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Yamaha M4 power amp

bob06 said:
Avionic's has tested the M-4 at 150+ watts. :banana:
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just have a question for Avionic if he chimes in; someone pulled the two rear output transistors on one driver board and was running it like that. I was considering buying it before I noticed this. It was showing output on both sides and power meters working but clipping light wasn't working on channel with missing outputs. Is this worthwhile for restore or has the damage already been done? I know this is not enough of the picture to say, but it looks like it fell into the wrong hands.
 
I also have 4 and I'm using 2 all bought used. One has been on 7/24 for 10 years. Yours looks very clean. Some of mine look like they've been kicked around a bit. All mine spec and sound good. Mine seem bulletproof too. I'm always looking for an excuse to recap them but they just sound so good that I've left well enough alone. The bias pots get a little sticky, the speaker connections are a royal pain and the front panel lights often burn out. However the front panel lights are so relaxing and so easy to look at (compared to modern LEC lights).

They really work well with my NS1000s (I really struggled finding them an affordable amp) and my power hungry B&W 805Ms. My advise to anyone who is amplifier challenged is to try the M4.
 
tonefoto said:
just have a question for Avionic if he chimes in; someone pulled the two rear output transistors on one driver board and was running it like that. I was considering buying it before I noticed this. It was showing output on both sides and power meters working but clipping light wasn't working on channel with missing outputs. Is this worthwhile for restore or has the damage already been done? I know this is not enough of the picture to say, but it looks like it fell into the wrong hands.
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The missing parts is a good angle to dicker a better price.If its working with 2 outputs missing now . It will work even better with a full complement. Most likely solve the clipping LED issue as well.
Yes suitable outputs are available and not expensive.$5 a pop.
 
Hi, All,
Just found this thread... as I was looking for M4 info.
The story...
I have one, bought years ago, but have not used it beyond a few test and the occasional power-up (with a variac) to keep the electrolytics formed. Of course it's flawless... I liken it to a "short thick wire with gain"!
The pea lamps in the switches failed (daft idea), so I replaced them with LED's in separate near-flush mounts below the switches... looks fine. I need to clean the input pots as one has a slight scratchiness.
I'm now thinking of selling it to make space (too many tube amplifiers!), so I need to get a valuation. Note to moderators: I am not selling it here!
So, more work to be done...
Cheers,
Roger
 
Analogdino said:
Hi, All,
Just found this thread... as I was looking for M4 info.
The story...
I have one, bought years ago, but have not used it beyond a few test and the occasional power-up (with a variac) to keep the electrolytics formed. Of course it's flawless... I liken it to a "short thick wire with gain"!
The pea lamps in the switches failed (daft idea), so I replaced them with LED's in separate near-flush mounts below the switches... looks fine. I need to clean the input pots as one has a slight scratchiness.
I'm now thinking of selling it to make space (too many tube amplifiers!), so I need to get a valuation. Note to moderators: I am not selling it here!
So, more work to be done...
Cheers,
Roger
Click to expand...
Reguardless. You can not discuss monetary topics concerning your M-4 in this forum. Have Mods move your post to dollars and sense.
Nice amplifier though..
 
OK, noted. A while back I bought a C6 pre-amp to use with it... works fine, of course, but I now use the C6 on a pair of tube monoblocs as my main stereo system.
I'm tempted to use the tube amps in Winter and the M-4 in Summer...good idea, bobrown14!
Cheers,
Roger
 
I recall saying recently... (perhaps even here!), that the M-4 is like a "short thick wire with gain"... adds nothing, takes nothing away. Can't ask more than that.
Cheers,
Roger
 
DEAFASABAT said:
Curious what mods? Thanks
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I would refer you back to the threads on it but it seems they are gone. But just a few I can remember was total strip done and repainted chassis, total recap with bigger filter caps, new RCA's jacks, New speaker jacks. There was more done but my memory is not like it used to be.
 
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Forgive the ignorant newbie here but I ran across this thread while researching the M4 as a possible first separate purchase.
I do run two sets of (8 ohm) speakers but am unclear about the above statement from the M4 manual. Would running two pair of 4 ohm speakers in fact be a problem?

Thanks very much.
 

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I had an M4 for a while that I recently sold. Very nice sounding amp but not as resolving as my restored M60 or PC2602. Build quality is top notch and for a 100wpc amp it's got some heavy iron.
I was going to go through it to do a proper comparison but sold it to make way for a B2x.
 
Does anyone have recap the main capacitor for higher value?The original one seems is 15000ufx2,maybe can try higher value capacitor?
 
Just got my C6+M4 today. Would it be acceptable to run speaker output B to an amplified sub ? Assuming I can turn both A+B at the same time ?
 
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