Ampex MX-10, MX-35 As A Possible Model For Group Project?

I'm curious if people here think a small Tube Mixer based loosely on an Ampex MX-10 or MX-35 would be a good group project or not?

Here's a link to the Ampex tube mixer schematics and parts lists:


http://ftp.ampex.com/ampex/manuals/audio/mx35man/

It's really a clever design, particularly the summing amplifiers, which have a secondary feedback connection from the cathode of the 12AU7 cathode follower back to the screen of the EF86.

If anyone decides to build it, though, for goodness' sake use something besides the tiny Beyer input transformers Ampex used. Unless you really like saturation, of course.

Peace,
Paul

The predecessor to the MX10 was the SA3671. Here is a schematic. It uses everybody's flavorite transformers HA100X and HA133's. I was thinking about building a single channel just for jollies. I really like the MX10's sound.
-Richard

I've been looking at that one lately too. I'd be interested in knowing if the L/R/Center switch could be made into a pan pot without too much trouble??? I've also heard that these can sound much better with a Jensen JT-115K-E or similar input transformer in place of the Beyer.

Steve

The panpot would have to be of very high impedance, and that brings up a host of other problems.

The MX10/35 is a nice simple mixer design. But it might be too simple for what most recordists want to do these days.

Well then maybe with some tweaking and creativity applied to this simple design it could be made into something that was very useful in today's world.

Ampex MX-10's and 35's are still found and being used at studios, I dunno if they have been modded.

I revamped a MX10 about a year ago for my friend Mr. Leary's ProTools studio. It's his "dirtying tool". It's an adequate "tape saturation simulator". He uses it a lot on kick and snare drums. I let him have my last pair of Amerex EF86's cuz it had 2 already and the other 2 were like a no name brand and a Valvo. It was just too pretty when it was done to not have matching tubes.

This is probably a dumb question but how did one add a panning pot to a tube console or tube mixer back in the day? I can see where the impedence from the tube's plate going into the pot will be high. Just wondering how this was addressed. I can see this would be a similar problem in that Neve tube mixer schematic floating around here.

Also, what is an ideal range of impedence for a pan pot's input if there is such a thing? Thanks.

Steve

Wish I knew the panning answer.

This Ampex-like mixer is beginning to look like it really may turn into an interesting project.

Lets compare it to the Neve tube mixer schematic.

Can someone post the Neve schematic.

[quote author="guitarmaker"]I've also heard that these can sound much better with a Jensen JT-115K-E or similar input transformer in place of the Beyer.[/quote]
No! Get the Reichenbach RE-115K-E from these guys instead. Reichenbach designed the thing. Jensen just licensed the design and sells it for way too much money.

No! Get the Reichenbach RE-115K-E from these guys instead

Click to expand...

From Cinemag? I can`t find that model in the website...


Synthi

[quote author="synthi"]From Cinemag? I can`t find that model in the website...[/quote]
E-mail them. IIRC, they'll build most (all?) of the old reichenbach designs upon request. The owner is Ed Reichenbach's son.

Thanks :grin:

Synthi

Ok, do we have comments comparing the Neve vs. Ampex designs?

[quote author="jcb"]Ok, do we have comments comparing the Neve vs. Ampex designs?[/quote]

The vast majority of Neve desks are of solid state design and hence have circuitry of "low/medium impedance" design, vs the tube Ampex mixers, where everything (including the output stage) is of high impedance design.

It's comparing apples to hockey pucks <g>

Bri

Hmmm, sorry I thought that link was supposed to be to an early Neve Tube Mixer (or maybe something he modded), was I wrong about that?

There is an early Neve 10 channel tube mixer schematic floating around here. From 1961 or something like that. A guy on the forum mentioned that he made a single pre section of the mixer and liked it a lot. I re-drew part of it thinking I'd try to make at least a single pre section myself. It's different from the Ampex but having never heard either I'm not sure how they compare sonically.

Steve

Thanks for clearing that up.