ssmith said:
Set up a dc power supply where you can accurately select 5 x dc voltages from 1v to 5v to feed the LED section of each one.
Then measure and plot the LDR section resistances of each one on a graph at those 5 x voltages, and match up 4 with the same resistance graph curve
Cheers George
Attachments
I took a similar approach but used the pot to vary the voltage in. Basically put the pot in the circuit. Set it to 9am and measure and record them all. Then 12, 3 and max. In fact I cut a corner, and put a bunch in parallel, set to 9am and measured them all after they stabilized for a minute. You can use IC sockets as a jig. There were very clear pairs that emerged. One matched pair on the series and another pair on the shunt and you are in business. Some have critsized this method, but my lightspeed clone tracks perfectly and sounds great. Out of 10 I got 4 good pairs.
powersupply
Hi Tubo.
You just need a fixed 5Volt DC-supply. The best way to do it is using an ordinary 12Volt DC wallwart. Than brin this voltage down in one or preferably two steps to 5VoltDC.
For my lightspeedclone this simple regulator, which is used by Doede Douma (www.dddac.de) is his 1543II Dac project, does his job really well.
Hi Tubo.
You just need a fixed 5Volt DC-supply. The best way to do it is using an ordinary 12Volt DC wallwart. Than brin this voltage down in one or preferably two steps to 5VoltDC.
For my lightspeedclone this simple regulator, which is used by Doede Douma (www.dddac.de) is his 1543II Dac project, does his job really well.
Attachments
George,
I read that lightspeed want to feed amps with high impedance. Is high impedance required in the AC realm or DC realm, or both?
The reason that I am asking is that I am designing a tube amp and is interested in using grid choke instead of grid resistor for the first stage.
"
A grid choke in the dc realm looks like a short in theory. But in the case of the BCP16NAGH it is more like about 5000 ohms. In the AC realm because of the inductance it looks an infinite resistence in theory or reality a Z of about 200K.
This is exactly what a tube wants to see. In the dc realm a very low impedance. In the AC realm you want the driving signal to see an infinate impedance and this is why a GC works so well. "
http://db.audioasylum.com/cgi/m.mpl?forum=magnequest&n=6465&highlight=grid+choke+input+impedance
I read that lightspeed want to feed amps with high impedance. Is high impedance required in the AC realm or DC realm, or both?
The reason that I am asking is that I am designing a tube amp and is interested in using grid choke instead of grid resistor for the first stage.
"
A grid choke in the dc realm looks like a short in theory. But in the case of the BCP16NAGH it is more like about 5000 ohms. In the AC realm because of the inductance it looks an infinite resistence in theory or reality a Z of about 200K.
This is exactly what a tube wants to see. In the dc realm a very low impedance. In the AC realm you want the driving signal to see an infinate impedance and this is why a GC works so well. "
http://db.audioasylum.com/cgi/m.mpl?forum=magnequest&n=6465&highlight=grid+choke+input+impedance
agent.5 said:
It likes to see high AC input impedance (>60k), low DC impedance won't worry the Lightspeed at all, it could be the perfect load for it.
But it may worry the source (CD Player) depending what output stage is used (eg. dc coupled), so tread carefully there, then again you'll have the series resistance of the Lightspeed itself unloading it again depending on where the volume is at.
Cheers George
remote control LS clone
Hi ed linssen
"Btw the remotecontrolething I did I can advice to anyone. It's the Remote1 with the 16-Alps motorpot. From: Dantimax."
Can you post a picture of this and indicate which modules of the kit you bought from Dantimax.
I am confused by the Dantimax website
I have also built the Lightspeed clone and is truly impressed. It bring the musician into the room !
I think we should nominate georgehifi as diy hi fi personality of the year if there is such a thing.
Thanks in advance.
kp93300
Hi ed linssen
"Btw the remotecontrolething I did I can advice to anyone. It's the Remote1 with the 16-Alps motorpot. From: Dantimax."
Can you post a picture of this and indicate which modules of the kit you bought from Dantimax.
I am confused by the Dantimax website
I have also built the Lightspeed clone and is truly impressed. It bring the musician into the room !
I think we should nominate georgehifi as diy hi fi personality of the year if there is such a thing.
Thanks in advance.
kp93300
answer to KP93300
Hi 93300,
Things I got from Mikkel,: " info@dantimax.dk" are:
Rem1 kit
Alps RK16 log motorpot 100K
And if you don't have it he sells cheap 12V dc wallwarts for powering the remote.
The codes he uses are the one's used by Philips on all his stuff.
RC5 code.
The hand-controlepart you can buy from him too for I think 5euros.
Succes and keep your ears up and open.
Ed
Hi 93300,
Things I got from Mikkel,: " info@dantimax.dk" are:
Rem1 kit
Alps RK16 log motorpot 100K
And if you don't have it he sells cheap 12V dc wallwarts for powering the remote.
The codes he uses are the one's used by Philips on all his stuff.
RC5 code.
The hand-controlepart you can buy from him too for I think 5euros.
Succes and keep your ears up and open.
Ed
I bought one of the remote kits from DIY Club. It was the 100K model using the Alps motorized pot. The PC board was designed to take a 12 volt DC signal and regulate it down to 5 volts for the pot. I just bypassed the 12 volt input and applied 5 volts from my Lightspeed supply. I then removed the solder on the pot signal pins and cut out the PC board area around them with a dremel. This allows you to isolate the pins for the rest of the circuit. Now wire up the correct pins like George had designed running 5 volts to them.
Tolu said:
As I have stated before this was the same way (series resistor/ shunt ldr MKI) I built the first MKI Lightspeed Attenuator around some 35 years ago, and the start of the production Lightspeed Attenuator a few years back.
It works but it's performance/sound quality is considerably down on the on the (series ldr/shunt ldr MKII) system.
Bass is tighter and overhaul more transparent and dynamic on the MKII version. The MKI sounds very much like a good old school tube amp, a bit soft, thickish in the bass and bit veiled and lacking in dynamics and transparency, but comfortable.
This is why all my MKI Lightspeed Attenuators were recalled and all upgraded to MKII status, and everyone of the owners said it was a vast improvement, except for one, who said now it is not very tolerant of hard sounding equipment anymore, that to me is a plus.
The MKI (series resistor/shut ldr) has a varying input impedance presented to the source and also a varying output impedance presented to the input of the amplifier, it also has a lot louder minimum volume, all these factors contribute to the reduction in sound performance/quality, also from memory it has a lot higher second harmonic distortion to it, that may be the reason for it's veiled thicker sound.
I think back in this thread a way I posted the distortion figures from Silonex on the difference between the MKI and MKII, and for a typical 1-2 volt input from a cd player and the MKI system had far greater 2HD distortion figure to that of the MKII version.
I wish I could have still made the MKI because it was so much less time consuming to make, but it is comprimised, and that won't do.
Cheers George
This is the post that gives the 2HD figures at CD (2v) input level for the MKI and the MKII configurations, as you can see the MKII has far less 2HD than the MKI.
http://www.diyaudio.com/forums/showthread.php?postid=1399965#post1399965
Cheers George
http://www.diyaudio.com/forums/showthread.php?postid=1399965#post1399965
Cheers George
Hi George
you are absolutely right. I haven't seen that the OptiVol is comparable to LS MkI.
I am very happy with my series/shunt version (mkII in your language
). Yesterday I have heard a new CD of Tord Gustafsen Trio - The Ground. The first minutes I was a little bit disappointed about the music but after 20 minutes the music began to fly. I am not sure if the reason was the warm-up perdiod of my power amp, the Chianti or a possible warm-up of the LS. Is there some kind of warm-up necessary for the LS? I have seen the Silonex parts have a high temperature dependancy (0,7%/°C).
My amp has 47k input impedance but my new one will have 262k so I am very excited how it fits with the LS. One problem is the low output power of my well sounding Playstation 1 of just 1.4 Veff. Some CDs have low recording level so the LS pot is at 70% to get a satisfying volume. I think I will optionally try the FET BOZ of John65. Haven't you wrote somewhere in this thread that Nelson Pass will develop a buffer for the LS?
Another question to the Silonex parts. All optocouplers of Silonex have no RoHS compliance. So, these parts are not legally allowed for manufacturers in the EU. Are there any substitutes with RoHS compliance on the market?
you are absolutely right. I haven't seen that the OptiVol is comparable to LS MkI.
I am very happy with my series/shunt version (mkII in your language
). Yesterday I have heard a new CD of Tord Gustafsen Trio - The Ground. The first minutes I was a little bit disappointed about the music but after 20 minutes the music began to fly. I am not sure if the reason was the warm-up perdiod of my power amp, the Chianti or a possible warm-up of the LS. Is there some kind of warm-up necessary for the LS? I have seen the Silonex parts have a high temperature dependancy (0,7%/°C).My amp has 47k input impedance but my new one will have 262k so I am very excited how it fits with the LS. One problem is the low output power of my well sounding Playstation 1 of just 1.4 Veff. Some CDs have low recording level so the LS pot is at 70% to get a satisfying volume. I think I will optionally try the FET BOZ of John65. Haven't you wrote somewhere in this thread that Nelson Pass will develop a buffer for the LS?
Another question to the Silonex parts. All optocouplers of Silonex have no RoHS compliance. So, these parts are not legally allowed for manufacturers in the EU. Are there any substitutes with RoHS compliance on the market?
Tolu hi,
The Lightspeed 's as I build them do like them to be left on 24/7, but with the volume control left at mid position when not in use.
As it is in this warmed up state that the channels are balanced out in the final calibration stage of the manufacture, when cold they can be out by a few db, this could be what you heard, bad imaging.
And sorry but there is no substitute for the NSL32R2S, that does the same job without some sort of negative compromise
And there will be a new DIY discrete buffer designed by none other than Nelson Pass for the Lightspeed soon, and this will solve any impedance mismatch problems with low input impedance power amps, here are the Links to the new Pass buffer reply.
http://www.diyaudio.com/forums/showthread.php?postid=1464609#post1464609
http://www.diyaudio.com/forums/showthread.php?postid=1465015#post1465015
Cheers George
The Lightspeed 's as I build them do like them to be left on 24/7, but with the volume control left at mid position when not in use.
As it is in this warmed up state that the channels are balanced out in the final calibration stage of the manufacture, when cold they can be out by a few db, this could be what you heard, bad imaging.
And sorry but there is no substitute for the NSL32R2S, that does the same job without some sort of negative compromise
And there will be a new DIY discrete buffer designed by none other than Nelson Pass for the Lightspeed soon, and this will solve any impedance mismatch problems with low input impedance power amps, here are the Links to the new Pass buffer reply.
http://www.diyaudio.com/forums/showthread.php?postid=1464609#post1464609
http://www.diyaudio.com/forums/showthread.php?postid=1465015#post1465015
Cheers George
George has taken to nagging me on when the buffer will be
out.
Patience.
The work is done, the graphs are all labeled, but the article is
still being written.
The piece is not a focus on the Lightspeed Attenuator (tm),
rather it deals with some arcane aspects of optimizing the
performance of discrete buffers. I'm sure you will find it useful.
out.
Patience.
The work is done, the graphs are all labeled, but the article is
still being written.
The piece is not a focus on the Lightspeed Attenuator (tm),
rather it deals with some arcane aspects of optimizing the
performance of discrete buffers. I'm sure you will find it useful.