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-   -   Preamp: Comparing LDR and buffered LDR (http://www.diyaudio.com/forums/analog-line-level/188768-preamp-comparing-ldr-buffered-ldr.html)

Dr.H 10th May 2011 06:02 PM

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

ZUM911 13th May 2011 12:06 AM

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

Dr.H 13th May 2011 09:07 AM

Thanks for that. Was that the dc coupled B1 or the one requiring input caps?

ZUM911 15th May 2011 12:39 AM

The one here

http://www.diyaudio.com/forums/analo...reamp-137.html

carlmart 15th May 2011 02:03 PM

Rick,

Quote:

Originally Posted by ZUM911 (Post 2570232)
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

ZUM911 16th May 2011 12:47 AM

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

udailey 4th October 2011 02:43 PM

Rick,
Try buffer on output of LS. On my system its best this way.
Uriah

ZUM911 5th October 2011 01:29 AM

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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