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Old 5th April 2011, 07:32 PM   #4061
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George - what a good idea! I entirely agree that its key to have minimum dry joints in the signal path, (or the power supply for that matter) but I currently have just one - the volume control. I am definately going to try this! Rgds
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Old 5th April 2011, 08:43 PM   #4062
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Thanks Geoff, here is a circuit you can follow, it's the production version MkII, and also the purist version, the supply shown is just as good as pure battery power, so no need to good any more exotic with it.
And if you want, you use two single 100k log pots instead of a dual, then that way you have balance (dual mono) for awkward shaped rooms or unbalanced systems.

Cheers George
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Old 12th April 2011, 08:26 PM   #4063
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George, many thanks for the circuit. I will build two separate mono units, since they will be located each on their own loudspeaker. This means that I am not too worried about matching!

I'm now thinking about a similar solution to the selector switch problem - do you have any experience? (I've been unable to play anything but vinyl since soldering in my source to get the sound quality - a shame since I have a Nak tape deck and a Leak tuner standing dumb!)

Best regards
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Old 12th April 2011, 09:11 PM   #4064
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Here is one I have on file, 3 inputs, but it needs a few ldr's, but not impossible.
You guys also will be happy to know that the Lightspeed Attenuator has made Class B in preamps again in Stereophile Recommended Components, it got 5 star value as well because most of Class B is $3K +.
An email to me said it would never get to Class A because of it's $470 price, how's that for $'s count in what placement you get.

Cheers George
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Old 13th April 2011, 09:02 AM   #4065
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Hi G,
I like the single common shunt element. So simple !
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Old 13th April 2011, 10:00 AM   #4066
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Hi Andrew, yeah simple in theory, and automatically shorts out the two unused inputs, but what a nightmare to match up the 14 ldr's for stereo use, wouldn't wish it on my worse enemy. Why can't somebody make the perfectly consistent ldr's. Suppose then I'd be out of business.

Cheers George
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Old 13th April 2011, 11:20 AM   #4067
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Default why 2 series ldrs?

Quote:
Originally Posted by georgehifi View Post
Hi Andrew, yeah simple in theory, and automatically shorts out the two unused inputs, but what a nightmare to match up the 14 ldr's for stereo use, wouldn't wish it on my worse enemy. Why can't somebody make the perfectly consistent ldr's. Suppose then I'd be out of business.

Cheers George
George,
A quick question: why are 2 series LDRs needed with the muting relay? I'd think you could just put the relay to gnd after or before the (one) series LDR.
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Old 13th April 2011, 11:23 AM   #4068
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think input and output impedances.
Draw it out and see what difference that extra LDR resistances does.
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Old 13th April 2011, 11:42 AM   #4069
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Quote:
Originally Posted by georgehifi View Post
Here is one I have on file, 3 inputs, but it needs a few ldr's, but not impossible.
it would be nice if you mention that the original idea came from here: www.audiofaidate.org - lightspeed attenuator+progetto HiFun controllo pre
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Last edited by UnixMan; 13th April 2011 at 11:49 AM.
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Old 13th April 2011, 12:09 PM   #4070
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it would be nice if you mention that the original idea came from here:
Which icon should I toggle to see an english translation?
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