Adcom GFA 585, Yeah!

[Guido]

Just bought a good condition Adcom GFA 585.

I can't wait to check it out. It seems to be a limited edition of the GFA 565 in stereophonic version.

Who knows more about this?

[spkrman57]

And I liked it enough until I found tube nirvana. Good deep bass and nice overall presentation.

Should be a good buy!

Ron

[Guido]

It arrived nicely.

BUT..

After connecting it I heard a nice hum and a radio station coming in over some ground loop

Must be some defect inside the amp.

I payed via paypal so if the seller makes any problems I'll redraw my money.

Damned its such a nice amp. Why the heck these stupid sellers don't check their gear before selling

[Audiobeer]

I would think that might be in the preamp. To test it run a cd player with a variable outbut like a poratble cd player through it and see what happens.

[Guido]

No, it's definitely not in the preamp. I just changed amps.

What can this be?

[spkrman57]

Connect speakers only and no input to the 585 and see if you still get that hum and radio signal.

If the amp itself is doing that, it would indeed be a rarity.

Ron

[Guido]

You're right!

Its only with my preamp. Radio comes with the right channel.

But why the heck I do not have this problem with my other amp ???

[Audiobeer]

Some amps are more sensitive to grounding issues. That's just a guess but I am usualy wrong.

[pentictonklaus]

Hi Guido !
I was desperately holding back on this adcom isue. I tried this brand before.
Sorry to hear you are disapointed. But my listening preference is different
anyhow. ( I gave my Ti 5000 away for free 3 years ago in Germany , no offence ) Try to get some amcron or crown Dc 300 a with a Velleman Dc preventer kit. Get the 4435's und Schmeiss den Adcom Dreck endlich in den Muell. ( get the 4435's and finally chuck the adcom ). Keep up the good work on all the other issues.

Klaus 4350 and 4435

[Zilch]

You're sure it's not extraterrestrials talkin' to ya over it, right?

[Audiobeer]

It's not the voices but the tapping on the shoulder that gets me everytime!

[Titanium Dome]

Sorry to hear about this, but it's not that uncommon when switching amps and pre-amps. A formerly good sounding pre-amp becomes just plain crappy when combined with a different amp OR an amp that seemed fine suddenly becomes a nuisance when combined with a different pre-amp.

I've got seven different brands/models of amps around the house (with multiples of some of those seven), and it's just astounding how some work well with some preamps and others don't. Yet, they all work well with something. I just had to learn what works well together and what doesn't.

Since I'm not an EE, this was all trial and error.

[Guido]

So guys!

I'll send it back and will get full refund.

Leaving the ground (and radio) noise it sounded not nearly as good as my modified HK870. See my other thread for HK870 modification that changes the HK870 into a top of the line amp.

And NO! It's not extraterrestrials! And NO! It's not the drugs or beer. There was a good amount of hum and there was a radio station in the signal

[LE15-Thumper]

There are ground float resistors that open those amps. I have worked on many of them for minor repairs. The output stages on those amps are insane. I have yet to see any blown outputs on any of the GFA545, 555, 565, 585 as well as the mark two versions.

You may also want to try one of those ground adaptor plugs that allows you to plug in only the hot and neutral.

It arrived nicely.

BUT..

After connecting it I heard a nice hum and a radio station coming in over some ground loop

Must be some defect inside the amp.

I payed via paypal so if the seller makes any problems I'll redraw my money.

Damned its such a nice amp. Why the heck these stupid sellers don't check their gear before selling

[Ian Mackenzie]

Someone might have modified the unit without telling anyone.

It might even be oscillating...eek.