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Old 31st December 2013, 07:25 PM   #5201
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Quote:
Originally Posted by soongsc View Post
The Lightspeed method basically removes contacts from the signal path. I have two different LDR applications that begs to be assembled and tested, an I should be doing this in the near future. Other than lack of physical contacts, I think there are other qualities that I expect to see in measurements. Look forward to doing that.
Yes you will also be listening to Cadmium Sulphide instead of carbon or metal film, don't ask me if this is the magic of the sound. As well as no contacts (that may cause "diode effect on transients") in the signal path.

Cheers George
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Old 31st December 2013, 10:36 PM   #5202
wlowes is offline wlowes  Canada
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There is no question that at the end it is the resistive element that makes the magic by getting out of the way like few others can do.

The Lighspeed innovation is the fact that we use this resistive element and that it is convenient to alter the level of attenuation. But it is still the resistor that makes it possible for the signal to get thru without as much destruction that is typical of resistor based attenuation.

Again George, thank you for 6 years of Lightspeed joy. Happy new year.
Walter
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Old 31st December 2013, 10:56 PM   #5203
wlowes is offline wlowes  Canada
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Default Looking back would you do it the same?

George,
I recall you starting this thread in 2006 and early in 2007 you semi reluctantly revealed the secrets of the Lightspeed.

If you had it to do all over again, would you have kept it a secret or reveal the recipe to the DIY crowd?

I for one am glad you spilled the beans. I am a DIY guy, and would never pay $450 for a volume control let alone pay $20k for a premium linestage. OTOH
I have had great success and fun with DIY Lightspeed... For this I will forever be greatful.

I think there is a DIY market that is distinct from the finished product market. Without a lot of overlap.

In a perfect world, it would be great if you had patented this approach. It would have been great if it's clear superiority was recognized over the established art and that the audio industry moved to your innovation paying royalties as it went.

In this fickle world of high end audio innovation, I don't think that was going to happen. i have to think that by revealing the formula to the DYI community, your Lightspeed garnered some of the fame it deserves, and you likely got a continued run of customers as a result.

Back to the curiosity that prompted this post...

If you had it to do over again, would you have kept is secret or repeated history?

Last edited by wlowes; 31st December 2013 at 11:03 PM.
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Old 1st January 2014, 01:22 AM   #5204
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If I could of I would have patented it, but it's components were not new, it was just the way I used them back in the 70's, from lightmeter parts out of Hasselblad, Lieca and Nikon cameras.
If I was able to patent it i still would have given out how to do it for diyer's, just like Nelson Pass does, but I too then would have a team of legal hounds watching for anyone who was making them for monitory gain from his IP.

Cheers George
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Old 7th January 2014, 08:47 PM   #5205
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Those who have a Lightspeed Attenuator and wishing to try a different power supply instead of going battery. As linear wall warts are very scarce these days and let face it smp wall warts are noisy and are all that seem to be available especially in the US.
I've been shown this quite reasonable priced one which is a nice linear regulated product. They take Paypal and shipping is very fair.
Very nicely built, uses Panasonic FC caps, and comes with the correct lead, plug and polarity (2.1mm center positive). This is 9vdc @ 1A which fine for the Lightspeed Attenuator as it converts it down again with it's internal 5vdc regulator.
And has a bonus 5v usb port output for those wanting to power a 5v usb item.

TeraDak U9VA Linear Low noise Power Supply

Cheers George
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Last edited by georgehifi; 7th January 2014 at 08:54 PM.
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Old 7th January 2014, 09:23 PM   #5206
tinitus is offline tinitus  Europe
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not long ago I noticed some older pro/instrument gear that used the LDR as control element
can't remeber how old, and the LDR may have been added later
and now I have forgot where it was
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Old 7th January 2014, 09:38 PM   #5207
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Quote:
Originally Posted by tinitus View Post
not long ago I noticed some older pro/instrument gear that used the LDR as control element
can't remeber how old, and the LDR may have been added later
and now I have forgot where it was
Very common in modulation effects like fasers, noise gates, compressors and more. Even as volume control. Usually only implemented as a singe device in serie or shunt.
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Old 9th January 2014, 02:34 PM   #5208
soongsc is offline soongsc  Taiwan
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I was just reading a book by Walt Jung and came across a concept of the "negative resistance buffer". This reminded me of a circuit that seemed to have introduced lots of ontrovery in this thread a while back such that the part may have been removed. My question is, does anyone know where that part of the thread was moved to and has anyone tried the "negative resistance buffer" with the Lightspeed? Seems like a nice feature to built in.
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Old 13th January 2014, 10:33 PM   #5209
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For those that have an original MkII Lightspeed Attenuator

I found a very good priced very well made linear power supply for the Lightspeed.

TeraDak U9VA Linear Low noise Power Supply

It has all the goods like Panasonic FM caps and looks well built postage is very good as well, and PayPal can be used.
Reports have been very good compared to the wall wart, but I must say the comparison could have been made to a smp (switch mode) wall wart, which yes then it would be better than it.

AudiogoN Forums: Lightspeed Attenuator - Best Preamp Ever?

AudiogoN Forums: Lightspeed Attenuator - Best Preamp Ever?

As when comparisons were made to pure battery power a linear wall wart was still just as good. And Sam Tellig of Stereophile backs this up as well with his Lightspeed.

So if you are running your Lightspeed Attenuator with a smp (switch mode) wall wart you are not hearing the best from it.
It's very hard to pick the difference between smp or linear wall warts, as they look similar.

One good way is to get a little portable AM radio tuned off station low on the dial volume up and go near it, if it squeals like a stuffed pig you have a smp wall wart. Get rid of it and get a linear one or battery or the Teradac power supply.

Trouble is that it's getting harder to find linear wall wart these days as neither smp or linear are marked on them.

Cheers George
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Last edited by georgehifi; 13th January 2014 at 10:41 PM.
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Old 28th March 2014, 03:45 PM   #5210
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Hi, I've done a lot of reading about the lightspeed attenuator. I am very keen on building one, but where can I get a pair/quad of Matched LDRs for the Lightspeed Attenuator?

I contacted some (old) suppliers mentioned in the different threads but no luck there.

I will place a thread in the Swap Meet department.
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