The "Quad experiment" at Scalford 2015

[Barry]

The June issue of Hi-Fi World has a report of this year’s HiFi Wigwam show at Scalford. In an attic room there was a demonstration of an audio system called “Quad experiment”.

It comprised four equi-spaced Quad 57 electrostatic speakers turned through 90 degrees, so the nominally vertical panels were horizontal. A Class D power amplifier fed each speaker.

The really interesting aspect was that the signal for the left-hand channel was fed across the sound stage, to the three speakers on the right, with the signal being progressively attenuated and delayed. The signal for the right-hand channel was similarly fed across the sound stage, also progressively attenuated and delayed.

The show report claimed the imaging was “awesome” the bass was "strong" without any cabinet resonance; in fact the system was described as “stunning”.

The idea of sequentially feeding both the left and right signals to electrostatic elements using delay lines is not new. Peter Walker discussed it in his Wireless World article of 1955, and of course a similar idea was employed in the Quad 63 and in all later ESL designs. But this is the first I have heard of anyone trying out the idea using Quad 57s.

Did anyone visit the “Quad experiment”, and if you did what were your impressions? I really would like to know, as it is a scheme I would be interested in trying out for myself.

[Firebottle]

Hi Barry, I was there and it was stunning.

If you can try it out yourself I would, everything that has been said is correct.

Alan

[Barry]

Hi Alan,

That's reassuring to know. For me it would be a future project, since at the moment I do not have the room for four spaced 57s. But I could well move to somewhere larger where there was enough room.

I assume the time delay between speakers is simply the separation divided by the speed of sound, so assuming a 1.5m separation the delay would be something like 4.5ms. What do you think the attenuation between speakers would be, 6dB, or greater?

Regards

[Jimbo]

The June issue of Hi-Fi World has a report of this year’s HiFi Wigwam show at Scalford. In an attic room there was a demonstration of an audio system called “Quad experiment”.

It comprised four equi-spaced Quad 57 electrostatic speakers turned through 90 degrees, so the nominally vertical panels were horizontal. A Class D power amplifier fed each speaker.

The really interesting aspect was that the signal for the left-hand channel was fed across the sound stage, to the three speakers on the right, with the signal being progressively attenuated and delayed. The signal for the right-hand channel was similarly fed across the sound stage, also progressively attenuated and delayed.

The show report claimed the imaging was “awesome” the bass was "strong" without any cabinet resonance; in fact the system was described as “stunning”.

The idea of sequentially feeding both the left and right signals to electrostatic elements using delay lines is not new. Peter Walker discussed it in his Wireless World article of 1955, and of course a similar idea was employed in the Quad 63 and in all later ESL designs. But this is the first I have heard of anyone trying out the idea using Quad 57s.

Did anyone visit the “Quad experiment”, and if you did what were your impressions? I really would like to know, as it is a scheme I would be interested in trying out for myself.

Stacked Quads are an old favourite and are awesome but not heard them in the specific controlled way they were done at Scalford.

[Audio Advent]

How was the delay done? Delayed towards the centre or outwards?

From just thinking about it now, I wonder if the good sound was the equivalent of adding a synthetic but spacially natural reverb.

[Audio Al]

I could well move to somewhere larger where there was enough room.
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Wow Thats some upgrade

[Firebottle]

If you contacted the exhibitors of the Quad Experiment on the Wam I'm sure they would share the details to assist you in reproducing the set-up.

[Spectral Morn]

Pretty sure the late Peter Lindley of Lindley Audio did something like this back in the late 80s.



Regards Neil

[hificricketboy]

Looked a bit like this....

[ff1d1l]

Caught the quadquad system playing Ian Dury. Afraid it wasn't for me, though kudos to the constructors for trying something very different.