Bozak DL

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 Prior to the development of the widely accepted Bozak DL disco mixer Bozak had toyed with several factory designs long before the DL version ever appeared. The first 2 dedicated DJ mixers offered were a  long style chassis CMA 10-2D with no VU meters and a modified mono input stereo output CMA  6-2S that had similar internal workings with VU meters.  

The main board used in the special factory modified CMA 6-2S unit was a physically cut down 10-2 board with 8 mono channels. The input channels went from mono to stereo by using mono channels 1 & 2 with mono phono preamp cards installed becoming stereo phono channel 1. Stereo phono channel 2 developed stereo signal from mono channels 3 & 4 with mono phono preamp cards also installed. Auxiliary channel 1 stereo signal came from mono channels 5 & 6 with jumpers installed making a 3rd phono channel possible if required. Auxiliary channel 2 was a direct hard wired potentiometer that bypassed the main board. Microphone 1 and 2 used the remaining 2 main board mono inputs to become stereo microphones by using a switch to send the mono signal to both left and right channel internal output amplifiers. A small number of these custom factory units were modified and put into service while designers worked on the new to be released CMA 10-2D that was a physical cut down version of the modified CMA 6-2S without meters and developed exclusively for disco-tech DJ use.

Enter the CMA 10-2D. The idea behind the CMA 10-2D was to bring a production unit with the features disco-techs required in a more compact package. It would be a smaller rack mount chassis, have the features being requested, and be easily field serviced. The mixer was not developed as fast as anticipated and required more man hours to assemble than originally planned. The mixer still incorporated mono channels that became stereo as the original modified CMA 6-2S. It was produced in limited quantities even though orders for the club mixers became demanding. In house development of the 919 stereo control center would be where designers would turn to develop a true stereo serviceable disco-tech mixer.

 The 919 stereo control center developed in house and with the German company CMA (Commercial Manufactured Audio) was right in front of everyone's eyes and was the logical unit to work with. It was modular, easy serviced, had the features clubs required, and was a true stereo mixer. All needed to package it was a new chassis and mainboard. Like anything else there were issues in the beginning for the early CMA 10-2DL mixers,  but most of those issues were physical corrections and including the confusion of the designated model D becoming D1 then corrected to DL on early units. The electronics were directly brought over from the 919 to the D1/DL with little modification and the mixer could be assembled in half the time as the short chassis D mixer with the 10-2 style interior components. The DL was easily serviced, offered all disco-tech requirements, could be upgraded in the field, and most importantly all the extensive electronic development was all ready done. The stereo DL format was and remained through out as 2 Phonos, 2 Auxiliaries, and 2 Microphones. Variations to the DL would evolve but the internals retained all the 919 electronics till the end of production. If you look at the part numbers on DL mixer internal cards you will see most include the 919 designation in their part number

    The CMA 10-2DL production ran 14 years out of Connecticut and 5 years out of the Florida location.  During this time variations to the DL were developed as demand dictated.  The first and most noticeable change to the DL was the 2 Phono channel upgraded to 3 Phono channels, 2 Auxiliary channels and 1 Microphone channel. The Cue switch became 5 position instead of the standard 4 position making all sources excluding the microphone available at the front monitor jack. This upgrade was so popular at the  service department and in the field that it was obvious to the sales department a 3 Phono factory version was inevitable.

The CMA 10-2DLS was the first visible factory change to the original DL layout.  The first run had misprinted CUE positions on the faceplate but was corrected with its advertised release along with the CMA 10-2DLA. These 2 new mixers along with the original DL gave operators and installers the choice between the original layout, a mixer with 3 Phonos, or in the case of the CMA 10-2DLA optional 4 Auxiliary inputs as the cd format was becoming popular. The next mixer to be added to the evolution was the CMA 10-2DLB. This is the same as the CMA 10-2DLA with 1 Microphone channel removed and a 3rd switchable Auxiliary in its place making 6 Line inputs available. All factory original mixers retained the same exact metal work with the only change to switch locations added above the Auxiliary channels on the CMA 10-2DLA, CMA 10-2DLB, and CMA 10-2DLC. Any faceplates diversifying from this metal configuration with more than 3 Auxiliary switch holes between the left and right upper tone controls are not authenticate or original.

 The final and last to be offered in the series was the  CMA  10-2DLC. This mixer is identical to the CMA 10-2DLB with the exclusion of the power switch and a Booth output control added. Bozak was adding the Booth output option in place of the power switch as early as 1977 on special order mixers. This option can be seen on many various models but only the CMA 10-2DLC has the actual numbers for gain level on the faceplate. All other models the factory added this option to only have the word Booth above the control. Faceplates from the factory exist with different lettering or function wording but all have the same metal work as mentioned earlier.

  Also a few CMA 10-2DLM (M for a  mixer factory modified) and CMA 10-2DLO (O for a mixer with customers options) custom built.  Many mixers  have appeared modified, re-worked, meters added etcetera to the original DL series over the years. This is not to say any of these mixers are good or bad only that they were not Bozak factory originals.   

  This is a rare 1979 Bozak factory service bulletin. These were sent to repair centers to make updates or notify them of changes being made to the mixer.  

 This is the optional 225.11 S line card offered in the 1975 owners manual. The card was designed to be inserted as the 3rd line stereo amplifier. It was advertised as 18db but actually had a 20db gain. 

 This was the last owners manual published. It included notes on replacement parts. 

    The 1985 DLB and DLC mixers had inserts added to the manual that explained their added features.