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
I will chime in. First my sysyem has been built to be passive friendly. I have had the Bent Tap, Placette, Silverstone magnetic passive to name a few.I purchased the Lightspeed that is advertised here on Audiogon. I agree with both Pubul57 and Clio09 the Lightspeed is truly special. It is the only passive that I have owned that outshines all other preamps passive, solid state or tubed that have graced my system.
Grannhyring, just to give you some context, my view of the Lightspeed is as a current and former owner of several highly regarded tube amps from Lamm,ARC.Joule, CAT, and Atma-sphere. Not that it proves anything, but I would not like this thing if it was in the least bit small, sterile and thin relative to anything. If the tube pres I have owned, and still own, are not the very best, they are close. The fact that this thing is $450 can hurt it for those use to 10K preamps.

Alas, it is not for everyone with its one single-ended, single input, but this thing does not sound like any of the stereotypes of passives, it has the signature of clean water, letting the source connect to the amp with minimal interference, without loss of any apparent bandwidth, or dynamics. It is not a bandaid preamp that will fix whatever isn't quite right or to once's taste in the rest of the system. A great source with a great amp and speakers are where this preamp will work best, even in the company of $$$$ components before it or after it. My feeling has always been that the preamp should be as neutral as possible with the coloration one prefers coming elsewhere in the system - making it more universally easier to use in many different system contexts.

I hope this unit is used by someone at RMAF so everyone can actually hear it and decide for themselves if it provides the type of sound they can be happy with. It would be nice if there were a 30-day trial, but I'm not sure if the low price and the long-distance transportation would make that viable - it is certainly light enough to ship around.