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Old 10th May 2011, 07:02 PM   #1
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Default Preamp: Comparing LDR and buffered LDR

Since the lightspeed was introduced, a few new versions have been made, specifically with a buffered output, typically based on the B1 buffer of Nelson Pass.

Has anyone compared the unbuffered vs the buffered LDR preamps. I have a Krell KSA80 B which has about 47k input impedance
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Old 13th May 2011, 01:06 AM   #2
ZUM911 is offline ZUM911  Australia
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I built both George's original Lightspeed and Nelson's buffered versions. On the buffered version I put the buffer at the input to help match my source. They both were a great improvement in my system. I did not hear any obvious drawbacks to the buffered version so that's what I use.

Rick
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Old 13th May 2011, 10:07 AM   #3
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Thanks for that. Was that the dc coupled B1 or the one requiring input caps?
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Old 15th May 2011, 01:39 AM   #4
ZUM911 is offline ZUM911  Australia
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The one here

Lightspeed Attenuator a new passive preamp
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Old 15th May 2011, 03:03 PM   #5
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Rick,

Quote:
Originally Posted by ZUM911 View Post
I built both George's original Lightspeed and Nelson's buffered versions. On the buffered version I put the buffer at the input to help match my source. They both were a great improvement in my system. I did not hear any obvious drawbacks to the buffered version so that's what I use.
1) What source is that that you need a buffer for? What output impedance?

2) What happened if you used just George's version, with no buffer?


Carlos
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Old 16th May 2011, 01:47 AM   #6
ZUM911 is offline ZUM911  Australia
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Calmart,

My CD player has a Zout of about 150 Ohm and my Pearl phono stage is quite a bit higher if I'm not mistaken. George was recommending 50 Ohm input to the Lightspeed so I put the buffer in front. The frequency range seems more extended with the buffer. No testing other than my ears.

Rick
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Old 4th October 2011, 03:43 PM   #7
udailey is offline udailey  United States
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Rick,
Try buffer on output of LS. On my system its best this way.
Uriah
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purchase LDRs anytime Also try my Resistor Replacers or LDR based Input Selector Email me. diyldr@gmail.com
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Old 5th October 2011, 02:29 AM   #8
ZUM911 is offline ZUM911  Australia
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Hi Uriah,

I did try that. I also had both input and output buffers but ended up with too much dc and didn't want coupling caps so the input buffer won out in my system. It is definitely worth exploring all options, though.

Rick
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