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Topic: speaker impedance |
Ray DeVoe
From:
Hudson, FL
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Posted 17 Feb 2005 4:34 am |
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A question for one or more of the electonic wizs out there. And there seem to be quite a few very knowledgeable people on the forum.
Brad Sarno's in depth explanation of amp frequency roll off points left more than a few of lesser geeks saying "gee whiz."
I'm sure that many players out here appreciate the help and willingness to share, which is demonstrated on here by so many experienced and dedicated players and electronic people. It's a unique community.
When running my Webb or any amp that is rated at 2 ohms out, does it hurt to run this configuration.
In this case, a 4 OHM JBL E 130 in the amp cabinet and a 8 ohm JBL K 130 in an extension cabinet. Its currently what I have for a speaker to install in the extension cabinet. It sounds great at house levels.
I shortly will have one 4 ohm D 130 F that I can install after Woody finishes the recone work.
I beleive from what little I know about electronics that an 8 and 4 ohm load when added together and calculated out with the resistance formula adds up to some weird load of 2.6 total load ohms, or something like that.
I am getting old enough that I cant remember my high school days or what was taught in it. LOL.
Thanks in advance for any replies.
Ray DeVoe |
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Jack Stoner
From:
Kansas City, MO
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Posted 17 Feb 2005 6:14 am
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You are correct on your calculation.
The amp's "2 ohms" is the MINIMUM you should have.
Maximum power and frequency response occur when the load (in this case speakers) is equal to the output impedence of the amplifier. This is more noticeable on units that have an output transformer than it is with a "tranformerless" output.
How much power and/or frequency loss is debateable and with some amps it will never be detected or the power amp has enough power to be adjusted for desired output.
There are other amps that have difference specs or suggestions. I have a MosValve 500 power amp. On the back it has "use 8 ohms for best performance". However, the Genz-Benz tech told me "do not go below 4 ohms". I'm using 8 ohm BW 1203-8 speakers and have more than enough power and excellent frequency response. I've heard others, such as Herby Wallace that uses Peavey Nashville 115E speakers, with the 4 ohm speakers and it sounds just as good. |
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Roger Kelly
From:
Bristol,Tennessee
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Posted 17 Feb 2005 6:15 am
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| Ray, your math is correct. You shouldn't have any problem with your Webb. |
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