One cab - Two head - Different ohms

dean · February 21st, 2006, 01:51 AM

OK, so I picked up an old Fender blackface era 2x12 cab for cheap. It has a couple holes in the grill cloth and a 3"x8" port cut out for the back. I figured $75 wasn't bad for the cab in this condition. It will house a couple 8 ohm speakers for now.

I have two amps that I want to run through the cab (not at the same time), but one is rated at 4 ohms (Bandmaster Reverb) and the other is rated at 16 ohms (Galien-Krueger 250ML). Can I wire the cab up with some sort of switch that will give me the option of making the 8 ohm speakers work with both amps? Or can I wire the speakers to two separate 1/4" jacks - one 4 ohm and one 16 ohm? I can make a control/jack/switch panel that will fit over the hacked "port" already in the back panel.

Is this possible? Are there any sites that might have a diagram and instructions for wiring something like this? I need pictures or diagrams if possible - I'm sorta technically "needy" when it comes to this.

Thanks for any help!

Dean

Ben Harmless · February 21st, 2006, 02:06 AM

Aw, heck yeah. You need a series/parallel switch. You're lucky in that you don't need an 8ohm impedance anywhere.

I'm not finding a good diagram of the switch anywhere though. I'll keep looking a bit, but now so can you. 8)

dean · February 21st, 2006, 02:14 PM

This is a diagram from this site. This is the Mono, Switchable Impedance diagram. Is this what I want to do? And do I use the two jacks for the different ohm ratings? (I'm not sure I understand the "IN" - "OUT" jacks unless that deals with linking other cabs to this one.)

Again, any help is appreciated.

Dean

CancerLeoCam · February 21st, 2006, 02:49 PM

...get a Weber Z-Matcher and not mess with the cab.

Bluesbob · February 21st, 2006, 04:26 PM

Your diagram is just what you need. As you figured out, the jacks are "parallel" so you can piggyback. I wish I could help you with parts numbers and such, maybe someone else? Radio Shack? Anybody know?

February 21st, 2006, 01:51 AM	#1 (permalink)
dean Friend of Leo's Join Date: Mar 2003 Location: Twin Cities, Minnesota Age: 60 Posts: 2,042	One cab - Two head - Different ohms OK, so I picked up an old Fender blackface era 2x12 cab for cheap. It has a couple holes in the grill cloth and a 3"x8" port cut out for the back. I figured $75 wasn't bad for the cab in this condition. It will house a couple 8 ohm speakers for now. I have two amps that I want to run through the cab (not at the same time), but one is rated at 4 ohms (Bandmaster Reverb) and the other is rated at 16 ohms (Galien-Krueger 250ML). Can I wire the cab up with some sort of switch that will give me the option of making the 8 ohm speakers work with both amps? Or can I wire the speakers to two separate 1/4" jacks - one 4 ohm and one 16 ohm? I can make a control/jack/switch panel that will fit over the hacked "port" already in the back panel. Is this possible? Are there any sites that might have a diagram and instructions for wiring something like this? I need pictures or diagrams if possible - I'm sorta technically "needy" when it comes to this. Thanks for any help! Dean __________________ "I used to be clueless, but I've turned that situation around 360 degrees."

February 21st, 2006, 02:06 AM	#2 (permalink)
Ben Harmless Friend of Leo's Join Date: Mar 2003 Location: Albany, NY US of A Posts: 3,375 12 Photos	Aw, heck yeah. You need a series/parallel switch. You're lucky in that you don't need an 8ohm impedance anywhere. I'm not finding a good diagram of the switch anywhere though. I'll keep looking a bit, but now so can you. 8) __________________ "I think I'll go for the life of sin, followed by the last-minute, presto-change-o, deathbed repentance." - B. Simpson

February 21st, 2006, 02:14 PM	#3 (permalink)
dean Friend of Leo's Join Date: Mar 2003 Location: Twin Cities, Minnesota Age: 60 Posts: 2,042	Here's a diagram - will this work? This is a diagram from this site. This is the Mono, Switchable Impedance diagram. Is this what I want to do? And do I use the two jacks for the different ohm ratings? (I'm not sure I understand the "IN" - "OUT" jacks unless that deals with linking other cabs to this one.) Again, any help is appreciated. Dean __________________ "I used to be clueless, but I've turned that situation around 360 degrees."

February 21st, 2006, 02:49 PM	#4 (permalink)
CancerLeoCam Tele-Afflicted Join Date: Jul 2005 Location: Mule Deer-Mt. Lion Safari, CA Posts: 1,692 5 Photos	You can always..... ...get a Weber Z-Matcher and not mess with the cab. __________________ Everyone's your "buddy" or "friend" when they want you or something from you. If you're not willing to work for free why should somebody else?

February 21st, 2006, 04:26 PM	#5 (permalink)
Bluesbob Tele-Afflicted Join Date: Mar 2003 Location: East Suffolk L.I. Posts: 1,073 20 Photos	You got it... Your diagram is just what you need. As you figured out, the jacks are "parallel" so you can piggyback. I wish I could help you with parts numbers and such, maybe someone else? Radio Shack? Anybody know? __________________ What, me worry?