Congratulations
George, it is people like you that advance the audio arts! Sometimes advances are made by lweaps and bounds and at other times, by small steps. When you think of using light to change the resistor values to change volume or balance, then the field is wide open to use your findings to alter resistance and control circuits in so many other fields. George, for some of us it is so hard to see the forest for the trees! So again, congratulations....I wonder how many other "new technological developments" are out there just waiting "to be discovered".
George, it is people like you that advance the audio arts! Sometimes advances are made by lweaps and bounds and at other times, by small steps. When you think of using light to change the resistor values to change volume or balance, then the field is wide open to use your findings to alter resistance and control circuits in so many other fields. George, for some of us it is so hard to see the forest for the trees! So again, congratulations....I wonder how many other "new technological developments" are out there just waiting "to be discovered".
Thanks JJ, it makes me feel good when I hear thanks and appreciation such as yours.
I never imagined the success Lightspeed Attenuator would have, especially amongst the glitz and glamour hi-end audiophiles, some of them are finally listening and forgetting that it's not the dollar value that makes things sound good. I believe that Sam Telling from Stereophile has had a lot to do with making people aware of it and how it sounds for a paltry $450 compared to other mega $K preamps. Though I am getting a lot of indirect flack from the companies that do build hi-end pre-amps. It is eating into their profit margin, and maybe their conscience that there is really no need for their pre-amps in today's systems.
Cheers George
I never imagined the success Lightspeed Attenuator would have, especially amongst the glitz and glamour hi-end audiophiles, some of them are finally listening and forgetting that it's not the dollar value that makes things sound good. I believe that Sam Telling from Stereophile has had a lot to do with making people aware of it and how it sounds for a paltry $450 compared to other mega $K preamps. Though I am getting a lot of indirect flack from the companies that do build hi-end pre-amps. It is eating into their profit margin, and maybe their conscience that there is really no need for their pre-amps in today's systems.
Cheers George
It is sad that you're getting grief George but that's what happens when something comes along to cause a paradigm-shift. Remember what happened when Nelson introduced the Aleph amplifiers? Simple, accurate, musical yet uncolored for not a lot of $$$.
What you have created is an attenuator that neither adds nor subtracts from the source signal. The only requirement is that the user do some impedance matching between components.
Manufacturers of ultra-expensive preamps needn't worry; their products will always have a market just as Bentleys will always find buyers. Manufacturers of mid-priced preamps (however) should be very worried as you no longer need to spend 2k to get a sonically neutral preamp.
What you have created is an attenuator that neither adds nor subtracts from the source signal. The only requirement is that the user do some impedance matching between components.
Manufacturers of ultra-expensive preamps needn't worry; their products will always have a market just as Bentleys will always find buyers. Manufacturers of mid-priced preamps (however) should be very worried as you no longer need to spend 2k to get a sonically neutral preamp.
I did ldr's 31 years ago, in a home built ARC sp6a clone. I used some tektronix ldr's that were used in the tek 465 oscilloscope (I worked for them at the time). I used two 50k metal film resistors, with the ldr just shunting the second one to ground.
I used a daven 22 position switch, with hand picked resistors to vary the voltage to the ldr's. Also, the daven switch controlled 22 led's placed around the volume knob. I also had touch control volume available, via up/down ttl counters driving a 6 bit dac.
Sounded excellent, was built on two chassis in an old tek 465 rack mount chassis. Had fun smoking the best CJ's of the day at a local high end shop back then.
Brian
I used a daven 22 position switch, with hand picked resistors to vary the voltage to the ldr's. Also, the daven switch controlled 22 led's placed around the volume knob. I also had touch control volume available, via up/down ttl counters driving a 6 bit dac.
Sounded excellent, was built on two chassis in an old tek 465 rack mount chassis. Had fun smoking the best CJ's of the day at a local high end shop back then.
Brian
Sorry
Brian toped you by just 5 years. 1974 the year the Sugden P51 C51 came out, I bought them and was so discussed in the C51 pre I built my first Mk1 Lightspeed Attenuator (series resistor shunt LDR).
Made out of old Lieca camera lightmeter cells, as I was a camera tech back then, boy did they not track too well, and were massive in size
Cheers George
Brian toped you by just 5 years. 1974 the year the Sugden P51 C51 came out, I bought them and was so discussed in the C51 pre I built my first Mk1 Lightspeed Attenuator (series resistor shunt LDR). Made out of old Lieca camera lightmeter cells, as I was a camera tech back then, boy did they not track too well, and were massive in size
Cheers George
Use the LDR as remote
LDR have been popular devices in equipment for musicians for many many years. Specially when musician need to control parameters on effects from remote location LDR have come in handy.
On that thought, are there anyone here that have tried to move the LDR's to the input connector on the power-amp?
LDR have been popular devices in equipment for musicians for many many years. Specially when musician need to control parameters on effects from remote location LDR have come in handy.
On that thought, are there anyone here that have tried to move the LDR's to the input connector on the power-amp?
Yes and it is worth the effort to move them to the inside of the amp, even to on the amp board if you can. Build a tiny little perf board with the LDRs on it then just put it on the inputs of the amp module and there is a very nice improvement. Removes a whole set of RCA cables
Uriah
Uriah
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Inside the amp is not a good idea as they(the LDR's) are temperature sensitive if not in a controled environment, and the the temperature inside an amp is far form being a stable temperature controled environment, you will get drift all over the place, this is why in the production Lightspeed Attenuator they are potted all together in a stable temperature environment.
Cheers George
Cheers George
Class D (yuck) may just be alright if they have vent holes, but any linear solid state even with SMP power supplies Class A/B or Class A should be avoided, and especially tubes amps. As a temp variation of just a few degrees in a short time will cause inter-channel drift, even if potted.
Cheers George
Cheers George
I agree. I think we both know how high resistances are changed by a few degrees. If you use the LDRs down below 8k -10k the temp drift is so minimal that I dont have a problem with putting them in an amp. However if I was using the LDRs as a 10k pot or higher they would be changed to much by temp for my taste. Even if it was not audible. I think that at 15k-25k it would be much more audible.
My taste in sound is different than some of course and I really like to run the LDRs down at 6k into my ClassD (yum ) as the transparency is so unbelievably good in that region.
Guys if you want some of that tubey flavor to your sound just try running your LDRs at around 22k Rtot.
Uriah
My taste in sound is different than some of course and I really like to run the LDRs down at 6k into my ClassD (yum
) as the transparency is so unbelievably good in that region. Guys if you want some of that tubey flavor to your sound just try running your LDRs at around 22k Rtot.
Uriah
I haven't commented in this thread before, but the LED as a light source caught my attention, and there are many properties of LEDs as a light source that should be known and considered. I did a search on the thread and found where LED aging was mentioned, but I've heard of other possible problems with LEDs that may not have been discussed. The alternative would be a small tungsten-filament incandescent light bulb, though a bulb would have its own problems. For one, you would likely need active circuitry (one or more transistors) to drive the filament, as it's surely a bad idea to put that much current through a typical potentiometer.
Two more problems with LEDs mentioned in the link below (it's from a mailing list, some is plain text, some is HTML that doesn't render from the .txt archive file) are changes in light output with temperature, and noise in LED light output (the "inherent photon noise levels"). The application (Seismographs) requires a steady light source going to a photodiode varyingly interrupted by a vane on a moving element that varies the light the photodiode receives with its position.
Recent posts mention temperature sensitivity of LDR's. This could be a problem using an incandescent light for volume control, unless the light and LDR are sufficiently thermally separated. It's not a problem in seismometers (even though photodiodes may be temperature sensitive), as the light is always on at the same constant power level continuously, and the temperature eventually stabilizes.
http://psn.quake.net/info/psnl01q4.txt
The relevant text has some content unrelated to an LDR attentuator, but I've included it all here for context:
Two more problems with LEDs mentioned in the link below (it's from a mailing list, some is plain text, some is HTML that doesn't render from the .txt archive file) are changes in light output with temperature, and noise in LED light output (the "inherent photon noise levels"). The application (Seismographs) requires a steady light source going to a photodiode varyingly interrupted by a vane on a moving element that varies the light the photodiode receives with its position.
Recent posts mention temperature sensitivity of LDR's. This could be a problem using an incandescent light for volume control, unless the light and LDR are sufficiently thermally separated. It's not a problem in seismometers (even though photodiodes may be temperature sensitive), as the light is always on at the same constant power level continuously, and the temperature eventually stabilizes.
http://psn.quake.net/info/psnl01q4.txt
The relevant text has some content unrelated to an LDR attentuator, but I've included it all here for context:
You will be surprised how nice the NCD works with this kind of volume control. The majority of speaker have more problems than you can imagine.
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could you explain what 10k and 15k-25k and 6k and 22k Rtot are referring to?