LDR att. L+R imbalance?

[redmaster]

Hi,
A friend of mine built an attenuator based on LDR design.
I noticed that L+R channels are imbalanced.
when the pot knob is turned up, it starts from R channel +5dBFS louder then L channel (minimum),
but when knob turning up, the imbalance gets smaller and smaller, until around -20dbFS (around middle) it's almost perfect, then Left channel (when turning up) became louder and louder - up to -5dBFs, and it's almost perfect when in full 'open' position.
I was told it is just a problem with LDR and it possibly can't be resolved, but I remember reading some audio purist using LDR att. and I don't think they wouldn't notice a 5dB difference between channels, so I presume it's possibly to have it ideal (0.1dB - I can live with, 0.2dB - would be maximum)
Could you please help me - what could cause this sort of problem ?
How to resolve it ?
Is it simply swapping a pair of LDRs or sth else ?
I really appreciate your help, here - thank you in advance
If LDR design is not perfect and it's very difficult to find pair of LDR with 0.1dB difference - could you please advise me, what type of passive att. would be good ? - in a 'human - 99%' price range

[Mooly]

Originally Posted by redmaster

If LDR design is not perfect and it's very difficult to find pair of LDR with 0.1dB difference - could you please advise me, what type of passive att. would be good ? - in a 'human - 99%' price range

Now let me say first of all I have never built a Lightspeed, but when I first read about it my first thought was that matching L and R channels and getting them to track accurately and maintain that accuracy long term might be somewhat difficult.

Personally, I would go for something like an ALPS motorised pot every time.

[redmaster]

Originally Posted by Mooly

Now let me say first of all I have never built a Lightspeed, but when I first read about it my first thought was that matching L and R channels and getting them to track accurately and maintain that accuracy long term might be somewhat difficult.

Personally, I would go for something like an ALPS motorised pot every time.

I don't need remote pot, but could you elaborate on this ALPS please ?

[Mooly]

The ALPS is the classic quality audiophile pot that has been used for decades, for example

ALPS|RK27111250K|POTENTIOMETER, 50K | Farnell United Kingdom

[redmaster]

Thank you for your input, so do you think ALPS is 'close' with sound quality to ldr ? if yes, then maybe I'll drop the idea with ldr....
I dunno I am not constructor myself, my knowledge in the area is minimal.....

[Mooly]

I can't really comment on the LDR type control for sound quality as I haven't built one.

The ALPS has always been the "Gold Standard" for quality attenuators and I and countless others (manufacturers and diy) have never had a problem.

The LDR "Lightspeed" is an intriguing concept but the wide tolerance of the LDR's to me implies close channel matching will be difficult without a lot of individual tweaking and compensating.

[redmaster]

Originally Posted by Mooly

I can't really comment on the LDR type control for sound quality as I haven't built one.

The ALPS has always been the "Gold Standard" for quality attenuators and I and countless others (manufacturers and diy) have never had a problem.

The LDR "Lightspeed" is an intriguing concept but the wide tolerance of the LDR's to me implies close channel matching will be difficult without a lot of individual tweaking and compensating.

I am bending towards ALPS, or anything with best sound quality possible, but also without L/R imbalance.
thanks for your input, do you think ALPS is as best as it gets ?
or it is a chance to invest a bit more in pot and have better sound ?
what about goldpoint or this :
HiEnd attenuator 48 steps silver passive preamp Caddock | eBay
thanks in advance for help

[Ryelands]

Originally Posted by redmaster

I am bending towards . . . anything with best sound quality possible, but also without L/R imbalance.

The Lightspeed does not normally suffer from severe channel imbalance. If you are experiencing it, you have either made an error when building the device or have mismatched components.

Why not post on the main Lightspeed thread as you can get advice from those who have built the thing, know the circuit well and don't need to imply its qualities or limitations?

FWIW, my experience with both the Lightspeed and The Lighter Note is that they knock spots off switched attenuators when it comes to preserving detail. Though I suspect that even I would notice a 5 dB swing, I haven't experienced balance issues.

[redmaster]

Originally Posted by Ryelands

The Lightspeed does not normally suffer from severe channel imbalance. If you are experiencing it, you have either made an error when building the device or have mismatched components.

Why not post on the main Lightspeed thread as you can get advice from those who have built the thing, know the circuit well and don't need to imply its qualities or limitations?

FWIW, my experience with both the Lightspeed and The Lighter Note is that they knock spots off switched attenuators when it comes to preserving detail. Though I suspect that even I would notice a 5 dB swing, I haven't experienced balance issues.

I did it already,
I do not imply it's quality or/and limitations, I am just asking, I need device with up to 0.2 dB imbalance
LDR l+r imbalance - YouTube
if you watch this vid, you'll notice it's not about constant difference L/R channel,
but this is inconstant, permanently changing...
I don't know myself which way to go....I'd like to utilize ldr design, as it seems for me almost ideal for audio purist,
I am seeking answer, could anyone who owns ldr design can check if their box is accurate ?
thanks for input

[redmaster]

just to add- on video ldr was fed with 1kHz looped wave