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Author Topic: Best way to do a transfer function of an amplifier output?  (Read 1123 times)

Art Welter

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Re: Best way to do a transfer function of an amplifier output?
« Reply #10 on: October 23, 2018, 06:18:15 pm »

Next time I'll probably just get some oil-filled electric radiators and put a few in parallel.

Chris,

Since I already had them, used to do that, but it took 5 heaters to do a 2 ohm load, since those 1500 watt 120V heaters were about 9.6 ohms. Dragging 5 heaters to the shop was too much work, and could only test one side at two ohms.
Then I found that wrapping baling wire around a brick worked quite well, and is even cheaper than Mark W's solution, but does have some heat safety issues  ;)
IIRC, using a  8"x 3" x 2.25" brick and 16 gauge steel baling wire at about 1/4" spacing came out to 4 ohms.

Art
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Mark Wilkinson

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Re: Best way to do a transfer function of an amplifier output?
« Reply #11 on: October 23, 2018, 08:02:04 pm »


IIRC, using a  8"x 3" x 2.25" brick and 16 gauge steel baling wire at about 1/4" spacing came out to 4 ohms.

Art

 ;D

Did peeing on the bricks increase thermal capacity ? Lol
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Art Welter

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Re: Best way to do a transfer function of an amplifier output?
« Reply #12 on: October 24, 2018, 01:12:58 am »

;D

Did peeing on the bricks increase thermal capacity ? Lol
Yes, but changes the impedance too much for repeatable and reliable measurements.
Stinks like hell, too.
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Frank Koenig

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Re: Best way to do a transfer function of an amplifier output?
« Reply #13 on: October 24, 2018, 11:50:22 am »

I've mentioned this trick before but this sounds like a good place to mention it again. You can arrange the load resistor as a voltage divider so that you can hook a speaker to the tap and hear, at a pleasant level, what the amp sounds like when it's killing itself. Since the attenuation is high the source resistance seen by the speaker is low, and all is hunky-dory. -F







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