GK Bi Amp Feature

[dragoon419]

Hey.

Could someone tell me exactly how the bi amp feature on the GK 700RB. Does it allow you to control the tweeter on the amp you are using, or do you need another amp all together?

If I were to hook up a 4 ohm cab, would I be able to control the tweeter on it using the bi amp feature?

 

[JKT]

Hey.

Could someone tell me exactly how the bi amp feature on the GK 700RB. Does it allow you to control the tweeter on the amp you are using, or do you need another amp all together?

If I were to hook up a 4 ohm cab, would I be able to control the tweeter on it using the bi amp feature?

The tweeter control on your Gk controls the built- in
tweeter amplifier. To control the tweeter in a cab it must be hooked to the 700RB via the 4 wire speakon connector. Note-4 wire not 2.

JKT

 

[JanusZarate]

The "bi-amp" on modern GK amps (EXCEPT the 800RB) works like this:

There are two poweramps inside - one for your main drivers, and one for your tweeter. The amp has a preset crossover (5KHz and above goes to the tweeter, IIRC). You can control tweeter volume and a few characteristics of the crossover from the front of the amp.

The major advantage of this setup is that if you're cranking your GK amp's Boost knob for some growl and/or mild overdrive, the tweeter is unaffected; it stays clean because it's on a separate poweramp system. The Boost and growl come from the circuitry on the path to the main poweramp. (Note that if you use an overdrive pedal, then it doesn't matter - your tweeter's going to be hit with overdrive. )

The bi-amping on GK amps only works with two kinds of cabinets:
- GK cabinets with tweeters
- Other cabinets that have been re-wired to accomodate the GK bi-amping system

Otherwise, you can still run any cabinet on the GK amp; you'd just be running it in full range mode, and your cab would handle the tweeter attenuation and crossover. The tweeter amp would be disconnected.

You need a 4-pin Speakon cable to use the bi-amp feature; these come standard with new GK cabinets. If you use a typical 2-pin speakon (+1/-1), your cabinet will run in full range mode. GK cabs can work either way, but you'll probably prefer to make the most of the bi-amping feature.

 

[greenboy]

Some day I should dl a GK manual to see if the relevant info about the bi-amp arrangement and the Speakon wiring isn't already in there. This topic sure seems to come up a lot.

 

[dave64o]

The "bi-amp" on modern GK amps (EXCEPT the 800RB) works like this:

There are two poweramps inside - one for your main drivers, and one for your tweeter. The amp has a preset crossover (5KHz and above goes to the tweeter, IIRC). You can control tweeter volume and a few characteristics of the crossover from the front of the amp.

The major advantage of this setup is that if you're cranking your GK amp's Boost knob for some growl and/or mild overdrive, the tweeter is unaffected; it stays clean because it's on a separate poweramp system. The Boost and growl come from the circuitry on the path to the main poweramp. (Note that if you use an overdrive pedal, then it doesn't matter - your tweeter's going to be hit with overdrive. )

The bi-amping on GK amps only works with two kinds of cabinets:
- GK cabinets with tweeters
- Other cabinets that have been re-wired to accomodate the GK bi-amping system

Otherwise, you can still run any cabinet on the GK amp; you'd just be running it in full range mode, and your cab would handle the tweeter attenuation and crossover. The tweeter amp would be disconnected.

You need a 4-pin Speakon cable to use the bi-amp feature; these come standard with new GK cabinets. If you use a typical 2-pin speakon (+1/-1), your cabinet will run in full range mode. GK cabs can work either way, but you'll probably prefer to make the most of the bi-amping feature.

Nice description.


I had my Dr. Bass cabients built so I could run them bi-amped or full range but I found that bi-amping didn't make much of a difference, at least in my set up. Maybe I would have gotten different/better results using GK cabinets that are designed to work in this configuration?

Personally I would have preferred the crossover in the GK heads be lower, maybe as much as an octave (2500 Hz), but I'm sure there are plenty who'd disagree.

 

[JanusZarate]

Some day I should dl a GK manual to see if the relevant info about the bi-amp arrangement and the Speakon wiring isn't already in there. This topic sure seems to come up a lot.

It's in every GK amp manual, actually. But most musicians read the manuals to their gear, so I'm really just regurgitating what everyone knows already.

On a more serious note... I really don't know why everyone dodges reading the manual. Practically all the answers are in there, save for a few confusing issues (like their explanation of the dual poweramp system in the 2001RB).

I had my Dr. Bass cabients built so I could run them bi-amped or full range but I found that bi-amping didn't make much of a difference, at least in my set up. Maybe I would have gotten different/better results using GK cabinets that are designed to work in this configuration?

It generally doesn't until you push it hard, or are trying to get a lot of extra growl and overdrive from the main power section. Other than that, the difference it makes really isn't that dramatic or significant; it's certainly not a night-and-day thing.

 

[greenboy]

If I have an issue or spec that needs claification I generally RTM first - because the manual doesn't give seven conflicting and poorly worded bits of advice, some of which are generally dangerous to equipment or personage ; }

 

[Geddyfleaharris]

On a more serious note... I really don't know why everyone dodges reading the manual. Practically all the answers are in there,

+1. Pretty much everything I buy I read the manual at least once. I refer to my GK manuals on a pretty regular basis just to refresh the old brain on certain things.

 

[ishouldbeking]

For the first few years of owning my 2001RB, I actually kept the manual in the rack case with the head... I can't count how many times I had to bust that thing out at practice.

GK gear can be slightly confusing at first -- especially the 2001rb -- but once you have a good understanding of all the functions it makes sense in it's own hyper-complicated way. Mostly.

 

[AlembicPlayer]

the bi-amp feature is useless to me.
I don't use tweeters.

however, if it had two separate power sections that had serious power for each section AND a variable x-over then I could use it.

full range, daisy chain two cabs and my new 1001RB II is a very nice rig.
but for a real bi-amp rig, I'll use my rack rig with a stereo power amp.

 

[Band Dad]

I put together a rig for my son using a GK 800RB. Mystic Boo suggests that this is a different beast altogether. I wasn't aware of that, but then I'm not familiar with GK's newer heads.
I'm running an Avatar 500W 212 to the 300W, 4 ohm, "LO" output and an ADA 200W 115 to the 100W, 8 ohm, "HI" output and full. It's been recommended that one run this head "Full Range" as most cab setups are not really all that HI FI to take advantage of the bi-amp feature. My ADA uses an EV 15L which is primarily a guitar driver, though recommended by EV as a bass or sound reinforcement driver.
I think I have what might be the best example of how best to take advantage of GK's bi-amp design. Largely though, people here on TB seem to discount it as not being terribly worthwhile.
Good thread. I dig GK.

 

[fretster]

The "bi-amp" on modern GK amps (EXCEPT the 800RB) works like this:

So, to finish the GK story, the 800RB works like this:

It does not use the 4-wire Speakons. Instead, it has separate 1/4" speaker outputs on the back. Two for regular, two for tweeter. Labeled Low and High. There is a button on the front that says Bi-amp Mode, and a crossover knob where you dial in the frequency of the crossover circuit. And then there are separate gain controls for the low and high amps. If bi-amp mode is diasabled, then the two amps are blended and the outputs all get the same signal. If bi-amp mode is turned on, then the High amp drives the high speakers, and low amp drives the low speakers, and you get to spend hours dialing in different levels for amp gain and crossover.

Overdrive the low, to get crunch, but keep the high clean because the high sounds bad if distorted. My rig came with a 115 and a 210, and had the 115 plugged into "low" and the 210 into "high". I kept the crossover fairly low, so that the 210 would have something to do. Sounded great.

Then I discovered the AccuGroove Whappo Jr and the Mesa Walkabout, and gave away the GK rig. (Well, permanent loan is more like it.)

 

[AlembicPlayer]

So, to finish the GK story, the 800RB works like this:

It does not use the 4-wire Speakons. Instead, it has separate 1/4" speaker outputs on the back. Two for regular, two for tweeter. Labeled Low and High. There is a button on the front that says Bi-amp Mode, and a crossover knob where you dial in the frequency of the crossover circuit. And then there are separate gain controls for the low and high amps. If bi-amp mode is diasabled, then the two amps are blended and the outputs all get the same signal. If bi-amp mode is turned on, then the High amp drives the high speakers, and low amp drives the low speakers, and you get to spend hours dialing in different levels for amp gain and crossover.

Overdrive the low, to get crunch, but keep the high clean because the high sounds bad if distorted. My rig came with a 115 and a 210, and had the 115 plugged into "low" and the 210 into "high". I kept the crossover fairly low, so that the 210 would have something to do. Sounded great.

Then I discovered the AccuGroove Whappo Jr and the Mesa Walkabout, and gave away the GK rig. (Well, permanent loan is more like it.)

nice post, thanks!
looks like I should have got the 800RB!
do you know what the watt output is for each section?

mmmmmm whappo jr

 

[Band Dad]

Thanks fretster. It's beginning to sink in!

AlembicPlayer, my 800RB has 300W to the "LO" (4 ohm) and 100W to the "HI" (8 ohm) outputs. The newer models have, I think, a 50W "HI", making it better used for a tweeter than a separate cab, I would think.

 

[AlembicPlayer]

Thanks fretster. It's beginning to sink in!

AlembicPlayer, my 800RB has 300W to the "LO" (4 ohm) and 100W to the "HI" (8 ohm) outputs. The newer models have, I think, a 50W "HI", making it better used for a tweeter than a separate cab, I would think.

oh, I see
thanks for that info
still not enough to use a separate cab as you said.

I just used my 1001RB for the first time on a gig last weekend and was very impressed with it. I'm very happy with the purchase so far.

 

[Flintlock]

oh, I see
thanks for that info
still not enough to use a separate cab as you said.

Guitar cabinet? If its just handling the highs then it should work (and sound) fine right?

 

[Band Dad]

My ADA 115 Bassline cab is a bass cab that originally had a 300W EV driver installed; that was blown when I got it, and I replaced it with a200W EV 15L from another bass cab. This speaker is meant for a number of applications, with guitar being what it was designed to handle as well as bass and sound reinforcement (PA). 100W is plenty to push this in the range it was designed for. That range just happens to be a more treble, hi-fi, or modern tone. Great mids and treble. Not bad on the low-end, either, but then the Avatar 212 handles that job exceedingly well. The EV doesn't need a lot of power to handle the upper register. It gets plenty loud, is crisp and bright, and it isn't being asked to handle the low-end. Perfect for GK's 800RB in full range, and while I haven't done much experimenting with the bi-amp feature (the rig has only just been put together and not a lot of time to check it out), it should handle that as well as GK intended as its use.

Edit: Here's a thread that shows the setup. http://www.talkbass.com/forum/showthread.php?t=296133&page=11

 

[JanusZarate]

AlembicPlayer, my 800RB has 300W to the "LO" (4 ohm) and 100W to the "HI" (8 ohm) outputs. The newer models have, I think, a 50W "HI", making it better used for a tweeter than a separate cab, I would think.

Yep. The major difference, besides power, is in the crossover point. On modern GK heads, it's set at 5KHz - well within treble territory. Up there, a tweeter is the best tool for the job. On the 800RB, the crossover point is not only lower, but it's flexible - you can set it pretty low and give the cabs in the 100W "HI" section a good amount of middle and upper midrange.

I don't remember the range of the Crossover knob, though. It's not in the manual...

One other thing to note - the modern bi-amping only works for tweeters on GK cabs, or on cabs rewired to use it. You can't run the horn amp signal to a regular driver. On the 800RB, you can use any cab you want as long as it's 8 Ohms or more.

It's partly why GK prefers to call their modern bi-amping the "Horn Management System" (HMS).

 

[megadan]

I'm thinking about picking up an 800RB for cheap, for a backup for my all tube heads, and I just wanted to clarify something.

Is fretster saying that when you DON'T use the biamp mode, both power amps are working together, and you're getting 400W? Or are the amps still separate and just working as dual outputs? Or does the 100W output not work at all in non-biamp mode? It seems like kind of a waste of 100W to a) not be used or b) only be used to drive a friggin' tweeter.

I have a single 4 ohm cab (610HLF) that I'd like to get the full power from the amp. I do have an old 8 ohm avatar 210 as well that I will probably experiment with, but I'd rather not lug both cabs to a gig.

 

[Frankie Fender]

I'm thinking about picking up an 800RB for cheap, for a backup for my all tube heads, and I just wanted to clarify something.

Is fretster saying that when you DON'T use the biamp mode, both power amps are working together, and you're getting 400W? Or are the amps still separate and just working as dual outputs? Or does the 100W output not work at all in non-biamp mode? It seems like kind of a waste of 100W to a) not be used or b) only be used to drive a friggin' tweeter.

I have a single 4 ohm cab (610HLF) that I'd like to get the full power from the amp. I do have an old 8 ohm avatar 210 as well that I will probably experiment with, but I'd rather not lug both cabs to a gig.

Looks like at full-range you are only using the 300 watt amp @ 8 Ohms. There is no way to bridge them and it is not recommended.

edit: I don't think the 800 will do 4 ohms so the 610hlf is not a good choice.