Gallien Krueger 800RB Discussion

[Ben Abraham]

I'm confused. Are you using one GK head that's configured differently for bass and guitar or are you using two GK heads? Any particular reason you're running in biamped?

Just the one GK. I wanted to use the "high" out for guitar so that I could set the crossover frequency somewhere amenable to guitar tonez.

Interesting. Well I think you should be fine Bi-Amping it and running it out of the high speaker out, so long as the impedance is matching, I've done that before and it was fine. I think you can run 8ohm output to a 4ohm cab and be fine. But NOT a 4ohm output into a 8ohm cab. I think that's how it works, someone correct me if I'm wrong.

I'd be curious to hear how that set up sounds on guitar.

For the low output, I think it's 4ohms if you're using both outputs. I run my bass rig bi-amped and I run through the low out into a 8ohm 1x15 and it's been fine/

[1009]

Interesting. Well I think you should be fine Bi-Amping it and running it out of the high speaker out, so long as the impedance is matching, I've done that before and it was fine. I think you can run 8ohm output to a 4ohm cab and be fine. But NOT a 4ohm output into a 8ohm cab. I think that's how it works, someone correct me if I'm wrong.

I'd be curious to hear how that set up sounds on guitar.

This is more or less what I was thinking.

At low volumes, it sounds great on guitar: very transparent to the TS-50's sound (the effects return is post-eq), and the crossover lets me brighten up the delta pro-thefuck I have in my 15. I can also add in some GK dirt with the boost, which might be a nice option.

[Ben Abraham]

Just edited my post to address your bass concerns.

[benadrian]

Interesting. Well I think you should be fine Bi-Amping it and running it out of the high speaker out, so long as the impedance is matching, I've done that before and it was fine. I think you can run 8ohm output to a 4ohm cab and be fine. But NOT a 4ohm output into a 8ohm cab. I think that's how it works, someone correct me if I'm wrong.

I think that's wrong. With solid state (SS) amps, the speaker impedance must be matching or higher than the amp's minimum impedance. On SS amps you will often see print by the speaker jacks that say "minimum load 4 ohms". That means you could use a 4 ohm cabinet, 8 ohm cabinet, 16 ohm cabinet, or anything else, as long as it's above 4 ohms.

As for the 100w high frequency amp on the 800RB NEVER go below 8 ohms. It has text that says minimum impedance 8 ohm, and they mean it. I've seen a number of blown up 100 watt sections on GK amps, and they are not easy to fix.

[Ben Abraham]

Well if Ben Adrian says I'm wrong, I probably am. So listen to him.

On my bass rig, I have two 8ohm cabinets; I connect the high output into a 2x10 and the low output to the 1x15 and that's biamped. So far, nothing has a exploded.

[1009]

Interesting. Well I think you should be fine Bi-Amping it and running it out of the high speaker out, so long as the impedance is matching, I've done that before and it was fine. I think you can run 8ohm output to a 4ohm cab and be fine. But NOT a 4ohm output into a 8ohm cab. I think that's how it works, someone correct me if I'm wrong.

I think that's wrong. With solid state (SS) amps, the speaker impedance must be matching or higher than the amp's minimum impedance. On SS amps you will often see print by the speaker jacks that say "minimum load 4 ohms". That means you could use a 4 ohm cabinet, 8 ohm cabinet, 16 ohm cabinet, or anything else, as long as it's above 4 ohms.

As for the 100w high frequency amp on the 800RB NEVER go below 8 ohms. It has text that says minimum impedance 8 ohm, and they mean it. I've seen a number of blown up 100 watt sections on GK amps, and they are not easy to fix.

Yeah, this is where I'm at. I like the bi-amped high (100w/8ohm) out when I'm playing guitar, and the full-amped low (300w/4ohm) when I'm playing bass. The deltra-pro is an 8ohm driver, so I think I'm ok in both scenarios.

[Eugenius]

Well if Ben Adrian says I'm wrong, I probably am. So listen to him.

On my bass rig, I have two 8ohm cabinets; I connect the high output into a 2x10 and the low output to the 1x15 and that's biamped. So far, nothing has a exploded.

Two 8ohm cabinets fits within the minimum parameters of the amp. If you were to use two 4ohm cabs you would have issues.

[Luzwei]

Well if Ben Adrian says I'm wrong, I probably am. So listen to him.

On my bass rig, I have two 8ohm cabinets; I connect the high output into a 2x10 and the low output to the 1x15 and that's biamped. So far, nothing has a exploded.

CAUTION : Under no circumstances should the 100W and
300W outputs be connected together or to the same speaker!

This I have found here:

http://www.gallien-krueger.com/manuals/800rb.pdf

Does that mean that you shouldn't connect two separate speakers to two different outputs?

[1009]

CAUTION : Under no circumstances should the 100W and
300W outputs be connected together or to the same speaker!

Definitely not!!! I'm only using one cab, and I'm switching the connection at the amp when I move from guitar to bass and vice-versa. Only one speaker cable!

[benadrian]

Well if Ben Adrian says I'm wrong, I probably am. So listen to him.

On my bass rig, I have two 8ohm cabinets; I connect the high output into a 2x10 and the low output to the 1x15 and that's biamped. So far, nothing has a exploded.

That is totally safe.
8 ohm cab on the 8 ohm out of the highs. CHECK!
8 ohm cab on the min 4 ohm out of the lows. CHECK!

Hooray!

[Luzwei]

Well if Ben Adrian says I'm wrong, I probably am. So listen to him.

On my bass rig, I have two 8ohm cabinets; I connect the high output into a 2x10 and the low output to the 1x15 and that's biamped. So far, nothing has a exploded.

That is totally safe.
8 ohm cab on the 8 ohm out of the highs. CHECK!
8 ohm cab on the min 4 ohm out of the lows. CHECK!

Hooray!

or like we do it now:

tow 8 ohm speakers to out of the 4ohm out. right?

[benadrian]

[quote="Luzwei"or like we do it now:

tow 8 ohm speakers to out of the 4ohm out. right?[/quote]

Yes.
Two 8 ohm speakers in parallel = 4 ohms. Totally safe.

[Luzwei]

or like we do it now:

tow 8 ohm speakers to out of the 4ohm out. right?

Yes.
Two 8 ohm speakers in parallel = 4 ohms. Totally safe.

We haven't really tried bi-amping. With our amp being so fragile I'm not so sure if we ever will.

[tontonp]

I've a question about the bi-amp knob and the High 100 watts channel.

Does any sound go out of the 100 w channel when the bi-amp knob is not engaged?
In this case, will the ouput of the 100 watts channel be "full range"?

[benadrian]

I've a question about the bi-amp knob and the High 100 watts channel.

Does any sound go out of the 100 w channel when the bi-amp knob is not engaged?
In this case, will the ouput of the 100 watts channel be "full range"?

Yes. If the bi-amp is not engaged then you have a full range 300w power amp and a full range 100w power amp.

[tontonp]

Thanx for the answer (Yeepie!).

[Ben Abraham]

So after owning my 800RB for the better part of a year, I only just found out how to get the thing to overdrive by cranking the input gain and boost. Don't I feel like a dumb.

[tallchris]

So after owning my 800RB for the better part of a year, I only just found out how to get the thing to overdrive by cranking the input gain and boost. Don't I feel like a dumb.

Oh yeah, the 400/800-RB actually has pretty damn good sounding solid state grit!

[benadrian]

So after owning my 800RB for the better part of a year, I only just found out how to get the thing to overdrive by cranking the input gain and boost. Don't I feel like a dumb.

Oh yeah, the 400/800-RB actually has pretty damn good sounding solid state grit!

That's from the FET that's just after the boost circuit. The op amps sound like shit when they distort, but it's very hard to get them to clip. The FET is designed to distort pleasantly. Whomever designed the original 400/800RB preamp back in the early 80s did a great job.

[japmn]

I've been seriously considering trying to trade my 75 Quad Reverb straight over for an 800RB and decent bass cab. I need a working, utilitarian, good sounding bass amp and do not need an over-sized cranky guitar amp.