Helios Mic Amp input impedance

strangeandbouncy · Dec 11, 2004

Hi All,

I have Helios Mic Pres with Beyer mini Mic transformers. I need to ascertain the input impedence. Does anyone know, or can anyone tell me how to find it out? Perhaps Beyer still make it. Fraid I don't have units here to tell you the part no.

many thanks

Andy P

NewYorkDave · Dec 11, 2004

Most mic pres made in the last 30 years or so are designed to be driven from a source impedance of 150-200 ohms, and have an input impedance of 1200 ohms or greater.

Mark Burnley · Dec 11, 2004

Beyer trannie 1:10 IIRC for use with 2128 amp.

Can't remember number off top of head I'm afraid!

Mark

Wonderlandaudio · Nov 15, 2006

Lustraphones 200:20K

pstamler · Nov 16, 2006

Drive the input from a signal generator; insert a resistor (say 600 ohms) in series with the input. The Helios should be on, but with phantom off! Measure the voltage on the generator side of the resistor (V1) and on the preamp side of the resistor (V2). Compute the voltage drop across the resistor (V1 - V2); divide that by the value of the resistor and you get the current being drawn (I). V2 / I = the preamp's input impedance.

Peace,
Paul

strangeandbouncy · Nov 16, 2006

Thank you Paul!

a veery belated but most greatfully recieved reply.

Cheers,

ANdyP

Helios Mic Amp input impedance

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Helios Mic Amp input impedance

Help Support GroupDIY Audio Forum:

strangeandbouncy

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