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
If I knew that was an option and the $$$ difference was marginal, I wold have gone for that - always good to control balance to deal with unbalanced recordings, rooms, and occassionaly speakers.
"I received an anonymous email saying if your wondering why it didn't get into "Class A" just have a look, nothing below 10K, it will never happen."

I'm not sure that is correct. If I'm not mistaken, products like PS Audio HCA-2 amplifier, the Musical Fidelity A3CR amp and the Benchmark DAC, all below the 2K price mark have earned the "class A" distinction at some point.
Pubul57, I know what you mean. It's my preference to have dual volume controls and when I ordered my LSA I just asked George if he could do it that way for me. I don't think it is an official option as George feels his stock design is best as is.

On another note, I have found that moving your listening position laterally one direction or another can act as a "balance control" too. We're not talking much distance here, maybe less than an inch or two and small increments make a difference.
Dual L&R controls in every PDF broucher I send out, is the only option I do. It's a $30usd option, but I tell everyone who inquires about it they are not as user friendly as the single stereo pot. As for different cd level volume change, you have to get the balance right again.

Cheers George