Search found 499 matches: servo

Searched query: servo

by mediatechnology
Thu Apr 21, 2022 9:27 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 232989

Re: That1580 mini mixer

It looks like you'd have to servo into the input bases since one emitter has Rg in series.
by weroflu
Wed Apr 20, 2022 2:24 pm
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 232989

Re: That1580 mini mixer

Yes I looked at the 626x a few times. Most recently I didn't like the low-ish gain, no servo and, worse distortion figures on the preamp than the 1580. Thinking about it now, I could fit 2 470uF 10v cg's on a preamp card since I would only need 2 or 3 cards, 39/34 ...
by weroflu
Tue Apr 19, 2022 6:31 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 232989

Re: That1580 mini mixer

... sheet says it swings to +-4v. So everything following I was thinking max swing is 8v p/p. Do I need ac coupling - C11 and C12, or does the servo on the 5171 eliminate enough dc at the output of the 1580? Figure 12 does not show any caps. https://statics.cirrus.com/pubs/appNote/an241-1.pdf ...
by mediatechnology
Mon Mar 14, 2022 3:45 pm
Forum: Pro Audio Design
Topic: Component Matching Minimizes IM Distortion in the Demrow-Cohen Balanced Front End
Replies: 5
Views: 1382

Component Matching Minimizes IM Distortion in the Demrow-Cohen Balanced Front End

... Balanced Front End With Hans Polak's help I recently redesigned the Flat Moving Coil Preamp PC board. With highly-mismatched pairs the servo control point in the original design increased IM distortion because it varied collector current. By moving the servo injection point to the emitters ...
by mediatechnology
Fri Feb 18, 2022 8:36 am
Forum: Build
Topic: Flat Balanced Input Moving Coil Phono Preamp Construction Information
Replies: 55
Views: 133022

Re: Flat Balanced Input Moving Coil Phono Preamp Construction Information

... The flat moving coil preamp doesn't require the thermal hat but I found that the servo activity at infrasonic frequencies is far less due to greater thermal mass and greater device coupling. If a nut seems like overkill gluing the ...
by mediatechnology
Tue Jan 25, 2022 3:49 pm
Forum: Pro Audio Design
Topic: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851
Replies: 499
Views: 435478

Re: A Low Noise Balanced Input Moving Coil Preamp Using the ZTX851

I've updated this design with a new PC board. Hans Polak convinced me that I should use emitter servo injection to reduce ZTX851 matching requirements. In the process we discovered that huge improvements in IMD2 distortion could be realized by matching resistors and C4/C5. ...
by mediatechnology
Tue Jan 25, 2022 3:41 pm
Forum: Build
Topic: Flat Balanced Input Moving Coil Phono Preamp Construction Information
Replies: 55
Views: 133022

Re: Flat Balanced Input Moving Coil Phono Preamp Construction Information

Updated January 25, 2021: A new PCB version, assembly instructions and Project Manager link are available. Improvements include a simpler servo, selected components to improve CCIF IMD2 distortion and an output pad for head amp applications.
by mediatechnology
Thu Dec 30, 2021 11:15 am
Forum: Pro Audio Design
Topic: A Differential Deboo Integrator to Servo Mic and Low-Level Preamps
Replies: 14
Views: 40694

Re: A Differential Deboo Integrator to Servo Mic and Low-Level Preamps

What I found by measurement was that as the offset needing correction grew, servo authority diminished.
The gain error was in addition to static offset errors in the servo.

In the example I gave earlier for the headphone amp a trim was inserted in Rg.
Not a good solution however.
by terkio
Thu Dec 30, 2021 11:05 am
Forum: Pro Audio Design
Topic: A Differential Deboo Integrator to Servo Mic and Low-Level Preamps
Replies: 14
Views: 40694

Re: A Differential Deboo Integrator to Servo Mic and Low-Level Preamps

In the conventional configuration, you do not need any matching. The important point, then, is the leakage resistor of the capacitor. This resistor gives the DC gain that comes in the residual error. ( A perfect integrator gives a zero error, because it has infinite gain ). One can calculate the err...