Datamix Clark M968-A Mic pre

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Chrome Heart

Well-known member
Joined
Apr 22, 2008
Messages
375
Location
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Hey all.
I have a Datamaix M968-A module with mic pre and "toggle switch - slider" EQ. Dated 03/1969 and very similar to the Electric Lady console. Id like to rack it but I have zero info on this module. Does anyone have anything they can share? I really need power and audio I/O information and maybe a schematic. Anything will help. Thanks
 
sorry I can't be of more help--try to trace it. part#s, polarity of caps, diodes, etc can all be hints...look at other gear from that era.
 
somewhere .................I have a bunch of datamix schematics
I'll have a look but it becomes a huge sorting & reorganizing job
 
That looks like the IC/BJT hybrid amp block. The middle section (closest to the row of eq caps) is for the preamp. You can pick up a pre-amp out following the large electrolytic (500uF or so). The next section to the left is the eq amp and the one to the far left is for the cue send. You might need to wire a jumper from the pre out to eq in, unless it's already been done, to make it a full channel strip. The eq switch is where I picked up the module output. I installed 1:2 Jensen OT that I had laying around. I used the 3 rail psu & go-between from JLM Audio when I racked mine.
 
Denyle Guitars said:
That looks like the IC/BJT hybrid amp block. The middle section (closest to the row of eq caps) is for the preamp. You can pick up a pre-amp out following the large electrolytic (500uF or so). The next section to the left is the eq amp and the one to the far left is for the cue send. You might need to wire a jumper from the pre out to eq in, unless it's already been done, to make it a full channel strip. The eq switch is where I picked up the output. I installed 2:1 Jensen OT that I had laying around. I used the 3 rail psu & go-between from JLM Audio when I racked mine.

Thanks. Ill investigate that. Go between also sounds like a good idea. Is the Jensen tranny absolutely needed? Do you remember the model?
 
OT not needed, but the output will be low and unbalanced. I don't remember the Jensen used, probably a 123-A. I don't know what, if any, was used originally. That might be worth investigating. Maybe get a Ed A 2503 from Jeff since the basic topology is similar to API.

Here's the BJT version amp, redone on perfboard in a 2520 footprint. I use it in a VP-26 for really old school sounding guitars.
opamp01.jpg
 
Well I think Ive found the mic input,(circled in yellow) and Im getting a signal at the EQ switch (circled in blue). But the pad seems to have no effect on the signal when I turn it. Also I dont see a 500uf cap anywhere. Highest seems to 100. All the electro Spragues ???. I have 3 legs of power going to the unit @16v. EQ seems to have no effect on the signal either.
 

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  • Clark Datamix.jpg
    Clark Datamix.jpg
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Well, I found this old pic of two side by side. The one on the left is discrete, has switches for pad and gain. The round metal can in this case is a dual transistor. If you stare long enough, you'll notice it has one more transistor than the one on the right.

The right one has a gain pot and the round metal can in this case is a opamp. IIRC, this one was modified when I got it. It's been years since I messed around with these but maybe you can figure out something from the pic. It looks to me like the eq out was wired to the cue send pot and you can follow that wire back to the cap (ie amp block out) and infer the same for the mic amp section.

34063d1176500184-gutz-ddmm01.jpg
 
Thanks for the photo. I have noticed that the "line" wires have been snipped on the module I have. It looks like someone tried to mod it at some point. A schematic would now be really helpful.
 
Uploaded all the docs I have to Tech Docs section of GDIY.  Historical info, technical info, partial schematics...
If anyone has files from the link above, please add it to the community chest - Wayback Machine could not find it.
 
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