Lightspeed Attenuator a new passive preamp - Page 294 - diyAudio
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Old 17th January 2010, 03:22 AM   #2931
jleaman is offline jleaman  Belgium
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Quote:
Originally Posted by udailey View Post
If there are no objections to fresh starts lets help people build their Lightspeeds.
I dont think any of the major contributors to the thread will object to that. I am sure we will find out.
If you are reading this for the first time please take the time to read at LEAST the first 5 pages of this thread. There is absolutely NO passive preamp out there that matches the clarity, neutrality and absolute beauty in sound of the Lightspeed. This is a wonderful thread with good information in it but if you want the short of it read the first 5 pages and also visit the diyaudioprojects link in my signature where you can learn how to build one in a very short time.
Whether you buy LDRs from me makes no difference. I will assist you fully in building your pre amp. Dont think you are now going to be alone on this thread. I think there will still be lots of help but if thats not the case you will get assistance from at least me.
Sincerely
Uriah


Wish i had a kit! WINK WINK!!
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Old 17th January 2010, 02:43 PM   #2932
udailey is offline udailey  United States
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Well to my knowledge there is no such thing as a Kit to the Lightspeed and I will not be the first guy to offer them.
What I am attempting to do here is keep this thread alive and keep people interested in DIYing their own Lightspeed.
I think any more talk in the negative tones we have experienced in the past few pages is counterproductive and I am trying to steer this thread back toward a more positive attitude where people feel free to ask questions about building their own Lightspeed in their own basement for their own use.
If I have any place to say so on this thread I would hope that we can turn the boat around and talk exclusively about George's Lightspeed circuit without mention of kits, etc which can do nothing but upset him further.

SO, again if you are new to this thread or have read it several times but have not built this circuit... DO you have any idea how easy this is to build!!?? It has got to be the simplest circuit for a new DIYer to dive into and will absolutely build a hunger for more DIYing as the results prove beyond a shadow of a doubt in any system that DIYing your own audio can provide incredible results.
To illustrate how easy this is to build I am going to look for a little pic I posted a year or so ago that has helped a lot of schematically challenged folks built the Lightspeed.
Lets keep it positive and on track Pic coming up, have to search hard drive..
Uriah
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Old 17th January 2010, 02:47 PM   #2933
udailey is offline udailey  United States
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Default pics of how to build the Lightspeed

Here is that pic I drew a year or so ago..
Attached Images
File Type: jpg LSdrawing.jpg (97.0 KB, 438 views)
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Old 17th January 2010, 02:49 PM   #2934
tinitus is offline tinitus  Europe
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Hi Udailey, you previously mentioned that a simple non regulated supply performed good, and maybe even better than a regulated
Do you still favour a non regulated supply
And at which voltage
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Old 17th January 2010, 02:57 PM   #2935
udailey is offline udailey  United States
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Default Etch a board

You can etch your own boards. Or use perfboard. Etching is easy. Just downloard ExpressPCB or another free pcb software and then download pdf995. You design your pcb and then print it to a pdf file with pdf995. Then you print from pdf onto that overhead projector plastic sheets. You might have to try 4 or 5 times but its worth it. For even better chances of success try using HP toner. It matters a little
Anyway get some copperclad fiberglass board from ebay. Scrub it with Scotchbrite and then clean it with nail polish remover. Keep your oily fingers off of the copper now. Put the plastic sheet toner side down on the board. Put a sheet of paper over top of it and use some masking tape on the sides to hold it all in place. Maybe even use some little plastic vices or similar to hold all still. Then use the wifes iron and iron the image with decent pressure for a few minutes. Remove the paper but no the plastic. Put the rest in a cold water bath.
After a minute or so slowly remove the plastic in the water.
More later
Breakfast now.
Uriah
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Old 17th January 2010, 03:13 PM   #2936
udailey is offline udailey  United States
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Okay, now you probably have toner on the copper and it probably didnt transfer well. Try again and again. Soon you will have a process that works and you will be able to build your own boards whenever you want as long as they are single sided. Some people do double sided. Thats really hard.
So its transferred. If there are any tiny areas that did not transfer you can use a sharpie marker and fill them in. The sharpie has plastics in its ink and this will keep the copper from disolving in the acid bath. Thats right, acid bath.
You will now need a container bigger than your board and several inches deep. Plastic and you will never use it to eat out of again. You pour Muriatic Acid in it and also H202 (Hydrogen Peroxide). About a 4:1 ratio. Put the board in and keep this outside. Even with fans this is NOT an indoor project and I am not just being overly careful. If you breathe this in you will seriously hurt your lungs and the damage after a few breaths can be permanent. Do not stand downwind. Do not allow your family around this. I got it on my hands several times and it will yellow your skin instantly but is not a big deal. The breathing in and getting the fumes in your lungs or eyes is what is a big deal. Keep a lot of water around for a few reasons. One, you can dunk your hands in it if you get it on your hands. Two, you can wash the pavement if you get it on the pavement. (It will etch cement) and Three you will need to dunk your board in the water when its done etching to remove the acid.
Okay so how long do we etch the copper? Well just keep an eye on it. Heat makes it go faster but nothing happens so fast that you wont catch it. You will be able to see it echting away. I drill a hole in my board and tie a piece of plastic string to the hole so I can remove the pcb without getting my hands in the wash/acid. So pick up the board by the string and inspect it every few minutes and more often toward the end when its really obvious that the etching is nearly done.
This is a lot of fun, I think. I love having build my own boards. Its rewarding. It falls right into the geekiness of building audio and you can always brag about it
You will have to drill out the holes afterward and you can use regular drill bits but the Titanium bits are best and if you go to ebay you can find bits specifically for pcb drilling. Be careful as they are super durable up and down but will snap left and right.
Uriah
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Old 17th January 2010, 03:22 PM   #2937
udailey is offline udailey  United States
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Quote:
Originally Posted by tinitus View Post
Hi Udailey, you previously mentioned that a simple non regulated supply performed good, and maybe even better than a regulated
Do you still favour a non regulated supply
And at which voltage
Hi Tinitus,
My opinion has changed several times
Recently I have found that voltage does not matter. Keep it under 100mW. A lot of people will point to figures on Silonex' site stating that somewhere aroung 3-5V is best for distortion. This is utterly wrong. The documents on their site are misleading, but not intentionally misleading. The voltage that produces distortion is the voltage through the resistive material and not the LED.
I have been using 17V recently. Its fine.
The problem I find is that noise gets from the LED into the resistor. So its not that the LED is creating noise but if there is noise coming through, or generated by, your supply this gets to the LED and transfers to the resistor. I am not yet sure how to take care of this so a noisy mains creates a noisy signal.
At this point I have no preference between regulated and non regulated per se but I prefer building the quietest power supply you can. If you can eliminate hum, keep the ground quiet, get rid of lightswitch and refrigerator pops this will do the most good with your Lightspeed.
I have not yet tried caps on the leads of the LEDs. A friend of mine is using 220uf and snubs then and then puts a 1MR resistor across the snubber. He has not tried anything different though so we dont know if he is really benefiting from it or not. I put a .1uf across the LED leads but for some reason it seemed to let the DC through and the LED went dark. I tried no further but I do think it merits closer inspection. I just havent done that yet.
Uriah
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Old 17th January 2010, 03:57 PM   #2938
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I'll chime in....

I used Uriah's diagram to build my LS onto perfboard, but my very first experiment was hard-wired. Uriah supplied the matched LDRs and I supplied the other 10 or so bits! George's circuit is a great performer, and we're lucky he has shared it with us. I matched my LDR channels by looking at the outputs on the 'scope, at my listening volume position.

I built my effort into an old Trends TA-10 box (I murdered the original innards ), and squeezed in a super-regulated power supply as well (ALWSR - google for info). The lot is fed by a 12V linear wall-wart. Simples!

So, in summary:

No kit (or pcb) needed.
Definitely an easy first project.
Results far exceed effort or expense.
Use a clean power supply.

Cheers

Jon
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Old 17th January 2010, 04:45 PM   #2939
udailey is offline udailey  United States
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Was at the grocery store and it hit me that I left out some info.
I do prefer regulated at this point. The reason is that if you drop down to low voltage or low current any changes in mains voltage on a non regulated supply will change the impedance AND volume. I think it would have to happen (the voltage drop) pretty fast to be noticed but if you for instance turn your LDRs to 10k-20k depending on that particular LDRs efficiency and then drop the supply voltage by .01V the resulting resistance will be several hundred ohms so you can imagine a non regulated supply that loses 10V on the mains would make enough difference in resistance to change the volume. While I have not experienced this, only experimented with it, it is certainly feasible that it would/could happen.
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Old 17th January 2010, 04:57 PM   #2940
maximus is offline maximus  Scotland
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Default Lightspeed remote control

Hi Folks,

Out of interest I made provision on the VCCS board to fit my Z17 type low noise mini shunt regs in place of the TL431 shunt regs. These are a lot quieter than the TL431. The current source section of the Z17 is not fitted to the mini reg as it is acting as a super Zener only. The S17 ultra-low noise mini regs can also be used to replace IC3 which was specified as MC7812CT. Applying these regs gives a very quiet control system with excellent supply line rejection over a very wide bandwidth. Quiet feed equals quiet lightspeed.

Regards
Paul
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