Pro Audio Design Forum

Now available for download, a new eBook from the Electronic Design Library: Bob Pease on Analog.

The link requires name and email registration but the pdf is worth having in your library...

http://electronicdesign.com/Electronic_ ... ok1_Vol._1

I may make something like this from Paul Kemble's site: https://proaudiodesignforum.com/images/jpg/E-Line_Transistor_Thermal_Clip_Gembias.jpg Feranti E-line thermal coupling from the Practical Electronics Gemini This is what Paul suggested. These are the same "e-line" transistors as the ZT...

Dr. James R. “Bob” Biard (born May 20, 1931) is an American electrical engineer and inventor who holds 72 U.S. patents, including the GaAs infrared light-emitting diode (LED), the optical isolator, the Schottky transistor, and Metal Oxide Semiconductor Read Only Memory (MOS ROM). He has been on the...

I found these interesting level meters and tools from Darkwood Designs Applause meter ... or 'Clap-o-meter' Wide Range Peak Meter with Phase Correlation Multi-Channel Level Meters - ‘Analogue’ and Bargraph styles 'Analogue' BBC-style Peak Programme Meters ME/12 Mini-PPM Twin PPM Quad PPM Peak Progra...

Two small plates on either side of the transistors with holes for screws at the outer edge. Then tighten the screws and nuts to squeeze the plates together.

That's a good idea.

I think winding thin wire around them like wire wrap wire would work and be reversible. Just gave me the idea of stuffing them into the coil of a slightly undersized shorth length of spring. Like an Accutronics reverb spring. Was also wondering about using adhesive copper foil or even an aluminum f...

Thanks John. I need to find a simple way to thermally-bond the two transistors. Right now they are heatshrunk together. Works OK and the DC drift is manageable but air currents create swings with periods in the tens of seconds. The output servo deals with that drift but it could be less. The actual ...

I did some additional measurements with 56 dB gain and with the hum field nulled. Rsource is 3R3 Rgain 1R 2X ZTX851 and NJM2068. The OPA1612 performs identically to the NJM2068DD. Ein of -143 dBu. Voltage noise density 0.367 nV/√Hz Env = 8.3 Ohms https://proaudiodesignforum.com/images/jpg/Flat_Movi...

Some noise measurements of the ZTX851-based Balanced Input Moving Coil Preamp. https://proaudiodesignforum.com/images/jpg/Flat_Moving_Coil_Preamp_ZTX851_NJM2068_Gain_50dB_Rsource_3R3.jpg Balanced Input Flat Moving Coil Preamp Using the ZTX851 and NJM2068DD. Output noise FFT, Gain 50dB Rsource 3R3. ...

Would using a 1246 (+6dB) allow you to drop the resistances even lower...? Good eye. I've thought about that and this is one of those cases where it might. Though it intuitively seems wasteful to throw away gain in a preamp, the NF is about 2 dB better when its running at 56 dB in the INA vs 50 dB ...