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
Just read the review on the Ypsilon active and passive preamp. Anyone compared the passive one to a LSA? Only a $25,500 price difference :-):-)
Knghifi, you do have to wonder how much better it can possibly be (if it is) - you really have to wonder about this market place; who really buys this stuff? 10 people in the world?
Tony, I only have a hard copy Stereophile sub and is in the current July issue. I've only skimped through MF review ... basically it best his reference, his darTZeel.
Well at least MF is comparing it to something a bit closer in price. Then again MF liked the LSA too, just wasn't high enough in cost to get Class A rating. I'm sure he'd look pretty stupid to the industry if he said a $500 component was comparable to one that cost $26k, but wouldn't it be interesting if that is what he privately felt;)

From the information I saw on the Ypsilon PST-100TA preamp it has two operational modes, each with a 150 ohm output impedance. One operates in unity gain and the other 20 dB of gain due to a tube output stage IIRC. Leads me to believe this is an active preamp all around, but I could be wrong, just not that much information to go on.