SpeakerTalk

Tincho Biedma

hi everybody,

i just have purchase two C40, i allready have another pair from my dad. The matter is that i've discover a very noticiable diference (aparent lack) in the response of detail in the HF, of one par over the other. Also in one of the new pair, both woofers moves in a substantial "long path, loose like trajectory". Are all these issues a problem of unbalance or burnt-out in the Dividing Networks.

I'd appreciate your comments and guide

Martin

ColinR · Posted: Fri Mar 23, 2012 4:15 pm Post subject:

The C40 crossover consists of 5 capacitors and 2 inductors, probably a bass half section plus a treble tee section with the other capacitors hanging about to help roll off the second bass unit and a notch filter of some sort, so it's simple and not power hungry.

Larger than normal bass excursions and a loss in treble performance can usually be explained by “party time” where the voice coils have been slightly cooked (increased DC resistances) due to having been overdriven.

Crossovers are generally damaged following sustained misuse after it has occurred in the drive units.

If the best six drive units are in your dad's old speakers, take the others back and get a refund/compensation.
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Tincho Biedma · Posted: Fri Mar 23, 2012 4:49 pm Post subject:

Tincho Biedma · Posted: Tue Apr 03, 2012 3:31 pm Post subject: C40 (restoring cuarteto)

People,

After made a complete test with pink noise, sweeps and concentrated listening, i've found that both T33 SP(1211) tweeters in my former C40 pair are bad; no detail and quite dull. The others two T33 SP(1211) tweeters in the new pair acquired sounds realy nice. I face a situaction were the "good" woofers are in one pair of speakers, but the "good" tweeters are in the other ones. So, i've swaped de T33 SP(1211)'s to have one pair performing like God say they should be!.

Now what? i have a remining pair of C40 with one speaker having both woofers B200 SP(1205) performing nice, but bad Tweeter on in.
The other speaker of this par with all units bad: two woofers B200 SP(1205) with larger than normal excursions, an apreciated scrape like sound when 20Hz fixed tone applies in one unit; plus the T33 SP(1211) tweeter on it with dull performance.
A NOTE APART: i remember peeling off the "golden paint" that coats the surface of the dome, a cup of years ago. It was almost all flaked. Recently i've read over there that certain types of Tweeters utilizes ferrofluid, and could be prone to dry. Is this a possible cause of it's bad performance???
May i "refill" these tweeters with that ferrofluid? and try to recover it? Its a DIY procedure or only for pros?

I've allready purchase a pair of these tweeters in good working conditions (states) to a persona on eBay. It's caming to south!!! But i wonder if i can achive the restoration task and not ends up in the trash.

I'm expecting your comments and guide fellas.
Thanks
Martin

ColinR · Posted: Wed Apr 04, 2012 10:42 am Post subject:

Tincho Biedma · Posted: Wed Apr 04, 2012 1:09 pm Post subject: reciling

ColinR, interesting information.
About woofers rebuild, i'm in contact with a guy here in Buenos Aires and with Van L. Speakerworks at Chicago, USA: http://www.vanlspeakerworks.com/repairs.htm

i woonder if exists some KEF house-person specialized in this kind of woofer recoil job in USA. Do you know anyone else?

Best regards
Martin

chris · Junior Contributor 10+ Joined: 04 Aug 2013 Posts: 11