Magical World of Ohms
- Thread starter Conroyfootball
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Pink Unicorn Horsey
Megä Pöny Rÿdr
Re: Magical World of Ohms
:chairfall
I can calculate equivalent parallel and series impedances, but I can't read minds...at least not on Tuesdays.
:chairfall
I can calculate equivalent parallel and series impedances, but I can't read minds...at least not on Tuesdays.
Danglin' Fury
New member
Re: Magical World of Ohms
I just read in electronics class about fiber optic circuits. It says the greater the impedence, the greater the sacrifice to bandwidth. I will do some studying to find out if this pertains to audio also as I am curious now.:dot:
I just read in electronics class about fiber optic circuits. It says the greater the impedence, the greater the sacrifice to bandwidth. I will do some studying to find out if this pertains to audio also as I am curious now.:dot:
Rich_S
HomeGrownToneBrewologist
Re: Magical World of Ohms
Eric and KG, I stand by my answer. With tube amps, it's better for the load to lower than higher. (Although either of the examples given, 4- or 16-ohm speaker on an 8-ohm output is unlikely to cause problems.)
Don't believe me? Try this experiment: run one vintage Marshall with its output shorted. Run a second amp with the infuriatingly unreliable impedance-selector thingie removed, effectively opening the OT secondary. Blast "Smoke on the Water" through both amps. What happens? For the shorted output, chances are not much. For the open secondary, there will likely be smoke & flames coming from the OT and other components in the output stage.
There are many quality tube amps out there that actually have a shorting jack for the speaker outputs, because a short is better for the amp than running it open-circuited if you forget to plug in the speaker cable:
the blackface Super Reverb for example, or the Ampeg V4, or even the Dumble Overdrive Special. Of course this won't help if you plug the cable into the amp, but not into the cabinet.
Solid-state amps are exactly the opposite - they will run all day into an open circuit, but don't like impedances lower than rated, down to and including short circuits. Quality hi-fi and pro audio amps have protective circuits to shut the amp down in these overload cases, so a short won't kill them, but the amp won't work into the low impedance, either.
To answer the original question, there are some tonal differences both from mismatched impedances and from differing matched impedances in otherwise identical amp/speaker combinations (think Bandmaster vs. Super Reverb). Gerald Weber did a good job covering this in his latest book.
Eric and KG, I stand by my answer. With tube amps, it's better for the load to lower than higher. (Although either of the examples given, 4- or 16-ohm speaker on an 8-ohm output is unlikely to cause problems.)
Don't believe me? Try this experiment: run one vintage Marshall with its output shorted. Run a second amp with the infuriatingly unreliable impedance-selector thingie removed, effectively opening the OT secondary. Blast "Smoke on the Water" through both amps. What happens? For the shorted output, chances are not much. For the open secondary, there will likely be smoke & flames coming from the OT and other components in the output stage.
There are many quality tube amps out there that actually have a shorting jack for the speaker outputs, because a short is better for the amp than running it open-circuited if you forget to plug in the speaker cable:
the blackface Super Reverb for example, or the Ampeg V4, or even the Dumble Overdrive Special. Of course this won't help if you plug the cable into the amp, but not into the cabinet.
Solid-state amps are exactly the opposite - they will run all day into an open circuit, but don't like impedances lower than rated, down to and including short circuits. Quality hi-fi and pro audio amps have protective circuits to shut the amp down in these overload cases, so a short won't kill them, but the amp won't work into the low impedance, either.
To answer the original question, there are some tonal differences both from mismatched impedances and from differing matched impedances in otherwise identical amp/speaker combinations (think Bandmaster vs. Super Reverb). Gerald Weber did a good job covering this in his latest book.
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ErikH
Well-known member
Re: Magical World of Ohms
Damn, this stuff can be confusing. I was always told never to go lower.
Here's something that backs up Rich.
http://www.geofex.com/tubeampfaq/TUBEFAQ.htm#matchspkr
Considering R.G. Keen's credentials, I think we're trumped...LOL.
Damn, this stuff can be confusing. I was always told never to go lower.
Here's something that backs up Rich.
http://www.geofex.com/tubeampfaq/TUBEFAQ.htm#matchspkr
Considering R.G. Keen's credentials, I think we're trumped...LOL.
guitarded
New member
Re: Magical World of Ohms
Hmmm.... I guess it makes sense. I still think the best thing to do is keep the load matched up with the amp.
Rich S. : I guess an apology is in order
Hmmm.... I guess it makes sense. I still think the best thing to do is keep the load matched up with the amp.
Rich S. : I guess an apology is in order
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