Lightspeed/B1/TVC
Uriah - I have a Promitheus Dual Mono TVC, a B1 Buffer and a Lightspeed (as you know) - I would rate them in the reverse of that order.
They all are fine devices and I will keep all three of them so that ocassionally I can get a different perspective on my system, plus there is the matching issue especially with the LS which means that with certain amps (Nelson Pass for instance) I will need to use the B1 as a true buffer after the LS.
Possibly the only way to improve the LS would be to remove it from the chain and let the system run flat out, assuming that impedances match.
I have already ordered one more set of matched LDR's - I think I will need another set (playing around with some ideas - like building a music centre!!
Having seen your recent postings about costs could you please adjust the cost of this new set to reflect the increases in the previous set- cannot have you losing money doing us all a favour.
Regards
Alan
udailey said:
Uriah - I have a Promitheus Dual Mono TVC, a B1 Buffer and a Lightspeed (as you know) - I would rate them in the reverse of that order.
They all are fine devices and I will keep all three of them so that ocassionally I can get a different perspective on my system, plus there is the matching issue especially with the LS which means that with certain amps (Nelson Pass for instance) I will need to use the B1 as a true buffer after the LS.
Possibly the only way to improve the LS would be to remove it from the chain and let the system run flat out, assuming that impedances match.
I have already ordered one more set of matched LDR's - I think I will need another set (playing around with some ideas - like building a music centre!!
Having seen your recent postings about costs could you please adjust the cost of this new set to reflect the increases in the previous set- cannot have you losing money doing us all a favour.
Regards
Alan
Re: Lightspeed/B1/TVC
Very useful post, Alan!
The only missing thing to the list would be the JBOZ
http://www.diyaudio.com/forums/showthread.php?s=&postid=1834363#post1834363
AlanElsdon said:
Very useful post, Alan!
The only missing thing to the list would be the JBOZ
http://www.diyaudio.com/forums/showthread.php?s=&postid=1834363#post1834363
Slightly off topic, I was attempting to set up a matching jig for the LDRs and can echo Uriah's comment about these were the poorest devices being manufactured 
I have been trying to "perfect" my matching process, but matching these devices is really hard. These devices are very sensitive to the power supply. Even with 2 regulators (7812 and then 7805), I could still measure the voltage varied by 10mV during the day, and 10mV will make a big different in the measurement, no kidding!!
I set up a 100K pot + 200K pot in series so that I could adjust the voltage for matching easier and also see the range of resistance when such pots are used. I found out that when the pots were fully attenuated, I could get a reading of 1.2M to 600K through out the day. This is the difference the 10mV can make!!! IMHO, to match these LDR's, it is very important to use the same voltage across the devices (LED pins) unless you have a very very precised power supply that can be accurate and stable down to 1mV because a series of fixed resistors will still vary the voltage.
So far, I am still playing with the first 12 LDR's. If matching means within 20%, then I have found 2 candidate LDR's. With another 38 to go, I have no doubt to find more to make a quad. Since I plan to use 2 pots, one per channel, perfect match isn't really that important, but I do want to know the painstaking of dealing with these devices. Seriously, if you are not prepared to spend hours and hours to do the matching, buy from Uriah, these little devils can drive you nuts
I have been trying to "perfect" my matching process, but matching these devices is really hard. These devices are very sensitive to the power supply. Even with 2 regulators (7812 and then 7805), I could still measure the voltage varied by 10mV during the day, and 10mV will make a big different in the measurement, no kidding!!
I set up a 100K pot + 200K pot in series so that I could adjust the voltage for matching easier and also see the range of resistance when such pots are used. I found out that when the pots were fully attenuated, I could get a reading of 1.2M to 600K through out the day. This is the difference the 10mV can make!!! IMHO, to match these LDR's, it is very important to use the same voltage across the devices (LED pins) unless you have a very very precised power supply that can be accurate and stable down to 1mV because a series of fixed resistors will still vary the voltage.
So far, I am still playing with the first 12 LDR's. If matching means within 20%, then I have found 2 candidate LDR's. With another 38 to go, I have no doubt to find more to make a quad. Since I plan to use 2 pots, one per channel, perfect match isn't really that important, but I do want to know the painstaking of dealing with these devices. Seriously, if you are not prepared to spend hours and hours to do the matching, buy from Uriah, these little devils can drive you nuts
Thats the truth.
I have a helpful tip that I have not yet tried. Pick a single LDR. Label it. Measure it and record room temp at time of measurement. Measure as many LDRs as you can right now when room temp is same. When you go to measure again try to get room temp the same then get your labeled LDR and measure it again. Does it measure the same as it did when you first measured it and all your other measured LDRs? If so then commence with measuring your LDRs again. If not then you will not find true matches.
I am quite skeptical that 20% is anything worth calling a match. If we are talking about resistance of 80 and 100R then maybe because it wont A: effect overall impedance and B: it will be so loud you wouldnt hear it anyway. If we are talking about 5K and 4K this is no good and you will need a very large multiturn trimmer to bring channels to balance.
edit: Fred I see what you mean. After 12 the closest you have is 20%, not that 20% was good enough. Still figure I should leave the post so others get an idea of good/bad matching. Also for anyone wondering, I think Fred is going to 1.2M and 600k more out of curiosity than anything. You dont need to do this. See below...
Another tip.. my measurements produce good matched pairs. I measure at 1k, 10k, 20k, 40k. I dont go all the way up to 80 or 100k. Have not needed to. But I did just get some 100k 25turn trimpots I would like to try out and will probably use them in matching this batch. What I am saying is its not necessary to go to extremes if they are tracking well along this set of 4 measurements.
Uriah
I have a helpful tip that I have not yet tried. Pick a single LDR. Label it. Measure it and record room temp at time of measurement. Measure as many LDRs as you can right now when room temp is same. When you go to measure again try to get room temp the same then get your labeled LDR and measure it again. Does it measure the same as it did when you first measured it and all your other measured LDRs? If so then commence with measuring your LDRs again. If not then you will not find true matches.
I am quite skeptical that 20% is anything worth calling a match. If we are talking about resistance of 80 and 100R then maybe because it wont A: effect overall impedance and B: it will be so loud you wouldnt hear it anyway. If we are talking about 5K and 4K this is no good and you will need a very large multiturn trimmer to bring channels to balance.
edit: Fred I see what you mean. After 12 the closest you have is 20%, not that 20% was good enough. Still figure I should leave the post so others get an idea of good/bad matching. Also for anyone wondering, I think Fred is going to 1.2M and 600k more out of curiosity than anything. You dont need to do this. See below...
Another tip.. my measurements produce good matched pairs. I measure at 1k, 10k, 20k, 40k. I dont go all the way up to 80 or 100k. Have not needed to. But I did just get some 100k 25turn trimpots I would like to try out and will probably use them in matching this batch. What I am saying is its not necessary to go to extremes if they are tracking well along this set of 4 measurements.
Uriah
I have always found that matching to a reference is far better than trying to take absolute measurements.
It applies to resistors/capacitors/transistors/fets.
Pick an average device and use it as a reference.
Group your Duts by how far they vary from the reference.
Then pick a few Duts that appear to be close and compare them to each other.
You will get excellent and repeatable results is you take some care with designing and building the measuring jig.
It applies to resistors/capacitors/transistors/fets.
Pick an average device and use it as a reference.
Group your Duts by how far they vary from the reference.
Then pick a few Duts that appear to be close and compare them to each other.
You will get excellent and repeatable results is you take some care with designing and building the measuring jig.
Pricing for those new to the thread
I am paying 1.54 each for LDRs. After taxes and paypal fees they end up at 1.667 each.
Unbalanced Stereo Matched Set = 38.42
Balanced Stereo Matched Set = 100.22
Examples of quantities and pricing for unmatched LDRs including all fees:
25 = 50.44
50 = 93.97
75 = 136.29
100 = 179.22
Here is how it is calculated
((LDRs*1.54)(taxes of 8.25%)) +Shipping + DIYaudio Donation + Minimum PayPal fee of 30 cents
Multiply the whole thing by 3%
The prices above are final prices and include all fees. Here are the fees that are included in the prices above. Remember the prices above are your FINAL charge, no more.
I charge $4 for shipping anywhere in the world. Flat rate.
Required $3 donation to DIYaudio for each order is included in your price.
30 cents plus 3% of final total covers paypal fees.
There are now plenty of LDRs left so please dont hesitate to put your order in.
See my signature for a paper describing how to assemble the Lightspeed Attenuator and why it works the way it does.
Uriah
I am paying 1.54 each for LDRs. After taxes and paypal fees they end up at 1.667 each.
Unbalanced Stereo Matched Set = 38.42
Balanced Stereo Matched Set = 100.22
Examples of quantities and pricing for unmatched LDRs including all fees:
25 = 50.44
50 = 93.97
75 = 136.29
100 = 179.22
Here is how it is calculated
((LDRs*1.54)(taxes of 8.25%)) +Shipping + DIYaudio Donation + Minimum PayPal fee of 30 cents
Multiply the whole thing by 3%
The prices above are final prices and include all fees. Here are the fees that are included in the prices above. Remember the prices above are your FINAL charge, no more.
I charge $4 for shipping anywhere in the world. Flat rate.
Required $3 donation to DIYaudio for each order is included in your price.
30 cents plus 3% of final total covers paypal fees.
There are now plenty of LDRs left so please dont hesitate to put your order in.
See my signature for a paper describing how to assemble the Lightspeed Attenuator and why it works the way it does.
Uriah
To be honest, I have yet to build a LDR passive, so I have no experience to translate the degree of matching to audible imbalance.
I did follow Uriah's procedures to do matching initially, but I just couldn't do consistent matching for a reasonably long duration with this many LDR's in the same condition. I am slow to say the least. The same LDR could have significantly different readings at all 4 resistance values with only 2 hours apart!!! I did that in my garage, and there is a thermometer. I knew the temp wasn't the factor. That why's I turned to measuring voltage after the regulator. The voltage just varied. So, instead of using the 4 fixed resistance values, I used 6 fixed voltages range from 1.40V - 1.57V. I use a trimmer to adjust to the 6 voltages. This is the best way to accommodate my slow action. Not sure this is the similar to the kind of jig that Andrew talked about. To me, this gives me the consistency because I know the resistance of the LDR's are measured at fixed voltages at the LED pins.
Sorry for not being clear earlier, when I said 1.2M - 600K, I meant the LDR's resistance was dropped from 1.268M at 1.403V to 768.5K range at 1.412V, and my pot was at full attenuation in both cases. The difference was that I took measurement once in the morning and once at night. For the same LDR in a different range, I got 194K at 1.45V to 97.9K at 1.46V. As you can see, the voltage of the power supply change can really affect the measurement quite significantly.
I did follow Uriah's procedures to do matching initially, but I just couldn't do consistent matching for a reasonably long duration with this many LDR's in the same condition. I am slow to say the least. The same LDR could have significantly different readings at all 4 resistance values with only 2 hours apart!!! I did that in my garage, and there is a thermometer. I knew the temp wasn't the factor. That why's I turned to measuring voltage after the regulator. The voltage just varied. So, instead of using the 4 fixed resistance values, I used 6 fixed voltages range from 1.40V - 1.57V. I use a trimmer to adjust to the 6 voltages. This is the best way to accommodate my slow action. Not sure this is the similar to the kind of jig that Andrew talked about. To me, this gives me the consistency because I know the resistance of the LDR's are measured at fixed voltages at the LED pins.
Sorry for not being clear earlier, when I said 1.2M - 600K, I meant the LDR's resistance was dropped from 1.268M at 1.403V to 768.5K range at 1.412V, and my pot was at full attenuation in both cases. The difference was that I took measurement once in the morning and once at night. For the same LDR in a different range, I got 194K at 1.45V to 97.9K at 1.46V. As you can see, the voltage of the power supply change can really affect the measurement quite significantly.
Fred you were quite clear and I was glad that you posted your experience. I was only saying that readings of such high resistance are unnecessary and I think you should focus on readings that will actually be used. For instance try matching with resistance readings on the LDRs of 10k or less using resistors in series with 5VDC. Those series resistors should be from 1k-40k or maybe a bit higher but thats all. Think of having fifty chances to get the same reading over a 1k-50k spread then think of having fifty chances to get the same reading over a 1k-300k spread.... You may have a pair that match very well in the useable range but you will not have good luck finding that match up in the 1MOhm region. This is supposed to replace a 10k pot so aim for 1k-10k and you may have better success.
Uriah
Uriah
A DIYer sent me an email and I asked if I could post his comments. He said that was fine.
Here are a few lines of his opinion on the Lightspeed:
I have liked the B1 - best until the LightSpeed.
also
I decided to use my second set of LDRs in the simple method described by yourself and George - at first I thought I had got it wrong but on connecting to a cd player and a headphone amp I was astonished to hear a rather beautiful sound. So over the next few days it will be putting this into a nice little box and sticking it into my main system.
I always appreciate it when you guys/gals use my LDRs to build the circuit George has shared with us and then comment on how wonderful it sounds. The matching lets me give back to DIY and the profit lets me participate
Thanks to all of you for making this fun.
On the not so fun front I got to testing last week. The whole batch of 408s were measuring to low. I spoke with Allied and they are sending me a new bag of LDRs. Thankfully they are cooperating. So back to the grind when I get them. In the meantime I have been researching current sources and labeling your shipping boxes.
If someone is still interested but has not yet let me know please do. You have lots of time to get in on this buy and I plan to buy another 500 or so. You will not be left out and the buy is NOT over.
Remember the price includes all fees. 38.42 for matched stereo set shipped ANYWHERE in the WORLD.
100.22 USD for Balanced set. Thats the final cost for both. Many people ask does that include paypal fees does that include shipping. YES. Final price. That also includes a $3 donation to DIYaudio. I will donate this money on July 15th when I ship.
Uriah
Here are a few lines of his opinion on the Lightspeed:
I have liked the B1 - best until the LightSpeed.
also
I decided to use my second set of LDRs in the simple method described by yourself and George - at first I thought I had got it wrong but on connecting to a cd player and a headphone amp I was astonished to hear a rather beautiful sound. So over the next few days it will be putting this into a nice little box and sticking it into my main system.
I always appreciate it when you guys/gals use my LDRs to build the circuit George has shared with us and then comment on how wonderful it sounds. The matching lets me give back to DIY and the profit lets me participate
Thanks to all of you for making this fun.
On the not so fun front I got to testing last week. The whole batch of 408s were measuring to low. I spoke with Allied and they are sending me a new bag of LDRs. Thankfully they are cooperating. So back to the grind when I get them. In the meantime I have been researching current sources and labeling your shipping boxes.
If someone is still interested but has not yet let me know please do. You have lots of time to get in on this buy and I plan to buy another 500 or so. You will not be left out and the buy is NOT over.
Remember the price includes all fees. 38.42 for matched stereo set shipped ANYWHERE in the WORLD.
100.22 USD for Balanced set. Thats the final cost for both. Many people ask does that include paypal fees does that include shipping. YES. Final price. That also includes a $3 donation to DIYaudio. I will donate this money on July 15th when I ship.
Uriah
I doubt it. Actually it has caused some fuss over there and the VP of Silonex wants to talk to me about it. Allied is concerned that their stock is junk and told me about 10 minutes ago that they are not sure if they will ship to me yet out of the bags that they do have.
Another thing. All 549 of the ones I will return have masking tape on them. I doubt they will sit down and remove the masking tape from each one. I put the tape on so I can label them.
Also, I believe this is contained to the one bag and NOT to the 408 batch. This is what I will tell Silonex when I talk to them. Maybe this will, hopefully, get me an "IN" with Silonex and maybe I can get some better quality. Who knows. Anyway, I got that bag sealed from Allied. Massive bag never had been opened. I have got 408's before in different bags and they measured differently. I had always been under the impression that 408 was a date code and it seemed to me that batches generally match up better within the batch than outside of that batch, this throws that assumption into question.
So I will have more info when I talk to Silonex. You guys will know everything I talk with them about.
Want to see something neat? Just go ahead and google "silonex lightspeed" and see if you dont get 1350 hits with lots of traffic. We are already in "hacked gadgets" and that same blog has found its way to dozens of other sites. Also it it Twittered about which I found neat. The Lightspeed build thread over on DIYaudioProjects is the most active project right now with average 300 hits per day. How many products have already spawned off of the Lightspeed circuit? My guess is dozens whether they advertise it or not. Some do. Check out www.myth.rs for example. Check out the Ska Optivol, check out 6Moons for preamps that use it as well as EnjoyTheMusic who have also reviewed pres that involve some sort of LDR. Pretty powerful stuff but still under the radar somehow.
Uriah
Another thing. All 549 of the ones I will return have masking tape on them. I doubt they will sit down and remove the masking tape from each one. I put the tape on so I can label them.
Also, I believe this is contained to the one bag and NOT to the 408 batch. This is what I will tell Silonex when I talk to them. Maybe this will, hopefully, get me an "IN" with Silonex and maybe I can get some better quality. Who knows. Anyway, I got that bag sealed from Allied. Massive bag never had been opened. I have got 408's before in different bags and they measured differently. I had always been under the impression that 408 was a date code and it seemed to me that batches generally match up better within the batch than outside of that batch, this throws that assumption into question.
So I will have more info when I talk to Silonex. You guys will know everything I talk with them about.
Want to see something neat? Just go ahead and google "silonex lightspeed" and see if you dont get 1350 hits with lots of traffic. We are already in "hacked gadgets" and that same blog has found its way to dozens of other sites. Also it it Twittered about which I found neat. The Lightspeed build thread over on DIYaudioProjects is the most active project right now with average 300 hits per day. How many products have already spawned off of the Lightspeed circuit? My guess is dozens whether they advertise it or not. Some do. Check out www.myth.rs for example. Check out the Ska Optivol, check out 6Moons for preamps that use it as well as EnjoyTheMusic who have also reviewed pres that involve some sort of LDR. Pretty powerful stuff but still under the radar somehow.
Uriah
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.