Search found 67 matches

by ilya
Fri Sep 01, 2017 3:43 am
Forum: Pro Audio Design
Topic: Comparator oscillation in meter circuit - pollutes audio
Replies: 14
Views: 11208

Comparator oscillation in meter circuit - pollutes audio

I'm using a rather standard metering circuit with full wave op-amp rectifier that feeds a string of LM339 comparators. Comparators outputs are connected to the string of LEDs that are fed from the constant current source. All well and good. I had this circuit working on the dual rails supply with no...
by ilya
Sun Jul 12, 2015 3:31 am
Forum: Pro Audio Design
Topic: Minimizing ripple in multichannel preamp - Solved
Replies: 3
Views: 11155

Re: Minimizing ripple in multichannel preamp

Ok. Turned out I measured wrongly. Forgot to short input pins 2 and 3. Once measured properly everything was fine.
Sorry for confusion.
by ilya
Sat Jul 11, 2015 6:27 am
Forum: Pro Audio Design
Topic: Minimizing ripple in multichannel preamp - Solved
Replies: 3
Views: 11155

Minimizing ripple in multichannel preamp - Solved

I'm building a 2-channel preamp based on 1073 circuit. Currently I have the 24V regulators on each preamp board, so I feed the unregulated DC from a PSU board (just a general bridge into the cap). Everything is fine when I have only 1 channel working. However, when I connect the second channel to th...
by ilya
Mon May 04, 2015 6:30 am
Forum: Pro Audio Design
Topic: PCB layout - ground plane for PSU/star point
Replies: 7
Views: 16250

Re: PCB layout - ground plane for PSU/star point

Thanks! That's what I tought as well. My current plan is to use a separate PSU board that includes bridge/reservoir caps for audio and regulation for +48V. Final regulation of power rails will be done on local preamp boards (for each channel individually). I'm going to lay out a star ground point at...
by ilya
Sun May 03, 2015 5:00 pm
Forum: Pro Audio Design
Topic: PCB layout - ground plane for PSU/star point
Replies: 7
Views: 16250

PCB layout - ground plane for PSU/star point

Gents, I'm laying out a PCB for one of my mic pre projects. I always made a full ground plane on the top layer, but recently I thought that there may be better ways. One thought was to make a separate ground plane for PSU and the rest of the circuit. The obvious question is where do you connect them...
by ilya
Fri Oct 04, 2013 4:30 pm
Forum: Pro Audio Design
Topic: New: A Direct-Coupled Input-Capacitorless Active Mic Preamp
Replies: 122
Views: 120895

Re: New: A Direct-Coupled Input-Capacitorless Active Mic Pre

Ok. I think I need to tell more about my project. I'm going to put 8 channels of these pres into 1RU enclosure. I'm planning to power the units from external PSU and also be able to daisy-chain several units so they can be powered from one PSU. Sooo... I have several goals in mind. First: minimal co...
by ilya
Fri Oct 04, 2013 2:26 pm
Forum: Pro Audio Design
Topic: New: A Direct-Coupled Input-Capacitorless Active Mic Preamp
Replies: 122
Views: 120895

Re: New: A Direct-Coupled Input-Capacitorless Active Mic Pre

Wayne,

I'm looking at 1606 line drivers. What do you think, is it sufficient to implement circuit from figures 7 and 8 in the datasheet (http://www.thatcorp.com/datashts/THAT_1 ... asheet.pdf) and put this after 1246s?
by ilya
Wed Sep 25, 2013 5:48 am
Forum: Pro Audio Design
Topic: New: A Direct-Coupled Input-Capacitorless Active Mic Preamp
Replies: 122
Views: 120895

Re: New: A Direct-Coupled Input-Capacitorless Active Mic Pre

In your scenario where some other device provides the phantom you would not want the phantom switch on this device to back-ground the 6K81 resistors since they would load the other source of phantom. The ground connection for the switch could be made an optional link. The choice of back-grounding o...
by ilya
Wed Sep 25, 2013 4:50 am
Forum: Pro Audio Design
Topic: New: A Direct-Coupled Input-Capacitorless Active Mic Preamp
Replies: 122
Views: 120895

Re: New: A Direct-Coupled Input-Capacitorless Active Mic Pre

ilya - Each channel can independently fly to whatever phantom voltage is present at the input between 0 and +48V. Every mic will be different and every channel can be different. If the phantom voltage is supplied by another device - and phantom is switched off on this device - it will still adapt t...
by ilya
Wed Sep 25, 2013 3:11 am
Forum: Pro Audio Design
Topic: New: A Direct-Coupled Input-Capacitorless Active Mic Preamp
Replies: 122
Views: 120895

Re: New: A Direct-Coupled Input-Capacitorless Active Mic Pre

Yes, you just have phantom switches for each channel. Just like a regular preamp. Each one operates independently. Ok, cool. I was concerned that once there's phantom on any channel, then the whole module flys to that. But now I see that this should make no problems for other channels. Another ques...