Should I recap this Fisher XP-1 ??

[OldSubSailor]

A while back I acquired an entire vintage Fisher audio system. Among the items I got is a pair of the original "The Fisher" XP-1 speakers. I want to use them and I'm wondering if the crossovers in them really NEED the caps replaced. The cap, a 4 Mfd 50 V DC (not AC) component appears to be sealed & possibly oil filled. Unlike wet paste electrolytic which, as they dry out shift upwards in capacitance as the dielectric drys and thins, oil filled caps have a very long life and, here's the clincher: my Fluke 179 tells me that the one pictured measures 4.1 Mfd, which is, I'd bet, well within tolerance.

I tried to find the specs for this part but google found only a similar line filter. I'm inclined to just use the speakers as is unless someone can tell me why I shouldn't.

Opinions ??

 

[toxcrusadr]

Sure looks like an oil cap to me too. If it's within tolerance it's most likely OK. I don't have a feel for whether the ESR can drift on these things, but one would think not since they are not drying out and the materials are not exposed to the air to allow any kind of oxidation.

If they sound good, that's another indication to leave them as is. If the highs are muted, that may be the drivers, but could be the cap. I thought I heard that oil caps can have a bit of a high ESR at high frequencies but don't take my word for that. If so and they sound dull you could replace with a poly film.

Very possible it's a PCB cap so if it ever does leak, take precautions and properly dispose of the corpse.

 

[OldSubSailor]

Thanks... yeah, what you say is consistent with what I think I know about oil filled caps. I have them set up and playing right now and I think they sound pretty good considering they're pushing 60 years old. I've just re-foamed and recapped my 4 original large Advents (with poly caps) which are now being used in my newly set up tube audio system, and I have to say that the Fisher's don't seem to be quite as bright. My guess is that it's the old cone drivers versus the 'newer' dome tweeters. That said something I didn't mention is that I've elected to use the Fisher's in my general radio, news & background system in the house, so they don't HAVE to be top performers.

 

[Drugolf]

Tough call for sure. Even though Oil, they are really old. A good film replacement is a safe way to go to be sure they are performing as good as they can and may result in getting a liitle more of the top end back. In general though they will not be able to reach the upper frequency range no matter what you do.

Yours have the cool hard plastic grilles like mine do?

 

[OldSubSailor]

Yes they do have the egg crate grills (to my surprise, my wife really likes those). Removing then without damaging them was a real PITA . I had to grit my teeth a bit prying on that almost 60 year old plastic, but I was able to remove them with just a few nicks inflicted that aren't all that obvious. There may be a trick to it that I don't know. Interestingly when I reinstalled them, then dropped right in and I had to use only a little force to push them under the lip of the case.

Even though they're not as bright as my re-capped Advents, given how I decided to use them (for general listening to the radio etc in the living room) I elected to use them as-is. When I played a really 'hot' cd with a wide dynamic range as a test, I was amazed at how good they sound given their age. So as of this morning, they're reassembled and playing in the living room.