
I'm hoping it'll sound better than the Lehmann clones.
what I said there exactly - was a comment about bias scheme - another breadcrumb for Greedy Boyz ........... not comment on preamp generally
and speaking of a preamp generally - I have no intention to dispute value of a gift to DIY community ..........