Texar Prism Multiband Processor clone
« on: March 14, 2021, 08:38:14 PM »
New to the forum and wanted to post a recent project I have been working on. I already own a pair of Texar Prisms that I casually use and having studied the inner workings of it I decided to try an attempt at a modern spin without resorting to DSP and with reduced complexity.  The result is a PWM based design with a handful of components in a small SMD footprint to achieve the functionality of the more complex Texar M101 board. A microcontroller is the heart of the digital control and display function and emulates what was a mostly analog design on the original with some digital ICs for control.

At this point I have optimized the code to track alongside my original analog units and they perform much better than I originally anticipated for taking a simplistic approach to the design. What you see is the proof-of-concept prototype but if there is any interest I may proceed further and look at packaging the design into a more DIY friendly approach.


Re: Texar Prism Multiband Processor clone
« Reply #1 on: March 14, 2021, 08:42:07 PM »
Some envelope data of a sample track raw vs compressed.


Re: Texar Prism Multiband Processor clone
« Reply #2 on: March 15, 2021, 03:12:38 PM »
Very cool first post! 

I wasn't actually familiar with these, so I did a quick Google search and read a little.  Seems like they are a fairly particular unit (at least from what I found).  I guess they were intended as broadcast equipment, and I see a lot of chat about pairing them with an Optimod 8100 in that context.

How are you using them?  Do you like them as a standalone tracking/mixing compressor?

It's always great to see people working on new and interesting projects! 

Re: Texar Prism Multiband Processor clone
« Reply #3 on: March 15, 2021, 05:11:57 PM »
Yes the Texar/Optimod pair was pretty much a standard in the 80s up through the 90s. The station I worked at had a pair of them along with a Mod Sciences Stereomaxx and our modulation monitor needle barely moved just below 100% during program. It was a combo that could create loudness without being unbearable or with the density reduced it made for fuller content.

My analog pair is aged out of spec so I dont use them extensively. The Vactrols age and drift so renewing them and running a calibration procedure is required to bring them back to their 80s glory. If you spot a pair on eBay they usually go fast so theres still a user base out there.

Here is the history of the Prism  https://www.thebdr.net/wp-content/uploads/PDF/Audio/Processing/the-audio-prism-story.pdf


Re: Texar Prism Multiband Processor clone
« Reply #4 on: March 15, 2021, 08:51:24 PM »
Great article!

Doug Williams
Electromagnetic Radiation Recorders

"I think this can be better. Some kind of control that's intuitive, not complicated like a single knob" - Crusty

"Back when everything sounde


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