Would anyone reading this thread have a schematic for a Langevin EQ252A or its rack mount equivalent, EQ270? This is a seven-band, "graphic" eq using passive bridged-T circuits.
A colleague has one that isn't working properly.
Thanks,
-j
Search found 25 matches
- Tue Jun 18, 2013 7:47 am
- Forum: Pro Audio Design
- Topic: LC filter experiments, in Pultec MEQ context
- Replies: 15
- Views: 31722
- Tue Jun 18, 2013 7:45 am
- Forum: Pro Audio Design
- Topic: Very low level hum and how to get rid of it
- Replies: 12
- Views: 22081
Re: Very low level hum and how to get rid of it
In the context of high-voltage supplies, point-to-point wired, for vacuum tube circuits, the advice I have been given is: connect the power transformer center tap directly to the first filter cap after the rectifier. Connect the audio circuit ground directly to the last filter cap in the smoothing n...
- Mon Jun 17, 2013 11:40 pm
- Forum: Pro Audio Design
- Topic: Presenting "The Leslieator" - a work in progress
- Replies: 10
- Views: 25893
Presenting "The Leslieator" - a work in progress
On Sundays I mix sound for a church and, while my setup is quite functional, I'm always trying to do a little more with a little less. Case in point: I currently have a stereo mic setup on a very nice Leslie 122 cabinet (driven, just as it is ordained in the scriptures, by a very nice Hammond B3.) T...
- Tue Apr 16, 2013 5:30 pm
- Forum: Pro Audio Design
- Topic: Recommended implementation for THAT1512
- Replies: 34
- Views: 59895
Re: Recommended implementation for THAT1512
It works. The gain adjustment is odd but I was expecting that, I don't have a pot of the appropriate value. I tested it, I'm getting a maximum of 48 dB of gain, which is less than I expected with a step-up transformer. I haven't measured the transformers yet, I may have a smaller step up than I expe...
- Sun Apr 14, 2013 4:53 pm
- Forum: Pro Audio Design
- Topic: Recommended implementation for THAT1512
- Replies: 34
- Views: 59895
Re: Recommended implementation for THAT1512
JR: My drawing may be misleading. The connections at the XLR out jack are shown as if they are made on the XLR connector but (+, –, E and G) will actually be made by their own 4-pin connector, either a Molex type or possibly an RJ-11 or RJ-45 snap-in type to save some room. Depends on what I have at...
- Sat Apr 13, 2013 9:07 pm
- Forum: Pro Audio Design
- Topic: Recommended implementation for THAT1512
- Replies: 34
- Views: 59895
Re: Recommended implementation for THAT1512
I've got a single mic preamp channel almost finished on perf board. I've built this first one as a standalone mic pre stage to feed a line mixer via XLRs, running off a battery supply (+/- 18V rails.) I want to hear what it sounds like before I build up a bunch of channels. It's in three little boxe...
- Wed Mar 27, 2013 11:25 pm
- Forum: Pro Audio Design
- Topic: Level Detectors, Absolute Value, Peak and RMS
- Replies: 42
- Views: 156189
Re: Level Detectors, Absolute Value, Peak and RMS
Likely, I'm missing something, but - Isn't the behavior of the peak of the wave a whole lot more important than the zero-crossing behavior for level indicator application? What does distortion of the rectified wave even matter here? Wayne: are you looking at that output behavior so critically becaus...
- Tue Mar 26, 2013 7:55 pm
- Forum: Pro Audio Design
- Topic: Recommended implementation for THAT1512
- Replies: 34
- Views: 59895
Re: Recommended implementation for THAT1512
So in looking at the existing circuit (LINEMIXERSchematic.jpg) I see a couple of things that interest me. 1. The buffer ahead of the existing clip indicator (IC1B) looks like a good place to pull off a pre-fader, pre-pan signal - if I roll my own clip indicator I can repurpose that send as a pre-fad...
- Tue Mar 26, 2013 7:35 pm
- Forum: Pro Audio Design
- Topic: Level Detectors, Absolute Value, Peak and RMS
- Replies: 42
- Views: 156189
Re: Level Detectors, Absolute Value, Peak and RMS
If you have any hope of becoming a design engineer, read all the posted schematics, then design one of your own... 8-) Hope. Hmm. I guess I do hope for that. "Instead of a bum, which is what I am," to quote Terry Malloy. I am at the point, with reference to this design issue, that I don't...
- Mon Mar 25, 2013 6:09 pm
- Forum: Pro Audio Design
- Topic: Level Detectors, Absolute Value, Peak and RMS
- Replies: 42
- Views: 156189
Re: Level Detectors, Absolute Value, Peak and RMS
Excuse me, Wayne, but in another thread, JR had assigned me to design my own peak detector. You've TOTALLY screwed THAT up. Now, I do NOT suffer from NIH and this is an embarrassment of riches. Thank you. But it seems like I'm going to miss a learning opportunity..... of course, understanding what t...