Koss CM-1030's

[RS Steve]

Found these for a song on our local CL. I used the Kirby to pull out a dust cap on one woofer, and one mid, then good old Howards restore a finish to freshen up the veneer. All drivers work perfect, other than two eq switches, and a water mark on the top of one, they are nice.

I also got a Technics SA-R377 receiver with them that looks to be mid to late 80's vintage. It has a built in fan on the back so it must have decent wattage. It's just not anything special in the looks department, the good old black box thingy.

The Koss speakers really surprised me, they sound very good with very good bass for such a small woofer. I plan to do a restore which includes veneer touch up, recap of the crossovers, and replace the switches for the eq.

Any Koss experts please chime in, I have not had any experience with this brand. Looks like a decent score for 50.00. :thmbsp:

 

[nclh77]

Some electrical contact spray may fix the eq switches. Fantastic speakers which will handle a lot more power than that Technics will ever put out.

 

[Erik Tracy]

I had a pair in the 80s when living on campus at college.

I was the 'party guy' when the floor wanted to have a party in the common room.

Great pairing with a Kenwood KA-9100 int amp.

Efficient, room filling goodness.

If all the drivers are working as well as the eq switches, you got quite the 'scroe' for $50! :tresbon:

 

[RS Steve]

Some electrical contact spray may fix the eq switches. Fantastic speakers which will handle a lot more power than that Technics will ever put out.

Oh behave!

I know you want that Technics receiver badly, just admit it. :yes:

I have the Koss's hooked to my Carver M-500T amp, and Phase Linear 2000 preamp, no complaints.

Two of the switches ar broken, which I hear is common. They are very common and not pricey so not a problem.

 

[mtlmn1971]

Holy smokes!! Congrats, That was a great Score!! Looks to be very well built. The speakers look nice too. Haha, Couldn't resist. I have never heard a koss speaker. Those look very impressive. I will be keeping my eyes open now.

 

[RS Steve]

I had a pair in the 80s when living on campus at college.

I was the 'party guy' when the floor wanted to have a party in the common room.

Great pairing with a Kenwood KA-9100 int amp.

Efficient, room filling goodness.

If all the drivers are working as well as the eq switches, you got quite the 'scroe' for $50! :tresbon:

Great, thanks for the information. I have heard the Koss name, mostly head phones though not much else. I believe I have seen pictures of them before but not seen many threads. When I saw these I thought 50.00 was not much to risk since this super collectable receiver was included too. :nono:

I will have to see what size caps are needed, then try and get these crossovers done. I am interested in seeing where they will rank for sound in my current collection, I'm impressed so far.

 

[Balifly]

Great, another Koss saved! :thmbsp:

 

[jtee1340]

PM jeffmackwood he is the man on these

RS- jeffmackwood is very helpful with these. He sent me drawings of the Xovers and articals fron mags etc.
Shoot him a PM.
Great guy too!
Good luck with the recap. I could not get mine out of the cabinets. I had to do the rebuild through the woofer hole! Not fun, but it worked. The crossovers are very interesting. Not your normal looking neat setup. You will see what I mean when you open them up. But it was a very advanced setup for their time.
Look close at the ceramic resistors in the crossovers. The leads have a habit of turning green from corrosion and falling apart. I would replace those along with the caps. Once recapped, they will surprise you even more.:yes:
The switches are a common failure.
Congrats on the find and enjoy the Koss Journey.:thmbsp:
J.T.

 

[RS Steve]

RS- jeffmackwood is very helpful with these. He sent me drawings of the Xovers and articals fron mags etc.
Shoot him a PM.
Great guy too!
Good luck with the recap. I could not get mine out of the cabinets. I had to do the rebuild through the woofer hole! Not fun, but it worked. The crossovers are very interesting. Not your normal looking neat setup. You will see what I mean when you open them up. But it was a very advanced setup for their time.
Look close at the ceramic resistors in the crossovers. The leads have a habit of turning green from corrosion and falling apart. I would replace those along with the caps. Once recapped, they will surprise you even more.:yes:
The switches are a common failure.
Congrats on the find and enjoy the Koss Journey.:thmbsp:
J.T.

Thank you for giving me all the great information. It just blows me away to have these fall my way, it was just me looking for the next project in doing something I enjoy. I figured they were ok, but somewhat kabooki looking when I saw the ad. So getting them up to snuff, and passing them on for a second life for someone else was the idea. Now after seeing how well built they are, along with their very solid, quality sound, I have to really grasp what I lucked into. They really have better sound than many speakers I currently like, which for some reason has my head spinning. I can't imagine why there isn't more interest or chatter about these speakers, it reminds me that there are gems out there that some of us don't recognize. Yep, you could say I'm inspired. :yippy:

 

[jimfet]

Super great deal on some super speakers.

 

[LesE]

I purchased a pair of 1030's back in 1979 and enjoyed them for many years.

In case you don't already have them, I scanned the User Manual and Sales Brochure for the CM Series speakers.


Manual: http://1drv.ms/SErrzP (10 MB)

Brochure: http://1drv.ms/TtliqM (20 MB)

Les.

 

[RS Steve]

I purchased a pair of 1030's back in 1979 and enjoyed them for many years.

In case you don't already have them, I scanned the User Manual and Sales Brochure for the CM Series speakers.


Manual: http://1drv.ms/SErrzP (10 MB)

Brochure: http://1drv.ms/TtliqM (20 MB)

Les.

Thanks Les, I had the sales brochre already but not the manual.

I also have emailed Jeff, the resident expert on Koss. He sent me the crossover schematic so I'm good to go.

 

[RS Steve]

I'm surprised these speakers even produced any sound after looking at the crossovers. A few of the resistor leads were corroded completely off. I did a recap already, but now trying to find the same spec resistors is tuning out to be a challenge. These all say 15 watt, most I find are 10 watt rated.

 

[cablephil212]

PE has Mills @ 12watts, and their general purpose resistors go up to 25watts.

I don't see a problem with using the Mills, but if you want to keep the wattage up there, use the general purpose 20watt variety.

 

[RS Steve]

PE has Mills @ 12watts, and their general purpose resistors go up to 25watts.

I don't see a problem with using the Mills, but if you want to keep the wattage up there, use the general purpose 20watt variety.

I'm not enough of a electronics person to know if the 10 watt rated resistors would be ok.

 

[GoRNR]

Hey Steve-- I recently picked up a pair of Koss CM-1030's from a friend that stored them after a PE took them to his home from another AK'ers location in Wisconsin. Great AK'er friend (mccarty350)-- two thumbs up :thmbsp::thmbsp:.

Anyway, I also contacted Jeff at the time of the purchase and he knows these speakers well. Mccarty350 hooked up audio to them and confirmed some non-working drivers-- probably the crossovers. I have not, however, had time to inspect and confirm the issues.

As far as resistor wattage-- depends on how hard you're planning on driving the speakers I would think. If you are going to use them for parties and extreme service-- then you should at least match the wattage rating of the original resistors. If on the otherhand you intend to listen at more modest power levels, 10 watt power ratings on the resistors mayget you by. One other way to double the power rating would be to parallel two similar resistance rating resistors of twice the ohm rating. So for example parallel two, 20 ohm, 10 watt resistors to get to that 20 watt power rating at 10 ohms. You will want resistors that are fairly closely matched resistance-wise so the power is evenly split between both resistors. This of course adds real estate requirements for mounting and soldering them to the crossover. It would allow you to use the Mills resistors if you can find the correct values to parallel to get you to the original resistor values. Just remember if you attempt to parallel resistors of different resistance values, you no longer evenly split the power across the individual resistors. So you have to be careful paralleling resistors to increase the power rating. It may be worth using a "lesser" quality resistor of higher power rating to avoid overheating the components. Sometimes buying a few low cost resistors will allow you to measure and select ones that are closer to original design values and within tolerance.

These are just some suggestions. I've not gone on a component search yet since I don't know how extensive my crossover work will end up being yet. I'd love to hear more of your impressions on how yours sound. Keep us updated. :yes:

 

[RS Steve]

Hey Steve-- I recently picked up a pair of Koss CM-1030's from a friend that stored them after a PE took them to his home from another AK'ers location in Wisconsin. Great AK'er friend (mccarty350)-- two thumbs up :thmbsp::thmbsp:.

Anyway, I also contacted Jeff at the time of the purchase and he knows these speakers well. Mccarty350 hooked up audio to them and confirmed some non-working drivers-- probably the crossovers. I have not, however, had time to inspect and confirm the issues.

As far as resistor wattage-- depends on how hard you're planning on driving the speakers I would think. If you are going to use them for parties and extreme service-- then you should at least match the wattage rating of the original resistors. If on the otherhand you intend to listen at more modest power levels, 10 watt power ratings on the resistors mayget you by. One other way to double the power rating would be to parallel two similar resistance rating resistors of twice the ohm rating. So for example parallel two, 20 ohm, 10 watt resistors to get to that 20 watt power rating at 10 ohms. You will want resistors that are fairly closely matched resistance-wise so the power is evenly split between both resistors. This of course adds real estate requirements for mounting and soldering them to the crossover. It would allow you to use the Mills resistors if you can find the correct values to parallel to get you to the original resistor values. Just remember if you attempt to parallel resistors of different resistance values, you no longer evenly split the power across the individual resistors. So you have to be careful paralleling resistors to increase the power rating. It may be worth using a "lesser" quality resistor of higher power rating to avoid overheating the components. Sometimes buying a few low cost resistors will allow you to measure and select ones that are closer to original design values and within tolerance.

These are just some suggestions. I've not gone on a component search yet since I don't know how extensive my crossover work will end up being yet. I'd love to hear more of your impressions on how yours sound. Keep us updated. :yes:

Thanks for the advice, I will look a little harder for something rated for 15 watts, if I have to I will use the 10 watt ones. I don't ever go over 12 oclock on the volume.

 

[RS Steve]

Just thought I would post an update, ordered Mills resistors for the crossovers, and installed new eq switches. The switches are a little longer, and black in color compared to the originals that are white, shouldn't be a problem though.

 

[RS Steve]

I finished up the CM-1030's yesterday, and have had them playing for a few hours. These are some very good sounding speakers, they have a very solid smooth sound to them. I would say the best way to explain the sound would be to say they have the deep solid bass of an AR3a, and the the very detailed highs of an ADS L-880. They are a huge surprise, probably easily in my top 10 sounding speakers I have had the pleasure to enjoy. Add the beautiful pecan finish, and quality cabinets to the mix and you have some real sleepers. I have them next to a pair of Klipsch Forte's doing a compare, the Koss CM-1030's are smoother, and better balanced sounding. I'd say, if you ever find a pair, grab them. :thmbsp:

 

[OldSch00l]

I have a pair of CM-530s in my computer/secondary system, I have always been fond of their sound. I am sure they aren't flat like my ARs but there is just a warmth, and as you say, authoritative and competent low end that I find very appealing.