Anybody else have/had a CM Laboratories Amp?

[louped.garou]

Is a CM Labs 'Model 35 MRM' basically the same amplifier being discussed here?

and i believe the involved parties were: Wayne Chou & Morris Richard
CM labs did OEM stuff for Bozak (and others) back when....

 

[Brian]

Those are not the same as the 35. Did you win them? I noticed them and the matching preamp and it took all my strength not to pull the plug on them. The complete set went for absolute peanuts. The mono amps were a professional amp and I believe formed the basis for the mono Bozak amp. They look like easy projects but, I wonder what happened to the 1 missing handle.

 

[louped.garou]

Those are not the same as the 35. Did you win them? I noticed them and the matching preamp and it took all my strength not to pull the plug on them. The complete set went for absolute peanuts. The mono amps were a professional amp and I believe formed the basis for the mono Bozak amp. They look like easy projects but, I wonder what happened to the 1 missing handle.

ah...

thanks for the info, I'll try to ping Mr. Chou on DIY for more info on these particular amps....

I did win them...

yeah, i agree peanuts... although shipping is a little steep...

i have some spare handles here, but I normally take them off before mounting in my racks anyhow.... I tend to bum them occasionally if i leave them mounted....

 

[Brian]

You may also try him on the Yahoo Bozak sight as he hung around there as CM Labs made Bozak equipment for a number of years and he has helped a few there in bringing back the CM units.

 

[louped.garou]

Thanks!

 

[Meridian23]

CM LABS 912 and CM300...

I know this subject was some years ago. But i came across a CM LABS 912
power amp and a CM300 pream. I buy the power amp 912 but not yet sure
if i will also get the pream. the power get the direction of a technicien for
a total rebuild. SO i start to search the web for more info and i found this
tread. Both unit was $350 not a bad deal considering their relative rarety.

I will let you know my impression when the power amp return from rebuild.
The amp was not broke but just to get the best from this CM LABS 912.

The seller was lucky enough to get 2 kit so he sold me one and will also
perform a total rebuild of his 912...

 

[TOOBDUDE]

CM Labs 912a

Dear Meridian,

I too have a CM Labs 912a amp. In fact, over the years I have been able to obtain the entire system from the Audio International owned period of CM Labs - the CM300 preamp, the LAD200 turntable and the CM15 Servostatic speakers. Unfortunately, they are all in need of restoration so I have actually never heard them together.

At that time, it appears Wayne Chow was no longer with CM Labs. Richard Majestic was the head design engineer and Peter Ledermann also worked there. If it is not too late for you, perhaps you would do well to send the CM912a to Soundsmith to have it restored. Peter Ledermann owns the company and Richard Majestic is also listed as Senior Associate Engineer. What better place to have it restored than by the people who made it.

It appears there are no pictures on the internet of the CM912a amp so I'll get out my camera and put some up here this weekend. The 912 appears different than the 914 so I do not think the 912 is just the 914 with meters.

I want to restore my CM Labs pieces but I have several other projects to complete first. What I was going to do when I got around to it, is contact Peter and Richard and ask them for advice on any upgrades. In addition to the standard capacitor replacement, I was wondering if upgrading the resistors to Caddocks or Vishays would be of benefit. Maybe we can get either Peter or Richard to give us some insight into the Audio International period of CM Labs. There really isn't much info out there.

I don't think there were many CM912a amps made. You never see them for sale.

 

[Nat]

I'd love to see pictures of all three items you have -- I've never heard of a CM turntable or speaker, so my interest is piqued.

 

[TOOBDUDE]

CM Labs

Alright, here are all the friends together for the group shot .
CM LABS LAD200 Turntable, CM300 preamp, CM912a amp, CM15 Servosound speaker.

 

[TOOBDUDE]

CM912a

Here are some more of the 912a.

The amp has 2 "modules" for the right and left circuit boards

A closeup of the back plate for one of the modules. Can you guess what the Cinch-Jones connector is for?

 

[Nat]

Very interesting -- unlike any CM or Bozak CM stuff I've seen before. I'd love to see more of the turntable -- it looks like it was, at least in part, sourced from CEC, but its hard to discern any details from the picture because of the angle.

 

[TOOBDUDE]

Lad 200

The turntable was built for CM Labs by London Acoustical Developments. Originally, it came with a Sumiko MMT tonearm. (The MMT is a Jelko SA370 tonearm). It is an all metal plinth with the platter and tonearm separately isolated on bushings. It is manual.

 

[releone71]

A closeup of the back plate for one of the modules. Can you guess what the Cinch-Jones connector is for?

Seems like there is sorta on board phono stage for each power module... :scratch2:

 

[Brian]

From the label it appears to be designed for a feedback loop from some speakers for control. There were a few companies in the '70s and earlier that experimenting with feedback control between the speaker and amp. I can not remember the company but seem to remember one out of Texas that came out with it and Philips incorporated it in their amplified MFB speaker line. This is a WAG but, as CM had at least one speaker for it may have been something it was working on. The label seems to preclude a phonograph preamp and it would not be logical in a power amp anyway.

And interesting amp and extremely logical for a number of applications in addition to home audio such as where down time is not acceptable and having wholesale backups or ability to do a complete pull and replace not practicable. Looks like it would be faster and easier than with the Marantz 15 and 16s that were dual mono amps. Only limitation with the CM would be apparently if the power supply is on the chassis and not on the modules which it appears not to be.

It is sad there is not a database or website dedicated to the make as it might be very interesting. The company lasted much longer than many like Mattes but, it seems little is known about it and the products as well as its relationship with Bozak.

 

[Nat]

I believe the company in Texas that had motional feedback speakers was Erath. I think they may also have been known, even if only by mistake, as Earth. My memory is that the owner was Lou Erath, and his speakers had a good reputation, but required owners to actually go into their amps and attach wires to one point in the circuitry, which obviously limited their mass acceptance.

It's worth noting, as the OP did that the equipment shown is from a later iteration of CM -- most of the info out there on CM focuses on the time pre Bozak and then the period where they were associated with Bozak. The items shown here appear to be from the post original Bozak era, though I'm just guessing. I don't get how CM/Bozak connection worked in later years, though I do remember reading that Peter Lederman worked at Bozak at one time.

 

[sixthday]

Interesting unit. How much power for the 912a? 200wpc?

Here are some more of the 912a.

The amp has 2 "modules" for the right and left circuit boards

A closeup of the back plate for one of the modules. Can you guess what the Cinch-Jones connector is for?

 

[Nat]

Given that the Cinch Jones connector is labelled feedback speaker, there's not much mystery as to it's purpose, I think.

 

[FONSguy]

I had the CM620 DJ Mixer. Poor quality parts but after a tech went over it and swapped out the crappy sliders and cue-main switches it worked for 7 years in rough busy service. Didn't sound bad, and did sound full range. Wish I still had it. The circuit board cracked and the tech said it wasn't easily repairable.

 

[Meridian23]

cm 912a restoration

Thank you for the pic...

My 912a is silver faceplate. I wait the unit return from a tech
shop who he will be rebuild. I will comment later.

How sound the 912a????

I just place a kit for sales 912a + Cm300 here on AK because member seem to
know about electronic. The 914a who was $400 and 912a $800 receive a
wonderfull review on audiogon. Someone can comment the sound quality of the
912a. My unit quick the seller directly to the shop tech and i have not got the
chance to ear...

 

[TOOBDUDE]

The 912a is made to work with the Servosound speaker. The CM15 has a corresponding Cinch-Jones connector. It uses 2 of the pins for the power to the speaker and 2 for the feedback circuit. The CM15 was from a Lewis W Erath design. There is a Yahoo group will lots of info on the Erath speakers and the schematics for the feedback circuit and how to incorporate it into amps/receivers of the time period.

http://www.audiokarma.org/forums/attachment.php?attachmentid=524526&stc=1&d=1404693072[\IMG]

[IMG]http://www.audiokarma.org/forums/attachment.php?attachmentid=526638&stc=1&d=1405531177[\IMG]

[IMG]http://www.audiokarma.org/forums/attachment.php?attachmentid=526639&stc=1&d=1405531209[\IMG]