Light Dependant Resistor 3 Input Preamp Kit - Page 2 - diyAudio
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View Poll Results: What is reasonable to pay for a LDR 3 input Kit
$150.00 12 80.00%
$180.00 1 6.67%
$300.00 2 13.33%
Voters: 15. You may not vote on this poll

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Old 29th September 2013, 08:21 AM   #11
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Hi Paul
12 volt battery is fine to use, or a regulated 12 volt plug pack supply. Nice construction !

Cheers / Chris
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Old 30th September 2013, 01:17 AM   #12
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Hi Paul
Have you had a chance to listen to it ? If so can you comment how it compares with other pre amps you might have used.

Cheers / Chris
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Old 30th September 2013, 03:12 AM   #13
tubo is offline tubo  Philippines
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So a 5 volt regulator is already in the pcb i presume?
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Old 30th September 2013, 03:27 AM   #14
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Quote:
Originally Posted by tubo View Post
So a 5 volt regulator is already in the pcb i presume?
Yes, the control board contains a 5 volt regulator part, however used differently akin to a VRef/R circuit.

Cheers / Chris
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Old 30th September 2013, 03:32 AM   #15
tubo is offline tubo  Philippines
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Im really interested on this one however i have just recently completed a vcpre group buy and have not installed it in my system.

I'llkeep this in mind for the next project
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Old 30th September 2013, 03:59 AM   #16
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Default Volume Pot

Hi Chris, quite interested in this little unit of yours, but i do not know the pot you are using, can it be sustituted for a 50K stepped Dales Resitor pot.
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Old 30th September 2013, 04:56 AM   #17
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Quote:
Originally Posted by tabarddn View Post
Hi Chris, quite interested in this little unit of yours, but i do not know the pot you are using, can it be sustituted for a 50K stepped Dales Resitor pot.
Hi Tabarddn
The pot we use is a bourns 50k single type, it has proved itself over many years of development to be an excellent part for this task. with no failures of any kind.

Yes it can be substituted with other switched type resistor pots, the pot is of course processing DC. In our circuit we use the pot wiper to deliver to each anode LDR pair that then is seeking ground with its cathode- note the pot, as normally occurs is not grounded on one side. So low resistance near 5 ohms or less is ideally needed at each resistance end, because we need to deliver to the LDR

A few years back I converted with much success a Audio Synthesis Passion to be a 4 input LDR. I recall I had to parallel the hubs normally used for each channel to get sufficiently low resistance, rather than any de soldering of Vishay's from the exceptionally nice Shallco switch.

Cheers / Chris

Last edited by Chris Daly; 30th September 2013 at 05:13 AM.
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Old 30th September 2013, 08:34 AM   #18
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Default Switched pot

Hi, thanks, Hum I am an electronic Luddite, are you saying that the pot does not add or distract from the sound. Your Ebay add seems to me anyway only to suggest that your units are in/out put controllers.
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Old 30th September 2013, 09:07 AM   #19
awty is offline awty  Australia
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Quote:
Originally Posted by Chris Daly View Post
Hi Paul
Have you had a chance to listen to it ? If so can you comment how it compares with other pre amps you might have used.

Cheers / Chris
Chris I built your LDR to be used with a future kit amp I'm going to build and its just temporarily connected to SS amp built by Richard McDonald in Adelaide which already has volume control, not sure how its configured, but as Richard hand wires everything point to point and is a minimalist , I'd assume it is passive. Amp only has one pair of RCA connectors.
Been busy with work and haven't had a great deal of time to listen to music. I haven't got much to compare with either. Give me some time and I probably can give a better opinion.
But I will say for now, it certainly doesn't seem to detract from the sound of the amp. Volume is even and continuous, balance seems to be spot on (I've heard that balance can be a problem with LDR's) everything is clear and precise, plenty of wide open soundstage, its quiet.....Tiss good am happy. Cant wait to hear it coupled to its own amp.

BTW is there a shelf life with LDR's?
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Last edited by awty; 30th September 2013 at 09:20 AM.
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Old 30th September 2013, 10:06 AM   #20
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Quote:
Originally Posted by tabarddn View Post
Hi, thanks, Hum I am an electronic Luddite, are you saying that the pot does not add or distract from the sound. Your Ebay add seems to me anyway only to suggest that your units are in/out put controllers.
Hi tabarddn
You are comparing I think, a conventional L Pad potentiometer with an LDR, they are quite different.

Light Dependant Resistor circuits use the potentiometer simply to alter DC current and voltage delivered to the LED half of the LDR. after that just Light causes a variable resistor to change its resistance inside the LDR's encapsulated space .

Advanced Photonix Canada, Inc.: Products: Audiohm Optocouplers: Principles of Operation

This is the wonderful and special thing about LDR's there are no switches or contacts. In my circuit we take this further still removing any signal switching, and we solder the signal wire on one side with a short circuit board trace, and the other directly to the RCA to give you the best listening experience.



Cheers / Chris
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