Oh, I thought we were talking about the OP's amps. Sorry. I guess he still hasn't posted photos of the underside.
-
Feeling lucky? Check out the AK 24th Anniversary Giveaway thread and join in the fun!
McIntosh MC60s - advise on what’s been restored
- Thread starter nathan88
- Start date
Seamaster
Active Member
I am not trying to be a deep shxt to bash MC60, BUT the musicality and enjoyment of MC30 is beyond a technical level, they just sound right, the rightness clicked my brain.
I don't think anyone is arguing with you about that, per se. What we're trying to do is help the OP determine what kind of condition his amps are in. To that end some pictures of the underside would help, that's all.
after a lot of hesitation (due to fear), i said “screw it” and opened up the MC60s.
Here are the “innards” of the left amp. I will post pics of right amp separately.
The s/n isn’t on the chassis and wondered if it’s on the inside.
Anyone know what the markings mean?
And rectifier tube mismatch? It’s a biggy? (It’s in the pictures i posted two weeks ago and someone pointed it out too!). What’s the best resource/website for tubes?
And anyone know who might have restored (or serviced) this one?
Here are the “innards” of the left amp. I will post pics of right amp separately.
The s/n isn’t on the chassis and wondered if it’s on the inside.
Anyone know what the markings mean?
And rectifier tube mismatch? It’s a biggy? (It’s in the pictures i posted two weeks ago and someone pointed it out too!). What’s the best resource/website for tubes?
And anyone know who might have restored (or serviced) this one?
Attachments
One blue Sprague Atom electrolytic cap appears to have a manufacturing date of the 5th week of 2010. [1005H592...]
Again... ;-) These appear to have been completely and competently refurbished. I wouldn't have used boutique caps myself, but Auricaps are well-made. Between that and the Authenticap cans on the top side, I don't see that there's anything to do.
who ever did the work used some nice parts. Those caps were all the rage maybe 10-12 years ago. Some high end OEM manufacturers used them for a period of time.Thank you for pointing that out.
The “air” in the music is just different. Me likey
Likely still quite good. I would listen to them as they are. My guess is they sound pretty good. a
The only thing I might consider doing is adding a .33uf film cap as a bypass to the 100uf electrolytic in the feedback loop.
The markings inside the amp likely indicate which transformer tap was wired into the primary and likely a measurement value for the bias voltage for the 6550 tubes.
Bill Ferris
Lunatic Member
FWIW, I always rewire the power transformer`s optional 126 volt primary for better compatibility with the modern common higher line voltages of 120 +AC verses the factory`s default of 117 v AC being that the amp`s designed era the common line voltages hovered around 110 ~117 volts AC, though I see that a thermistor that has been installed in the power transformer`s primary input that might mitigate the desire/need to switch over to the factory`s optional 126 v tap.
On my 2 MC 30ties, & single 60, I did both PT primary modifications well over a decade back, as my nominal AC incoming line voltage is always a bit over 120 v.to keep the filament voltage very close to the tube`s manufacture`s specification.
I also see those 2 very important to be matched factory original 2 watt 12k carbon drift prone resistors haven`t been replaced with modern much more stable HQ 1% versions, which surprises me greatly, as every one of those era Mc. tube amps that has ever been brought to me for repair/rework/rebuild over the decades have always needed them to be replaced, being out of factory hand selected matched spec. for the amp to meet it`s factory`s .5% THD/IMD distortion specifications.
Oh well, just things I noticed from the pics.
Enjoy.
On my 2 MC 30ties, & single 60, I did both PT primary modifications well over a decade back, as my nominal AC incoming line voltage is always a bit over 120 v.to keep the filament voltage very close to the tube`s manufacture`s specification.
I also see those 2 very important to be matched factory original 2 watt 12k carbon drift prone resistors haven`t been replaced with modern much more stable HQ 1% versions, which surprises me greatly, as every one of those era Mc. tube amps that has ever been brought to me for repair/rework/rebuild over the decades have always needed them to be replaced, being out of factory hand selected matched spec. for the amp to meet it`s factory`s .5% THD/IMD distortion specifications.
Oh well, just things I noticed from the pics.
Enjoy.
what would “on” value and “off” value entail in terms sonic signature? any idea?
that is very precise, wow. i don’t even know what it means and will look it up
One blue Sprague Atom electrolytic cap appears to have a manufacturing date of the 5th week of 2010. [1005H592...]
you may not hear it exactly, but it will often measure as higher distortion than it should, or you may get hissing or static noises if the resistors are failing in a noisy way. Voltage measurements may also show things as being out of spec.what would “on” value and “off” value entail in terms sonic signature? any idea?
all that date code means is the cap appears to have been made in 2010. Whether it was installed in 2010 or sat in a box for years before being installed is unknown but the work can't be more than 16 years old.
quite a bit to unpack here (and with other replies, too). This is extremely new to me so I will have to look up the roles of “feedback loop” and what those different capacitors mean. For now, I have hooked up the MC60s to a WiiM Ultra Streamer and am really loving what they can do in my study room with Sonus faber Electa Amator III speakers. The (getting into audiophile terms now) placement of instruments in familiar tracks is “new”. Some instruments land in the middle of the room, for example, which I did not expect. Is it the recording itself? Or is the amp playing a role? I think it’s the latter, because this is new experience for me, listening to the same track.
Or it’s psychoacoustic behavior: my brain is playing tricks.
Regardless, it’s such a fun-filled experience and I can’t wait to research further on what these other various parts mean and what role they play in the sonic signature.