Hmmm... I think linearity is much more important than contact... but I'll prefer ears to decide. At least I know where difference might come from, in case there is any difference between them...
I forgot if there was or not a discussion regarding why the resistors in LDR are supposed to be better than resistors in stepped attenuator?
(A) The quality of the series resistors?
(B) The quality of the contact?
I forgot beside
There is also a (C) to your list Jay, that is related to (A) the fact that the ldr series resistor is neither metal film, carbon, or conductive plastic all of which sound different to each other.
The LDR conductor is Cadmium Sulphide which could be the reason why so many like it's sound, over the others.
Cheers George
Correct and 20mA is around the max, any more and you run the risk of cooking them over time, or blowing them almost straight away if grossly unmatched.
Which to me is a worry for the all auto calibration circuits that are around to force match unmatched ldr's.
If they do not have a safeguard of 20mA max they could force the ldr into overload. And also have a too high listening level lowest volume level.
Cheers George
LDRs do have a linear impedance up at least to 20k according to my AP.
Current limiting is easily employed with a resistor.
LDRs just sound fantastic as a replacement for other resistive elements. They are great as input resistors and even in feedback loops but caution on feedback loops as a dead ldr in a feedback loop could be bad news.
I agree with George. I think its the cadmium sulphide that sound so good. Ive gone from .8% to .01 and lower in THD and dont hear a very meanigful difference or a lack of that great transparency and smoothness so while its just an assumption I assume its not the THD giving the great sound.
Current limiting is easily employed with a resistor.
LDRs just sound fantastic as a replacement for other resistive elements. They are great as input resistors and even in feedback loops but caution on feedback loops as a dead ldr in a feedback loop could be bad news.
I agree with George. I think its the cadmium sulphide that sound so good. Ive gone from .8% to .01 and lower in THD and dont hear a very meanigful difference or a lack of that great transparency and smoothness so while its just an assumption I assume its not the THD giving the great sound.
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No maybe not the Key point, as I said "could be the reason"
But I lean more to the "diode effect" that potentiometers may have especially when they have a bit of wear, between two the dissimilar very light contact materials with a (brass wiper with conductive track) and the signal current that has to flow between them.
Whatever it is, out of the three differences the LDR just sounds better, even against a switched resistor VC.
Cheers George
It's the key point for me. Because I couldn't understand how the other variables could make a big difference [but bias could].
I can't say for sure but also say it a combination of all three that makes it special.
This is a very basic explanation of the "Diode Effect"
The screw can be the input of a volume pot, the whisker the wiper and the razor blade the conductive track output of a pot.
Electronics Projects - Components - Capacitors
Cheers George
Do you still have these available? If so I would like to grab a stereo set from you.
Cheers,
Tim
I have found myself a set of udaileys matched LDRs.
Can someone advise me as to how I should select them in the circuit.
From the attached image should I use one from each pair for the the left and right series LDR and the remaining 2 for the shuntsas the image below? Or have I completely misunderstood this.
Thanks,
Kffern
Can someone advise me as to how I should select them in the circuit.
From the attached image should I use one from each pair for the the left and right series LDR and the remaining 2 for the shuntsas the image below? Or have I completely misunderstood this.
Thanks,
Kffern
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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Hi Peter, you can get them in Hong Kong get the $5 led tester I posted in the 1st post of this thread. Get a friend and yourself to buy 20 pieces from here, you'll get enough for two quad matched sets and sell the left overs ones.
Hong Kong Nsl-32sr2s, Hong Kong Nsl-32sr2s Manufacturers and Suppliers on Alibaba.com
Cheers George
Hong Kong Nsl-32sr2s, Hong Kong Nsl-32sr2s Manufacturers and Suppliers on Alibaba.com
Cheers George
Hi George,
I followed the link you supplied for the LDR's but they didn't have any in stock.
I managed to locate a different supplier but the model number is slightly different. Are they still suitable?
NSL-32SR2. - ADVANCED PHOTONIX - OPTOCOUPLER, RESISTIVE O/P | element14 Australia
Appreciate your assistance,
Cheers,
Tim
Yes Tim, they won't be as close to each other as the "S" version, so get another ten to get quad matching, you'll probably end up with 2 x quad matched sets so you could sell one set here.
Also the "S" version is typical 40ohms (on resistance) @20mA, so the "S" gives better attenuation at minimum level.
Where the "non S" does not specify (on resistance) @20mA, and can be a bit of pot luck, minimum level could be a bit loud for background music.
Cheers George
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