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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
georgehifi's avatar
georgehifi
10,312 posts
 
mickstuh
 Just to test before shelling out, I plugged my passive Schiit Sys into the Halcro. The Schiit outputs up to 5K ohm (not dissimilar I believe to the most the Lightspeed puts out).
Hi Mick, thank you very much for the glowing review, especially with your equipment the Lightspeed is keeping company with. I've tried to Google these speakers but found very little on these 100kg beasts have you a link to them?

As for the slight impedance mismatch, the worse scenario output impedance for the Lightspeed is around 2.7kohm, if the Schiit Sys is a 10kohm volume pot this should be about the same.

And yes even 2.7kohm output impedance into your Halcro's very low! 10kohm input impedance, it will be at a slight disadvantage, this is why you liked the extra drive the X10-V3 a little more.

But if the Halcro had say 33kohm or higher input impedance, you would probably have preferred the sound without the buffer in circuit. As the best buffer is no buffer still if you don’t need it.

Cheers George

esmith904
3 posts
 
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
43 posts
 
Welcome to the club esmith904 !
Your description kind of mirrors what I remember mine was, more than 10years ago now. I’d thought I was doing well with my system. Big Infinity Speakers, couple of Krell amps and a Cal CL-15 HDCD/CD player. I’d used a variety of solid state and valve preamps, including Musical Fidelity, Audio Research SP10 & 11 and most memorably, a very "microphonic" Supratek valve Pre. Some were great, some less so, but all imparted their own coloration to the sound.
I actually borrowed my first Lightspeed from a friend. On first sight, it wasn’t impressive at all compared to the monsters I’d used. But connecting and listening dispelled any concerns I’d had on the appearance. As you say, clarity, cleanliness and dynamics are there in spades. I don’t care what it looks like, I bought one there and then. At the price, it’s one of the real bargains in high end Audio and let’s face it - they’re few and far between!
I don’t know whether we’re in a "secret"club any longer, as I see more and more comments on it here and over at DiyAudio as well.
Anyway, nice to see another happy Lightspeed’er on here!
tradeontheweb
43 posts
 
BTW: esmith904

You can also try to power it using rechargeable battery power, (links are somewhere here to get one on eBay).
Most (including me) say it’s better than the wall wart, but there’s not much in it, just a feeling.
As they can’t explain what’s better, but it’s definitely worth doing as they are cheap to get.
esmith904
3 posts
 
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.
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