Can it be done?

Bacchus · Post by **Bacchus** » Sat May 17, 2008 10:02 pm

Okay, usually I play my Fender Champion 600 through my 8 ohm Marshall cabinet, even though the output on the amp is 4 ohm. It sounds pretty good. I was playing a gig last night, and using the other band's guitarist's 4 ohm Hartke mini cab. It was much better sounding, and far, far louder than the Marshall.

Basically: Is there any trickery I can do to bring the ohmage of the Marshall down to 4 ohm, or even just close to it, by wiring speakers in parallel rather than series or something? Better yet: can I do this so that I end up with two inputs on the cab, one 8 ohm for the Marshall head I use, and one 4 ohm for the Fender? Better yet again: is there any way of doing this without melting my fingers together?

Post by **Mike** » Sat May 17, 2008 10:04 pm

OK, more info needed - what is your Marshall cab? How many speakers, how many ohms each?

Secondly the reason it's louder and better is because you were getting more efficient sound transfer because of matching impedances.

Bacchus · Post by **Bacchus** » Sat May 17, 2008 10:08 pm

Mike wrote:OK, more info needed - what is your Marshall cab? How many speakers, how many ohms each?

Secondly the reason it's louder and better is because you were getting more efficient sound transfer because of matching impedances.

It's the AVT412, so four speakers, and I have no idea how many ohms each. I won't be able to open it up to check until I get back home (they cut off our internet, so I've tp post from the library), so if we could find out online that would probably be better.

I guessed that it was louder because of the matched impedances. Sounded far more open, and crunchier, and better defined, although that might have been the effects of a 410 over a 412.

Post by **Mike** » Sat May 17, 2008 10:14 pm

Let me do some research.

But if it's 8 ohms that would normally suggest 4 8 ohm speakers, wire as two series pairs of 16 ohms each then in parallel to give 8 ohms.

In that case the only way you can attain 4 ohms is to only use 2 of them.

Post by **Doog** » Sat May 17, 2008 11:31 pm

BacchusPaul wrote: I guessed that it was louder because of the matched impedances. Sounded far more open, and crunchier, and better defined, although that might have been the effects of a 410 over a 412.

I don't think impedance would have a big effect on tone- the Hartke cab is probably just better made and loaded with better speakers than your AVT jobber.

Post by **Mike** » Sat May 17, 2008 11:35 pm

Mismatching impedance does affect the sound, you get a woofy or bright sound depending which way you mismatch.

Post by **Doog** » Sat May 17, 2008 11:48 pm

Well, shut my mouth.

Post by **Mike** » Sat May 17, 2008 11:50 pm

I only learnt from trying it with teh JVM.

When I pulled two tubes, I emailed the designer to see if I should halve the impedance - as is suggested by electronic theory. He said the OT could support the same setting or half because it was overengineered, and to try both and choose the one that sounded best to me - sure enough one was a lot more woofy and undefined as I recall - the mismatched option.