Quad ESL treble panel additional test before sending to service

[stokessd]

stokessd
looking at the treble membrane, do you stretch the membrane with higher tensil force "sideways" than on the length?
If you look on the picture you see that the membrane itself bends in two dimensions.
Do you use different force in X versus Y?

You are looking at the dust cover in that picture, which is intentionally pulled in with four felt washered fasteners. That can be seen here:

So the tension doesn't really come into play, it's a mechanical warping of the dust cover.


Sheldon

 

[jzagaja]

There is something I don't understand. Putting ear near good treble panel I hear voices clearly in front. In repaired panel it is hard to tell. First check with Chesky test CD stereo imaging was ok. I think I must check with microphone and impedance what's going on.

 

[jzagaja]

With repaired panel output at 2kHz is -19dB compared to left speaker - see RTA. I will check swapping treble panels.

 

[stokessd]

Do you have the phasing wrong? is the center section wired out of phase to the two side sections?

I always mark the rear wires with a black band so it's easy to not get the phasing wrong when attaching to the crossover, does One Thing do something similar?

Sheldon

 

[jzagaja]

It's custom build (not mine) tweeter panel with two blue and two black wires. Three bass panels stacked vertically with new cascades - must check internal wiring.

 

[jzagaja]

I compared tweeter panel wiring with good speaker and found middle section was swapped (front to back). But this don't change SPL level.

 

[jzagaja]

One Thing Audio asked for EHT picture. After seeing their unit, they said that will send another panel because last received (above) is not up to spec.

 

[jzagaja]

New panel from OTA is now ok. In spare time will try measure SPL/imp.