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Arduino based LDR volume and source selection controller
Arduino based LDR volume and source selection controller
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Old 5th January 2016, 02:52 PM   #131
tfboy is offline tfboy  United Kingdom
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Quote:
Originally Posted by didiet78 View Post
Anything to change in code if LDR RSE/LSE replaced with fixed resistor (Shunt volume control)?
If you're replacing the LDR with a fixed resistor, you would need a complete re-write of the code as it uses the variable resistance at measured voltages to control the attenuation.
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Old 5th January 2016, 08:51 PM   #132
Vincent77 is offline Vincent77  Europe
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Quote:
Originally Posted by AndrewT View Post
One of our Members used a big electrolytic across the LED to filter out the noise that could be picked up by the cables from the 100k pot to the LED pins.
I wonder whether the big electrolytic is still effective at the high frequencies of the noise...

We used here a ceramic or film cap placed where the LED power supply cables connect to the board.
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Old 5th January 2016, 08:53 PM   #133
Vincent77 is offline Vincent77  Europe
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Quote:
Originally Posted by tfboy View Post
If you're replacing the LDR with a fixed resistor, you would need a complete re-write of the code as it uses the variable resistance at measured voltages to control the attenuation.
Yes, as tfboy said, no easy way to do that without rewriting a lot of code.
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Old 8th January 2016, 03:03 AM   #134
wineds is offline wineds  Australia
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@Vincent, I finally got some time to assemble and hook up the input board. The solderability of the boards from shenzhen2U was poor this time - there must have been some sort of film on them. After cleaning with isopropanol they were OK.

Everything seems to work OK. A few minor issues :

1. There is a loud pop when I switch from a loaded input to an unloaded one. I may look at the code to see if there is any muting ahead of input switching?
2. After switching inputs the -> on the display changes to a square cursor like block. If you press the menu key on the remote it changes back to ->. I guess there needs to be one additional display update added somewhere in the code?

Now I will look into putting it all into a case.
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Old 11th January 2016, 01:04 PM   #135
Theodosis O. is offline Theodosis O.  Greece
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Hi Vincent,

I tested yesterday your LDR volume in my system: Esoteric K-03 -> Viva Solista -> Sonus Faber Amati Anniversario.
?????????? ?? ?? Sonus Faber | AVsite

I have to say that it is the most transparent pre I have ever heard. Congratulations.

I had a small issue with the enconder but I used 2 100n to cw/ccw and is OK now.

One question: Can it drive a power amp. with 10K or a power amp. with 47K input impedance. Why you write in the code that it must be over 100K ?

Thanks.

Last edited by Theodosis O.; 11th January 2016 at 01:08 PM.
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Old 19th January 2016, 08:10 PM   #136
Vincent77 is offline Vincent77  Europe
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Quote:
Originally Posted by wineds View Post
1. There is a loud pop when I switch from a loaded input to an unloaded one. I may look at the code to see if there is any muting ahead of input switching?
2. After switching inputs the -> on the display changes to a square cursor like block. If you press the menu key on the remote it changes back to ->. I guess there needs to be one additional display update added somewhere in the code?
Hello!

There is indeed a faint pop when I switch between the inputs, but in my preamp it is not loud - I didn't notice it before.
But I agree, I should temporarily mute the output while switching the inputs, thanks for the idea! I'll write the code when I have some time. It's not difficult, you might be able to do it yourself.

After switching the inputs or the outputs, the arrow changes indeed to a block, to mark the active line - you can switch the active line with the middle remote button, to choose between the inputs and the outputs.
The block automatically changes back to an arrow after a few seconds.

Vincent
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Old 19th January 2016, 08:29 PM   #137
Vincent77 is offline Vincent77  Europe
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Quote:
Originally Posted by Theodosis O. View Post
Hi Vincent,

I tested yesterday your LDR volume in my system: Esoteric K-03 -> Viva Solista -> Sonus Faber Amati Anniversario.
?????????? ?? ?? Sonus Faber | AVsite

I have to say that it is the most transparent pre I have ever heard. Congratulations.

I had a small issue with the enconder but I used 2 100n to cw/ccw and is OK now.

One question: Can it drive a power amp. with 10K or a power amp. with 47K input impedance. Why you write in the code that it must be over 100K ?

Thanks.
Hello Theodosis,

I am glad that you like the LDR attenuator and congrats for your nice audiophile system!
Sorry I didn't respond earlier, but I was on holidays (in Greece, lovely country).

You can drive an amp with 47K input impedance without problems. Set
#define LOAD_IMPEDANCE 47000
in the code and it will work ok.

I wrote in the code that it should be 100K because usually we want the load impedance to be larger than the source impedance, but 47k or even 25k amplifier input impedance should be ok.

You may also want to try to set the nominal impedance of the LDR attenuator to
#define NOM_IMPEDANCE 5000
and see if you like it more than 10000 (of course you will have to do a calibration process each time you change these parameters).

Vincent

Last edited by Vincent77; 19th January 2016 at 08:31 PM.
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Old 20th January 2016, 10:28 AM   #138
Theodosis O. is offline Theodosis O.  Greece
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Thank you Vincent,

Actually, my First One amplifier has 10K input impedance.

So I will set LOAD_IMPEDANCE=NOM_IMPEDANCE=10000
Is it OK for your LDR volume, regarding sound quality ?

(You must visit the Greek islands in summer !!!)

Last edited by Theodosis O.; 20th January 2016 at 10:32 AM.
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Old 20th January 2016, 11:27 AM   #139
massimo is offline massimo  Italy
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Originally Posted by Theodosis O. View Post
(You must visit the Greek islands in summer !!!)
Flights already booked for August! As usual...
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Old 20th January 2016, 06:14 PM   #140
Vincent77 is offline Vincent77  Europe
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Quote:
Originally Posted by Theodosis O. View Post
Thank you Vincent,

Actually, my First One amplifier has 10K input impedance.

So I will set LOAD_IMPEDANCE=NOM_IMPEDANCE=10000
Is it OK for your LDR volume, regarding sound quality ?

(You must visit the Greek islands in summer !!!)
Hello,

Yes, it will work!

BTW, I was in Athens and Santorini last week.
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