Tube Amps and non-matching ohms

[brewboy73]

Hi All,
First post. I have a question concerning running a speaker cabinet that does not match the same ohms as the amps output. I recently converted my Mesa Recto 212 over to stereo to run with my Mesa 2:50 power amp. Since the cab came with two 16 ohm speakers and I switched them out with 8 ohms, I ended up with extra speakers. I have a 5150 combo that I want to put the Celestions in. Problem is that the 5150's output is 16ohms. Now, I know that I do not want to run these 16 ohm speakers in parallel to get 8 ohms out of them, but if I run them in series to get 32 ohms, is that really going to create a problem? I've read over a couple of other boards that you never want to mis-match ohms with a tube amp, and others write that as long as the speaker load is greater than the output of the amp, than you are safe. Hoping to hear mulitple opinions. Thanks

 

[bandit2013]

You would be better with the 8ohm parallel combination than the 32. However, if you really like those speakers, perhaps you can change the output transformer. I looked of the Peavey 5150 and could only find infor on the head unit which has a load selector switch.

I know Mesa has info with their manuals on safe operating missmatch loads. May not apply to Peavey.

 

[Jackie]

What I've generally heard from techs and forumites alike is what you said - as long as the speaker load is bigger than what the amp needs to see, there shouldn't be an issue. Although I've never seen a 32ohm cab connected to 16ohms ever.

 

[soundchaser59]

As long as the mismatch is only one degree, it might be ok, depending on whether the amp is made to tolerate that.

Plugging a 16 ohm speaker into the 8 ohm jack on your amp is probably ok with most amps. That would be a one degree mismatch. Plugging a 24 or 323 ohm load into that same 8 ohm amp jack would be quite risky in my opinion.

the big risk is something the experts refer to as flyback voltage, which can damage the amp components. I say it's not worth it. You would be much better off just getting another set of speakers. Speakers are much easier to replace and much cheaper than amps and amp repairs.