Re-Jigging the jig: Speaker testing device for Arta, Speaker Workshop & HOLMImpulse

[soongsc]

This thread is interesting, I think I'll stick with it more.
Originally I had thought about it, but I was concerned about noise. Especially the power amp section against the mic preamp. I was also wondering how the mic cable capacitance would effect mic performance. I started out with cheap plasic chassis for everything, and now gradually switching to metal chassis.
Below is something close to what I currently use as a jig design.
Normally, I would assume 3V rms for max SC input and output unless I know the specs on the sound card. This seems to have worked with many computers.
The input attenuator so that control of how much driver to the speaker is provided.
The output attenuator assures that no matter what level of power you select, the SC input is never overloaded so as to protect the SC.

[454Casull]

hoping for a response

[soongsc]

Originally posted by soongsc
This thread is interesting, I think I'll stick with it more.
Originally I had thought about it, but I was concerned about noise. Especially the power amp section against the mic preamp. I was also wondering how the mic cable capacitance would effect mic performance. I started out with cheap plasic chassis for everything, and now gradually switching to metal chassis.
Below is something close to what I currently use as a jig design.
Normally, I would assume 3V rms for max SC input and output unless I know the specs on the sound card. This seems to have worked with many computers.
The input attenuator so that control of how much driver to the speaker is provided.
The output attenuator assures that no matter what level of power you select, the SC input is never overloaded so as to protect the SC.

forgot the pic.

[soongsc]

and panel

[MJL21193]

Originally posted by 454Casull
MJL, the - output from the amp in your schematic goes to ground. What if the - of the amp isn't at the same potential as its own ground (signal, power)?

Also, when jumping BP3_4 with a calibration resistor, do all the other connections need to be disconnected?

Hi 454,
Sorry for the delay.
I used the ground symbol in the schematic as a handy way to show things and to simplify. In my version of this jig, all of the grounds do tie together, but input ground to the amp has a 10 ohm resistor for isolation - see revised schematic below.

When I use the calibration resistors, nothing gets disconnected, I just switch to "direct" and follow the calibration procedure.
Hope that helps.

[454Casull]

Oy, thanks for the response. I decided to go with Claudio's cables, though.

I ran into a problem doing his volume setup. When I output a sine signal, the input windows show square waves. I thought it might be severe clipping, but when I reduce either the output or the input volumes, beyond a certain point, the square waves suddenly disappear, and nothing shows up on the inputs (except some noise...?)

Did I really screw up the cables, or is my sound card bad?

[MJL21193]

What sound card are you using?
Are you using Speaker Workshop or Arta? SW can be a real beotch to setup, I've logged many hours with that program just to get it working properly.

[454Casull]

Speaker Workshop

I'm using the onboard sound card.

[MJL21193]

I've used onboard sound before without problems. Did you run the duplex test in SW? It'll tell if the sound card can record and play simultaneously.

What chipset? Realtek? Intel? VIA?...

[454Casull]

Yes, I did use sound card wizard to check and it gave me passing results.

It's a Realtek HD something or other.