Powering off MC500 power amp

[Masterlu]

Originally Posted by miner

Main Output 1

[Formerly YB-2]

Originally Posted by r042wal

I have OEM incandescent replacements.

Great that you are keeping it 'new'.
There are 50,000 MTBF (~same as LEDs) lamps available for about the same few $$ as OEM. Also, believe Audio Classics sells new 'gels' for the meters should yours be faded.

[r042wal]

Thanks to all for the great help. You just made my life so much easier. If anyone has opened up one of these to replace the bulbs, I would be interested in some dialog. There is no DIY and since the amp is so heavy< I'm going to do it on my carpet.

I do not like the look of LED lights and already purchased the incandescence bulbs. I also have some new gels if I need them but they look a little small. I am in my mid 60s so whatever I solder in, I'm sure will outlive me.

[Formerly YB-2]

Whatever you do, don't pry on the glass with a screwdriver or anything metal (think broken or chipped).
Also, the black paint on the back of the glass is fairly soft and care needs to be taken to not mar it.
Heat from the bulbs can make things brittle (plastic parts, wire insulation), so move things slowly.
On the upside, if you botch the job McIntosh will eventually make you a new faceplate if they don't have one in stock.
And, don't over-tighten things when putting back together. That can also break the glass.

[Masterlu]

Rob… I have owned, and replaced bulbs in an MC500. It really is straight forward, and simple.

[Charles]

I have a question which someone might answer concerning the MC500. I read the specs and description of the amp. Extremely impressive, particularly the customer reviews. I always look carefully at Mac specs because unlike almost all other manufacturers, they are minimum specs. The damping factor is specified at 200. I at first thought this a miss print but on closer examination I believe it to be accurate. The MC500 is an autoformer power amp similar in design as far as I can tell, to all other autoformer Mac power amps. Does this mean that when Mac specifies the damping factor of their autoformer amps to be > 40, the true damping factor is actually 200 or is there something special about the MC500?

Best

Charles

[Formerly YB-2]

The MC500 is pretty much the last of the 'vintage' McIntosh amp designs (MC352 being the first of the 'new' design). The MC500 may have benefited from some of the new amp designs for its damping factor. You could ask McIntosh, but am guessing they will not offer any specifics on a design.

[Charles]

Originally Posted by Formerly YB-2

The MC500 is pretty much the last of the 'vintage' McIntosh amp designs (MC352 being the first of the 'new' design). The MC500 may have benefited from some of the new amp designs for its damping factor. You could ask McIntosh, but am guessing they will not offer any specifics on a design.

I did check and you are correct. The OM states a wideband damping factor of 200 at 8 ohms. The next large stereo amp was the MC2600 which states a damping factor of > 40. However I have now seen published specs for the MC500 stating a damping factor of of > 30. I think what all this means is that Mac amps have totally adequate damping factors. I don't want over damped bass. I have never felt that Mac amps have over damped bass. The person I discussed this issue with at Mac was very high on the MC500 and looking at the prices on the internet, it appears it is very sought after. It's a beautiful amp.

Best

Charles

[tdelahanty]

Dampening Factor is a ratio, speaker impedance to output impedance of the output stage (output Z should be as low as possible). In reality this relates to an amp's ability to control the fly-back pulse from the woofer, tight and defined bass. As an example Esoteric's S02 has a dampening factor of 1000. Did you ever consider why a Mac amp won't double its output at 4ohms? Yes it's due to the autoformer a dampening factor of 30 is very poor!!! Mac output stages can't supply enough current at 4 or 2 ohms.

[Formerly YB-2]

Originally Posted by tdelahanty

Did you ever consider why a Mac amp won't double its output at 4ohms? Yes it's due to the autoformer a dampening factor of 30 is very poor!!! Mac output stages can't supply enough current at 4 or 2 ohms.

You are correct that it is the autoformer, but nothing to do with the damping factor. Autoformers are used to provide the best impedance match for the amp with 8, 4 or 2ohm speakers (16ohm on older amps).
If, as you say, McIntosh amps cannot provide enough current at 4 or 2ohms I wonder why they are considered some of the best amps to use on the notoriously difficult to drive and current-hungry Magnepan speakers? My experience with McIntosh amps is that they do an excellent job of driving difficult (low impedance swings & large phase-angles) speakers. YMMV.