Thoughts on replacing caps in 30 year old speakers

Stolen makes four basic grades of cap, in ascending order: metallized polypropylene (black), tin foil and polypropylene film (white), metallized teflon (blue), and tin foil and teflon film (green). They sound very different.

Metallized poly is the least expensive of the audiophile grades. It sounds relatively smeared. Tin film and foil is a big improvement in clarity, but this may not suit your system as a whole. I find that teflon adds a slight edge, which may make your system unlistenably sharp, or much more life-like, or something in between. As ever, YMMD.

In critical applications I divide the critical value into 3: 1/3 Solen teflon f&f, 2/3 styrene. This gives me a slight edge from the teflon, and a slight rounding from the styrene, for a pleasingly neutral sound. Unfortunately Solen does not sell styrene.

Not only would I do it, I have done it. As you can infer.

To clarify: I have upgraded KEF's, Magnepans and Quad ESL's, not Thiels. But if you like their sound, why not? 

When I upgrade to film and foil, I expect increased clarity and decreased harshness. I have found that polypropylene is rounded, polystyrene is very slightly rounded, teflon is slightly edgy. I would never replace old metallized with new metallized. I get good results with MIT Multicap f&f. YMMD

Speaking about Thiel CS7 I have one set since 1997. I changed twice the fragile tweeters in these last long years. Last month again one of my tweeters started to give some "ssshhhhh" on piano and voice recordings. I contacted Thiel Audio for replacing it but they don't have any spare parts because Scan Speak closed production of this driver.
Someone of you can help me in some way to try to recover my old but wonderful sounding CS7s? Thanks!

Hey @fd60 Take your questions to DIYAudio in the multi-way forum. Take a picture of the driver, if it's marked as a SS driver the part number will be on it, otherwise maybe contact Thiel and ask what they were using.

you'll find lots of speaker builders and repair experts in that forum.

Best,


Erik

My point to asking Thiel is to see if you can find either a used or NOS replacement diaphram or driver. If it's a standard SS part then it would looking for it by the standard part number will give you more options to search for, but if it truly was a Thiel-only part then you're going to have to find a used or NOS replacement for the Thiel.