Metropoulos Forum

Disclaimer: I'm a noob and sometimes do dumb things. At least nothing's on fire and I haven't fried my new 12,000 amp.

I picked up a nice cab on ebay and have been playing the new amp for a few weeks. Took me until the other night to realize I was only getting sound out of 1 side of the cab. Through trial and error I figured out the cab is wired in stereo, plugged in both outputs on the amp to both inputs on the cab, and all is happy. What I didn't consider is the cab is now 8 Ohm, not 16. No harm done...I don't think.

So...I did lots of homework and am fairly certain I can rewire the cab to parallel. I'm just unsure enough I felt the need to ask someone. I asked, and he suggested I call George. I got busy. It's now late, so here's my question.

Can someone verify, like with a picture, easy enough for this idiot to understand, how to correctly wire my Marshall cab for mono? Also, is it a bad thing to use the cab in stereo mode, like it is, and change the amp to 8 Ohms?

Thanks

Nevermind. Figgered it out.

Just to double check.....

What are your speakers impedences?

What options do you want?

What amp are you using with what output selections and do you use an attenuator, if so what load is it?

Amp is a MetroAmp 12,000 with MV, no attenuator. Speaker impedence is 16 ohms. Amp was set for 16 ohms @ 100W.

What I want to do, and what I successfully did, was re-wire the cab to mono. It arrived wired in stereo for some strange reason, and it confused me. Had to think about it for a minute.

Before re-wiring the cab, I was using both outputs on the amp, one to each side of the stereo cab. I see no reason to do that in the future, but I wanted confirmation that I should switch the amp to 8 ohms, and if it was safe to operate the rig in that fashion. But it's a moot point now. It had a funky, out of phase sound, which was cool for a minute but not something I'd want all the time.

Thanks for your reply.

Ok, just wanted to check given some of the things you said in your first post (like putting all the speakers in parallel) for the correct load.

So you rewired your x4 speakers each of 16 ohms to series-parallel arrangement or parallel-series arrangement to get an overall impedence of 16 ohms.

http://celestion.com/speakerworld/guita ... gurations/

All 4 in parallel will give you 4 ohms overall impedence which could damage your amp OT if you select the 16ohm output tap on the amp.

I've got mono wiring diagrams on my site if you need them in the future.

There are two 4x12 wiring options. The one on the bottom is how Marshall did it in the 60's. The one 2nd to the bottom is how they do it now to save wire and it makes the speakers sound a tiny bit more aggressive, but less organic than the bottom wiring diagram. Go with whatever works for you.

http://www.scumbackspeakers.com/wire.html" onclick="window.open(this.href);return false;

Thanks! Those diagrams are perfect.

I went with something a bit different...cuz this diagram is what I found, and it required changing only a couple wires.



Might be fun to experiment with different wiring in the future. For now, it works, and sounds pretty darn good, though I like the idea of a more organic sound.