Search found 263 matches

by ricardo
Mon Oct 12, 2015 1:44 am
Forum: Pro Audio Design
Topic: New: A Direct-Coupled Input-Capacitorless Active Mic Preamp
Replies: 122
Views: 248750

Re: New: A Direct-Coupled Input-Capacitorless Active Mic Pre

It appears that as Rs increases Q drops or, Q rises as Rs drops. To achieve critical damping it looks like the servo response tau needs to be at least 0.5 seconds maybe a little longer. Its easily do-able by changing Cservo, Servo Rfb or Rinject. I think a spreadsheet will make sorting it out a lit...
by ricardo
Thu Oct 08, 2015 11:36 pm
Forum: Pro Audio Design
Topic: New: A Direct-Coupled Input-Capacitorless Active Mic Preamp
Replies: 122
Views: 248750

Re: New: A Direct-Coupled Input-Capacitorless Active Mic Pre

After dismissing Wayne's design as far too complicated for dis beach bum's KISS philosophy ... I'm looking with a very jaundiced eye at my (actually Professore Angelo Farina's) MOTU Traveler Mk2 which is showing leaky P48V caps after 7 yrs. It's galling as I have a 1970's Calrec P48V PSU which is st...
by ricardo
Tue Sep 29, 2015 2:42 pm
Forum: Pro Audio Design
Topic: Flat Phono Preamp Based on John's P10 and 2SK389
Replies: 248
Views: 328385

Re: Comparing the NJM2068 to the OPA2134 in the Flat Preamp

I later found that the OPA2134 is actually better with a cart, compared to a resistor, due to its lower current noise. In the midrange the NJM2068, NJM2114 or NE5532 out-perform the OPA2134 where it's higher voltage noise dominates. Got some numbers or preferably some noise spectrum plots for this?...
by ricardo
Mon Sep 21, 2015 4:59 am
Forum: Build
Topic: Phono Transfer System Construction Information
Replies: 227
Views: 258552

Re: Phono Transfer System

This is the construction thread for the Flat Phono Preamp and RIAA EQ/Monitor Switcher that evolved from the discussion here: http://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=6&t=423 This is great stuff Wayne. Electronics for the ultimate vinyl system :ugeek: The ATR-96 MM cartridge is ...
by ricardo
Fri Sep 11, 2015 6:14 pm
Forum: Pro Audio Design
Topic: Flat Phono Preamp Based on John's P10 and 2SK389
Replies: 248
Views: 328385

Re: Flat Phono Preamp Based on John's P10 and 2SK389

My article in Linear Audio Vol. 10 is out. I cover IIR and min phase FIR using a trick that I have not seen elsewhere. The IIR coefficients are tablated there for <.005dB accurate response even at 48K sampling for RIAA and most of the historical equalizations. I only posted the FIR's for RIAA but s...
by ricardo
Sat Sep 05, 2015 8:19 pm
Forum: Pro Audio Design
Topic: Flat Phono Preamp Based on John's P10 and 2SK389
Replies: 248
Views: 328385

Re: Flat Phono Preamp Based on John's P10 and 2SK389

mediatechnology wrote:What is SME?
HA! That dates you as a young whippersnapper who wasn't around in the Golden Age of Vinyl. :mrgreen: SME 3009 series II. Touted as the 'best pickup arm in the world' .. as were all previous & subsequent versions.

Image
by ricardo
Sat Sep 05, 2015 5:20 pm
Forum: Pro Audio Design
Topic: Flat Phono Preamp Based on John's P10 and 2SK389
Replies: 248
Views: 328385

Re: Flat Phono Preamp Based on John's P10 and 2SK389

It's the same problem attempting a true balanced connection with RCAs and moving magnet carts. The balanced inputs work better with RCAs but only if the shield is grounded. Try to float the shield and it hums. This is SME's fault. In the 60's & early 70's, many pickup arm makers had 5 wire leads an...
by ricardo
Sun Aug 30, 2015 9:29 pm
Forum: Pro Audio Design
Topic: Flat Phono Preamp Based on John's P10 and 2SK389
Replies: 248
Views: 328385

Re: Flat Phono Preamp Based on John's P10 and 2SK389

rYou got a DiamondCut 8 or Audacity plug-in recommendation for RIAA? I'm afraid not. Gotta remember I'm a REAL beach bum. EDIT : Interesting paper at TDL-Tech: http://www.tdl-tech.com/arscj.pdf Looks like DC8 is recognized as having a fairly accurate RIAA phase response... I'm not sure these guys u...
by ricardo
Sun Aug 30, 2015 6:47 pm
Forum: Pro Audio Design
Topic: modified GFCI
Replies: 92
Views: 140483

Re: modified GFCI

The ground present solution worked fine dealing with the leaky appliances in my kitchen, but the bathroom outlet still showed a ground connection. Today I opened up that outlet and found an inadvertent short between neutral and the metal junction box, causing an accidental bootleg ground. When I fi...
by ricardo
Sun Aug 30, 2015 6:43 pm
Forum: Pro Audio Design
Topic: Flat Phono Preamp Based on John's P10 and 2SK389
Replies: 248
Views: 328385

Re: Flat Phono Preamp Based on John's P10 and 2SK389

but in reality the edge rates from cutting lathes and vinyl are just not very fast... True. Clicks do. Though I really wouldn't have thought it the ultrasonic harmonics created by mechanical distortion (mistracking) may not have high edge rates but they sure create a lot of ultrasonic energy. I'm c...