MM Electronics 16 x 4 rare (and old) mixer

[zemobilerec]

Hello !

This is my first here.

Well, as recently send in PM to an user: this can be weird but it is true; a musician trying to get some spares for a MM rare mixer! Found an old post named “ I found an old desk in the shed... ” but not much info about this particular model 4 buss / VUs.

I caught up a 16x4 MM mixer at a collector store and it is in the need of some 741 RCA, some ALPS 100kA 60 mm faders, two 100k (log/lin) pots to get replaced (axe broken at knob but working) and I am willing to know if these items could be still available in order to put this mixer in to original specs?
I sincerely hope you can help me by this, please!

I have suscribe to the site just to contact experts about this inusual console.

[DGL.]

Everything will be available, just maybe from a different brand. For example RS sell 100k 60mm sliders https://uk.rs-online.com/web/c/passive- ... 4291550392 ,

100k pots: https://uk.rs-online.com/web/c/passive- ... 4291550405

and the 741 is a standard op-amp that's been around for ages so is available from many manufacturers.

[Wonks]

The 741 was one of the first op-amp designs and there are drop-in replacements available that are quieter and generally perform better e.g. higher bandwidth and slew rate.

A quick upgrade would be the TL071 for a single 741 replacement in an 8-pin package and the TL072 for a dual 741 replacement in an 8-pin package. There are better op-amps than those available, but I believe most would require some support circuit component changes.

[Folderol]

Yes. The TLx series are pretty reliable upgrades, but a lot of the newer ones have so much gain that you might have to do a fair bit of work to maintain stability

[James Perrett]

There's nothing strange or rare about an MM mixer. They were a very common budget mixer back in the 70s and 80s. The faders and pots are fairly standard and the 741 was probably one of the most widely used op-amps at the time although you can almost certainly do better these days. Their strong point is the gyrator eq while the weakest point is probably their noise.

[ef37a]

Yes, 741s are noisy and they are also just about the only op amp that does not have a good enough slew rate for audio (up to 20kHz)

The TL071 is an ok chip but in the low impedance circuits found in mixers will not give the best noise performance. The NE5534 will be very good for noise but beware, it draws up to 3 times the supply current of a 741. Perhaps use the 34 in critical positions such as summing amps and 071s elsewhere. Much will depend of course on the nature of the existing power supply. There are of course scores of other op amps around but none really any better than the NE5534/2 for audio. Exception, the LM4562 but expensive and I doubt you would hear any benefit.

Op amp decoupling: The usual way is a single 100nF cap across the supply pins. NOT +pin to 0V and another -pin to 0V. Easiest to just tack them back of the PCB. (if not already there!).

Personally I would strip out the 741s and fit Gold plated, low profile sockets but I know some folks are agin'em!

If you have access to a drill press and a suitable soldering iron you can make a tool that will enable you to heat up and whip out the chips with virtually no danger of PCB damage, also vastly quicker than "cut, heat, pick, chuck"

Dave.

[James Perrett]

Just for reference - there's a circuit diagram which is probably very similar to this mixer at

http://www.muzines.co.uk/articles/hot-r ... mixer/6373

which shows that the 741s aren't in a particularly critical part of the circuit. I don't think I'd go replacing them with NE5534s as they are not stable at low gains without extra components.

[ef37a]

Just for reference - there's a circuit diagram which is probably very similar to this mixer at

http://www.muzines.co.uk/articles/hot-r ... mixer/6373

which shows that the 741s aren't in a particularly critical part of the circuit. I don't think I'd go replacing them with NE5534s as they are not stable at low gains without extra components.

Good point James and I really should have advised new OP to get a schematic before even taking a screwdriver to the mixer!

What a strange design? I would either bang the thing onto Ebay or strip it completely and just use the case and meters.

Dave.

[Hugh Robjohns]

Guys, the OP just wants to restore this mixer to its original specs. He's not looking to upgrade or rebuild. He just wants to know where to get replacement parts.

[ef37a]

Guys, the OP just wants to restore this mixer to its original specs. He's not looking to upgrade or rebuild. He just wants to know where to get replacement parts.

Err...WHY?

Dave.

[Hugh Robjohns]

Why not? Each to their own. It will certainly have a character. And Tony really rates them...

[ef37a]

Why not? Each to their own. It will certainly have a character. And Tony really rates them...

Oh well! "Say n'more cheif. Say n'more" if Tony is on board...

Dave.

[James Perrett]

Not just Tony - I still have an MP180 that I like the sound of - especially the eq.

Technically, most modern mixers will be superior to the MM but they are easy to work on and there's no reason not to keep it going because most of the parts are standard and cheap.

[zemobilerec]

Hi,

thank you all for your posts.
I wonder if you know about someone who could be selling the original spares, that is my main question.

I know about 741s and their replacements, but since this mixer will be a monitor mix fixed installation with a Tascam 85-16B 16 track open reel feeding the 16 (line) inputs and a Tascam 234 4 track cassette at the 4-buss inputs/outputs, I am not in an urge to update these opamps. Why ? Tascam 85-16B uses TL072 and 4558s in their dbx cards, and Tascam 234 also uses RC4558P and NJM4560D, so no trying no upgrade to less noisy specs.
This is a project looking for that 'specific' sound that cannot be "simulated" by the new stuff (happily ).
And for all the other DTRS digital and DSD noiseless recorders, another mixer is used, if not that "in-the-box" PCM audio mixwork. So, thank you for all your advises! You are in fine line!

I am willing to find original ALPS faders, because all I find online are 100K B (LIN) only, I will search by those links, thanks. And also the original pots, these 100K are ones with another axe diameter and the original knobs are difficult to find online.
May I get another non-working one just for pieces ?

Finally, I meant "rare mixer" because all I can find on internet are about MP175s and MP180s but nothing about this unnamed model that has got 4-buss outputs and a "record/remix" switch in each of them that allows and inline sort through channel strips 1 to 4. Nice.

It is noisy but that is the point with this (plus than) 40-years-old tape-based setup! The EQ is very musical to my ears.

[zemobilerec]

Just for reference - there's a circuit diagram which is probably very similar to this mixer at

http://www.muzines.co.uk/articles/hot-r ... mixer/6373

which shows that the 741s aren't in a particularly critical part of the circuit. I don't think I'd go replacing them with NE5534s as they are not stable at low gains without extra components.

Yes, I have certainly seen this site and that schematic lets me drown faster into the PCB.
Also I must say that even after all these years after its fabrication and its not so clean external condition when found, it only has got four channels to get repaired and two faders opened ! The rest of the faders are very noisy but I hope they get a clean pass after specific spray product traitment.

So clean inside and clean work !

C.

[Martin Walker]

Just for reference - there's a circuit diagram which is probably very similar to this mixer at

http://www.muzines.co.uk/articles/hot-r ... mixer/6373

Wow - I'd forgotten how many useful DIY eectronics articles use to appear in Electronics & Music Maker!

And I was once the owner of a 16:2 MM mixer for band use, and an 8:2 version for my keyboards

[Arpangel]

Just for reference - there's a circuit diagram which is probably very similar to this mixer at

http://www.muzines.co.uk/articles/hot-r ... mixer/6373

Wow - I'd forgotten how many useful DIY eectronics articles use to appear in Electronics & Music Maker!

And I was once the owner of a 16:2 MM mixer for band use, and an 8:2 version for my keyboards

I’m still after one of these mixers, please, if anyone can help, be much appreciated.

[zemobilerec]

Just for reference - there's a circuit diagram which is probably very similar to this mixer at

http://www.muzines.co.uk/articles/hot-r ... mixer/6373

Wow - I'd forgotten how many useful DIY eectronics articles use to appear in Electronics & Music Maker!

And I was once the owner of a 16:2 MM mixer for band use, and an 8:2 version for my keyboards

I’m still after one of these mixers, please, if anyone can help, be much appreciated.

Hi,

Arpangel, I am not trying to profit this post but if you are really interested send me a PM.

About my MM Electronics 16:4, I do not know the actual model ? Do really care if it has been built from standard and cheap parts, I like the way it sounds for my tape project basically.

Thank you all !

[Arpangel]

AFAIK there wasn’t a 16-4, only a 16-2 and. 12-2.
I’m looking for an original that hasn’t been mucked about with, they are easy to work on and restore, I don’t mind doing that.

[Rob Kirkwood]

No, there were some other versions...

I bought a 4 output group version brand new, pretty sure it was an 8:4 but might have been 12:4. Don't recall any tape returns back into channels, but it did have limiter on each of the 4 outputs (= the reason I bought it).

Unfortunately the limiters were either on or off, with no adjustment, just a switch and led per output group... and, you got a 'crack' on the signal everytime the led lit up - making it pretty useless for what I wanted. I sold it and bought an Allen & Heath 16:4:2 which I kept for many years.

Rob

[James Perrett]

AFAIK there wasn’t a 16-4,

I've certainly used a 4 group MM mixer partnered with an old Ampex 4 track which was the same size as a 2" machine. I think the mixer was very similar to the MP175 with extra routing buttons but we're talking nearly 40 years ago so my memory of it is hazy.

[Arpangel]

AFAIK there wasn’t a 16-4,

I've certainly used a 4 group MM mixer partnered with an old Ampex 4 track which was the same size as a 2" machine. I think the mixer was very similar to the MP175 with extra routing buttons but we're talking nearly 40 years ago so my memory of it is hazy.

That’s very interesting James, I’ll have a poke around the net, and a few old Studio Sound ads!

[zemobilerec]

Yes, certainly my MM is a 4 track studio console.
I have found an ad that listed several models, not found this one ; but there were two 16:4 in that Ad, a MP175 and a MP290 “foldback”.
The model I own has got a foldback level control per channel and PFL as well. May I learn how to upload some pictures here for you to see.

[zenguitar]

Check this very useful link for very helpful instructions on uploading images...

https://www.soundonsound.com/forum/view ... hp?t=75253

Andy

[Arpangel]

Yes, certainly my MM is a 4 track studio console.
I have found an ad that listed several models, not found this one ; but there were two 16:4 in that Ad, a MP175 and a MP290 “foldback”.
The model I own has got a foldback level control per channel and PFL as well. May I learn how to upload some pictures here for you to see.

No please don’t, you’ll only make me jealous.