Search found 54 matches

by weroflu
Sat May 06, 2017 4:28 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 230498

Re: That1580/1510 mini mixer

It looks like to me that you need a pad at the output of the DRV134 and run the PicoScope out near FS. Run picoscope sign gen full scale (2v) to increase s/n ratio ? Already too hot for the mic input, but add in gain of 2 from the drv134 and it needs a pad. 600ohm output of the sig gen into 10k inp...
by weroflu
Fri May 05, 2017 12:03 pm
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 230498

Re: That1580/1510 mini mixer

I bypassed the preamp and just fed the picoscope sig gen sweep back to 10x probes. First file is Y axis set to average. Second file is Y axis set to peak hold.

I don't know the answer to how does p.s. produce attenuated 1mV signal.
by weroflu
Fri May 05, 2017 10:50 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 230498

Re: That1580/1510 mini mixer

<<You have an unbalanced PicoScope output feeding a DRV134 which then feeds the balanced mic input with gain.>> Correct. I think attenuation is not necessary because the sig gen output range is 1mV - 2V. The output of the preamp is connected to 10x probes which attenuate the signal by a factor of 10...
by weroflu
Fri May 05, 2017 9:41 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 230498

Re: That1580/1510 mini mixer

Picoscope signal generator 20hz-20khz sweep, into drv134, into preamp card, output post pan/pre summing into scope

Still getting frequency dependent gain unless i'm not measuring correctly. Gain is set to 30db, which is what I see here from about 600hz-20khz.
by weroflu
Thu May 04, 2017 4:37 pm
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 230498

Re: That1580/1510 mini mixer

Update: something innocuous like testing my noob summing card turned into a disaster. I had a bridge on one of the backplane connecters from 48v to left out. Lots of chips got real hot and died, no smoke though. Note to self, don't put 48v bus rail next to left/right outputs. I must have also fried ...
by weroflu
Sun Apr 30, 2017 7:24 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 230498

Re: That1580/1510 mini mixer

Scoped the differential out on the 1580... only one side is showing signal. Now to find out if the problem is on the input or output, though there's nothing going on at the ouput aside from two traces and two vias. Also reflowed a new preamp card, same problem as the previous one. Edit: found someth...
by weroflu
Sat Apr 29, 2017 5:01 pm
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 230498

Re: That1580/1510 mini mixer

Sure I can generate tones. Do they need to be fed balanced into the 1580 though? There are plenty of linux soundcard/scope apps. I should probably learn how to use the pico though. Tuesday I can dead bug a drv134. I'll have a bnc adapter/cable by then as well. I mistakenly bought the wrong coax toda...
by weroflu
Sat Apr 29, 2017 2:13 pm
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 230498

Re: That1580/1510 mini mixer

I'm on a linux box. Trying to come up with the easiest way to diagnose the mic preamp signal. Then I can get to the fun stuff like meters and proper panning. At my disposal are android phone picoscope with 600ohm bnc unbalanced signal generator, two 1x/10x probes, two scope input channels, no bnc ca...
by weroflu
Sat Apr 29, 2017 12:32 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 230498

Re: That1580/1510 mini mixer

frequency.jpg
frequency.jpg (238.59 KiB) Viewed 10449 times
Android phone stereo signal generator out, right channel phase inverted, in to preamp card, usb adc interface/audacity, 20hz -20khz sweep

https://instaud.io/Urp
by weroflu
Fri Apr 28, 2017 9:09 am
Forum: Pro Audio Design
Topic: That1580 mini mixer
Replies: 101
Views: 230498

Re: That1580/1510 mini mixer

No headohone amp planned re: cmos switches, I thought about those for phantom, pan and phase as was intended from the 5171 designers but I don't know what ground noise problems await so I went for analog. Plus, the intended use for this box is set and forget, set gain, pan, phantom and use it to rec...