abbey road d enfer

Re: Audio test interface
« Reply #20 on: May 07, 2013, 03:34:39 AM »
Nice !

Would you eventually make the pcb available ?

This interface + the Q400 is more than enough for my needs.

Waiting for your report with the AP testing.
Yes I would. And probably also the case and front panel. I'm expecting metalwork prototypes any day.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.


abbey road d enfer

Re: Audio test interface
« Reply #21 on: May 08, 2013, 01:20:29 PM »
I've submitted the ATI to the AP. Performance is up to expectations:
Frequency response <5Hz-200+kHz BW (+0,-0.5dB)
EIN of the measurement section better than [email protected] gain, [email protected] gain (22Hz-22kHz BW)
THD+N better than 0.0035% from 20Hz to 20kHz (measurement BW 30kHz)
Residual noise of generator section -108dBu @ 0dB attenuation (22Hz-22kHz BW)
The only performance point I had not been capable of predicting was the real capability of the circuit to drive unbalanced sources with the attenuator in-circuit. Unlike a xfmr-output, the 1646 has a finite CM impedance, which alters the level when on eof the legs is shorted to ground.
I have found this difference to be less than 0.2dB for 50r and 150r output Z, and less than 0.5dB for 600r output Z.
It's not a big problem, but still one has to keep in mind.
Overall I'm very pleased with the results, now I should receive my Q400 next week, as well as the metalwork.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Samuel Groner

    Zürich, Switzerland
  • Posts: 2935
Re: Audio test interface
« Reply #22 on: May 11, 2013, 11:24:12 AM »
The EIN should be better at 20 dB gain than at unity? At what level is 0.0035% THD+N, and is it distortion or noise?

Samuel

JohnRoberts

Re: Audio test interface
« Reply #23 on: May 11, 2013, 11:32:33 AM »
I just ASSumed he was talking output not input noise. -108 @ 20dB gain vs -103 @ unity seems reasonable for the input side.

JR
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

abbey road d enfer

Re: Audio test interface
« Reply #24 on: May 11, 2013, 12:17:33 PM »
I just ASSumed he was talking output not input noise. -108 @ 20dB gain vs -103 @ unity seems reasonable for the input side.

JR
Yes, sorry. EIN is [email protected] gain
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

abbey road d enfer

Re: Audio test interface
« Reply #25 on: May 11, 2013, 12:25:16 PM »
At what level is 0.0035% THD+N, and is it distortion or noise?

Samuel
I had measured at 20dBu output in order to see some distortion. At 0dBu there's nearly as much noise than THD.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

RodrigoRocha.RJ

Re: Audio test interface
« Reply #26 on: October 31, 2013, 05:28:40 PM »
How is the development of the interface?
Any changes in the project?

abbey road d enfer

Re: Audio test interface New
« Reply #27 on: October 31, 2013, 06:45:00 PM »
How is the development of the interface?
Any changes in the project?
It's finished. I have put it in operation at the works, where it's used for basic measurements, awaiting development of specific plug-ins.
I haven't made any plans for selling it. If enough are interested, I could have a batch of PCB's made. I could also have a batch of front panels made. Cost of PCB's would be about £50 if I have enough orders for a batch of 10.
If that becomes a reality, I would have to start a new thread in the Black Market.
« Last Edit: October 31, 2013, 06:51:27 PM by abbey road d enfer »
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.


 

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