Ohm question

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ok...what the tone difference between running my head 8 ohm into 8 ohm cab, and running my 8 ohm head into 16 ohm cab?
 
Your amp won't like the last one very much. Always match the amp output und cab input!
 
Not true. It's called a "safe mismatch" and his amp won't care a bit. The sound will be a little "less" (for lack of a better word), but some people like that.
 
scottph":2lv26vpg said:
Not true. It's called a "safe mismatch" and his amp won't care a bit. The sound will be a little "less" (for lack of a better word), but some people like that.
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This kind of safe mismatch fits for transistor amps only. With tube amps the output transformer will have higher voltage and so the risk of damage increases (in extreme running with no load at all, meaning no cab plugged in). So in general the impedance of the cab should be the same or lower than the setting on the amp (for tube amps).
 
Still I wouldn't do and recommend it. There no benefit you will get from doing it and not every amp is built as strong as a Diezel. Though it is a "safe mismatch" there is a reason why there is a output for each impedance :)
 
It sounds different when you mismatch "up" (you could also mismatch "down") - always just one "step".
Different in this case equals "smoother", esp. the neg feedback (presence) frequ. will shift a bit (ever used an old Marshall set to 4 Ohms into a 16 Ohm cab? - not recommended, but thats a smooth Marshall sound).

Decades ago Boogie suggested to try around with mismatching your combo and its 8 Ohm speaker using the 4 Ohm out. Wasn't my cup of tea though - I prefer it the other way round (sometimes).
 
oeatschie":1y4slsmh said:
scottph":1y4slsmh said:
Not true. It's called a "safe mismatch" and his amp won't care a bit. The sound will be a little "less" (for lack of a better word), but some people like that.
Click to expand...

With tube amps the output transformer will have higher voltage and so the risk of damage increases (in extreme running with no load at all, meaning no cab plugged in). So in general the impedance of the cab should be the same or lower than the setting on the amp (for tube amps).
Click to expand...

This is true if we were to talk about 8 ohms on the amp and 4 ohms on the cab (unsafe mismatch), but not with a 16 ohm cab and an 8 ohm amp.
 
One step in either direction is ok . . .


. . . and for bedroom rockers even more than just one :D
 
scottph":2qj7g6qs said:
oeatschie":2qj7g6qs said:
scottph":2qj7g6qs said:
Not true. It's called a "safe mismatch" and his amp won't care a bit. The sound will be a little "less" (for lack of a better word), but some people like that.
Click to expand...

With tube amps the output transformer will have higher voltage and so the risk of damage increases (in extreme running with no load at all, meaning no cab plugged in). So in general the impedance of the cab should be the same or lower than the setting on the amp (for tube amps).
Click to expand...

This is true if we were to talk about 8 ohms on the amp and 4 ohms on the cab (unsafe mismatch), but not with a 16 ohm cab and an 8 ohm amp.
Click to expand...

Your assumption is correct for transistor amps. For tube amps it's the other way round.
 
No.

Tube amp @ 4 ohms -> cab @ 4, 8 16 ohms is ok.
Tube amp @ 8 ohms -> cab @ 8, 16 ohms is ok.

That's all there is to it. Going down is an option for bedroom playing, like Olaf said, but it's unusual. Going up in impedance can not harm your amp or your cab - the tone will change, nothing else.
 
scottph":vodoeztr said:
No.

Tube amp @ 4 ohms -> cab @ 4, 8 16 ohms is ok.
Tube amp @ 8 ohms -> cab @ 8, 16 ohms is ok.

That's all there is to it. Going down is an option for bedroom playing, like Olaf said, but it's unusual. Going up in impedance can not harm your amp or your cab - the tone will change, nothing else.
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OK, so lets listen to Mr. Soldano:

"If the load is lower than what the amp is set for, like using a 4 ohm cabinet with the amp set at 16 ohms, the power tubes will be worked harder and will run hotter. This, of course, will shorten the life of the power tubes. However, if the load is higher than the amp's setting, like using a 16 ohm cabinet with the amp set at 4 ohms, the voltages in the output transformer will be higher than normal. These excessively higher voltages increase the risk of arcing, which can destroy the output transformer and/or tube sockets. That's why running an amp with no load at all invariably ends up blowing the output transformer."
 
Ok. I doubt arcing is a problem in this day and age with the parts being used in Diezels. Also, most of us don't play anywhere near the volume it would take to really drive the cab, but oh well...
 
Its vice versa Scott.

Most of us do use these kind of volumes ;)
 
oeatschie":kqih02vm said:
scottph":kqih02vm said:
Also, most of us don't play anywhere near the volume it would take to really drive the cab, but oh well...
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I do :rock:
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so do i! :rock:

and it always makes me jump up and down for joy, because every time i crank the amp up i have this "oooooooooohhhh yeeeeeaaah, thats what its made for!"-feeling, and i love it.
 
duesentrieb":22zvv1fr said:
Its vice versa Scott.

Most of us do use these kind of volumes ;)
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No problem, but my point still stands: You can savely use higher ohms on the cab than on the amp, right?
 
Yeah Scott thats what I always thought. :confused: It's safe to run a TUBE amp at like 4ohm and run it into a cab @ 8ohms. I don't see why it would be diffrent for a transistor amp either. I am no expert though. Maybe I was misinformed? I have never mismatched a head with cab. I owned a 5150 and ran it 4ohm to 4ohm but other than that it's always been 8 ohm to 8 ohm.

Besides, I think Mr. Soldano does things diffrent with his amps. I own a soldano SLO and the factory says that biasing isn't nesessary unless you change tube types. I always bias the tubes on my VH4.
 
Same here man. I had my 6505 and my Powerball hooked up in a safe mismatch config, and it sounded good to me. Tried it with the Herbert too, and I did like it for some stuff, not so much for other stuff. Anyhow, I never had a problem with it, and I ran the PB like that for quite a few months...but oh well...
 
what about using two different ohmed (stupid word i know ;) ) cabs on one amp is that possible? i know that when using two 16 ohm cabs u have to connect them with the 2 8 ohm outs of the diezel. but what about if you have a 16 and a 8 ohm box, is it possible to connect them both without mismatching them?
 
I'm thinking that cabs are in series, so Ohms law would be: 16*8/16+8= 5,333333 Ohms -> use the 8 Ohms out. Somebody correct me if I'm wrong... :confused:
 
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