Ultra high performance headphone amplifier QRV09

[peranders]

Urban, now you can edit. I have approved the last changes.

 

[UrSv]

Thanks P-A.

With regards to the PPS caps not being available from Farnell, do you mean for the 2220 or in general? They seem to have plenty of PPS caps but not in 2220. Say for instance 1855059?

The answer about the coupling cap at the input: The footprint is for a 2220, a PPS Metallized Polyphenylene Sulfide cap from RIFA. The Farnell article number in my BOM goes to a 1210 cap with PEN dielectricum. Farnell hasn't got any PPS caps.

 

[peranders]

Right now I can't connect to Farnell but I'm open for suggestions. I'm after a good plastic SMD cap.

 

[vardenis]

Peranders,
are there any real world QRV09 or QRV07 measurements? This link http://www.sjostromaudio.com/hifi_files/qrv/qrv07_testreport/QRV07_HD545.htm seems to be dead.

 

[peranders]

Test Santa Cruz(tm) only SC No load Senn heisser HD545 10 ohms out 39 ohm load 10 ohms out
Frequency response (from 40 Hz to 15 kHz), dB: +0.04, -0.20 +0.05, -0.24 +0.19, -0.24 +0.05, -0.24
Noise level, dB (A): -80.3 -77.9 -77.7 -80.6
Dynamic range, dB (A): 80.0 77.6 77.1 80.3
THD, %: 0.0070 0.0065 0.0065 0.0058
IMD, %: 0.050 0.069 0.069 0.052
Stereo crosstalk, dB: -78.8 -75.3 -72.0 -77.7

The data is better than the used soundcard. By accident the pictures have gotten corrupt. No measurement on the QRV09 yet.

 

[peranders]

Thanks P-A.

With regards to the PPS caps not being available from Farnell, do you mean for the 2220 or in general? They seem to have plenty of PPS caps but not in 2220. Say for instance 1855059?

This might work and a smaller size doesn't matter.

 

[cobretti]

Test Santa Cruz(tm) only SC No load Senn heisser HD545 10 ohms out 39 ohm load 10 ohms out
Frequency response (from 40 Hz to 15 kHz), dB: +0.04, -0.20 +0.05, -0.24 +0.19, -0.24 +0.05, -0.24
Noise level, dB (A): -80.3 -77.9 -77.7 -80.6
Dynamic range, dB (A): 80.0 77.6 77.1 80.3
THD, %: 0.0070 0.0065 0.0065 0.0058
IMD, %: 0.050 0.069 0.069 0.052
Stereo crosstalk, dB: -78.8 -75.3 -72.0 -77.7

The data is better than the used soundcard. By accident the pictures have gotten corrupt. No measurement on the QRV09 yet.

What equipment-soundcard was used to acquire this data(measurements)?

 

[MrSlim]

Peranders: is the price of the boards still contingent on getting commitment for 100?

 

[peranders]

What equipment-soundcard was used to acquire this data(measurements)?

See my post. It says (Turtle Beach) Santa Cruz.

 

[peranders]

Peranders: is the price of the boards still contingent on getting commitment for 100?

Possibly a slight adjustment up, not much.

 

[Salas]

Post #26 pics removed on poster's request for showing some wrong wiring. You may post again the correct ones.

 

[UrSv]

I have ordered 2 pcs of AD8610 but I have a pair of OPA627s as well. Would there be any reason to use those instead of the AD8610s or any reason NOT to use them? In short, which would would be preferable? The specs suggest it would not be too bad..

 

[peranders]

According to me as we swedes say "Aftonbladet or Expressen".*) Both opamps are good in this application.

*) The two biggest newpapers in Sweden.

 

[UrSv]

Hmm, somehow I knew that answer was coming

 

[peranders]

Urban, you could put the question at head-fi.org if you want a precision answer from the real experts.

 

[UrSv]

I went for the AD8610s. As I wrote in the GB thread I realized that I might need glasses in the near future but it was still not too bad. After a few components I got the hang of it although some were a bit fiddly indeed.

I'm now waiting for the transformers from Elfa as I wanted black Hahn transformers rather than the red Myrra. Everything else I got from Farnell.

Also, the search for a chassis has begun...

 

[peranders]

The Myrra transformers are very brown actually.

You may check out Hammond cases.

 

[UrSv]

Can't say I really like Hammond. They haven't really got anything that looks OK.

I'll probably go for the cheaper and time saving option of this:

 

[cobretti]

P-A
I suggest the next PCB comes with option to change op-amps as every op.amp sounds different. Probably a DIP socket. People might appreciate the option to experiment with the sound. I have a bucket of various op.amps I would like to try, there is no way on this PCB.

 

[peranders]

This will hardly happen, I'm afraid. Using a socket itself may cause problems in particular when you are trying fast opamps and in many cases you will get colourations just because you are using a socket, not using different opamps. The "sound" between good opamps is less different than you'll think. A good pcb does half the job here.