Marshall Amp Forum - View Single Post - 1960A 4x12 cab re-wiring issues (16ohm)

petejt · 04-06-2008, 10:31 AM

Hi folks, this is my first post here.

I'm a regular at Harmony-Central though.

Anyway, I have a bit of a dilemma. Hopefully I won't seem too long-winded.

I have a Marshall 1960A 4x12 cab, that is connected to my Engl Fireball 60watt valve amp. The Fireball has the capability of outputting to two 16 ohm cabs.

I am currently in the process of modifying the cab so it is a "semi-Leslie" cab.
Basically it will have two 'static' 12" speakers, and then either one or two treble drivers with rotating horns, for chorale effects.

The 12" speakers are Electro Voice, 8ohms each.

The treble driver/s are 16 ohms.

I know that I can wire the EV speakers in series so that total impedance will be 16 ohms.

And, I know I can have just one treble driver on its own, at 16 ohms, or have two drivers wired in parallel, so that total impedance will be 16 ohms.

That way, all the impedances will be the same.

But, how will I wire up the jackplate?

As I said earlier, I can hook up two 16 ohm cabs, or "cabs" (ie two connections to 1 cab?) from the Fireball amp.

I am a bit muddled, as you can see.
Would it be best to just get another normal 1960A jackplate, set it to 16 ohms mono, and use that one to connect to the driver/s? And then use the other jackplate, set to 16 ohms mono, for the EV speakers?

Or is there a more efficient way I can do this?

04-06-2008, 10:31 AM	#1 (permalink)
petejt Junior Member Join Date: Apr 2008 Location: Perth, Western Australia Posts: 4	1960A 4x12 cab re-wiring issues (16ohm) Hi folks, this is my first post here. I'm a regular at Harmony-Central though. Anyway, I have a bit of a dilemma. Hopefully I won't seem too long-winded. I have a Marshall 1960A 4x12 cab, that is connected to my Engl Fireball 60watt valve amp. The Fireball has the capability of outputting to two 16 ohm cabs. I am currently in the process of modifying the cab so it is a "semi-Leslie" cab. Basically it will have two 'static' 12" speakers, and then either one or two treble drivers with rotating horns, for chorale effects. The 12" speakers are Electro Voice, 8ohms each. The treble driver/s are 16 ohms. I know that I can wire the EV speakers in series so that total impedance will be 16 ohms. And, I know I can have just one treble driver on its own, at 16 ohms, or have two drivers wired in parallel, so that total impedance will be 16 ohms. That way, all the impedances will be the same. But, how will I wire up the jackplate? As I said earlier, I can hook up two 16 ohm cabs, or "cabs" (ie two connections to 1 cab?) from the Fireball amp. I am a bit muddled, as you can see. Would it be best to just get another normal 1960A jackplate, set it to 16 ohms mono, and use that one to connect to the driver/s? And then use the other jackplate, set to 16 ohms mono, for the EV speakers? Or is there a more efficient way I can do this?