Preamp: Comparing LDR and buffered LDR

Dr.H · 10th May 2011, 06:02 PM

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

Lightspeed Attenuator a new passive preamp

carlmart · 15th May 2011, 02:03 PM

Rick,

Quote:

Originally Posted by ZUM911

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

10th May 2011, 06:02 PM	#1
Dr.H diyAudio Member Join Date: Apr 2002	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

4th October 2011, 02:43 PM	#7
udailey Passive Aggressive diyAudio Member Join Date: Mar 2008	Rick, Try buffer on output of LS. On my system its best this way. Uriah __________________ You can purchase LDRs anytime to build a standard LDR attenuator or to build my new LDR Attenuator "A Lighter Note". Email me. diyldr@gmail.com

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13th May 2011, 12:06 AM	#2
ZUM911 diyAudio Member Join Date: Jan 2006 Location: Sydney	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

13th May 2011, 09:07 AM	#3
Dr.H diyAudio Member Join Date: Apr 2002	Thanks for that. Was that the dc coupled B1 or the one requiring input caps?

15th May 2011, 12:39 AM	#4
ZUM911 diyAudio Member Join Date: Jan 2006 Location: Sydney	The one here Lightspeed Attenuator a new passive preamp

16th May 2011, 12:47 AM	#6
ZUM911 diyAudio Member Join Date: Jan 2006 Location: Sydney	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

5th October 2011, 01:29 AM	#8
ZUM911 diyAudio Member Join Date: Jan 2006 Location: Sydney	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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