QRV-08 Headphone amp with current feedback and super ....

[peranders]

The  subject I wanted to write was:
QRV-08 Headphone amp with current feedback and with a double power supply equipted with four super regulators... but this was too long.


This weekend I have made everything ready for ordering pcb's for my QRV-06 together with a double power supply which contains everything including super regulators and then is QRV-08.

The QRV-06 has worked quite well but I forgot that the input current is not small so I have added some input bias network. I have also added an optional DC servo so expected output offset voltage wil not be more than 80 uV.

... and yes, almost every part are SMD. This design is pretty easy to build but it requires patience and good order of things and also a stategy of the building process be troubleshooting is a bit harder than with regular parts.

Only a very few have dared to build a QRV-06 and "digi01" is one of them. All in all 12 are built including my prototype.

No text is ready yet but the schematics, pcb layout and partlists are uploaded.
http://sjostromaudio.com/_unsql/hifi/qrv08/downloads_qrv08.html

[peranders]

I have soldered 90% now....  :D

[Sigurd Ruschkowski]

Will be very interesting to hear about the sound quality!


Sigurd

[peranders]

The amp is working now,  :D  A very small test says that I should be pleased. More details will come later.

[Sigurd Ruschkowski]

Good work!

Anything one should think about when assembling the headphone amp?


Maybe it is time to get some reference headphones, P-A?




Sigurd

[peranders]

A snapshot of the pcb. Pictures with better quality will come. (the same camera but better lighting)

[Sigurd Ruschkowski]

Looks awesome!
I like those many caps.

Could you take some close-ups, too?


Sigurd

A snapshot of the pcb. Pictures with better quality will come. (the same camera but better lighting)

[peranders]

I have had a long listening session and I must say that I'm pleased, very pleased! It adds nothings, it subtracts nothing.  :D

[peranders]

To be true only a very very few people can detect properties between well designed amps. I am very skeptical to opinions like "bright", "bass slam", "sound stage" etc. etc. Those people normally don't have any reference gear besides the amp in test so they are listening to the whole chain and have no idea how the amp itself sounds like.

I have listened to PPA, not much though, and it sounds good, equally good as mine. When I listen to my 7 different amps I can't detect any significant difference but since I have designed them it's a certain feeling for each of them.

When it comes to QRV08 people that have listened to it have loved it. Noone yet has built one but two may be built in the fall. You should not build this amp as your first SMD project unless you have a very good selfconfidence AND are handy.... but if you do deside to build it you have one of the most advanced headphone amp in the whole market, DIY and commercially.... says I  :D No amp in the whole world has ever had 4 super regulators and I'll doubt even 2.

I can say so much that I'm very pleased with the design and I regard this the highest, the best I ever have done. It was very fun to do because each part were already debugged. The amp is a developed version of QRV-06 and the power supply is JSR03 and JSR05 converted to SMD parts.

All amps of mine can drive any headphone you like to painful high levels so you don't have to worry about your Grados or whatever.

[peranders]

You have to get all parts yourself except for those I have for sale. The total cost can vary a lot so I don't say any prices. It's not a low price project but not extremely expensive either.

The total height is approx. 25 mm plus a few mm at the solderside.

You don't have to match or trim anything. The only thing you have to adjust is the input bias with the trimport, besides that nothing. I soldered all parts into place except for the DC servo opamp and the R3, E3 (will turn off the amp). I got the right voltage, tested also to load the regulators, then I mounted R3, E3, .... boom it worked! The challenge is of course to place the right part in the right place.....