Would love to see videos with this type of explaination + good visuals like these for FET, VCA and vari-mu compressors as well! This vid is so clear and comprehensive.
Sir your videos are simply amazing you can not imagine how your soldering videos helped me, at this moment I don’t have the economic option to make a Patreon contribution but that doesn’t mean that I could not comment to give a special thanks for sharing your valuable knowledge not just for the knowledge but for the kindness and precision to genuinely share your well articulated point so again thank you very much, best regards from México 🇲🇽 City
Thank you for your kind comments. That's as good as a donation to me. A matter of fact I've paused my Patreon account because I've been too busy to generate new content. Hope to have new videos this year.
This video is the most amazing thing how i ve ever saw for my 40 years of life) i started with russian vintage radio tube module back in 80th when i was thee years old)) i remember that feelings and now i am a sound engenier and producer making tv show and series production, between that events) i ve been working on a big studio with many analog synths...tonight i was searching for parameters of la3a to set my FABFILTER compress the same way and have found this video...I ve got a lot of feelings when i ve got all answers and that power of deconstracting of serious vintage hardware like back to my childhood days)) thank you so much! Already subscribed
Great video, love the in-depth explanation as I'm getting into doing my own electronics. But what I really took away from this was just how good the hardware sounds on that comparison section -I guess nothing beats the real thing. I can't afford to buy any real hardware so I guess I'd better build my own.
Amazing when the lights went off. I had no idea about that. Re the music, problem is the original is already a finished mixed song. The big difference comes with raw sound then adding a compressor.
Mystery solved. I always wondered just how optical compressors do what they do. And now I do! Thanks! So, now it makes me wonder and have to ask, “with the advent of multi frequency lasers, has anyone developed opamp circuits that utilize nano-metric frequencies to build a high speed multi-band opamp?”
Those audio samples at the 10 minute region were not level matched quite well enough. Try normalizing all the audio files to something like -1dbs after the processing
Electroluminescent light sources like this are brighter at higher frequencies, though in practice I see them get dimmer after a kHz or so, this may differ depending on the manufacture method and choice of phosphor. If the audio waveform is being fed directly into the EL panel, the effective controlling variable won’t be the input waveform’s amplitude, but rather the amplitude of the differential of the input waveform. With the taper off. So I’d expect it to be much worse at attenuating bass than mids, sparkly loud cymbals would probably get through too.
Interesting, I don't have a unit handy to observe this, but I will say in general with music low mid and low frequencies at at a much higher amplitude than higher frequencies. The manual somewhat contradicts itself. Page 7 " The amount of light depends on the applied voltage and frequency"...... There is a a high frequency boost on the rear for gain reduction. ( similar to dessing ) The manual states in regards to this control. Page 12 of the manual. " If the control is set to the flat position, the LA 3A will provide equal reduction at all frequencies" .
I would really like to see what the frequency response of the light sensitive resistor is a I would imagine that the resistor reacts differently to say a sinusoidal wave (I realize music is way more complex and can't be reduced to a sine tone!) at 80Hz vs one at 1,000Hz. Thanks for making this awesome video!
Interesting question, but my guess is the light variations in brightness might actually average the level and filter out some of the high frequency information. In that a tone at 1khz might be the same or similar brightnes as a tone at 10 khz at the same level but I'm not sure. Similar to a VCA compressor that converts a music signal to a fluctuating DC level to control the VCA level.
I've got a bogen/tech-craft TCC-200 that I can find absolutely no info on at all, they've got these mic preamp cards with a 'raysistor' that is a small crystal sized optical cell, weird little thing but it sounds pretty great all things considered
Hm... This thing does make me wonder. Very quick photosensors have been around for audio playback on films for a very long time. As they output the recorded sound from the film they need to be able to work in thousands of a second of time. Maybe these sensors were deliberately chosen for this compressor because the attack and release of those particular sensors would suit a compressor. As in, not because they were quickest possible but instead because they were a bit slower. It doesn't have to reproduce the frequencies. Just control a fader according to the peaks and valleys of the overall soundwave.
Actually I looked at this closely before posting this video. For film sound a light sensitive vacuum tube was used. I had thought a photo resistor was used but I couldn't find any case as the slow release limits bandwidth.
What are the properties of the transformer to drive the EL panel ... and what kind of substitutes are available today and be equal to the old days. a German made transformer by Block? i tried a experiments with a simple old rusty 220 Volt to 9 Volt transformer hooked in reverse to my modular synthesizer via a simple 2SC945 transistor and connected a VCO to the base of the transistor and measured something like 200 V, i had to place 1k on the collector sourcing from the power rail, higher values where not good, having the scope on 50 volt per division, covering 4 divisions. Does Würth have something in their catalog that could serve? these yellow things you find on pcb's. The EL panel needs something like 110 V, did you measure.
@@biasedaudio i might have found something, not very expensive, but i gotta buy several models too see and find out. ratios of 1:50, 1:100, 1:200 and multiple windings. pretty small. it's just you don't know the requisitions from the original designers.
Thank You Alan! I didn't compare to other. Might in a future episodes. Always wanted to do a series of real gear vs plugins. I will take a look at the apogee stuff. Thank You again.
This is so cool! Can you do one on the LA-2 or 2A? like explain how the tubes are involved. Is it the make up gain stage or the output? and then compare it to the UAD LA-2 or 2A. They have the spark plugs now that you can run natively if you don't have an Apollo
Brandon I would if I had some more time but due to the similarities between the la3a and the LA 2A I doubt I'll get around to it. They're almost identical in the LA 2A of vacuum tube is used as the makeup game instead of transistors in the la3a and the only other real difference is the la3a has an interstage transformer to increase the voltage to the electroluminescent panel.
Okay. This is very good stuff. BUT!! when I look up electroluminescence I can’t find the history of it. You’re talking about a light source faster than incandescent but older than LED tech. So… pleeeeeease elaborate because I can’t find it anywhere and I was hoping I would find it here. Anyone can answer this question. Thank you.
Also, who in their right mind wouldn’t design something that showed off visible light operation? I suppose because outside light could interfere. But I still want to know how pre LED EL worked. Or at least what it was made of.
I googled electroluminescent panel and came up with tons of information and they are still sold. One reference I found says they were invented in 1958. en.wikipedia.org/wiki/Electroluminescent_display aopa.org/news-and-media/all-news/2018/october/09/aircraft-maintenance-electroluminescent-panel-repair patents.google.com/patent/US3306770
Why is the T4B encapsulated if it works perfectly fine without the metal capsule? This is a very introspective video. I would love to see how the T4B works with a iPhone 11+ recording (because it's thin enough to fit inside the LA-3A and records in low light very sharp) while the cover is placed on LA-3A cover is placed on top. While the Pro Tools session is screen recorded and the meters are being recorded simultaneously by another camera on the outside. Then We can see how all of it works together in real time.😁
The T4 is incapsulated to first keep light out, I turned off all the light to shoot this video. Not practical in a studio environment ! also for audio shielding I would guess.
Well I haven't tested and looked for that. I went with the UREI measured curve. In the days that this unit was released 3 to 6 to compression was a more normal way to operate. I remember being taught back in the day if you compressed more than 6 db you should reduce you preamp gain . 10 dB was considered a lot of compression. In the 80's it became more common to really smash stuff with compressors. As well with the advent of digital compressors with few artifacts heavy limiting has become more common. Under those circumstances I'll assume the Light will hit max brightness or photo resistor will become saturated. I even looked online and viewing the "S" shaped charts where the gain reduction starts to tilt up is in the range of 20 dB of gain reduction. So I'll assume the term s shaped is accurate but only under extreme circumstances. Not really sure of what the advantage of hitting the top of the "S" in the curve would be.
Using plugins will make all compressors become FET as computer using billions of transistors inside, not talking about digitizing it. Use an actual and real compressors as possible if you want to experience the real ones.
Very cool when you witched the lights off to show the T4B action!
after 10 years of experience i learned something new.
I love the sound of these compressors but never quite understood how they worked, until now. Thanks a lot, great video!
Glad you liked it!
One of the best videos about gear that I ever watched on TH-cam
Would love to see videos with this type of explaination + good visuals like these for FET, VCA and vari-mu compressors as well! This vid is so clear and comprehensive.
Now that is really amazing Wish i had a teacher like you
"Brilliant" presentation! thank you!
Sir your videos are simply amazing you can not imagine how your soldering videos helped me, at this moment I don’t have the economic option to make a Patreon contribution but that doesn’t mean that I could not comment to give a special thanks for sharing your valuable knowledge not just for the knowledge but for the kindness and precision to genuinely share your well articulated point so again thank you very much, best regards from México 🇲🇽 City
Thank you for your kind comments. That's as good as a donation to me. A matter of fact I've paused my Patreon account because I've been too busy to generate new content. Hope to have new videos this year.
Showing us the stuff we would never see otherwise…awesome!!
By far the best opto video I’ve seen, really good good info
I would love to see something like this for pre amps and DIs.
thank you from Argentina, first time im actually getting this stuff. incredible showcase!
What a well-produced wildly informative video, Brad! I am on board. Thank you so much.
Optical compressors are way cooler to me now thanks for the video 🤘💀🍻🔥
more videos plz 1176, dbx 160, LA2A, SSL G series, API 2500 and...
I always wanted to see how its triggered!! Thanks!
Great content and production. Thank you!
"Brilliant" presentation! Thank you SO much!
This is really one of the best channels I found on TH-cam! Thank you so much for this!!
Wow, thank you!
This video is the most amazing thing how i ve ever saw for my 40 years of life) i started with russian vintage radio tube module back in 80th when i was thee years old)) i remember that feelings and now i am a sound engenier and producer making tv show and series production, between that events) i ve been working on a big studio with many analog synths...tonight i was searching for parameters of la3a to set my FABFILTER compress the same way and have found this video...I ve got a lot of feelings when i ve got all answers and that power of deconstracting of serious vintage hardware like back to my childhood days)) thank you so much! Already subscribed
Simply amazing, thanks for the detailed explanation!
Thank you very much for the video, I really like it!
Now I know🙏🏾🙏🏾🙏🏾Thank you sir
I love this chanel, Ty for all.
Great video, love the in-depth explanation as I'm getting into doing my own electronics. But what I really took away from this was just how good the hardware sounds on that comparison section -I guess nothing beats the real thing. I can't afford to buy any real hardware so I guess I'd better build my own.
Amazing when the lights went off. I had no idea about that. Re the music, problem is the original is already a finished mixed song. The big difference comes with raw sound then adding a compressor.
True but unfortunately I have the problem of needing to use copyright clear music on TH-cam
@@biasedaudio yep. No problems, It was an excellent video, really good.
This video is great, thanks for making it.
And thank you for all the hard work you do for online audio education as well.
Thank you so much for getting right to the heart of my very favorite kind of compression! Gorgeous. Just gorgeous.
Useful info that is perfectly delivered
Thanks so much for that video!
Mystery solved. I always wondered just how optical compressors do what they do. And now I do! Thanks! So, now it makes me wonder and have to ask, “with the advent of multi frequency lasers, has anyone developed opamp circuits that utilize nano-metric frequencies to build a high speed multi-band opamp?”
Really great video! Thanks alot!
You're very welcome!
fascinating! many thanks for that kind of insights!
Those audio samples at the 10 minute region were not level matched quite well enough. Try normalizing all the audio files to something like -1dbs after the processing
Great video! But I had a hell of a time hearing the difference in the shoot out.
this is so fascinating from an engineering point of view
Brilliant ❤️
Excellent, detailed and informative. Thanks!
Greetings :) Amazing video!! Thank you so much! :)
GENIUS!
Very interesting and informative, thanks!
Electroluminescent light sources like this are brighter at higher frequencies, though in practice I see them get dimmer after a kHz or so, this may differ depending on the manufacture method and choice of phosphor. If the audio waveform is being fed directly into the EL panel, the effective controlling variable won’t be the input waveform’s amplitude, but rather the amplitude of the differential of the input waveform. With the taper off. So I’d expect it to be much worse at attenuating bass than mids, sparkly loud cymbals would probably get through too.
Interesting, I don't have a unit handy to observe this, but I will say in general with music low mid and low frequencies at at a much higher amplitude than higher frequencies. The manual somewhat contradicts itself. Page 7 " The amount of light depends on the applied voltage and frequency"...... There is a a high frequency boost on the rear for gain reduction. ( similar to dessing ) The manual states in regards to this control. Page 12 of the manual. " If the control is set to the flat position, the LA 3A will provide equal reduction at all frequencies" .
Excellent!!
Thank you!
I would really like to see what the frequency response of the light sensitive resistor is a I would imagine that the resistor reacts differently to say a sinusoidal wave (I realize music is way more complex and can't be reduced to a sine tone!) at 80Hz vs one at 1,000Hz. Thanks for making this awesome video!
Interesting question, but my guess is the light variations in brightness might actually average the level and filter out some of the high frequency information. In that a tone at 1khz might be the same or similar brightnes as a tone at 10 khz at the same level but I'm not sure. Similar to a VCA compressor that converts a music signal to a fluctuating DC level to control the VCA level.
awesome video thanks
amazing！
Fabulous explanation, Brad! Thank you!!
Glad it was helpful!
thank you for this fantastic video
I've got a bogen/tech-craft TCC-200 that I can find absolutely no info on at all, they've got these mic preamp cards with a 'raysistor' that is a small crystal sized optical cell, weird little thing but it sounds pretty great all things considered
also 9:45 I wish you'd done a null test!
Pretty sure it would have not nulled based on the sound difference and the varying response time of the optical elements.
@@biasedaudio no of course not but it'd def be neat to hear the delta ngl
Very great, thank you
I now want a light thing to watch when I listen to music lol
excellent video, tons of amazing info!
Glad you enjoyed it!
THANK YOU.
You're welcome!
Hm... This thing does make me wonder. Very quick photosensors have been around for audio playback on films for a very long time. As they output the recorded sound from the film they need to be able to work in thousands of a second of time.
Maybe these sensors were deliberately chosen for this compressor because the attack and release of those particular sensors would suit a compressor. As in, not because they were quickest possible but instead because they were a bit slower. It doesn't have to reproduce the frequencies. Just control a fader according to the peaks and valleys of the overall soundwave.
Actually I looked at this closely before posting this video. For film sound a light sensitive vacuum tube was used. I had thought a photo resistor was used but I couldn't find any case as the slow release limits bandwidth.
@@biasedaudio
Ah. Slightly different technology then. Thanks for that detail!
#exciterLamp
interesting stuff!
who else is here for that tightly executed groove!!!
What are the properties of the transformer to drive the EL panel ... and what kind of substitutes are available today and be equal to the old days.
a German made transformer by Block?
i tried a experiments with a simple old rusty 220 Volt to 9 Volt transformer hooked in reverse to my modular synthesizer via a simple 2SC945 transistor and connected a VCO to the base of the transistor and measured something like 200 V, i had to place 1k on the collector sourcing from the power rail, higher values where not good, having the scope on 50 volt per division, covering 4 divisions.
Does Würth have something in their catalog that could serve? these yellow things you find on pcb's.
The EL panel needs something like 110 V, did you measure.
Not sure. It's a stepup. Not sure of the impedance or ratio. I would venture a guess if about 4:1 or 5:1
@@biasedaudio i might have found something, not very expensive, but i gotta buy several models too see and find out. ratios of 1:50, 1:100, 1:200 and multiple windings. pretty small. it's just you don't know the requisitions from the original designers.
Fantastic video as always.
Did you compare to others LA3 plugins. I’ve been using the Apogee and finding it super!
Thank You Alan! I didn't compare to other. Might in a future episodes. Always wanted to do a series of real gear vs plugins. I will take a look at the apogee stuff. Thank You again.
i can hear the 3 differences
through my EL CHEAPO
chinese bLuTeeth
PA speaker .
it does have a
15 inch woofer .
This is so cool! Can you do one on the LA-2 or 2A? like explain how the tubes are involved. Is it the make up gain stage or the output? and then compare it to the UAD LA-2 or 2A. They have the spark plugs now that you can run natively if you don't have an Apollo
Brandon I would if I had some more time but due to the similarities between the la3a and the LA 2A I doubt I'll get around to it. They're almost identical in the LA 2A of vacuum tube is used as the makeup game instead of transistors in the la3a and the only other real difference is the la3a has an interstage transformer to increase the voltage to the electroluminescent panel.
opto compressor masterclass
dope
Okay. This is very good stuff. BUT!! when I look up electroluminescence I can’t find the history of it. You’re talking about a light source faster than incandescent but older than LED tech. So… pleeeeeease elaborate because I can’t find it anywhere and I was hoping I would find it here. Anyone can answer this question. Thank you.
Also, who in their right mind wouldn’t design something that showed off visible light operation? I suppose because outside light could interfere. But I still want to know how pre LED EL worked. Or at least what it was made of.
I googled electroluminescent panel and came up with tons of information and they are still sold. One reference I found says they were invented in 1958.
en.wikipedia.org/wiki/Electroluminescent_display
aopa.org/news-and-media/all-news/2018/october/09/aircraft-maintenance-electroluminescent-panel-repair
patents.google.com/patent/US3306770
Why is the T4B encapsulated if it works perfectly fine without the metal capsule? This is a very introspective video. I would love to see how the T4B works with a iPhone 11+ recording (because it's thin enough to fit inside the LA-3A and records in low light very sharp) while the cover is placed on LA-3A cover is placed on top. While the Pro Tools session is screen recorded and the meters are being recorded simultaneously by another camera on the outside. Then We can see how all of it works together in real time.😁
The T4 is incapsulated to first keep light out, I turned off all the light to shoot this video. Not practical in a studio environment ! also for audio shielding I would guess.
Subscribed! Great video
Awesome, thank you!
people usually explain that the curve for opto compressor is kind of S shaped.
So that is not true?
Well I haven't tested and looked for that. I went with the UREI measured curve. In the days that this unit was released 3 to 6 to compression was a more normal way to operate. I remember being taught back in the day if you compressed more than 6 db you should reduce you preamp gain . 10 dB was considered a lot of compression. In the 80's it became more common to really smash stuff with compressors. As well with the advent of digital compressors with few artifacts heavy limiting has become more common. Under those circumstances I'll assume the Light will hit max brightness or photo resistor will become saturated. I even looked online and viewing the "S" shaped charts where the gain reduction starts to tilt up is in the range of 20 dB of gain reduction. So I'll assume the term s shaped is accurate but only under extreme circumstances. Not really sure of what the advantage of hitting the top of the "S" in the curve would be.
Tele definitely sounded better
Using plugins will make all compressors become FET as computer using billions of transistors inside, not talking about digitizing it. Use an actual and real compressors as possible if you want to experience the real ones.