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
Pubul57, now it's cold, just cleared 18" of snow and heating oil is up $1 a gallon since last refill, it's a good excuse to shop for a very hot and big mono tube amp again :-)
Hi guys and Knghifi, glad your enjoying the Lightspeed Attenuator, you've put it up against a very expensive ($14,000) in the Vac Signature pre, I'm over the moon it held it's head up high against to it. One question Knghifi the poweramp TRL Samson you used for the comparison, it's a solid state amp and I have looked everywhere for it's input impedance and nowhere can I find it, as the Lightspeed Attenuator likes to see 47kohms or higher for the poweramp it's feeding. If the TRL is lower than this you have still not heard the Lightspeed at it's best, and heaven forbid it may beatout the VAC Signature if it sees an amp with the input at 47kohms or higher. Does anyone know the input impedance of the TRL Samson?

Cheers George
My LSA keeps getting better with time (I've had it less than a month), so I'm withholding final judgment until later. Definitely needs warm up use time to sound its best (the second side of a record, and beyond, always sounds better than the first side played).

That said, it delivers beautiful sounds right now and no way I would sell it. And, yes, George is a standup guy who is very quick to answer questions and delivers as promised.
Specs for TRL? Like asking Rolls Royce for horespower data and getting "sufficient" as a response. Just kidding, but their site offers very little information beyond price.
I believe the TRL amps are over 47k ohms, somewhere in the 65k ohm range, maybe higher.