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Was looking around at passive limiters and such, and came across an interesting implementation in “Lamplifier Microphones”. ?From what I can gather, the microphone has an internal preamp that lights a small incandescent bulb. Said bulb, as it starts to glow, becomes higher resistance to signal, functioning as a form of audio compression.
Just seemed clever in its simplicity. ?Don’t know how it sounds though.. ?The website Lamplifier.com seems to be defunct and their contract info email box is full. ?That might give me my verdict right there. ?
?Thought it might be fun to try with a tiny “grain-of wheat “ bulb..
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... Said bulb, as it starts to glow, becomes higher resistance to signal, functioning as a form of audio compression...
Probably a Vactrol optically-controlled variable resistance.? Like:
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No. They use small incandescent light bulbs.
This type of passive limiter requires substantial level to
operate. The signal from a microphone is too weak, so it must be
amplified. That means there should be a battery in the mic, which
is quite inconvenient.
Le 13/04/2022 à 02:38, Tom Becker a
écrit?:
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... Said bulb, as it starts to glow, becomes higher
resistance to signal, functioning as a form of audio
compression...
Probably a Vactrol optically-controlled variable resistance.?
Like:
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This technique reminded me of the same thing that was employed in Hammond organs, back in the day (1960s/70s). They used light bulbs to 'limit' the drive to the inductive drivers on the spring reverb units.? They were connected to the output of a power amp, and included the bulbs in the signal path itself. As Jerry has already commented, using an audio signal to light an incandescent bulb requires a fair amount of power !? ?? The assembly in the sketch below was connected to the output of the reverb audio amp, so the 'sig. input' would normally have been a loudspeaker.... It used to alarm some customers that they could see an intermittent 'glow' under an amp chassis, when the service tech had the back off the instrument! :) 
On Tue, Apr 12, 2022 at 11:12 PM, M H wrote:
Was looking around at passive limiters and such, and came across an interesting implementation in “Lamplifier Microphones”. ?From what I can gather, the microphone has an internal preamp that lights a small incandescent bulb. Said bulb, as it starts to glow, becomes higher resistance to signal, functioning as a form of audio compression.
Just seemed clever in its simplicity. ?Don’t know how it sounds though.. ?The website Lamplifier.com seems to be defunct and their contract info email box is full. ?That might give me my verdict right there. ?
?Thought it might be fun to try with a tiny “grain-of wheat “ bulb..
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FWIW:
I still use that technique to protect tweeters in DJ speakers... Op wo 13 apr. 2022 om 11:34 schreef Arjay 1949 < info@...>:
This technique reminded me of the same thing that was employed in Hammond organs, back in the day (1960s/70s).
They used light bulbs to 'limit' the drive to the inductive drivers on the spring reverb units.?
They were connected to the output of a power amp, and included the bulbs in the signal path itself.
As Jerry has already commented, using an audio signal to light an incandescent bulb requires a fair amount of power !? ??
The assembly in the sketch below was connected to the output of the reverb audio amp, so the 'sig. input' would normally have been a loudspeaker....
It used to alarm some customers that they could see an intermittent 'glow' under an amp chassis, when the service tech had the back off the instrument! :)
On Tue, Apr 12, 2022 at 11:12 PM, M H wrote:
Was looking around at passive limiters and such, and came across an interesting implementation in “Lamplifier Microphones”.? From what I can gather, the microphone has an internal preamp that lights a small incandescent bulb. Said bulb, as it starts to glow, becomes higher resistance to signal, functioning as a form of audio compression.
Just seemed clever in its simplicity.? Don’t know how it sounds though..? The website Lamplifier.com seems to be defunct and their contract info email box is full.? That might give me my verdict right there. ?
?Thought it might be fun to try with a tiny “grain-of wheat “ bulb..
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Would this technique not introduce a LOT of noise?
On the marketing side of things though it is a treasure chest: one could tune and sell lamps for different pre-sets of compression ratio, attack and release. And then charge extra for the sets of balanced lamps for stereo recording!
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Le 13/04/2022 à 16:16, Dibutil Ftalat a écrit?: Would this technique not introduce a LOT of noise? Why would it?
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I think that might depend on where this is introduced into the signal path...
In the case of the Hammond circuit I posted above, the incandescent bulbs were fitted as two legs of the 'bridge' fitted across the amplifier output.
So no following gain stages, and no noise from the additional 'variable' resistors that the bulbs essentially were.
I don't think this type of compressor has much application at the mic preamp part of the signal path.?
3 main reasons:
? They need considerable audio power to function
? They're slow, so don't catch transients well.
? The attack and release times are essentially fixed, and are determined by the bulb characteristics?
As Wim has posted above though, they do still have some useful applications...
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On Wed, Apr 13, 2022 at 03:16 PM, Dibutil Ftalat wrote:
Would this technique not introduce a LOT of noise?
On the marketing side of things though it is a treasure chest: one could tune and sell lamps for different pre-sets of compression ratio, attack and release. And then charge extra for the sets of balanced lamps for stereo recording!
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Here is the patent if anyone is interested.
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Such a strange combination of uC, ASP/DSP and outdated tech.
Seems ludicrous to me. I believe the absence of commercial success
attests it.
It will probably go in the gallery of irrealistic inventions with
the GPS wheelbarrow and the computer-controlled candle stick.
This guy probably spent a fortune in legal fees. Someone should
have told him his best protection was the unattractiveness of his
invention.
Le 14/04/2022 à 05:16, M H a écrit?:
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Here is the patent if anyone is interested.
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Buggy whip with 56k modem, and tape backup..
I my very very humble opinion, I agree. ?Think “simpler” would have been better (again, my opinion). ?Maybe the inventor had some goals in mind that I wouldn’t have, don’t know. ?He also co-invented the “Sustainiac”, which I find to be a fun gadget.
Still think I might try it with a tiny 1.5v GOW/GOR bulb, under-driven by phantom (and buck converter or something?) modulated by a dynamic or piezo. ?Maybe make it a stand alone effect instead of “in mic effect”. ? Just a fun experiment..
I would have been very curious had I seen my dad’s Leslie speaker cabinet glow more with the reverb! ?(I LOVED the reverb, and everything else about it and the Hammonds he had - except having to move them for gigs!)
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Hi, I am sorry, maybe I do not understand an idea but, I found something what may replace lamps: Vishay?
VO1263.? Here is a link to the Mr?Scott Wurcer article (diyaudio Forum): "My
version of the G = 1000 low noise measurement amp" Andrzej
Buggy whip with 56k modem, and tape backup..
I my very very humble opinion, I agree.? Think “simpler” would have been better (again, my opinion).? Maybe the inventor had some goals in mind that I wouldn’t have, don’t know.? He also co-invented the “Sustainiac”, which I find to be a fun gadget.
Still think I might try it with a tiny 1.5v GOW/GOR bulb, under-driven by phantom (and buck converter or something?) modulated by a dynamic or piezo.? Maybe make it a stand alone effect instead of “in mic effect”. ? Just a fun experiment..
I would have been very curious had I seen my dad’s Leslie speaker cabinet glow more with the reverb! ?(I LOVED the reverb, and everything else about it and the Hammonds he had - except having to move them for gigs!)
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I believe the only thing this circuit has in common with the
subject discussed here is that they both are related to
electronics.
Le 15/04/2022 à 08:04, Andrzej Sochon a
écrit?:
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Hi,
I am sorry, maybe I do not understand an idea but, I found
something what may replace lamps: Vishay?
VO1263.?
Here is a link to the Mr?Scott Wurcer article
(diyaudio Forum): "My
version of the G = 1000 low noise measurement amp"
Andrzej
Buggy
whip with 56k modem, and tape backup..
I my very very humble opinion, I agree.? Think “simpler” would
have been better (again, my opinion).? Maybe the inventor had
some goals in mind that I wouldn’t have, don’t know.? He also
co-invented the “Sustainiac”, which I find to be a fun gadget.
Still think I might try it with a tiny 1.5v GOW/GOR bulb,
under-driven by phantom (and buck converter or something?)
modulated by a dynamic or piezo.? Maybe make it a stand alone
effect instead of “in mic effect”. ? Just a fun experiment..
I would have been very curious had I seen my dad’s Leslie
speaker cabinet glow more with the reverb! ?(I LOVED the
reverb, and everything else about it and the Hammonds he had -
except having to move them for gigs!)
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> .. both are related to
electronics...
Yes, OT but related, Heathkit once produced a mod to the "Two-er" (and "CB1", "Ten-er" and "Six-er") which uses a Wheatstone bridge composed of two #47 bulbs and two 4.7Ohm resistors to yield a squelch that quiets the receiver's inherent super-regenerative hiss when no signal is tuned.
Tom
On Saturday, April 16, 2022, 6:51:40 AM EDT, Jerry Lee Marcel <jerryleemarcel@...> wrote:
I believe the only thing this circuit has in common with the
subject discussed here is that they both are related to
electronics.
Le 15/04/2022 à 08:04, Andrzej Sochon a
écrit?:
Hi,
I am sorry, maybe I do not understand an idea but, I found
something what may replace lamps: Vishay?
VO1263.?
Here is a link to the Mr?Scott Wurcer article
(diyaudio Forum): "My
version of the G = 1000 low noise measurement amp"
Andrzej
Buggy
whip with 56k modem, and tape backup..
I my very very humble opinion, I agree.? Think “simpler” would
have been better (again, my opinion).? Maybe the inventor had
some goals in mind that I wouldn’t have, don’t know.? He also
co-invented the “Sustainiac”, which I find to be a fun gadget.
Still think I might try it with a tiny 1.5v GOW/GOR bulb,
under-driven by phantom (and buck converter or something?)
modulated by a dynamic or piezo.? Maybe make it a stand alone
effect instead of “in mic effect”. ? Just a fun experiment..
I would have been very curious had I seen my dad’s Leslie
speaker cabinet glow more with the reverb! ?(I LOVED the
reverb, and everything else about it and the Hammonds he had -
except having to move them for gigs!)
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Dibutil Ftalat
Andrzej Sochon