Vintage Yamaha Amplifiers..

TennesseeOutlaw

I have recently picked up a couple of Vintage Yammy's (M-40 and M-85.) Does anyone have any experience with these amplifiers? I have read nothing but good things about them. Actually, most are stating that the (M) series is the best that Yammy has ever produced. I have a (2nd) system in an entertainment room and it consists of: Yamaha HTR 5890, Infinity Beta 50's, Infinity Beta C360, Infinity Beta 20's, Infinity SW-12, and now the (2) newly acquired Vintage Yammy's. I was planning on using the 5890 as a pre and using the M-85 on my Beta 50's, and the M-40 on my Beta 20's... I have another thread (in the WTB section) for a mono amp for my C360. Russman has given me a few options that I am currently exploring, but I would like to know if the M-40 can be bridged mono.. If so, I think I will pick another one up. If you have any knowledge, ideas, stories, i.e. whatever on the (M) series amps please share. I would like to learn as much as possible about these amps..

Thanks in advance,

Josh

TennesseeOutlaw

Ok, this is EFFIN' HILARIOUS!!!! I just got off the phone with Yamaha. This tech is full of sh%t!!!! I asked him if the M-40 was bridgable to mono, and his answers "NO." I say ok... Second question, the M-85 is rated at 260 wpc, could you tell me what the power output would be if I hooked up my center channel to "speaker b?" He says 260 watts a speaker! I pause, thinking to myself, "a stereo amplifier, third speaker, hmmmm???" So I ask him, well the M-85 has 3 sets of speakers posts, (A,B,C) how many watts would each speaker get if I had (3) sets of speakers hooked up to this amp? He replies, and I qoute, "they would all get 260 watts SIR! This is a very good amplifier!" LMMFWAO OK all, I definately need YOUR help!! Seems like the company that made the dam thing cant help me a bit!!

Josh

heiney9

Yamaha's are not the greatest and they are not the worst either. They seem to unneccesarily complicate the simplist designs and put lots of unneeded parts in the signal path. The seem to put more switches, relays, protection/limiting circuits and do some goofy things in their amps. They also use a lot of hype to name things like Pure Class A, Dynamic Drive, Absloute Linear Amplifier, etc. On some of their pre amps the tone controls are actually fed thru the negative feedback loop (yuck). In some units the powers supplys are usually running at their limit. And in even some units the indicator lamps are part of the protection circuitry so if the lamps burns out the amp will go into protect mode and not even turn on. Stupid to have an indicator lamps running in the same voltage loop as protection ciruitry.

They sound average, but different generations of Yammy's are all over the board as far as build quality. I just recently (Saturday) aquired a Yammy AX-900U integrated which was still built when they had some quality(1987). It weighs in at almost 40lbs and claims 130 WPC @ 8 ohms and it sounds decent, nothing spectacular, but not too bad either. Has a huge tranny as well as huge caps. It needs a cleaning as all the tone controls are scratchy and actually cause drop outs if you move them around.

One thing I noticed is how different the unit sounds when using the CD Direct button. This should theoretically bypass all the switching and tone controls and just use the volume pot, not passive, but still active pre stage. With out the CD direct engaged the sound is very bass heavy, not sure what that is all about.

It's probably to early to tell what this thing is made of until I clean it up and put it in the main system to compare with the Adcom/Nak combo on the harder to drive Lsi-9's.

Overall for a 2nd system unit this should work out quite nicely, especially since it's a hook-up from a local Club Polkie .

H9

heiney9

As far as bridging mono.............very few amplifiers are as good in mono as stereo. And at this price point, none. Based on knowing a bit about Yamaha and their designs even if the M-40 could be run in mono, I wouldn't do it because they aren't beefy enough for it. If it turns out the M-40 can be mono i would absolutely not run anything less than 8 ohms at any kind of high output and probably would even stick to 16 ohms.

H9

heiney9

So I ask him, well the M-85 has 3 sets of speakers posts, (A,B,C)

Output will be decreased because on the Yammy's if you run more than 1 set of speakers they parallel them and that increase's the resistance and will cut output in half (in theory). Not to mention Yammy's have all kinds of current protection circuitry that will absolutely interfere with output if the amp is even slightly over driven.

It's a complicated situation and I'm at work and don't have the time to give a nice detailed explanation. Probably should have left it alone to begin with :eek:

WilliamM2

You may be able to find some info here:

http://www2.yamaha.co.jp/manual/pdf/av/english/SepA/M-85.pdf

You can't hook three discrete channels to it, as there are only 2 inputs, right and left.

Deadof_knight

The yamahas Ive had in the past are stout I have 2 mx-830 and they have 3 pair avaible as far as hook ups the m-85 is stout as well Ive looked atthem and my friend has one, Not sure what the rating is on the 85 but I got my manuals online.

ps .they might not be the greatest but there are far worse out there they got my bang for the buck vote as far as used amps go

McLoki

I purchased an M-85 to run my SDA-1b's in the late 80's / early 90's. (also still have the matching C-85) I thought it was a very good amp that ran the 4ohm (2 ohm at certain frequencies) SDA's just fine. I was very happy with it and considered it a great amp (right up unil 5 gallons of salt water ran into the top of it.)

Michael

mhardy6647

I frankly don't know much about any Yamaha separates except some of their tuners), but they made absolutely superior integrated amplifiers for a massmarket audio company in the latter half of the 1970's. I've owned a CA-610II since it was new. It's been powering my Polk Monitor 7A's since then; an excellent combination IMNSHO.

I recently acquired a beautifully reveneered and refurbished CA-800 (one model "up" and one model year earlier) and it is excellent. The CA-800, as did several of the better Yamaha integrateds of that time, has switchable full class A output operation Not "New Class A", or any of that quasi-class A stuff -- 10 wpc, inefficient as all getout (think: space heater), but excellent, transparent sound. Clean, fast, detailed, and neutral in class AB, too.

I cannot say enough about these amplifiers.

heiney9

I'm a little anxious to hear how this Yamaha AX 900U sounds on the main rig with the power hungry Lsi's. I used to sell this series integrated's as well as the M series amps and pre amps. Didn't think much of them back then, merely run of the mill average against the likes of Nakamichi Stasis, Adcom, McIntosh and Luxman.

It has a massive tranny and caps look impressive. I'll be doing some listening and comparing in the next couple weeks and really see what this thing can do . Either way for the 2nd rig this seems to be the ticket to run my 5b's.

Here are some borrowed nudies

heiney9

I finally popped the top on the AX-900U and I will say the layout is really clean and I'm a little bit impressed with the quality of parts and the detail in this integrated. I still don't like all the switching features, too much going on. I know I'm nitpicky. But there is a very minimum of ribbon cable (only where necessary and in areas of low impact on sound). All wire is 16 gauge and it's run smartly through out and all conncectors to the boards are beefy and well done. There is plenty of room in this monster to work and the chassis is reinforced nicely.

The boards are layed out nicely and marked left channel and right channel (sort of a dual mono type thing). Something unique that I have only seen in my purist Nakamichi pre-amp are copper power rails running down the center of each side of the PCB board from the PS to end of the board (L & R) instead of a pcb copper trace for power distribution. A very beefy and no nonsense approach.

My biggest concern is that the massive transformer gets almost too hot to touch when idleing and the overkill bypass caps are within centimeters and get a lot of heat. I hope they last another 5-10 years. It seems perhaps this isn't an issue because Yamaha seemed to take special care in other area's so maybe they knew what they were doing.

Overall, I'm impressed with the build quality, quality of parts and attention to many details in this unit. Once I get to the controls and get them cleaned and lubbed I'll get my listen on in the main rig with the Lsi's, before returning it to office duty on the 5b's.

I believe this unit is circa 1987.

H9

dkg999

July of 1987 if I remember correctly!

McLoki

I remember my M-85 had a class a switch on it that would run class a up to 30 watts. When engaged the amp would run VERY hot. (as in could not touch the top without getting a burn)

Is it possible that you have a similar switch engaged? (not familiar with your integrated)

Michael

heiney9

McLoki wrote:

I remember my M-85 had a class a switch on it that would run class a up to 30 watts. When engaged the amp would run VERY hot. (as in could not touch the top without getting a burn)

Is it possible that you have a similar switch engaged? (not familiar with your integrated)

Michael

Nope this is definetly a class A/B amp. The heat sinks would never be able to dissipate the kind of heat a class A stage would generate beyond the typical 3-5 watts. 30 watts of Class A is huge, I doubt that it generated that much true wattage in pure class A. I know those generation amps ran in Class A up to a point but is more like 10-15 watts in reality, still pretty cool :cool: .

H9