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
Both the mogami and the soundsilver are well under 100pf/ft. I wonder then what explains the dramatic difference I hear? Perhaps the difference was the length my tubed phono stage was seeing? Its output impedance is 1.2kohm, high for the LSA, I know.

Cables are mysterious to me.
Banquo363 The 1.2kohm for the phono is very high and should not be an "ideal" match with the Lightspeed, but it will not be harmful to anything either.
I have quite a few customer with dac's and phono stages with output impedances this high with tube output, and they say they couldn't care if it's not a 100% match as they are over the moon with the sound that they are getting with them into the Lightspeed Attenuator.

Cheers George
Grannyring, my cables are diy. It consists of silver-gold (from Mundorf, Germany) with wbt-plugs, 1/2 m. Formerly it was 1,5 m. And the ss poweramps? I wish I knew, a "wizard" has done it, not me.
batalok
Am I right in believing that non-ideal impedance match between phono stage and LSA results in a attenuation of the high end? Perhaps it hasn't bothered me because of my old ears?