Acoustat 2+2 with a single Spectra panel

[john65b]

Hey all, Looking to modify a just acquired pair of 2+2 and drop in a single Spectra panel in the top inner slots.

I cannot remember if it was ill-advised to run a SPectra panel with the three wire MK-121 interface, or the old 3 wire panels to a five wire Spectra interface. I don't see how it would matter, as you would just need to make a few modifications and either case should work...

Anyway, for my new 2+2, I can wire the normal three SPectra panel wires (two stator wires and bias), and the remaining two stator wires to a 350k resistor back to the other stators wires (for the delay effect - just like it is set up in the SPectra interface), or just wire these stator pairs together like a 3 wire...

What am I looking to accomplish? Better HF output and dispersion at the expense of giving up a little LF on that single panel.

All other interface changes would be standard fare - additional ladder rung Diode/cap for higher bias, C-Mod, etc...

Anyone?

 

[AcoustatAnswerMan]

Hmmm...unless I'm missing something in your explanation, I don't think you will accomplish what you're trying to do. Driving half the Spectra panel full range equals no change at all. Driving the other half through a resistor will roll-off the top end, and actually reduce the HF output of the speaker. Also keep in mind that the time delay is for use with panels arranged in a flat plane. The 2+2's panels are arranged in an arc.

But to answer your basic question, a Spectra panel can be used as a replacement for an older 3-wire or 5-wire panel. For either configuration, just connect the two front (white) wires together, and connect the two rear (blue) wires together, and connect to the appropriate interface terminals.

Spectra panels were produced only in the 9" width, so Spectra panels cannot be used to replace the 8" panels used in the center positions of Models 3 and 4.

 

[john65b]

OK, the resistors were to match the spectra design, and would do very little - I agree - I forgot that this was also accomplished on 2+2 by arc arrangement...

But the Spectra panels had better coating, and 1/2 the width (sectioned in two) which are both conducive for better HF propagation, correct?

 

[AcoustatAnswerMan]

OK, the resistors were to match the spectra design, and would do very little - I agree - I forgot that this was also accomplished on 2+2 by arc arrangement...

But the Spectra panels had better coating, and 1/2 the width (sectioned in two) which are both conducive for better HF propagation, correct?

True that the Spectra panels used an improved coating, which Acoustat starting using several years BEFORE Spectra was introduced. Improved-coating panels can be identified by a bias wire that is yellow w/red spiral stripe. Original-coating panels used a bias wire in solid red, or white with a red spiral stripe. The improved coating allowed a considerable increase in dynamics. No change in HF was attributed to the change in coating.

The splitting of the Spectra panel, per se, had no effect on HF behavior. What makes the Spectra different (and better) is HOW the panels are driven. This can be achieved only through a proper Spectra interface system. In other words, you can't make an older model into a Spectra, or even into a 'sorta'-Spectra. Among other things, the equalization of the Spectra system is quite different than the MK-121 series.

 

[tyu]

john did you see this..............if you add more res....you well get more topend

this is a type of Air mod...you dont need the other cap are swetch.....i move away from the 1+1s an the 2+2 type setup....the top an bottem reforsment....gave better bass...but to me rool off the topend...to much....but this may be a fix
in my room an setup about 15" off the floor to the bottem of the panels give the best bal....well to day anyway..hehe
As with so minny things with ESL..... thanks too Bolserst for his Art..