Big time on this weekend
Hi guys,
The coming weekend will be the time for my lightspeed passive attenuator to meet with those big names. The set up will be as follow:
Wadia CD player
Clear audio interconnect
Preamps which include my lately finished lightspeed attenuator, Convergent SL-1 signature, Marantz 7, Audio Note M7 and Jadis SP200.
Audio quest clear to poweramp
Power amplifer Jadis JA 80
Speakers ATC 100
No DAC will be used and one thing for sure there will be lots of bullets flying around. Ten to eleven pairs of good ears will join and hope they'd bring lots of wine along so to make this weekend a cheerful one.
Hi guys,
The coming weekend will be the time for my lightspeed passive attenuator to meet with those big names. The set up will be as follow:
Wadia CD player
Clear audio interconnect
Preamps which include my lately finished lightspeed attenuator, Convergent SL-1 signature, Marantz 7, Audio Note M7 and Jadis SP200.
Audio quest clear to poweramp
Power amplifer Jadis JA 80
Speakers ATC 100
No DAC will be used and one thing for sure there will be lots of bullets flying around. Ten to eleven pairs of good ears will join and hope they'd bring lots of wine along so to make this weekend a cheerful one.
Buffer?
Hi guy's, OK so I now have matched pairs and I'm finally going to build this thing!!!
A question if I may about the buffer introduced by Nelson since I last visited this thread.
I'm going to pop this in after my CDP but I want to bi-amp and split the source into two T-amps. This begs for a buffer in there somewhere so which version should I put in to drive two sets of outputs?
Any help would be very much appreciated.
Thanks
Lee
Hi guy's, OK so I now have matched pairs and I'm finally going to build this thing!!!
A question if I may about the buffer introduced by Nelson since I last visited this thread.
I'm going to pop this in after my CDP but I want to bi-amp and split the source into two T-amps. This begs for a buffer in there somewhere so which version should I put in to drive two sets of outputs?
Any help would be very much appreciated.
Thanks
Lee
would someone be so kind as to describe how this particular version of Nelson's version could be extended to control 4 channels for a balanced attenuator:
http://www.diyaudio.com/forums/attachment.php?s=&postid=1521766&stamp=1211904694
Thanks!
http://www.diyaudio.com/forums/attachment.php?s=&postid=1521766&stamp=1211904694
Thanks!
stereolightspeed with buffers by Nelson Pass
Hi,
I am a beginner in diy hobby and have built 2 Lightspeed clone successfully and would like to try my hand at the Buffers.
I am very impressed by the lightspeed and would like to thank Goergehifi for sharing it here .
I need help to interpret the circuit posted in this thread a while ago.
1) Does the LDR 1.2.3.4 refers to the silonex NSL-32SR2 ? If yes how to wire the legs of silonex with reference to the schematic ? How do I indentify the + and _ input ?
2) In the picture, does P2 and P4 refers to the log pot ?
3) Has anybody build the circuit and try it and would like to share the experience and the sound ?
Thanks a lot .
Hi,
I am a beginner in diy hobby and have built 2 Lightspeed clone successfully and would like to try my hand at the Buffers.
I am very impressed by the lightspeed and would like to thank Goergehifi for sharing it here .
I need help to interpret the circuit posted in this thread a while ago.
1) Does the LDR 1.2.3.4 refers to the silonex NSL-32SR2 ? If yes how to wire the legs of silonex with reference to the schematic ? How do I indentify the + and _ input ?
2) In the picture, does P2 and P4 refers to the log pot ?
3) Has anybody build the circuit and try it and would like to share the experience and the sound ?
Thanks a lot .
Krzysztof,
Hope you understand that the last comparison was apple to orange, passive to active.
My lightspeed only even on chamber/light music kind of region, but lost on dynamic amd speed/impact.
I'm still thinking about tweaking my lightspeed with a buffer which was designed by NP. Hope the buffer would give some life to my lightspeed.
Hope you understand that the last comparison was apple to orange, passive to active.
My lightspeed only even on chamber/light music kind of region, but lost on dynamic amd speed/impact.
I'm still thinking about tweaking my lightspeed with a buffer which was designed by NP. Hope the buffer would give some life to my lightspeed.
hi, thanks george for sharing us this simple but very clever circuit
i have compare it with a LEBEN Rs28 preamp , on a pair of electrocompaniet AW180
(220K input impédance 1V ) and i think i will sell my wonderfull Leben because the ugly black box i built with lightspeed in it, is much more natural and peacefull , just let the music flow. sure the leben 's got a better midrange and better dynamics but i don't care.. the lightspeed is so much better in all other aspect..
who wants a Leben?
i have compare it with a LEBEN Rs28 preamp , on a pair of electrocompaniet AW180
(220K input impédance 1V ) and i think i will sell my wonderfull Leben because the ugly black box i built with lightspeed in it, is much more natural and peacefull , just let the music flow. sure the leben 's got a better midrange and better dynamics but i don't care.. the lightspeed is so much better in all other aspect..
who wants a Leben?
Albertli: Quote> My lightspeed only even on chamber/light music kind of region, but lost on dynamic amd speed/impact.< end quote
If you are still having as you put it dynamic/speed/impact problems Albertli. Then you have a impedance drive problem, as these problems you mention are just three of the Lightspeeds hallmarks (strenghts) if all is fine.
Your problem is almost certain to be the output impedance of the tube output stage of the Audio Note dac you have not being able to drive the Lightspeed because of
A: The tube output impedance is too high >1kohm
B: The tube output stage is too low in voltage drive <2v
C: Or a combination of both
From your circuit of your poweramp this looks fine at 1mohm, and so long as the sensitivity (gain) is < 2v to clip, this is fine also.
This can be ascertained by the position of the Lightspeeds (as I designed it) control pot being at the 12o'clock region for normal loud listening level, if it is at 3o'clock for normal level then the dac has low output <2v or the power amp has low sensitivity (gain) >2v to clip.
Cheers George
If you are still having as you put it dynamic/speed/impact problems Albertli. Then you have a impedance drive problem, as these problems you mention are just three of the Lightspeeds hallmarks (strenghts) if all is fine.
Your problem is almost certain to be the output impedance of the tube output stage of the Audio Note dac you have not being able to drive the Lightspeed because of
A: The tube output impedance is too high >1kohm
B: The tube output stage is too low in voltage drive <2v
C: Or a combination of both
From your circuit of your poweramp this looks fine at 1mohm, and so long as the sensitivity (gain) is < 2v to clip, this is fine also.
This can be ascertained by the position of the Lightspeeds (as I designed it) control pot being at the 12o'clock region for normal loud listening level, if it is at 3o'clock for normal level then the dac has low output <2v or the power amp has low sensitivity (gain) >2v to clip.
Cheers George
George,
I forgot the DAC for quite some time when playing with the lightspeed. We even just hooked up the CD player when compare.
I admit that there should be something wrong with my lightspeed, but not your design. I'm still struggling to chase the problem I had and try everything I know to tweak the attenuator to it's best. I hope I could find out what went wrong.
I forgot the DAC for quite some time when playing with the lightspeed. We even just hooked up the CD player when compare.
I admit that there should be something wrong with my lightspeed, but not your design. I'm still struggling to chase the problem I had and try everything I know to tweak the attenuator to it's best. I hope I could find out what went wrong.
Remote control for LDR volume control
Rohan from France has just e-mailed me regarding the remote control of the Lightspeed. Unfortunately my reply has been returned as undelivered for some reason. I am assuming that you will be monitoring this thread, Rohan, so I have copied your message and my reply here.
Hi, i have just finsh my first lightspeed attenuator and i'm
very happy with the result. but i'm interested now to remote control it . do you have
remote control module to sell yet?
and what is the constant current voltage advantage with the lightspeed attenuator? do
you have a schema for it?
thanks.
rohan from FRANCE
Hi Rohan,
Thank you for your interest in a remote control for the Lightspeed. I am afraid that no interest has been shown on the Lightspeed forum thread and only three enquiries have reached me so far. This is not enough to warrant the time and cost of preparing a set of modules for the control of the Lightspeed and the hand held controller module. With this in mind, and in the spirit of George's decision to allow DIY enthusiasts to use his design, I have posted a schematic for my voltage controlled current source, that I use to drive the LDR LEDs, on the forum thread in post number 1387 together with some general advice on setting up and interfacing with a remote control kit. Experienced constuctors should be able to adapt this successfully to their needs.
Using current drive for the LEDs via a voltage controlled current source (VCCS) has proved to be much less drifty than voltage driven potentiometers in my system. This improves image precision. Also the balance function of the Dallas potentiometer reduces the matching burdon with the LDRs. Others have commented on improved sound quality with current drive and my own experience backs this up. This is likely to be noise related as random noise in the current flow to the LED would cause a randomly shifting operating point. With a low noise power supply the VCCS is quiet. Mechanical potentiometers can be noisy with DC voltage across them and age tends to make this worse. Using the VCCS also makes it easy to interface with the remote control system.
I do understand that not everyone would feel confident at dealing with this project by themselves, from the information I have posted, and that built and tested modules would make life easy for all concerned. If you want to see these modules become available, make yourself known by posting on the Lightspeed thread.
Regards
Paul
Rohan from France has just e-mailed me regarding the remote control of the Lightspeed. Unfortunately my reply has been returned as undelivered for some reason. I am assuming that you will be monitoring this thread, Rohan, so I have copied your message and my reply here.
Hi, i have just finsh my first lightspeed attenuator and i'm
very happy with the result. but i'm interested now to remote control it . do you have
remote control module to sell yet?
and what is the constant current voltage advantage with the lightspeed attenuator? do
you have a schema for it?
thanks.
rohan from FRANCE
Hi Rohan,
Thank you for your interest in a remote control for the Lightspeed. I am afraid that no interest has been shown on the Lightspeed forum thread and only three enquiries have reached me so far. This is not enough to warrant the time and cost of preparing a set of modules for the control of the Lightspeed and the hand held controller module. With this in mind, and in the spirit of George's decision to allow DIY enthusiasts to use his design, I have posted a schematic for my voltage controlled current source, that I use to drive the LDR LEDs, on the forum thread in post number 1387 together with some general advice on setting up and interfacing with a remote control kit. Experienced constuctors should be able to adapt this successfully to their needs.
Using current drive for the LEDs via a voltage controlled current source (VCCS) has proved to be much less drifty than voltage driven potentiometers in my system. This improves image precision. Also the balance function of the Dallas potentiometer reduces the matching burdon with the LDRs. Others have commented on improved sound quality with current drive and my own experience backs this up. This is likely to be noise related as random noise in the current flow to the LED would cause a randomly shifting operating point. With a low noise power supply the VCCS is quiet. Mechanical potentiometers can be noisy with DC voltage across them and age tends to make this worse. Using the VCCS also makes it easy to interface with the remote control system.
I do understand that not everyone would feel confident at dealing with this project by themselves, from the information I have posted, and that built and tested modules would make life easy for all concerned. If you want to see these modules become available, make yourself known by posting on the Lightspeed thread.
Regards
Paul
sorry paul , i have my adress mail not yet updated ..it's done now. thanks for the schema , i'm a newbee in DIY so it seems a litle
more complicate to build than the George original lightspeed.
do you have a version just with the VCC and without the remote control option?
anyway i think if one day you will
build a little serie of it i will be glad to order one from you..
you say that sometimes pots are noisy with some DC on it, is it the same with all pots,
plastics, carbon, or stepped attenuator?
thanks to you and George , the lightspeed attenuator is my first diy project
and surrely not the last one
Remote control for the Lightspeed
Hi Rohan,
This remote control VCCS circuit was developed originally purely for my own use. I had envisaged the remote control system as a simple modular arrangement. This makes it easier to fit in confined spaces. I have, in fact, already produced a circuit layout for the voltage controlled current source section and I am about half way through the infra-red handset board layout. Once I have finished this and the infra-red receiver board I am intending to make two sets of prototype printed circuit boards. One set for installation in my system and one set that I promised for George to try in his system.
George may feel the need to adjust the contour of the volume control with the VCCS to match his passive Lightspeed more closely. My system is completely different to his. I use fets and valves in the various signal processing/buffering circuits of my system and the volume control in my system is a higher impedance type than the Lightspeed. I also use the series resistor/shunt LDR configuration, which only requires one voltage controlled current source per channel. The contour on my system volume control is matched to my system requirements. Adapting my original circuit, to provide the two opposing voltage controlled current sources required per channel for the Lightspeed, will require some resistor adjustment in the VCCS circuitry to suit your system volume contour needs. As I do not have the Lightspeed configuration in my system, at the moment, and systems vary condiderably, I can’t advise on actual resistor values for achieving this. It should be relatively easy to do this by ear. It is likely that I will experiment with the Lightspeed configuration, for the higher impedance circuitry in my system, when time allows.
Making printed circuit boards is messy and time consuming so I feel little incentive to do this on a commercial basis. Once I have verified that there are no mistakes on the board layouts, the CAD files will be available for PCB manufacture. I would need to order 25 sets to get a reasonable price for this production run. To be fair, I would not wish to fund this up-front and then find I am left with 24 sets of printed circuit boards in my stock room. The three modules for hand-held remote, receiver and VCCS are unlikely to cost more than £100 built and tested. If I see some more interest I will do a more accurate costing so you know the full financial implications.
Pots with DC across them can be very noisy when rotated. I would find this annoying. The DC also produces additional thermal noise, over and above that caused by the AC signal, across the impedance of the control. Carbon tracks tend to be noisier than conductive plastic. Stepped attenuators should be a better option. The DS1802 I used in the VCCS is essentially an electronic stepped attenuator. Fortunately it is relatively quiet. I have added noise filtering between the pot wiper and the inputs to the TL074 on the VCCS board layout to reduce residual noise. The TL074 is the quad version of the TL071 and I used this to enhance thermal matching of the current sources thus reducing drift on the LDR volume settings. In practice, in the real world on the test bench, the VCCS circuit showed no noticable drift over a three day test period. Constructors have noticed that filtering the drive current to the LED gives an audible improvement so check back through the thread for advice on this. I have allowed space for filter capacitors on the VCCS board.
I am pleased that you have enjoyed the results of your first DIY project, Rohan. George's Lightspeed is a great first project because it is so elegantly simple and the results far outweigh the expense of procurement. Even if you have to go through 20 LDRs to get a match it is still worth every penny and all the effort required for matching.
Regards
Paul
Hi Rohan,
This remote control VCCS circuit was developed originally purely for my own use. I had envisaged the remote control system as a simple modular arrangement. This makes it easier to fit in confined spaces. I have, in fact, already produced a circuit layout for the voltage controlled current source section and I am about half way through the infra-red handset board layout. Once I have finished this and the infra-red receiver board I am intending to make two sets of prototype printed circuit boards. One set for installation in my system and one set that I promised for George to try in his system.
George may feel the need to adjust the contour of the volume control with the VCCS to match his passive Lightspeed more closely. My system is completely different to his. I use fets and valves in the various signal processing/buffering circuits of my system and the volume control in my system is a higher impedance type than the Lightspeed. I also use the series resistor/shunt LDR configuration, which only requires one voltage controlled current source per channel. The contour on my system volume control is matched to my system requirements. Adapting my original circuit, to provide the two opposing voltage controlled current sources required per channel for the Lightspeed, will require some resistor adjustment in the VCCS circuitry to suit your system volume contour needs. As I do not have the Lightspeed configuration in my system, at the moment, and systems vary condiderably, I can’t advise on actual resistor values for achieving this. It should be relatively easy to do this by ear. It is likely that I will experiment with the Lightspeed configuration, for the higher impedance circuitry in my system, when time allows.
Making printed circuit boards is messy and time consuming so I feel little incentive to do this on a commercial basis. Once I have verified that there are no mistakes on the board layouts, the CAD files will be available for PCB manufacture. I would need to order 25 sets to get a reasonable price for this production run. To be fair, I would not wish to fund this up-front and then find I am left with 24 sets of printed circuit boards in my stock room. The three modules for hand-held remote, receiver and VCCS are unlikely to cost more than £100 built and tested. If I see some more interest I will do a more accurate costing so you know the full financial implications.
Pots with DC across them can be very noisy when rotated. I would find this annoying. The DC also produces additional thermal noise, over and above that caused by the AC signal, across the impedance of the control. Carbon tracks tend to be noisier than conductive plastic. Stepped attenuators should be a better option. The DS1802 I used in the VCCS is essentially an electronic stepped attenuator. Fortunately it is relatively quiet. I have added noise filtering between the pot wiper and the inputs to the TL074 on the VCCS board layout to reduce residual noise. The TL074 is the quad version of the TL071 and I used this to enhance thermal matching of the current sources thus reducing drift on the LDR volume settings. In practice, in the real world on the test bench, the VCCS circuit showed no noticable drift over a three day test period. Constructors have noticed that filtering the drive current to the LED gives an audible improvement so check back through the thread for advice on this. I have allowed space for filter capacitors on the VCCS board.
I am pleased that you have enjoyed the results of your first DIY project, Rohan. George's Lightspeed is a great first project because it is so elegantly simple and the results far outweigh the expense of procurement. Even if you have to go through 20 LDRs to get a match it is still worth every penny and all the effort required for matching.
Regards
Paul
thanks for all for the moment i do some test with the power supply
of the L.A and i use four BIg 10000uf elna cerafine caps with a very silent regulator
from mikrel with 1uf bg nx non polar cap and 0.01MKP decoupling caps. for the 5V
but the better tweak i have found with my config was to put TWO decoupling caps after the volume pots one for the + and the other for the - i have try 47uf with success
the sound seems to be cleaner than before with tight bass .. ( perhaps it helps in case
of a noisy carbon pots like mine??)
for the moment i do some test with the power supplyof the L.A and i use four BIg 10000uf elna cerafine caps with a very silent regulator
from mikrel with 1uf bg nx non polar cap and 0.01MKP decoupling caps. for the 5V
but the better tweak i have found with my config was to put TWO decoupling caps after the volume pots one for the + and the other for the - i have try 47uf with success
the sound seems to be cleaner than before with tight bass .. ( perhaps it helps in case
of a noisy carbon pots like mine??)