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Lightspeed Attenuator - Best Preamp Ever?

The question is a bit rhetorical. No preamp is the best ever, and much depends on system context. I am starting this thread beacuase there is a lot of info on this preamp in a Music First Audio Passive...thread, an Slagle AVC Modules...thread and wanted to be sure that information on this amazing product did not get lost in those threads.

I suspect that many folks may give this preamp a try at $450, direct from Australia, so I thought it would be good for current owners and future owners to have a place to describe their experience with this preamp.

It is a passive preamp that uses light LEDs, rather than mechanical contacts, to alter resistance and thereby attenuation of the source signal. It has been extremely hot in the DIY community, since the maker of this preamp provided gernerously provided information on how to make one. The trick is that while there are few parts, getting it done right, the matching of the parts is time consuming and tricky, and to boot, most of use would solder our fingers together if we tried. At $450, don't bother. It is cased in a small chassis that is fully shielded alloy, it gets it's RF sink earth via the interconnects. Vibration doesn't come into it as there is nothing to get vibrated as it's passive, even the active led's are immune as they are gas element, no filaments. The feet I attach are soft silicon/sorbethane compound anyway just in case.

This is not audio jewelry with bling, but solidly made and there is little room (if any) for audionervosa or tweaking.

So is this the best preamp ever? It might be if you have a single source (though you could use a switch box), your source is 2v or higher, your IC from pre-amp to amp is less than 2m to keep capaitance low, your amp is 5kohm input or higher (most any tube amp), and your amp is relatively sensitive (1v input sensitivity or lower v would be just right). In other words, within a passive friendly system (you do have to give this some thought), this is the finest passive preamp I have ever heard, and I have has many ranging form resistor-based to TVCs and AVCs.

In my system, with my equipment, I think it is the best I have heard passive or active, but I lean towards prefering preamp neutrality and transparency, without loosing musicality, dynamics, or the handling of low bass and highs.

If you own one, what are your impressions versus anything you have heard?

Is it the best ever? I suspect for some it may be, and to say that for a $450 product makes it stupidgood.
pubul57
georgehifi's avatar
georgehifi
10,312 posts
 
09-21-11: Agear:
1:George, is the diode effect measurable? What does it do of rather what does it distort?
2: Paul asked the million dollar question above: what are the effects of gain? Does it produce distortion?
3: I did try the LSA with a SS amp (TRL Samsons) with 68K input impedance and the sound staging flattened. I have experienced the same thing when running the amps directly with my source. What is this about George?:Agear

1: Diode effect is the very lightweight pin point touch contact of the metal wiper in a volume control on the resistive track in any volume control, and also on some switches, this creates the diode effect, which has a rectifying (change ac to dc)effect on the ac music signal trying to pass through it. Even Hervé Delétraz of the Dartzeel NHB-18ns also acknowledges it half way down the page here and he also uses the Lightspeed volume control in this preamp to eliminate it.
http://www.stereophile.com/content/dartzeel-nhb-18ns-preamplifier-page-2

2: All active circuits produce distortion/colouration whether they have no gain or unity gain.

3:By going directly from your source to your poweramps you are not adding or subtracting anything to that source. The perfect "mythical" active preamp is "a straight wire with or without gain", it doesn't exist.
If you insert a preamp that sounds different/better to your ears to this, you are introducing either a coloration or distortion that you prefer, which is a band aid fix, you should have a source that does not have to have this expensive band aid fix.

Cheers George
teajay
1,702 posts
 
Hi Charles1dad,

Thanks for your comment. Really like the "pompous windbag" description about good old George! Mr. Tsuda is not only one of the highest regarded designers and builders of Japan, but is a total gentlemen on a personal level.

I'm still waiting for what Tony's response is going to be to George's condescending remarks about Mr. Tsuda and the CF-080 preamp. I know that you have a friendship with him and great regard for this preamp, so what's your position now? Let us know.
unsound
7,333 posts
 
I don't have a dog in this fight. I just have a curiosity about an interesting approach. When did making a design criticism become synonymous with a personal attack?
teajay
1,702 posts
 
Hi Unsound,

On a post by Grannyring a few days ago on this thread he paraphrased the esscence of George's position. Anyone not in agreement with either his theoretical prespective or did not think his LSA sounded better then any passive or active linestage, if certain impedance conditions were meet, were the following: 1) Have a tin ear 2) like distortion. 3) in it for the money only 4)LSA is the absolutely the standard.

If these don't come across as putting anyone down who disagrees with him, I would like your assumption regarding the nature of his remarks. Specifically, his remarks towards Mr. Tsuda that he gathered from his anonymous "tube gurus" that, "if you are serious about valves" you would never use them like Mr. Tsuda does in his CF-080 preamp implies that this world renowned designer is an idiot for not agreeing with good old George's " tube gurus". One of the oldest forms of knavery in a debate is to share very nasty implied information by saying that it was proposed by someone else, not the speaker, to get the dig in and than avoid the heat from the audience. I doubt if good old George would even discuss this with anyone, why should he, he already knows everything about any design flaw in any preamp in the world, which means if its not his LSA its inferior and a waste of money and time.

fiddler
581 posts
 
Teajay wrote, "I will also never directly reply to any of your statements that might include me in the future because it would be a waste of my time."

How about wasting everyone else's time? Ever think about that? But nooooooo - it's all about me!
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