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Using Two Combo Amps

GWGuitar

GWGuitar

Jul 25, 2021
412
764
Oklahoma
www.gregorydwest.com
#1
Hi folks. I have a question for you experts out there. I have never gigged in any situation where I needed anything larger than a combo amp. If I needed more "oomph" I just ran out of a D.I. from my pedalboard or out to the FOH from the line out of my amp. I was just wondering, theoretically (because I don't have a practical need to do this right now), could I add a second combo amp and get the same coverage as having a larger amp and multiple cabs? I'm mean, would two 100-watt combos give the same coverage and output as a 200-watt amp? I mean, I have a perfectly good combo and I would rarely use anything bigger. But if I had "Combo A" at home and "Combo B" at a rehearsal location, and I needed to cover a larger gig, could the two be used together, either by feeding the line out from one to the other, or by splitting off the stereo outputs of my rack's mixer? Just wondering.....
 
#2
Adding an identical combo amp should give you +6dB. Increasing the power from 100W to 200W alone will only give you +3dB. This is somewhat of an oversimplification as it's likely that a 200W combo will have a different speaker than a 100W combo.

Another possibility may be adding a matching extension cab. Some combos can run an extension and some cannot.

The gain in SPL depends on how the amp responds. Some amps produce the same power when an extension is added. This condition will produce +3dB. Some amps double the power when an extension is connected. This condition will produce +6dB. Other amps increase power, but only by 60%-70%. This condition will produce +4 to +5dB.

As far as how to connect two combos, it depends on the amp. One option is to use a Y cable to feed a signal to both preamps.

The next option is to run a link from the input of one amp to the other. If an amp has two inputs on a single channel this often works. The signal is essentially going in one input and out the other. How well this works depends on how the jacks are wired.

Some amps are actually intended to be slaved, so one preamp controls both. There may be a line out/slave out, or an Effects Send may also be used for this. The output is plugged into an Effects Return or power amp in. You may need to adjust the Master on both amps, but usually usually the second preamp is totally bypassed, so you only need to adjust gain and tone on one amp.

One problem you may encounter is hum. Unfortunately connecting amps sometimes causes ground loops. So this is something you should work out before gig day, to make sure it will work well.
 
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#4
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@GWGuitar, I can't conceive of a better answer to your question than that posted by @Wasnex above. :thumbsup:

This a perennial discussion in the Fender Rumble Club and we've collected some of the best posts on the subject on the Club's Wiki page.

Old Garage-Bander said:
I always wondered about tying something like four Rumble 100's together via the send/returns.
A scaleable solution for about any venue and failover with not a lot of loss in capability if one died. :cool:
Click to expand...


That would be super cool, Garage! But, the most I've ever come across is the four Rumble 25s of @b-b-b-bass. :woot:

b-b-b-bass 4x25 rig.jpg
.
 
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#5
GWGuitar said:
Hi folks. I have a question for you experts out there. I have never gigged in any situation where I needed anything larger than a combo amp. If I needed more "oomph" I just ran out of a D.I. from my pedalboard or out to the FOH from the line out of my amp. I was just wondering, theoretically (because I don't have a practical need to do this right now), could I add a second combo amp and get the same coverage as having a larger amp and multiple cabs? I'm mean, would two 100-watt combos give the same coverage and output as a 200-watt amp? I mean, I have a perfectly good combo and I would rarely use anything bigger. But if I had "Combo A" at home and "Combo B" at a rehearsal location, and I needed to cover a larger gig, could the two be used together, either by feeding the line out from one to the other, or by splitting off the stereo outputs of my rack's mixer? Just wondering.....
Click to expand...

Theoretically, yes. The "best" way to do this would be two identical combos.


That said, we could help you a lot more if we knew which combo you already have.
 
#6
Everything @Wasnex said (always—such a resource :thumbsup:) and:

If both combos have available 1/4” outs and at least one of them uses a conventional 1/4” plug in one of those outs to connect the amplifier to its own speaker(s), you can unplug the speaker(s) of one combo and power it/them with the other using a male-to-male 1/4” coupler between the cable coming out of one amplifier and the cable going to the speaker(s) of the other.
 
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#8
GWGuitar said:
Hi folks. I have a question for you experts out there. I have never gigged in any situation where I needed anything larger than a combo amp. If I needed more "oomph" I just ran out of a D.I. from my pedalboard or out to the FOH from the line out of my amp. I was just wondering, theoretically (because I don't have a practical need to do this right now), could I add a second combo amp and get the same coverage as having a larger amp and multiple cabs? I'm mean, would two 100-watt combos give the same coverage and output as a 200-watt amp? I mean, I have a perfectly good combo and I would rarely use anything bigger. But if I had "Combo A" at home and "Combo B" at a rehearsal location, and I needed to cover a larger gig, could the two be used together, either by feeding the line out from one to the other, or by splitting off the stereo outputs of my rack's mixer? Just wondering.....
Click to expand...

I have two Eden 320 watt combo amps and have used the both paired together often. It’s a formidable rig. Not as good as the Eden World Tour series gear, but it’s a solid weekend warrior outfit.

I see no reason not to to buy a second combo and slave one.
 
#12
Actually, modern big traveling PA systems for big touring shows operate exactly that way: Each bin is self-powered, and you add as many as you need to reach the desired SpL for a given venue. A far cry from the old days of flying the cabinets, only to be hooked up to racks and racks and racks of stereo power amps and miles of speaker cable.
 
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#13
I have been trying to slave my two new GR Bass 212 Slim combos, but so far no dice. I have tried going out of the master combo's effects send into the slave's main input or effects return, but in both cases the primary combo mutes itself. The only other option is to try the master DI XLR output into the slave main input/effects return, but I have to get an adaptor cable for that.
GRBCombo02.jpg
 
#14
pingvuiini said:
I have been trying to slave my two new GR Bass 212 Slim combos, but so far no dice. I have tried going out of the master combo's effects send into the slave's main input or effects return, but in both cases the primary combo mutes itself. The only other option is to try the master DI XLR output into the slave main input/effects return, but I have to get an adaptor cable for that.
View attachment 4818416
Click to expand...
try this
Hosa YPP-106 Y Cable - 1/4 inch TS Female to Dual 1/4 inch TS Male
 
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#15
Old Garage-Bander said:
I always wondered about tying something like four Rumble 100's together via the send/returns.
A scaleable solution for about any venue and failover with not a lot of loss in capability if one died. :cool:
Click to expand...
Not sure you could do that because when you use the Effects-in/return, you are totally bypassing the preamp of the slave amp. You are using the preamp from the 1st amp, the "master amp" and delivering that to the power-section only of the 2nd amp, the "slave amp". So the effects send/out of the second amp is not going to have a signal to connect to the power section of the 3rd amp, let alone the 4th.

Actually, depending on how the amp is wired, you might be able to do that. If so, then the 2nd rumble's preamp would be running into the power section of the third amp and the third one's preamp would be running the power section of the 4th. It "might" be possible. If they were all Rumble 100's you could theoretically use the same settings on the first three amps to get close to the sound from the first. Of course you'd have to balance all 4 master volumes...that would really be a mess. And God help you if you have to track down a hum.o_O
 
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#16
pingvuiini said:
I have been trying to slave my two new GR Bass 212 Slim combos, but so far no dice. I have tried going out of the master combo's effects send into the slave's main input or effects return, but in both cases the primary combo mutes itself. The only other option is to try the master DI XLR output into the slave main input/effects return, but I have to get an adaptor cable for that.
View attachment 4818416
Click to expand...
I ran into that problem with my Eden Nemesis RS400 when I first got it back in 2008. The problem you're running into is that you are sending the signal out of the first one just fine and it's running your slave amp like it's supposed to do, but the signal return on the master amp is not getting any signal it back in. A simple Y-cord will fix that. Plug the Y cord into the effects-send and then run one short cord right back into the effects-return on that first combo. Run the second line from that Y-cord into the effects-in of the your second combo and everything should be working.
 
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#20
G-Dog said:
.
the most I've ever come across is the four Rumble 25s of @b-b-b-bass. :woot:
.
Click to expand...
AAAAAAAAAAH! That is so cool!!:D Gives me White Stripes vibes.
I've done some similar things, like running 2x ampeg mini svt's + 500w/410.
Just the other day I met another bass player who likes multi amping/cabbing. She ran 3 cabs too. First time meeting anyone else who does that (besides here on TB that is)

I made a thread similar to this one when I first started getting into it, got a lot of great advice. I'll see if I can find it somewhere and link.
But basically, yes it works. There are a ton of factors to consider, like placement, speaker sizes etc etc, so if you want you can really nerd out about it:D
 
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