Adcom GFA 5500 - good buy?

[efrance45]

Hi all -

I’ve been looking for a power amp upgrade for my ELAC B6s for a stereo listening setup and have come across and Adcom GFA 5500 for $150. I don’t have pictures yet but the seller says it works well, just a couple front panel bulbs burned out. Is this a good deal? He’s selling other decently higher end vintage stuff too so I figured he’s probably taken okay care of his gear.

Oh and I’ll be using my marantz sr7200 as a pre amp for now

 

[Tedrick]

A Nelson Pass-designed 200 wpc powerhouse for $150?? Either it's intentionally priced low for a really quick sale, it doesn't work, or the owner doesn't know what they have. Run, don't walk, but be sure to audition before you lay down your money.

BTW, the '5500 only has a power LED and 2 LED's each for the distortion alert and thermal protection lights (total 5).

 

[efrance45]

A Nelson Pass-designed 200 wpc powerhouse for $150?? Either it's intentionally priced low for a really quick sale, it doesn't work, or the owner doesn't know what they have. Run, don't walk, but be sure to audition before you lay down your money.


BTW, the '5500 only has a power LED and 2 LED's each for the distortion alert and thermal protection lights (total 5).

it seems like it’s priced for a quick sale - if I’m not in the area and having a friend pick it up (who doesn’t know a ton about audio) what should I be sure he looks for? The seller said he could have it hooked up to hear.

And on another note, are the LEDs replaceable? He said “the bulbs on the front diodes need replaced”

 

[SaturationPt]

The power LED will be on, but the other 4 (1 each channel for thermal overload and distortion (input-output comparitor), these four should not come on unless there is distortion / thermal overload.

Very unlikely they're bad, most likely the owner has no idea how to operate the amplifier.

 

[efrance45]

Okay thanks so much! That’s kinda what I figured they were for. The seller just sent me some pics so I’ll throw them in here if I can.

 

[efrance45]

Alright so I finally got some pictures and the seller had the wrong amp listed. He actually has a GFA 5300 I guess the search continues!

 

[SoCal Sam]

Good buy but beware. No speaker relay is a serious threat if amp is not in top notch condition.

 

[efrance45]

Good buy but beware. No speaker relay is a serious threat if amp is not in top notch condition.

I’m sorry, I’m not well versed in the inner workings of amplifiers. What do you mean about the not having a speaker relay? And were you saying the 5300 is a good buy?

 

[RossW]

$150 is pretty much top dollar for a GFA-5300. From an inexperienced seller with no service history $100 is more reasonable.

Many amplifiers have a relay on the speaker outputs with a circuit that senses DC voltage on the outputs. In theory if something goes majorly wrong (a transistor shorts out, you lose a voltage rail in the power supply, etc.) it will prevent your speakers from getting smoked. There are plenty of high end amps that don't have such a relay, but as SoCal Sam pointed out, it does add some risk if the amp is not up to snuff.

 

[SaturationPt]

OTOH having a relay isn’t necessarily going to save speakers either if an amp malfunctions, I’m personally aware of two TOTL receivers with protection relays that malfunctioned and caught speakers on fire.

properly maintained equipment is the key here, not relays

 

[RossW]

Indeed, it is questionable that the little relays used by most manufacturers wouldn't just weld themselves shut if something catastrophic happened. They will provide good protection from DC offset adjustment issues (a silent killer...) or DC at the inputs.

 

[efrance45]

Thank you everyone for your knowledge. I didn’t know that’s how relays worked (or are supposed to)


I’ll probably keep searching for now!

 

[IMF_Pioneer]

One thing the relays are fantastic for is that when a amp powers down it will emit strange squealing noises and with a relay it instantly opens the circuit to the speakers and as such nothing is heard at all, but in the case of the GFA-5500 it does emit strange noises because it has no such relays and it very much annoys me everytime I turn it off with the obnoxious noises that I hear from the amp. There's nothing actually wrong with it and I've been told by a number of good techs that this is just the way it is and learn to live with it.

 

[slowpat]

My GFA-555 II will continue playing for a good 10-15 seconds after power off as the large caps discharge. The 5800 I have now goes out much quicker. Now the 5800 is a beast Nelson Pass designed as well.

Regarding what @SaturationPt said , it's so true about proper working amp. Once in a while , a properly working amp can still fail. I know a local guy that was running a couple of new Pass amps, when one went awry, and burnt up the woofer, midrange and charred the cabinet in the $4500 Silverline Sonatas...

 

[StimpyWan]

I have an Adcom GFA-5400, that I believe is an S2 version. It's got 2 extra PCBs compared to the S1. I wonder if it's some type of protection circuitry?

S1


S2

 

[StimpyWan]

Here's a 5300. It must be an S2 as well, since it has the 2 small extra PCBs in the left and right corners, just behind the face plate. The S2 versions have much nicer RCA input jacks on back. They sit flush to the back, and aren't recessed in, like the S1s. Easy to spot the 2 versions, by checking out the back.

 

[StimpyWan]

...The 5800 I have now goes out much quicker. Now the 5800 is a beast Nelson Pass designed as well....

That 5800 is definitely a Beast of an amp! I'd love to find one. Build a balanced system around it. I wonder how it sounds, compared to my 5400? Or your 555...?