McIntosh MEN220 Update

[jdandy]

Previously posted in the MC501 Thermal Shutdown (part 2) thread, my MEN220 was deemed to be defective after extensive trouble shooting by me, and aided by Ron-C. The MEN220 was causing overheating issues with my MC501 amplifiers. It was decided that the engineers at McIntosh needed to put the MEN220 on the test bench for some trouble shooting, so my MEN220 was returned to McIntosh in Binghamton, NY. The unit was examined for a number of hours by their engineering department, including operating it with the MC501 amplifiers. Using balanced interconnects between the MEN220 output and the amps, they were able to replicate the heat issue I discovered with my MC501 amplifiers. None the less, after a full computerized testing, and a complete engineering examination the MEN220 was determined to be operating properly with no defects.

In conversation with two different people at McIntosh, including one of the engineers who helped develop the MEN220, I was told that connecting the MEN220 outputs to a fully balanced power amplifier (MC402, MC501, MC1201, MC1.2Kw) should only be done using unbalanced interconnect cables. It was explained to me that the balanced outputs on the MEN220 are not true balanced outputs. In other words, the wiring of the three balanced output pins is not standard. Normally, pin #1 is ground/shield, pin #2 is (+) signal hot, and pin #3 is (-) signal cold. It was explained to me that the MEN220 balanced output pins are wired where pin #1 is ground/shield, pin #2 is (+) signal hot, and pin #3 is ground/shield. In other words, pin #1 and pin #3 are both connected to ground. There is no (-) signal cold on #3 pin, which is normally the inverted audio signal. Even though it is a balanced output connector, it is wired as an unbalanced connection that delivers only the (+) hot, and ground, the same signal found on the unbalanced output.

Knowing that the balanced connection is not really balanced explains why my fully balanced MC501 amplifiers were running hot on one half of the balance amplifier circuitry. The masquerading balanced outputs of the MEN220 are actually unbalanced, and consequently working half of the amplifier's balanced signal path with only half the audio signal necessary for proper balanced operation. This is causing the overheating issues. Now it makes sense why one side of a balanced amplifier's heat sinks become so much hotter than the other at output levels that are only 10% of an amplifier’s full rated output on peaks.

I have been instructed by McIntosh engineering to use the unbalanced outputs from the MEN220 to my MC501 inputs, and move the input mode switch on the amplifiers to the unbalanced position. This is true with the MC402, MC501, MC1201, and the MC1.2Kw amplifiers, also. According to what McIntosh engineering has said, using unbalanced interconnects from the MEN220 outputs will solve the amplifier heat issues. I was told this does not affect the MC252 since it is not a balanced amplifier.

Regarding the buzz and tick, tick, tick noise, thought to be clock noise, that I was experiencing with unbalanced interconnects between the MEN220 and the MC501's, I was instructed to power the MEN220 and the 501's from the same circuit. There was some discussion about the possibility that the Power Plant Premier powering the MEN220 from a different circuit than my amplifiers may have contributed to the noises. I will follow the instruction provided by McIntosh, and hopefully the MEN220 will integrate back into my sound system without the aforementioned noise issues. This will be determined once the MEN220 is back in the system. If the MEN220 operates my amplifiers properly using unbalanced interconnects, and I have no further amplifier overheating issues, particularly with respect to one half of each amp running at a much higher temperature than the other half, then I will keep the MEN220 in the system.

The sonic improvements delivered by the MEN220 in my sound system have been significant, enjoyable, and desirable. This is what I am after, and why I chose to add the MEN220 to my sound system in the first place. At this point, as long as the MEN220 is able to deliver on the improved audio performance without causing any negative issues with my amplifiers, I will accept the unbalanced interconnects as part of the package deal. Having said that, it is a bit disappointing not be able to continue operating my system fully balanced from source to speakers with the inclusion of the MEN220 in the system, although it can be installed in the Processor Loop or tape loop of a preamplifier without disturbing the balanced connections between the preamp and amplifiers.

UPDATE: I have received my MEN220 back from McIntosh. I installed it back into my sound system using unbalanced interconnects, and as instructed I powered it from the PS Audio Power Plant Premier that powers the MC501 amplifiers. No buzz, and no tick, tick, tick clock noises. Just as an experiment I tried plugging it into the Power Plant Premier on the other dedicated circuit that powers all my sources, and the buzz and tick, tick, tick noises were there. I tried plugging the MEN220 directly into the wall outlet that feeds the Power Plant Premier for sources, and the buzz and tick, tick, tick noises were there, also, so I plugged it back on the dedicated Power Plant Premier that feeds power to the MC501 amps. The noises disappeared.

I began playing music, and raised the preamp volume to a level that generated 500 watt peaks on the amplifiers, letting them play for a full hour. No ventilation fans were turned on, and the amps were installed inside the Salamander rack. No thermal shut down took place. The amps were measuring approximately 120 degrees on the heat sinks using my Fluke infrared thermometer, with both heat sinks on each amplifier measuring equal temperatures within 3 degrees. Both MC501 amplifiers were within 3 degrees of each other, measuring 118 and 121 degrees operating at full rated output on peaks. It appears that all is working well. I turned on the newly installed ventilation fans to see how much temperature reduction they would provide, and temperatures on both amps dropped 12 degrees to 106/109 degrees respectively while cranking out 500 watt peaks on both channels. This is the way I like to see things operating.

After considering connecting my MC501's unbalanced, I decided I would prefer to continue operating them balanced from the preamplifier, so I rerouted the unbalanced input and output connections on the MEN220, installing it into the C1000P Processor Loop, and activating the Processor Loop using the C1000P setup menu. I then changed the MEN220 menu settings to reflect the new connections, and reinstalled my balanced interconnects between the C1000P and the MC501's. The MEN220 is working perfectly in the Processor Loop, and sounding fantastic. The amps continue to operate cool on both heat sinks of each individual amplifier. This is much better, and my apprehension with the amplifier overheating issues has vanished.

It is unfortunate that the balanced connector and pin configuration drawing in the owner’s manual is incorrect. This causes misunderstanding for new owners attempting to use balanced interconnects between the MEN220 balanced outputs and the inputs on balanced amplifiers. Despite being disappointed about the MEN220 balanced pin configuration issue forcing me to use unbalanced interconnects, and the additional cost of having to purchase new Wireworld Silver Eclipse unbalanced interconnects to make the installation work, I still find Room Perfect to be so effective in improving my speakers sound in my room that I am willing to overlook what I now consider to be a McIntosh MEN220 design flaw. Other users may, or may not share my viewpoint. Although the MEN220 balanced outputs are actually wired in an unbalanced mode, once you are aware of the adverse condition presented to balanced amplifiers, and make the necessary interconnect changes, the MEN220 Room Correction System performs perfectly, and the sonic improvements with Room Perfect are nothing short of amazing. It really does deliver on its promise to reveal the full capabilities of your audio system, albeit with the interconnect caveat when connected to balanced amplifiers.

I want to thank the people at McIntosh who helped me with what I thought was a defective MEN220. Every person I contacted went out of their way to offer assistance. I appreciate those who afforded their time when I called, and helped me understand the reasons behind my amplifier overheating issues.

[Ron]

Do you know whether the MX150 has true balance outputs. I did not notice overheating when I owned the MEN220 hooked up with balanced interconnects.

[Masterlu]

Originally Posted by Ron

Do you know whether the MX150 has true balance outputs. I did not notice overheating when I owned the MEN220 hooked up with balanced interconnects.

The MX150 does have true balanced outputs.

[klipschfan]

In conversation with two different people at McIntosh, including one of the engineers who helped develop the MEN220, I was told that connecting the MEN220 output to a fully balanced power amplifier (MC402, MC501, MC1201, MC1.2Kw) should only be done using unbalanced interconnect cables. It was explained to me that the balanced outputs on the MEN220 are not true balanced outputs.

Thanks for the info Dan...

Not pleased with that at all...
I must have missed that paragraph in the manual. Would bet that quite a few of the McIntosh users have not only a fully balanced amp, but a fully balanced system.

[Still-One]

Dan
Thanks for the detailed update. I kind of figured it was the unbalanced to balanced issue that has been identified in other discussions on the net that causes the amp to do most of the work on one side. In fact this comes up in a review in this months Sterophile too.

I will probably leave mine connected as is or remove it if it ever causes an issue. I am not going to purchase 25ft unbalanced interconnects that cost as much as the MEN-200.

I don't understand the noise issue you were getting when the MEN and AMP's (with PPP's) were on different circuits. As you know each of my amps has its own circuit and the MEN is on a separate circuit with all of my sources, pre, and APC S-15. No ticks, clicks or pops. (except when playing vinyl of course)

How did you first hear it?
Jim

[Still-One]

Originally Posted by klipschfan

In conversation with two different people at McIntosh, including one of the engineers who helped develop the MEN220, I was told that connecting the MEN220 output to a fully balanced power amplifier (MC402, MC501, MC1201, MC1.2Kw) should only be done using unbalanced interconnect cables. It was explained to me that the balanced outputs on the MEN220 are not true balanced outputs.

Thanks for the info Dan...

Not pleased with that at all...
I must have missed that paragraph in the manual. Would bet that quite a few of the McIntosh users have not only a fully balanced amp, but a fully balanced system.

Are the outputs of the MCD-500 truly balanced? I know several individuals run that directly into their amps using the balanced outputs?

[Still-One]

Originally Posted by Ron

I did not notice overheating when I owned the MEN220 hooked up with balanced interconnects.

I have never had by amps shut down for any reason either and I would have never known about this issue without Dan's detailed posts. Just last week I did purchase a device to measure my amps at what I would call above normal (or safe) listening levels and found there was some side to side and amp top amp differences but never anywhere near the extent Dan saw. Then again my amps never hit 120 watts for levels in the mid to high 90dB range.
Jim

[jdandy]

Originally Posted by Still-One

I don't understand the noise issue you were getting when the MEN and AMP's (with PPP's) were on different circuits. As you know each of my amps has its own circuit and the MEN is on a separate circuit with all of my sources, pre, and APC S-15. No ticks, clicks or pops. (except when playing vinyl of course)

How did you first hear it?

Jim.......I first discovered the buzzing and tick, tick, tick noise during my first effort at trouble shooting when I changed the balanced interconnects to unbalanced between the MEN220 and the amplifiers. When I heard the noises it never dawned on me to try plugging the MEN220 into the other dedicated circuit. Ron-C suggested to me that I not plug the MEN220 into the Power Plant Premier, saying it might be an issue with the Class D amp in the PPP. The McIntosh engineer suggested using the circuit that the amps were powered from, and said he did not believe the PPP was the problem.

[jdandy]

Originally Posted by Still-One

Are the outputs of the MCD-500 truly balanced? I know several individuals run that directly into their amps using the balanced outputs?

Jim.......The MCD500 has a true balanced output, with pin #2 and pin #3 both having voltage, only inverted.

I measured the balanced outputs of the pins from the MEN220. The only pin with voltage is pin #2. There is no voltage to ground on pin #1 or Pin #3. Pin #1 and pin #3 have continuity between them, as well as continuity to ground.

[gtubes]

Awesome update Dan, this is need-to-know information for many folks, extremely valuable findings, thx again, Greg