Because old caps?

[lanchile]

Today I invited my friend that has a big amp collection and in his collection he has a McIntosh MC2105 Power Amplifier that looks like it came out of factory,it is a very heavy monster.Well we were intrigue if my nxv200 amp from Aussie Amplifiers can compete with a McIntosh.Well to make this short, We started with the test with some CD's that he brought (smooth jazz). His amp is just about the same power 100 watts per channel.The sound of this McIntosh MC2105 was very mellow and the bass was tight, the highs were a little too sharp and a little fatiguing.We listened to the amps for about 4 hrs.at the end We both were surprise with the results.We both agreed that the nxv200 amps from Aussie Amplifiers sounded much better and when I say better it means the sound on the nxv200 amp was not fatiguing at all, The bass and mid range sounded the same on both amps beatifuly!!!.
My friend was amaised of the quality of the sound of these diy nxv200 amps.
Now He is very anxious to build one of these diy amps. Do you think the "fatiguing" sound on the McIntosh MC2105 compared to the diy nxv200 amp is because of these "old" caps and old parts?.

[gmphadte]

Recap it with Nichicon muse audio caps and check for yourself. However, this will change the behavior of the McIntosh towards better side, hopefully.

Gajanan Phadte

[lanchile]

Originally Posted by gmphadte

Recap it with Nichicon muse audio caps and check for yourself. However, this will change the behavior of the McIntosh towards better side, hopefully.

Gajanan Phadte

My friend said He will recap "all" the amp with the best caps that He can get. He will start doing it next week. after that we will give it a try again. But I said to him to let it play it for a week or so before the try.

[djoffe]

The caps might be a problem, but I'd first recommend checking the bias current. That's typically the thing that changes the most, and can have a very significant effect on sound and listening fatigue. The measurable bit of evidence comes from x-over distortion, particularly at low signal levels. If that is blameless, then checking other things, like caps, makes sense.

[lanchile]

OK, today my friend and his friend were here with his "monster" rebuild. He did not work on it...He Brought it to an authorised McIntosh service center. He said The technician replaced all electrolytic caps, Checked bias, dc offset etc. He got it to original or better specification. The cost was $380.
We could hear the difference now, it sounds much much better. The test went 50/50 next to the NXV200, now the sound is not fatiguing as it was before.
I guess that was a $380 well spent!. The technician said to him ,his amp was in pristine condition inside and now it is like he turned back time to the first day this amp went out of factory!. Now my friend is very happy and I am too because, I know my amp sound quality is next to some of the big ones.
I guess now He has an excellent amp for at least 20 years more.

[Flatlander]

Out of curiosity, was the old McIntosh ever stored for an extended time or has it seen constant use during its life?

The reason I ask is that I have two original McIntosh MC2500 amplifiers. One of them has been in constant use since the early '80s while the other one rested for a decade. They both saw very heavy and constant pro-audio use when they were new-ish, them being a part of four racks of them that I used in my touring sound company. The one that lived inside the house in my main system still sounds fine.

The one that has had a long retirement is definitely "not quite right." Fatiguing would be one way of describing what I hear in the one that sat around unused for too long. I have wondered if just powering it up and giving it a good long romp, such as the full power complex impedance loads it used to suffer, might blow the cobwebs out of it or something (giving the caps a good deep, demanding charge).

It is good to know that having one of these amps serviced by the manufacturer is fairly affordable.