Review: CM Labs CM 300 Preamplifier

Category: Preamps

Although CM Labs was much better know for thier over the top power amplifiers, than their preamps. None the less the CM Labs CM 300 preamplifier was their crowning achievement in preamplifiers. It as well was the cosmetic match for the CM Labs 914 Power Amplifier.

Produced from 1977 to about 1980, CM Labs was competing with the likes of Threshold,Levinson and Krell. And while their Power Amps competed very well in that area, the Preamps did not enjoy the same status. Perhaps one of the reasons is that Threshold,Krell and Levinson had produced low profile preamps that were about half the size of the CM Labs CM 300 preamp. Although weighing about only 15 pounds the CM 300 measured approx., 19" across the front(EIA Standard)about 6" in height and about 15" in depth. By far larger than the Threshold,Levinson and Krell of the day.

The CM 300 was a full featured preamp, with bass and treble controls, high and low filters,loudness compensation,two tape monitor,tone control defeat. Inputs were tape1,tape2,aux,tuner,phono1 and phonor. Mode Selector,left,right, L+R,Reverse,Stereo. Completed by Balance and Volume control as well as headphone jack and power on/off switch. This layout was more in keeping with the design parameters of McIntosh and Marantz of the day,than with the Threshold,Levinson and Krell. Build quality was very good and on par with the McIntosh preamps.Mil-Spec switches and controls and circuit board. RCA connections on the back were on an apron with a cover.Similiar to the Bryston BP-1, and Van Alstine Model 1 arrangement. Also on the apron is the phono cartridge gain loading adjustment. Very nice feature as one can dial in the precise amount of gain as dictated by the phono cartridge manufacturer and it worked very well indeed. Standard nickel plated RCA inputs as opposed to the growing trend of tiffany plated at the time,which continues to this day.

Not the minimalist approach to preamp design that was beginning to take hold at the time, it did offer the end user with a wide variety of features, that soon would be passe' by other manufactures trying to get the purest sonic signature. But with all the cavets, the CM 300 was and remains one very fine preamp, no one has to make an excuse for.

Sonic signature was at times breath taking, with great depth and wide sound stage, with definition and clarity that few possesed at the time. With that being said the Threshold,Levinson and Krell exceeded the performance level of the CM 300, but not by a far margin and was considerably less in overall costs to those exaulted brands. If CM Labs had packaged the CM 300 in the style of the Apt Holman preamp, it would have gained far more acceptance than it did, as the trend in preamps was headed to the slim line concept.

For all the prowess that CM Labs had with power amplifiers,they never came to grips with their preamps. Although the CM 300 received critical praise at the time,most due to its phono section, it was the size of this preamp that was its achilles heel. Most just could not accomodate its size in a rack or stand. However if one could not afford one of the exalted brands, the CM 300 offered a solid alternative with little loss in overall signature and worked quite nicely with a wide variety of power amps,that were available at the time.

Not long after the release of the CM 300, Bryston released the BP-1 preamp and that pretty much took away any success the CM 300 had going for it.And later on the Apt Holman preamp spelled the end for the CM 300. But while it was around this was one very special preamp and reamins worth seeking out today. These are becoming very rare and hard to find today, and most will need service of some kind of service or preventive maintenance. With todays better parts and wiring a refurbished CM 300 would be a preamp of extraordinary performance levels.

Pictures show the CM 300 preamp along with the matching CM Labs 914 power amplifier. These were ordered with the optional wood sides,rack handles and on the power amp the LED clipping indicators. You see in those days if you wanted a CM Labs product, one just did not go in and buy off the shelf. They had to be ordered and you selected the finish,and options you wanted at the time,paid up front and waited some two to four weeks to get it. CM Labs were never very good at marketing. Most likely sales were lost to those dealers that could produce on demand products after the demostration. Product in the loop for immediate delivery did not happen with CM Labs. In essence all the products from CM Labs were built special order for original customer.

The CM 300 cosmetically was a stunning visual preamp. With its solid wood sides and rack handles,bronze face plate and silver controls, gave notice that this was a serious preamp for the discerning audiophile. Controls had a positive feel to them and gave the user a feeling of rock solid quality above its price point.

I no longer can find the spec sheet for the CM 300, but suffice to say CM Lab units always performed well above the published specifications.

If one has a need for a full featured preamp, this in my opinion where the search should begin. Although not many audiophiles gave them up and the search will be long indeed. But should one come around grab it fast.

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Hi Ferrari,

Saw your thread and wanted to ask about the CM labs 914 amp. There is one for sale elsewhere and was looking for owners with the piece. How are the sonics(bass,top end, mids, etc). I listen to jazz primarily. The amp in question shows with no rack handles and I believe is black in color. Hope you can advise and thanks for the pics. BTW I believe this amp has the letter a after the 914. Enjoy the music!
The 914A was a further refinement of the original 914. Although I cannot hear a difference between them and have had both. If jazz and classical is your bag, then the CM Labs 914A is great amp. Can drive damn near load. For a time used mine to drive Acoustats, if it can drive those monsters I feel sure it can drive anything out there.

However do to their age now it would be wise to have it serviced and have the caps upgraded along with some other parts improvements.

But if you can find one and have it serviced it is a killer amp that is overlooked by most.