AudioCircle
Other Stuff => Archived Manufacturer Circles => Paul Hynes, Paul Hynes Design => Topic started by: Paul Hynes on 14 Nov 2010, 01:02 pm
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Infra Red Remote Control LDR Volume Control.
I have been using LDR volume control for many years in the form of an L-pad with a series resistor and a shunt LDR without knowing anything of George Stantscheff’s Lightspeed volume control. This was the same configuration George used in his early products. George had a further idea of making the series element of the L-pad an LDR too and this improved the performance even further. A couple of years ago I came across a thread on DIY Audio that was devoted to George’s Lightspeed design and decided to try his latest configuration in my system. It was an immediate upgrade on the previous series resistor/shunt LDR design. As far as I am concerned it is without doubt the best method of volume control I have ever used with respect to sound quality.
Please note that Lightspeed is the name George has been using for his production volume controls and this should not be used for any of the LDR volume control clones that are now available. For those interested in George’s product he can be contacted at georgehifi@optusnet.com.au
The Lightspeed volume control uses a standard dual potentiometer to adjust the current in the LDR LEDs thus varying the signal attenuation by controlling the LDR resistance. There is no remote control option on the Lightspeed. I am used to the convenience of remote control so decided to design one for myself using voltage controlled current sources interfaced with infra-red control modules. I mentioned this on Georges Lightspeed thread on DIY Audio and a lot of interest was shown. I decided that it would be a good DIY project to add to the thread and with George’s blessing offered a group buy to those who had shown interest. The circuit was published around a year and a half ago and a printed circuit board run was commissioned. I offered a set of boards for those with suitable DIY skills and also built and tested modules for those with less experience with a soldering iron. The boards and modules were priced to cover the provision costs with no additional business profit added.
The VCCS LDR current source drivers can be configured for single ended or balanced signal processing and provide Volume up/down and Channel Balance left/right. The VCCS can be controlled with four momentary switches fitted to your preamp front panel and/or used with the Infra Red Transmitter and Receiver modules to give the remote control function. The LDRs are not provided with the module. They should be purchased in matched sets from Uriah Daily at http://www.buildanamp.com/
Some technical information and photos :-
VCCS circuit
http://i700.photobucket.com/albums/ww7/paulhynes/VCCS1C.jpg
IRT circuit
http://i700.photobucket.com/albums/ww7/paulhynes/IRT1A.jpg
IRR circuit
http://i700.photobucket.com/albums/ww7/paulhynes/IRR1A.jpg
VCCS photo
http://i700.photobucket.com/albums/ww7/paulhynes/VCCS1A1.jpg
All modules photo
http://i700.photobucket.com/albums/ww7/paulhynes/LightspeedRemoteControl.jpg
VCCS with ultra low noise regulators
http://i700.photobucket.com/albums/ww7/paulhynes/Picture2019.jpg
LDR remote control review
http://www.tnt-audio.com/accessories/ph_ldr_volume_control_e.html
There is still plenty of interest for the VCCS control system and because of this the boards and modules are still available for anyone wanting to set up a DIY infra-red remote controlled LDR volume control.
The prices are still the same as when they were introduced and are :-
VCCS (voltage controlled current source LED control)
PCB £12
Built module £60
IRT (transmitter module) and IRR (receiver module) sold as a matching pair
PCB £13.77
Built modules £49.60
Low noise regulators for the VCCS (2 x shunt and 1 series)
Built and tested modules only - £96 for the three.
Insured air carriage and packing will be charged at cost and is subject to destination. This can be quoted at the time of enquiry.
If you have any questions about application of the modules post them on this thread for discussion and this will also act as a knowledge source for others considering LDR volume control.
Regards
Paul
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Paul,
Can you please explain how this setup would be configured for a balanced option?
Thanks!
Tom
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Paul,
Can you please explain how this setup would be configured for a balanced option?
Thanks!
Tom
+1
And, could you please give us a price for a fully tested, fully built modules for balanced purposes including remote? Please also include the price for the ultra-low noise regulators a well.
And any specifications to ensure compatibility?
Thanks!
Anand.
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Hello Tom,
I will try to find some time over the next few days to draw the configuration for series balanced operation and for shunt balanced operation. I will post as soon as it is done.
Hello Anand,
I have added the cost of the low noise regulators to the first post. The VCCS set up for balanced operation costs the same as the single ended version.
The number of LDRs and the way they are wired dictates how they operate. This will be clear once I post the drawings for balanced operation. The 12 volt series regulator on the VCCS board is changed for an 18 volt regulator and the shunt regulator at the bottom of the reference chain is set up to operate at a higher voltage level to allow series connection of LDR LEDs.
The overall impedance of the volume control depends on the current source range setting resistor values. These resistor values can be changed to suit your system requirements.
Regards
Paul
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I'm using George's LSA now and I love it. However, I have balanced outs on my DAC (PS Audio Perfectwave) and balanced ins on my monoblocks (NAT Audio Generators). I'd be very interested in a fully built/tested balanced LDR with remote.
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Sorry about the delay Tom, here is a re-draw of the circuitry to allow balanced operation :-
http://i700.photobucket.com/albums/ww7/paulhynes/VCCS4.jpg
Catastrofe, are you looking for built and tested modules so you can finish the build yourself?
Regards
Paul
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Sorry about the delay Tom, here is a re-draw of the circuitry to allow balanced operation :-
http://i700.photobucket.com/albums/ww7/paulhynes/VCCS4.jpg
Catastrofe, are you looking for built and tested modules so you can finish the build yourself?
Regards
Paul
Paul,
Thank you. It is very clear now. Since you now have 2 LDR's in series, which devices need to be matched for balanced configuration? I just want to make sure that it is achievable given Uriah's matching method, lot sizes, etc. I could probably send a note direct to him if you'd prefer.
Tom
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Hi Tom,
Ideally all the series LDRs should be matched together and all the shunts matched together. However, Uriah has found it hard to get four LDRs matched so if you get matched pairs you can use a matched pair for phase and anti-phase signals in each of the left and right channels series LDRs and the same with the shunt LDRs. In other words a matched pair for the two LDR LEDs in each op-amp control loop.
Any channel imbalance can be adjusted with the balance control on the VCCS module.
Regards
Paul
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Hi Tom,
Ideally all the series LDRs should be matched together and all the shunts matched together. However, Uriah has found it hard to get four LDRs matched so if you get matched pairs
you can use a matched pair for phase and anti-phase signals in each of the left and right channels series LDRs and the same with the shunt LDRs. In other words a matched pair for the two LDR LEDs in each op-amp control loop.
Any channel imbalance can be adjusted with the balance control on the VCCS module.
Regards
Paul
Thanks Paul! I've been chatting with Uriah and he indicated that while you could TRY it, he only guarantees matching at 4 points in the LDR's, which isn't enough for balanced use. Based on that he doesn't recommend the balanced option for now but I may still try the single ended just to get a feel for it.
Tom
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Hi Tom,
I can see what Uriah is saying. Because of the limited matching points there may be errors in phase balance at certain settings. I do not see this as a major issue as the effects will be relatively benign sonically in a domestic system. The benefits of using LDRs as the volume control element should far outweigh the lack of absolute phase balance. Absolute phase balance through the audio band and at all operating levels is rare in balanced equipment. This does not stop people using balanced equipment. Channel balance can be adjusted via the balance control if you build a VCCS module modified for balanced LED control.
I’m sure a couple of guys have set up balanced LDRs successfully. Try asking on the Lightspeed thread on DIY Audio. If they have had problems with set up I’m sure they will be willing to share their experience.
Does anyone on this forum who has set up a balanced LDR volume control care to share their experience?
Regards
Paul
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Does anyone on this forum who has set up a balanced LDR volume control care to share their experience?
Hi everybody,
I have assembled a balanced LDR volume control using series connected LDR's and Paul's VCCS modules set up specifically for this purpose and with upgraded power supplies. I have tested the volume control with LDR's paired by myself and it sounds perfectly great. I would not know how phase unbalance sounds but if this is what I'm hearing then it is truly a very pleasant sound!
I have not boxed the project up yet as I'm not satisfied with the "bird-nest" of LDRs that I created for testing. There is not room for the LDRs on the VCCS module so I would like to place them neatly on a pair of small PCBs (one per channel) together with the XLR connectors. I have no experience in PCB layout so I'm still hoping somebody could help me on this embarrassing and trivial problem.
Cheers,
Nic
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There is not room for the LDRs on the VCCS module so I would like to place them neatly on a pair of small PCBs (one per channel) together with the XLR connector
Why don't you put the LDR;s directly on the input and output connectors. You would have to place the connectors strategically close. This would reduce introduced wire length and other noise.
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I just now read this thread and want to pipe in with my experience with LDR volume controls. I have owned several types of volume controls---Placette volume control (Vishay resistors + contacts), various transformer volume controls (including Serge Schmidlin's Silver Rock), etc. None of these came even close to George's Lightspeed. Direct comparisons, for instance, with a Placette and the Silver Rock---no slouches in passive pre's---were obvious: the Lightspeed trumped. And by a wide margin. It took me the whole of probably 30 seconds to judge the Lightspeed's superiority in these comparison.
One issue I piped in on in the DIY Lightspeed thread was the stability of the voltage supply feeding the Lightspeed. A varying voltage across the powered component of the LDR theoretically should modulate, though with the LDR's characteristic response-delay, the music signal passing through the resistive component. I experimented with this and found, to my observation, that a rock-solid supply indeed made a small sonic difference. I was then unaware of Paul's excellent supplies and used an Audiocom Invisus regulator to feed the LDR unit. I would think a Lightspeed modified with a Hynes series reg would be ideal. My 2¢.
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Are the remote control PCBs still available, Paul? Thanks.
Rich
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Hi Rich,
I have 60 sets of remote control boards left. Prices are still the same but shipping cost may be slightly different from the original list. If you let me know what you want I can work out the shipping cost for you.
Regards
Paul
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Hi Paul
A bit of a simple question, really.
Aside from your boards and the LDRs, I understand I'll need a PSU. What would I actually need to buy? Do you offer a finished PSU that I could purchase?
TIA
Dave
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Are these the same remote controls Uriah sells with his Lighter Note volume control?
Best,
Ed
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As far as I am aware they are not the same as I have no agreement in place with Uriah.
Regards
Paul
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Any word on a fully assembled, finished product, cost, pics, or will this only be DIY?
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I have an agreement with George Stantscheff not to sell finished products that have a volume control using his Lightspeed configuration. George was happy to allow the use of the remote control modules for DIY projects or the PCBs for total self build.
Regards
Paul
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Hello Paul,
What is the current situation with ldr/remote boards?
I would like to purchase a set of completed/tested boards together with anything else you can supply to minimise the completion time. A full kit would be ideal, but I understand your agreement with George.
Thank you,
Dan.
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Hi Paul,
I was also wondering if you still have completed boards available for your LDR volume control.
Thank you,
Mas
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Hello Dan and Mas,
I still have boards for the project and can provide the modules. Prices are still the same although shipping costs have increased a little since I posted the prices. Current lead time is around 25 to 30 working days for the modules. Let me know what you want and the destination and I will give you the modules cost plus the shipping cost.
Regards
Paul
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Hello Paul,
I would like to get all three boards, built and tested, with the low noise regulators. Is it possible to fit the remote control to replace the volume and balance pots on an existing LDR volume control? I am in Los Angeles CA USA>
Thank you,
Mas
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Hello Mas,
The VCCS was designed to control George’s Lightspeed configuration of LDR’s although it can be set up to control other configurations as well. Control functions are L&R volume up, L&R volume down and L trim, R trim for balance control. These are push button controls and they can also be replicated on the preamp chassis working in parallel with the remote control receiver module if required. Let me know how your LDR’s are configured and I will assess compatibility.
The cost of the built and tested modules :-
VCCS voltage controlled current source module £60
IRTR transmitter and receiver modules £49.60
3 off low noise regulator modules £96
Insured carriage and packing to Los Angeles £14.40
Total £220
Paypal payment add 3.4% and bank transfer payment add £6 bank processing fee.
Lead time is approx 25 to 30 working days for these modules.
Regards
Paul
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Hi Paul,
I have Uriah's Lighter Note attenuator, but I would like your's as well to see which sounds better. Is it possible to use your remote for both?
Thanks,
Mas
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Hey Paul,
Interested in a setup, have Uriahs boards sans powersupply section so have matched LDR'S, am in Australia, what are your thoughts re requirements please?
Thanks,
Drew.
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Mas,
I am not familiar with Uriah’s control circuitry for the lighter note so cannot say whether the remote control modules will interface with it. The remote control transmitter and receiver modules were specifically designed to drive the VCCS (Voltage Controlled Current Source) module, which drives the LDR LEDs directly.
Drew,
The VCCS module has provision for fitting the LDRs on board. It doesn’t need Uriah’s boards to operate as a volume/balance control.
Regards
Paul
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Hi Paul,
What is the range of the current output from your vccs?
Thanks.
Ng
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Hi Chai Soon,
The VCCS current output can be set to suit the required range of operation of the LDR, by changing the current setting resistors. The maximum available current is 20ma per current source.
Regards
Paul
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Hey Paul,
Appreciate the reply, can you advise if this will go to silent? Does it have mute functionality?
Just trying to get my head around it.
Thanks,
Drew.
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PM sent.
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Hi Drew,
In my system the volume control reduces to silence, but in other systems it will depend on the loudspeaker sensitivity and amplifier voltage gain whether the minimum setting is audible. High sensitivity loudspeakers and high gain amplifier would be the worst case scenario for any audible residual signal at minimum volume.
There is no mute function active on the VCCS module as the remote control chip only has 4 channels.
Regards
Paul
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What would be the prices for the 3 PCB's plus all the required components? I understand that the LDR's have to be gotten from buildanamp.
I reside in Singapore.
Thanks.
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Hello escutcheon,
3 PCB’s and all components will cost £83. Insured carriage and packing to Singapore will cost £14.
Regards
Paul
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Hello,
I am the proud owner of a virtue sensation m901. It has a motorized 20k pot. Just wondering if it would be possible and have benefits to replace it with the LDR volume control.
Sincere greetings, Edward