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Optical Volume Control Professional PCB

Which soldermask colour do you prefer for future PCB´s?

  • red

    Votes: 66 13.3%

  • green

    Votes: 118 23.8%

  • yellow

    Votes: 54 10.9%

  • black

    Votes: 97 19.6%

  • white

    Votes: 52 10.5%

  • blue

    Votes: 108 21.8%
  • Total voters
    495
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#264
Hello Oliver,

this is my assembly:



Your board, 100K Dual log Poti connected via a no more used Floppy Disk cable to the position of the poti on your board (so I can install your board anywhere in my DIY-AMP's case and install the poti into the front plate), driven by a Toshiba Laptop Power-Supply, supplying 6A at 15V (that it why I connected a 68 Ohm resistor between the Toshiba's output and the 7805 so that approximately 4 Ohm will drop across the resistor), trimmers adjusted to 0 Ohm and then I did the measurements.

Here is the result:



Dual Poti at its leftmost position: left Series LDR: ??? Right Series LDR: ???
Dual Poti at 7:00 o'clock position: left Series LDR: 5.91K Right Series LDR: 6.59K
Dual Poti at 9:00 o'clock position: left Series LDR: 5.68K Right Series LDR: 6.51K
Dual Poti at 12:00 o'clock position: left Series LDR: 4.81K Right Series LDR: 5.32K


How to proceed right now? Turn the trimmer of the left Series LDR?


Best regards - Rudi Ratlos
 
Last edited:
#265
#266
@ Rudi Ratlos

I think this "How to" from George should help. 😉


georgehifi said:
Before doing this try to get all 4 LDR's touching each other and pot them in hard wax, this keeps them thermally balanced.

You only need the 1k calibration trimpot on the louder of the two channels, omit the trimpot on the lower level channel and direct couple it still leaving in the 100ohm resistor, do a fine calibration balance between the two channels so you can get them to track equally and have the imaging centered for all levels of playback.

There are 3 ways of doing this from most accurate to least accurate.

1: I do this using a 1khz sine wave from a audio signal generator with a good dual trace oscilloscope.

2: It can be done if you don't have these by using test disc that has a
-20db 1khz sine wave and then use a digital multimeter set at 2vac to do the calibration.

3: Then the really ruff way if you have non of these is to use a mono recorded cd of voice and adjust the 1k trimpot so you have a central image.

4: Always do this calibration after the Lightspeed Attenuator has been on and warmed up for at least 15mins at half volume.

Cheers George
Click to expand...
 
#267
Parts Kit

Hi to all,

because there were many requests in the past, if i also sell the needed parts
for the Lightspeed Attenuator / Optical Volume Control PCB,
i have decided to make a Parts-Kit.
This Kit included all needed parts excluding the LDR´s.

The prices are:

Parts-Kit: 30,00 USD
Worldwide shipping: 9,00 USD
3,9% paypal fee: 1,52 USD

Complete price: 40,52 USD


Best regards,
Oliver​
 
#268
optical volume control doesn't mute

Hello guys,

Just finished my LDR attenuator. First impression: sounds great, especially in the dynamics department.

I have got a question though. Is it true the optical volume control doesn't mute? My volume control attenuates perfectly by turning the pot clockwise, but I can't seem to mute the music by turning the pot completely counterclockwise.

Have I missed something, or did I do something wrong putting it together? Any ideas?
 
#271
dvb-projekt said:
Hi to all,

because there were many requests in the past, if i also sell the needed parts
for the Lightspeed Attenuator / Optical Volume Control PCB,
i have decided to make a Parts-Kit.
This Kit included all needed parts excluding the LDR´s.

The prices are:

Parts-Kit: 30,00 USD
Worldwide shipping: 9,00 USD
3,9% paypal fee: 1,52 USD

Complete price: 40,52 USD


Best regards,
Oliver​
Click to expand...

PM sent
 
Last edited:
#273
dvb-projekt said:
@ Rudi Ratlos
I think this "How to" from George should help. 😉
Click to expand...

2: It can be done if you don't have these by using test disc that has a
-20db 1khz sine wave and then use a digital multimeter set at 2vac to do the calibration.

Hi Oliver,

Can you please elaborate on test #2 from your quoted post #266. What I'm trying to find out is the steps in calibration if I have 1khz sine wave disc or maybe you can give me the links. I'm having a teary eyes already reading some of pages of more than 316 pages of Ligthspeed Attenuator.

Thanks,

Joe
 
#275
dvb-projekt said:
Hi Joe,
if i understand your question right, you want to know how to calibrate
with test #2 ?!
Click to expand...


Hi Oliver,

Yes, I want to know if I need to calibrate at different (volume control pot)volume level, do I need to adjust the adjustable (left/right) pot at every level (high volume or low volume settings) if there is difference on value using the AC voltmeter?
I read it somewhere on how to adjust the lightspeed a while back but I can't seem to find it.

Thanks,

Joe
 
#276
joemana said:
Hi Oliver,

Yes, I want to know if I need to calibrate at different (volume control pot)volume level, do I need to adjust the adjustable (left/right) pot at every level (high volume or low volume settings) if there is difference on value using the AC voltmeter?
I read it somewhere on how to adjust the lightspeed a while back but I can't seem to find it.

Thanks,

Joe
Click to expand...

Hi Joe,

try to adjust the voltage difference on two or three positions of the pod to
the smallest value. That´s it.

Best regards,
Oliver
 
#280
george doesnt sell a kit, he sells a finished product.

i kind of wish he sold a kit, it would have made this so much easier, or at least if he would 'license' his kit to one of the guys on the forum to make it easier for diy'ers to build something on their own even if it is a kit.
 
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