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Adcom 555 Mk 2 Questions

I'm a newbie here. I'm hoping someone is familiar with the Adcom amps & can provide some insight.

Long story short: My NAD 2600 blew up from static electricity. A friend who is not an audiophile has offered me an Adcom 555 Mk 2 really cheap for $150.

The rest of my system is: Teac Esoteric P-10 transport to PS Audio sl3 D/A by Illumanati cable. McCormick Line Drive Deluxe passive pre. NHT 2.5I speakers bi-wired. All analog wiring is Tara. Also have analog components & a Pioneer universal SACD player. Listening comments below are with the digital front end.

I just plugged the Adcom in (I'm told it hadn't been used much lately) & have 3 concerns. With all 3 concerns, my question is, "Is this normal behavior for an Adcom amp?

1. The heatsinks are quite hot from playing 4 songs at normal volume

2. There is some light hiss in both channels, even with the input muted. One channel has more hiss then the other

3. The amp is quite a bit brighter then the NAD. It may need to warm up for awhile (though again, the heat sinks are almost too hot to touch)

Thank you for your answers!
moomoo
larryken
537 posts
 
it's a very harsh sounding amp...
gmuffley
132 posts
 
Something is wrong. I have 2 555s I use for bass amps and they do not run hot.
stanwal's avatar
stanwal
3,147 posts
 
It is my understanding that Adcom had 3 different companies make the 555 at different times so there was considerable variation between samples. At least some of them were considered good at the time. I have never heard of them running hot. It sounds as if this sample has problems or possibily someone has set the bias very high. I would be leary of an amp running this hot that was not class a.
windriver
22 posts
 
Sounds like your bias might need some adjustment and your amp could benefit from a good servicing. The upside is that they are fairly simple amps to have serviced and once running in top shape will have great sound for the $ 150 that you paid.
moomoo OP
81 posts
 
Adcom emailed me back. They say the heat is likely a bias adjustment issue & the differing levels of hiss could be of concern.

The person I got it from has 2 more, so I may try another, but I'm also not real thrilled with the sound. I didn't think anything could make my NHT's sound bright; I'm used to them being a bit on the dark side! Being on a budget, one of his other amps may still be a short term solution, though.

Thanks for all the replies both on & off list, much appreciated!
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