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

Showing 4 responses by rgs92

Does the Lightspeed sound different than the Placette?
I tried a Placette, and it did sound very open and really "not there", but then I went back to my tube preamp and there was some sort of magic sound with the tubes that I could not give up. I guess the tubes add something, but what they add sure sounds nice.
Yes, I have a solid state Luxman amp.
The combination of my tube preamp and the Luxman is extraordinary. So I think you are right. thanks.
Above, Georgelofi mentioned the Rothwell attenuators. I tried these (both XLR & RCA versions) trying to reduce the gain of my preamp and they sounded terrible, blunting things a lot.
Am I doing something wrong?

Any thoughts on if the Lightspeed might be more transparent than the Rotwhells in this application.

(Though they did work as advertised, cutting the gain and letting me get a proper volume level with my stepped volume control.)

(I've had other related posts on my gain reduction issue, so forgive me for this. Thanks.)
Thanks again Pubul. I actually have 2 amps, an Edge NL12.1 and the Luxman (both solid state), and the tube preamps I tried with these really makes a superb sound, w/o the heat & tube maintenance issues of powered tube amps.
Of course, this works better with speakers that aren't ruthlessly revealing or tipped up (but I don't favor these speakers anyway).

But really, the tube preamp makes all the difference with these amps, especially with some good NOS tubes, with life, palpability, gorgeous texture and tonality and lack of fatigue with detail simultaneously. The solid state and passive preamps were just flatter and not as engaging.