Pro Audio Design Forum

Could the MPSA92 be selected for low noise? They're common and in production.

Those look to be discontinued Sanyo. I keep seeing more openings for Central Semi and Linear Systems. These HV/LN parts - and discretes in general - are going EOL fast.

My original thought that led to this was that high voltage capability and low noise in the input transistors were almost mutually exclusive. Flying the rails around allowed less critical HV parts to be used. Hopefully someone will pickup production of the 2SA1084 and 2SA1085 like Central, Linear Sys...

Well, there may be a problem using those: http://documentation.renesas.com/eng/products/transistor/rej03g0635_2sa1084ds.pdf I was afraid of that when I noticed your link was to datasheet archive and the datasheet was 2001. So many parts are getting killed off. Maybe ON or Fairchild will pickup the 2...

Customers would probably be more turned off by the switch noise, than any subtle sonic benefit they might receive. Customers are funny that way. The best sounding audio path will be dismissed if it suffers switch clicks and pops and turn on/off transients, as evidenced by all the cap coupled gain p...

Thank you Rob for the kind words and history. You may have inspired me to dust off that protoboard and for that matter my entire workbench. I haven't done much in there other than change batteries since November. As I mentioned to Ilya earlier up in the thread I would change the servo to the one her...

https://www.ka-electronics.com/Images/p ... ook_V4.pdf (25 MB)

I used cross-coupled diff amps in figure 10 of DN-140 because they were symetrical:

http://www.thatcorp.com/datashts/dn140.pdf#page=14

Why inverting buffers?

The one thing I do like about the circuit in figure 6-26 is the ease of gain adjustment via R5. Adding passive LPF to both input resistors, protects the opamps from slew limiting, and reduces the HF CM energy making rejection easier. I agree, but what topology network would you use? A cap to ground ...

I highly recommend this. It's only about $38 in paperback.

Op Amp Applications Handbook (Analog Devices Series) http://www.amazon.com/gp/product/075067 ... ss_product

Wayne