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.
If it's a new one, far as being fixed under warranty, ah, yes that would be out the window.

If you decide to do it, do not use the nylon insulating washers that come with rca's. You must make sure that all 4 x of the metal bodies of the new rca's are in electrical contact with the back panel.

And be careful the black anodising on aluminium chassis is an electrical insulator, so leave the burrs of the rca holes sticking up as they contact the rca's body.

Cheers George
Thanks George,I am quite happy with the unit as is,maybe down the road I'll try the new RCA, so that all contacts are rhodium to rhodium,just the OCD part of my brain talking out loud.The tips about what to do are most appreciated by me and anyonelse thinking about mods.
Hello again George, still loving m LSA and I did add a TeraDak PS to the mix.

At first I thought I heard a big difference vs. the wallwart but now I am used to it but I am staying with the TeraDak. Yes that red led is BRIGHT and be carefaul as the face plates are sharp. I hid my unit under my bed and my wife stepped on it and sliced up her toes very bad...

Curious how this Nelson Pass unit compares to the is a link to some circuit diagrams:
I hid my unit under my bed and my wife stepped on it and sliced up her toes very bad...

I am not going to ask because I don't even want to know.
Photonman, good news that you prefer the Teradac, am I reading right that you think it's a little better than the wall wart you have, if so in what way? And do you know if your wall wart was linear or switch mode?

As for Nelson Pass and that buffer. Many thanks to him as he first developed it for the Lightspeed Attenuator back in 2008 so that it could then drive some of his amps that had low input impedance that customers owned who wanted to use the Lightspeed with it. Those amps for memory had around 10 or 20kohm input impedance.

Here is the link to the 2008 post and circuit diagram for the Lightspeed he developed.

Cheers George