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QLS-1 Crossover Recap- experts opinions welcome-

I just finished the QLS-1 recap:)
Improvement right off the bat in the tweeter section. Highs are more pronounced and airy, in fact, all drivers seem to be more alive and not in a forward imposing manner.
They're still breaking in? Who knows. Well worth the effort in my humble opinion,,,,now on to the 2000a.
 
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It's a simple task but not particularly easy, however, well worth it.
I'm glad I changed out the "big caps" which I avoided on the Quantum 2s. Plus I'm happy I went with the suggestion of a better ClarityCap for the tweeters.
I'll undoubtedly revisit the Q2s crossover board:)
 
Have you had the chance to check all your tweeters ?
While I found 3 or 4 not working or barely working, I went in and checked them all.
What I found was at least 3 or 4 more with Marginally high readings. After repairing the Bad ones I went ahead and touched the others with the iron and was able to get them all very close to the same reading. This helped mine more than the new caps did.
 
All EMITs function on mine QLS-1 set however I havent done one-by-one with a meter for uniformity:)
I presume "3 or 4" EMITs not functioning would make for dull performance.
From what I've read, A. Nudell designed the QLS etal with the electrostat in mind "without the inherent problems" of a stat, that being less dynamic bass response.
I also believe electrostatic speakers are know to have rolled off highs, leaving them to be wonderful midrange performers...at the expense of unenthusiastic bass and laid back high end.
Point being 3 or 4" non-functioning tweets would be a problem. Glad you got yours going!
 
Having experienced a very perceptible improvement in sound by reinforcing and bracing a pair of Qbs, I had to make an attempt on my QLS-1s.
I added four 1-bys behind the woofer screwholes at 12, 3, 6 and 9 o'clock positions.
Also packed in the bottom portion of the cabinet where the crossover system resides with alot polyfill and left a cavity behind the woofer with just enough polyfill to line the sides of the cabinet walls.
Lastly, I applied ducting seal putty to the back of the baskets and around the magnet.
I believe I've made a sound improvement:yes:
 
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Very nice :)

I've had the exact same idea regadring the baskets, only difference is that I'll use Bitumen pads instead.
 
I"m going back in.
My Quantum 2 tweeter section puts out a pleasantly more forward display of airy highs and it seems as though all QLS-1 Emits are functioning well.
I'll probably opt for a combo of Dayton 1% polys/ foil bypass (2.5uf) caps on the "LOW" setting.
 
Another important question:)
Instead of removing my crossover board , again, is it feasable to temporarily(and carefully) add a bypass cap to the tweeter section to the back of the cabinet?

I was thinking a .47uf foil capacitor from the positve speaker terminal to the post of the tweeter x/over selector would add more capacitance and allow me to experiment with different caps.
 
tubed said:
Another important question:)
Instead of removing my crossover board , again, is it feasable to temporarily(and carefully) add a bypass cap to the tweeter section to the back of the cabinet?

I was thinking a .47uf foil capacitor from the positve speaker terminal to the post of the tweeter x/over selector would add more capacitance and allow me to experiment with different caps.
Click to expand...

I can't imagine why that wouldn't work. I'd be interested in hearing your results Tubed. (Sorry I didn't notice your post sooner!)
 
Hi Jim. It's very groovy to be able to add capacitance to the tweeter section without pulling apart the xover network.
 
I've been running the EMITs at 2.5uf all this time too. I've also been trying to wrap my brain around the actual crossover points for the EMITs and mid-domes, but I can't figure out what nominal impedance to use in a calculator.

Measured DC resistance of the front EMIT line is 4.3 ohms in the right channel. The mids measure 6.9 ohms.
If I use the DCR value a 2.5uf cap crosses at 14500Hz.
If I add the tweeter pot (4.3+5.0 ohms) a 2.5uf crosses at 6800Hz.

OTOH, if I assume a nominal 6 ohms for the EMIT line + the 5 ohm pot a 2.5uf crosses at 5800HZ.
But what if I switch in the rear EMIT? If it measures 6 ohms do I add it too? If I add it to the above (6+5+6 ohms) a 2.5uf crosses at 3700Hz.

But I have a feeling this is all wrong (thinking out loud here). Crossed at 3700Hz means that at 6db down (first order Butterworth filter) the EMITs are trying to handle 1850Hz. At 12db down that's 925Hz. At high volumes that would probably heat them up, plus that's well into the range of the mids according to the data sheet.

So my figures are all wrong. But what do we really know?
Are the crossover points shown of the data sheet at 6db down already? That would mean the EMITs are crossed at 8000Hz electrically (1 octave above 4000Hz).

Anyone know the capabilities of the EMITs? Ever seen a frequency graph or T/S parameters?

My head hurts!
That's why I'm interested in your tests!
 
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My head hurts just READING your last post.
Man most of what you just said was a flyover.:yes:
I'm just glad that guys like me can ask guys like you questions.
Guess that that's what makes AK the site that it is.
I know that I want to do my crossovers someday so I am watching with interest.
 
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I really have no idea what the impedance of a single QLS EMIT should be.
I didnt have to remove/repair any of my tweets to meter test.
I suppose if I ever "go back in" I'll isolate the tweeter section and test as a whole. It's either 8, 6.5, 4 or 3.2 ohms:).
 
tubed said:
I really have no idea what the impedance of a single QLS EMIT should be.
I didnt have to remove/repair any of my tweets to meter test.
I suppose if I ever "go back in" I'll isolate the tweeter section and test as a whole. It's either 8, 6.5, 4 or 3.2 ohms:).
Click to expand...

Testing the 8 front EMITs is as simple as pulling the blue and blue/black wires from the terminal strip and connecting a ohm meter to them.

I don't understand much, but I'm sure that the larger a value of cap you put in there, the lower the crossover frequency, no matter what the impedance or resistance is.

Since our ears are more sensitive to treble in the lower range, say 4000 ~ 8000Hz, the lower crossover point should combine the EMITs with the mid-domes for more output. The response may not be flat anymore though.

I'm sure these speakers were 'voiced' by ear anyway, so what sounds best to you is what counts.
 
Bucky Badger said:
My head hurts just READING your last post.
Man most of what you just said was a flyover.:yes:
I'm just glad that guys like me can ask guys like you questions.
Guess that that's what makes AK the site that it is.
I know that I want to do my crossovers someday so I am watching with interest.
Click to expand...

Glad you edited your post! I have to much free time to ponder this stuff. :scratch2:
The safe bet is to make sure all drivers and pots are working, then re-cap with the standard values. It made a big difference for mine. :thmbsp:
 
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