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Impedence problem
#3031032 02/29/20 07:59 PM
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I bought a boogie on Ebay, and it has problems. It had a very ice-picky treble sound, so I got a used EVM speaker to tame it. It sorta helped, but it still didn't work right.

Well, I got my tax refund, and the amp is now off in California, getting worked over by Mike Bendinelli, Boogie man Extraordinaire, and apparently, it needs it bad. Somebody had it worked on by a total idiot, who replaced some of pots with others of wrong values, put piles of hot glue in it to hold components in place, and just generally jacked that sucker up big. It is being rebuilt in a major way, and I can't wait to get it back.

In the meantime, I still have the EVM. I will be going back to the Celestion Black Shadow, because I liked it better on my first Boogie. I thought I would get a 1x12 cabinet for the EVM and balance the tone with a brighter and darker sounding speaker in combination. But, the EVM is 4 ohm and the Celestion is 8. The amp only has 8 and 4 ohm outputs. How can I run the two speakers together?


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Re: Impedence problem
picker #3031033 02/29/20 08:22 PM
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You should be able to hook them both up, plug them both into the 4 ohm outlets.
Call Mesa and ask them, they are very helpful.

FWIW, I've owned a MK III, Studio .22, Maverick, Blue Angel, DC5, 2 Subway Blues, a Subway Rocket and an Express 5:25.
I bought the MK III new, had problems with it that replacing the tubes did not solve and went to the Mesa factory.
Mike Benadelli inviited me to come back and he showed me where he found a cold solder joint and performed "the hammer test" right in front of me. It was not gently and the amp passed. Never had another problem with it until one gig it blew V1 on the first not and I had to play through the other band's GK guitar amp - which sucked.

I'm not gigging tube amps any more and they are all long gone but I got some great tones out of my Mesas. If anybody can fix it, Mike B's got ya!!!!


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Re: Impedence problem
picker #3031896 03/06/20 04:30 AM
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Your 2 options for speaker connections are either series or parallel. Im series they would be 12 ohm. In parallel they would be 2-2/3 ohm. Even on the 4 ohm tap I can't possibly imagine running such a low impedance would be a good thing and I would think could even cause damage. 12 ohm in the 8 ohm tap is also not ideal but I would think at least would be safe - probably just lower output and maybe not ideal tone. You're probably better off just picking one of the two and connecting appropriately. As an alternative, you could use so,etching like a 4 ohm power break in series with the 4 ohm speaker, both in parallel with the 8 ohm speaker which would give 4 ohm overall. But that would make the 4 ohm speaker significantly lower volume than the 8 ohm.


Dan

Acoustic/Electric stringed instruments ranging from 4 to 230 strings, hammered, picked, fingered, slapped, and plucked. Analog and Digital Electronic instruments, reeds, and throat/mouth.
Re: Impedence problem
picker #3031968 03/06/20 04:53 PM
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I would wait until you get the amp back from Mike B. The amp could have been the problem with the ice-picky-treble sound as opposed to the EVM speaker. I would go with the 8 ohm Celestion Black Shadow speaker that you really liked the sound of as opposed to running two mismatched speakers. You can always ask Mike B what he thinks...good luck with it! cool


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Re: Impedence problem
picker #3031972 03/06/20 05:24 PM
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Originally Posted by picker
Well, I got my tax refund, and the amp is now off in California, getting worked over by Mike Bendinelli, Boogie man Extraordinaire,

I know Mike Bendinelli fairly well, I used to go to Petaluma to have my Boogie amps gone over by him. In fact I sold him some PA gear that I had in storage in Reno Nv. when I was living there.


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Re: Impedence problem
Larryz #3031974 03/06/20 05:28 PM
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Originally Posted by Larryz
I would wait until you get the amp back from Mike B. The amp could have been the problem with the ice-picky-treble sound as opposed to the EVM speaker. I would go with the 8 ohm Celestion Black Shadow speaker that you really liked the sound of as opposed to running two mismatched speakers. You can always ask Mike B what he thinks...good luck with it! cool


Yes, on a boogered Boogie all bets are off.
One of the 9 Mesas I owned was tragically boogered and eventually just sh*t the bed and died.
Was too expensive to fix - a Subway Rocket - no reverb. I flipped the head as-is - as described on ebay and got a few bucks for it.
Still have the cabinet, a good 1-10" for all those places that don't need loud.

Speakers on a tube amp are connected to the secondary coil of an output transformer. A short or open will cause damage, impedence mismatches can change the tone and available output, may shorten the life of the output tubes. J Dead is correct that a higher impedence is probably safer.

Most of the time you will only need a single 12" to make the Marshall half stack kids run away crying so consider trying both speakers and choosing your favorite. I used an EV in my Mk III Simul-Class (rev + eq). It had a bigger sound with more convincing bottom end than the Black Shadow. A Peavey Scorpion Plus sounded great in there too.


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Re: Impedence problem
picker #3032678 03/11/20 01:31 AM
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Anybody got an 8ohm EVM 12 they'd trade for a 4 ohm EVM 12?


Always remember that you�re unique. Just like everyone else.




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