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
Pub- Thank you for referencing some jazz. Yes, good-ol' Cannonball. Years ago, the guys in my band (the instrumentalists, I was the singer) got to sit-in with 'Weather Report' (Jaco was a friend of my bass player), and possibly coolest of all, Benny Goodman, Bobby Rosengarden(drums), and Bucky Pizzarelli(guitar), on what might have been Benny's last performance tour. You should hear some clarinet on vinyl thru a Lightspeed. When I use the Lightspeed for records, all I'm running is a "budget" Cambridge Audio 640P into it, behind a N.O.S Grace F9F mm on a Thorens TD160, and it's incredible. Re: "The Shootout" ... Whatever they were hearing was not the Lightspeed, unless there was a black hole nearby, with it's singularity pulling on, and distorting the light between the LED and the LDR. That might have given the Lightspeed the colorations and artifacts some needed ... in case the rest of the system was perfect, and soundless.
Anthony, if I read Ralph right, "Not to mention we haven't even discussed cables and as Ralph Karsten so often states, the coloration/artifact added by cables also has to be taken into account." what he has been saying, and given the fact that he makes and sells activ e tube linestages, I seem to hear him say that the reason for an active is to control the ICs, and that is the basic reason for an active, it's buffering of source-pre-cable-amp. Suggesting a preamp makes for a more universal tool in more systems, but that when the total capacitance is dealt with a passive is about as good as it gets, absent the need or desire for colorations of tone or "space".
There are a number of DACs on the market with 1V or greater output and digital volume control. Setting aside potential loss in resolution from the DVC, would the LSA provide better sound than direct-to-amp?
Is it the case that one a digital volume control is fully open, no attenuation, there is no loss in resolution? That was my understanding, but I am not technically proficient.
Yes, if the control is wide-open, or at least above a certain level, there is no loss in resolution. Assuming you were able to use/keep the DVC at a level above which there was no loss in resolution, would there be a benefit in using the LSA?