Guys,
I just ran out of LDRs but ordered more as I have more people that would like matched pairs. My matching was very good and I did listen to each and every pair before they were shipped. Hope more of you would like to listen to this incredible little attenuator. It is by far the best passive I have heard. Was going to hook it up to my B1. Guess I should do that in the next day or two to see what its like. Probably better to leave it as is but then the poor B1 sits there without a use.
George has a heck of a simple design here. You can actually take 2 LDRs and solder them directly to your amp then run power to them and a signal line from your RCA input to the amp chassis. This results in ZERO additional interconnects.
Uriah
I just ran out of LDRs but ordered more as I have more people that would like matched pairs. My matching was very good and I did listen to each and every pair before they were shipped. Hope more of you would like to listen to this incredible little attenuator. It is by far the best passive I have heard. Was going to hook it up to my B1. Guess I should do that in the next day or two to see what its like. Probably better to leave it as is but then the poor B1 sits there without a use.
George has a heck of a simple design here. You can actually take 2 LDRs and solder them directly to your amp then run power to them and a signal line from your RCA input to the amp chassis. This results in ZERO additional interconnects.
Uriah
Lightspeed remote control
Hello Udaily,
I think you have my remote design confused with someone else’s. There is no microprocessor in my design. The DS1802 has all the control logic for the electronic potentiometers internally. There is no need for an external control microprocessor. Why complicate the issue un-necessarily. Also I do not need an LCD readout to tell me how loud the music is, just my ears.
The design brief I set myself was to provide a low cost solution for volume up and volume down with a channel balance function to compensate for any LDR matching discrepancies. There are no complicated programming requirements and all the components are readily available.
Regards
Paul
Hello Udaily,
I think you have my remote design confused with someone else’s. There is no microprocessor in my design. The DS1802 has all the control logic for the electronic potentiometers internally. There is no need for an external control microprocessor. Why complicate the issue un-necessarily. Also I do not need an LCD readout to tell me how loud the music is, just my ears.
The design brief I set myself was to provide a low cost solution for volume up and volume down with a channel balance function to compensate for any LDR matching discrepancies. There are no complicated programming requirements and all the components are readily available.
Regards
Paul
Yeah, must have been a different one. Maybe that "Myth" one that is or did come out recently.
Still interested in your design. I would buy one/some. I have looked into DS1802 a few times but passed because Nelson Pass said it wasnt really worth the trouble but this application is quite different since no sound will pass through it.
Uriah
Still interested in your design. I would buy one/some. I have looked into DS1802 a few times but passed because Nelson Pass said it wasnt really worth the trouble but this application is quite different since no sound will pass through it.
Uriah
matched LDRs
Uriah,
What would it take to match up 20 sets (40 pairs) of LDRs for Paul's kits - they needn't be matched to the outer limits as there is a bit of tolerance with Paul's balance adjustment - an estimate of the cost per set?
Incidently, I used a couple of ZIF sockets and set them up to do 6 LDRs together, and kept the first one continuously as a reference - this makes it 5 times faster and is a check for any variations on power supply, temperature, etc - saves having to go back over them to check for errors.
Paul,
Could you add space on your board for the LDRs, if you haven't already done it, and perhaps a good secondary discrete regulator?
I think if we could tie these ends together like Aleks did in the "Serbian Lightspeed" project, we would get those last few orders for the initial 20 boards filled very quickly.
... Jh
Uriah,
What would it take to match up 20 sets (40 pairs) of LDRs for Paul's kits - they needn't be matched to the outer limits as there is a bit of tolerance with Paul's balance adjustment - an estimate of the cost per set?
Incidently, I used a couple of ZIF sockets and set them up to do 6 LDRs together, and kept the first one continuously as a reference - this makes it 5 times faster and is a check for any variations on power supply, temperature, etc - saves having to go back over them to check for errors.
Paul,
Could you add space on your board for the LDRs, if you haven't already done it, and perhaps a good secondary discrete regulator?
I think if we could tie these ends together like Aleks did in the "Serbian Lightspeed" project, we would get those last few orders for the initial 20 boards filled very quickly.
... Jh
Re: Lightspeed remote control
Hello Paul
I am interested in your boards, but I am a bit confused, earlier you said that we could use your board with a motorized pot as well, now you have another IC and I am not sure if it is still possible. I like the feeling of a pot that i can turn manually and remote controlled.
Thank you for your patience.
maximus said:
Hello Paul
I am interested in your boards, but I am a bit confused, earlier you said that we could use your board with a motorized pot as well, now you have another IC and I am not sure if it is still possible. I like the feeling of a pot that i can turn manually and remote controlled.
Thank you for your patience.
I ordered 25 a while back and have about 20 of those left. Ordered 100 a few weeks ago and have 56 of them left and I just ordered another 100. I could come up with that many pairs in two weeks. I would test the new 100 against the misfits of the leftover 76 and I am sure I could come up with 20 pairs, perhaps more. I can certainly come up with whatever amount we need if there is to be a collaboration.
I also just got a hold of some 5V regulated power supplies that need a wallwart of 7-12VDC. Output 1A. I doubt those are necessary for Paul has he seems to be a heck of a PS designer. But they were a good deal and if anyone wants one along with pairs that can be easily done.
Uriah
I also just got a hold of some 5V regulated power supplies that need a wallwart of 7-12VDC. Output 1A. I doubt those are necessary for Paul has he seems to be a heck of a PS designer. But they were a good deal and if anyone wants one along with pairs that can be easily done.
Uriah
Re: Lightspeed remote control
Hi Paul,
Does the volume automatically drop to 0 (zero) every time the power is shut off. Since there no display indicating the set volume, it is quite important for me to have the volume set to zero from start. With kids around the house, one never know how loud it has been set to.
maximus said:
Hi Paul,
Does the volume automatically drop to 0 (zero) every time the power is shut off. Since there no display indicating the set volume, it is quite important for me to have the volume set to zero from start. With kids around the house, one never know how loud it has been set to.
balanced Lightspeed
Greetings, and thanks to georgehifi for making Lightspeed available. I hope to build the attenuator for balanced line use and noted that Jason in post #1514, instead of using eight LDRs altogether, used only six --three per channel. Two are in series with the signal leads for each channel and one shunts between the leads.
I'd like to find out whether I can use Jason's balanced Lightspeed arrangement without altering my amplifiers. The amps are Atma-Sphere M60s with 4k7 resistors from each input hot and cold to grids of 6SN7, and 100k from each grid to ground.
In a balanced preamp design by Morgan Jones which uses 6SN7 and variable shunt between signals, the impedance is kept high to avoid loading the tube phono stage ahead of it, and the low hf cutoff is dealt with by positive capacitance feedback. In Allen Wright's balanced preamp the shunt arrangement was discarded because it presented a variable load which altered the RIAA of the phono stage. Apparently, using Jason's version of Lightspeed, the series resistance changes along with the shunt, keeping impedance in a narrower range.
I'm able to drive my amps directly from the CD player which has a volume control. I can drive my amps directly also from the phono stage, which is all FET, but has no volume control. Right now I use MM gain for MC cartridge to get generally usable fixed volume. I want to go back to MC gain and throttle the output with the Lightspeed. Maybe with this phono stage load on output doesn't affect RIAA.
I don't know enough to figure out a useful configuration. Some guidance would be welcomed.
Thanks --Terry C.
Greetings, and thanks to georgehifi for making Lightspeed available. I hope to build the attenuator for balanced line use and noted that Jason in post #1514, instead of using eight LDRs altogether, used only six --three per channel. Two are in series with the signal leads for each channel and one shunts between the leads.
I'd like to find out whether I can use Jason's balanced Lightspeed arrangement without altering my amplifiers. The amps are Atma-Sphere M60s with 4k7 resistors from each input hot and cold to grids of 6SN7, and 100k from each grid to ground.
In a balanced preamp design by Morgan Jones which uses 6SN7 and variable shunt between signals, the impedance is kept high to avoid loading the tube phono stage ahead of it, and the low hf cutoff is dealt with by positive capacitance feedback. In Allen Wright's balanced preamp the shunt arrangement was discarded because it presented a variable load which altered the RIAA of the phono stage. Apparently, using Jason's version of Lightspeed, the series resistance changes along with the shunt, keeping impedance in a narrower range.
I'm able to drive my amps directly from the CD player which has a volume control. I can drive my amps directly also from the phono stage, which is all FET, but has no volume control. Right now I use MM gain for MC cartridge to get generally usable fixed volume. I want to go back to MC gain and throttle the output with the Lightspeed. Maybe with this phono stage load on output doesn't affect RIAA.
I don't know enough to figure out a useful configuration. Some guidance would be welcomed.
Thanks --Terry C.
Terry if you use a series/shunt LDR arrangement Lightspeed as I've designed, your all FET phono stage should have a low enough output impedance to drive to the Lightspeed and the Atma-Sphere M60s.
It would be nice to see a circuit of that phono stage.
I have a friend that uses a tube phono stage that has the tube SLCF output (attached) which was a buffer originally inside an old Tektronics scope, which is around 200ohm output and it drives the production Lightspeed Attenuator with a pair of single ended 13E1's monoblocks (28watts each) into Wilson Watt Puppy 7's and it sounds magnificent.
Cheers George
It would be nice to see a circuit of that phono stage.
I have a friend that uses a tube phono stage that has the tube SLCF output (attached) which was a buffer originally inside an old Tektronics scope, which is around 200ohm output and it drives the production Lightspeed Attenuator with a pair of single ended 13E1's monoblocks (28watts each) into Wilson Watt Puppy 7's and it sounds magnificent.
Cheers George
Attachments
Lightspeed remote control
Hi Udaily,
The DS1802 is a bit tricky to use directly as a volume control as there are strict voltage limits for signal levels. The audio performance is not at the level I require in my system. However it has proved to be very useful as the control interface in the VCCS remote control.
Hi Jh,
Already done.
There is space for the LDRs at one end or you can fit screw terminal connectors and hard wire the LDRs at the input/output sockets.
There is also space on the board for a 12 volt version of the ultra low noise wide bandwidth regulator that I have recently production engineered for the Buffalo Sabre DAC power supply.
I have also designed an infra-red receiver board based on the Holtek HD12D and will be designing the matching Transmitter board with the Holtek HD12A and rechargeable battery power shortly. OK, I said I would not be doing the infra-red part of the project but I decided I would like things tidy in my system. The girls complain otherwise. So there will be a full set of boards available for those who would prefer this.
Hi Rolls,
The VCCS board will not drive a motorised pot. I used to use a slightly different remote control system using the Holtek chips with a motor driver for this function. Maybe I mentioned this in the thread in the past or you could be confusing the VCCS design with someone else’s motorised pot design posted earlier in the thread.
One thing I have learned over the years is that no matter how you present a design someone will want to do it differently. Whilst I respect your wishes for a rotary control, to be frank I am pleased to get rid of rotary controls in my system even for use in the function of varying the current to the LDRs. Their matching (if using dual pots) and long term reliability are questionable.
Hi SamL,
Good point. Without power both the LDRs will be at maximum resistance allowing signal through to the power amp from any energised sources connected to the Lightspeed. The signal level will be dependant on the resistance ratio of the series LDR, and the resultant of the shunt LDR in parallel with the power amplifier input impedance. I did mention this earlier in the thread suggesting an automatic mute circuit as a solution. I have designed a few of these in the past for consultancy projects. When I get a moment I will root through my old consultancy files for any that are not licensed to clients that may be of use.
I switch the whole system on and off at the same time via a master switch. There is no switch on/off thump or signal bleed through in my system during these actions. My line source arrays are 105 dB for 1watt sensitive so I would be aware of any problems using this on/off technique.
Regards
Paul
Hi Udaily,
The DS1802 is a bit tricky to use directly as a volume control as there are strict voltage limits for signal levels. The audio performance is not at the level I require in my system. However it has proved to be very useful as the control interface in the VCCS remote control.
Hi Jh,
Already done.
There is space for the LDRs at one end or you can fit screw terminal connectors and hard wire the LDRs at the input/output sockets.
There is also space on the board for a 12 volt version of the ultra low noise wide bandwidth regulator that I have recently production engineered for the Buffalo Sabre DAC power supply.
I have also designed an infra-red receiver board based on the Holtek HD12D and will be designing the matching Transmitter board with the Holtek HD12A and rechargeable battery power shortly. OK, I said I would not be doing the infra-red part of the project but I decided I would like things tidy in my system. The girls complain otherwise. So there will be a full set of boards available for those who would prefer this.
Hi Rolls,
The VCCS board will not drive a motorised pot. I used to use a slightly different remote control system using the Holtek chips with a motor driver for this function. Maybe I mentioned this in the thread in the past or you could be confusing the VCCS design with someone else’s motorised pot design posted earlier in the thread.
One thing I have learned over the years is that no matter how you present a design someone will want to do it differently. Whilst I respect your wishes for a rotary control, to be frank I am pleased to get rid of rotary controls in my system even for use in the function of varying the current to the LDRs. Their matching (if using dual pots) and long term reliability are questionable.
Hi SamL,
Good point. Without power both the LDRs will be at maximum resistance allowing signal through to the power amp from any energised sources connected to the Lightspeed. The signal level will be dependant on the resistance ratio of the series LDR, and the resultant of the shunt LDR in parallel with the power amplifier input impedance. I did mention this earlier in the thread suggesting an automatic mute circuit as a solution. I have designed a few of these in the past for consultancy projects. When I get a moment I will root through my old consultancy files for any that are not licensed to clients that may be of use.
I switch the whole system on and off at the same time via a master switch. There is no switch on/off thump or signal bleed through in my system during these actions. My line source arrays are 105 dB for 1watt sensitive so I would be aware of any problems using this on/off technique.
Regards
Paul
balanced Lightspeed
Thanks for your responses, Zen Mod and George. I'm too new here so I can't e-mail Jason to find out what he did. I decided to experiment first using normal potentiometers to find out what works, then make a Lightspeed. The idea of using a variable shunt across hot and cold signals of the balanced input is attractive because it means fewer parts to match. Using your design seemed likely to be fine, George, but you warned repeatedly about the extra work. I don't mind really as long as it will sound good.
Phono stage is Coda 03p. I use it balanced in-balanced out, but the user's book suggests that the RIAA circuit itself is single-ended and that's what it looks like on the circuit board. Kinda hard to tell, lots of little parts. Output impedance balanced is 150 ohms. I could post a picture, too, if I weren't new here. Anyway, the MC gain setting is way too loud, so I'm using MM setting. I followed Arthur Salvatore's advice on High End Audio site that best line stage is no line stage. Got rid of mine in exchange for a better tone arm. But some LPs aren't loud enough.
Before I discovered the Lightspeed, I was ready to build a minimal sort of linestage by Richard Sears, Triode Guy on the internet, which uses 6SN7s feeding output transformers. The input has variable shunt across the signals to control volume. Don't have anything against the transformers except they're not cheap.
Thanks.
-Terry C.
Thanks for your responses, Zen Mod and George. I'm too new here so I can't e-mail Jason to find out what he did. I decided to experiment first using normal potentiometers to find out what works, then make a Lightspeed. The idea of using a variable shunt across hot and cold signals of the balanced input is attractive because it means fewer parts to match. Using your design seemed likely to be fine, George, but you warned repeatedly about the extra work. I don't mind really as long as it will sound good.
Phono stage is Coda 03p. I use it balanced in-balanced out, but the user's book suggests that the RIAA circuit itself is single-ended and that's what it looks like on the circuit board. Kinda hard to tell, lots of little parts. Output impedance balanced is 150 ohms. I could post a picture, too, if I weren't new here. Anyway, the MC gain setting is way too loud, so I'm using MM setting. I followed Arthur Salvatore's advice on High End Audio site that best line stage is no line stage. Got rid of mine in exchange for a better tone arm. But some LPs aren't loud enough.
Before I discovered the Lightspeed, I was ready to build a minimal sort of linestage by Richard Sears, Triode Guy on the internet, which uses 6SN7s feeding output transformers. The input has variable shunt across the signals to control volume. Don't have anything against the transformers except they're not cheap.
Thanks.
-Terry C.
Lightspeed remote control
Hi Marc,
There is an assessment of numbers for a group buy of the remote controlled voltage controlled current source (VCCS) printed circuit boards/modules in progress. Estimated cost for the circuit board with the application note is around £12, for the built and tested module with application note approx £60. Infra red transmitter and receiver boards will also be available although I have not finished the transmitter layout and therefore cannot cost this yet.
Regards
Paul
Hi Marc,
There is an assessment of numbers for a group buy of the remote controlled voltage controlled current source (VCCS) printed circuit boards/modules in progress. Estimated cost for the circuit board with the application note is around £12, for the built and tested module with application note approx £60. Infra red transmitter and receiver boards will also be available although I have not finished the transmitter layout and therefore cannot cost this yet.
Regards
Paul