Advice on, and Source, for capacitors

Hi

I'm using Quad ESL63s with Gradient SW63s. Until recently I was using a stepped-ladder-attenuator as a volume control and had adopted a very good tweak from Mats Törnqvist's site (http://user.tninet.se/~vhw129w/mt_audio_design/index.htm). This routes the signal to the amp driving the Quads via a capacitor rather than via the Gradient cross-over. Suitably chosen the capacitor rolls-off the Quads below ~ 100hz and alters the phase such that at ~ 100hz it is in-phase with the Gradients (once the signal leads to these have been reversed). [By the way if there is anyone out there using ESL63s with SW63s, this is a "must try" tweak, very cheap, totally reversible and with a fantastic benefit!]

Recently I have replaced the stepped attenuator with a Promitheus Ref 4 TVC (thanks Larkrise!). Initially I connected the TVC directly to my main amp and accepted that I would have a rather uneven respsonse as the SWs kicked in. I was really impressed by the detail and sense of depth in the sound, but obviously I needed to sort out the lower end.

Currently I have my old capacitors (Musicaps- I think) sitting bewteen in and out terminals in a separate enclosure. Obviously this requires another set of interconnects and is less than ideal. The frequency response is now more even, but I think some of that stunning detail has been lost.

Hence, I want to try a solution which eliminates the need for the extra interconnects - and that, finally, brings me to my requests for advice (apologies for the long-ramble).

A) Any views on what would be suitable makes of capacitors for this duty (I need 33nF, but only need 2)
B) Any ideas on suitable suppliers (I'm UK based)
C) I read somewhere (one of Zanash's posts?), that it is always advisable to by-pass capacitors with smaller ones of about 10% of the value. Would that practice be applicable in this application?
D) Is there any reason why the tweak described above would not work with a TVC?

Any advice on this would be much appreciated.

 

If all you need is 33nF, which is a pretty tiny cap, then the choice has to be film types - preferably polystyrene (usualluy only available in 10nF and below) or polypropylene. Have a look at Rapid Electronics here here for Wima FKP2s; you could make up the value you need by paralleling 3 x 10nF + 330pF. These are film+foil types, and simply outstanding capacitors albeit small values. An equivalent choice would be these Wima MKS2, 1 x 33nF. I really like the MKS2 for coupling and decoupling applications - they really are about as good as it gets, and comonly avaiable up to 3.3uF.

Bypassing is of no use for film caps. It's usually recommended as a patch for the worst properties of large electrolytic caps, and even then it's definitely a Faustian bargain. Usually it is better to use one, good-quality cap IME.

 

I'd agree with that ....or try paper in oil I've some 0.22uf if you want to try them ...pm me