But the moderators made it clear that they only want discussions of Georges lightspeed (and not all the successive variants) in this thread.
Are you saying that you tested and confirmed that the pot affects the lightspeed?
this thread is about Lightspeed attenuator
and everything related to this design, known as Lightspeed, belongs here
different designs with only the use of LDR in common are best discussed in seperate dedicated threads
if not, everything ends up being messy
thats how it is with every other topic
please respect what serves the forum and its members best
try to keep things organised and in good order
do that and it will all go well
its as simple as that
and everything related to this design, known as Lightspeed, belongs here
different designs with only the use of LDR in common are best discussed in seperate dedicated threads
if not, everything ends up being messy
thats how it is with every other topic
please respect what serves the forum and its members best
try to keep things organised and in good order
do that and it will all go well
its as simple as that
Hoping not to "stoke the fire" here about quality of pots -
I have done quite a few things to the basic Lightspeed that has noticeably changed the sound of the completed Attenuator in circuit, but have not found any difference at all by using different pots that vary the power to the LEDS.
I've tried out a number of different pots (basic and good quality), a 26 position stepper and the Twisted Pear "Joshua Tree" - no change in the SOUND itself.
I have done quite a few things to the basic Lightspeed that has noticeably changed the sound of the completed Attenuator in circuit, but have not found any difference at all by using different pots that vary the power to the LEDS.
I've tried out a number of different pots (basic and good quality), a 26 position stepper and the Twisted Pear "Joshua Tree" - no change in the SOUND itself.
I can confirm that I am referring to the current control dual 100k log law pot used in the Lightspeed by George.
A few say the quality of the pot in the LED part of the circuit affects the quality of the sound coming from the LDR part of the circuit.
I came in with a suggestion that might remove the pot as an unknown in the sound quality chain.
If a pot removal pair of resistors did improve the sound quality, then we could start a discussion on how to get the best out of the Lightspeed.
A few say the quality of the pot in the LED part of the circuit affects the quality of the sound coming from the LDR part of the circuit.
I came in with a suggestion that might remove the pot as an unknown in the sound quality chain.
If a pot removal pair of resistors did improve the sound quality, then we could start a discussion on how to get the best out of the Lightspeed.
This makes complete sense.
The only time that this wouldn't theoretically be the case is if a carbon pot were so old and damaged that the carbon track had developed dead spots preventing a constant supply of juice to the LEDs. I can live with the possibility of that happening a few years down the road...
For me, one of the big advantages of the Lightspeed over the DACT stepped attenuators is having a nice clean sweeping volume control, and not a clicky-clack one that confuses my wife
women!.. a clicky-clack one that confuses my wife
Why do we need them on this Earth?
OOPs, is that more than a little sexist? I love them all.
Andrew,
Thats the perfect solution to that question. If you guys would put a 10k on the Shunt LDRs from the 5V supply and then put a 90k on Series you could test and see if this is better than a regular pot.
Obviously any couple resistors that add up to 100k would work. Just make sure that the Shunt is higher than Series or be ready for high volume.
I agree Lucas. If we use a non-damaged pot there should be no noise to inject into the LDRs that is related to the pot even if it has a fragile wiper. As Andrew has mentioned several times the wiper wont handle much current so when you choose a pot you dont pick a .125W pot. I often use a .25W pot and I have not had one fail yet, but in reality the wiper should not be able to handle full current for long.
I like Alpha pots and RadioShack pots. Both less than $3. If they fail just replace them. It wont damage anything but you might have very low or very high volume until you shut off your amp depending on which wiper dies first.
Improvements in sound quality come from a very quiet supply. If you build a Lightspeed and wonder if you can improve it then give it some snubbing on the LED leads and 1000uf or more on input of your voltage regulator as well as a few low value film or tantalum to ground from each pin of your regulator, then 100uf or so on output of the regulator. I guarantee that is worth the extra $2 and 10 minutes work.
Uriah
Thats the perfect solution to that question. If you guys would put a 10k on the Shunt LDRs from the 5V supply and then put a 90k on Series you could test and see if this is better than a regular pot.
Obviously any couple resistors that add up to 100k would work. Just make sure that the Shunt is higher than Series or be ready for high volume.
I agree Lucas. If we use a non-damaged pot there should be no noise to inject into the LDRs that is related to the pot even if it has a fragile wiper. As Andrew has mentioned several times the wiper wont handle much current so when you choose a pot you dont pick a .125W pot. I often use a .25W pot and I have not had one fail yet, but in reality the wiper should not be able to handle full current for long.
I like Alpha pots and RadioShack pots. Both less than $3. If they fail just replace them. It wont damage anything but you might have very low or very high volume until you shut off your amp depending on which wiper dies first.
Improvements in sound quality come from a very quiet supply. If you build a Lightspeed and wonder if you can improve it then give it some snubbing on the LED leads and 1000uf or more on input of your voltage regulator as well as a few low value film or tantalum to ground from each pin of your regulator, then 100uf or so on output of the regulator. I guarantee that is worth the extra $2 and 10 minutes work.
Uriah
She has NEVER noticed any difference in any audio tinkering I've done. She can't tell the difference between pairs of speakers whatsoever and thinks I am wasting money on the emperor's new clothes with every new component. She's right that this is an obsessively perfectionist exclusively male hobby, but she has no compassion for how darned addicted I am!
I have to secrete money and put it aside to secretly buy new projects - it's tragic fella's! Tell me I'm not alone!
Sorry, I don't believe her; I think she's misleading you. My wife used to say the same thing but I've managed to get an admission out of her that she does hear the difference.
I think she probably does hear the difference but doesn't care or thinks that the hobby is silly and that you should be happy with what you've got.
In this last bit, I'm dead sure that you're not alone.
You Sir are not alone and are in a group of similar situated husbands that is staggering in the number of its members.
I only am personally acquainted with one woman who has similar hearing to her audiophile husband. And they are supposed to hear better. My wife does notice the difference the Lightspeed makes, but she couldnt care less. Ipod all the way! LOL
Uriah
I only am personally acquainted with one woman who has similar hearing to her audiophile husband. And they are supposed to hear better. My wife does notice the difference the Lightspeed makes, but she couldnt care less. Ipod all the way! LOL
Uriah
You are not alone...
And I used to test all my new builds on my ex-wife. Women have better hearing than men and if you can find one that will co-operate they can be quite helpful.
Hi guys
I am trying to track down the source of a slight hum from my F5. My LDR attenuator in a separate case to my amplifier.
Would anyone happen to have a good grounding layout?
I had a quick scan through this thread yesterday but couldn't find anything
Thanks
Hi Richard,
I don't have an F5 earthing plan, but the following is an awesome guide to earthing chipamps and taught me about the importance of forcing the directional flow by using differently sized wires, and also how to eliminate earth loops:
http://www.diyaudio.com/forums/chip-amps/118735-gainclone-hum-thump-problems-solution.html
It worked for me and I'm a doofus!
Certainly worth taking a look at.
Hi Richard,
I don't have an F5 earthing plan, but the following is an awesome guide to earthing chipamps and taught me about the importance of forcing the directional flow by using differently sized wires, and also how to eliminate earth loops:
http://www.diyaudio.com/forums/chip-amps/118735-gainclone-hum-thump-problems-solution.html
It worked for me and I'm a doofus!
Hi Lucas
Thanks for the link
I'll double check my F5 tonight.
Regards
Guys-
I have some matched sets of LDRs, a board from Uriah, and an alps remote control set up on the Swap Meet section of this site. Sorry for the cross post, but I figured it would benefit someone if I posted here as well, as there are so many posts in that section.
Anyway, turns out I bought some other gear, which has a volume control, so I just don't need the items. Hopefully someone here can benefit.
Just search for my name. Thanks
I have some matched sets of LDRs, a board from Uriah, and an alps remote control set up on the Swap Meet section of this site. Sorry for the cross post, but I figured it would benefit someone if I posted here as well, as there are so many posts in that section.
Anyway, turns out I bought some other gear, which has a volume control, so I just don't need the items. Hopefully someone here can benefit.
Just search for my name. Thanks
My kit or someone else'?
Google Docs
George's schematic is at the first page, my schematic is at the last page.
Uriah
Google Docs
George's schematic is at the first page, my schematic is at the last page.
Uriah
If one wanted to "preattenuate" before the LDR attenuator in order to reduce overall signal level to match a high gain amplifier and efficient speaker system, would it be best to use a two-resistor voltage divider before the series LDR, or just a single series resistor in line with the series LDR?
Any opinions?
Any opinions?