Search found 3705 matches

by JR.
Fri Mar 29, 2013 7:57 am
Forum: Pro Audio Design
Topic: Level Detectors, Absolute Value, Peak and RMS
Replies: 42
Views: 156211

Re: Level Detectors, Absolute Value, Peak and RMS

Wayne's scope traces are for a couple volts of signal FWIW the first pic was a 10 mV (peak) 20 kHz photo. I really should put a couple of trims on it and see where it bottoms out. https://proaudiodesignforum.com/images/jpg/Biased_Diode_Abs_Value_20kHz_10mV_Peak.JPG Yup, and you can already see how ...
by JR.
Thu Mar 28, 2013 3:35 pm
Forum: Pro Audio Design
Topic: Level Detectors, Absolute Value, Peak and RMS
Replies: 42
Views: 156211

Re: Level Detectors, Absolute Value, Peak and RMS

You're missing the crux of the biscuit (at least of my biscuit) Wayne's scope traces are for a couple volts of signal. As I have mentioned several times now the precision rectifier issue is a product of frequency and how low the level is. That deviation from perfect rectification around the zero cro...
by JR.
Wed Mar 27, 2013 11:58 am
Forum: Pro Audio Design
Topic: Recommended implementation for THAT1512
Replies: 34
Views: 59896

Re: Recommended implementation for THAT1512

So in looking at the existing circuit (LINEMIXERSchematic.jpg) I see a couple of things that interest me. 1. The buffer ahead of the existing clip indicator (IC1B) looks like a good place to pull off a pre-fader, pre-pan signal - if I roll my own clip indicator I can repurpose that send as a pre-fa...
by JR.
Wed Mar 27, 2013 11:53 am
Forum: Pro Audio Design
Topic: Level Detectors, Absolute Value, Peak and RMS
Replies: 42
Views: 156211

Re: Level Detectors, Absolute Value, Peak and RMS

If you have any hope of becoming a design engineer, read all the posted schematics, then design one of your own... 8-) Hope. Hmm. I guess I do hope for that. "Instead of a bum, which is what I am," to quote Terry Malloy. I am at the point, with reference to this design issue, that I don't...
by JR.
Tue Mar 26, 2013 12:24 pm
Forum: Pro Audio Design
Topic: Level Detectors, Absolute Value, Peak and RMS
Replies: 42
Views: 156211

Re: Level Detectors, Absolute Value, Peak and RMS

Yup, I remember that and Buff also sold a noise/level meter briefly. Somewhere in my lab I still have a small battery powered gain stage with an "A" noise shaping/weighting filter. handy to throw a fixed X dB gain with noise shaping in series to extend the measurement range of your bench, ...
by JR.
Tue Mar 26, 2013 9:53 am
Forum: Pro Audio Design
Topic: Level Detectors, Absolute Value, Peak and RMS
Replies: 42
Views: 156211

Re: Level Detectors, Absolute Value, Peak and RMS

Yup, the dirty secret about precision rectifiers is how they suffer from loop gain. I recall when I first fired up my prototype TS-1 with standard precision rectifier, I was reading a measurement noise floor well below -100 dB. But before patting myself on the back, I figured out I was seeing a meas...
by JR.
Tue Mar 26, 2013 8:42 am
Forum: Pro Audio Design
Topic: Level Detectors, Absolute Value, Peak and RMS
Replies: 42
Views: 156211

Re: Level Detectors, Absolute Value, Peak and RMS

But it seems like I'm going to miss a learning opportunity..... of course, understanding what these circuits DO is not a bad one either... Just build all of them and figure out which is best. You'll learn a lot from it. Symetrix used the Buff log detector though there does seem to be a bias resisto...
by JR.
Tue Mar 26, 2013 8:36 am
Forum: Pro Audio Design
Topic: Level Detectors, Absolute Value, Peak and RMS
Replies: 42
Views: 156211

Re: Level Detectors, Absolute Value, Peak and RMS

Excuse me, Wayne, but in another thread, JR had assigned me to design my own peak detector. You've TOTALLY screwed THAT up. Now, I do NOT suffer from NIH and this is an embarrassment of riches. Thank you. But it seems like I'm going to miss a learning opportunity..... of course, understanding what ...
by JR.
Mon Mar 25, 2013 6:07 pm
Forum: The Peabody Lounge
Topic: Is this green or just silly?
Replies: 5
Views: 12954

Re: Is this green or just silly?

In my GREEN theme, I am just nearing the end of my first heating season since i replaced my in-wall air conditioner with dual purpose heat pump. I use built in timer to turn it completely off at night and warm up in the morning before I get up. tracking my electricity usage vs year earlier it looks ...
by JR.
Mon Mar 25, 2013 4:32 pm
Forum: Pro Audio Design
Topic: Level Detectors, Absolute Value, Peak and RMS
Replies: 42
Views: 156211

Re: Level Detectors, Absolute Value, Peak and RMS

Yup, exactly,, That one Buff schematic is a nice object lesson in smart log domain design. Some subtle stuff going on in there, and I suspect many got in trouble trying to copy it without understanding details. While he was not allergic to using lots of trim pots... a habit Peavey broke me of. My si...