Yamaha PM-180 anyone?

I have one en route to me as we speak. Got it for $50 in great shape. Here's the catch: I have no idea what this thing is capable of.

Does anyone have any experience with this unit? How does it compare sonically with the PM-1000? Is it discrete? I was told that it has Tamura transformers throughout. Can anyone confirm?

If the pre's are any good, I'd like to add direct outs on all channels, otherwise, I'm scavenging every part I can for DIY.

I'd love to find a schematic, so if anyone has one, please let me know.



J.

Hey - I'll share the little that I've been able to figure out - I have a Yamaha M916 that's of the same vintage.

Here's a link to the owner's manual:

http://www2.yamaha.co.jp/manual/pdf/pa/english/mixers/PM170E.pdf

The manual says that the "PM180 is equipped with transformer-isolated XLR connectors", which makes me think that there are transformers on the XLR ins.

The manual also says that the "A" outputs (left / right) are transformer isolated.

When I was doing google searches on my M916 I read that the PM180 is not discrete, although I've never seen a schematic or looked inside one. I read that the PM180 uses mostly Toshiba TA7322 op amps. Do a search of the forum for more info on that op amp - word here is that it was not all that bad.

The transformers in my M916 are Tamura, and I've read that most of the transformers in these old Yamaha's were Tamura.

I'm chipping in what I know 'cause folks here have been pretty helpful with info on my old board. I'm definitely a novice, though, and what I've posted here is all I know about your PM180. Good luck with it!

dave

Somebody is selling a PM180 service manual on eBay for 20 bucks...

Peace,
Al.

Hi Jason,

Welcome on the board! :grin:

... and check your post :wink:

Same answer as the one I gave you over on the TapeOp message board... :twisted:

My guess would be op-amp based circuitry, based on the power supply hookup diagram in the users manual.

I just downloaded the PM170 manual from Yamaha's website. This covers the PM-170 and the PM-180. It doesn't include the schematic. I was surprised, because it's a lot like the PM1000 manual, which is also available on their website and does include schematics. Follow this link and enter PM180 in the search field:
http://www.yamaha.co.jp/manual/english/index.php

I used to have four PM-180's. Yes, there's a Tamura transformer for each mic input and the main outs, but these are all different than the ones you'll find in other, bigger Yamaha consoles of the same vintage.

I've never done an A/B between the PM-180 types and, say, the PM1000 or PM2000 types, but I can say that they are tiny compared to the ones in the bigger boards. Same 1:3 ratio, however as the larger boards.

The mic pre's use a Toshiba 7-pin SIP IC package that is capable of 24-volts, though the PM-180 (and 170) use bi-polar 22.5 volts. The sound interesting, and actually compared pretty nicely to a class-A Neve in size, but the sound was a bit more smeared somehow... didn't maintain its authority when placed in the mix. My guess is either cheap transformers or cheap op amps in the channels.

Also, the eq on the thing is interesting as it is a 2-band (hi/lo) eq with fixed frequencies, but they're not shelving filters, they're peaking. Also, the HF band uses a real inductor and actually sounds pretty cool. I imagine with some creativity and elbow grease you could make an interesting and useful device out of it. I thought about it, but decided I just didn't have the time and sold them off.

The best thing about the PM-180/170 is the two discrete output amp blocks, parts NE80100, I believe. These are the line-level version of their discrete op amp of the time. Both this amp block as well as the mic version (NE80200) are used in the PM2000, and many people have spoken about how good that board sounds. Different (bigger) transformers in the PM2000, however.

It may not be a 2520, but you get two for your $50 purchase price of the PM-180, and that's a lot cheaper than a pair of 2520's (if you can find them) for $75 each and up....

Also, the Yamaha amp blocks can run on +/- 24 volts, while the 2520 tops out at +/- 20 volts.

The Yamaha amp blocks share the same pinout as the 2520 (and just about every other discrete op amp from Hardy, Jensen, Melcor, Inward Connections, Forssell, Millennia, etc...) I still have a couple of these amp blocks an intend to try them in a couple of channels of Fred Forssell's opto compressor when I can find the time.

Peace,

JC

Same 1:3 ratio, however as the larger boards.

Click to expand...

I havn't measured them myself. But in the PM1000 schematics the input and output transformers are said to be 600:600

[quote author="rascalseven"]
The Yamaha amp blocks share the same pinout as the 2520 (and just about every other discrete op amp from Hardy, Jensen, Melcor, Inward Connections, Forssell, Millennia, etc...) I still have a couple of these amp blocks an intend to try them in a couple of channels of Fred Forssell's opto compressor when I can find the time.
[/quote]

Wow! That's invaluable info!

Thanks everyone for the warm welcome and thoughtful replies. I'll be spending a lot of time around here.

I have both PM1000 parts and a PM180. I have added direct outs using spare PM1000 (tamura) output transformers. It works.
The stock outputs on the PM180 are actually bigger transformers but they arent shielded and look more like small tube amp transformers!
The mic pre is an IC but has a discrete output stage? It uses a smaller transformer but is a similar same turns ratio as the PM1000. 3k/600. The discrete output looks like a baby brother to the PM1000 base amp circuit. The same one that they used for the mic amp in the PM1000 show sup as a line amp and summing amp. Its the same arrangement of 5 transistors and a diode with a couple caps in the signal path.
I have seen elsewhere hat someone replaced the 7 pin IC with an 8 pin BB ic. Not sure of the part number but he said that since only 7 pins of the BB were active it was cinch.

if it can still help ...

It is helpful. Thank you.

Contact Yamaha service, they were very helpful when I was looking for schematics for the pm700.  Its probably pretty close to your 180, although differs significantly from other info posted in this thread.

For instance the pm700:
Channels use Tamara transformers 600:3k (pm told they're smaller than the pm1000 trafos).
Channels use ta7136 op amp.  7 pins in line.  Runs on +/-15.
Master section uses the Yamaha potted discreet op amps running at +/-22v.  Im replacing mine with some hairball audio kits as soon as they arrive

Direct outs are possible and as easy as a jack and a small resistor.  I tapped mine off the monitor 2 section, just after the cap on the output of the mon2 op amp.  Tonnes of gain, I'm not bothered by it being unbalanced.

High eq is inductor peaking.  Sounds better after replacing the 22n cap with polypropylene.

Actually the whole thing sounds better after replacing all the caps both el and ceramic with Panasonic's and c0g/polypropylene, as well as changing the transistors for 2sc2545.

Post the schematic when you've found it!

Pretty close but the low eq is inductor peaking and the high eq is RC shelving.