Self's "5532 Low Noise Unity Gain Balanced Input Stage"

[sgrossklass]

Looks like measurement grade 😀 onboard audio, or something not very far from it... the 0.05-ish dB periodic ripple is telling. Good enough, anyway.

I think the idea would be comparing a straight loopback vs. a detour over -80 dB --> LNA. (The ground loop may need to be taken care of.) At least I'd expect much better accuracy from that when compared to using the signal generator as a source. You should have 20 dB of difference, pretty much all the rest is your gain error.

 

[SGK]

Thx. Let's continue this part of the conversation in the Groner measurement amp thread as it is more appropriate place.

 

[tER299]

SGK, do you by any chance have the dimensions of the input stage? Given that you seem to have had the some holes drilled (#146).
http://www.diyaudio.com/forums/soli...ty-gain-balanced-input-stage-post4807633.html

 

[SGK]

Of my input board? 65 x 50mm. The mount holes are indented 5mm (each dimension) Let me know if you need the centres for the placement of the connectors.

 

[stocktrader200]

Dewarth had it right earlier. Just use a THAT low noise preamp set to 120 and crush this multi chips performance.

 

[SGK]

If you want the noise go ahead.

 

[tER299]

Looking through this thread, I noticed this:

The lowest result was -84.41dBV @ 8kHz while the highest was -80.76 @ 400Hz. The average was -82.00 dBV.

I just remember Douglas Self's capacitor distortion test, and some of the (film) caps peaked at 400Hz. So, I think a mild improvement might be accomplished by using different capacitors. Any opinions on this?

 

[vlpy]

Anyone tried OPA1612 instead of LM4562?

 

[SGK]

LME49740 replacement - Audio forum - Audio - TI E2E support forums

https://www.ti.com/product/OPA1604

Not tested etc but found the reference and thought it useful to post it here