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Need Help with Koss CM-1030 speakers

I am trying to put a pair of these speakers back together for a friend. A previous owner ( we'll call him "idiot" for short ) hacked out all kinds of wiring and removed factory installed switches, etc... As such, i'm trying to take these back to factory stock and go from there.

The crossover is PHENOMENALLY tough to follow and i've already had Jon Risch try to figure it out. After sending him one of the crossovers to examine, he's pretty confident that he was able to get it right but i would like to make sure. If someone has a pair of these and is willing to tell me where each wire goes ( they are all color coded ), i would be forever indebted.

For those of you that aren't familiar with these speakers, they are large floorstanders that were manufactured in 1979 and retailed for $1100 per pair. The cabinets are beautifully finished, very well built and clock in at 74 lbs apiece. They make use of a 10" vented woofer, two 4.5" cone mids, a dome tweeter and a dome super tweeter. The crossover is of a very complex and advanced design and this is where the problems begin.

Jon's thoughts are that this might have been the first commercial speaker manufactured with a series crossover with impedance compensation, notch filters and padded attenuators built in. He was amazed ( to say the least ) that any manufacturer had the "guts" to use such a highly advanced and parts heavy design in a production model, especially back then. He told me that it may be the most complex passive crossover that he's ever seen and was VERY hard to try and back-track. I fully agree with him and that is why i had asked for his help in trying to figure it out.

In case you are going to suggest that i contact Koss about this, they have absolutely NO records of ever making such a product. I am 100% certain that it is a Koss product though, as all of the labels are still on the speaker and i was able to research them in several different buyer's guides of that era.

I would not bother with such an old speaker, but the drivers and cabinet are all in MAGNIFICENT shape. My guess is that the contacts that work the padded attenuators failed and the "idiot" must have tried to bypass them via hard-wiring. The only problem is that the attenuators have multiple stages and they left most of the wiring just lying inside the cabinet and pulled the switches. As such, there is no way for me to see where anything originally went and that is how we ran into the aforementioned problem.

Is there ANYBODY out there that has a pair of these and can help me out ? Sean
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sean
11 responses Add your response
ozfly
887 posts
 
I don't have them but can give you a couple of leads. First, aargonaut at Audio Review has a pair (you can send him a note by going to http://www.audioreview.com/Amplifiers/Harman,Kardon,Signature,2.1/PRD_115826_1583crx.aspx
and clicking on his name)
Also, there was a June, 1978 review on those speakers in High Fidelity Magazine. You could pick up a copy at http://www.sundial.net/~rogerr/magrevhf2.htm Perhaps that will give you some additional information and enough to revisit Koss. Hope that helps. Good luck.
sean OP
6,231 posts
 
Thanks for the detective work Ozfly. I appreciate it. I'll try dropping Aargonaut an email to see if they can help me out, but i'm hoping that someone out here that has a set of these will "volunteer" to work with me on this. Convincing a total stranger to pull their speakers apart might be a bit of a task if you know what i mean .... Sean
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jasonpgold's avatar
jasonpgold
1 posts
 
Hello, I am the person referred to as Argonaut. I still have a pair of 1030s. Very nice speaker. I bought mine used, and someone screwed with the crossovers in mine too. They had a tendency to break, particularly the switches. I also have three pairs of Koss CM/1020s, one of which I bought new back in 1978 or 79. All have crossovers which are messed up to some degree. Sorry, I can't help any further
daveherm69
42 posts
 
Hi Sean, I hope by now you've had a resolution to your problem.I owned a pair of CM1030's many years ago. They were enjoyable except for an annoying habit of blowing tweeters.I contacted the factory in Canada (Burlington Ontario- if memory serves) and they were great to deal with offering free advice and even sending me a replacement tweeter at no cost.
The point here is perhaps it might be worth a try to contact Koss Canada.They continue to service head-phones that are 25yrs. old. You may be surprised.
Best of Luck.
daveherm69
sean OP
6,231 posts
 
Dave, believe it or not, i still have not resolved the problems with these speakers. After trying to get them straightened out and running into one problem after another, i set them off to the side. After sitting for a long period of time, i ended up sending the crossovers out to Jon Risch to examine. He told me that it might take him a while to examine, but he would get to them.

After looking them over several times, I received several emails from Jon stating that he could not believe how complex this crossover was. He stated that this was the most advanced and complex "series" crossover that he had ever seen in his life. Given that "series" type crossovers have just come into vogue in the last few years ( save for Bud Fried ), this should tell you something about this speaker that came out in 1978.

Jon was finally able to figure things out and sent the crossovers back along with a drawn out schematic. Since that time, it has sat due to another problem that i myself created. I ended up mixing the drivers up. Given that these speakers use multiple drivers that look identical but really aren't, it has once again become part of my "things to sort out when i get the time" projects.

Your post and tip may be just the information that i need to get these things put back together and out of here. I had never thought about contacting Koss of Canada. I had contacted Koss here in the USA and they were NO help. In fact, the technical assistance department didn't even know that they had made "full sized" speakers in the past. They surmised that someone else had purchased the rights to use the Koss name and marketed these speakers with their permission. As such, they were NO help whatsoever. In fact, i ended up faxing them info on the speakers for their records : )

I'll give Koss of CA a try. THANK YOU for taking the time to post this response, even though it might not pan out. It is worth a try and i really do appreciate it. Sean
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dadlet
1 posts
 
I also have a pair of these FINE speakers (cm-1030). They are all original and I listen to them every day. Very little EQ is necessary for a very smooth and lifelike response. Can I help in any way with your problem? (I am not sure what your problem was, so could you fill me in?? Thanks, Al
junk666emailf645
1 posts
 
I realize that this is a very old thread, but for the benefit of anyone who might stumble across it (as I have done) I'm posting anyhow.

I own three pairs of these speakers - now all in factory-new condition. I also own a pair of CM1020's.

I have a factory original service-shop wiring diagram for the 1030's and would be happy to share. The only caveat is that I believe that these speakers went through at least one mid-life revision to their crossover - so the diagram may not match yours.

I would also highly recommend a shop called Speakermart here in Ottawa. They did the full refurbs for me. They also have mapped-out wiring diagrams (proper ones) that they use to repair any of the CM line of speakers. (There was also the CM1010 - which had the novel woofer brass screwed-in "plug" that would change the woofer's characteristics. They have spare plugs!)

I also own crossovers taken from two 1030's that I bought for parts - as well as four mids and two woofers that I believe are in great working condition. I'd sell one woofer and two mids (keeping the others for myself - just in case) to anyone who might need them. Other than stripping another speaker, you won't find replacements to match anywhere - trust me! Since I don't know if the crossovers are good or not, I'd be happy to give one away to anyone - for the shipping cost only. As to the crossover adjustment switches... I have found an exact match from the original manufacturer and a local supplier. I'd be happy to provide that info as well.

These are incredible speakers that can, and deserve to be, used for a lifetime of incredible listening enjoyment.

ps. I have copies of both the Sterio Review and Audio equipment test reports that I can share.

So how to get hold of me since I'd not a member? I always use my full and real name. Google my name. That should refer you to both my work web site - from where you can get my full contact info - and links to posts on other forums where I am a member and from where you can contact me.

All the best.

Jeff Mackwood
adammichal
1 posts
 
Hi,I have CM-1030 and my cross overs need to be repair .
The resistors fell off from the pc board there for I don't
know wher they go .Where can I by new caps and resistors .
Haw were the toggle switches wierd? Need them to.
Thank's for Help.
Adam.
maxdangr
1 posts
 
I have a schematic for the CM1030 speaker and can tell you where each wir of the crossovder goes

Maxdangr
Post removed 
jeffmackwood
1 posts
 

An update to my 2007 post.

I can be reached at the following email address: junk666email@hotmail.com

I no longer have Koss CM spare parts to give away (and I don't think I ever sold any - just gave them to those who needed them) however I have accumulated tons more information on the Koss CM line, including a Koss-original Service Guide that includes wiring diagrams for the CM/530, CM/1010, CM/1020, and CM/1030 - old and new versions as applicable.

I currently own and use six pairs of CM/1030s, one pair of CM/1020s, one pair of CM/1010s, and one pair of CM/530s. That last one is my newest addition and up until a year ago I had never heard a pair. I must say that they are quite impressive.

I am contacted by dozens (and dozens) of Koss CM owners, about-to-be owners, and want-to-be owners, every year, and am more than happy to help whenever I can.

Jeff Mackwood

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