SWR SM-400 Help!

[GDP]

My friend just gave me an SWR SM-400 head.I want to run it in bridge mode with the banana jack.However, usually there is a black & red input.Mine has both red ones.I noticed it read on the bottom input of the banana jack "Do not reference to ground" Sorry if this sounds like a dumb question but is the postive top & negative bottom or vise versa????I just want to make sure seeing my friend can not remember...Hopefully someone can set me straight, thanks in advance.

I can take a picture if need be.

 

[father of fires]

Bridging works by putting a positive and negative signal through the speaker cab where as a regular output jack just has the signal and a ground. Its like the difference between balanced and unbalanced, guitar cables and mic cables, etc. So what I'm getting at is that it shouldn't matter what direction the cable is plugged in because it does not need a ground when simply going from amp to cab. Don't try any crazy cab setups with multiple cables and cabs and you should be fine.

But if you have a multimeter you could set it for continuity check and the banana plug that is connected to the sleeve of the 1/4" jack would be the nominal "ground".

Edit: If you have no issue waiting I can test this out at practice on my SM400s in a couple of days. I have a banana cable that is White and Black and the plugs on the head are Red and Black. I've always gone White/Red and Black/Black but have never thought about +/-, positive/ground, top/bottom, etc. So, I can flip the cable around and see if I'm right before you blow your amp!

 

[B-string]

The banana jacks are for bridged mode only. The lower one should be the negative swing (note I did not say ground).
BTW I think it will be an 8ohm min load only, no 4ohm loads.

 

[will33]

There should be a + and - banana jack. Let me dig mine out of the closet. Those replacement, screw on banana locks are cheap. Somebody may've just got a replacement in the wrong color.

 

[will33]

Crappy pic but your top is + or red, and your bottom is - or black. Put the + speaker lead in the top, - speaker lead in the bottom, and flip the switch to the right of the fuse to "bridge, 500 W, mono".

 

[GDP]

Perfect & thanks for the quick responses all......

 

[Jim C]

Mine has been in bridge mode only since I bought it new in 1986!

 

[will33]

Mine has been in bridge mode only since I bought it new in 1986!

Now, that's a testment to.....something.

 

[iammr2]

The banana jacks are for bridged mode only. The lower one should be the negative swing (note I did not say ground).
BTW I think it will be an 8ohm min load only, no 4ohm loads.

8ohm is the optimum operating condition in bridged mode. You can run 4ohm and the amp will run hot. No 2ohm in bridged mode.

 

[lowendrv]

Maybe this will help
Link Removed

 

[Jim C]

Now, that's a testment to.....something.

SWR SM400 - Built like a tank and runs hot enough to cook on!

 

[chadds]

Flip the switch!