Tascam M-___ Story...

Wellllll...

For the first time in just about 9 months the Tascam M-__ mixing console is housed indoors. In that time its been moved 4 times and lived for different periods in unheated non-insulated or air-conditioned spaces like a solarium, a shop, and a garage. I think it has survived its travels and dwellings unscathed except for a small nick in the wrist-rest upholstery...maybe a small dent or scuff on wood trim. Biggest challenge now is to re-trace my steps and try and remember where I left off.

The master module is currently a basket-case. I know I was having trouble with sputtering/popping in the headphone amp, and popping when engaging the MONO, DIM, and MUTE functions for the CONTROL ROOM output...the suspect was an array of JFETs that is repeated in many areas in the master module and in the I/O modules...the array makes an analog switch and IIRC I was going to shotgun all of them. But I know I was also in the midst of replacing/upgrading some key opamps in the I/O modules (in part because I had finally found the cause of an aggravating oscillation issue, but also "upgrading" some key stages), and I don't know where I left off with that, and I was doing some of the same in the master section...and likewise don't remember where I left off there either...and there was the headphone amp problem. I vaguely recall thinking I was going to have to fabricate some extender cables to be able to have the master section fully interfaced with the motherboard while out of the frame, but I can't remember exactly why. And I also recall I had spent a fair amount of time relocating a *really* janky opamp circuit on one of the master section boards to a more proper install in a vacant DIP-8 site on the same board (the IC, caps and resistors were hanging off the back side of another IC like an electronic granola-wart cluster...pure prototype kludge)...BUT...can't recall if that was all wrapped up or not. I recall having some trouble after the mods.

I know I have notes somewhere but I haven't found those yet with all the moving this last year. And I also know I have at least 3 collections of new and/or spare parts that had been gathered together for all the above work but I don't yet know where those are either. And hopefully when I find those I'll also find the hardware and cosmetics for the basket-case master section (screws, knob and switch caps, etc.)

I found a whole bunch of email threads with a friend of mine from 2014 that will be like a trail of bread crumbs for me and hopefully help me refresh my memory.

So close, yet so far...when I was reinstalling the I/O modules back in the frame last night after moving the frame into our office/music room, I had a flashback to...2008? Really?? Will it really be 8 YEARS this year since that cannonball run down to Burbank and back to snag this console?!? :eek: Anyway, as I put module #1 in last night I remembered...allllllll the mouse pee and poo that was all over everything in the back corner of the console when I got it...all the broken stuff...it was really neglected-looking. And no power supply at all. It is the pinnacle of my sweetbeats-edness with the cosmetics all done (including the custom solid walnut wood trim, paint touch-ups and polishing...added color coding of switches and knobs), and inside 100% recapped, pots and switches and boards cleaned...power supply rebuilt and upgraded...ground plane re-engineered...so many small repairs and upgrades to remember. Need to get the last bits done on the I/O modules (the opamp and JFET replacements), and figure out where I'm at with all the stuff on the master module.

It'll get done eventually.
 
Good you're back on an epic project. I always like these. It was your 520 thread that got me on this forum to begin with. :D

Now shouldn't this very thread, that is at 65 pages be of some help to you? At the very least jog some memory?
 
RFR said:
Good you're back on an epic project. I always like these. It was your 520 thread that got me on this forum to begin with. :D

Now shouldn't this very thread, that is at 65 pages be of some help to you? At the very least jog some memory?
Click to expand...

Oh I *know*...it SHOULD! But I read through all of 2014 and unfortunately it details what I was most recently *struggling* with, but not the nuts and bolts of how I addressed or was planning on addressing each of the issues...and I didn't even capture all of the issues. It was like a bad plumbing failure when I got into the master module...you know...shutoff valve is leaking...go to replace it, the nipple breaks off, then when you finally get the remains of the nipple out of the elbow you realize your galvanized riser pipe is almost completely occluded with corrosion...I was on the home stretch doing the comprehensive function testing when the oscillation issue arose and things kind of unraveled from there I recall, and I know I was much more focused on figuring stuff out than I was documenting in this thread what was happening!
 
Hah!

Found all the bits and pieces...new parts, spare parts, notes...everything is together except the power supply is still out in the shop, but at least I was able to eyeball that. ;)

Here it sits, with matching dog!

image.jpeg

image.jpeg
 
Cool. You got it all in one place. For some reason, previously checking the thread, I always thought it was a much bigger board. Despite size, I bet it's still quite daunting.

Good looking pooch too. :D
 
Well, IIRC, I think the footprint of the console is 40"W x 38"D which is pretty big for a 12-channel 8-buss mixer. And I think I weighed the empty frame once and it was 80-90lbs unloaded...think the whole thing loaded is around 150lbs. There are much bigger heavier mixers, but again that's a pretty good chunk for a 12-channel board. The double-wide modules *are* a little daunting to navigate...if you're used to being able to grab 6-8 faders with a hand and slide 'em, that's not happening here with the M-__...maybe get three at once if you're lucky.

And pooch is a complete gem of a dog. :D
 
So for perspective, the M-__ is just shy of the same width as an M-520, and about 6-7" deeper, and quite a bit taller...and weighs 40-50lbs more.
 
sweetbeats said:
So for perspective, the M-__ is just shy of the same width as an M-520, and about 6-7" deeper, and quite a bit taller...and weighs 40-50lbs more.
Click to expand...

No wonder TASCAM never went forward with production on it! They could only fly one or two over at time without overloading the cargo hold! :D



Cheers! :)
 
So it would appear that this M___ console is indeed a prototype for the 512 and 512 consoles. On the production models they pack more channels and features in a similar size footprint.

Looking through the thread, I came across your son setting up levels. So it would seem the board is at least partially working??
 
Well at the moment its not...with the master module out. :D But the bottom line is it is essentially 100% functional, I've just been chasing down refinements and addressing some original design issues.

And yes it is a prototype for the M-50, which preceded the M-512/520. The M-__ is like a missing link between the Teac Model 15 and M-16 mixers and the M-50/M-500 series...has the motherboard and and backplane design of the Model 15 and M-16, but the cosmetics of the M-50/M-500 series...electronically the mic amp is similar to the M-50/M-500 series, and the eq section is really close to the PE-40 rack eq channels (but the hi and lo bands are fixed Q). Big difference between the M-__ and all the other models above is it is a true inline console. And it has a really comprehensive independent stereo monitor buss, and tons of mute and solo points...plus configurable global source switching which can also behave like mute groups. Lots of inputs...1 mic amp and two line amps per module each with their own level control and can be independently and simultaneously sourced, so if you needed to you could mix 36 inputs. Oh wait...there's a pair of routable returns on the master module...38 inputs. Whoops...forgot about the two stereo "EXT" inputs on the master module too...42 inputs. Oh shoot...maybe I should count the two phono preamps too...46 inputs. And 12 of the meters can individually be configured to follow the primary input that is selected on its corresponding channel module, OR the corresponding group output (which is subgroups 1-8 on modules 1-8, and aux 1-4 on channels 9-12, so you can individually check group or aux master levels), OR the output of the monitor channel on the corresponding strip. And then the master meter pair can source the stereo buss, or the monitor buss sum. And there are more bells and whistles too. Lots of patch points like the M-500 series.
 
RFR said:
You know what I have to say to all of that??

DAMN!!!

:D
Click to expand...

I concur...!

Sorry to drone on...I think I've probably conveyed all this info somewhere earlier in this thread (probably more than once), but I get excited just talking about this mixer...

I was looking at the control surface again and reminded of other neat-o features...scans of the channel and master module dress panels and backplanes (jacks) are below...

I mentioned above you can simultaneously source all 3 of each of the 12 channel module inputs at once for 36 inputs; the way you do that is source the mic inputs as the primary inputs for each module, source LINE 1 in the MONITOR buss on each module and engage the MONI TO STEREO function in the monitor switchrack (the mic input is automatically routed to the STEREO buss as the main input of the module...the MONI TO STEREO sums the output of the MONITOR buss on each module with the main input of the module to the STEREO buss...so far we have 24 inputs summed to the STEREO buss, each input with its own level and pan control). To bring in the last set of 12 inputs we have to sacrifice 2 of the 4 AUX busses, and the ECHO RETURN 1&2 busses on the master module. AUX 1&2 is setup on the control surface as a stereo buss (with stacked level and pan controls, as opposed to two stacked level controls like for AUX 3&4)...let's use AUX 1&2. So on each channel module we source AUX 1&2 to LINE 2, and take the output of the AUX 1&2 stereo buss sum and patch those to the ECHO RETURN 1&2 inputs on the master module. We then route that to the STEREO buss. Now we have all 36 inputs summed to the STEREO buss, each of the inputs has independent level and pan control, we still have 2 AUX busses at our disposal and haven't even touched any of our 8 PGM groups. And it is possible, via the SOLO and MUTE controls available on the channel modules to isolate any of the 36 inputs in-place, and if needed it is possible to mute and solo the different input types (i.e. mic, LINE 1, LINE 2) in groups. Yes we are limited to only 12 EQ sections, but those 12 sections can be applied to either the main input (the mic input in the case), OR the MONITOR buss (LINE 1 in this case) via the EQ TO MONI control in the EQ switchrack, so we have some flexibility there. And I forgot to mention earlier the EQ can be bypassed altogether and ALSO includes one LPF and two HPFs per channel (which remain live even when the 4 EQ bands are bypassed).

Does the above scenario make the M-__ a powerful 36-channel mixer? Nope. But it *does* demonstrate just how powerful and flexible of a 12 x 8 mixer it is. If you use it as a 12-channel mixer you can have 36 inputs permanently connected and be able to easily source, route and shape those 36 inputs with ease from the control surface; to be able to mix and shape 12 main inputs and independently and flexibly monitor the others. Its really kind of like a 12+12 x 8 x 2 mixer with 4 AUX busses with an embedded 12 x 2 mixer that is interlaced...it can source any of the inputs and can be summed or be independent...like a powerful matrix mixer.

Another way the multiple inputs can be used: one could source LINE 1 as the main input, and LINE 2 as the MONITOR input, pan LINE 1 hard left using the STEREO PAN control, and pan LINE 2 hard right using the MONITOR PAN control, then by utilizing the MONI TO STEREO function in the monitor switchrack sum the MONITOR source to the STEREO buss...voila, each of the 12 channel modules can be a line-level stereo module.

We haven't even touched the wonderful kinds of things we can do with the REMOTE global source-switching control section.

Here is the channel module (i.e. "I/O MODULE") control surface and backplane...rotary controls with a grey dot in the middle are stacked controls:

input_module_cue_sheet.jpg


input_module_jack_plate_(small).jpg



And here is the master module (i.e. "CONTROL MODULE") control surface and backplane...again, rotary controls with a grey dot in the middle are stacked controls:

control_module_cue_sheet.jpg


control_module_jack_plate_(small).jpg
 
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Your writeup, I'm gonna have to read the that about 7 or 8 times to wrap my head around that one. :D
I'm still exploring routing capabilities on my 520

Btw, quick question. The 520 8 buss inserts. Those are pre- fader, right?
 
sweetbeats said:
No I did those years and years ago...actually used a large flatbed scanner.
Click to expand...

I had thought so but didn't think they made flatbed scanners that large! I had a 14 x 9 inch HP scanner at one time but it died on me. I'm assuming the one you used was larger then that.

Kudos for making use of that! :)



Cheers! :)
 
The Ghost of FM said:
I had thought so but didn't think they made flatbed scanners that large! I had a 14 x 9 inch HP scanner at one time but it died on me. I'm assuming the one you used was larger then that.
Click to expand...

It was 11 x 17! ;) That's also what I used to scan in 100s of pages of foldout schematics from different manuals...much prefer not having them chopped up in the scan.
 
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