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 meant to say 50kohm input impedance or higher for the amp, not 5kohm - that would not work at all:)
You know how I feel.

Even with the Atma-Sphere S-30 I own where the sensitivity rating is nearly 3V this unit performs exceptionally well. I have used it with VAC Auricle Musicblocs and a Music Reference RM-10 as well. In each case its performance is consistent. I don't even have my Slagle Autoformer box in the system anymore.

The sound from the Lightspeed flies in the face of all the negative attributes that you hear people comment on regarding passive preamps. I am convinced anyone predisposed to active preamps that hears the Lightspeed in their system (and assuming proper system matching) will experience a reality check. At its price point there is not much to lose in trying one. I've dumped $450 (and much more) on interconnect cables that never came close to the price to performance value the Lightspeed provides.

Okay, back to our regularly scheduled program.
Money back trial? These passives have always disappointed me compared to a great active tube preamp. They tend to sound small, sterile and thin relative to a great tube active unit.

I have not heard this one, but have heard other highly touted ones.
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.