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
Hasn't made the website yet, but working on it. We need to officially dress one up and get pictures of it. Similar concept to the Decware CSP as the output voltage is adjustable, but we've added another feature that allows you to set up the output of the preamp using meters on the front panel. So when adjusting the output voltage so you can actually see how you are affecting the sound. If you want a hotter sound you can have that, something a bit mellower you can have that too. Tubes are mounted on the back panel so the preamp has a slim look to it.
Just bought a LSA and got hooked up for 5 hours. got the best sound ever from the system with loads of beauties, transparency, tonality (especially bass), and dynamics... This is the component that blows me away from all the perspectives of value, performance, and design concept. Salute to George and thanks all in this thread for the guidance.
Just in case some are wondering, Tristone (Lei) ordered a dual mono unit, these seem to be gaining popularity as it gives audiophiles a balance control being separate left and right volume controls.
I still recommend the stereo unit if your room and system are balanced from left to right, as dual mono can be a little less user friendly to use, as the famous Audible Illusions 3A's used to be if you ever lived with one.

I know some her have built their own Lightspeed clone from the circuit boards that are available on DIY forum, so I have posted up how to modify the circuit board for dual mono use should you wish to do it. Here is the link.
http://www.diyaudio.com/forums/analog-line-level/80194-lightspeed-attenuator-new-passive-preamp-443.html#post2944737


BTW Tristone thanks for the rap!!

Cheers George