Tube amp impedance matching - Once and for all

[chille01]

I always try to just match the impedance exactly... but sometimes if you're sharing cabs at a gig, or at an hourly jam room, that isn't possible.  Or sometimes with an old vintage amp, you just don't know for sure what the output impedance is.

SO

I've read basically every type of opinion on this.  Safer to overload (4 ohm output into 8 ohm cab), safer to underload (8 ohm output on a 4 ohm cab)... everyone seems to agree that you shouldn't go more than 50% in either direction, but there seems to be much debate about whether it is better to overload or underload.  Is there a concensus here?

Specific heads that I deal with are a '73 Traynor YBA-1 (8 ohms, according to the interweb), and a 70's Silverface Bassman (4 ohms, or so I have been led to believe by the interweb)

Cheers in advance.

[Hemisaurus]

already covered, in the tech thread

[LogicalFrank]

For tube amps, the impedance on the cab should be lower than what the amp is set for if you are going to mismatch. Keep it w/in a 2:1 ratio either way and you're generally OK, esp. if you are not cranking it. Some amps take mismatches better than others so be careful and don't do it unless necessary.

For solid state, the opposite is true. Solid state amps will overheat w/ too low a load. You can put too high a load on them all day though and all you'll lose is volume.

I think a lot of the confusion comes from people applying what the learned installing their car stereos to tube amps.

[RacerX]

"Once and for all," my ass. 

[VOLVO)))]

Don't mismatch. My .02$.

[Hemisaurus]

Don't mismatch. My .02$.

The prizewinner. Unless you have a signed affidavit from the manufacturer that it's OK, or the money in your pocketbook to replace an output transformer.

[VOLVO)))]

Don't mismatch. My .02$.

The prizewinner. Unless you have a signed affidavit from the manufacturer that it's OK, or the money in your pocketbook to replace an output transformer.

congrats on 1000+posts, loser, how was vacation?

[justinhedrick]

nice. 1000+ posts. where did you vacation to? you live in illinois, why leave?! 

[Hemisaurus]

nice. 1000+ posts. where did you vacation to? you live in illinois, why leave?! 

Don't get me started man, I could have been in Wisconsin, at least they have some hills there, and know how to drive in the snow. All things being equal, if I have to live in the US, I quite like the WV and Carolina's, probably NC in the hills, or over in WA or OR. Also the density of musicians with taste is better.

[justinhedrick]

nice. 1000+ posts. where did you vacation to? you live in illinois, why leave?! 

Don't get me started man, I could have been in Wisconsin, at least they have some hills there, and know how to drive in the snow. All things being equal, if I have to live in the US, I quite like the WV and Carolina's, probably NC in the hills, or over in WA or OR. Also the density of musicians with taste is better.

no shit.

[chille01]

Thanks all. Believe it or not, I did run a search before I started this thread. Of course, the only thing it turned up was a previous post of mine, where it turns out I also spelled impedance wrong. I guess I should put spell check in front of the search box in my signal chain.

Cheers!

[VOLVO)))]

Thanks all. Believe it or not, I did run a search before I started this thread. Of course, the only thing it turned up was a previous post of mine, where it turns out I also spelled impedance wrong. I guess I should put spell check in front of the search box in my signal chain.

Cheers!

[chille01]

Spelled and spelt are both valid actually. I think one is UK English, and the other is American. Not sure which is which. I also spell color as colour. Same deal there.

But impedance has an a in it, and there is indeed all of the answers I need in the tech thread.

Gracias.

[VOLVO)))]

The fuck? I could have sworn it said "speeled." I may have had mod-mind lapse and modified it. I correct all of you'se guys grammar and spelling! Bahahahaha

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