"I swear the LED made my whole system sound "sterile" and "sublime".......I know this because I just had my ear drum calibrated by Ben Dover, whom was highly recommended by John Atkinson, editor of Stereophile. He shifted my ear wax back into the more linear portion of it's wax curve, now I can hear the openness/pedantic change these LED's make to my SEP (single ended pentode(no feedback)) amplifier. My wife whom was making a fantastic snake oil glaze noticed the difference from the other room."
-me
-me
Thanks for all the responses. I thought the graph for LED's and their forward voltages would be very helpful. The only problem is that when I look up the LED's the voltages don't match those in the chart. In fact they seem to be higher across the board.
I gave up on graphs and charts - now I put in my best guess colour LED then measure then adjust. Saves brain strain.
So… we are right back to the advice I offered in another thread: measure your LED forward voltages, across a handful of LEDs! Use a 9V battery, a 100Ω (1%) resistor and a 5KΩ pot all in series with the LED. Use a cheap digital meter to measure voltage across the 100Ω resistor … to determine pretty accurate current flow. Without changing rheostat, measure voltage across it. 2 points. Change the brightness. Repeat measurements. Repeat cycle until you build up 10 or so data pairs. Use EXCEL to keep track of data and to plot it if you like.
Now you have highly calibrated, entirely arbitrary value LEDs. Need a particular voltage-current combo? Those little graphs will help you find exactly the right LED, on the first try. Oh yah… if a bunch of them (typically from same purchase-lot) have the same general curve, then keep 'em in the same ziplock bag.
Why this is so opaque to most people, is beyond me. … I've seen people go to great lengths to purchase something supposedly magical, when in fact, using the remarkably precise el-cheapo Radio Shack DVMs, one could easily buy a bunch of stuff, and measure it all to 0.25% precision. You can not buy 0.25% precision LEDs (in forward voltage and/or current flow)
GoatGuy
People these days seem to need to be told what they should like, and what they should use. So if someone tells you to use BloggsTech XYZ1256 LED for good sound you know you are in good company. You can be sure you have good sound (by, if necessary, redefining 'good sound' to mean whatever you get with that particular batch of components) even if BlogsTech have changed the process or done some badge engineering.GoatGuy said:
So, you can build and use an SRPP (everyone uses SRPP, don't they?) without having to learn how to use a DMM and Ohm's Law. Someone will tell you what resistor value to use, and everyone knows that big coupling caps are better than small coupling caps.
I have been reading this site for … well, a long time. I finally took the plunge and "signed up" about 3 years ago or something like that. Mostly because I thought some of the ridiculous ideas needed to be countered with rationale and right reason. I've not been authoring many rebuttals of late: it seems like there's an irrational “group-think” that simply will not go away, even when quantitatively countered. Or, like trying to fight a swarm of mosquitoes with a butterfly net.
However, I come back for comments like yours. Thank you, DF96.
Just yesterday, I was privately contrasting 2 friends, who've come to me (in the flesh), with schematics which they asked me to both explain, and to comment on critically. On fellow … is a magic unicorn powder type, the other is a career scientist entering his golden years, wishing to take up DIY audiophile noodling. Both … with about the same amount of electronics sussing knowledge.
What a difference. I could easily explain the intricacies of a fairly complex circuit to the scientist; easily define how (in this case) transistor non-linearity is tamed by use of voltage dividers, degenerate emitter 'negative' feedback, and so on. It was … refreshing. In a few hours, he's now armed with 20 "engineering patterns" which he can use to decode most-any circuit. Some time back, the magic unicorn powder guy, who is endlessly knowledgeable about the esquisite soundstage enhancing qualities of black tung oil capacitors, charred beansprout resistors, hyperfilar transformers with cobalt cores and bicubic boron nitride magnetic pickup needles … basically, I couldn't explain anything at all, past the compendium of ritual chants, spells and ghost-wards that he had enshrined in his mind.
Cargo cult?
Maybe in the end, that is the answer: some people simply want to believe that there really is perfection beyond the numbers, perfection that one might actually be able to see in the exotic purpleheart case and ultraviolet laser etched beryllium-copper top-plate of the amplifier in question. Never mind that one's listening to recordings made in the 1960s, when nothing at all was of much quality. Nope. Its about the journey, not the destination.
I despaired. I continue to dispair. I will undoubtedly be dispairing for some time to come.
GoatGuy
Rather too many threads on here start with something like "I intend to change all the electrolytics (or resistors or opamps) in this (perfectly ordinary but competent commercial) piece of audio equipment, in order to upgrade it. Does it matter if I use the same values or not? By the way, what function does each electrolytic (or resistor or opamp) perform in this circuit? I have been told that WalletLift brand are the best to use for audio."
All we can do is to be generous with our patience (and time), and try to give them single pieces of advice. “Oh, you really shouldn't change the values, son. Your soundstage could be drastically shortened, and the air and breadth of the midrange could be squashed into a quantum dot.”
We'd be believed. We'd have injected new virus-memes into the compendium of ritual chants and ghost wards. The witch doctors, caught off guard, would rapidly take up the new riff, and run it up the flagpole. We, not laughing all the way to the bank, would at least have a laugh or two. “Hep, I coined the word Framistat, sonny”
GoatGuy
This thread illustrates perfectly why I run screaming when I hear the line: "I am an audiophile and what do you think about xxx."
Thanks for a good laugh.
By the way I am a big fan of LED bias and I don't worry too much about their tolerances. (The tubes generally are way worse.. lol)
Thanks for a good laugh.
By the way I am a big fan of LED bias and I don't worry too much about their tolerances. (The tubes generally are way worse.. lol)
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