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What to expect from a recapped M-45?

WannaBeHiFi

WannaBeHiFi

Active Member
I read an article once that left me rather impressed by the quality that went into the M series amps back in the day. Yamaha kinda had a chip on their shoulder and wanted to make a point.
Eventually I acquired a M-45 in quite good condition. But as I learned more about vintage equipment it became apparent that the nearly 40 year old electrolytic caps are way past their expiration date. Well, If I'm gonna rebuild the M-45 I have to have something to listen to.... Which brings me to this discussion. Since I now have something to compare the M-45 to.

What I had: GR Research X-LS Encore speakers. M-45, C-85, Phono, Bluetooth from I Phone or PC. But I was not happy with the sound. I was not hearing the soundstage imaging I had hope to when I built the speakers. I knew BT was part of the problem, I suspected the M-45.

The C-85 died. For a while I just ran the BT direct into the M-45 and backed the gain way down. Which made me rethink the whole concept of what a pre-amp actually does. Though I do miss the Yamaha variable loudness.

Change 1: I replaced BT with a WIIM mini streamer. < $100 Noticeable improvement.
Change 2: I added a SMSL SU-1 DAC. < $100 Noticeable improvement.
Change 3: I replaced the M-45 with a Aiyima A07 Max amplifier. < $100 Noticeable improvement. Now I'm hearing a bit of a sound stage. Keep in mind my room or speaker placement hasn't changed. What I lost was, bass response. The M-45 delivers bass with an authority that the Aiyima lacks.
I've been listening to that for the better part of a year.
Change 4: Recently, I replaced the stock op amps on the Aiyima with Sparkos. $150 WOW! Noticeable improvement. Now I've got sound stage detail I've never heard before!
Example: David Grissman Kaleidoscope F5. I've never heard so clearly defined in space two mandolins, Dawg on the R, support L. Two violins, Lead on L, support on R. A very sweet guitar right in the middle, with a bass behind the guitar.

I gotta whole bunch of music I gotta relisten to. How exciting!

Here is my dilemma. An inexpensive chifi amp sounds better than my nearly 40 year old M-45.
Now the signal from the Streamer>DAC> amp did not change. The Aiyima already sounded better than the M. THEN the Sparkos op amps extracted more resolution and detail from that signal.
Since my only listening experience is with an OLD M-45. How might a re-capped M-45 sound with that same input? How much of that resolution and detail that he Sparkos revealed might one expect a restored M-45 to deliver? Will a restored M-45 deliver that layered soundstage that the Sparkos upgraded A07 has exposed? Is the recap worth it?
 
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This is a very hard question to answer, in my experience from the amps I've recapped, I almost immediately noticed an improvement to bass response and clarity. I know a lot of folks say that the highs are improved but I frankly turn my highs down cause they hurt my ears.

I would say that if you are happy with the Chifi amp, save the restoration money to spend elsewhere. If you feel and attachment to the Yamaha get it rebuilt, I love a good Yamaha and do also love the variable loudness control.

At the end of the dat the way an amp sound comes down to personal preference anyway, go over the options you have and see what appeals to you the most.
 
avionic said:
What did you do with it?
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Mornin' Avionic. Currently C-85 is sitting atop the M-45 looking good and filling in as a dust shield. One thought was to fix it, but it's been suggested that may not be the best place for the inexperienced to start. So the C-85 is in limbo. Really, in terms of usefulness or convenience, the WIIM functionally replaces the preamp.
 
WannaBeHiFi said:
Is the recap worth it?
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Yes. Power amps like the M-45 are the ultimate learner piece if you have soldering skills. And less cost if ya go the stereo shop route. Much easier to work on than the C-85, 62 caps. Less than 30 caps in the M-45. Guessing 30 cuz the bigger brother amps had 30ish caps but haven't owned an M-45, disclaimer.
 
I just recapped an M-65 and while I can’t say much difference in sound stage was noticeable, the highs def cleaned up and more detail in the midrange. I currently use it with a cx-830 pre I recapped as well and the combo is pretty dang impressive especially for vinyl. I use 2 subs in stereo so can’t comment on the differences in lower frequencies.

I def think it’s worth a recap and was fairly easy to do. Aside from the big 4 filter caps, that takes some tinkering to get replacements to sit right on the board and be secured and everything. Also consider swapping out the speaker terminals while you’re in there for newer style ones. They were super easy to do on the 65.
 
Soundscape said:
Yes. Power amps like the M-45 are the ultimate learner piece if you have soldering skills. And less cost if ya go the stereo shop route. Much easier to work on than the C-85, 62 caps. Less than 30 caps in the M-45. Guessing 30 cuz the bigger brother amps had 30ish caps but haven't owned an M-45, disclaimer.
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I most definitely qualify as a learner....
 
It's been the same old story for me going on 8 years now regarding repair of these fine Yamaha pieces. Not a sensei yet but working on it.
1. Corrosive glue
2. Aged electrolytic caps - if ya catch them before cascading failure affecting semiconductors
3. Light solders

Remedy that stuff...you'll unleash the power.

The worst solders on every piece in my stash were the jumpers at the output transistor area. Edge of the main board.

Enough about me. Tons of good old threads here but ya gotta dig. Good luck on your journey.
 
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WannaBeHiFi said:
Mornin' Avionic. Currently C-85 is sitting atop the M-45 looking good and filling in as a dust shield. One thought was to fix it, but it's been suggested that may not be the best place for the inexperienced to start. So the C-85 is in limbo. Really, in terms of usefulness or convenience, the WIIM functionally replaces the preamp.
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C-85's are not that tough to work on. Very little glue damage usually. Dirty switches and controls and some cold solder connections. Usually :biggrin: .

C-85 was TOTL back then. Worthy of a resurrection. :thumbsup:
 
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C-85 like the C-70 has inverted outputs. I really like the Continuous Variable Loudness of the C-85.
 
My C-85 (C-80 honestly but same deal) wasn't affected too bad by the corrosive glue around the heat sinked regulators. That's more of an issue when dudes stack that pre-amp right on top of the power amp ignoring the 4 inch clearance recommended in the user manual. Heat melts the glue toward a subsequent shitshow...it's an old story in this forum. But...
The main problem on mine was the glue area regulator solder points cracked/intermittent open from time & heat contractions.

Esoteric Redneckisms
Hobbyist Jones
 
avionic said:
C-85's are not that tough to work on. Very little glue damage usually. Dirty switches and controls and some cold solder connections. Usually :biggrin: .

C-85 was TOTL back then. Worthy of a resurrection. :thumbsup:
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I disseminated mis-mal-dis-information. The pre is actually a C-65
 
The C-65 is a worthy control amp. And I am rather fond of Yamaha's variable loudness, especially since I listen at relatively low levels due to low WAF. (Wife acceptance factor).
Running phono through the WIIM sounds fine, I don't listen to a lot of vinyl. But I think it would be more appropriate to put phono back on an analog signal path.

Till then I want to focus on restoring the M-45 to it's former glory. I've got other projects and fall priorities to deal with first.

The only way I'm going to satisfy my mental itch to compare the sound of mid-80's analog power to this current Class D Chifi setup is to restore the amp burn in the caps and give it a shot. For the $ invested in very inexpensive gear I'm very pleased with sound. But it was the Sparkos upgrade that really opened things up. I'm getting a kick hearing details I've not heard before.
The recent upgrade demonstrated that at least some of my recordings or files contain enough data to project a soundstage. I've been working to optimize speaker placement and such in hopes of hearing said soundstage. The Sparkos upgrade opened up that soundstage and clarity a lot.

Now that I've got a baseline for comparison. What will I get when I replace a Sparkos upgraded Aiyima amp with a fully serviced M-45? Hmmm... Only one way to tell.
 
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