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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
 
You have no constructive critisism Teajay, all you try to do is to get this thread shut down with your personal attack.
Not once have I attacked you personally just questioned the Ohms Law compatibility of components in your system that have not been properly addressed in the specs they have presented, and the voodoo that surrounds them.
agear
1,362 posts
 
George, is the diode effect measureable? What does it do of rather what does it distort?

Paul asked the million dollar question above: what are the effects of gain? Does it produce distortion?

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?
charles1dad's avatar
charles1dad
10,250 posts
 
Teajay,
Well said!
This pompous windbag compared to Mr. Masa Tsuda, are you kidding? No contest.
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
1,691 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.
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