Is there any reason why, if wanting to use different output tubes, such as my namesake 6L6, the LED string can't be made a bit longer? I.E., if you wanted the cathodes at 18V, just use 10LED x6 or x7. 
Would not the array be able to dissipate more current due to the extra devices? Or, are there any other LED devices that would work better than a metric clown-ton of cheap red ones?
Oh, for those who don't know, the pronunciation of Bevois =
Would not the array be able to dissipate more current due to the extra devices? Or, are there any other LED devices that would work better than a metric clown-ton of cheap red ones?
Oh, for those who don't know, the pronunciation of Bevois =
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Or like the Beavis in Beavis and Butthead.
Yes, you can absolutely make the strings longer. You want to make sure that you're not pulling more than 20-25mA out of each string. I think that high intensity white LEDs (like they use in lightbulbs) could also work very well, and they can take some serious current.
Yes, you can absolutely make the strings longer. You want to make sure that you're not pulling more than 20-25mA out of each string. I think that high intensity white LEDs (like they use in lightbulbs) could also work very well, and they can take some serious current.
LED lamps - I like that... Although it's going to be heart of the sun bright...
Should the series resistor be included in each string? (To be honest, reading that part a million times, I still don't get what the 4R7 resistors are doing... the 1R for measuring plate current, sure, but the others,)
Should the series resistor be included in each string? (To be honest, reading that part a million times, I still don't get what the 4R7 resistors are doing... the 1R for measuring plate current, sure, but the others,
)
I'm not sure if this was covered earlier in the thread but is there a reason you didn't use LEDs to bias the input or phase splitter?
I have been looking for alternatives to wiring up 36 leds X 2 for the RLD. Am I wrong in thinking that a large LED like thisLZ4-40R208-0000 LED Engin | Mouser could replace the 36 leds used for output biasing in a single package?
I'm also curious if you have considered designing a big brother for the RLD? Maybe something using GU50 or KT88 and putting out 50+watts?
I have been looking for alternatives to wiring up 36 leds X 2 for the RLD. Am I wrong in thinking that a large LED like thisLZ4-40R208-0000 LED Engin | Mouser could replace the 36 leds used for output biasing in a single package?
I'm also curious if you have considered designing a big brother for the RLD? Maybe something using GU50 or KT88 and putting out 50+watts?
I've been interested in subbing one of the white LED arrays, but time has not been kind to me of late. They do require some attention to mounting and heatsinking, and someone will need to measure their AC impedance to determine suitability.
The phase splitter is self biased by definition, so doesn't need any sort of extra parts. The input stage, in theory, could be LED biased, with a small resistor on the bottom for the feedback loop (the feedback resistor would also have to be scaled down proportionately for the correct gain). There could even be a minor distortion advantage since this would increase the open loop gain a bit. Minor, though. But if you want to play with it, I'd be very interested in your results!
They do require some attention to mounting and heatsinking, and someone will need to measure their AC impedance to determine suitability.The phase splitter is self biased by definition, so doesn't need any sort of extra parts. The input stage, in theory, could be LED biased, with a small resistor on the bottom for the feedback loop (the feedback resistor would also have to be scaled down proportionately for the correct gain). There could even be a minor distortion advantage since this would increase the open loop gain a bit. Minor, though. But if you want to play with it, I'd be very interested in your results!
I'm (slowly) working on that -- Push Pull Parallel EL84, should be good for 35W or so...
Look for led arrays geared toward the saltwater aquarium trade... I have used various ones for LED biasing with great success on output tubes. Look at Cree XM-L, XT-E and Philips Luxeon M series, or Bridgelux BXRA. LEDGroupbuy.com, and StevesLEDS.com are where I have ordered from in the past. I have a 72w LED array over my Reef tank, and have been playing with them for biasing for a while. I have a red LED 10w multichip for a pair of 6V6 that sits at about 16v, and at full tilt only goes up by about 20mv.
Here is a pic of my White Light District... 12av5ga output tubes and the front end is from the Red Light District...
My camera FREAKED OUT with the amp powered up and the white light running... But with this particular LED running it sits at 27.5v... Voltage doubler PSU, unregulated at all. My B+ is at 365v, screens connected to the center tap of the doubler, so they are sitting at 182v... This thing is DEAD SILENT and the tubes draw 33mA each. At full tilt each tube is blowing about 200mA and the LED drob only goes up about 25mV. This is a no-name LED from a chinese shop on ebay, I think it was about 2 bucks. I'm pretty sure this is how I'm biasing my next amp.
My camera FREAKED OUT with the amp powered up and the white light running... But with this particular LED running it sits at 27.5v... Voltage doubler PSU, unregulated at all. My B+ is at 365v, screens connected to the center tap of the doubler, so they are sitting at 182v... This thing is DEAD SILENT and the tubes draw 33mA each. At full tilt each tube is blowing about 200mA and the LED drob only goes up about 25mV. This is a no-name LED from a chinese shop on ebay, I think it was about 2 bucks. I'm pretty sure this is how I'm biasing my next amp.