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QLS-1 Crossover Recap- experts opinions welcome-

T

tubed

Lunatic Member
I've finally succumbed to the the notion that I must recap my QLS-1 crossover network:)
The pic and Infinity diagram shows the use of three caps for the tweeter, one 1.75uf, a 2.5uf and two 2.5uf in series.
Why would Infinity choose two in series instead of on 1.5uf capacitor???
I also assume the two caps in series are wired to the "mid" tweeter level setting?

I guess I'll settle for a combination of Dayton metalized, metalized 1%, film/foil polypropylene, and Theta foil/tin bypass on the tweeter.

http://www.infinity-classics.de/mod...ource-QLS-1/QLS_1_crossover_schematics_01.jpg

Oh yeah. Boy were those covers were a bitch to remove from these particular pots:sigh:
 
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two 2.5uF in parallel gives 1.25uF, which would be the high setting.

i think you've got the right idea with the cap selection. i don't know about other guys, but i usually employed the low or mid XO point, so you might even think about picking one XO point you expect to use most and putting in even better caps there (such as ClarityCap SA).
 
Thanks for the suggestion.
Is that using the ClarityCapSAs without bypass caps?
I only listened to the speaker with the tweeter switch set to "MED"(1.75uf) how did you like the sound with the switch set to "LOW"(2.5uf)? I know I wouldnt want the tweeter crossed over any higher. There's a nice 2.2 ClarityCapSA at Madisound :)
 
tubed said:
I've finally succumbed to the the notion that I must recap my QLS-1 crossover network:)
The pic and Infinity diagram shows the use of three caps for the tweeter, one 1.75uf, a 2.5uf and two 2.5uf in series.
Why would Infinity choose two in series instead of on 1.5uf capacitor???
I also assume the two caps in series are wired to the "mid" tweeter level setting?

I guess I'll settle for a combination of Dayton metalized, metalized 1%, film/foil polypropylene, and Theta foil/tin bypass on the tweeter.

http://www.infinity-classics.de/mod...ource-QLS-1/QLS_1_crossover_schematics_01.jpg

Oh yeah. Boy were those covers were a bitch to remove from these particular pots:sigh:
Click to expand...

Tubed my caps should be in by tomorrow and I will be starting my recap. I ordered all the tweeter caps but have decided Im gonna only use the middle set wich are a 1uf and a .68uf=1.68uf to save space since I only use the middle position for the tweeters. I may even drop that position switch alltogether. Im curious what kind of pots those are in your pic, they look different than the ones in mine.
Here are the caps Im going to use for the tweeters. http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=027-410 and http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=027-408

By the way the tweeters use a (1.25uf) (1.75) (2.5uf) cap values. Take a look at this http://www.infinity-classics.de/technik/manuals/Quantum_Line_Source_1_technical_sheet.pdf
 
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jt45 said:
Tubed my caps should be in by tomorrow and I will be starting my recap. I ordered all the tweeter caps but have decided Im gonna only use the middle set wich are a 1uf and a .68uf=1.68uf to save space since I only use the middle position for the tweeters. I may even drop that position switch alltogether. Im curious what kind of pots those are in your pic, they look different than the ones in mine.
Here are the caps Im going to use for the tweeters. http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=027-410 and http://www.parts-express.com/pe/pshowdetl.cfm?PartNumber=027-408

By the way the tweeters use a (1.25uf) (1.75) (2.5uf) cap values. Take a look at this http://www.infinity-classics.de/technik/manuals/Quantum_Line_Source_1_technical_sheet.pdf
Click to expand...

The diagram linked in my first post most closely resembles my QLS crossover network with the 2,5uf caps in series)1.25).
I agree with using the "MED" setting although I'll replace the caps in the "High" and "Low" but try utilizing higher quality cap(s) for the "Med" setting...perhaps a 1.5 ClaritySA with a good .22 bypass capacitor.

If I were you I'd install A Dayton 1.5uf 1% metalized cap(027-212), finished off with Dayton .22 foil/tin bypass cap(027-454) or better. My .01 cents:)
 
Here's a couple before/after pics of my QLS-1 xover network in truly dire need of restoral.
I believe the Callins caps on the woofers and mid were leaking and very close to not working.
I replaced the electrolytics with Bennic capacitors, two 500uf plus a 100uf for the 1100 value and a 1000uf and two 200uf caps for the 1400 value
I'm going with a single cap on the tweeter, a 1.8 ClarityCap SA. I should see a definite improvement...still waiting to receive a 40uf Dayton metallized and combo of a Dayton metallized 12/ 1.5 metalized 1% for the midbass and midrange, respectively.

Madisound was very quick with their delivery.
 
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if it's still possible, it's not a bad idea to rearrange the inductors so they are as far apart as possible. that will help you minimize magnetic cross-coupling between the two woofer coils and the midbass, and this will give you cleaner midbass (whether or not it would always be audibly better is debatable, but it's theoretically a very good idea).
 
cdfac said:
if it's still possible, it's not a bad idea to rearrange the inductors so they are as far apart as possible. that will help you minimize magnetic cross-coupling between the two woofer coils and the midbass, and this will give you cleaner midbass (whether or not it would always be audibly better is debatable, but it's theoretically a very good idea).
Click to expand...

Will do!
I'll try to situate a couple coils at the corners if possible...where's those Daytons?:)
 
Do you have a DMM that can read capacitance? When I recapped my Quantum 3's and RS-IIIa's, I measured those original can caps and they were way off. I ordered Bennics for the low side, as you did, with the same values as the original caps. I had a 1000uf and 200uf in parallel for attaining the original value but, when measured with my Fluke, they read around 1480uf or so. I took out the 1000uf and it measured around 1150uf by itself so I removed the 200uf (which measured around 230uf) and eventually dropped in a 40uf Bennic that measured around 50uf. I don't know if I can "audibly" hear the difference in the changes, but those Bennic caps, being basic electrolytics, were definitely out there on measured versus spec rating. That's about a 15% tolerance. Pretty out there.
 
avguytx said:
Do you have a DMM that can read capacitance? When I recapped my Quantum 3's and RS-IIIa's, I measured those original can caps and they were way off. I ordered Bennics for the low side, as you did, with the same values as the original caps. I had a 1000uf and 200uf in parallel for attaining the original value but, when measured with my Fluke, they read around 1480uf or so. I took out the 1000uf and it measured around 1150uf by itself so I removed the 200uf (which measured around 230uf) and eventually dropped in a 40uf Bennic that measured around 50uf. I don't know if I can "audibly" hear the difference in the changes, but those Bennic caps, being basic electrolytics, were definitely out there on measured versus spec rating. That's about a 15% tolerance. Pretty out there.
Click to expand...

I don't have a capacitance meter.
I don't want to second guess the reliability of the +/-10% Bennics, or any of the other caps I've purchased. When installed if the bass sounds off I'd be prone to obtain a meter:)
 
Bummer.
My capacitors from Parts Express arrived this morning in an empty torn paper package.
Madisound sent my Bennics and ClarityCaps in a box and arrived very quickly.
PE will send out a new order, hopefully promtly and in a better packaging.
 
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tubed said:
I don't have a capacitance meter.
I don't want to second guess the reliability of the +/-10% Bennics, or any of the other caps I've purchased. When installed if the bass sounds off I'd be prone to obtain a meter:)
Click to expand...

All of the Bennics I've bought thru there, and Parts Express, etc, in the last 10+ years have always been more than 10% off. Usually around 15% higher(or more) than rated value. But that's about normal for most basic electrolytics.
 
yeah, both the Bennic and PE electrolytics tend to be at least 10% high. never had one measure under spec, that's for sure.

what i would do to replace a 1200uF cap, for example, is order 5x200uF's and 4x50uF's. then you can be pretty sure you'll get close to 1200uF in the end. might not even need the 50uF's!
 
cdfac said:
yeah, both the Bennic and PE electrolytics tend to be at least 10% high. never had one measure under spec, that's for sure.

what i would do to replace a 1200uF cap, for example, is order 5x200uF's and 4x50uF's. then you can be pretty sure you'll get close to 1200uF in the end. might not even need the 50uF's!
Click to expand...

This is interesting and has me thinking I should borrow/buy a meter and check mine the next time I have the woofers out.

Would I need to desolder at both ends or could I check them still attached on one side.
I really like the way they sound now but this talk of 15% out of tolerence
has got me to wondering.
 
i wouldn't sweat it too much now that it's already done. as long as both channels are equally off, 10-ish% doesn't really matter terribly much. i didn't think much of this before i recapped my QLS1's either. but if you do want to measure, you will need to clip the lead on one side of the capacitor.
 
Theoretically and more importantly what will be heard from 1100/1400uf configurations of Bennic capacitors that actually measure 10 to 15% higher?
I still can't quite fathom how these caps function on this woofer design.
The woofer coils "cut-off" frequencies over the desired point but what the caps do isn't clear to me:)
 
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