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Thread: Adcom 555 II

  1. #1
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    Adcom 555 II

    Is any one using this 200 WPC amp?

    I just scored one on Flee-Bay a few days ago for cheap ($275 USD). I assume this amp is >20 years old. Typically, I don't mess with old electronics but I thought I would be adventurous.

    Do amps deteriorate with age or do they generally stay within the orignial factory specs?

  2. #2
    Senior Member pentictonklaus's Avatar
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    Since nobody else answered this, I give it a try.

    I listened once to this Adcom and it did not seem to be all that bad.

    To answer to your question, yes components do age. I did read a statement by Nelson Pass saying that you have to expect capacitors failing or going out of wack after some 20 years or so, totally depending on the hours that have been put onto the machine. That is also the reason why some folks modify the crossovers with new caps and claim a new found found heaven.
    Transistors fail as well, sometimes early or late. Every amp needs DC fault protection ( if not built in ) or will send drivers many times the value of the " E-Bay lucky find " " to speaker heaven.

    If you like the sound of the Adcom enjoy.
    Please check with the manufacture or any specs you can find what kind of protecton curciuits are standard with this model.

    If it is not a part of this amp, go and buy some external DC protection from Parts express as often dicussed in this forum. I learned this the hard way some years go when a Crown DC 300 a went DC and sent a couble of 2231 to recone hospital.

    Klaus

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    Thanks....

    I'll check the DC protection circuts on the "old" Adcom. I did note that the unit has 5 fuses at the back of the unit between the heat sinks. Is that a sign of DC protection or something else?

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    Senior Member Uncle Paul's Avatar
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    "Zobel is as zobel does"

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    Critical review - Adcom 555 II

    Ok, so I have had a chance to listen to this older unit for several days now using a pair of 4312 monitors.

    The unit has good power for its 200 WPC rating.

    I believe the mid range is relatively flat sounding. The bass and treble are a tad over bearing in my opinion, however.

    I have owned many higher power amps in my day (Denon, Marantz, Onkyo, etc.) but I find the newer Crown XLS amps are very nuetral and flat sounding from the bass through the treble range.

    All-in-all, I would recommend avoiding older amps in favor of the newer designs which I suppose are better in every way.

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    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by robertbartsch View Post
    All-in-all, I would recommend avoiding older amps in favor of the newer designs which I suppose are better in every way.
    And maybe your conclusions are subjective and influenced by what you're used to listening to?

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    I suppose most listening tests are subjective and judgemental. I have 4 systems in the house now and I have had the JBL 4312s monitors on three of them so I think the too big bass and too big treble on the Adcam is real.

    Anyway, I got the amp at a good price, so I will run it in the basement system for now.

  8. #8
    Senior Member LE15-Thumper's Avatar
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    My two cents

    I used to do warranty on Adcom products and I must say all in all they represented some of the "bang for the buck" products out there. A few models had some quirks, but their power amps were quite solid.

    The "triple nickel" as we called it was probably the best amp they made until the newer stuff came out in the new millenium.

    I remember bench testing (on my Sencore PA81) the "little brother" GFA-545II and getting close to 180watts per channel (both driven into 8 ohms) at onset of clipping. Not bad for amp under $700.00 rated at 100wpc.

    I should say that in more than 10 yrs of doing service on this brand, I only saw ONE failure (On the 555) that required changing of the ouput devices. Most failures were 10 and 100 ohm 1/4 watt fuse resistors that would open causing grounding issues on the front end thus causing DC offset putting the amp into protection mode.

    The output stages were insanely robust for what these units sold for. And as mentioned in this post, they had a very nice sound to them as well.
    LE15-Thumper
    "Give me JBL, or give me death"

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    what pre amp are you using? i have a pair that i run in mono. i either use a threshold , coda 02b (fet) or a old scott tube pre and get great results. they sound best with the coda. try it, you might find that they are not that bad. at 200 wpc for $275, they are a bargain.

    regards

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    I'm using the Adcom 5 channel preamp.

    Unfortunatly the amp seems to be malfunctioning now. The speakers have clicking noises when driven moderately hard.

    Does the Adcom 555 II have DC protection?

  11. #11
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    I don't believe the Adcom 555 II has DC circuit protection from what I have seen on the Net.

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    Super Moderator jblnut's Avatar
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    A friend of mine had this amp in his system back in the mid 80's. It was paired with some Snell speakers, an Adcom Preamp and a Sony ES CD Player. Your comments about flat midrange and boosted highs and lows match my memory of this perfectly. The highs would give a set of 901's a run for the money as "paint peelers". Whether this was a trait of the Snells or the Adcom (or both) it's hard for me to say now.

    I will say that I have really begun to realize that *everything* in a system can and will influence the sound. The speakers (and the room) are the biggest part of the equation obviously. But amps and even preamps can really change the sound dramatically if your speakers are transparent enough to reveal it.

    jblnut

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    Yeh, I suppose it will be a hard decision on whether to repair the Adcom power amp.

    I bought it for $225 but I don't really want to put more than $100 into an old unit like this.

  14. #14
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    Yeh, I suppose it will be a hard decision on whether to repair the Adcom power amp.

    I bought it for $225 but I don't really want to put more than $100 into an old unit like this.

  15. #15
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    I have an Adcom 555 II that my sister-in-law bought new along with preamp/tumer and CD changer. She has not used them in over 10 years since she moved. She asked me to sell them for her but when I hooked up the Amp, one channel is not working and the light is on. Is this a capacitor problem? Should I just sell it as is? It's in great cosmetic shape and used to work fine before she put it away.

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