Thanks!!
I received my LDRs yesterday - a big thanks to Uriah for supplying them, and also answering my daft questions! 🙄
I couldn't help it - I had to lash it all together and see how these little things sounded. I used a 5V super-regulator I had, matched current-limiting resistors, some gash 1K trimpots and an RK-27 100K pot. That's it!
Bottom line = EXCELLENT!! It's made a huge improvement to my current system, and has underlined the need for me to get my amps sorted out!!!!
For those of you still pondering the Lightspeed, I urge you to try this brilliant idea.
And finally, a huge thanks to George for sharing this with us!! 😀 I'm a convert and can't wait to test this against the other passive preamps I have waiting in the wings.....
Cheers
Jon
I received my LDRs yesterday - a big thanks to Uriah for supplying them, and also answering my daft questions! 🙄
I couldn't help it - I had to lash it all together and see how these little things sounded. I used a 5V super-regulator I had, matched current-limiting resistors, some gash 1K trimpots and an RK-27 100K pot. That's it!
Bottom line = EXCELLENT!! It's made a huge improvement to my current system, and has underlined the need for me to get my amps sorted out!!!!
For those of you still pondering the Lightspeed, I urge you to try this brilliant idea.
And finally, a huge thanks to George for sharing this with us!! 😀 I'm a convert and can't wait to test this against the other passive preamps I have waiting in the wings.....
Cheers
Jon
jackpipe said:
The LDR's can develop a short term memory issue.
I had worked on a HV supply using an LDR and LR8N3 HV regulator (Supertex) -- problem with an LDR is that it isn't fast enough to respond to the error -- instead of nano-seconds it's milliseconds -- this isn't a problem when used as an attenuator.
One issue which Silonex raises -- but I haven't seen is the effect of parasitic capacitance in an LDR. My Perkin Elmer LDR's are flat out to 150kHz.
Jackinnj,
Have you tried the Silonex as an audio attenuator? I wonder about sound difference with Perkin Elmers. Silonex certainly isnt just like two regular resistors. If they were I would probably be using Dale films or something similar. The sound is just nutty how good it is so I wonder what the resistive material is and if the Elmers are the same.
Uriah
Have you tried the Silonex as an audio attenuator? I wonder about sound difference with Perkin Elmers. Silonex certainly isnt just like two regular resistors. If they were I would probably be using Dale films or something similar. The sound is just nutty how good it is so I wonder what the resistive material is and if the Elmers are the same.
Uriah
Lightspeed remote control
Hi Jackpipe,
The DS1802 is specified as having 1 dB steps of adjustment when used directly as the volume control. The contour of the LDRs has to be factored in to give the actual step increment. This will vary depending on what part of the LDR range you are operating in.
In practise, the balance function of the DS1802 worked well with a set of unmatched LDRs I used initially for test. I matched the LDRs in my system because I did not want to have to adjust balance every time I switched the system on. Like George, I do not have any drift problems. The balance control is still a useful option for dealing with imbalances in source, speaker and room response so I left it in.
Regards
Paul
Hi Jackpipe,
The DS1802 is specified as having 1 dB steps of adjustment when used directly as the volume control. The contour of the LDRs has to be factored in to give the actual step increment. This will vary depending on what part of the LDR range you are operating in.
In practise, the balance function of the DS1802 worked well with a set of unmatched LDRs I used initially for test. I matched the LDRs in my system because I did not want to have to adjust balance every time I switched the system on. Like George, I do not have any drift problems. The balance control is still a useful option for dealing with imbalances in source, speaker and room response so I left it in.
Regards
Paul
Lightspeed remote control
Hi Folks,
The IR boards have arrived this afternoon while I was out. It is too late for me to build and test a set today as I have family issues to deal with now. I will try and fit this in tomorrow. Once I have verified operation I can finish the application notes and get your orders prepared and shipped.
Regards
Paul
Hi Folks,
The IR boards have arrived this afternoon while I was out. It is too late for me to build and test a set today as I have family issues to deal with now. I will try and fit this in tomorrow. Once I have verified operation I can finish the application notes and get your orders prepared and shipped.
Regards
Paul
One thing that continually gets raised in criticism of this LDR approach is the high distortion of the LDRs. Here's a quote from Greg Ball (a former member here & developer of the SKA amp)
While these 3HD distortions emerge at high levels, they are insignificant at around 200mV🙂
What do people make of this in answer to the criticism, it sounds correct to me but I haven't seen this counter-argument before ?
While these 3HD distortions emerge at high levels, they are insignificant at around 200mV🙂
What do people make of this in answer to the criticism, it sounds correct to me but I haven't seen this counter-argument before ?
Attachments
jkeny said:
These are rms distortions which are still far lower than some tube amps and much lower than probably all speakers, music isn't rms.
Peak measured distortions (and they are low order) would be far lower than these figures, if it were a problem why does everyone love the sound so much?
Also the way Greg Ball uses them they are in "shunt" only arrangement with series resistor same as (my MkI) version, which is higher in distortion, maybe that's why he said what he said.
The series/shunt (my MkII) is not, this was why I recalled all my MKI version years ago and upgraded them to MkII. They sound far better than the MkI. And have a much lower attenuation level. And also have much better constant impedances.
The only down side, as now your all aware of, is the dreaded matching of the LDR's.
Cheers George
@ maximus
Hi Paul,
I thought about your doing, but I cannot understand your intention. The only sense (for me) for your (47k) DS1802 would be to adapt any kind of display. You don't need this... and I am not shure to adapt this in this kind of way.
I cannot see the advantage of your solution - compared to Georges MK II - thousand and ... posts before, i.e. using a motorized 100k Alps poti and any kind of remote controls for this and for switches (f.e. Alps remote set #13513 or this one by Thel - sorry german, but have a look at the pictures... ) 🙁
I see only the disadvantage of the missing trimmpotis (or whatever at this place...) for someone who does not miss them at first...
Perhaps you could clear up - also in the sense of updating this thread 🙂
Regards
Thomas
Hi Paul,
I thought about your doing, but I cannot understand your intention. The only sense (for me) for your (47k) DS1802 would be to adapt any kind of display. You don't need this... and I am not shure to adapt this in this kind of way.
I cannot see the advantage of your solution - compared to Georges MK II - thousand and ... posts before, i.e. using a motorized 100k Alps poti and any kind of remote controls for this and for switches (f.e. Alps remote set #13513 or this one by Thel - sorry german, but have a look at the pictures... ) 🙁
I see only the disadvantage of the missing trimmpotis (or whatever at this place...) for someone who does not miss them at first...
Perhaps you could clear up - also in the sense of updating this thread 🙂
Regards
Thomas
jkeny said:
The audio signal doesn't pass through the LDR's so how can they introduce distortion?
🙄
Marc the audio signal passes through the resistor element of the LDR which is varied by the light falling on it from the LED buried in the LDR. It's the resistive element distortion that the graph from Silonex shows.
George I agree with you, I was simply pointing out the counter argument to those that accuse LDRs of high distortion.
George I agree with you, I was simply pointing out the counter argument to those that accuse LDRs of high distortion.
Lightspeed remote control
Hi Thomas,
Please remember that I designed the VCCS plus IR system for myself, and it was purely to suit my own needs. All I need is an infra-red remotely controlled stereo volume control with balance control option and first class performance musically. That’s all. Nothing else. I do not try to complicate things when simple will do.
Interest developed on the thread has encouraged the progression to the preparation of the design for DIY enthusiasts. This project has to be dealt with in my spare time, which is limited. If people want to expand my design to suit their requirements I have no objections and within reason will be supportive of their efforts. This is a forum where new ideas can be discussed and developed. If you want to utilise a different design like the Thel 15 channel remote feel free to do so.
My design choices were based on the fact that I wanted to fit and forget the volume control. That is, it needed to be robust and not need servicing in the future. My experience of rotary potentiometers is that sooner or later they wear, become noisy and require replacement. A rotary motor driven potentiometer would still require an infra-red link with motor driver to suit my needs, so the control circuitry and printed circuit costs would still be there. The VCCS and IR remote solution is unlikely to be any more expensive than an Alps pot with IR control. The DS1802 has all the push button interface circuitry on chip, which makes this application easy.
The design does what it says on the packet. It is simple, uses readily available components, requires no programming experience and does not cost much money. The only advantage it has over George’s MKII is the remote control function, which is useful if you want remote control and are comfortable with some DIY activity. If not buy George’s Lightspeed, which is also good value for money. If you want a volume display, either design it yourself or look for another solution elswere.
Regards
Paul
Hi Thomas,
Please remember that I designed the VCCS plus IR system for myself, and it was purely to suit my own needs. All I need is an infra-red remotely controlled stereo volume control with balance control option and first class performance musically. That’s all. Nothing else. I do not try to complicate things when simple will do.
Interest developed on the thread has encouraged the progression to the preparation of the design for DIY enthusiasts. This project has to be dealt with in my spare time, which is limited. If people want to expand my design to suit their requirements I have no objections and within reason will be supportive of their efforts. This is a forum where new ideas can be discussed and developed. If you want to utilise a different design like the Thel 15 channel remote feel free to do so.
My design choices were based on the fact that I wanted to fit and forget the volume control. That is, it needed to be robust and not need servicing in the future. My experience of rotary potentiometers is that sooner or later they wear, become noisy and require replacement. A rotary motor driven potentiometer would still require an infra-red link with motor driver to suit my needs, so the control circuitry and printed circuit costs would still be there. The VCCS and IR remote solution is unlikely to be any more expensive than an Alps pot with IR control. The DS1802 has all the push button interface circuitry on chip, which makes this application easy.
The design does what it says on the packet. It is simple, uses readily available components, requires no programming experience and does not cost much money. The only advantage it has over George’s MKII is the remote control function, which is useful if you want remote control and are comfortable with some DIY activity. If not buy George’s Lightspeed, which is also good value for money. If you want a volume display, either design it yourself or look for another solution elswere.
Regards
Paul
Hi Paul,
thank you for your informations... You forgot to say anything about the tuning of the LDRs (pots)...
Thanks!
Regards
Thomas
thank you for your informations... You forgot to say anything about the tuning of the LDRs (pots)...
Thanks!
Regards
Thomas
Lightspeed remote control
Hi Thomas,
It is possible to trim the current in each VCCS by adjusting the resistors that set the current in the voltage controlled current sources (VCCS).
Regards
Paul
Hi Thomas,
It is possible to trim the current in each VCCS by adjusting the resistors that set the current in the voltage controlled current sources (VCCS).
Regards
Paul
Hi Paul,
even all 8 (in case of balanced) LDRs?
Is there a way for switching relays with your IR system?
A documentation (on your website) would be rather helpful to avoid repeated questions 😉
Regards
Thomas
even all 8 (in case of balanced) LDRs?
Is there a way for switching relays with your IR system?
A documentation (on your website) would be rather helpful to avoid repeated questions 😉
Regards
Thomas
Lightspeed remote control
Hi Thomas,
There are 4 current sources and these can be individually trimmed.
I could have added more functionallity to the IR system, like source select. This was not necessary in my system as it is easy enough to switch source when selecting which vinyl or CD to play and it would also have increase complexity and costs. I may consider this if enough interest is shown in the future.
An application note is in preparation during my limited free time and it will be uploaded to my website once I finish re-writing the site to include a number of new products. In the meantime the list of materials will shortly be posted on the forum thread and application notes will be sent out with all board/module orders.
Regards
Paul
Hi Thomas,
There are 4 current sources and these can be individually trimmed.
I could have added more functionallity to the IR system, like source select. This was not necessary in my system as it is easy enough to switch source when selecting which vinyl or CD to play and it would also have increase complexity and costs. I may consider this if enough interest is shown in the future.
An application note is in preparation during my limited free time and it will be uploaded to my website once I finish re-writing the site to include a number of new products. In the meantime the list of materials will shortly be posted on the forum thread and application notes will be sent out with all board/module orders.
Regards
Paul
Lightspeed remote control
Hi Thomas,
I did not design the VCCS for balanced operation although it is possible to adapt it to do this by wiring the left and right phase LDR LEDs in series on each current source and adjusting the voltage reference chain and voltage regulator voltages to suit.
This will require matched pairs of LDRs. Current source resistor trimming and the balance control function will deal with left/right balance.
Regards
Paul
Hi Thomas,
I did not design the VCCS for balanced operation although it is possible to adapt it to do this by wiring the left and right phase LDR LEDs in series on each current source and adjusting the voltage reference chain and voltage regulator voltages to suit.
This will require matched pairs of LDRs. Current source resistor trimming and the balance control function will deal with left/right balance.
Regards
Paul
I am very happy with my LS MKII. I will try the following things in the next weeks.
1. Rising the input impedance to 500k
2. Using a tube buffer after the LS.
3. Finishing my DAC LS with LDR input selection
1. Rising the input impedance to 500k
2. Using a tube buffer after the LS.
3. Finishing my DAC LS with LDR input selection
