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Old 7th March 2013, 07:45 PM   #4991
udailey is offline udailey  United States
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we can assume its wired correctly but how can we know without seeing the whole thing?
It sounds like the ldrs are in backwards. I think they probably measure in megohms no matter what you do with volume pot.
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Old 7th March 2013, 08:05 PM   #4992
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Follow this, it works.
And if you still think you have a thin sound then it could be your source has weak output stage or your poweramp is very low input impedace.
Cheers George
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Old 7th March 2013, 08:14 PM   #4993
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Just saw you are using dual mono volume control (led controlers) this is the circuit for that.

Cheers George
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Old 7th March 2013, 08:52 PM   #4994
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Quote:
Originally Posted by georgehifi View Post
Just saw you are using dual mono volume control (led controlers) this is the circuit for that.

Cheers George
I think that's certainly different to what I've done. I'll give that go. Thanks George.
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Old 7th March 2013, 09:37 PM   #4995
udailey is offline udailey  United States
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Look closer. Hes got 3 pots. My bet is one pot is 100k and two are 1k so hes using your original schematic which is actually the same schematic he 'quoted' in his original post.
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Old 8th March 2013, 12:04 PM   #4996
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Gentlemen,

in my eyes (ears) George's "Lightspeed Attenuator" is the best volume attenuation that I have come across in the past,
and I will give it a definite "GO" for my current PCB design (being controlled by an Infrared-controlled motorized potentiometer).

Best regards - Rudi_Ratlos
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Old 8th March 2013, 05:02 PM   #4997
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I agree, my Lightspeed Attenuator sounds great. I use it in a DAC/Pre amp I built and I use an Alps 100K log dual motorized pot controlled via a microprocessor and infra red.
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Old 8th March 2013, 05:22 PM   #4998
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Quote:
Originally Posted by kristeva View Post
It plays at low volume, sounding quite thin....


apologies for the crap picture

Any advice appreciated. Thanks.
hope you got it fixed

but gosh.... you really need to look closer at you soldering quality too
please use magnifying glass and check everything carefully
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Old 9th March 2013, 01:06 PM   #4999
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got some time over the weekend to get back this. Uriah is right, mine is a 3 pot configuration as in the original schematic posted.

This is what I tried to build:

Click the image to open in full size.

Uriah, when I originally questioned if it was 'wired correctly' I was referring to the schematic above, but I understand what you're saying - I'll post some more pics of the full build.

I realized George's schematic wasn't quite the same soon after he posted it. I might try that design if I can't get this to work. But for now I'll go back and recheck my build again.

tinitus, yes I know it's a bit of mess but those pots were 'donated' to me from another LS amp and were already scruffy. I'll recheck everything, just wanted to check I'd wired it up correctly in relation to the above schematic.

P
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Old 9th March 2013, 02:14 PM   #5000
udailey is offline udailey  United States
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The "schematic"/drawing I posted years ago that you show is correct. It was made for folks who have trouble with schematics. The Lightspeed is often a first project. If you rewire anything please use your thinnest wire to be kind to the pots and ldrs. Heat is bad for both and thick wires take more heat. Please make sure the ldr dots are going to negative/0V. Also make sure that the ldr long/round leads go to signal and short/flat go to power. These are often the reason for thin sound because the ldrs are at megohms.
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