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
As a photographer, I always preferred working with black and white film. Simpler, easier to develop, and the end results always seemed to stand out better than equivalent color shots.
The LSA has its own sonic signature in my system. I can hear the input/output wire flavor of its internal wiring. Grounding the unit also changes its voicing.
"I can hear the input/output wire flavor of its internal wiring." Now that is pure, imagine the effect of all the wiring, capacitors, resistors, and solder points in a complex, two-box, mega-weight preamp -- might obscure the sound of the internal wire. I find some Jamesons also changes the LSA's voicing - a ver yrevelaing device.
I just got through reading Sam's Space in the October issue of Stereophile and have to give the old boy for nailing why this thread really says the same thing over and over again and gets no were really at all.

Tellig has really changed his position that the best preamp in no preamp at all. Remember, he gave great praise to the LSA, yet comes to the conclusion that it ultimately leaves something out of the music that only an active preamp can provide in most systems.

Now, Paul would call this either a pleasant added distortion or it just is some euphonic change that gets in the way of the "pure signal", yet when I asked him way he uses some of the most "colored" IC's and speaker wires to muck up this "pure signal" coming from the LSA in his system he never did answer that question. This total thread, besides being a free advertisement/promotion of George's product, is techno-babble going over and over why the purity of the LSA or passives in general is objectively the only way to reach the truth of the music, and any active preamp just an out dated expensive waste of years gone by.

I totally accept that many passives including the LSA offer great performance for the price, but to say that they are on the same sonic level as world class reference active linestages for some factual/objective scientific reasons is just a realization regarding what is personal taste and system synergy in different systems for different people.

So, Sam just flipped from no preamp is the best preamp to why many music listeners would still invest their money in an excellent active linestage really shows why this thread is really a discussion that is a closed circle of logic developed by true believers regarding the LSA and passives in general. Take a look at Tellig's piece and tell me what you think.