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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
mward
102 posts
 
I’ve been using the Lightspeed for several months now. I purchased the dual volume control version to solve a balance problem in my room. It works great and is as transparent as advertised. I compared it to 2 other passive pre amps that I own, a Schiit Sys and a Tisbury passive. Swapping the 3 passives in and out, and running the source straight into the amp revealed that the 2 other pre’s altered the original sound ever so slightly. The Lightspeed sounds the same as the source going straight in. I still like the other 2 passives, but the Lightspeed won the transparency test. My Lightspeed is feeding a 47 kohm input impedance, no problems there. I really like the flexibility the dual volume controls give me, and the performance has lived up to what I have read about it.

I’ve tried the iFi 12v power supply and a cheaper Jameco linear 12v supply. The difference wasn’t very noticeable in my system, but mileage may vary. I doubt I could tell them apart in a blind test.
georgehifi's avatar
georgehifi
10,312 posts
 
Hi mward, glad you like it, good that you gave it a few months before commenting on it. As for the " iFi 12v power supply "I think you are the first to try it, I had high hopes for this.
But as you say it's not that discernible from the standard wall wart. 
Sam Tellig (Stereophile) and myself found the same, even with pure battery power vs the standard wall wart. You sensed there was something different but couldn't say what, and you had buckley's telling the difference in a blind A/B.
PS: buckley's = Aussie slang for, "no way mate"

Cheers George 
mward
102 posts
 
Hey George, yeah the iFi just hasn't done much for my Lightspeed in my system. I feel like my system is resolving enough to pick out a bad recording pretty easily and to hear differences in cables, but I just couldn't spot the changes from this ultra quiet power supply if they exist. I almost felt like it made things a touch more reserved compared to the linear wall wart, but there is no way i could blind test prove it.  That was probably pyschological negativity toward a change on my part.  I like a lively system. I'm actually using the iFi right now and there is nothing wrong with it, just not a noticeable change for me.   My system doesn't have super sensitive speakers or a room designed for extremely critical listening though. I would be interested to hear about the iFi from someone with a very revealing system and dedicated room.  
ghosthouse's avatar
ghosthouse
4,291 posts
 
Glad to read the iFi iPower DC supply being discussed. I’m interested in using it in place of the as-supplied Auralic Aries Mini wall wart. I wouldn’t call my system extremely resolving, though I can easily hear changes in cabling. I could not, however, hear a benefit using the Audioquest Jitterbug. But, for $49 bucks from Music Direct and given their 60 day return policy it might be worth trying the iPower device. More likely to spend $49 as opposed $299 for the Auralic LPS. Am wondering if anyone other than mward has tried it. Tried searching discussions, this Lightspeed Attenuator thread was one of only two that came up. Thanks in advance for any input.
soundwise
39 posts
 
This Lightspeed sounded open, relaxed and showed me all  musical info that I have been missing for a long time, a real game changer..AN Dac 3 fed by msb digital cd rom drive into lightspeed then the CAT JL2...endless power and dynamics and i have not even matched the
impedance between devices yet...
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