Pro Audio Design Forum

I've rebuilt the prototype and have a bunch of updates to provide soon but stumbled upon an interesting thing about microphones while poking around this circuit with the 'scope: Some phantom-powered mics have a significant low frequency common mode component due to internal dynamic signal currents....

"The 555 Timer Was Just The Beginning For Hans Camenzind," EDN Article, November 28, 2012. http://electronicdesign.com/article/analog-and-mixed-signal/555-timer-beginning-hans-camenzind-74715?NL=ED-04&Issue=ED-04_20121203_ED-04_72 http://electronicdesign.com/content/content/74715/7471...

I rebuilt the DC-Coupled Input Capacitorless Preamp with a THAT1570. The output is recovered by the AC-Coupled high impedance line amp followed by a double-balanced differential amp. All I can say is wow. This thing rocks. Here is spectrogram of the noise floor with the circuit built on an open pro...

Audio Circuits Using the NE5532, NE5533 and NE5534, Philips AN142, 1984. Just found a copy of this online and thought it needed to be in documents. There's an interesting discussion on the 5532s input clamp diodes I had forgotten about. https://www.ka-electronics.com/images/pdf/NE5532_NE5534_Audio_...

The more I look at using the THAT1570 or THAT1583 in this project the more I like it. The 1570 has the performance improvements THAT write about in the datasheets but in this circuit the 1510/1512 have one thing going against them that require a work-around. The 1510 and 1512 realize common mode re...

Just did a +60dB gain noise comparison with a 150R source and ~100 kHz measurement BW. Servo vs. Cgain the difference was perhaps 0.25 dB in favor of the 4700uF/6.3V. EDIT: Found an error in referencing one of the input bias resistors: There's no measurable difference with or without the servo. Also...

Thanks JR. I just re-built the "differential Deboo" using 1% resistors and the overall offset correction is far better than I thought. (Helps to practice what one preaches. :lol:) I'm seeing the differential output offset pegged at <<1 mV at all gain ranges with either a 10K or 150R input ...

I'm looking at using a THAT1570 or THAT1583 in a design without the digital gain controller and needed a servo. ...So I came up with a fully-differential form of the Deboo Integrator we used to servo the THAT1510. You may recall that the THAT1510 provides a single-ended output to feed the servo but...

Thanks ricardo. My thinking was I'd take 66V to the actual preamp board and put the 48V ripple eater there so there is very limited opportunity for it to see a dead short. Glad you agree that it would not be required. I'm looking at what it would take to use a 1570/1583 in this application. I think ...

ricardo - Your 48V supply looks very clean. I noticed that you'd built in short-circuit protection since it appears to enter a cable. I'm thinking about feeding the preamp regulated 66V from the PSU and then putting the 48V ripple eater on the preamp board. Been mulling whether I should provide 48V ...