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Quad ESL Cap mods

Hello,
I have a pair of Quad 988 I'm considering replacing the electrolytic 220uF Capacitor for a film cap...

For those who have done it -- what caps give you the clearest extensions in the highs and improved mids without mudding the low???

Also, who makes a 220uF film cap? All I seem to find is lower values? Is it best to wire a bunch of lower value caps together for a total 220uF (if so, should you mix electrolytic caps with film caps - like some modders do) or is it best to have a single 220uF cap?

I do see Mundorf has 200+uF caps in their Tube Cap line -- are these Mundorf Tube Caps appropriate for the Quad ESL application? how do they sound?

Thank you guys very much for any and all input into this, as I'm just beginning my Quad mod journey...
128x128grateful
face
516 posts
 
I have a 220uf Mundorf here and it's only the size of 1 soda can.
grateful's avatar
grateful OP
104 posts
 
Face,
Thanks for the forum input. Is the Mundorf 220uF cap you have film or electrolytic? What is the reference/catalogue number? Where did you buy? Whats you'r application and how does it sound?

Thank you,
William
grateful's avatar
grateful OP
104 posts
 
Casouza,
Thanks for the great info. Any experimentation with the Mundorf TubeCap? Is the TubeCap appropriate for this type of application?

and When I replace the cap in the Quads -- does it have to be 220uF or can I go less?

Thank you,
William
face
516 posts
 
It is a film cap and is a #71348 available from Parts Connexion.

I used it in a similar application, to filter out bass from a open baffle speaker. I didn't notice any negative effect on SQ, but it was only used on a woofer.

If you use a smaller cap you will lower bass response.

A Mundorf tube cap is not made for this application.
casouza
239 posts
 
William, I have no experience with Mundorf Tube caps, because Tube caps are designed for high voltage tube gear power supplies, not coupling.

Regarding Face's Mundorf cap, it is a great choice if the original cap is rated for 250 Volts or less, however, I maintain my recommendation to bypass any large film caps with a Mundorf 4.7 uF silver / oil. This will provide speed and transparency in the treble range, which large film caps tend to lose due to high internal inductance (side efects of the soda can size).
224.7 uF as compared to 220 uF means that your speakers bass response will extend a couple of Hertz down, not really a factor given the usual 5% tolerance of large film caps and any resistors used within the speakers.
Good luck
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