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Old 25th February 2011, 06:30 PM   #4021
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Default 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.
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Old 25th February 2011, 06:37 PM   #4022
udailey is online now udailey  United States
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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
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Old 26th February 2011, 12:33 PM   #4023
ua100k is offline ua100k  United States
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Default LDR vs POT

Quote:
Originally Posted by kacernator View Post
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.

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.
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Old 27th February 2011, 01:47 PM   #4024
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Somewhat better.
120r for the shunt resistors
80k for the series resistors.
Lowered the output of the dac to 1.5v
50k pot for balance.
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Old 8th March 2011, 01:38 PM   #4025
udailey is online now udailey  United States
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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
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Old 8th March 2011, 02:01 PM   #4026
markusA is offline markusA  Sweden
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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.
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Old 8th March 2011, 02:02 PM   #4027
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Quote:
Originally Posted by udailey View Post
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
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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Last edited by sepolansky; 8th March 2011 at 02:08 PM.
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Old 8th March 2011, 02:23 PM   #4028
ua100k is offline ua100k  United States
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Quote:
Originally Posted by markusA View Post
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.

Quote:
Originally Posted by udailey View Post
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!
Uriah
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.


Quote:
Originally Posted by udailey View Post

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
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.
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Old 8th March 2011, 02:33 PM   #4029
udailey is online now udailey  United States
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Mark
Dont keep us in the dark about your case Would love to see it.
Uriah
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Old 8th March 2011, 02:39 PM   #4030
udailey is online now udailey  United States
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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
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