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
Georgelofi, I think you misread my comments and want to clarify for you. You stated;

“Grannyrig check your facts before you double swear it was 100k input.”

I actually said this;

“I can tell you the Samson amps by TRL do have the input impedance spec mentioned already. I can tell you I tried the Lightspeed with Atmasphere Ma1’s that have an input impedance of 100K ohms”

As you can see I said the Atmasphere amps had a 100K input impedance, not the Samsons. The input impedance that Knghifi mentioned was 68K and I referred to it. I and others simply stated it was higher then 47K.

Hope this helps clarify.
Pubul57
The TRL amps are all SS? Not hybrid?
Pubul57

Samsons are all solid state 68k, fet input, dc coupled.
Cheers George
Apologies to Grannyrig, you did not state the Samson was 100k, I misread the statement you made, it was the Atmasphere you were eluding to.
This has got a bit out of hand, because I had mentioned "was the Lightspeed seeing the ideal load".
It was and was beaten out by the $14,000 VAC Signature MKIIa in Knghifi's setup, I wait for future posts Knghifi after the dust has settled and all has burnt in.

Cheers George
$13,550 is a lot of spare change. The way things are going right now I might be able to turn that into $50,000 here in Las Vegas by the end of football season:)