I am only guessing, but is it not customary to run one production line.. some output from the line are not tested and marked and sold as unsorted. Some subset are 100% tested and then graded as sorted. These would also be the ones that yield better specs.
This was the process with TDA1541a chips in the day as the best yeild got a crown and now sell for 10x the regular. Same with all intel processors. One production line produces a full range of processor speeds. The expensive fast ones are simply the ones that happened to come out better. I have to expect it is the same for these LDRs. I recall that when I ordered mine, I ordered 10 sorted ones hoping for a couple of pairs that match. They came back all ten from the C grade and all yielded 4 pairs with very tight matches. The original problem was that the distributor was not keeping them sorted. You could order 10 sorted and get 10 all with different grades at random. Complaints from this forum corrected that if I recall.
Her er foresten app note fra silonex regarding optcoupler volume control.. (It has probably been linked to before)
Silonex Inc.: Technical Reference: Audio Level Control with Resistive Optocouplers
Silonex Inc.: Technical Reference: Audio Level Control with Resistive Optocouplers
I use 2 LDRs and one stereo pot for the left channel, and the same for the right channel, and a mono switch . Then I regulate the balance by ear. If the center signal comes out right in the middle of the speakers, it´s fine. Back to stereo and voila. It´s a little more work, but I like it. And I wot go back to Pots anymore. And I only match LDR for the lowest Level, I dont match the upper LDRs at all. I use 4 DC sources , one for every LDR. You don´t have to like that, is just an idea I´m using for a couple of years... but the sound... 
Correct, this was Allied Electronics where I first used to get them years ago, they were getting the NSL32SR2S in 1k lots which were baged and batched from Silonex.
But what was happening Allied were topping up their bins not yet empty with with the new stock (not of the same batch).
I got onto this and complained and Silonex sorted Allied out with their problem, not to top up bins with new stock unless they were empty.
Cheers George
WHAT
Well mixed up Norwegian with English
and unable to edit the post now. It says :
"Here is app note from ..........."
Yes, the LDR are so sensitive to the temperature changed, after many tries, I had built one with temperature compensation, I can used any LDR as it can go to 50 ohm or below, I used four pots to adjusted each LDR, I can calibrated it from 5k to 50k ohm ranged. I had put the attenuator on a hot plate, heat up very slow from room temperature to 36.4C and the channel balance changed less than 1db. Set up as: input signal 1 khz 1.5 vrms attenuator=20k
volume set at 12 O'clock. At 20.7C L channel = -7.42db R= -7.84db
at 31.1C L= -6.59db R= -6.80 at 36.4C L= -6.83db R= -7.40db
Attachments
Thats pretty "COOL"!
How do you compensate for temp? Are you using something similar to the temp comp on a LM334 or are you using thermistors in parallel with the control pot? I suppose that would only work in higher resistances.Thats pretty "COOL"!
I am not used ccs or fix 5 volt, my designed was variable the voltage to
the LDR led, I used thermistors to compensated the voltage to the led.
It only need to compensated uv/degree, with variable voltage I can used a switch to changed the output voltage to the LDR's and the resistance will changed, this design the attenuator can had multi resistance value.but I found two is good enough high or low resistance, high/20k for my tube amp,low/10k
for solid state amp.
Yes Mike, for something that has been proven and working for years by those that have bought and made them as I've stated many times. This and many more that have tried to overcomplicate are just proving what the old adage says "if it aint broken, don't fix it".
I have in the past tried also with master of electronics that can put anyone here to shame to make a system that monitors and re-calibrates automatically, it becomes a complex nightmare that in the end detracts from the purity of the sound.
Because the only way to do it right is to monitor the resistance at different volume levels of each and every ldr, this in itself has to be connected to where the music signal is present and creates it own set of problems, like a feedback arrangements can.
BTW my prototype MkII that I use, was made some 8 years ago and is still in balance, and is on most times 24/7
Cheers George
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Quote http://www.diyaudio.com/forums/anal...uator-new-passive-preamp-494.html#post3332786
I thought the issue of plagiarism and in fact posting simply to draw attention to ones own agenda, had been well and truly buried here ? I wondered when someone was going to pick up on this, he’s been riding on the back of this thread for a while now and making money and it’s getting worse
I for one am tired of it. Although I don't contribute a lot here, I read every post with interest, having been a LS owner for more than 6 years. It strikes me as going against almost everything that diyAudio stands for.
Leave this thread alone, unless you have a worthwhile contribution. By all means, promote your LDR's/Product, but on your own thread.
This is purely for discussion of Georges Product, its design and merits. Given the number of posts to date, I'd say it seems quite popular ?
Regards
'Nutz
I thought the issue of plagiarism and in fact posting simply to draw attention to ones own agenda, had been well and truly buried here ? I wondered when someone was going to pick up on this, he’s been riding on the back of this thread for a while now and making money and it’s getting worse
I for one am tired of it. Although I don't contribute a lot here, I read every post with interest, having been a LS owner for more than 6 years. It strikes me as going against almost everything that diyAudio stands for.
Leave this thread alone, unless you have a worthwhile contribution. By all means, promote your LDR's/Product, but on your own thread.
This is purely for discussion of Georges Product, its design and merits. Given the number of posts to date, I'd say it seems quite popular ?
Regards
'Nutz
Woah! Gotta jump in here.
This is not a vendor bazaar thread. Presumably, George started this thread to help DIY build their own LDR attenuator. If he wanted to promote or support his own commercial product (which isn't even DIY, so why would he be here?) then he should have gone to the vendor bazaar. This thread is for DIYers who want to build their own LDR attenuator. George provided the schematics and then said "Hey go get your own parts."
For a long time Uriah was the only source for matched LDRs, although now there are others and we know how to match our own using low cost devices. In contrast to George, Uriah does sell parts and kits to assist DIYers in building an LDR attenuator. In general, he takes commercial traffic off the forum, although some users ask questions about his products here. He typically replies via PM. Uriah does have a signature link to his website, which I consider to be a service, not an annoyance.
Hey, I will promote him: If anybody wants to look at a variety of LDR solutions, including switching and remote control, check out Build An Amp. I am in no way affiliated with Uriah. That is a service to members of this forum and in no way hurts George.
Both Uriah and George are vendors of LDR products and both promote their wares in this forum (Uriah subtly, George not so subtly). Since it is a non-commercial forum, if you think that is violation of DIY Audio rules, then report it. At least Uriah has a DIY product.
Think about this for a second: George makes a commercial product, but he comes on this thread to tell us how to make our own and not buy his product. What's the marketing logic of that? Not exactly an A+ in business school. Perhaps some will decide not to build their own and buy George's product -- there's some marketing strategy in that. Most of us DIYers were not going to buy the commercial product anyway, so we're not hurting George any more than he hurt himself by starting this thread.
I also recall that some suppliers have asked George if it is OK to post in this thread and he long ago gave permission for that. Hats off to George a true friend of the DIY community.
Keep in mind that both George and Uriah have done a great service in assisting us DIYers in constructing and designing our own LDR attenuators. Don't screw it up for the rest of us who gain valuable information from Uriah's posts. Nutz, you Uriah an apology.
Both do this for personal gain and both WAY MORE than return the privilege by helping others in true DIY spirit. Both are honorable individuals.
Woah there sunshine, you got that a little misconscrewed, yes at first I only gave the idea across for diyers so to use their minds a little, then I gave the schematics, but still held back on the brand/location of the LDR's and matching, again to get the diyers to use their minds a little more, then I showed how to match and where to get the components. I learnt this way of teaching from the master (even though he can be an outright pig sometimes) the one and only Jocko Homo (RIP from these forums)
udailey came in years after this, and asked me if I minded him doing matched ldr's for the diyers. I said yes to the matched ldr's only if they are done right, as I do them, and no kit sales or made up units to be sold, and I think it was 10% precentage of the matched ldr sales had to go back to diyaudio as donations.
So now you have the whole story.
Cheers George
Those issues are between you and udailey and none of audionutz' business. Perhaps you didn't know what you were starting up here and how enormously popular your idea would be on DIY Audio. As troystg posted above, both of you have contributed greatly to us DIYers and we are greatful. And as always, you are a gentleman.
That's ok Michael, but get the facts before posting, especially when it's about me. I knew I would be big, how big I didn't know. Because of feedback and interest back in 1979 or whenever it was, everyone was stunned at the sound then compared to preamps but it was about as reliable as an as a drunk in a brewery, Melos found that out in the 90's also.
Cheers George
Cheers George
Oh dear! Implying that making money or that making a (gasp!) profit is somehow untoward, or wrong, is promoting a political agenda (and is most-utterly misguided, in my opinion), which is not tolerated, anywhere on diyaudio. I am profoundly offended by your post. Please, cease and desist from posting anything else with any implied or overt socialist or communist dogma.
