Vintage KOSS CM/1020 speakers

[Rob.]

Hi, I picked up a free set of vintage Koss CM 1020 speakers today.
Supposedly, these are extremely nice/desireable speakers.
The cabinets were made by a grandfather clock manufacturing company in Zeeland MI, H.L. Hubbell Mfg. Co.

They work, but I believe the crossovers need to be rebuilt as 1 tweeter
doesnt work as well as the mid and tweeter switches as well.

Anyone know who can rebuild these crossovers for cheap ?
What would this cost ?

thanks

PS: Heres a vid I found on youtube of them.

http://www.youtube.com/watch?v=7xke8Uo8o4s&feature=relmfu

sample pic

 

[krimney]

clean the switches

could be you have one bad tweeter, and after all these yrs the switches may be badly corroded. clean up the switches and drop in a new tweeter(looks like a philips) and you may be good to go.

 

[Rob.]

could be you have one bad tweeter, and after all these yrs the switches may be badly corroded. clean up the switches and drop in a new tweeter(looks like a philips) and you may be good to go.

hmm.. Ok.. deoxit ?

 

[budgetaudio6]

A very good speaker. My pair of JBL l166 and koss are very close sonically. With teh nod towards the Koss. Same with tannoy 12 monitor gold. With the tannoy and the koss. Its pretty much flip the coin to determine which sounds better.

One note though is the Koss have better bass...But tannoy has a warmer sound A trade off from one to the other. Both very good.

 

[JDub]

Anyone know who can rebuild these crossovers for cheap ?
What would this cost ?

The obvious answer to this is that you can, if you have a couple of screwdrivers and a soldering iron. I replaced the caps in mine with a mix of electrolytics and film, and replaced the switches at a total cost of around $50.

 

[Levitious]

I have a pair of CM/1030s, the flagship speaker of the CM line and bigger brother to the 1020s, They are beautiful speakers and the sound is to die for imho, Never heard the smaller once (1020,1010,and I think 540 was also one, might be off with the 40 part)

I'd suggest you contact Jeff Mackwood if you need any information on these speakers, If he doesn't come in and comment on this thread himself (which would surprise me if he didn't) i

 

[JeffMackwood]

Rob contacted me and I will be in touch with him to see what I can do.

In general (re the CM line of speakers)...

All of the original swicthes will have failed (physically - not usually electrically) by now. Basically they snap off at the root and stay switched to whichever position they were last in.

Tweeters fail but not all that often really. It's mostly a matter of failed crossover components causing open circuits.

By now just about every original resistor will need to be replaced. You can find matching values but not the same (extremely tight) tolerances. Do the best you can and they should sound "original."

Caps drift out of tolerance. However the last pair that I acquired (I have six pairs now) did not need to have any replaced.

All my crossovers get refurbished at SpeakerMart in Ottawa. Bill (the owner) tells me you can send him the board and he'll do it. I've dropped off pairs of speakers and he cleans things up etc. to "like new" by the time I get them back.

There's a thread over at "The Audio Annex" about a set-up / listening test that I did this past summer. Had all three speakers in the CM line (1030, 1020, 1010 - the 530 pre-dates them and is fairly different and generally not considered part of the "classic" CM line) set up in my living room. First ever such set-up that I know of - outside of possibly some showrooms way back when. Two pretty extensive reviews of them posted on that thread by friends who visited.

I've seeded quite a few sites with this address junk666email@hotmail.com for anyone who wants to know more, get copies of wiring diagrams, trade reviews, etc.

Jeff