Can REW show Fs in an IB?

[Chrisbee]

Don't tell Thomas but I am still wrestling with the problem of deciding whether my IB driver's Fs is as claimed.

My response curves seem to show a trough at the claimed Fs.

Thomas, who is far wiser and vastly more learned than I, has dismissed this trough as coincidence. He may be right. Though interestingly, others claim to see a trough at Fs in their own IB's response.

It has occured to me that an IB should show a system resonance peak in the impedance curve close to Fs. Sadly there is no impedance button on REW's magnificently furnished dashboard.

So can REW prove (or disprove) Fs conclusively for an IB driver in some other way?

Given the lack of compression from such a large enclosure shouldn't Fs ~= Fc? (for any driver mounted in an IB)

Is there some clue to Fs or Fc hidden in the graphs available from an REW analysis?

Thankyou for your interest.

[DrWho]

Not sure, but I know this program can:
http://www.audua.com/

[Chrisbee]

Thanks, Mike. I'll take a look.

[JohnM]

In principle you can, you'll need the appropriate test jig though (per the info on the Audua site). You could measure the reference resistor response and save that as a cal file, then substitute your drive unit and remeasure. That will get you the shape of the curve although not properly scaled impedance values, that could be a feature for a future release if there's enough interest.

[Chrisbee]

Thankyou, John.

The test jig looks horribly complicated for a single test project simply to end my doubts about Fs.

I was hoping for a simpler solution to my problem.

[DrWho]

Impedance measurements would be very cool to implement into REW. You could probably outsource test jigs and sell them for a minor profit too. Distortion measurements would also be nice, and then I wouldn't need to use Audua

[JohnM]

Distortion plots are on my dev list, relatively straightforward to do with log swept sine measurements as the distortion harmonics are neatly grouped in negative time before the linear response.