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Old 16th October 2012, 08:08 PM   #4831
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All that should be fine, the OTL'S are probably over 47kohm input, so all is good.

Cheers George
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Old 16th October 2012, 09:20 PM   #4832
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All that should be fine, the OTL'S are probably over 47kohm input, so all is good.

Cheers George
Yes, the amp is 100k
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Old 17th October 2012, 02:25 PM   #4833
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George,

First of all I have to thank you again for your generously release your design and all the helps follow through.
I have this volume to compare with my double choke 26 preamp and I can tell you that I love this volume more, a lot more. The density of sounds is one of the kind and it is, as I said on the last post, so smooth, liquid and detail. Background is very dark and very deep.
I highly recommend this design. This is simple enough for the newbie like me.


Albert
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Old 17th October 2012, 10:56 PM   #4834
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Thank you Albert for your kind words, and your views on the sound. I wish all the emails were all like that, instead of some that say I am trying to ruin the preamp industry (one guess which sector those came from).
Most sources these days have so much output that they can send 99.9% of poweramps into clipping, so why the need for hideously expensive preamps with their extra gain and active circuitry that only adds colourations and distortions.

I believe and so do many owners that if your source (cdp dac etc) is low in output impedance, which most industry standard sources are.
And your poweramps input impedance is >47kohms (which is the industry standard) or higher (tube generally are much higher).
That the Lightspeed Attenuator the most transparent/dynamic uncoloured way of transferring the source's signal to the poweramps yet with control over the volume.

The only way this was bettered (only slightly)to mine and others ears, was when I demonstrated the source directly plugged into the poweramps with no Lightspeed Attenuator in the signal path. This source had a digital domain volume control and was use in it's top 25% of full output, any less than this and the dreaded bit stripping occurred taking the resolution from 16bit down to 14bit and further the lower the digital volume control was taken below 75% of it's full output. But the trouble with using it this way is that most systems would want the digital volume control at less than 60% for normal listening level where then you would loose resolution down to 12bits or less. So the Lightspeed Attenuator is the closest way to having a direct connection between source and poweramp there is.

Cheers George
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Old 18th October 2012, 01:08 PM   #4835
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instead of some that say I am trying to ruin the preamp industry (one guess which sector those came from).
Everyone has right to talk and I suggest him to pay more attention to his product instead. If he can't sell his product to people it means that he should pay more time to improve his product instead of saying bad words to hurt others that he shouldn't. Hifis /cars are the same. people have money and didn't want the hassle and they pay mega bucks for the brands that they prefer, and most importantly they can show off to people who admire. A good and not pricey compact car can do the same and take to to the location you want, nothing wrong with that.
Most sources these days have so much output that they can send 99.9% of poweramps into clipping, so why the need for hideously expensive preamps with their extra gain and active circuitry that only adds colourations and distortions.
Like I said, you aim at those with ears and they sell their products to somebody with money and love to show off that is all. I the one don't want to spend that kind of money for the product that I don't like. This is why I start DIY. But don't make me wrong, I have ears.

I believe and so do many owners that if your source (cdp dac etc) is low in output impedance, which most industry standard sources are.
And your poweramps input impedance is >47kohms (which is the industry standard) or higher (tube generally are much higher).
That the Lightspeed Attenuator the most transparent/dynamic uncoloured way of transferring the source's signal to the poweramps yet with control over the volume.
I totally agree.
George, Be patient and don't mad with whatever words out there. You're just aiming at those with ears. Let them decide what is good and bad. I've been making many amps and speakers for the last 45 years but I still calling myself a newbie for the reason that I'm still learning everyday, there is still lots of new things that I don't know out there. Lightspeed is the one. At the beginning, I had a wrong idea in mind that I should go with some complicated design to have good sound. Now I strongly believe the KISS form. Let people out there making whatever they think is good for the moment, and I am sure they'd come back to the KISS form later on.
People who don't believe, please make one for yourself and try.

Albert
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Old 1st November 2012, 08:46 AM   #4836
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finally finished the reading of almost 500 pages!
George, thank you very much for sharing this splendid idea! Uriah, thanks for giving the opportunity of building Lightspeed to us mortals

I'm keen on building my own!
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Old 1st November 2012, 09:25 PM   #4837
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Originally Posted by albertli View Post
I believe and so do many owners that if your source (cdp dac etc) is low in output impedance, which most industry standard sources are.
And your poweramps input impedance is >47kohms (which is the industry standard) or higher (tube generally are much higher).
That the Lightspeed Attenuator the most transparent/dynamic uncoloured way of transferring the source's signal to the poweramps yet with control over the volume.
Albert
I must agree. I am using George's invention now for 5 years and continue to be amazed at the sound. As I continually improved the source, the lightspeed showed itself to be completely transparent. This was with a tube output DAC and a SS amp that has lower than the recommended impedance. I am now building a tube amp and look forward to experiencing the full potential of the lightspeed.
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Old 2nd November 2012, 02:39 AM   #4838
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I must agree. I am using George's invention now for 5 years and continue to be amazed at the sound. As I continually improved the source, the lightspeed showed itself to be completely transparent. This was with a tube output DAC and a SS amp that has lower than the recommended impedance. I am now building a tube amp and look forward to experiencing the full potential of the lightspeed.
My 6C33C OTL with 100k input - designed by Hans - sounds so good that I haven't had heard before. I even gave up my AN DAC and the choke load 26 pre-amp for the lightspeed.
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Old 2nd November 2012, 07:39 AM   #4839
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. . . an SS amp that has lower than the recommended impedance.
I recently added a second upgraded Quad 303 power amp to my system - its input impedance is nominally 20k so my Lightspeed-circuit volume control is driving 10k per channel. To my surprise and despite breaking all the rules, it works (and sounds) fine.
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Old 2nd November 2012, 08:07 AM   #4840
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Just regarding my stated minimum input impedance of 47kohm or higher, this is only a comfort guide.
So long as the source cdp/dac is low output impedance, the Lightspeed will still be comfortable looking at 20kohm poweramps.
As we conducted a 20 audiophile listening test with a tube amp that was specially modded to have a switchable input impedance from 300kohm down to 10kohm and could be switched while playing.
We started with the high 300kohm input and came down in increments and not until we got down to 33kohm, only then did 5 or so of the audiophiles think they heard a very slight compression, and even then they were not 100% sure.
Many Lightspeed users that I know are using it with 20kohm poweramps and still say that even if it's not at it's optimum, it's still sounds better than their expensive active pre's they were using.
And thanks very much for the positive comments dtses, wlowes, albertli and ryelands.

Cheers George
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