Search found 56 matches

by weroflu
Sun Nov 12, 2023 6:29 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 105
Views: 307201

Re: That1580 mini mixer

signal recorded. distorted and too quiet but it's sorta working. got a few questions about the 6261 with 2 wire lav inputs is there a better idea than balancing signal ended output from lavs to feed the 6261? since there's no phantom feed, can i leave out the 220u's in fig 17 ? tantalum ok for the 4...
by weroflu
Fri Feb 03, 2023 3:49 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 105
Views: 307201

Re: That1580 mini mixer

thanks for the link. read it and thinking on it.

for now it's not high priority as i'm still working on getting signal digitized.

just sent board order for revised adc, clock and mcu

fingers crossed things will start to work after this.

future versions might involve 626x to simplify things
by weroflu
Wed Apr 20, 2022 2:24 pm
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 105
Views: 307201

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 db gain is probably ok, but maybe w...
by weroflu
Wed Apr 20, 2022 4:25 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 105
Views: 307201

Re: That1580 mini mixer

Re: power supply, yes I had a few different power supply approaches along the way, but I'm very happy you brought this up now. I got a bit lazy for the last p/s rev. using +-5v rails. I was thinking 6v wall wart input would not be too wasteful if I only had to drop 1V for the +5v. Also 3.3V now need...
by weroflu
Tue Apr 19, 2022 10:07 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 105
Views: 307201

Re: That1580 mini mixer

I've been through so many revisions that a lot of the info from the older posts isn't so relevant. As of this revision my power supply is: 9v switching wall wart--> lt3045 regulator for +7v, +3.3v inverting converter 9v>-8v>lt3094>-7v boost converter >50v>lt3012 regulator>48v not much power concerns...
by weroflu
Tue Apr 19, 2022 6:31 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 105
Views: 307201

Re: That1580 mini mixer

I got as far as testing audio output from the master bus and testing simple audio recording from both a test tone fed to the master out bypassing the mixer section, and also the regular bus. All fails. I didn't have any test point on the preamp cards so I couldn't even probe signals there. My main s...
by weroflu
Mon Jun 07, 2021 11:48 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 105
Views: 307201

Re: That1580 mini mixer

can't do the polarity digital because signal is still analog at that point. the adc happens after the virtual earth summing: 5x2 analog mixer>> stereo analog buffer for adc >>stereo adc>>mcu>>microsd i thought about what you're saying (sorta) with nixing the 1240's. pro: save a stage, less noise pro...
by weroflu
Sun Jun 06, 2021 4:47 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 105
Views: 307201

Re: That1580 mini mixer

one preamp card is built but have not passed audio yet. i have some beta code for a linear audio meter loaded, have not gotten around to making it log yet. i paused building due to: spending some months trying to turn this from an analog mixer into a mixer/stereo adc/stereo recorder. right now the d...
by weroflu
Mon Feb 01, 2021 3:49 pm
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 105
Views: 307201

Re: That1580 mini mixer

Lots of progress. 328p mcu working, oled display working, mini joystick working, power supply working, and mcu section of the channel cards is working. Wayne you will like this new power supply, it is half the size of the last one. Double sided board about the size of two thumbnails New board order ...
by weroflu
Wed Dec 09, 2020 11:13 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 105
Views: 307201

Re: That1580 mini mixer

1.2k bias straight from the datasheet.

I don't have mute on this version.