# bridge

Discussion in 'Amps and Cabs [BG]' started by spalka621, Nov 8, 2005.

1. ### spalka621

Jul 26, 2005
Minneapolis, MN
it i buy a power amp and am running 2 gk 8 ohm cabs how do you bride them and wwhat doe sit do.

2. ### Eric Moesle

Sep 21, 2001
Columbus OH
Say whaaaa?????

Aug 24, 2005
Houghton, MI
You don't bridge cabs - you bridge an amp. Bridging basically takes the output from the "+" terminal of each channel of the amp (running 180 degrees out of phase - that's what the bridge mode switch on the amp does) and using it as a single, higher powered channel. In this case, you would run from Left + and Right + on the amp to the pair of cabinets in parallel. Note that the amp channels each see HALF the load presented, so if you are running two 8 ohm cabs (for a 4 ohm load) the amp MUST be able to tolerate a 2 ohm load on each channel, or it will not function correctly setup this way.

- Tim

4. ### nashvillebill

Don't you mean "the amp must tolerate 2 ohms per channel, to equal a 4 ohm bridged load"....

Aug 24, 2005
Houghton, MI
Yeah . . . . I was tired and having verbal dyslexia . . . . but I was trying to relate the need for each channel to be able to handle half the impedance of the load that is connected in bridge. Thanks . . . .

(I edited my prior post for clarity as well . . . .)

- Tim

6. ### DLM

May 25, 2004
California
So my Stewart 1.2 will do 1,200 watts bridged @ 4 ohms. If I run a cable from the amp to one 8-ohm cab, and then run another cable from that cab to another 8-ohm cab, will I have a 4-ohm load?

Also, power drops to 200 watts per channel @ 8 ohms. So, is the choice...

Either run amp bridged into two 8-ohm cabs and each cab will "see" 600 watts vs. 200 watts when channels are run individually? Is this a correct understanding?

Aug 24, 2005
Houghton, MI
Sounds like you have it figured out. The multiple connectors on most all speakers are just a loop through, so pluggins two as you describe will give you a 4 ohm load, and the 1200w from your amp, vs. the 200+200. You have just discovered the primary reason for bridging - (in the voice of Tim
Allen . . . . ) More Power!

- Tim

8. ### DLM

May 25, 2004
California
I've seen where someone has taken a banana plug and put it into another banana plug that's connected to the amp. I'm guessing each cable goes to each cab.

In what cases would you want that?

Is that the same effect as running a cable into one cab and then another cable from that cab to another?

9. ### kelbrihanBanned [Deceiving users with multiple usernames]Inactive

Dec 2, 2004
So are you Tonto, Frankenstein or Tarzan?

10. ### kelbrihanBanned [Deceiving users with multiple usernames]Inactive

Dec 2, 2004
Or maybe the Incredible Hulk? " Hulk no like, smash GK" heh heh

Aug 24, 2005
Houghton, MI
Dead on identical to daisy chaining cabinets. You would do the bananna plug thing if you had marginal cables, since each would only carry half the power, as opposed to the first run carrying it all if you daisy chain cabs, and also if the cabinet did not have loop through jacks. Either way is electrically a parallel connection.

- Tim

12. ### violatedpplGuest

May 8, 2005
san fran bay area
its it ok to bridge with 1/4 cables, the amp I am trying today only has spekon and bannana plugs and my cab only has a 1/4 input although In the future I will put a spekon plug on it. so its it ok to bridge going to bannana to 1/4 in without the end result of me having a shocking experince.

Aug 24, 2005
Houghton, MI
You can do it, but the outer shell of the 1/4" connector will be in the order of 50 or 60 volts or so above ground, depending on your amp power. Not terrible, but the potential for getting a shock is there . . . . . but unless you like to hold the connectors while playing, the risk is minimal. Just don't plug/unplug while playing/powered on, and all should be OK. You might also want to wrap the outside of the speaker end 1/4" jack with electrical tape, if you are really worried.

- Tim

14. ### steveksux

Mar 23, 2005
Detroit area, Troy, MI
Not so much of a problem giving you a shock, but say people run cables behind your amp. The shield on the 1/4 " jack for the pa is grounded. If it happens to hit the metal shield on your cab which is 50 or 60 volts, you short out your power amp to ground. Not a good idea.

The 50-60 volts won't give you much of a shock, but you will be very shocked when the magic smoke comes out of your amp from shorting the output!

Randy