SAFE MISMATCH?: Mesa TOV 2x12 combo(8) + Orange 2x12 cab(16)

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xiwiwix

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I'm going thru an old Mesa Dual + Triple Recto manual (paper) and in the back they have a picture showing/saying that it's ok to plug a 16 ohm cabint in to the back of the Mesa's 8 ohm speaker in, ***AND*** an other cab thats 8 ohms into the 4 ohm speaker in.

WHAT GIVES?!

Can I do this? I've been wanting to get another set of v30's for my orange cab so I could run both 2x12's with my Tremoverb.
 
Mesa has a higher impedance mismatch tolerance than other tube amps.
If they say it's safe, then it's safe.
I often run my Recto through both a 16 ohm cab and 8 ohm cab at the same time. Works fine and sounds great. No tone loss or volume difference.
 
you're going to get a lot of answers here. in theory (from the amp designers around here, and some of the engineers), some amps can't handle the flyback voltage, from what i've been told. some ppl will also tell you it's ok with solid state to be lower on the amp side than the speaker side....but not with tubes...to match up perfectly. i'd argue that most speakers are never the impedence thats rated on them anyway (which, by the way you CANNOT measure with a voltmeter or digital multimeter...you're trying to measure inductance in this case, not actual resistance)

others, like the mesa, actually will recommend you mismatching ohms....in this case,

16x8=128
128/(16+8)=5.33333333

setting the head on 4 ohms you should be fine. i wouldnt run it on 8 or 16 though, regardless of what mesa says.

quick answer, as long as your ohms of your cabs are greater (as in above equation) than the setting you have your head on, you SHOULD be find with most tube amps made today.

here's a pretty back and forth thread.

again, in short, head on 4, you'll be fine with a mesa.

viewtopic.php?f=3&t=93230&p=1100280&hilit=ohms#p1100280

viewtopic.php?f=3&t=104641&p=1230710&hilit=ohms#p1230710

viewtopic.php?f=3&t=108757&p=1276825&hilit=ohms#p1276825
 
Mesa Boogie themselves have said many times that you can mix and match impedance and that it will only affect tube life a little if anything. Mesa's are very well built amps and can withstand mismatches like you are asking about..
 
yeti":14ph9sjz said:
you're going to get a lot of answers here. in theory (from the amp designers around here, and some of the engineers), some amps can't handle the flyback voltage, from what i've been told. some ppl will also tell you it's ok with solid state to be lower on the amp side than the speaker side....but not with tubes...to match up perfectly. i'd argue that most speakers are never the impedence thats rated on them anyway (which, by the way you CANNOT measure with a voltmeter or digital multimeter...you're trying to measure inductance in this case, not actual resistance)

others, like the mesa, actually will recommend you mismatching ohms....in this case,

16x8=128
128/(16+8)=5.33333333

setting the head on 4 ohms you should be fine. i wouldnt run it on 8 or 16 though, regardless of what mesa says.

quick answer, as long as your ohms of your cabs are greater (as in above equation) than the setting you have your head on, you SHOULD be find with most tube amps made today.

here's a pretty back and forth thread.

again, in short, head on 4, you'll be fine with a mesa.

viewtopic.php?f=3&t=93230&p=1100280&hilit=ohms#p1100280

viewtopic.php?f=3&t=104641&p=1230710&hilit=ohms#p1230710

viewtopic.php?f=3&t=108757&p=1276825&hilit=ohms#p1276825
Click to expand...

^^^This

Pretty much everything else will fry your output transformer eventually.
 
I'd recommend anyone wondering "which way is ok to mismatch" a tube amp, to read this:

http://aga.rru.com/FAQs/technical.html#imp-1 (Read that and the point below it.)

There isn't such a simple answer as "use a higher impedance if in doubt", or that you can rely on Mesa amps to be safe when mismatched all the time. In the case presented in the original post, the mismatch isn't even a factor of 2 so it's fairly safe anyway. There will be an uneven power distribution to both cabs but it's not something you usually notice unless it's at a higher volume. But never presume it's ok to mismatch "higher but not lower" or something. As explained in that link I posted (which it seems no one ever reads), mismatching higher (than a reasonable amount) can be the one thing you seriously want to avoid.
 
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