WT3:Calibration problems? Change your...

[Interlochen2]

..Alligator clips. My new unit had miserable clips with springs so wimpy they'd barely close the clip after a few uses.

Also, from what I could barely see in there, the solder job was also miserable. During the shorted calibration procedure, I kept getting the warning box - forget what it said. And 1 k ohm calibrations were bizarre.

So I cut the lead length to half the original (inductance) and properly soldered on some stout clips. This completely solved the calibration problems and must think it improved measurement accuracy.
Dave

[billfitzmaurice]

Re: WT3:Calibration problems? Change your...

Mine came through with a cold solder joint of the connection of one of the leads inside the unit. Before I fixed it the reading of lead impedance was a few hundred ohms.

[Interlochen2]

Re: WT3:Calibration problems? Change your...

Thanks Bill,
I'll check my internal connections as well.
Dave

[ReissM]

Re: WT3:Calibration problems? Change your...

The manual warns of waiting for a little while when you first plug it in. I have found that no matter how long I wait, the first calibration always fails. The next one works like a charm.

Maybe there's some type of initialization or "initial conditions" involving the software's inner workings... which gets straightened out after the first pass??? Software programmers see this kind of thing all the time.

As for the poor workmanship issues, well that's poor Quality Control and should have never happened.

I do love this WT3. It was very tedious and time consuming doing this type of impedance sweep 15 years ago. Now it's about 2 seconds and very reliable.

I also love the capability to measure the T/S parameters. About 10 years ago, I tried working through all the various tests and measurements to derive the T/S parms the "old fashioned way". I spent the better part of a full day and ended up with results that I didn't have confidence in. This system makes it so simple and then I'm on to the next design step!!! Bravo.

[arlis_1957@yahoo.com]

Re: WT3:Calibration problems? Change your...

my shorted leads test always claims to be over 1ohm, will continue to use previous setting.
thanks for the info.

[Whitneyville1]

Re: WT3:Calibration problems? Change your...

QC issues happen on million dollar+ Bugati's, and on $30 million dollar F-1 cars, and on military aircraft ain't nobody ever gonna know how much THEY cost! (I've fixed 'em!) For $3000 each for a WT-3, maybe we could resurrect Fairchild Instruments, but I doubt it.;)

[Interlochen2]

Re: WT3:Calibration problems? Change your...

I think the WT3 is great. A ton of power for the money. I have no other complaints.

ReissM: I've never had that 1st test failure problem.
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[Tentative thought, awaiting my mentors approval Edit - My mentor was unable to disprove my theory. Still, this does not mean it's necessarily correct. So I'm still open to obliteration of my theory.]

I've been doing some thinking and basic physics. It really looks like the driver should be tested when mounted in the same orientation it will be in when finally mounted in your enclosure.

For example: With the SS 18W8531g, I get almost double the Vas when mounted vertically vs. horizontally. ~50 liters, which agrees with Zaph and Scanspeak.

(I'm completely open to correction on the following physics.)

Vertical mount: a = F/M ....Horizontal: a = (F-mg)/m.

This is highly simplified, ignoring air load, suspension effects, etc.
I've noticed other guys like me getting extremely low Vas numbers. Vertical mounting solved it.
Dave