Search found 17 matches

by Craig Buckingham
Wed Jun 10, 2015 10:38 pm
Forum: Document
Topic: DC Servos and Digitally-Controlled Microphone Preamplifiers
Replies: 12
Views: 21258

Re: DC Servos and Digitally-Controlled Microphone Preamplifi

Servo is more complex than AC coupling for sure, but I would say maybe equally or less complex than a hybrid design that is DC stable without the need for a servo. Putting a monolithic matched pair front end on an op-amp (curse the thought of degrading the monolithic pair by marrying it with an op-a...
by Craig Buckingham
Wed Jun 10, 2015 6:43 am
Forum: Document
Topic: DC Servos and Digitally-Controlled Microphone Preamplifiers
Replies: 12
Views: 21258

Re: DC Servos and Digitally-Controlled Microphone Preamplifi

In my experience servos are an evil best avoided at all costs. They add a whole lot of disadvantages of their own. What's wrong with a dual current sink on input differential LTP and gain setting resistor set between the LTP emitters or emitter degeneration resistors? With good match and trimming co...
by Craig Buckingham
Sat Jun 06, 2015 3:39 am
Forum: Document
Topic: reducing distortion in transfer gates
Replies: 2
Views: 7425

Re: reducing distortion in transfer gates

What a terrible thing to do to an audio signal.
by Craig Buckingham
Sun May 10, 2015 1:18 am
Forum: Pro Audio Design
Topic: PCB layout - ground plane for PSU/star point
Replies: 7
Views: 20707

Re: PCB layout - ground plane for PSU/star point

I've always preferred ground plane on the opposite side of the component layer to have much greater coverage with less irregularities caused by components eating up the ground plane real estate. Running signal and power on the component side with traces, no power planes. Does a star return on a PCB ...
by Craig Buckingham
Wed Jan 21, 2015 8:18 am
Forum: Build
Topic: Simple pcb design program
Replies: 28
Views: 107765

Re: Simple pcb design program

Is this too simple for what you need? http://www.expresspcb.com/ EDIT: Maybe you are tied into using their PCB services. EDIT2: Just read the other thread about PCB design programs. Forget what I said. I used to use a DOS version of Protel and really loved using keystrokes. It's amazing how many you...
by Craig Buckingham
Fri Jan 16, 2015 9:23 am
Forum: Pro Audio Design
Topic: Distortion and source impedance in JFET-input op amps
Replies: 13
Views: 31064

Re: Distortion and source impedance in JFET-input op amps

That OP seems to be a little mmm well actually kind of sucks IMO. Class B with some deadband (crossover region) help from R50. I can see why it would want to oscillate with capacitance on its output. R50 is between the class B stage and the feedback loop. That junction feeds the OP. So it seems to m...
by Craig Buckingham
Thu Jan 15, 2015 8:12 am
Forum: Pro Audio Design
Topic: Distortion and source impedance in JFET-input op amps
Replies: 13
Views: 31064

Re: Distortion and source impedance in JFET-input op amps

I'll have a stab at this from an analysis point of view. Mind you I don't believe I have any practical experience with issues that may necessitate the use of R8. I read the previous analysis regarding breakthrough and I am not arguing that side when the pot wiper is at ground. What I see is a DC com...
by Craig Buckingham
Mon Jan 12, 2015 10:44 pm
Forum: Document
Topic: Nichicon Audio Capacitor Page at Mouser
Replies: 8
Views: 13999

Re: Nichicon Audio Capacitor Page at Mouser

Thanks for sharing your experience JR. When I first started doing this stuff I took many dead ends. Had to find my way back out many times. It doesn't happen that much now. I suffer from very little expectation bias anymore, it was a long time ago that emotional trait was dispensed with. I have no e...
by Craig Buckingham
Mon Jan 12, 2015 10:43 am
Forum: Document
Topic: Nichicon Audio Capacitor Page at Mouser
Replies: 8
Views: 13999

Re: Nichicon Audio Capacitor Page at Mouser

It was a long time ago Ricardo. It was coupling an audio signal between a custom developed DAC and power amplifier. In that exercise the coupling caps were compared to each other and replaced with copper wire as the final test. All tests were done by ear. No test equipment was used. It was pretty ea...
by Craig Buckingham
Sat Jan 10, 2015 10:06 pm
Forum: Document
Topic: NXP (Nexperia) Matched Small Signal Transistor Pairs
Replies: 1
Views: 7425

Re: NXP Matched Small Signal Transistor Pairs

I understand these, and many others like them, are two singles sharing a common package rather than a single monolithic die with two transistors.

I am currently using the BCV62 for a current mirror in a design for a high performance motorsport application.