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PilotAware - audio into King KMA 24

I can solder but the last amp I built involved valves:-)

EGNS, Other

You are either very trendy and into audio, or very old

(I used to build with valves too, in the 1960s… EF80, ECC83, EL84… apparently some of these are back in fashion, gold plated and made in Russia of course)

Administrator
Shoreham EGKA, United Kingdom

Very old..EL84’s….Ahh!

EGNS, Other

I had the same matching problem between a GMA 430 audio panel (which has an input impedance of 460 ohms)

I made an impedance matcher as documented by COPA and it works perfectly. I think it would achieve satisfactory results with a PilotAware and the KMA 24.

Here are the instructions / illustrations (although I put mine in a proper little case, rather than a pill-box!):



Last Edited by Pilot-H at 16 Oct 00:44

A 1k to 8 ohm transformer is a step down one, which will hugely reduce the signal, by about 11:1.

If it was wired backwards i.e. the 8 ohm side on the left in the above diagram, that would be roughly 1:11 gain (turns ratio is the square root of the impedance ratio i.e. sqrt(1000/8)) which should work.

Administrator
Shoreham EGKA, United Kingdom

Ah….Thanks, I’ll give it a try, just need mono so one transformer.
Had hoped something like that would work!
Funnily enough I bought a audio signal transformer on eBay last light, 500 ohm:16 ohm, both centre tapped so according to Peter’s formula(which I had long forgotten) using the centre tap on 16 I should get 8:1 and a few other possibilities. :-)

Last Edited by PeteD at 16 Oct 08:00
EGNS, Other

Peter wrote:

A 1k to 8 ohm transformer is a step down one, which will hugely reduce the signal, by about 11:1.

If it was wired backwards i.e. the 8 ohm side on the left in the above diagram, that would be roughly 1:11 gain (turns ratio is the square root of the impedance ratio i.e. sqrt(1000/8)) which should work.

Yes that’s how mine is wired, stepping UP. (and it works perfectly.)

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