Search found 5475 matches

by mediatechnology
Mon Feb 09, 2009 7:11 am
Forum: Pro Audio Design
Topic: Help with parallel & summing with THAT IC's
Replies: 13
Views: 26057

Re: Help with parallel & summing with THAT IC's

I didn't exactly say the right thing. One of the inputs has to have a DC path, not necessarily to ground. If you tie one of the 9Ks to an op amp output (as you intend to do) the bias current will have a DC path. Both inputs (pins 1 and 3) cannot be AC-coupled since there's no DC path for Ibias. If y...
by mediatechnology
Sun Feb 08, 2009 5:11 pm
Forum: Pro Audio Design
Topic: Help with parallel & summing with THAT IC's
Replies: 13
Views: 26057

Re: Help with parallel & summing with THAT IC's

1. in the parallel section can a 1246 drive 2x 1646's? Yes, but what Roger said. 2 in the summing section, can i add a mute switch and attenuator where indicated? What Roger said. 3. and can i use the 1240 in summing mode as the data sheets specifies using the ref input so you have two matched 9k i...
by mediatechnology
Sun Feb 08, 2009 3:45 pm
Forum: Pro Audio Design
Topic: A Stereo Width Control Using the THAT1240
Replies: 10
Views: 36480

Re: A Stereo Width Control Using the THAT1240

Yes, exactly. Though a center detent may not be necessary. The center is fairly wide. Most of the action is near the ends. I'd say about a third of the rotation in the center is subtle. The outer thirds are where stuff starts to happen. An ideal solution is a dual stepped switch with a bias resistor...
by mediatechnology
Sun Feb 08, 2009 3:37 pm
Forum: Pro Audio Design
Topic: Mid Side M-S Matrix Uses No Precision Resistors
Replies: 271
Views: 641004

Re: Mid Side M-S Matrix Uses No Precision Resistors

Guys - I just did some crosstalk measurements on the matrix board after modifying it. In precision bypass mode* the 20 kHz crosstalk was: L into R -81.5 dBu R into L -75.5 dBu * Full encode/decode but with the encoder's 1646 and the decoder's 1246 bypassed. From points C to F here: http://www.picoco...
by mediatechnology
Sun Feb 08, 2009 3:32 pm
Forum: Pro Audio Design
Topic: A Stereo Width Control Using the THAT1240
Replies: 10
Views: 36480

Re: A Stereo Width Control Using the THAT1240

I'm OK but one thing, I'm confused by the padding resistor you mention? we are talking about the 2x 22k resistors? Yes, those are the padding resistors for an ideal pot. With an inexact pot (all those without ground taps in the center), one of the 22Ks will have a third resistor in parallel to make...
by mediatechnology
Sun Feb 08, 2009 10:36 am
Forum: Pro Audio Design
Topic: A Stereo Width Control Using the THAT1240
Replies: 10
Views: 36480

Re: A Stereo Width Control Using the THAT1240

1. the potential divider resistors across the pot,is there a value suggestion here? or just trial and error? you mention a trimmer also, would this replace and sit in any position of the divider? I think I used 22K resistors and the reason for choosing that value was to give it a better "feel....
by mediatechnology
Sat Feb 07, 2009 12:33 pm
Forum: Pro Audio Design
Topic: Mid Side M-S Matrix Uses No Precision Resistors
Replies: 271
Views: 641004

Re: Mid Side M-S Matrix Uses No Precision Resistors

The simpler 1240 can be used stand-alone.
by mediatechnology
Fri Feb 06, 2009 11:44 am
Forum: Pro Audio Design
Topic: Mid Side M-S Matrix Uses No Precision Resistors
Replies: 271
Views: 641004

Re: Mid Side M-S Matrix Uses No Precision Resistors

Thanks. The circuit shown in the link is simpler for a general-purpose width control. You could use it ahead or behind the M-S matrix just as long as the signal is in the "left/right" domain. The matrix in this thread lends itself to altering width by varying the M-S ratios in the insert l...