Re: Re: Re: Re: another Lightspeed
Thanks for the checklist, seems useful.
1. Yeah. How would you match the LDR with my 10k ohm F3? Buffer or super-duper source?
6: in english? If you mean to put the volume control in the dac, what's the point of the Lightspeed?
7: see point 1
Tolu said:As we say in Germany: Don't shoot with canons at sparrows.or for the english ones: don't break a butterfly on a wheel
If you use a well built PS with not too much ripple, the effect of additional caps isn't audible. Don't expect wonders by using caps! The discussion about the brand hasn't any influence, too. Remember, the caps aren't in the signal path and the LEDs are fed with DC (more or less!
I am not so experienced with LS as George but I did some experiences, too.
1. The main thing is device matching, device matching, device m...!
2. Keep output impedance low!
3. A well built PS with 7805 is sufficient (for my wooden ears).
4. Use thermal coupling of the optocouplers.
5. Omit relais for channel switching.
6. If you want remote control and perfect channel matching with defined steps -> use DACs
7. Avoid buffers until they aren't absolutely necessary
Enjoy airlight listening!
Thanks for the checklist, seems useful.
1. Yeah. How would you match the LDR with my 10k ohm F3? Buffer or super-duper source?
6: in english? If you mean to put the volume control in the dac, what's the point of the Lightspeed?
7: see point 1
georgehifi said:
Hello George, I sent you an email through this site: did you get it?
If so, can we discuss the matter through.
The alternative to the LDR I'm considering is the Bent AVC, which has no impedance issues. I have to carefully evaluate the sound quality. With the buffer also the placette would become a viable solution.
I have some questions about volume steps and remote (which i need).
I'm still catching up with the thread...
If you want the most transparent, go the Lightspeed forget the rest they are all coloured in some way. It's the closest to pluging the source (CD) directly into the power amp, we have now proved this may times against all other pre's passive or active.
As for steped volume control there is no problem in using a 24 or 32 position resistor switched pot for the control for the leds in the Lightspeed Attenuator so long as it mimics a 100k log pot.
As you said even using Tentlabs digital readout volume control as the led controler in the Lightspeed, but ouch that's getting expensive $400aud just to give a digital readout for the Lightspeed.
Cheers George
As for steped volume control there is no problem in using a 24 or 32 position resistor switched pot for the control for the leds in the Lightspeed Attenuator so long as it mimics a 100k log pot.
As you said even using Tentlabs digital readout volume control as the led controler in the Lightspeed, but ouch that's getting expensive $400aud just to give a digital readout for the Lightspeed.
Cheers George
georgehifi said:
Good, that's what wanted to hear.
Now i have to decide if i want a preamp box or put it into the dac.
You've got mail
Probably Guido Tent would deduct the unused parts from his volume controller and significantly reduce the price, likely to ~150eur or allow a trade-in for some components i own that i havent used
So Tent would be my first choice.I need at least 60 steps, better 0.5dB each, but then finding a display with decimals would be an issue. Would i need to buy other parts to make it match the tent with the lightspeed?
Heck i could even buy an used placette which should go for us$6-700 just to have that many steps.
Eventually, could you sell me an unboxed unit? the VFD wouldnt fit in your case anyway, similar for some regulated power source.
Yes, a very elaborate one, didn't take too long for them to clone it and glitz it up.
Shame about the relays though, defeats the whole purpose of the Lightspeeds advantages.
If you navigate through the maze of that website you eventually find what they sell the kits for in Japan. A single-ended kit(unbalanced) 104,500yen the balanced kit is 164,500yen.
Hope they use the NSL32SR2S in series/shunt and hand matched, otherwise it's not going to be worth it.
Anyone got one yet as they've been out now for nearly a year now??
Cheers George
Shame about the relays though, defeats the whole purpose of the Lightspeeds advantages.
If you navigate through the maze of that website you eventually find what they sell the kits for in Japan. A single-ended kit(unbalanced) 104,500yen the balanced kit is 164,500yen.
Hope they use the NSL32SR2S in series/shunt and hand matched, otherwise it's not going to be worth it.
Anyone got one yet as they've been out now for nearly a year now??
Cheers George
George could you have a look here
http://www.diyaudio.com/forums/showthread.php?s=&postid=1697215#post1697215
and answer if all LDRs are matched?
Thanks.
http://www.diyaudio.com/forums/showthread.php?s=&postid=1697215#post1697215
and answer if all LDRs are matched?
Thanks.
Telstar said:
High Telstar,
I used one of Mikkels remotes with a motorized pot. Wich one it was you can read in one of my posts I think about half a year ago.
Easy to build and works flawlessly! I recommended Mikkel to the forum.
If you can't find what I did exactly, I can look it up for you,just let me know,
Cheers,
Ed Linssen
LDR remote control
George I am embarassed. It has been a long time. Sorry but I have been busy.
Over the Christmas break I finally managed to get the time to populate a set of remote control boards and debug them. The system works very well allowing volume up both channels, volume down both channels, left balance and right balance. The available working range is more than adequate in my system. Matching is noticably less critical, in practice, with the balance control facility although a completely unmatched set of LDRs did show some small discrepancies on the scope due the the 1 dB step function of the Dallas DS1802 not quite countering any mismatches with the LDRs. I did not notice any problems with this in my system. Nelson Pass provided much information about the useful LDR operating range with particular reference to the Lightspeed configuration and I adapted the design to follow his recommendations. Thank you Nelson. Re-working for lower led current range allows a simplification of the led drive circuit as the opamps in the voltage controlled current source can easily deliver the required current range without thermal stress. The system circuit is simple and inexpensive to implement.
The boards can (I hope) be seen at the following address :-
http://i700.photobucket.com/albums/ww7/paulhynes/LSremote1.jpg
I am driving the volume control directly from an Altmann Attraction DAC and the volume control feeds one DC coupled power mosfet in source follower mode driving my open baffle line source array loudspeakers. The line array has all drivers in parallel to give a 0.75 ohm load and because of this and the efficiency of 105 dB for 1 watt/1mtr I need very little voltage swing to generate considerable sound pressure levels. In fact there is no voltage gain stage after the Altmann which has a healthy output at low impedance. The transparency to the musical performance is very impressive. I certainly prefer the Lightspeed configuration to the fixed series resistor/shunt LDR configuration or any other volume control method I have tried.
George, if you are up for trying the remote control I will prepare a set of boards for you, gratis of course.
Regards
Paul
George I am embarassed. It has been a long time. Sorry but I have been busy.
Over the Christmas break I finally managed to get the time to populate a set of remote control boards and debug them. The system works very well allowing volume up both channels, volume down both channels, left balance and right balance. The available working range is more than adequate in my system. Matching is noticably less critical, in practice, with the balance control facility although a completely unmatched set of LDRs did show some small discrepancies on the scope due the the 1 dB step function of the Dallas DS1802 not quite countering any mismatches with the LDRs. I did not notice any problems with this in my system. Nelson Pass provided much information about the useful LDR operating range with particular reference to the Lightspeed configuration and I adapted the design to follow his recommendations. Thank you Nelson. Re-working for lower led current range allows a simplification of the led drive circuit as the opamps in the voltage controlled current source can easily deliver the required current range without thermal stress. The system circuit is simple and inexpensive to implement.
The boards can (I hope) be seen at the following address :-
http://i700.photobucket.com/albums/ww7/paulhynes/LSremote1.jpg
I am driving the volume control directly from an Altmann Attraction DAC and the volume control feeds one DC coupled power mosfet in source follower mode driving my open baffle line source array loudspeakers. The line array has all drivers in parallel to give a 0.75 ohm load and because of this and the efficiency of 105 dB for 1 watt/1mtr I need very little voltage swing to generate considerable sound pressure levels. In fact there is no voltage gain stage after the Altmann which has a healthy output at low impedance. The transparency to the musical performance is very impressive. I certainly prefer the Lightspeed configuration to the fixed series resistor/shunt LDR configuration or any other volume control method I have tried.
George, if you are up for trying the remote control I will prepare a set of boards for you, gratis of course.
Regards
Paul
Good to hear Paul, great all is working out well. I don't need the boards all the same thanks for your kind offer, as my control is within arms length of my listening position, keep them to sell, looks like you earned it.
All should vote here http://www.diyaudio.com/request/ for a Passive Attenuator forum.
Cheers George
All should vote here http://www.diyaudio.com/request/ for a Passive Attenuator forum.
Cheers George
If any of you guys need a phono pre with passive LDR or active (tube headphone) LDR volume control there is a Melos Gold for sale on Audiogon, sounds like the real deal fully working, remember this is early LDR not Silonex, and it is also from what I remember stage 1 Lightspeed technology.
The guy says it's working 100% he looks like a budding tech seeing the old test gear in the background.
The weak point of these units was the LDR relibility but he says this one is fine.
Knock yourselves out.
http://www.audiogon.com/cgi-bin/cls.pl?preatube&1234800862&/Melos-Sha-Gold-guarantee-to-wo
Cheers George
The guy says it's working 100% he looks like a budding tech seeing the old test gear in the background.
The weak point of these units was the LDR relibility but he says this one is fine.
Knock yourselves out.
http://www.audiogon.com/cgi-bin/cls.pl?preatube&1234800862&/Melos-Sha-Gold-guarantee-to-wo
Cheers George
Hey, a friend of mine had a Melos SHA that was three units. A power supply, pre and the phono. He brought it over one night after it stopped working. I opened it up and saw the tube filaments not firing. After finding goofy voltages on the heater pins, I changed out the rectifier and the pre worked perfectly. He left it with me a couple weeks to listen to it - all I remember was it did not have much gain for my rig, but sounded real nice.We never got the phono working...he was ecstatic I fixed the preamp section, because no one would touch it.
Anyway, I did not know this was a LDR base pre. So this and the Hafler Iris are LDR based? Are there any more commercial pres out there that have the LDR based volume control?
Anyway, I did not know this was a LDR base pre. So this and the Hafler Iris are LDR based? Are there any more commercial pres out there that have the LDR based volume control?