What's the most "universal" ohm rating in your opinion?



I just purchased a 2x10 ported pine cabinet (16ohm Celestion G10 Greenbacks) wired parallel for a 8ohm load. I did this even though I will be using it with a Marshall JTM45 Head (16ohms is said to be best) because I wanted a 8ohm cabinet for I thought I might be able to use it with a wider variety of amps (in the future) than I could with a cabinet rated for 16ohms (or 4ohms parallel).

So, what do you think? Most common ohm rating? Is there even a straight answer for this? Thanks.

I also wanted parallel wiring in case a speaker ever crapped out, so the amp would still see a load.



A player who collects
Gold Supporting Member
I don't think there is a straight answer, just opinions based on what amp types you prefer. I rationalize that many British style amps (Marshall, Hiwatt, Orange, etc) seem to prefer 16 ohms but most Fender head style amps (Tremolux, Bandmaster, Bassman, Dual Showman) are setup for 4 ohms. Consequently, all of my 2 speaker cabs are loaded with 8 ohm speakers and I have the jacks wired so I can run either 4 (parallel), 16 (series) or dual (stereo) 8 ohms. I do this either via a series conversion speaker cord or a jack plate setup like this:


Since my amp collection consists mostly of Blackface and Brownface Fenders and older style Marshalls, this works for me.


Most full sized classic Marshall 4x12 cabs are 16 ohms----- most Mesa 4x12 cabs are 8 ohms---- many full sized classic BF/SF Fender amps are designed to run into a 4 ohm load only (except Super Reverbs, 2 ohms, and Single Showman, 8 ohms).
There is no Universal Ohm Load that all manufacturers seem to agree on.
Switch your JTM45 to 8 ohms and plug it into your 8 ohm 2x12 cab----- and play the heck out of it.
No reason to overthink this................ gldtp99


I have never understood the worry about going // instead of series.
How often has that scenario happened.?
And...with That Logic.....what about all the thousands upon thousands of single speaker amps. Are Those Guys worried about their One Speaker going open and snapping their OT in half.? ;)


Most amps are capable of running at 8ohms, so I'd say that's probably the most "universal", strictly speaking...

Most Marshalls have 4/8/16 ohm switching.

Most Fenders don't really care about impedance.

Most Ampegs I've played have been switchable from 2/4/8 ohms.

To directly address your situation, set your Marshall to 8 ohms and forget about it. You won't notice a difference. If you got a 16 ohm cab, the difference you'd hear would be the speakers, not the amp.


While I have one cabinet wired in series, if a speaker fails open, there's no load on the amp...unless it is internal to the amp. That's a bad scenario and the player needs to understand that if the sound goes out, turn the amp off asap.

If there's a problem, it's with old Fender amps which mostly use 8 ohm speakers whether there are 1, 2, 4, or 6 of them. Seems like one of the BF era used a 4 ohm speaker, but I'm not sure which one. Champs probably.

Jeff Gehring

Gold Supporting Member
I think you're wasting your time asking that question here on TGP. You need to consult this guy...


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