LDR - anyone use it ? Any comment ?

by wabun Tue Jan 05, 2010 10:04 pm

Light Detection Resistor -LDR as passive preamp. I heard ppl said it sounds better than step attenuator, better than relay switched passive, better than TVC..bla bla
is there any kaki using it now ? any comment please...

by mugenfoo Tue Jan 05, 2010 11:11 pm

Everyone waiting for u to build the new Jumban3 pre-amp using LDR !!

Faster go make one and test lah ! .... Might get Class AAA from Stereophile also !

by wabun Wed Jan 06, 2010 11:26 am

ei, you are true genius woh, I really plan that. LDR - anyone use it ? Any comment ? Icon_biggrin

by sflam Tue Jan 26, 2010 5:54 pm

ldr actually stands for 'light dependent resistor'

i just heard an ldr preamp today. it is not a pure ldr passive preamp since it has a buffer section.
according to the designer, the ldr preamp by itself sounds clean and transparent but lacks dynamics much like a normal passive preamp.
the buffer provides the drive.

in the system that it was in, i thought it (ldr plus buffer) sounded quite good and did not lack dynamics or sound thin.

as for ldr on its own, i don't know and can only trust the designer's ears.

by Razz Tue Jan 26, 2010 9:17 pm

i have passive ldr pre...sound very goooodd....now in process finishing dc couple buffer stage with shunt regulator.

by CT-Boy Fri Jan 29, 2010 10:33 pm

Razz,
Interesting project there. I assume this is similar to the lightspeed attenuator? Any pics?
Keep us posted on the development. Thanx.

by chua55 Fri Jan 29, 2010 10:37 pm

if u know flyboi, he is the first malaysia to have bought the original LDR (or lightspeed) completely built up commercial unit from Australlia (the guy who created it, and he is active advicing people how to build it).

ask nicholas chua too from promitheus about TVC. has anyone tried the John Curl Blowtorch? what about Salas simplistic Nelson Pass B1

by Razz Sat Jan 30, 2010 4:24 pm

CT-Boy wrote:Razz,
Interesting project there. I assume this is similar to the lightspeed attenuator? Any pics?
Keep us posted on the development. Thanx.

Yes...
I'm still need few things for the B1 buffer...will complete soon but this wont be a single unit as I'm putting with the buffer into a case unit as integrated amplifier....save some space here......but with a different power supply ofcorse....

chua55 wrote:if u know flyboi, he is the first malaysia to have bought the original LDR (or lightspeed) completely built up commercial unit from Australlia (the guy who created it, and he is active advicing people how to build it).

ask nicholas chua too from promitheus about TVC. has anyone tried the John Curl Blowtorch? what about Salas simplistic Nelson Pass B1

Heard his review before about the LSA created by George Stantscheff. Some say LSA is better that the TVC.....and he created this 20 years ago...!

by kp93300 Mon Feb 08, 2010 11:45 am

Hi ,
I have been using this for the last year and to me this is the most transparent pot . The lack of dynamic is all due to too low impedance at the amp . The F5 with 100k input impedance sounds more dynamic than the 47K input impedance of Truepath digital amp.
The timbre and detail is very good. There is no lack of bass with F5 amp.or even the Truepath.
I encourage you to build it and try it out if your amp has at least 50K input impedance.
cheers
kp93300

by noodle88 Sun Feb 14, 2010 10:05 pm

LDR volume control? I heard it from my friend flyboy house. Not so good as they claim. I prefer TVC from s&b, they r much better but hard to find nowadays. I personally like active preamp more than passive ones. Active seems to have more drive n energy in the music.

by Razz Mon Feb 15, 2010 10:41 am

it's matter of taste....maybe youre looking for 'ching bang boom boom' sound but for some, they're looking for natural sound from the LDR.....

kp93300

put a buffer after the ldr, maybe it sounds good. even F5 is 100K but simple buffer wont do harm.....

by noodle88 Mon Feb 15, 2010 2:28 pm

If u want your system to play both vocal n full ochestra, u need an active preamp. Unless u have an intergrated amp. Then u may replace your Stock volume port with LDR. Keep the interconnect between LDR n the driver stage.

As for adding a buffer, it's depands on how good the power supply of the buffer r. A good buffer's psu need to be done very elaborate like a good preamp. Then might as well go for a preamp driving a poweramp. If u have a good active pre then it's no point to add an buffer in between.

My friend have a low output impeadence DAC driving a Lightspeed LDR, and then drive a pair of 250k input impeadence poweramp. He can't get his system sound good, at last he abandon his lightspeed n go for an active preamp.

by Razz Mon Feb 15, 2010 6:16 pm

noodle88 wrote:If u want your system to play both vocal n full ochestra, u need an active preamp. Unless u have an intergrated amp. Then u may replace your Stock volume port with LDR. Keep the interconnect between LDR n the driver stage.

As for adding a buffer, it's depands on how good the power supply of the buffer r. A good buffer's psu need to be done very elaborate like a good preamp. Then might as well go for a preamp driving a poweramp. If u have a good active pre then it's no point to add an buffer in between.

My friend have a low output impeadence DAC driving a Lightspeed LDR, and then drive a pair of 250k input impeadence poweramp. He can't get his system sound good, at last he abandon his lightspeed n go for an active preamp.

nah....I don't listen to vocals nor orchestra....

yes i don't use interconnect...just a short internal wire between buffer and the LDR better that any interconnect....

buffer psu...i guess employing shunt regulator will be good...a lot of diyers have go along this way successfully and i don't see any issue...

all those we see is just a guide, we don't need to be 100% similar to others....KIS is better for me...but just make sure everything is right....

by noodle88 Mon Feb 15, 2010 6:40 pm

As for me, I prefer to use an active preamp rather than buffer. My preamp only consist of a s&b tvc, input trans, a 45 tube n a line output trans in the signal path. U can't get any simple than this..... Further more no cap in the signal path...

Lightspeed LDR will change it sound when it's volume control is being change, changing it's ground cable also change it's sound, change of psu component also change it's sound. So, do u think the LDR sound as good as they claim? My friend told me his LDR passive preamp is the world best preamp, but last week I went to his house n found out he had changed to an active preamp....

For those who want to go into passive preamp need to really try it in your system, do compare it with various passive and active preamp. Trust your ear.....

by vt4c Thu Mar 18, 2010 11:09 am

noodle88 wrote:Lightspeed LDR will change it sound when it's volume control is being change

This shouldn't be the case of a properly done LDR volume control with a matching set-up...Only the volume level will change...Nothing else. LDR - anyone use it ? Any comment ? Icon_biggrin

LDR volume control forte is on its excellent transparency. A LDR volume control used on a matching set-up will give excellent sound-stage...Deep and wide.

Being passive volume control there will be no gain. For a power amplifier that comes with low gain (I suspect this might be your case), it will be less than ideal to pair it with. An active line-stage with the extra gain and signal swing will of-course be a better combination.

OTOH, with the right amplifier, LDR volume control is the best when it comes to fine detail resolution and sound-stage....An added extra gain stage will for sure add something to the signal... Less stage, less thing is added.

by noodle88 Thu Mar 18, 2010 12:24 pm

My friend did change his LDR pot to a alps pot he told me he got better sound.

The question is can a diod be linear??

by tlkoo Thu Mar 18, 2010 2:42 pm

noodleman

when i had the grounding of my power amplifier corrected, my setup sounded just unbearable!!! i later discovered that the culprit was interconnects...

by the same token, i guess the expectedly superior ldr had revealed issues along some point of the music reproduction chain thus the alps unit was mistaken as better sounding

just my some losely founded guess though i wonder if diode could have high linearity

regards
tlkoo

by noodle88 Thu Mar 18, 2010 3:07 pm

tlkoo wrote:noodleman

when i had the grounding of my power amplifier corrected, my setup sounded just unbearable!!! i later discovered that the culprit was interconnects...

by the same token, i guess the expectedly superior ldr had revealed issues along some point of the music reproduction chain thus the alps unit was mistaken as better sounding

just my some losely founded guess though i wonder if diode could have high linearity

The LDR claim that it got only diode in the signal path that why it's so superior. But u change the pot , the power supply, the spike it's all change the sound. Why???
Furthermore, diode is not linear....
Flyboi told me his lightspeed LDR is the world best passive pre but now he himself not using it. Why??

regards
tlkoo

by vt4c Thu Mar 18, 2010 3:47 pm

noodle88 wrote:
My friend did change his LDR pot to a alps pot he told me he got better sound.

Hmmm.....Interesting.

noodle88 wrote:
The question is can a diod be linear??

Can you please kindly elaborate on this? Diod???

by catal2002 Thu Apr 29, 2010 7:21 pm

Hi,

Did you mean Ldr work like a diode.?

KLau

noodle88 wrote:
The question is can a diod be linear??

Can you please kindly elaborate on this? Diod???[/quote]

by tycham Thu Apr 29, 2010 7:40 pm

wabun wrote:ei, you are true genius woh, I really plan that.

You are only in planning stage? Ah Yeo already beat you to it leh!

http://diyparadise.com/web/index.php?option=com_content&task=view&id=147&Itemid=26

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