Question/Help: Tube amp + Multiple Cabs

MartinBlythe

I'm not sure if this is possible and it's beyond my knowledge....

I have a tube amp (rehoused to a combo). It runs a Celestion Gold 8ohm currently. Prior to this I was using the Amp Head with a 2x12 cab (4ohms [2x8ohm speakers]). I like the idea of running the amp through the combo speaker and using the 2x12 as an extension. They are different Ohms however so I don't want to blow anything up.

Is there any kind of device that will let me either run both cabs together without changing the Ohm of the speakers or cabs...or....let me plug both in but only use one cab at once and when switched it will work with the correct output without me having to move cables at the back of the amp. The amp has 4, 8 an 16ohm output.

Apologies If I have over complicated this...I'm aware I'm being lazy and could just as easy swap a cable but that's much less fun than a new toy.

Thanks in advance for any advice

Martin

ICBM

You can run both cabs together with the amp set to 4 ohms. The total impedance of an 8 and 4 ohm cab together is 2.66 ohms, but (contrary to usual popular belief) this is a safe mismatch.

It’s not as easy to switch between the two cabs unless you want to run one of them mismatched, either 8 on the amp into the 4-ohm cab or vice versa - but both are usually safe, although it will change the tone a bit.

It also depends on whether you’re cranking the amp right up into power-stage overdrive - if you’re not, impedance matching isn’t that important at all.

ecc83

As IC says, size, the signal that is, is everything. With a big amp, 50W+ and fixed biased, running into a lower than optimim load COULD cause redplating and pop an HT fuse if you run the absolute *ts off the OP stage. In ordinary circumstances no bother.

If perchance anyone has a pokey amp WITHOUT HT fuses be especially careful of going ape'it.

BTW I made up a very simple switch box. Two 5A footswitches to give "either or" and both speakers. Must have done thousnads of cycles and with a variety of amp makes. Never bothered any of them.

Dave.

MartinBlythe

Thank you both very much for your advice...It's a 35w tube amp (Two Rock Studio Pro) but I run it at low volumes. I only had the idea as I have the 2x12 sat unused most the time. I will try running both and see how it sounds.

Martin