How to rewire speaker extension for a combo from parallel to series?

wyleeboxer · #1 06-09-2010, 12:09 PM

I installed a 4ohm speaker in my combo to replace my 8ohm speaker so I can get the full wattage out of the amp when just using it as a combo... but since the internal amp can only run a 4ohm minimum load I can no longer use the extension output for another cab. How would I rewire the extension output into series in case I need to run another cab, and do I need to rewire the internal speaker/tweeter as well for series?
I know my wattage will drop but at least the output for another speaker would be usable. thanks

Bardley · #2 06-09-2010, 12:17 PM

I don't really know if there is a way to do that without both speakers hooked up. The speakers would need to be wired in series with each other rather than each speaker wired in series internally. If you wired the extension jack in series with the internal speaker you would get no output because the jack would be an open circuit. Without something plugged into the jack (another speaker) you would not complete the circuit.

Rick Auricchio · #3 06-09-2010, 12:20 PM

It sounds like you want to revert to what you should have done in the first place...add the second 8-ohm cabinet.

So do the simplest thing: Put back the original 8-ohm speaker and you're done. Don't have the speaker? Buy a replacement from the amp manufacturer and sell the four.

This also solves the problem of the crossover, which was designed for an 8-ohm woofer. When you changed to four ohms, you probably didn't realize that the crossover wasn't working as designed any more.

wyleeboxer · #4 06-09-2010, 12:25 PM

Well I do want both speakers hooked up and to run in series mode when I plug into an extension cab... if that makes sense? Like the older Nemesis combos that would run in series when you plugged into another cab (although less wattage output from the amp would be given) and when unplugged (or not using the external speaker output) the internal speaker was getting the full wattage allowed from the amp. Thanks for anymore help!

mcapote · #5 06-09-2010, 12:27 PM

for series you would have to run the + of 1 cab to the - of the other but you would need to use the other + and - to run to the input, so you would literally have to wire it like banana plugs on the backs and run wires between the cabs to get the wiring you want.

Rick Auricchio · #6 06-09-2010, 12:30 PM

Having full wattage to the internal speaker is probably unimportant. Virtually all speakers will fart out LONG before you hit them with their full power limit.

If the amp isn't loud enough with the internal speaker, that's why you add a second cabinet.

Series wiring adds complexity, probably requiring specially-wired speaker cables. If you ever accidentally use a standard cable, the cabs end up in parallel. When that happens, your amp will be REALLY loud for a VERY short time. Do you want to take that risk?

And the crossover on the internal speaker is still wrong at four ohms.

Just go back to the original speaker configuration. If that doesn't float your boat, then perhaps it's time to consider upgrading to a different rig.

Just to keep things interesting, what brand and model of combo are we talking about?

pbd · #7 06-09-2010, 12:34 PM

you can check out these Y cables and see if they will do what you want, they can be ordered as serier wiring and can also be made with speakon plugs

http://procablesnsound.com/items/Pow...ables/list.htm

Todd

Rick Auricchio · #8 06-09-2010, 12:35 PM

Yes, a special speaker cable can be used. Until you find it one day it goes bad when you're setting up. Then what do you do?

Zooberwerx · #9 06-09-2010, 12:36 PM

Quote:

Originally Posted by Rick Auricchio

It sounds like you want to revert to what you should have done in the first place...add the second 8-ohm cabinet.

So do the simplest thing: Put back the original 8-ohm speaker and you're done. Don't have the speaker? Buy a replacement from the amp manufacturer and sell the four.

This also solves the problem of the crossover, which was designed for an 8-ohm woofer. When you changed to four ohms, you probably didn't realize that the crossover wasn't working as designed any more.

What Rick said.

Riis

wyleeboxer · #10 06-09-2010, 01:08 PM

I actually have a 3 year old Nemesis RS115 combo (yes this combo unlike the old Nemesis combos are wired in parallel not series) that came with the 8ohm stock speaker running at 220watts, with another 8ohm speaker cab it would run at 340watts which worked great, but Ive got my other SWR350/212 Eden rig for bigger shows and that I use for most of my other gigs. So, I thought to get bit more bottom and headroom out of the combo I would install a Carvin NE15-4 600W Neodymiun 15 Inch 4ohm Woofer in the combo giving the speaker the full 340watts and a speaker that wouldnt fart our as quick on its own, and it actually worked great and I allows me just that little bit more out of the combo on its own to be more usable at some of the smaller/medium clubs we plat at. I now just want to make use of the extension cab output on the combo back panel in case I ever (but probably wont) had a need to use it?

wcriley · #11 06-09-2010, 01:23 PM

No special cable required. The MusicMan amps from the late 70s had speaker jacks wired in series rather than parallel. They used a shorting jack, if I remember correctly.

Try to find a schematic for a MusicMan 130HD or 65HD. That should show you how to do it.

wyleeboxer · #12 06-09-2010, 02:27 PM

thanks for all your help guys! I think Ill give Eden a call a see if they have a schematic for their older Nemesis combo's that are wired in Series? Thanks again

Rick Auricchio · #13 06-09-2010, 04:08 PM

Quote:

Originally Posted by wyleeboxer

I now just want to make use of the extension cab output on the combo back panel in case I ever (but probably wont) had a need to use it?

I've wasted a mountain of cash buying flexibility to do things I've never done. It's great to know you can do something, but when you never use that flexibility, it's just more money spent...

Beware that the speaker jack(s) may attach directly to a circuit board. That increases the modification effort (and risk) considerably.

wyleeboxer · #14 06-09-2010, 04:29 PM

Quote:

Originally Posted by Rick Auricchio

I've wasted a mountain of cash buying flexibility to do things I've never done. It's great to know you can do something, but when you never use that flexibility, it's just more money spent...

Beware that the speaker jack(s) may attach directly to a circuit board. That increases the modification effort (and risk) considerably.

Aint that the truth!

Good thing is I dont believe the jack is mounted to the circuit board. I might end up just putting a plug in the output jack if I dont think its worth the mod? Thanks again!