mc240

About 30 years ago I had a "Guy" who fixed my MC240, and he built a switch box for the amp (see below pics). Turn on righthand switch: both outlets received power. Once the 150W bulb became fully bright, turn on left switch: bulb turned off, all power to MC240. I took his word that this was good...

Just had my MC240 recapped by the guys at HiFi Haven (did a great job), and just received some NOS input tubes (all Telefunken little tubes) and RCA black plates for the output tubes. They aren’t even close to being broken in, and I can tell an immediate difference in the sound; much louder on...

Hello I am a new member and I’ve been very grateful to the many posts all of you have on here that have helped me over the years. I have a MC 240, two of them actually, both bridged mono. One of them has hum, but only when the selector switch is in mono. Becomes less in twin mode and still less...

I was looking at the Larry Hodson McIntoosh Compendium and noticed there are early, mid, and late MC240 models. The appearance of my MC240 is consistent with a late MC240 with the fuse on the left of the angled faceplate, the single octal output, and then the speaker connectors in the middle...

Hello to all: New McIntosh owner, and have been scouring the board for info, but didn’t come across this question: Is there a problem with plugging the power cord of the MC240 into the C26 pre-amp? The MC240 does not have a power switch, so by plugging the power into the pre-amp, they can...

Hi all, Last night I was switching between DACs which I had attached directly to my MC240. My finger touched the end of one of the RCA cables attached to the "twin amp" output section of the MC240. I felt a significant shock (no damage done) coming from the end. I'm guessing this isn't...

Did some measurements and that need explaining to me please. I had a matched set of JJ 6L6GC in my MC240 and they were showing ma readings per tube of approx 20ma on each tube on one side and approx 15ma per tube on the other....this was weird - also the fact that when switching sided those...

I am confused about what tubes should go into this position as I understand they get run a bit hard there. I have new production tubes and am not certain if they are safe there either. I also would like to know if those tubes should be matched and measure high GM to have maximum effectiveness...

Hello all! I am new to the forum and just started dipping my toes into high end home audio. I am putting together a vintage set up and I’m looking for suggestions on the appropriate speakers to pair with it. I recently bought an MC240 amp and stumbled on a Sansui AU-7900 integrated amp at...

Hi all, Am I crazy to think about replacing/augmenting my MX110 in my system? I have an older MX110 M series unit paired with an MC240. Both units have been restored by Audio Classics. The remainder of my system is comprised of: Klipsch Forte III speakers, Sonos connect, and a Rega Planar 6...

I have an MC240 and a C26....Was wondering if they would be a reasonable trade for an MA252 or MA352 value wise. I am driving a pair of Klipsch Cornwalls

I purchased a well-used MC240 for restoration. After receiving it I noticed the label on the M-207A power transformer was discolored; specifically, the area that's usually black was a very light gold or golden-brown. The labels on the 210 A & B had a black background as normal. I didn't think...

Hi, I have a new tube preamp that I want to plug into my MC240 tube amp. Now this amp is used to receive a typical 2.5 volt output from a McIntosh preamp. My new preamp outputs only 1 volt a the pre out RCA jacks. My question is, at which position should I place the twin inputs volume pots of...

I was advised that this mod was safe and have been using an adapter for it but the nagging feeling in me suspects that I will do eventual harm to my 240. I need some hard facts here if anybody has it as to why I should or shouldn't continue. Just playing it all safe!!! Thank you in advance.

Hello everyone. This my first post. I have a mc240 and once i turn it on i hear a slight hum from the power tranformer. Nothing from the speakers until i crank up the twin mode gain controls past 2pm, then i’ll hear some hum from them. Also the PT seems too warm to the touch after amp has been...

Hello, Recently I bought old MC240, all original condition and I've replaced the all electrolytic capacitors. And found some of the bumblebee capacitors are cracked so I've replaced all bumblebee capacitors as well for the next 50 years. Without tubes, I've checked the B+, it's 440V so cool. And...

Just picked up a C20 (was told it was a C22 but the guy was wrong) & Mc240. Physically they're both rough but working. I have read the manual and done some googling but can't seem to find a good answer to a question I have. What is the difference between Stereo mode & twin mode? Only thing I've...

I became obsessed with higher fidelity sound through Jazz - and I remember hearing for the first time the muted trumpet of Miles Davis on vinyl and being emotionally floored. It was on a really bad system, but that didn't matter - the music went beyond the sound quality and that was my gateway...

Hi all, I was planning on completely recapping my mc240 and noticed that all the capacitors appear to be the "black beauty" caps with no bumblebees. Is there any significance to this? Is this better/worse/no difference from the bumble bees? From reading various threads, I have seen it...

New member here and I need help on my McIntosh MC240. I’ve done a bit of research and am still not sure how to proceed, so I am seeking the collective wisdom of this group. Background: The MC240 was my Dad’s amp. The last time I can clearly remember it in service was in the mid ‘70’s. I...

Hello Fellow McIntosh fanatics! I am currently working on Restoring my first MC240. I have already gone through the PS Section and am currently measuring all of the Carbon Comp resistors and Capacitors. There is some debate o whether to leave the Red Lettered .22uf 600V Black Beauties in or not...

I imagine this would be because of a short down the line on the primary side, but could capacitor charge cause this? Installed all new power supply caps and checked against the schematic. Will post photos if wanted. Obviously the AC primary would measure a low DC resistance from the windings...

Hi! Just wondering if I can sub in an old RCA black plate that has differing GM readings (perhaps 20% difference) without it affecting the rest of the amp's performance. Also suggestions about tolerances for all the other tubes with respect to each other and their own individual sections would...