GK 800RB getting very hot. Is this normal?

[snowblinder]

I recently started using a GK 800RB head through an Ampeg 8x10 as my live rig. I typically have the boost knob cranked, the master volume at about noon, and the input volume at about 10:00. The EQ on the amp is set completely flat, and I use a Tech 21 VT Bass pedal in front to get an SVT-esque sound. Anyway...my band played a show recently, where I used this exact setup. Our set was approximately 45 minutes. The soundman ran a DI from the XLR jack on the rear of the amp. After we finished, I went to unplug everything and pack it up, and the top of the amp was extremely hot. Like, almost too hot to touch for more than a few seconds. This worries me because I just bought this amp, solely on the basis that it would be a more roadworthy, reliable alternative to hauling a vintage SVT (which has proven to be somewhat unreliable) around.

Should my 800RB be getting this hot after less than an hour of use?

[lbwdog]

Originally Posted by snowblinder

I recently started using a GK 800RB head through an Ampeg 8x10 as my live rig. I typically have the boost knob cranked, the master volume at about noon, and the input volume at about 10:00. The EQ on the amp is set completely flat, and I use a Tech 21 VT Bass pedal in front to get an SVT-esque sound. Anyway...my band played a show recently, where I used this exact setup. Our set was approximately 45 minutes. The soundman ran a DI from the XLR jack on the rear of the amp. After we finished, I went to unplug everything and pack it up, and the top of the amp was extremely hot. Like, almost too hot to touch for more than a few seconds. This worries me because I just bought this amp, solely on the basis that it would be a more roadworthy, reliable alternative to hauling a vintage SVT (which has proven to be somewhat unreliable) around.

Should my 800RB be getting this hot after less than an hour of use?

Shouldn't get too hot to touch. Obviously there are no fans, and the amp is cooled by the heat sinks. They can get pretty hot. Maybe try calling Gallien support. (or Bob G. may check in here in a bit.)

[woody357]

I have a older 800Rb, it gets hot but not that hot. I'd do as Ibwdog suggested, and call GK about it. You could also put a small fan behind your head to help keep it cool, because those heat sinks do get hot.

[WingKL]

Try some other cabs and see if it still happens. Besided the output transistor bias drifting, I think it can also get hot if there is something wrong with the cab.

[shoot-r]

Originally Posted by snowblinder

I recently started using a GK 800RB head through an Ampeg 8x10 as my live rig. I typically have the boost knob cranked, the master volume at about noon, and the input volume at about 10:00. The EQ on the amp is set completely flat, and I use a Tech 21 VT Bass pedal in front to get an SVT-esque sound. Anyway...my band played a show recently, where I used this exact setup. Our set was approximately 45 minutes. The soundman ran a DI from the XLR jack on the rear of the amp. After we finished, I went to unplug everything and pack it up, and the top of the amp was extremely hot. Like, almost too hot to touch for more than a few seconds. This worries me because I just bought this amp, solely on the basis that it would be a more roadworthy, reliable alternative to hauling a vintage SVT (which has proven to be somewhat unreliable) around.

Should my 800RB be getting this hot after less than an hour of use?

I ran that exact same rig for 22 or so years without any problems at all.
The two things IMHO that always have to be done with the G.K. 800 is, #1...use the 300 watt power amp into a 4 ohm load, and #2...have a small fan blowing on the back cooling fins.
Any small fan will do, a electronics fan from Radio Shack, (what I've always had), or a small clip mounted fan from Walmart, ect.
Bought my G.K. 800 new in 1984 and it's still going strong...with my fan "always" blowin' on the cooling fins.


Something I'd also check, make sure all eight speakers are working.
If one has failed that will throw the cabinets 4 ohm impedance out of whack and cause the head to run overly hot.

[Grooveman1961]

I use the 800 into an 8x10, and it gets very, very hot. The fan suggestion is a good one.

[snowblinder]

All eight speakers definitely work, I've checked that. I use the 300 watt amp, not the 100 watt one (did plenty of reading on that topic in this forum when I first purchased the amp). I had wondered if the fan would be a good idea, or if a fan was only helpful for keeping a tube amp cool.

Thanks for the replies. I'll be purchasing a small fan of some sort soon.

[YogaBear]

I love hot,

like tube amps





get a cooler haha

[shoot-r]

Originally Posted by snowblinder

All eight speakers definitely work, I've checked that. I use the 300 watt amp, not the 100 watt one (did plenty of reading on that topic in this forum when I first purchased the amp). I had wondered if the fan would be a good idea, or if a fan was only helpful for keeping a tube amp cool.

Thanks for the replies. I'll be purchasing a small fan of some sort soon.

I've had a fan on mine from day one and what I credit my 800's longevity too.
IMHO, not having a factory installed fan was the G.K. 800's only flaw.
Back when the G.K. 800's where a new design only some tube amps had a fan.
With todays designs, I can't think of a pro level amp, tube or S.S., that doesn't have fan cooling.

[snowblinder]

I'm going to be installing my 800RB in a four-space rackmount case in the next few days, as soon as my 800RB rack kit arrives in the mail. The case is a good five to six inches deeper than the amp itself, leaving plenty of extra room in the back for a permanently installed fan of some sort. Just have to find one now...

Also...would it be a bad idea to mount any type of one-space rack unit, such as a tuner or power conditioner, above the 800RB in a four-space case?

[shoot-r]

Originally Posted by snowblinder

I'm going to be installing my 800RB in a four-space rackmount case in the next few days, as soon as my 800RB rack kit arrives in the mail. The case is a good five to six inches deeper than the amp itself, leaving plenty of extra room in the back for a permanently installed fan of some sort. Just have to find one now...

Also...would it be a bad idea to mount any type of one-space rack unit, such as a tuner or power conditioner, above the 800RB in a four-space case?

My 800 also rode in a 4 space SKB case.
I had a singlespace tuner above it for years with no ill effects.
The fan was a 4" Archer from Radio Shack, mounted on a board, mounted on the back of the case blowing in.
It set back a few inches from the G.K.'s cooling fins so I could yearly brush out any bar gunk/crud that may have accumulated in the fins.
Another local bassist who also has a rack mounted 800 simply uses a clip mounted fan that he clips to the back of the rack blowing in that he got at a Walmart for a few dollars.
I've since taken my 800 out of it's rack, but I still use the fan on it.

[Standalone]

open a cold beer and set it in front of your stack. your amp will drink it on the astral plane and feel refreshed. only amps with soul, such as the 800RB, can do this.

[snowblinder]

Update: I found one of these at Wal-Mart for $5



Mounted it in the back of my rack, blowing directly onto the GK's heat sinks. Problem solved. The amp didn't break a sweat last night after a long, loud set in a pretty warm venue.

[will33]

Originally Posted by snowblinder

Update: I found one of these at Wal-Mart for $5



Mounted it in the back of my rack, blowing directly onto the GK's heat sinks. Problem solved. The amp didn't break a sweat last night after a long, loud set in a pretty warm venue.

A little fan like that was my solution to SWR's without fans, just heatsinks getting too hot. It is unusual however for an 800rb to run that hot. I've played 4 hour gigs with them in 100+ degree summers and they handle it fine.

It may be an indication of a future problem but first make sure everything is hooked up right and nothing is playing at too low an ohm load. Also a heatsink needs space too above and below it so heat can rise off of it and cooler air can replace it. The little fan makes that null and void though.

[shoot-r]

Originally Posted by snowblinder

Update: I found one of these at Wal-Mart for $5



Mounted it in the back of my rack, blowing directly onto the GK's heat sinks. Problem solved. The amp didn't break a sweat last night after a long, loud set in a pretty warm venue.

+1!!!

[KillerQuebec]

I need one of those too. BRB.

[KillerQuebec]

$9 @ walmart today. I got the last orange one!