Ampeg PF-500 problems

[Bright Midnight]

Have the PF500 for a month or two now, gets pushed hard 4 hours consecutive, 2 nights a week.... it seems to handle it pretty well, haven't even noticed the fan noise some speak of... great little amp, love it

 

[nutdog]

I have my first gig with it Friday. I'll see then how it does onstage. We are a three piece, and we play at reasonable volume. I lost two amps at this venue already...first my GK1001RB when a big cup of ice water fell into the cooling vent on top of the amp. I used my old Acoustic 370 which started distorting halfway through the night. I'm able to fix both of them (I'm a retired amp tech) but I've been jonesing for the Ampeg for a while. IF I get the cutting out many complain about, I'll return the head, but I suspect there have been enough revisions of this amp that the problem should be history. The problem with the Pro7 appears to have been a limiter problem, and a similar limiter is used in the PF500, if not the same circuit. I will take a backup head as I've learned to do.

GK has known about the ice water/cooling vent issue for quite some time and refuses to address it.

 

[Lync]

So far, one gig down and mine worked like a charm. Now you may say big deal, give it time. But it was a larger venue with a "sound system" that turned out to not have enough to have my bass plugged into it. I only had a single 15 cab thinking I was gonna DI in. So I had my master on 3pm and the gain around 1pm for the whole evening. I would say that is pushing the amp pretty hard. Not one issue.

 

[JimmyM]

GK has known about the ice water/cooling vent issue for quite some time and refuses to address it.

LOL!

 

[MJ_Sotti]

I haven't had any thermal problems since I A: started jacking the gain up to about 2oclock or B: started using my VT bass as the preamp. Being the dinosaur I am i considered "gain" a guitar amp thing, I think I was choking off the power amp. Now I give it enough to push.

BTW...the PF500 into a 8 ohm 410HE classic is bad to the bone.

 

[Steve Dallman]

I had my share of problems with the GK. When it was still under warranty, the tweeter amp stopped working. I sent it to GK. 6 weeks later I got it back. They said they couldn't find anything wrong, but they did upgrade the turn on pop circuit to current specs. I got permission to troubleshoot the tweeter amp without voiding the warranty, as I was a working amp tech. I found the problem to be the couple cap going into the tweeter amp. I replaced it and all was fine. GK tests the tweeter amp at 10k...it worked at that frequency but not at the crossover, 5k. GK now tests the tweeter amp at 5k.

But the work they did on the turn on circuitry...oy vey! They burned the circuit board when they put in an IC socket. There was solder dripping from the power amp board, that hung so low it almost touched the chassis. I sent them pictures. They apologized and said they held a seminar for in house techs on proper soldering and rework techniques. But until the ice water down the fan, the amp held up fine for 8 years of use. It even took a big beating when we totaled my truck last year. The head was thrown about 30 feet, bouncing on the ground. The DI knob broke off, and the tuner switch didn't work but all else was fine, once I cleaned all the dirt from it.

 

[Phlips]

What happens when you hook up an 8ohm cab to the speakon output, and an 8ohm cab to the 1/4 output, and then daisy chain another 8ohm cab of of the 1/4 one. 3.6ohms, right? Ampeg PF-500, 4ohm minimum.

 

[coreyfyfe]

What happens when you hook up an 8ohm cab to the speakon output, and an 8ohm cab to the 1/4 output, and then daisy chain another 8ohm cab of of the 1/4 one. 3.6ohms, right? Ampeg PF-500, 4ohm minimum.

2.6 ohms but below the 4 ohm minimum either way yes.

 

[blubass]

I'm glad this got brought back to the top...

Remember kids, this warning is pretty standard practice for many electronic devices, and I found it in the GK manual to keep it relevant...

WARNING:

TO REDUCE THE RISK OF FIRE OR ELECTRIC SHOCK,

DO NOT EXPOSE THIS APPLIANCE TO RAIN OR MOISTURE

Maybe the OP wanted to come out of retirement as an amp tech, but the best practice is to prevent issues like this by not using your amp or any nearby shelving as your drink holder in the first place. I mean my god, my feet are always firmly planted on flat solid ground when i play, and i'd rather have wet shoes than a wet amp! Maybe the amp was hot though and the ice was just good measure for cooling properties though... i'll refrain from judgement

 

[Phlips]

2.6 ohms but below the 4 ohm minimum either way yes.

Thanks Corey

 

[Downunderwonder]

What happens when you hook up an 8ohm cab to the speakon output, and an 8ohm cab to the 1/4 output, and then daisy chain another 8ohm cab of of the 1/4 one. 3.6ohms, right? Ampeg PF-500, 4ohm minimum.

Don't do that. 2.6 ohms will kill it.