Bridging amps

[jmiles45]

Hey guys! Hoping someone could possibly help me out here on this question. I've heard alot about people pairing up amps and such to power multiple cabs since the head isn't 2ohm capable and such but how is this accomplished? I'm confused about the whole effects send return etc as a way to link up heads but if someone could explain it further that would be great.

I have an Epifani ps 400 which has an effects send and return and also a preamp out and I also use a GK 800rb which typically I use to power an epi 210 but I use my ps 400 to power an epi 410. If I ever needed both cabs for a larger gig could I pair up these two amps?

[jmiles45]

Bump

[jensdandanell]

I would be interested in hearing about this too.

[jelwood]

Well shoot, so much for the techs getting this one.

Personally, I have never done it myself, but I've read about this in a lot of places. I know that if you have two GK amps you just need to connect a cable going from the effects send from one amp to the effects return of the other. I would imagine that just doing this would work for any other amp as well as long as the effects loops have the same design as the GK ones. You'd probably have to find the block diagram for your 800rb and other amp and see if the effects loops match up for your two heads. Also, try sticking one end of a 1/4" in the effects send of your non GK amp, but don't plug the other end of the cable in anywhere. See if you can still get a signal out of the head to your cabinet like you always do without the 1/4" plugged in. If you do get sound, you should be good to go. Then you just plug the other 1/4" head into the 800rb's return.

[Growly Lytes]

Heres a link about how to link 2 poweramps together.Im not sure if this applies to you though ?
http://www.youtube.com/watch?v=V_0gz...os=MZzdcO1IHo8

[chuck3]

definitely works that way with Genz Benz gear. I have done it a couple of times for indoor-outdoor gigs or sprawling situations like poolside parties. I am using an LM II as my main head these days, need to see if it can do the same thing with a Genz Benz, now that the warm weather is here and some of the gigs are going back outdoors.

[rbonner]

I see this was up 24 hours. It must have wingged its way down the page pretty quick, I usually just respond on stuff that interests me on the first page. My last thread started has 100 views and no responses, so don't feel bad.

What I do. I own a Radial JD-7. Its rather expensive though. I'm just rebuilding my big amp and making it smaller. The problem with Y cording or jumpering between send and receives or even preamp outs and power amp ins is ground loops. Sometimes it works, sometimes all you get is 100DB of hum.

My JD-7 was supposed to be a guitar level amp multiplier, but the preamp outputs on AMPEG amps is Point 5 Volts, not the usual 1.25V of most PA amps. They proprietorilly moved one amp stage from the preamp over to the amplifier... This is fine if you use a high output preamp, but keeps you from using an AMPEG Pre without modifying it.

Anyway, what I did with my previous big rig is come out of the SVT-4PRO's preamp output to the guitar input on the JD-7 and then on amp output #1 I went to the amplifier input back on that same amp. The Output #2 to the amp input of amp #2 and so on through amplifer #6.

The end result since the JD-7 uses Jensen stage isolation transformers and class A unity gain amplifiers; I'm able to drive six 1200W amplifiers with zero hum and buzz.

So.

Radial makes a little two horse unit like mine... Consider buying one. You can use the Bass right to the input and outputs as designed; or try the preamp out to amplifer in on the second amp. If the voltage doesn't go too high you won't clip out the unit.

Back when I was a kid we just used Y cords. BUT again, you introduced hum. Things would really go crazy with the switchable polarity amps. You needed to make sure they were switched the same before connecting the Y cords.

Even on my ampegs, when coming out of the preamp out and jumpering to the amp in on the second amp, I get some hum.... The radial eliminates ALL...

http://www.radialeng.com/di-jd7.htm

On the rebuild of the big amp I have removed all six of the SVT-4PRO's and they are for sale BTW... and replaced them with four SVP1600's power amp only sections of the 4PRO and a single AMPEG preamp. I only did this to get the $1300 dollar amplifiers out of the rig and replace them with more inexpensive amps only with one preamp.

BOB

[agedhorse]

First of all, the title of this thread is a little misleading, bridging a power amp is an entirely different subject.

Using 2 power amps with a preamp is different and fortunately easier to explain. A preamp signal is typically about 1 volt. A power amp amplifies this up to whatever voltage is necessary to deliver the rated power, as well as amplifies the current so that the voltage can deliver adequate current to the speaker. Power = voltage x current.

With the Genz Benz amps, this is done in a simple manner. All of our amps have an insert point (called a serial effects loop) where the signal path can be broken between the preamp and the power amp. It's primary function is for the insertion of a compressor, but it's secondary function is so that the output of the preamp can then drive the input of a second power amp.

Using the Shuttles as an example, doubling up is easy where you take a 1/4" patch cable and using Shuttle #1 as the master come out of the preamp out (effects send)into the power amp in (effects return) of Shuttle #2. The volume controls are set up so that each amp's master volume works and this allows for balancing levels between cabinets. A seperate cabinet must be used with each amp.

Other manufacturers also do something similar to this, but read the manuals carefully since there are different ways this work depending on the choices each manufacturer makes.

[chuck3]

Six 1200 watt amplifiers ... I am in awe!

[chuck3]

Seriously, I have posted with agedhorse about this before, and if you are interested in doing this with absolutely no problem and perfect results, having two Genz Benz Shuttles will get you there. I've done it several times.

[rbonner]

Andy, With my AMPEG's I've had issues with hum doing it that way. That's why the JD-7 in my case. WHat magic do you guys do inside to eliminate ground loops and hum... Is there an isolation X-fmr in there or some other magic?

BOB