GK 800RB biamp cable question

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ambissonnett

Jan 9, 2013
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#1
Hey guys,

So I recently purchased a GK800rb, and absolutely love it. I own two 410 rbh cabinets, and one 115rbh cab.

Now I've heard/read all the information of mixing speaker sizes, which is why I want to try biamping if I choose to have the 115 in my rig. If not, I'll just run the two 410s in full range.

My question is, what type of cable would I have to use since the 800rb doesn't have the speakon cable insert for biamping?

Can I just run a standard speaker cable from the head into the full range insert on the cabinet, while having the biamp feature turned on on the head? Or is there a cable out there with one end a speaker cable, and the other end is a speakon insert?

Kinda stumped on this, all help is appreciated.

Thanks!
 
#2
The 800RB lower amp can run at 4 ohms (300 watts), so IF your 410 cabs are 8 ohms each you can just run a speaker cable from the appropriate 'speaker out' to them, and the 'upper' amp ONLY operates into an 8 ohm load (115 cab?), so run a speaker cable into that from the 100 watt amp and then control your blend from the front panel ... ;)
 
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#3
Oh yeah. Sorry, forgot mention all cabs are 8 ohms. I tried that, and the volume to me just felt off. Is that just because the 410 is 800 watts, and the 115 is only 400 watts? Or would the biamp help me balance this out?

I did a couple volume tests. I plugged both 410s in full range and it sounded absolutely killer. I then tried a 410 and 115 mixed, and the volume went down a decent amount, even dimed out (I think, not 100% sure that being a week ago).

I also just plugged straight into the 115 to hear that by itself. I was in full range for that, and I had my 800 dimed out and the volume still wasn't ear piercing. Is that normal for the 115? I'm hoping nothing is wrong with the cab.

Sorry, new to biamping and still trying to figure everything out.
 
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#4
I have never ran a stack like your three cabs using both amps on an 800RB, but did use both amps to power three identical 8 ohm 210 cabs, two on lower amp, one on upper amp ... I guess I never felt the need to continue running it that way, and just used the head with a pair of 210's at 4 ohms/300 watts ...

What you may be hearing is the affect of mixing the two types of cabs, or you may have an issue with the 115 ... try running the 115 with one of the 410's out of the main amp and see what you get ... BUT, it sounds to me like you answered your own question on how to use the head when you said ... "I did a couple volume tests. I plugged both 410s in full range and it sounded absolutely killer." ;)

I have seen more than a few 800RB's out there that folks had blown the top amp, likely running it at a 4 ohm load ... I never really felt the need to use it during my love affair with the 800RB ...
 
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#5
I believe you should be fine! Mixing cabs is probably throwing everything off.

Low side will give you 300 watts @ 4 ohms. Which gives each 410 cab about 150 watts.

Hi side is 100 watts @ 8 ohms which your 115 is getting 100 watts.

This setup will work but might not sound right. Make sure you turn off biamping to see if you get full power first, then press biamping and sweep the frequency around!

EDIT: by turning on biamping, your 115 should sound more trebly or midrange. Biamping will cut the lows on the hi side which creates a hi-pass filter.
Maybe this is why it sounds off.
 
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#7
tjh said:
The 800RB lower amp can run at 4 ohms (300 watts), so IF your 410 cabs are 8 ohms each you can just run a speaker cable from the appropriate 'speaker out' to them, and the 'upper' amp ONLY operates into an 8 ohm load (115 cab?), so run a speaker cable into that from the 100 watt amp and then control your blend from the front panel ... ;)
Click to expand...
^^^ Do this, but leave the bi-amp or crossover switch OFF (this will run both amps in full-range.) You'll be putting the most power to the most speakers (the two 210's) and the lesser power into only one speaker (the 115). Try that and report back with volume.

Also, are you running your master wide open and using the input volume to control the overall sound level?

Raz
 
#8
I'll test this option next time I head to our practice space, which should be tomorrow. I know I've had all three cabs plugged in at the same time in full range, and noticed the 115 wasn't as loud. Obviously, do to mixing cabs.

This raises my next question. Would any damage occur is have I have my speaker cables plugged into full range mode on my cabs, while having the biamp mode engaged on my head?

Also, is the best combination having the two 410s in the 300 watt channel, and the 115 in the 100 watt channel? Or does it matter if I have the 115 put in the 300 watt channel?

And one more point, sorry to drag this out. Any idea on how much volume, if any, is lost if I have the 115 stacked the middle of the three cabs? Since its raised off the floor.
 
#9
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#10
You need heavy gauge, shielded speaker cables with 1/4 inch on the amp end, and whatever your speaker has on the other. If that is speakon, ask your local music supplier to trade a 1/4 inch end for a speakon.

I found the most important aspect of biamping on the 800RB was the crossover. Optimal sound requires some diligence with the frequency and balance.

To find the correct frequency, put the amp into biamping mode, then alternately plug in just the high speaker then low speaker. Play and adjust the frequency until you are happy with the spectrum coming out of each side. To find the correct balance, same thing--listen to each side independently before combining.
 
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#12
You don't need "shielded" cable EVER for speakers. If you want to use "heavy gage" wire no harm, but really 18awg for the high amp (100watt) and 16awg for the low (300 watt) is more than enough unless you plan on 50 foot cables.

Sounds like you have a problem with the 115RBH. While only half as "loud" as the 410 (due to speaker displacement area) it should be pretty healthy. If you lose volume when adding it to the 410s that indicates the 115's speaker polarity is reversed and if a used cab may not even have the correct speaker in the cab.
 
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