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DCM QED's Crossover Question

A

artbrewer

Active Member
Does anyone here know if the DCM QED speakers used electrolytic caps in the crossovers?

And does anyone know the best way to access the crossover?

Maybe someone has some photos of the crossover or schematics.

Please post them if you have them

Any info is helpful
Thanks
 
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There isn't much known about the QED models, which is probably why there haven't been many responses. You're going to have to be the guinea pig for the rest of us. :D
 
this is the problem speaker and crossover...it is making a weird harmonic ringing type of sound on vocals...heres pics

8" woofer, i think is working properly.
i installed another 8" i had sitting around and it also emits the scratchy ringing sound?

any ideas now?
 

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More QED photos...Dr. Morbius LOOK

Photos of the DCM QED's...
 

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artbrewer said:
this is the problem speaker and crossover...it is making a weird harmonic ringing type of sound on vocals...heres pics

8" woofer, i think is working properly.
i installed another 8" i had sitting around and it also emits the scratchy ringing sound?

any ideas now?
Click to expand...
If it's not the 8" driver, it has to be the crossover. The first thing I would do is replace that 47uF electrolytic cap with a new one. Of course, this means you'll have to do this in both crossovers. It could also be a resistor or a cold solder joint, but I'd start with the capacitor.

You can get the 100V version. It's cheaper and it'll work fine.

http://www.partsconnexion.com/capacitor_ele_mundorf_bipol.html

I would use the blue Ersa 47uF caps with a 3% dissipation factor, but they are out of stock and are being discontinued so they won't be getting any more. The white ones are the next best Erses, but they are slightly out of spec compared to the original caps. If you want to you can use two lower value caps that would equal 47uF in parallel.

http://www.erseaudio.com/Products/NonPolarElectrolytic

I'm with you on the glue. I have no idea why they thought they had to use that goop to secure all of their drivers.
 
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After opening the cabinets i may have found the problem, if this sounds possible?

the cabinet had damage in the area below the woofer which i believe was channeling pressure and sound through the tweeter...
i have filled this bad spot with hot glue and it seems to have cured the weird buzzing or wooshing sound.
 
artbrewer said:
After opening the cabinets i may have found the problem, if this sounds possible?

the cabinet had damage in the area below the woofer which i believe was channeling pressure and sound through the tweeter...
i have filled this bad spot with hot glue and it seems to have cured the weird buzzing or wooshing sound.
Click to expand...
That's great. :thmbsp: However, I'd still replace those 20 year old electrolytic capacitors while you have easy access to one of them. Old electrolytic caps can go out of spec as they age and send low frequency information to the tweeters causing them to blow. Those are Philips tweeters and they probably aren't very easy to find like the Vifas used in later DCM Timeframe and Timewindow models.
 
i will change them out...should be an easy fix.
have recapped many speakers.
My friend is an audio enthusiast and brought over a vifa tweeter for me last night..
it was very hard to hear any difference side to side or old to new...
 
UPDATE: Changed out the 47uf cap in the crossover, and things are sounding VERY good.
This was the main problem with the speakers...low frequency was leaking into the tweeters and causing distortion...
 
artbrewer said:
UPDATE: Changed out the 47uf cap in the crossover, and things are sounding VERY good.
This was the main problem with the speakers...low frequency was leaking into the tweeters and causing distortion...
Click to expand...
:thmbsp: Glad everything has worked out. Another happy ending for a pre-merger set of DCM speakers.
 
I also wrapped them in their new foam socks...these really are a special sounding speaker.
Next...... some logo badges????!!!!!
 
Wrapped them in their new foam socks today...looking and sounding GREAT.
These really are a unique and nice sounding speaker.


Next...logo badges???!!!!!
 

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Hey Now Art,

Where did you get the foam for the QEDs? I have a naked pair, that needs to be dressed up.

--
Finest kind,
Chris
 
I have a set of Mint numbers matching QED's, don't use them anymore. Would Barter town be a good place to list ?
 
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