Adding 16/4 ohms switch to 2x12 cab

delgwapo

Hi all

I've got a 16 ohms Orange PPC212OB cab fitted with two x Celestion V30s (8 ohms each) and I'm looking to add some sort of jack plate switch to enable easy switching between 16 ohms and 4 ohms configs. Came across this 'Plug and Play' Jack Plate which looks pretty good and would add the option of 8 ohms mono.

Has anyone used one of these before or does anyone know of a suitable equivalent that I could purchase from a UK seller?

Cheers

ICBM

Unless you want stereo (you can't get 8 ohms mono from two 8-ohm speakers), you're better to fit a simple "two hole" plate, a single jack and a heavy-duty DPDT switch.

Reason: the switching contacts in jacks are inherently unreliable, and if one goes bad you can end up with no load on the amp. I'm reasonably sure this is a factor in the number of blown output transformers in modern Marshall amps, since the standard 1960 4x12"s have such a switching panel, and I've found many with contact problems.

delgwapo

Looking at the wiring I think you can get 8 ohms mono (single speaker) using an open plug.

A bit of searching revealed that Marshall do a similar switching socket http://www.hotroxuk.com/marshall-dish-assembly-1960-a-b-300w.html but based on your comment, might be best to steer clear!

Not bothered about the 8 ohms option so perhaps a DPDT switch is the way to go. Thanks. 

ICBM

delgwapo said:

Looking at the wiring I think you can get 8 ohms mono (single speaker) using an open plug.

Yes - using a single speaker. But that won't work well in a closed cab, because the undriven speaker will then try to act as an out-of-phase passive radiator, and it will sound odd.

Definitely avoid the Marshall panel.

ecc83

ICBM said:

delgwapo said:

Looking at the wiring I think you can get 8 ohms mono (single speaker) using an open plug.

Yes - using a single speaker. But that won't work well in a closed cab, because the undriven speaker will then try to act as an out-of-phase passive radiator, and it will sound odd.

Definitely avoid the Marshall panel.

You COULD try a single speaker and a shorting plug in the "passenger"side? You might think a shorted jack is a dangerous device but accidentally shorting a valve amp is very unlikely to harm it. Careful with old transistor kit tho!

Dave.