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- Fri May 08, 2009 9:51 pm
- Forum: Build
- Topic: Mid Side M-S Matrix Construction Information
- Replies: 121
- Views: 452852
Mid Side M-S Matrix Construction Information
This is a clone of the post in the original thread. We might want to put build questions in this thread. MS Mid Side Encoder/Decoder PC Boards: https://ka-electronics.com/shop/index.php?route=product/search&search=Simple%20MS Update 5/12/2015: PDF Assembly Instructions are here: https://www.ka-...
- Fri May 08, 2009 8:57 pm
- Forum: Pro Audio Design
- Topic: Mid Side M-S Matrix Uses No Precision Resistors
- Replies: 271
- Views: 640812
Mid Side M-S Matrix Construction Information
I've gotten a little behind on creating and posting documentation. Wayne is stretched thin. I've cloned this post in the Build Subforum. We might want to discuss build questions here: http://www.proaudiodesignforum.com/forum/php/viewtopic.php?f=7&t=262 Here's a preliminary bill of materials: 13)...
- Thu May 07, 2009 3:04 pm
- Forum: Pro Audio Design
- Topic: Old: A Direct-Coupled Input-Capacitorless Active Mic Preamp
- Replies: 212
- Views: 414340
Re: A Direct-Coupled Input-Capacitorless Active Mic Preamp
No problemo and a great question. IIRC correctly I measured the peak current into the 1510 it was around 8 mA vs. the >>3A when input caps are present. I tried just about every way I could to blow up a 1510. I failed, it didn't. That particular fault, when input caps are used (one input pulled up, t...
- Thu May 07, 2009 12:27 pm
- Forum: Pro Audio Design
- Topic: Old: A Direct-Coupled Input-Capacitorless Active Mic Preamp
- Replies: 212
- Views: 414340
Re: A Direct-Coupled Input-Capacitorless Active Mic Preamp
OK, here’s what I measured, although unexpected: AT 4033 serial 39XX DCR=~740K offset=6.8mV AT 4033 serial 90XX DCR=20K offset=0.3mV AT 4033 serial 95XX DCR=22K offset=0.7mV TLM103#1 DCR=9K5 offset=0.8mV TLM103#2 DCR=9K4 offset=0.9mv Schoeps CMC5 body DCR>2M offset=15.7mV (wow, checked it 3 times) ...
- Thu May 07, 2009 11:29 am
- Forum: Pro Audio Design
- Topic: Old: A Direct-Coupled Input-Capacitorless Active Mic Preamp
- Replies: 212
- Views: 414340
Re: A Direct-Coupled Input-Capacitorless Active Mic Preamp
I found that with some cap-coupled inputs it can indeed take awhile to settle, particularly the common mode voltage.
If the preamp has been off awhile it takes ages for the capacitors to re-form.
What sort of differential (pin 2 to 3) offsets are you seeing?
If the preamp has been off awhile it takes ages for the capacitors to re-form.
What sort of differential (pin 2 to 3) offsets are you seeing?
- Thu May 07, 2009 10:12 am
- Forum: Pro Audio Design
- Topic: Old: A Direct-Coupled Input-Capacitorless Active Mic Preamp
- Replies: 212
- Views: 414340
Re: A Direct-Coupled Input-Capacitorless Active Mic Preamp
Glad I thought to ask. When you get a chance you might try it with a couple of 6K81s pulled up to 48V.
If you don't have an easily obtainable 48V supply you can get 45V from the IP27-18 by stacking all three or use the dual 20V and a 9V battery in series.
I'm curious about Bruno's TLM103s....
If you don't have an easily obtainable 48V supply you can get 45V from the IP27-18 by stacking all three or use the dual 20V and a 9V battery in series.
I'm curious about Bruno's TLM103s....
- Thu May 07, 2009 9:05 am
- Forum: Pro Audio Design
- Topic: Old: A Direct-Coupled Input-Capacitorless Active Mic Preamp
- Replies: 212
- Views: 414340
Re: A Direct-Coupled Input-Capacitorless Active Mic Preamp
Wow, cool - thanks! What we're looking for is the offset developed by the microphone when phantom is applied through the customary 6K81 pull-ups. It cannot be loaded by a transformer but an active input, or just the pullup resistors as load, will tell us how symmetric the current draw is. The DC pot...
- Wed May 06, 2009 9:01 pm
- Forum: Pro Audio Design
- Topic: Old: A Direct-Coupled Input-Capacitorless Active Mic Preamp
- Replies: 212
- Views: 414340
Re: A Direct-Coupled Input-Capacitorless Active Mic Preamp
Thanks. Looks like the 4050s may be the ones which are not transformer output.
Anybody got a TLM103?
The Vos is <<1 mV. Not a smoking gun. Anyone else want to measure some phantom-powered mics?Pair of 4050s
0.2mV/0.7mV
Anybody got a TLM103?
- Wed May 06, 2009 4:42 pm
- Forum: Pro Audio Design
- Topic: Mid Side M-S Matrix Uses No Precision Resistors
- Replies: 271
- Views: 640812
Re: Mid Side M-S Matrix Uses No Precision Resistors - Boards 5/1
I just wanted to thank everyone who has ordered boards recently!
Wayne
Wayne
- Wed May 06, 2009 4:41 pm
- Forum: Pro Audio Design
- Topic: Old: A Direct-Coupled Input-Capacitorless Active Mic Preamp
- Replies: 212
- Views: 414340
Re: A Direct-Coupled Input-Capacitorless Active Mic Preamp
Thanks Roger. Hardly a smoking gun.
You might check to see what the DC resistance is across pins 2 and 3. That should tell us if there's a transformer there.
You might check to see what the DC resistance is across pins 2 and 3. That should tell us if there's a transformer there.