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Tips for woofers/mics/amplification and impedance
Tips for woofers/mics/amplification and impedance
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Old 18th November 2009, 02:50 PM   #1
freakout is offline freakout
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Join Date: Nov 2009
Default Tips for woofers/mics/amplification and impedance

Hallo everyone. I'm currently working on a couple of projects and i've
got several doubts regarding amplification and impedance. long story short:
i have a DYH-810 8'' woofer and i'm trying to understand what kind of amp should i connect, and that is where understanding impedance really comes into play. Since the woofer is 4OHM, i suppose i should connect an amp with an output impedance which is LOWER than that, am i correct? this statement comes because i used a small tube amp which i have, which has an output impedance of 51OHM and the efficiency of the woofer was *really* poor. also: i've got a number of contact mics(piezo discs) and for another project i have to use one as a mic and one in output, as a sortof speaker. so question is: what kind of amplification should i use for the "output contact mic" and for the "input contact mic", so to speak? should i always follow the low-to-high impedance combination? thanks in advance guys
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Old 18th November 2009, 04:48 PM   #2
thermal runaway is offline thermal runaway  United Kingdom
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Location: West Mids , UK
Regarding the speaker , as long as the spec of the amp states that the impedance range is from 4 ohms you won't have a problem. Valve amps are different , they have an output transformer and it's important the speaker connected matches the output impedance of the transformer. Some valve amp transformers have a number of impedance taps so that the speaker can be matched.

Can't help you with the mics , never did much with them.
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Old 20th November 2009, 12:09 AM   #3
PeteMcK is offline PeteMcK
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Join Date: Feb 2002
Location: Western Sydney
A piezo mic will need a high input impedance, of the order of 1 megohm.
some info on using them as out devices:
Lynn and Steve's Piezo page
Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 20th November 2009, 07:42 AM   #4
Enzo is offline Enzo  United States
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Location: Lansing, Michigan
A 51 ohm output? I have never seen that. Printed on it, or did you determine that somehow? Keep in mind resistance and impeance are not the same.
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Old 20th November 2009, 10:58 AM   #5
freakout is offline freakout
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Join Date: Nov 2009

go in "tech specs" and it shows it, assuming that i understand the thing correctly...i'm also using this tube pre for piezos, sometimes, and it doesnt work too bad.
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