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
That's good news, glad you sought it out, hope that dicky amp didn't feed anything strong back into the ldr's in the Lightspeed, as the ldr's are in direct coupled contract with any amps input stage via the interconnect..

Cheers George
Best No- No such thing.

The Active MP-1 Pre-Amp has bettered any Passive iv ever tried. Not tried this one thou but doubt it can better An Atma-Sphere

I own an Atma-Sphere MP-3 and while it is quite a fine preamp the Lightspeed is right there with it. In fact in some of my system set ups I prefer the Lightspeed, while others I prefer the MP-3.
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The sources volume should be controlled up and down that’s all. (nothing added or subtracted)

The well known saying, "the best preamp should sound like a piece of wire" not adding or subtracting anything from the sound of the source, and if you don’t like it, you don’t like something else in the system, better to fix it.

The closest in order to "sounding like a piece of wire" and being "the best preamp", most transparent of all without colourations or distortions are:

1: Direct source to amp connection, if!! (the source has a digital domain volume control, and it’s not use below 75% of full, as not to "bit strip the music")

2: All passives (except tvc’s), if the system permits impedance compatibility (most do)

3: Active preamps + tvc's, which have colourations/distortions, (that’s why they all sound different), and may suit if finding the right one to mask the problems with source or system, but in doing so they ruin the transparency, and add colourations. (to me it’s better to fix the problems and have it all)

Cheers George