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 3 responses by esmith904

Sharing my new experience with the Lightspeed Attenuator. I've recently been researching what key upgrade I could make to my mid-fi Adcom setup (Cal Audio Labs Icon II CD, GDA-700 DAC, GFP-565 preamp, GFA-545 II amp, AR9LSi speakers) in an attempt to approach hi-fi sound. After much web searching and reading reviews, I determined replacing the Adcom GFP-565 preamp was where I'd get the most sound improvement. However, most of the recommendations I could find suggested I'd need to step up to $3K-4K active preamp or give a passive a try. Luckily, I stumbled across this thread with glowing reviews how the Lightspeed is as good or better than very expensive active preamps. My experience so far has blown me away. I didn't know recorded music could possibly sound this good. The sound is super clean, clear, more 3 dimensional, and has more bass at low volume. The music seems to have more impact from individual instrument sounds at moderate listening levels. Seems like I can feel the music more.   I can really tell a difference in the sound of cymbals now have a clear metallic shimmer vs. a fuzzy sizzle. Everything just sounds better across the spectrum. I'm buying another one for my office system. I feel like I've joined the secret Lightspeed club. It's hard to believe something this good is not that widely known.
tradeontheweb thanks for the guidance.  I may try the battery option too as a fun experiment.  I've started out powering the Lightspeed with a Teradak power supply. 

I hadn't done any upgrades to my setup in about 10 years since I recapped my AR9LSi speakers with audio grade film caps.  I thought I was done, but started sensing something was holding me back recently.  I started researching what folks were saying about the components that I already had and discovered folks saying the Adcom GFP-565 was not very good.  Glad I found the Lightspeed.  It totally makes sense that putting  more active components between the music source and the amp risks adding more noise to the signal.  It would have been another long journey to buy and try a bunch of different active preamps.  The Lightspeed has also rekindled my audio bug too.  Will be looking  at further upgrades or mods to my other components, but the Lightspeed will remain at the core.
Hi clio09, I've purchased two U9 Teradak power supplies from the same seller and link you posted.  They both work great with the two Lightspeeds that I've recently acquired.