Impedance Mismatch?

[schecterplayer]

I was recently given an 8ohm Marshall branded Celestion Vintage 30, which seems like the perfect speaker to replace the Celestion Seventy 80 that is currently in my Crate V1512. The problem is that the Crate only has one speaker output with an impedance of 16ohms. I have read that (for Tube amps) higher impedance can cause major problems but that going one step too low isn't generally a big deal. The manual for my Mesa Boogie actually says that mismatching one step in either direction is fine (although it certainly has much beefier transformers than the Crate). What say you guys? I won't be running the amp anywhere near full blast since I've got the boogie for higher-volume work.

[Archer_of_Fish]

Re: Impedance Mismatch?

My understanding is one up is OK down is not. Personally, I just dont mismatch.

[ericmeyer4]

Re: Impedance Mismatch?

Personally I wouldn't risk it. It was free see if you can't trade it for the one with the correct impedance.

You can also get the Weber Z-Matcher, but if your going to spend money might as well get the correct speaker.

[SlyFoxx]

Re: Impedance Mismatch?

Take it slowly volume wise and see how the amp reacts. I doubt it will be a problem as long as you're keeping below stage volume.

[FretFire]

Re: Impedance Mismatch?

I'd recommend matching if at all possible. Going up (16 ohm speaker/8 ohm amp) will sound dull and crappy, and going down can put extra strain on the amp and cause damage (4 ohm speaker/8 ohm amp)

[schecterplayer]

Re: Impedance Mismatch?

I'll look into trading speakers, this might be the motivation I need to swap this amps output transformer to a mercury magnetics, they have one for this model with 4,8, and 16 taps that costs about the same as a nice speaker.

[glassman]

Re: Impedance Mismatch?

Reach around to the back side of the chassis and see if there is one or two transformers back there; one on the right and another on the left. If you you find two, the amp will tolerate an 8 ohm load as long as you don't dime it and play for a long period. If it only has one transformer (the one on the same side as the input jack) then I wouldn't advise a mismatch; these amps have a transformerless power supply (similar to a computer) and can take a crap if the tubes draw too much current. Crate doesn't support these any more so once it dies, your only choice is to replace the power supply with a conventional transformer type.

[schecterplayer]

Re: Impedance Mismatch?

It's not one of the crappy newer ones. The V1512 was made in the Ampeg factory in the US and has a real power transformer. It's a great amp, I used it as my only amp gigging it once every couple weeks cranked to the max for years with zero problems. After it broke in really well I even started to like the Seventy 80, it's not the best but it's actually a pretty decent speaker.