Hi Ben,
There is no 'latest' schematic. The one you mentioned is the most easily accessible and works really well. True, I am working on a circuit that has produced what look like really neat results on protoboard, but I need to take it to reality with a real pcb and in my system. It will take a while.
On another note..... I am 80% finished with my test fixture and everything seems really great so far. Its a little hard to get the LDRs in place but with this fixture its nice that I only have to insert them one time, run as many tests as I want with each LDR, and then be done.. so I can take that one setback along with the other advances and ease of use I get out of the set up.
Uriah
There is no 'latest' schematic. The one you mentioned is the most easily accessible and works really well. True, I am working on a circuit that has produced what look like really neat results on protoboard, but I need to take it to reality with a real pcb and in my system. It will take a while.
On another note..... I am 80% finished with my test fixture and everything seems really great so far. Its a little hard to get the LDRs in place but with this fixture its nice that I only have to insert them one time, run as many tests as I want with each LDR, and then be done.. so I can take that one setback along with the other advances and ease of use I get out of the set up.
Uriah
Not at all. I am gearing up for a new matching so you would be a part of that. Shipping I believe will be possible by Christmas since I will have that new test fixture and matching should be faster.
Shoot me an email.
A single ended set is 38.42 USD. That includes paypal fees, shipping and a $3 donation to DIY audio.
A balanced set is 100.22 USD and includes all the same fees and shipping.
If you want more than one set then your cost per set goes down. An EXTRA SE set would be 30.90USD and an extra balanced set would be 92.70USD.
Uriah
Uriah,
Ok will follow george's schematic first. I've seen a schematic where they have 2 capacitor accross the LED somewhere but I couldnt find it.
Just to be clear, for each set, 2 matched LDR will go on the series, and the other 2 will go for the shunt, is that correct?
When will you share the supply schematic
Best regards,
Ben
Ok will follow george's schematic first. I've seen a schematic where they have 2 capacitor accross the LED somewhere but I couldnt find it.
Just to be clear, for each set, 2 matched LDR will go on the series, and the other 2 will go for the shunt, is that correct?
When will you share the supply schematic
Best regards,
Ben
I have to approve my own supply Ben It works so far but I want to tweak it. I have it working on protoboard and the LDRs look like they are doing the right stuff, but I want to put it all together in a big chassis with pots instead of all resistors and tweak the heck out of it WHILE it plays so I can really be sure its doing what I thought it would do.
----------
In regards to your first question... YES
It works so far but I want to tweak it. I have it working on protoboard and the LDRs look like they are doing the right stuff, but I want to put it all together in a big chassis with pots instead of all resistors and tweak the heck out of it WHILE it plays so I can really be sure its doing what I thought it would do.----------
In regards to your first question... YES
Here is a link to my prototype I am working on. I am not giving away the circuit right now, but thought I would put out a teaser
Picasa Web Albums - Uriah - Desktop
Picasa Web Albums - Uriah - Desktop
Exactly You an actually use combinations from as few as 4 resistors from 0-1MOhm or more, but I found these precision Bourns pots salvaged from some other job for 2.25 each and they are working really well so I figured I would use 0-20k since these pots are 20k.
On another topic I got a few super precise pots in my voltage regulator for my matching jig and I have 0.000001V precision on that thing Now, actually I would say more like .00001V because at .000001 the 1 doesnt like to sit still but anything above that is rock solid. I can dial in LDRs to better than 40Ohm precision at 20k ohms and down at 100R on the LDRs I can change their resistance as precisely as .001R. I am waiting for some labels to show up to label the LDRs and I can start matching. In the meantime I am working on that circuit in the pic linked above.
Ri
You an actually use combinations from as few as 4 resistors from 0-1MOhm or more, but I found these precision Bourns pots salvaged from some other job for 2.25 each and they are working really well so I figured I would use 0-20k since these pots are 20k.On another topic I got a few super precise pots in my voltage regulator for my matching jig and I have 0.000001V precision on that thing
Now, actually I would say more like .00001V because at .000001 the 1 doesnt like to sit still but anything above that is rock solid. I can dial in LDRs to better than 40Ohm precision at 20k ohms and down at 100R on the LDRs I can change their resistance as precisely as .001R. I am waiting for some labels to show up to label the LDRs and I can start matching. In the meantime I am working on that circuit in the pic linked above.Ri
Just got a set built
I can not attenuate to a complete silent, is this expected? My trimpot which is 1k, its not working, full left or full right does not have any effect to the volume.
And on the minimum volume position, its still too loud, how can I modify this? I follow the schem on diyaudioprojects, and uriah's handrawn p2p schem which are the same.
Any tips?
Best regards,
Ben
I can not attenuate to a complete silent, is this expected? My trimpot which is 1k, its not working, full left or full right does not have any effect to the volume.
And on the minimum volume position, its still too loud, how can I modify this? I follow the schem on diyaudioprojects, and uriah's handrawn p2p schem which are the same.
Any tips?
Best regards,
Ben
Ben, It is normal that they will not attenuate to complete silent. The reason is that the shunt LDRs must go to 0 Ohms to be silent. They will only go to about 50 Ohms so we always have a level we can not go below. Everyone wants perfectly matched LDRs which makes sense on the surface but frankly its better to have perfectly matched series LDRs and perfectly matched shunt LDRs but to have shunt be of a lower value than the series because we want slower increase of volume. If you have perfectly matched quad then the volume will come on rather fast. To fix this I have tried two ways. I have used a single resistor or a single pot added to the regular Lightspeed circuit. Get a pot of the same value as your control pot or more. We are going to stick it in parallel with the section of your control pot that controls the Shunt LDRs. So on your Lightspeed circuit we have A W and B of each gang. A-W controls either series or shunt and W-B controls the other. Pick the one that controls shunt. Wire this new pot in parallel with the section that controls shunt. One of the two terminals on the new pot that you will use will be the wiper. You want full resistance between the wiper and the other terminal you use when you have this pot turned all the way left.
So wire it in. If you turn on your Lightspeed and you have it wired to the side of the control pot that controls series LDRs you will know instantly as it will be incredibly loud. If it is wired correctly it will be quieter instantly. Turning it to the right will decrease the volume because the shunt LDRs will be getting brighter and brighter having less and less resistance and letting more signal go to ground rather than to your amp.
Ben if this is hard to understand dont sweat it. I am more than happy to talk to you on the phone to help you or you can shoot me a few emails and I will walk you through it. Remember to try to use a pot that is close to the control pot's value. Since it is in parallel we know that instantly the shunt LDRs are going to be getting double the current they were before. Since you have your 100R resistor in place you still do not have to worry about cooking them. It wont happen. If you use a significantly lower value of pot then it will override the usefulness of the control pot because it will end up being the one in control as its value decreases the electricity will recognize its resistance more than the control pot. It might be fine for you but for ease of use try to pick one of similar resistance to the control. I probably sound like a broken record. Sorry Shoot me an email or keep it going here. Either is fine.
Uriah
So wire it in. If you turn on your Lightspeed and you have it wired to the side of the control pot that controls series LDRs you will know instantly as it will be incredibly loud. If it is wired correctly it will be quieter instantly. Turning it to the right will decrease the volume because the shunt LDRs will be getting brighter and brighter having less and less resistance and letting more signal go to ground rather than to your amp.
Ben if this is hard to understand dont sweat it. I am more than happy to talk to you on the phone to help you or you can shoot me a few emails and I will walk you through it. Remember to try to use a pot that is close to the control pot's value. Since it is in parallel we know that instantly the shunt LDRs are going to be getting double the current they were before. Since you have your 100R resistor in place you still do not have to worry about cooking them. It wont happen. If you use a significantly lower value of pot then it will override the usefulness of the control pot because it will end up being the one in control as its value decreases the electricity will recognize its resistance more than the control pot. It might be fine for you but for ease of use try to pick one of similar resistance to the control. I probably sound like a broken record. Sorry
Shoot me an email or keep it going here. Either is fine.Uriah
Hi Uriah,
Thanks for the tips. How about a schematic for whats your suggesting?
Im having trouble understanding the explanation to be honest.
Also, the trimpot react rather slowly, meaning when I turn it, the changes does not take effect until 3-4 seconds later, but the main dual-pot, reacts instantly, Im quite puzzled, is this expected as well?
I follow the schem exactly as in the diyaudioprojects.
Kind regards,
Ben
Thanks for the tips. How about a schematic for whats your suggesting?
Im having trouble understanding the explanation to be honest.
Also, the trimpot react rather slowly, meaning when I turn it, the changes does not take effect until 3-4 seconds later, but the main dual-pot, reacts instantly, Im quite puzzled, is this expected as well?
I follow the schem exactly as in the diyaudioprojects.
Kind regards,
Ben
Ben,
Lets try this.
Here is a link to one of my drawings. I know, its pretty sophisticated LOL
http://www.diyaudio.com/forums/atta...onex-ldrs-lightspeed-attenuator-lsdrawing.jpg
Anyway, see how the gangs of that pot are made of posts 1,2 and 3?
While your system is playing at low but not minimum volume... Put a low value (like 100R or maybe 1k, but kinda low) resistor across legs 1 and 3 of one of the gangs. If it gets quieter, then this is how you solder it in. You can use a set value resistor... or you can use a pot. This will quiet things down and make your increase of volume less dramatic. You can use either pot to change volume now. Either the main control pot, which will change series resistance or the new pot which will change shunt resistance. Or, you can use both once you get a handle on the math of what is happening. One nice thing is that now you can change the overall impedance of your LDRs which will give you a chance to find which impedance sounds best with your amp.
Ri
Lets try this.
Here is a link to one of my drawings. I know, its pretty sophisticated LOL
http://www.diyaudio.com/forums/atta...onex-ldrs-lightspeed-attenuator-lsdrawing.jpg
Anyway, see how the gangs of that pot are made of posts 1,2 and 3?
While your system is playing at low but not minimum volume... Put a low value (like 100R or maybe 1k, but kinda low) resistor across legs 1 and 3 of one of the gangs. If it gets quieter, then this is how you solder it in. You can use a set value resistor... or you can use a pot. This will quiet things down and make your increase of volume less dramatic. You can use either pot to change volume now. Either the main control pot, which will change series resistance or the new pot which will change shunt resistance. Or, you can use both once you get a handle on the math of what is happening. One nice thing is that now you can change the overall impedance of your LDRs which will give you a chance to find which impedance sounds best with your amp.
Ri
Ah ok, much clearer now. Thanks much, will try it.
That is the schematic that I follow as well. The 2 trimpots are the ones that react slow, 3-4 seconds for effect after I turn it, is that normal?
And at the lowest volume, I still cannot match the channels, 1 channel is very faint, but the other is still significantly louder while the trimpots are at the lowest setting.
Thanks again,
Ben
That is the schematic that I follow as well. The 2 trimpots are the ones that react slow, 3-4 seconds for effect after I turn it, is that normal?
And at the lowest volume, I still cannot match the channels, 1 channel is very faint, but the other is still significantly louder while the trimpots are at the lowest setting.
Thanks again,
Ben
Ben
At lowest volume the shunt LDRs have to be on all the way. This means they are in saturation and that means that you could give them infinite power and they will still only be at that resistance. They all have a different saturation point. So at full low volume chances usually are channel imbalance. You turn the pot just a tiny bit up and that goes away as they unsaturate and come into an area they can be controlled.
Not sure about your trimpot issue Ben.
Uriah
At lowest volume the shunt LDRs have to be on all the way. This means they are in saturation and that means that you could give them infinite power and they will still only be at that resistance. They all have a different saturation point. So at full low volume chances usually are channel imbalance. You turn the pot just a tiny bit up and that goes away as they unsaturate and come into an area they can be controlled.
Not sure about your trimpot issue Ben.
Uriah
Igor,
Please email me at diyldr@gmail.com and I will get you on a list. I had to redo my jig. It was working great with 12 and when I put it together for 120 the results were not as good as I would like. I redid the boards and will order them today so I am set back about a month. Ship around end of January. These boards should allow me to start responding to requests for parts immediately rather than after a few months.
Uriah
Please email me at diyldr@gmail.com and I will get you on a list. I had to redo my jig. It was working great with 12 and when I put it together for 120 the results were not as good as I would like. I redid the boards and will order them today so I am set back about a month. Ship around end of January. These boards should allow me to start responding to requests for parts immediately rather than after a few months.
Uriah
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