Pro Audio Design Forum

"LED used as voltage reference provides self-compensating temp coefficient," Peter Lefferts, Electronic Design, February 15, 1975. https://www.ka-electronics.com/images/jpg/LED_Voltage_Reference_IFD_1975_small.JPG LED used as voltage reference provides self-compensating temp coefficient,&...

"A Super Simple Three-Mode Simultaneous Input, Variable Resonance, Voltage Controlled Filter For Signal Processing." Nyle A. Steiner, 1970's. https://www.ka-electronics.com/images/pdf/Steiner_Filter.pdf Never built one of these. This paper was shown to have been received at MicMix sometime...

CBS SQ Quadraphonic Decoder documentation from 1974 using the Motorola MC1312, MC1314 and MC1315 ICs. Variable Blend SQ Full-Logic Decoder, L-2 Using Motorala Integrated Circuits, March 4, 1974. (Full pdf, 11 pages, 506 KB) Also included in the pdf are the instructions for the Motorla HEP C6126, C61...

Might be a useful circuit. At least I thought so in 1975 when I saved it.

Note the Jim WIlliams 1974 citation in reference 1.

I found this 1982 EDN article written by Andy Rappaport. Ready for Digital Audio? It might arrive sooner than you think. By the end of this year, you might be buying hour-long stereo records that fit in your pocket. https://www.ka-electronics.com/images/pdf/EDN_Digital_Audio_1982.pdf (4 MB) In addit...

Send us a pic?

The TI app for the PGA2500 IIRC showed whimpy protection diodes to the rails which do become leaky (if not shorted or ohmic) after faults. MOTU may have followed the app right out of the book.

I didn't see those kind of changes with a dummy cart. Floating was still an improvement over SE but maybe 4-6 dB (hum) eyeballing the graphs.

Both graphs are a 200 sample average and it looks like it's external hum with high harmonic content that's producing the big changes with open inputs.

I decided to post a couple of more snapshots before I tear down the protoboard and build this. I want to use this design because you can run the front end floating. https://www.ka-electronics.com/images/jpg/P10_Input_Connections.jpg Comparison of P10 Differential vs. Single-ended Input Connections h...

This was something that really concerned me in Jurassic times. There's no problem with Shure, ADC, Ortofon, Goldring and Grado, at least I couldn't measure any difference in distortion, tracking etc. on Test Records. What the high Ib does allow is a small, well defined offset to bias a nice Panason...

Well, for a single-channel flat preamp with differential input I'm counting 10 resistors, 7 capacitors, a THAT1240, a TL072 and a dual 2SK389 FET selling for about $15. :geek: (But I have the FETS.) I don't think it can get any simpler. I suppose I could crank up the current but I may want to run th...