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
Knghifi, glad you found the LSA a good listen. There is something that a good tube preamp does that is very enjoyable indeed, and the VACs being some of the finest. I went back and forth quite a while with my Joule 150 Signature Edition (which is supberb)but for my taste, I enjoyed the LSA every bit as much, so for the price difference I could not justify keeping the Joule, given that I have the Atma-sphere combo for cooler months. The LSA/RM10 I will use in the hot and humid Baltimore summers. I guess what I'll say for now, is that the LSA/RM10 combo is a killer pre/amp combo for less than $2,500 where 35 watts is enough power. If I were an audiophile on a limited budget it would be my number one choice, and with the right speakers maybe where budget is no limit too.
12-28-10: Fiddler
Knghifi,

Question. Are you listening to the LSA with new RCA IC's?
Fiddler (Threads | Answers | This Thread)

Both RCA ICs are dealer demos and I've logged ~250+ additional hours on them so are fully broken in.
Pubul57, now it's cold, just cleared 18" of snow and heating oil is up $1 a gallon since last refill, it's a good excuse to shop for a very hot and big mono tube amp again :-)