Sound difference?
Hi,
in past I have tried stepped attenuator ladder type with metal film resistor. Compared to common cheap carbon pot the sound of stepped was somewhat clearer, better soundstage but overall the carbon pot sounds better, more musical, more natural.
How does the lightspeed compares to carbon pot? Is that really big difference, does it sound musical?
I have hard time to believe that it improves sound so much, just with eliminating one wiper contact.
If it does improve the sound so much, why is it so rarely used in commercial sphere?
Last question. I have in my house H11F1 FET-opto coupler. Could I use them? Wouldnt they sound worse then LDR?
Thanks.
Hi,
in past I have tried stepped attenuator ladder type with metal film resistor. Compared to common cheap carbon pot the sound of stepped was somewhat clearer, better soundstage but overall the carbon pot sounds better, more musical, more natural.
How does the lightspeed compares to carbon pot? Is that really big difference, does it sound musical?
I have hard time to believe that it improves sound so much, just with eliminating one wiper contact.
If it does improve the sound so much, why is it so rarely used in commercial sphere?
Last question. I have in my house H11F1 FET-opto coupler. Could I use them? Wouldnt they sound worse then LDR?
Thanks.
Its not just the wiper being absent. The material the LDR is made out of just sounds wonderful. Its so far better than a carbon pot that you really should try it, even if you just stick two unmatched in a series configuration and a regular shunt resistor. It wont sound as good as using two LDRs for each channel but it will give you a taste for a cheap price.
Have no idea how your fet would sound.
Uriah
Have no idea how your fet would sound.
Uriah
LDR vs POT
Great question. And perhaps there should be a bake off with passives. I have been trying to get my hands on TVC units but the used ones sell so quickly. The pots would be easy to build.
At the risk of offending all the audiophiles, at the end it comes down the ability of your equipment to resolve the differences.
Personally, I like the LDR. The FET from the data sheet looks like it will work but being a FET might have other characteristic attached - gain etc. The LDR is also a semiconductor but of different material. So who know what the difference in sound is like.
I just got an FM acoustics amp loaned to me. The biggest difference between them and the others is the very closely matched components. Frankly in my system I could not tell the Mark Levinson($10k) versus the FM Acoustics ($60k). Aside from the system limitations, I am sure my ears have their limitations too.
The Eves apple for me on the LDR is the coolness - no doubt, the fact that I can put the LDR's directly on the XLR Connectors - very short wiring, and have the same other features of the pot - dead silence, vol goes from zero to full (I use warpspeed which allows this), high impedance but no moving parts.
I had a old MC which has the noises volume control. They did change it out but volume controls always give me the hi-bi-ji-bi's.
Plus it is a really entertaining project.
Great question. And perhaps there should be a bake off with passives. I have been trying to get my hands on TVC units but the used ones sell so quickly. The pots would be easy to build.
At the risk of offending all the audiophiles, at the end it comes down the ability of your equipment to resolve the differences.
Personally, I like the LDR. The FET from the data sheet looks like it will work but being a FET might have other characteristic attached - gain etc. The LDR is also a semiconductor but of different material. So who know what the difference in sound is like.
I just got an FM acoustics amp loaned to me. The biggest difference between them and the others is the very closely matched components. Frankly in my system I could not tell the Mark Levinson($10k) versus the FM Acoustics ($60k). Aside from the system limitations, I am sure my ears have their limitations too.
The Eves apple for me on the LDR is the coolness - no doubt, the fact that I can put the LDR's directly on the XLR Connectors - very short wiring, and have the same other features of the pot - dead silence, vol goes from zero to full (I use warpspeed which allows this), high impedance but no moving parts.
I had a old MC which has the noises volume control. They did change it out but volume controls always give me the hi-bi-ji-bi's.
Plus it is a really entertaining project.
ua100k
as to the 'bake off.' I think if you get hold of a TVC you will be very pleased with the outcome of your LDR attenuator vs the TVC. I have been told MANY times that LDRs eat TVC for breakfast. The last time the TVC was one of those 5000usd silver wound deals. The guy literally went and sold his TVC. Complete LDR commitment!
I think LDRs will catch on in a more mainstream environment than just DIY and when that happens affordable HIFI will be but a preamp away.
These arent a fad. They arent a mystery. They arent that hard to control.
They ARE the best sound in a passive. They ARE inexpensive relative to sound quality.
In this forum the most important thing, I think, is that building a Lightspeed is probably the EASIEST AND MOST REWARDING project on the entire DIY site.
I may be slightly biased
But you know why.
Uriah
as to the 'bake off.' I think if you get hold of a TVC you will be very pleased with the outcome of your LDR attenuator vs the TVC. I have been told MANY times that LDRs eat TVC for breakfast. The last time the TVC was one of those 5000usd silver wound deals. The guy literally went and sold his TVC. Complete LDR commitment!
I think LDRs will catch on in a more mainstream environment than just DIY and when that happens affordable HIFI will be but a preamp away.
These arent a fad. They arent a mystery. They arent that hard to control.
They ARE the best sound in a passive. They ARE inexpensive relative to sound quality.
In this forum the most important thing, I think, is that building a Lightspeed is probably the EASIEST AND MOST REWARDING project on the entire DIY site.
I may be slightly biased
But you know why.Uriah
I just got my clone up and running in the lab. No listening done just yet...
Urias previous statement got me thinking though.
The only hurdle before becomming a true consumer product is control and channel matching.
For us in the DIY game it's ok to match components and fiddle with the tiny details.
To become accepted by the crowd I think there must be a ready solution to get the match without doing the actual matching.
Either much better production control or a way to adjust in real time.
The only ideas I have on the subject are rather fiddly. Like using a HF calibrating signal and filter after the LDRs? The passive dream is quickly lost.
Myself I'm working on the case at the moment. I'm going to try and CNC the front and back plate for the enclosure.
Urias previous statement got me thinking though.
The only hurdle before becomming a true consumer product is control and channel matching.
For us in the DIY game it's ok to match components and fiddle with the tiny details.
To become accepted by the crowd I think there must be a ready solution to get the match without doing the actual matching.
Either much better production control or a way to adjust in real time.
The only ideas I have on the subject are rather fiddly. Like using a HF calibrating signal and filter after the LDRs? The passive dream is quickly lost.
Myself I'm working on the case at the moment. I'm going to try and CNC the front and back plate for the enclosure.
ua100k
as to the 'bake off.' I think if you get hold of a TVC you will be very pleased with the outcome of your LDR attenuator vs the TVC. I have been told MANY times that LDRs eat TVC for breakfast. The last time the TVC was one of those 5000usd silver wound deals. The guy literally went and sold his TVC. Complete LDR commitment!
I think LDRs will catch on in a more mainstream environment than just DIY and when that happens affordable HIFI will be but a preamp away.
These arent a fad. They arent a mystery. They arent that hard to control.
They ARE the best sound in a passive. They ARE inexpensive relative to sound quality.
In this forum the most important thing, I think, is that building a Lightspeed is probably the EASIEST AND MOST REWARDING project on the entire DIY site.
I may be slightly biased
Uriah
Been there, done that. I spent over $500 for a pair of P&G "Faders", 20k stereo units, each to be wired as a mono pot with wipers in parallel and used as a dual channel volume control, because to that point, a pair of P&G faders, wired that way, was the best I'd heard.
Our DIY club had a comparison: TVC attenuators, two P&G setups as described above, one in a beautiful wood enclosure, wired with Kimber wire with a Shallco selector switch, the other a Savant Audio design built in a one-piece, solid machined block of Delrin (!) using multiple runs of Cardas Litz wire between each terminal and costing quite a lot of money. We also compared a very good (Goldpoint, maybe?) stepped attenuator with some high quality resistors, also homebrew. Compared in two systems of very, very high quality. The Savant and my Lightspeed clone were close. The Savant had a tiny bit better high frequency resolution, the LDRs had a midrange to die for. Which would you prefer? Up to you, your ear/brain and musical preferences. To me, the LDR was the clear winner.
The other line stages compared were not bad by any means, they were all excellent. The TVC was bottom of the bunch. The guy who built the TVC actually sold his Goldpoint stepped attenuator (that he built) and was surprised to hear that when compared to the TVC he built and kept (the reason he sold the Goldpoint), the stepped attenuator was better than the TVC.
The P&G faders in the gorgeous wood chassis with Kimber wire sounded a bit colored compared to the unit with Cardas in Delrin. You wouldn't think wire and chassis material made any difference at all, especially in a passive. But hearing was believing. If looks meant anything, the wood chassis won.
Again, I had no skin in the game. I planned to build a twin P&G fader attenuator. I already paid the money and bought the parts. Built the LDR unit after hearing good words about one from a trusted friend. It was so cheap, why not try it? Blew me away.
Stuart
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The only hurdle before becomming a true consumer product is control and channel matching.
For us in the DIY game it's ok to match components and fiddle with the tiny details.
To become accepted by the crowd I think there must be a ready solution to get the match without doing the actual matching.
Myself I'm working on the case at the moment. I'm going to try and CNC the front and back plate for the enclosure.
The matching is not a problem. If you look at the best high end systems, they spend a lot of time matching the components - from Speakers to power amps to pre-amps. One of the claims to fame of the FM Acoustics is how much time they spend matching the components. In fact even the passive components are sometimes hand trimmed to meet the close tolerances required.
Would be really interested in seeing what you do with front and back CNC'ed plates.
Dartzeel is already using LDR's in the pre-amp - $26k for the pre-amp. Melos uses it too. I don't know the price.
I missed the Silver TVC on Audiogon. They are hard to come by. I believe the silver TVC by virtue of the silver alone will provide some sonic differences. The fun is probably going to be in the chase, I think we all know the answer to which will be the most neutral, given all things equal.
In this forum the most important thing, I think, is that building a Lightspeed is probably the EASIEST AND MOST REWARDING project on the entire DIY site.
I may be slightly biased
Uriah
From all the problems I see in this forum on building lightspeed and other variants of the DIY LDR VC, I have to say the easiest LDR volume control to build is the WarpSpeed. At the risk of drawing the ire of the lightspeed owners, I have found Warpspeed to have full control from complete silence to full volume. I also have it in a fully BALANCED circuit with only a single single gang pot controlling 8 LDR's, in 4 matched pairs. No loudness issues, no matching problems (so far), and I have long cables - over 10 ft in total from the source to the power amp. I would suggest you guys try this out, especially they ones having all the problems. Talk about easy to set up!! no trimers, less wiring and the LDR's are directly soldered on the connectors.
If I can get the apple remote to work, I will let you know the schmatics for that. Just ordered all the parts and have not started the work. It is a kludge
from all the other work done on the DIY forums on the internet but I hope to refine it.
If a lightspeed owner wants complete silence then a relay to ground will do the trick. Mute.
If a lightspeed owner wants lower min volume then they can take a 100k trimmer and use it as a variable resistor. Put in from the line feeding the series LDRs LED to ground. Adjust to taste. The lower the resistance then the higher the max resistance on the series LDR. This resistor wont effect most resistances much until the LDRs is into higher resistances anyway, so the Rtot wont change a lot simply because of the trimmer until it is required to which is when there is hardly any power going to the LDR at all at which point the amount of power going to ground via the trimmer is large compared to that feeding through to the LDR and so the LDR goes even higher in resistance when volume is turned down all the way and voila, you have nearly zero volume.
Uriah
If a lightspeed owner wants lower min volume then they can take a 100k trimmer and use it as a variable resistor. Put in from the line feeding the series LDRs LED to ground. Adjust to taste. The lower the resistance then the higher the max resistance on the series LDR. This resistor wont effect most resistances much until the LDRs is into higher resistances anyway, so the Rtot wont change a lot simply because of the trimmer until it is required to which is when there is hardly any power going to the LDR at all at which point the amount of power going to ground via the trimmer is large compared to that feeding through to the LDR and so the LDR goes even higher in resistance when volume is turned down all the way and voila, you have nearly zero volume.
Uriah
Ah, when I said consumer product I was thinking about the budget market, not the high end segment.
And yeah, I'm doing a balanced version as well.
The case is nothing special really. I just found a extruded aluminum case lying around and decided to be cheap. Instead of buying a new case I'll fix the end plates for free.
Two knobs at the front, Balance and Volume. Four XLR connectors in the back, nothing fancy. AC wall wart with local regulation and ccs for the LDR's.
And yeah, I'm doing a balanced version as well.
The case is nothing special really. I just found a extruded aluminum case lying around and decided to be cheap. Instead of buying a new case I'll fix the end plates for free.
Two knobs at the front, Balance and Volume. Four XLR connectors in the back, nothing fancy. AC wall wart with local regulation and ccs for the LDR's.
George, Maybe you should have had your coffee this morning. I know that keeps the grumpys away from me.
Pubul57, yes it makes a remarkable difference. I love any implementation of LDRs. They sound really good just about no matter what. The only time I can say they sounded bad was with 6V through the resistor side of them.
Things that make improvements are : Ultra quiet supply (skip the switching supplies), use current sources to power them, use a lot of capacitance around the regulators, snub the LED side of the LDRs with 10-100uf (not more) and a small film cap, use as low of a Rtot as you can manage ( I dont think this goes for just LDRs. Any attenuator with a low output impedance sounds better than the alternative)
If this is your first try at LDRs then build George's circuit just exactly how it is. It is remarkable and it is easy, it is proven and it works. Then if you feel the need to tweak you can start with more capacitance and snubbing which will both yield great results. Some people have used Salas shunt regulator to power the LDRs and have really enjoyed the results so really you have a huge amount of options when powering LDRs but I strongly encourage you to try the circuit that this thread is about first. You cant go wrong. Its the gold standard by which any other implementation will be compared.
Uriah
Pubul57, yes it makes a remarkable difference. I love any implementation of LDRs. They sound really good just about no matter what. The only time I can say they sounded bad was with 6V through the resistor side of them.
Things that make improvements are : Ultra quiet supply (skip the switching supplies), use current sources to power them, use a lot of capacitance around the regulators, snub the LED side of the LDRs with 10-100uf (not more) and a small film cap, use as low of a Rtot as you can manage ( I dont think this goes for just LDRs. Any attenuator with a low output impedance sounds better than the alternative)
If this is your first try at LDRs then build George's circuit just exactly how it is. It is remarkable and it is easy, it is proven and it works. Then if you feel the need to tweak you can start with more capacitance and snubbing which will both yield great results. Some people have used Salas shunt regulator to power the LDRs and have really enjoyed the results so really you have a huge amount of options when powering LDRs but I strongly encourage you to try the circuit that this thread is about first. You cant go wrong. Its the gold standard by which any other implementation will be compared.
Uriah
I know of no true audiophiles who would be offended by that comment. It's a fundamental principle of the art and the hobby both.
And the other point of view is there is are much more elegant solutions out there, with less components that will get absolute results without adding relays, trimmers, resistors or any other components just to get "nearly there" results. KISS. KISS.
Time to move from the bi-plane to the jet plane..... If you would excuse my bluntness... or not.
On power supply's. Adding a choke really improves a power supply ripple. Since the current draw is sufficiently small, this is not too expensive a proposition.
The real elegant solution would be a precision made LDR with not only unit-to-unit consistency, but adding an illuminator less responsive to micro-current levels, eliminating the need for all the filtering and regulation. If there was a demand I'm sure the semi-market would produce it, but our collective needs don't even peak their interest.
I'm quite satisfied with Silonex. I have matched quite a few and just 2 units so far I found that retain some resistance even after power on the LEDs was removed. Battery power powers my 'ship...pure dc and very quiet.
Battery power is the best most purest form of powering the Lightspeed bar none.
During A/B listening test with a dozen "golden eared Audiophiles" it was very hard to tell the difference between the battery or the supplied wall wart on the production Lightspeed Attenuator.
I did measurements (high end Tektonics Scope) and the supplied wall wart produced no more than 200uV!! (that's not millivolts) of noise on the Lightspeed's output, this is undetectable to the human ear, and the reason why in the A/B test the difference was not detectable.
Yet as with all Audiophiles myself included, we all thought there was a very very slight preference for the battery, yet no one could say why, it was that small.
So the motto is, don't waste time money and effort on the power supply, a good linear 12vdc regulated wall wart with a secondary 5vdc regulated power supply as I've posted is more than adequate to get the best out of the Lightspeed "KISS"
Cheers George