Wallin II / SW impedance calib problem

[ultrachrome]

I'm having a heck of time peforming the impedance calibration with my jig.

My impedance curves for my drivers never dip below 12 ohms for what should be 7-8 ohm drivers.

My jig measured out correctly after I built it but I notice that when I have J2 and J3 connected to my sound card (M-Audio Transit USB) and set the jig to 16 or 4 ohm calibration mode that BP3-BP4 measure 31 and 8 ohm, respectively. Is that normal?

My other problem is that the calibration process says that I appear to have an open connection.

I've tried connecting it to the laptop's internal sound card and have tried different cables but I still keep getting the same error message.

Any ideas?

 

[noodle_snacks]

Have you gone through the process of setting the levels using loop record mode and a sine wave? I found the peaks of the waveform clipping were giving me some trouble in impedance measurements.

 

[Vikash]

My jig measured out correctly after I built it but I notice that when I have J2 and J3 connected to my sound card (M-Audio Transit USB) and set the jig to 16 or 4 ohm calibration mode that BP3-BP4 measure 31 and 8 ohm, respectively. Is that normal?

That's not normal. I suggest going through the jig electrical checkout first.

 

[ultrachrome]

Looks like it's a problem with my laptop. In the IMPCAL16 mode, the BP3-BP4 resistance measures 32R when plugged into the Transit and 64 when plugged into the laptop's line in.

Did the Wallin checkout a second time and found no problem.

Took the jig downstairs to my desktop line in and IMPCAL16 meausures 16R just like it's supposed to.

Crap. Now I need to drag my desktop upstairs. Girlfriend is not going to like that.

 

[ultrachrome]

****

Wow, that auto-censor is touchy. If you make that word plural, it's a dice game.

 

[wintermute]

Did you try measuring again after doing the first calibration? sometimes if the calibration is out it will take a few goes to get a proper reading.

The other thing that might help is working out the impedance of your laptops sound card, and put that in instead of the default.

Tony.

 

[ultrachrome]

I tried using my desktop machine with its cheesy built-in Realtek AC97 sound card and it calibrates fine and I now have accurate looking impedance plots of my tweeter and midrange.