I could have swore it was an "100K Audio Taper" pot - which is a Log Pot correct?
If it is a Linear pot, I guess I can try a Law Fake 10K resistor across the wiper and ground on both gangs...
If all is well I may update to the single 100K log pot (so no chance of channel mismatch on pot side)
If it is a Linear pot, I guess I can try a Law Fake 10K resistor across the wiper and ground on both gangs...
If all is well I may update to the single 100K log pot (so no chance of channel mismatch on pot side)
OK, I confirmed that the Pot I am using is indeed a 100k Log pot.
I reconnected the pot so I am using just the one side of the Dual pot per last schematic and it works fine. I need to do some more critical listening and may have to recalibrate the channels since I changed things around a bit...so far looks/sounds promising...
I reconnected the pot so I am using just the one side of the Dual pot per last schematic and it works fine. I need to do some more critical listening and may have to recalibrate the channels since I changed things around a bit...so far looks/sounds promising...
What do you guys make of this????
I don't know what to make of it, remember the Dartzel NHB-18NS preamp that I posted back on page 69, the designer Hervé Delétraz, where he stated that the reason for the great sound out of this pre was mainly due to the LDR (Lightspeed) volume control, well the links to this seem to have disappeard of Dartzel website.
http://www.dartzeel.com/pages_E/NHB18_info_E.html
And now Stereophile have released the review free to read on their website,
http://www.stereophile.com/solidpreamps/607dart/
but again no mention of the LDR (Lightspeed) volume control that I can see.
6 Moons review is still there
http://www.6moons.com/audioreviews/dartzeel2/preamp.html
I have also noticed that the so called patent application on the volume control still has not been lodged as Hervé Delétraz said in that interview he had made.
Cheers George
I don't know what to make of it, remember the Dartzel NHB-18NS preamp that I posted back on page 69, the designer Hervé Delétraz, where he stated that the reason for the great sound out of this pre was mainly due to the LDR (Lightspeed) volume control, well the links to this seem to have disappeard of Dartzel website.
http://www.dartzeel.com/pages_E/NHB18_info_E.html
And now Stereophile have released the review free to read on their website,
http://www.stereophile.com/solidpreamps/607dart/
but again no mention of the LDR (Lightspeed) volume control that I can see.
6 Moons review is still there
http://www.6moons.com/audioreviews/dartzeel2/preamp.html
I have also noticed that the so called patent application on the volume control still has not been lodged as Hervé Delétraz said in that interview he had made.
Cheers George
I don't mean to be disparaging, but it seems to me that the Lightspeed is simply an implementation of the level control as seen on the Silonex website. Pretty much a copy of the series/shunt design that they suggest for their parts.
So OK you have been kind enough to draw our attention to how good the Silonex parts sound, but it does not seem as if you have come up with anything particularly original. OK so you say that you had been experimenting with LDRs for years, but as far as I am aware, so have other people. But the first version of the Lightspeed used a Silonex part, right?
So why the fuss about whether anyone else is using the same idea. Silonex surely want as many people as possible to use their parts in the way that they meant to be used. (I am thinking here of the comments about audio synthesis for example, or indeed, the Dartzel)
I know that this sort of thing is common in audiophile-land - after all, look at all the fuss made over the "gain clone" which after all is pretty much wiring up a chip according to the Nat Semi datasheet.
So OK you have been kind enough to draw our attention to how good the Silonex parts sound, but it does not seem as if you have come up with anything particularly original. OK so you say that you had been experimenting with LDRs for years, but as far as I am aware, so have other people. But the first version of the Lightspeed used a Silonex part, right?
So why the fuss about whether anyone else is using the same idea. Silonex surely want as many people as possible to use their parts in the way that they meant to be used. (I am thinking here of the comments about audio synthesis for example, or indeed, the Dartzel)
I know that this sort of thing is common in audiophile-land - after all, look at all the fuss made over the "gain clone" which after all is pretty much wiring up a chip according to the Nat Semi datasheet.
Go back 35 years ago then you have when I started it, and not with Silonex parts, read the thread from the begining, and you will be better informed as to the history.
And the very first version (35 years ago) of the Lightspeed, I built out of cds cells I removed from light meters of old broken down cameras.
Cheers George
And the very first version (35 years ago) of the Lightspeed, I built out of cds cells I removed from light meters of old broken down cameras.
Cheers George
George, yes I had read the whole thread. I noted that you say you have been doing this for a long time, and can prove it. (Care to prove it?)
You also mention that the first Lightspeed prototype is about 5 years old.
I also note that the very first post shows a circuit diagram lifted from the Silonex website.
Also I saw this:
How would Audio Synthesis have known that you were doing this?
It seems that there were people doing this before you were, even if you were doing this 35 years ago.
I very much doubt that Datzeel were hoping to get a patent for something that appears on Silonex's website. I think it's more likely that they were thinking of patenting some other aspect of their design.
You also mention that the first Lightspeed prototype is about 5 years old.
I also note that the very first post shows a circuit diagram lifted from the Silonex website.
Also I saw this:
How would Audio Synthesis have known that you were doing this?
It seems that there were people doing this before you were, even if you were doing this 35 years ago.
I very much doubt that Datzeel were hoping to get a patent for something that appears on Silonex's website. I think it's more likely that they were thinking of patenting some other aspect of their design.
Haven't you got a life, here are some names, find out yourself.
No1: George Cronin Master violin teacher at the Conservatorium of Music Sydney
No2: Otto Major the only person who has been completely re-diaphraming/rebuilding Quad ESL57 since they were first released, recomended by the late Peter J. Walker
No3: Elson Silver Australia's primo Tube amp builder
No4: Christian Feillafe Australia first pure Class A stereo amp manufacture, also in partnership with Otto Major in the Quad 57 program
No5: Steven Dertatz my mentor from the age of 16 and Australia's and probably the world foremost authority on Photo Electronics
And a host of others which some are no longer with us
You realy don't do your homework before frothing forth.
Quote>I very much doubt that Datzeel were hoping to get a patent for something that appears on Silonex's website. I think it's more likely that they were thinking of patenting some other aspect of their design.<Quote
Herve Delaratz interview
Quote>Q: What is wrong with conventional volume controls?
A: You lose something. I use a system that varies resistance with light. However, until all the patents are in place, I would prefer not to specify the details.<Quote
No1: George Cronin Master violin teacher at the Conservatorium of Music Sydney
No2: Otto Major the only person who has been completely re-diaphraming/rebuilding Quad ESL57 since they were first released, recomended by the late Peter J. Walker
No3: Elson Silver Australia's primo Tube amp builder
No4: Christian Feillafe Australia first pure Class A stereo amp manufacture, also in partnership with Otto Major in the Quad 57 program
No5: Steven Dertatz my mentor from the age of 16 and Australia's and probably the world foremost authority on Photo Electronics
And a host of others which some are no longer with us
You realy don't do your homework before frothing forth.
Quote>I very much doubt that Datzeel were hoping to get a patent for something that appears on Silonex's website. I think it's more likely that they were thinking of patenting some other aspect of their design.<Quote
Herve Delaratz interview
Quote>Q: What is wrong with conventional volume controls?
A: You lose something. I use a system that varies resistance with light. However, until all the patents are in place, I would prefer not to specify the details.<Quote
The quote is from the interview that you just pointed out had been removed, right? Well that's why I could not check that out (as I failed to look that up when it was available).
OK so I went to the Dartzeel website. If you read about their preamp you find that there are many different aspects they claim make their device sound so good.
They claim that their various "circuits are patented", not specifically the volume control.
Now when it comes to the volume control they say:
So clearly they are using a similar thing to what you are. But whereas the Lightspeed is basically the design from the Silonex website, they have produced a design that uses a "dedicated processor" to produce a series of 192 steps providing a dynamic range of 9dB.
Given the problems that you have noted of getting these devices to match, I suspect that they may well have come up with a clever way of controlling these devices such that they (a) track together properly and (b) give a much larger dynamic range.
If they have, then this may well be worthy of a patent.
Hardly "not doing my homework". And btw, "frothing forth" is not what I was doing. I was commenting. That sort of language says a lot more about you than it does about me.
Once again the quote directly from the Hervé Delétraz 6 Moons interview.
Q: What is wrong with conventional volume controls?
A: You lose something. I use a system that varies resistance with light. However, until all the patents are in place, I would prefer not to specify the details.
End of discussion
Q: What is wrong with conventional volume controls?
A: You lose something. I use a system that varies resistance with light. However, until all the patents are in place, I would prefer not to specify the details.
End of discussion
Re: Re: Can work, with volume pot impedance
As a user of DACT passive attenuator, I always like the idea of less component. Well....it will be more than excellent if I can keep it that way for the open baffle spekaer I hope to build.
The speaker I have in mind will be something like NaO but using all passive components and driven by 2 power amp and a sub. I already have the 2 power amp and the sub amp so I am pretty keen on this. Active seems to be the way to go but it is a bit compex for my simple mind
and if I can do it with lightspeed ... it will be one hell of a system. 
Well, the input impedance of the power amp (AKSA) are 47K each and the sub amp is 30K. I Know this is a big ask for the passive lightspeed but since some are saying the lightspeed can be loud, I wonder I can do this with 50K log pot on the lightspeed or some mod on the wiring.
Edit: correct spelling.
georgehifi said:
As a user of DACT passive attenuator, I always like the idea of less component. Well....it will be more than excellent if I can keep it that way for the open baffle spekaer I hope to build.
The speaker I have in mind will be something like NaO but using all passive components and driven by 2 power amp and a sub. I already have the 2 power amp and the sub amp so I am pretty keen on this. Active seems to be the way to go but it is a bit compex for my simple mind
and if I can do it with lightspeed ... it will be one hell of a system. Well, the input impedance of the power amp (AKSA) are 47K each and the sub amp is 30K. I Know this is a big ask for the passive lightspeed but since some are saying the lightspeed can be loud, I wonder I can do this with 50K log pot on the lightspeed or some mod on the wiring.
Edit: correct spelling.
Re: Re: Re: Can work, with volume pot impedance
It may be possible to change the Aksa's to 150k, I would ask Hugh first, if they are fet input it should be ok, even if they are not, as I have a biamp setup and my amps at the moment are bipolar input and I have changed them to 150k, safe so long as they are never switched on without the Lightspeed attached, you see it makes the input think it has a 7k on it, without the Lightspeed on it sees only the 150k and the dc offset can get high, but that will never be allowed to happen in my case.
As far as the sub amp goes the majority are usually fet input amps so it safe to up the input to 150k, but make sure first.
Cheers George
SamL said:
As a user of DACT passive attenuator, I always like the idea of less component. Well....it will be more than excellent if I can keep it that way for the open baffle spekaer I hope to build.
The speaker I have in mind will be something like NaO but using all passive components and driven by 2 power amp and a sub. I already have the 2 power amp and the sub amp so I am pretty keen on this. Active seems to be the way to go but it is a bit compex for my simple mind
Well, the input impedance of the power amp (AKSA) are 47K each and the sub amp is 30K. I Know this is a big ask for the passive lightspeed but since some are saying the lightspeed can be loud, I wonder I can do this with 50K log pot on the lightspeed or some mod on the wiring.
Edit: correct spelling.
It may be possible to change the Aksa's to 150k, I would ask Hugh first, if they are fet input it should be ok, even if they are not, as I have a biamp setup and my amps at the moment are bipolar input and I have changed them to 150k, safe so long as they are never switched on without the Lightspeed attached, you see it makes the input think it has a 7k on it, without the Lightspeed on it sees only the 150k and the dc offset can get high, but that will never be allowed to happen in my case.
As far as the sub amp goes the majority are usually fet input amps so it safe to up the input to 150k, but make sure first.
Cheers George
A "luxury" way of controlling the attenautor and get perfect tracking would be to use DACs to provide the control voltages and use a prom to store the curves. Then one can adjust the prom data between the channels to achieve a perfect match. As a bonus we get digital input to control the attenautor.
Christer said:
That's the idea behind the effort that will (probably) be made on a group project based on the lightspeed principle on the italian diy forum www.audiofaidate.it
The concept is then extended to contactless source switching and auto-calibration of the currents to the elements to allow the use of unmatched devices.
Cheers
Andrea
Hey Bear - your the Backer's Bakery guy right? Good to hear from you again. I pass there every day dropping my kids off at daycare...if you ever see a brown Land Rover honking his horn in out in front at 7:00 am in the morning, well don't throw any eggs at me!
The Lightspeed is complete with a 100k Audio Taper jobbie from ratshack and works just fine. It was slapped together and placed in a clear plastic box from IKEA. This first one was an attempt to check out all the buzz from DIYAudio, and my next, more formal one will be a little more refined.
I had done minimal (and I mean minimal) critical listening of the unit on a point to point gainclone and my UCD400 amp...So far I like. I don't know if it will be replacing my Bottlehead Foreplay III yet on my main UCD system, but will see. As I said earlier, I did a halfassed job matching the LDRs, and compiled a overly basic power supply (19VDC Laptop power supply feeding a 7805 reg with single .1uF cap at input for the 5VDC to unit) and may be the reason the sound seems not as focused and dynamic as the FPIII. Or maybe a burn-in issue?
You have a Circuit board? I am interested. Those fine photo side leads were a nightmare...which is why I did a halfassed matching job in the firstplace....
Georgehifi - Despite the ribbing your currently getting from a fellow member and countryman (?) I again can say I appreciate your efforts and knowledge.
Yep, that's me bakin away when you drive by
I have mine running Pavel's PA03 which has a input buffer which I think is needed for this Preamp with a gainclone.
I have also tried it with a AMP9 from 41Hz and it runs at 50k input impedence and it sounded really good. I believe the UCD has an imput buffer too right? It might be better used with that amp.
I'll send you my email address.
Bear
I have mine running Pavel's PA03 which has a input buffer which I think is needed for this Preamp with a gainclone.
I have also tried it with a AMP9 from 41Hz and it runs at 50k input impedence and it sounded really good. I believe the UCD has an imput buffer too right? It might be better used with that amp.
I'll send you my email address.
Bear
Impedance matching
One comment, on the dynamics and imaging. The LDR's are very hard to match up properly. The tempco is huge, and there is a large hysteresis effect. The resistance readings are far apart depending if the current is increased or decreased. It seems that in time, a couple of hours, they drift closer.
To get the best out of them, I use mismatched pots. Maybe one 5% off from the other. Then hook it up and check the input to ground resistance as the pot is fully rotated. The do the other channel. Then swap the pots to see if this gets closer.
Even after what I considered close matching, the impedance from one channel to the other varied by 10 -20%. By selecting the right pot, both of my clones are now within a couple percent on full rotation.
This impedance measured can have a big effect on lowend response and dynamics. Depending on the souce, too low an impedance will roll off the bass. Too high an impedance will muffle the dynamics. Most commercial passives are 10K. That is a good midpoint. An imbalance in impedance between the channels can effect the imaging also.
Most discplayers, with an output stage. can drive the 7K or so of the Lightspeed. but there are several variable; output impedance of the source, imput impedance of the amplifier, capacitance of the two sets of cables, and finally impedance of the Lightspeed.
So it is easy to see how some find the passive approach difused, muted, rolled off, or just plain lacking. But in the right conditions, the results can be"better than any active stage" as paraphased from someone here.
George
One comment, on the dynamics and imaging. The LDR's are very hard to match up properly. The tempco is huge, and there is a large hysteresis effect. The resistance readings are far apart depending if the current is increased or decreased. It seems that in time, a couple of hours, they drift closer.
To get the best out of them, I use mismatched pots. Maybe one 5% off from the other. Then hook it up and check the input to ground resistance as the pot is fully rotated. The do the other channel. Then swap the pots to see if this gets closer.
Even after what I considered close matching, the impedance from one channel to the other varied by 10 -20%. By selecting the right pot, both of my clones are now within a couple percent on full rotation.
This impedance measured can have a big effect on lowend response and dynamics. Depending on the souce, too low an impedance will roll off the bass. Too high an impedance will muffle the dynamics. Most commercial passives are 10K. That is a good midpoint. An imbalance in impedance between the channels can effect the imaging also.
Most discplayers, with an output stage. can drive the 7K or so of the Lightspeed. but there are several variable; output impedance of the source, imput impedance of the amplifier, capacitance of the two sets of cables, and finally impedance of the Lightspeed.
So it is easy to see how some find the passive approach difused, muted, rolled off, or just plain lacking. But in the right conditions, the results can be"better than any active stage" as paraphased from someone here.
George
Re: Multichannel LDR Preamp
we're trying to do just about the same as a group project here: www.audiofaidate.it/forum/topic.asp?TOPIC_ID=2576
see page 4 for the first draft of the audio circuit with contactless input switch.
Though we were thinking about stereo, all the requirements and solutions (except for the number of channels) would be the same... if you (and/or perhaps someone else) is interested, it would be nice to merge our efforts.
barryblue said:
we're trying to do just about the same as a group project here: www.audiofaidate.it/forum/topic.asp?TOPIC_ID=2576
see page 4 for the first draft of the audio circuit with contactless input switch.
Though we were thinking about stereo, all the requirements and solutions (except for the number of channels) would be the same... if you (and/or perhaps someone else) is interested, it would be nice to merge our efforts.