Dual mono passive Pre amp, single ended (advice)

[walpurgis]

This is all rather like the debate in the late sixties/early seventies, over which was best. Valve or transistor amps. The solid state tended to measure better, but many heard valves as sounding better.

[walpurgis]

James, Sovereign presently has the LDr loaner unit which I built many years ago. I will arrange with James for its return here to New Zealand- to update its boards, then provide it back so each one of you can hear what we are hearing - does that sound like a good idea ?

There are those who will refuse to listen to it. They will not accept that it can be good, as it won't measure in a way that suits their 'technical parameters'!

[Clive]

I concur with the posts that say TVCs / AVCs sound clearer / better than pots and sw atts. This fidelity is nothing like the tailoring of sound which SE amps can bring in that the TVC / AVC sound is generally very pure and unadulterated.

[Light Dependant Resistor]

There are those who will refuse to listen to it. They will not accept that it can be good, as it won't measure in a way that suits their 'technical parameters'!

Yes there will always be a minority like this, but WHY their technical parameters = prejudices, cause this- you have to wonder ? A cloth might help - where it is placed might have to be discussed.

[walpurgis]

Oh. And by the way Chris. If there is a 'loaner' LDR to be available. I'd like to try it!

[Light Dependant Resistor]

Hi Geoff
It should be back in the UK early February, so you are first on the list.
I have asked James to be its guardian with loans out of 2 weeks duration
then back to James. Thanks

Cheers / Chris

[Light Dependant Resistor]

Sorry posted twice.

[walpurgis]

Hi Geoff
It should be back in the UK early February, so you are first on the list.
I have asked James to be its guardian with loans out of 2 weeks duration
then back to James. Thanks

Cheers / Chris

I'll look forward to that. Thanks.

[RothwellAudio]

Cryptic ? How can an LDR be anything other than an LDR ?
Perhaps you mean removing the mechanical wiping and grinding of conventional pots,
and ridding circuits of signal side input switching, all good reasons why.

Sorry, I don't understand your post, it makes no sense to me.
Let me clarify what I was trying to say. An "LDR passive" is really just a resistor-based potential divider just like a pot or a stepped attenuator. If the other pre-amps being compared by Sovereign were active pre-amps there would be such a lot of circuit differences between them and the "LDR passive" that the specific type of volume control would be swamped by all the other differences. Simply being passive rather than active would be the biggest difference between the LDR passive and the rest of the group.

My views on light dependent resistors as volume controls are that they are just resistors with resistance that depends on the amount of light shining on them, just like the name suggests. However, they're not particularly good resistors compared to what else is available, and controlling them with light makes it difficult to maintain good left/right channel matching. So what's the advantage? Well, it is claimed than the absence of a mechanical contact point is an advantage, but all switches rely on such contacts, as do all audio connectors, so I'm not convinced by that argument. To me it is just a very complicated way to form a potential divider with two resistors. I would prefer to use two good quality resistors and a switch.

[Arkless Electronics]

Sorry, I don't understand your post, it makes no sense to me.
Let me clarify what I was trying to say. An "LDR passive" is really just a resistor-based potential divider just like a pot or a stepped attenuator. If the other pre-amps being compared by Sovereign were active pre-amps there would be such a lot of circuit differences between them and the "LDR passive" that the specific type of volume control would be swamped by all the other differences. Simply being passive rather than active would be the biggest difference between the LDR passive and the rest of the group.

My views on light dependent resistors as volume controls are that they are just resistors with resistance that depends on the amount of light shining on them, just like the name suggests. However, they're not particularly good resistors compared to what else is available, and controlling them with light makes it difficult to maintain good left/right channel matching. So what's the advantage? Well, it is claimed than the absence of a mechanical contact point is an advantage, but all switches rely on such contacts, as do all audio connectors, so I'm not convinced by that argument. To me it is just a very complicated way to form a potential divider with two resistors. I would prefer to use two good quality resistors and a switch.

Once again I fully agree. LDR's form spectacularly bad resistors with easily measurable and non linear distortion. Even the old carbon resistors from a 1970's TV are wonderful in comparison to a LDR!