Search found 54 matches

by weroflu
Wed Apr 20, 2022 2:24 pm
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 102
Views: 236855

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: 102
Views: 236855

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: 102
Views: 236855

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: 102
Views: 236855

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: 102
Views: 236855

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: 102
Views: 236855

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 4:49 pm
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 102
Views: 236855

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 12:13 pm
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 102
Views: 236855

Re: That1580 mini mixer

1.2k bias straight from the datasheet.

I don't have mute on this version.
by weroflu
Mon Dec 07, 2020 10:47 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 102
Views: 236855

Re: That1580 mini mixer

Boards ordered. First next step is just a physical dimension test on the jacks and edge connectors. I caught one error, which might turn into a positive... I rearranged the phantom blocking caps, which were previously 22uf - as I understand it this about the low end of what you want. I can only fit ...
by weroflu
Sat Nov 21, 2020 5:37 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 102
Views: 236855

Re: That1580 mini mixer

Oled: Show me how I can use lcd in a smaller footprint than what I'm using now. I managed to squeeze the 6th channel back in by offloading the p/s onto a mini card. Getting close to a board run and then I saw the That 6261, hmmm. It wouldn't be hard to add a master channel with gain/attenuation now....