yamaha pm700 info needed

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fatty

Member
Joined
Jun 3, 2004
Messages
24
Location
Melbourne Australia
the yamaha pm1000 and pm2000 desks are held in high regard by a lot of folks for their transformers balanced discrete class a mic preamps. a lot of people these days use them as a front end for a d.a.w.
does the pm700 share the mojo of these bigger desks? i know it is transformer balanced, but not sure what the topology of the mic amps on the 700 are - any ideas anyone???
 
I did some research awhile back on the PMxxx mixers, and as I understand it, the PM700 (and PM430 and rackmount PM170/180) all have op-amp based channels (Toshiba SIP types that run on bi-polar 22-ish volts) with discrete amplifiers for the gain make-up/output (these are all passive buss designs).

The PM1000 is all discrete class-A, and the PM2000 had discrete mic/line preamps and Toshiba SIP opamps elsewhere (eq, etc..).

All of these used Tamura transformers (Japanese) -- the PM1000/2000 having nice, big trafos, with the smaller desks having much smaller, lower-headroom units. All the reports I've read favor the transformers in the 1000/2000 with less excitement for the others.

Hope this helps.

JC
 
The input channels have a TA7136P single opamps, in a 7 pin in-line package, as the first gain stage, and they're also in the aux in's. echo return, and talkback circuit. They were apparently popular in Japanese hifi gear at the time, and know one has clued me in as to specs or a possible sub. The channels seem okay, but not special. I want to mess with the board before I just canabalize it for the iron and the NE8010O opamps, since there are somethings worth messing with. I haven't gotten a chance to mess with the summing quality, where the cool opamps are, and the bass eq on the channels just sounds great in an enormous 70's dub sort of way. Knowing what I know now, I might have held out to find a local deal on a 1000 or 2000, and gotten a case or two of beer to bribe a crew to move it - the 700 is already huge.

Bear
 
I have a PM1000, and it sounds awesome. I use it on everything with great results. The only thing that sucks is the EQ is limited. There's some info out there on modifying the EQ, which makes it much more useful.

In my opinion, the headroom on the PM1000 is astounding. It can take a lot of volume without distorting. I highly recommend checking out the PM1000. I got mine for about $400 after shipping, and then I put about $200 into reapping it, and I'm very pleased with it. The mic/line amps sound REALLY good. The Hi and Low EQ's also sound great stock.
 
thanks for the info guys.
bear, would it be possible to replace the TA7136P with a discrete melcor. is there enough room in there? or am i just talkin crazy?
i really don't need a desk, especially not one so large, but if i can snaffle it cheap, would it be worth all the hassle to hotrod? would it be easy to work on or is it cramped in there like all the new boards of today?
 
Fatty,

The PM1000 has TONS of space on the inside for modding. I've not witnessed so much real estate on a PCB on anything else I've worked (as limited as that may be). Seriously, there is an abundance of space inside these things. They aren't too big either, but they are very heavy. I think they're around 200 pounds for the 16 channel version. If that's not worth it, then know that the transformers on the PM1000 are supposedly much nicer. I've never heard the 700, but that's the word on the street.

If you can get a PM1000 for under 500 bucks, it would be very easy to rack them up and use them as micpre/eq modules. You could even sell 8 channels raw on eBay and pay for the mixer and the modding like that. You could probably get it so it wouldn't cost a thing. :green: I think it's the best deal in the world. You couldn't build 16 discrete mic/pre eq modules (or even one or two) for that price, and they sound great. The eq is a high quality inductor based design, so just change one cap value, and you can change the selectable eq frequencies to make the eq something you desire. My plan is to actually change the eq frequencies in banks of four. So I'll have four channels of frequencies a, b, and c, and then another four channels with frequencies d, e, and f, an so on. That way I have more choices.
 
Here's a picture of a PM1000 module, to show you how much space there is in these things... LOTS OF ROOM!

full-view.jpg
 
thanks tubejay.
the pm700 is smaller and not modular like the pm1000, as far as i can tell. i'm not sure if it is all on 1 big board or whether each channel has its own board, do you know either way? thanks for the cool pic and info.
 
Hey, just found this thread...
I have a PM430. I had been thinking of building a passive mix buss and I figured that if the circuitry wasn't that hot, a $75 PM430 was worth it just for the encolsure.

Like fatty, I'm also interested to know if there's a way to replace the TA7136P ICs with a dicrete opamp. There's gotta be a way.
I have a full schematic and inside photos I could post later. In the meantime here's an image I found.
pm4301.jpg
pm4302.jpg

A cool package, I think. Each channel has it's own board and there's a good amount of room inside.
...and if you squint, it's sorta, kinda like a yamaha "Melbourne".
 
Does that EQ use inductors like the PM1000? I'm guessing that's just a high and low eq, right? Is it transformer balanced in?
 
No inductors. It's high, mid, low. The mid band is a bit narrow/sharp sounding, the low band is dub-tastic, the high band okay.

All ins are transformer balanced, as are at least most of the outs. The talk I hear is that the PM-1000 and PM-2000 have larger, better quality input iron with more headroom.

Bear
 
[quote author="Bear"]No inductors. It's high, mid, low. The mid band is a bit narrow/sharp sounding, the low band is dub-tastic, the high band okay.

All ins are transformer balanced, as are at least most of the outs. The talk I hear is that the PM-1000 and PM-2000 have larger, better quality input iron with more headroom.
[/quote]

The PM430's 8 channels and Masters all have Hi and Low EQ and there's one inductor. All channels have input transformes and there's two big output transformers on the Masters.

I still wanna get the schematic and inside pics posted.

Bear, you said this has a passive buss?
 
[quote author="jvanslem"][quote author="Bear"]
Bear, you said this has a passive buss?[/quote]

I didn't say that. I'm not sure what bus you speak of on which board.

Bear
 
Sorry for the unfounded accusation, Bear. Here's the quote I must have seen:

[quote author="rascalseven"]I did some research awhile back on the PMxxx mixers, and as I understand it, the PM700 (and PM430 and rackmount PM170/180) all have op-amp based channels (Toshiba SIP types that run on bi-polar 22-ish volts) with discrete amplifiers for the gain make-up/output (these are all passive buss designs).[/quote]
 
Not that it isn't. Just checked my PM 700 schem's, and it does indeed look like a passive mix bus. I just hadn't said anything to that effect yet.

Bear
 
So I finally cracked open my PM 430, which has been sitting out in the garage for some time.

Anybody think the discrete output section might make a nice pre?

I've got the included input trannys and a bunch of cinemag 75101As that I could use if appropriate. For output I'd probably use what's included in the board.

I guess the other option would be to stuff some 312 cards or something.

Any advice appreciated, I'm very green.
 
[quote author="rattleyour"]So I finally cracked open my PM 430, which has been sitting out in the garage for some time.

Anybody think the discrete output section might make a nice pre?

I've got the included input trannys and a bunch of cinemag 75101As that I could use if appropriate. For output I'd probably use what's included in the board.

I guess the other option would be to stuff some 312 cards or something.

Any advice appreciated, I'm very green.[/quote]

I'm a novice too, but from what I know I think that the two master channels have potential to make nice pres (with discrete hi/lo eq too), but you may need some additional components besides an input transformer.

I also have a pm430 (that I gutted). I'm considering using the Yamaha NE80100 opamps and the PM430 input and output transformers in a JLM 99v pcb. I checked with Joe at JLM and he's says it'll all go together nicely without substituting any components.
 
That sounds like another cool option, thank you.

In the meantime...

I wonder what I would need to use them as is though ? Obvioulsy you'd need some way to control gain.

Also, would it be better to cascade the two channels together somehow to make one pre?

So many questions.
 
[quote author="rattleyour"]
I wonder what I would need to use them as is though ? Obvioulsy you'd need some way to control gain. [/quote]

Just keep the fader attached. (though I forget if it's a trim or gain control)
 

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