Ampeg SVT400T binding posts

[sodiscomusic]

I have an Ampeg SVT400T head and an Acoustic B410 cabinet.
Ampeg input specs: http://www.ampeg.com/pdf/SVT400T.pdf

1. Mono/Bridge and Slave modes
2. 2 channels@ 200W(8 ohms) using speaker outs(2 per channel)
3. 4 binding posts(2 black, 2 red)-Bridgeable to 400W@4 ohms using the 2 red binding posts(1 positive, 1 negative)

Acoustic B410 specs: :: Acoustic - the pro's tone since 1967 ::

1. two speaker outs@8 ohms

I am trying to run it in Mono/Bridge mode so I can get the full 400W@4 Ohms. On this amp that is done by putting banana plugs in the 2 red binding posts, one positive and one negative.

This is what I have tried.

1. connected 12 gauge wire to each red banana plug(positive & negative).
2. On the other end, I have soldered the positive banana plug wire to a 1/4" speaker input connector and left the negative one unconnected, but covered the end with tape.
3. This leaves one speaker input on B410 not used.

When connecting to speaker out on Ampeg head, I get sound. But, when connecting using the binding posts and cable I created, I don't get anything.
WHAT AM I DOING WRONG? IS THE HOMEMADE CABLE NOT CONSTRUCTED CORRECTLY? IJUT WANT THE FULL POTENTIAL OF MY SETUP...PLEASE HELP!

[okcrum]

There should be a switch you need to throw to put the amp in bridge mode. It's the Slave/Mono Bridge mode switch on the rear panel.

[sodiscomusic]

The amp has sound with Slave mode engaged, but none with Mono/Bridge mode. Not sure if cable is setup right or if its something else.

[okcrum]

Both channels should still produce sound individually with the switch in either position. That switch puts one power amp out of phase with the other in Mono Bridge mode. Check your cable, should be one channel + to tip and the other channel + to sleeve on a 1/4" TS plug. If all of the above is OK, then there could be a problem with the Mono Bridge switch or the circuits it controls in the amp.

[sodiscomusic]

Originally Posted by okcrum

Check your cable, should be one channel + to tip and the other channel + to sleeve on a 1/4" TS plug.

What do you mean by "+ to tip"?

[okcrum]

Originally Posted by sodiscomusic

What do you mean by "+ to tip"?

A 1/4" TS (tip/sleeve) plug has a tip and a sleeve connection on it. If you look at the part that actually plugs in, you'll see how it's divided. The + is what you describe as the red binding post of the red/black pair on the amp output. The - would be the black binding post, which you don't use when bridging.

You want the red binding post from one channel output connected to the tip on the 1/4" and the red binding post from the other channel connected to the sleeve for bridged use.

[projectMalamute]

Originally Posted by sodiscomusic

This is what I have tried.

1. connected 12 gauge wire to each red banana plug(positive & negative).
2. On the other end, I have soldered the positive banana plug wire to a 1/4" speaker input connector and left the negative one unconnected, but covered the end with tape.
3. This leaves one speaker input on B410 not used.

Really?

You really did this?

Like, you sized up the situation and thought: "well the one terminal goes to the tip, and the other one I'll just tape up and not connect to anything. That's the ticket."

And you have a link to the manual right there in your post?

[grisezd]

I thought I was reading that wrong, had to be. But you're right, he's worked out a single conductor speaker cable.

I didn't take the time to look at the manuals, but you've got to have a complete circuit to get any signal from the amp to any speaker. I'd guess (again, didn't read it) that the two speaker inputs on the cab are in and through. Wire the taped-off end to the pole on the 1/4 plug you didn't already use and try that.

Ok, had to go read it. Yes, you have an 8 ohm cab. You can't change that without opening the box up. Just use the speaker cable you have in the 8 ohm output. If you get a second 8 ohm cab you can go back to the bridged setup with a proper cable because the two 8 ohm cabs will make a 4 ohm load.

[Jerrold Tiers]

Follow the advice from okcrum.

The speaker is 8 ohms, the outputs are 4 ohms MINIMUM...... Which means they will work FINE with the 8 ohm cab in mono...... you can't connect anything in mono that is LESS THAN 8 ohms.