Search found 88 matches
- Fri Sep 01, 2017 3:32 pm
- Forum: Pro Audio Design
- Topic: Comparator oscillation in meter circuit - pollutes audio
- Replies: 14
- Views: 20891
Re: Comparator oscillation in meter circuit - pollutes audio
I'm attaching the schematic below. The circuit has negative power supply, so MTR_GND is 0V, _B- is -18V, VIRT_GND is something like -9V The grounding scheme might be the culprit as I'm using a V/2 as a decoupling point and now I don't think it was such a good idea. But if you see anything that may c...
- Fri Sep 01, 2017 3:43 am
- Forum: Pro Audio Design
- Topic: Comparator oscillation in meter circuit - pollutes audio
- Replies: 14
- Views: 20891
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...
- Sun Jul 12, 2015 3:31 am
- Forum: Pro Audio Design
- Topic: Minimizing ripple in multichannel preamp - Solved
- Replies: 3
- Views: 14501
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.
Sorry for confusion.
- Sat Jul 11, 2015 6:27 am
- Forum: Pro Audio Design
- Topic: Minimizing ripple in multichannel preamp - Solved
- Replies: 3
- Views: 14501
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...
- Mon May 04, 2015 6:30 am
- Forum: Pro Audio Design
- Topic: PCB layout - ground plane for PSU/star point
- Replies: 7
- Views: 20926
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...
- Sun May 03, 2015 5:00 pm
- Forum: Pro Audio Design
- Topic: PCB layout - ground plane for PSU/star point
- Replies: 7
- Views: 20926
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...
- Fri Oct 04, 2013 4:30 pm
- Forum: Pro Audio Design
- Topic: New: A Direct-Coupled Input-Capacitorless Active Mic Preamp
- Replies: 142
- Views: 395264
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...
- Fri Oct 04, 2013 2:26 pm
- Forum: Pro Audio Design
- Topic: New: A Direct-Coupled Input-Capacitorless Active Mic Preamp
- Replies: 142
- Views: 395264
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?
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?
- Wed Sep 25, 2013 5:48 am
- Forum: Pro Audio Design
- Topic: New: A Direct-Coupled Input-Capacitorless Active Mic Preamp
- Replies: 142
- Views: 395264
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...
- Wed Sep 25, 2013 4:50 am
- Forum: Pro Audio Design
- Topic: New: A Direct-Coupled Input-Capacitorless Active Mic Preamp
- Replies: 142
- Views: 395264
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...