[B]Hafler mods - Worth it?[/B]

[analog addict]

Does anyone have an opinion anout the Musical Concepts Capacitor mod for the DH-220? It upgrades the the big 10,000 mfd caps to 27,000 mfd for $90. The amp has one of the older MC circuit board upgrades, but the amp itself has a noticable 60 Hz hum when fired up, plus it does give off a small thump to the speakers when turned on. I just don't want to spend the $$$ on a mod if I need to address something else, but I also want to make sure I don't need do do this mod first to protect my speakers...
Thanks,
A.A.

 

[grateful]

Sounds like a bargain and it might cure the hum problem.

 

[needforspeed]

I'd say so for it, I had both of mine done by them, though I went for there
"package" mods on both. Both amps were okay in stock form, never
any humming or much heat. But after the front end upgrades and
switching them both to dual mono, it was a big jump in performance.
Also for the money (under $1600) for both, it was a bargin. The dh500
went from 255wpc to 312!! Talk about headroom. There electronics are
very good, and workmanship second to none.

 

[Luckyman]

Musical Concepts is very reputable. They have done a lot og mods to my Adcom gear.Very pleased!

 

[d3imlay]

As i recall there is a 100 mfd cap on the board power supply input that could also cause some hum. If you can use a voltmeter check the AC voltage on the 10,000's. There should be less that 1 volt when playing and probably less than 500mv when idling.

 

[grateful]

Yes good suggestion there are 4 of them and they should just be changed. Notorious failures. I think they are rated 100v

 

[analog addict]

Thanks for all the great suggestions! Now for the difficult question. Would anyone be willing to hazard a guess if these 4 100mfd caps were changed out with the Musical Concepts M-220C circuit board upgrade that was performed? Also, if I had to guess, this upgrade is probably about 20 years old, so should they be replaced irregardless??
Thanks again,
A.A.

 

[d3imlay]

It's an accepted practice that electrolytics have a 10 year life expectancy. Usually they last much longer than that. If the mod is 20 year old it's time for a replacement.