Re: Restoring & modifying vintage speakers

Henri — Mon, 02 Mar 2009 16:36:54 GMT

Refoaming is an option, I have some experience working on speakers but eight small 3" drivers that require more precision than large woofers = sniffing glue for at least three hours, maybe more, which is not exactly tempting. I've just spent an hour or so re-doing one of the frets and ventilation isn't the best possible when the temperature outside is in mid 20's F. That's been bearable only because the new cloth is, dare-to-be-different, pure white and I'm anxious to see what they'll look like when they're finished.

Then again, if there's a real chance of improving the midrange with different/better drivers, I'd rather do that.

Re: Restoring & modifying vintage speakers

BartJY — Mon, 02 Mar 2009 16:20:27 GMT

Henri:
Finally, my Pentas are officially victims of foam rot now.

Have you considered refoaming the speakers? It's pretty easy to do and there are dozens of refoaming companies around if you'd rather not do it yourself.

http://www.simplyspeakers.com/15refoaming.htm

Good luck

Bart

Restoring & modifying vintage speakers

Henri — Sun, 01 Mar 2009 09:04:06 GMT

Earlier I wrote a short comment about the differences of the characteristics between CX 100 and C 75. Yesterday I replaced the drivers on a pair of CX 100:s and here's a slightly more detailed review:

As before, the imaging/soundstage isn't still quite as good as C 75's, but both midrange and bass were improved immensely. It now feels that CX 100 produces more fairly clean (upper) bass and issues with dirty midrange, which caused a sligtly nasal tone, were completely gone. The old drivers weren't in that bad shape, they had been re-foamed at some point, but something had happened with them. I'm very glad I replaced them completely, they sound like brand new speakers now, which - essentially - they are. My other CX-series speakers are definitely in for new drivers shortly. This has raised a question if it would be feasible to replace the drivers on C 75:s, they're supposedly original (well kept, no signs of foam rot) but if new drivers can make such a huge difference, these could be real winners.

As a sidenote, I found a way to clean white frets - with a nailbrush, warm water and diswashing detergent. Sounds brutal, but the ones on all-white CX:s were so incredibly dirty that I had nothing to lose.

On to the next issue I currently have. Beovox 5000 panel speakers have very clear and even analytical tweeters, but midrange is horribly blurry. This is particularly evident with movies, to the point it's difficult to follow a dialogue. I've tried changing the placement and angle, but nothing seems to help and if I experiment more, my wall is going to look like swiss cheese. I'm planning to recap them next week, but I'm not convinced that it'll suffice. Has anyone else had similar problems or is there a known solution I just haven't come across yet? Even the bass is quite allright and I have a Sunfire True Subwoofer to cover the subsonic range the 5000's can't - these speakers show a lot of promise and considering how great they look and how well they blend in with the interior, a problem like this is very frustrating.

Finally, my Pentas are officially victims of foam rot now. Two of the midranges are rapidly losing their suspension foam and I'm torn between two possible options: replacing all 8 with original drivers or finding better quality 3" 4ohm replacements, possibly wideband drivers. The latter is a fascinating option, but because the specs of original midranges can't be found (anywhere?), the only way to do it is by trial and error, measuring free-field frequency response. I do have access to anechoic acoustic lab but transporting speakers back and forth will be a lot of trouble. Pentas aren't that bad in stock form, but there's some room for improvement. Has anyone experimented with replacing midranges with different units and, knowing that there aren't that many 4ohm drivers on the market, can someone point me to the right direction where to start?

Phew. My house is slowly transforming into a 80's speaker museum and, being quite critical with sound quality as well, this may be a bit more than I originally bargained for. Then again, it's a lot of fun, too - I remember drooling over quite a few of these when I was a teenager and finally owning several pairs of various B&O vintage speakers is soooo satisfying.

Not to mention that I spent another hour listening to Beolab 5:s this week. They're simply damn fantastic speakers, sounding even better when you've listened them for a while. Addictions can become quite expensive quickly, my wife has already mentioned that "we" want them in white, complete with matching BL3 surround speakers and a BL7-2 center... [:'(]

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Re: Restoring & modifying vintage speakers

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Restoring & modifying vintage speakers