2. amps-preamps
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Adcom GFA 555 amp upgrades

Hi. I own an Adcom GFA 555 amp, and I'm wondering if its practical to upgrade the amp to the standards of the Adcom GFA 555 series II (or better). Love the power and flexibility of this amp, as it powers my 4 ohm Kef Reference 103/4 towers with ease, but you know how it is, we audio junkies are always trying to squeeze a bit more fidelity out of our gear. Many thanks! -David
klipschking
johnss
569 posts
 
you'd probably be better selling the mark 1 and buying the 555 mk2s on the used market if you want an Adcom with a larger supply. But even then the 555 mk2 is not optimal.
keyd1
7 posts
 
Hi, just bought a used Adcom GFA 555. I believe it's the original model. Mark 1 is it?  Does this amp have an impedance switch on it, or does it just adjust impedance according to the speaker load? My first time going with 4 ohm speakers. Thanks.
213runnin
914 posts
 
No sir, there is no impedance switch.  That's for weaker amps or girlie receivers that have no jam.  It'll be fine with your 4 ohm speakers.


On the other hand, you might want to consider the age of the 555.  Shine a light inside the amp to see if there are any bulging or leaking caps, as a 30+ year old amp can develop issues.
timlub
2,039 posts
 
If you are truly a fan of what Nelson did with Adcom,  the 5802 is by far the best sounding Adcom amp.... Keeps that Adcom flavor, but more refined.  
tomfoolery
14 posts
 
I was an Adcom dealer long ago, I agree the 5802 was by far their best amp. It had that “French dark roast” character of the rest of the line but with a refinement not in the others. I think Audio Amateur had a regulator board that improved the 555 in much the same direction as the 5802, but never heard a “triple nickel” with it installed.
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