Pro Audio Design Forum

The stars must be aligned. I want to use this design because you can run the front end floating. Thanks for posting Paul. It's an easy build. WRT floating: How does that work in practice regarding wiring past the tone-arm base? Do you have to re-wire from the arm base using shielded twisted pair to...

Yeah, it appeared to be in common mode at the drain loads and I'm not seeing any issues with noise through that node. I think the P10 drawing had an arrow going to "C15." Didn't know how elaborately filtered C15 might have been. Sounds like C15 was big. With a 2SK389V (the loose grade) and...

Hmm...Did those two-transistor preamps in cheaper gear crap out under that challenge? It's brutal listening to the un-EQ'd playback due to the HF energy. That's the same stuff the front-end hears. I think I'll add a RIAA EQ stage for a monitoring side-chain. It would be handy to have the RIAA EQ swi...

In this thread JR provided us copies of his P10 and P100 phono preamps. In the thread I mention that I'm interested in building a flat preamp, without RIAA equalization, to experiment with declicking prior to RIAA equalization in software. Update 9/5/2015: The final construction information, includ...

I had several customers use my old P-10 this way. As I understood it, de-clicking before the RIAA playback EQ meant you were dealing with shorter events. Running the brief click transient through the LPF of RIAA, spreads out the energy in time, making it harder to remove, and involves punching a la...

the slew rate seems a little weak for use in audio path.. OK, let's clarify for our readers and for the sake of discussion that the servo itself is not directly in the audio path. Let's also stipulate for sake of discussion that the servo topology we're about to discuss is a typical simple invertin...

From what I can see, it's likely to be something simple like leaky P48V caps or protection diodes. Does it do it with phantom off? The P48V caps would be a good place to look. Did they use 1N4148 (in SMT) protection diodes? That would also be a good condidate. Depending on where they placed the dio...

January 10, 2012. This thread began life as a history of variable gain differential amplifiers and discussed the origins of the SuperBal input. Since it later expanded to a general discussion of balanced inputs I decided to re-name it. Thought some of you might find these examples of variable gain ...

Jensen Twin Servo 1997 Version

The AD706 has a SR of 0.15 V/uS. There is no passive LPF at the servo input nor is there a passive LPF at the servo output.

Not to quibble but there is no (RxC) LPF on that input, while there is a transformer in series that is in fact a BPF. We can observe he did the servo right with real pole on it's input. https://www.ka-electronics.com/images/jpg/Servo_Close_Up.jpg Yes, there is. I was talking about the servo input ,...