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
I've had my Lightspeed several months now and just tried something that gave me a great improvement. I've had the wall wort pluged into my dedicated ac line. I pluged it into my ballanced power conditioner and it made a huge improvement. The improvement was as good as when I pluged my cd player into the conditioner. More 3 dim. soundstage, better separation of instuments, lower noise floor etc.
I'm now thinking of trying a 12v battery supply to power the LED. Has anyone else tried a ac cond. or batery supply and if so, was it an improvement for you ?
I prefer a battery, but I cannot say why, if I did a blind test I could not say which was which.
Sam Tellig of Stereophile says the same, he prefers the battery when he know which is on, but cannot say why either.
Go to ebay and type in "12v Lithium Ion rechargable" make sure with the seller that the lead that comes with it is a 2.1mm plug and center is positive. If center is negative you will cause damage to the Lightspeed.
These 6800mAh Lithium batteries are good for 2 weeks before needing a recharge, they are already overkill so no need to get bigger.

Cheers George
I do not prefer the battery. I cannot say exactly why but with the battery it sounds a bit lifeless and more clean. Without the battery it sounds more vivid. Probably I like the result of a "dirty" power.
Regards
batalok
My LSA has arrived it now does volume control for my Esoteric X-03 into a pair of tube Acoustat servo amps on my Acoustat X speakers.
Previously I was using the line inputs of my Manley Steelhead into the Acoustats.
The walwart is plugged into a Hydra 8,which is connected by a Shunyata Annaconda power cord into a FIM recptacle on a dedicated 20 amp line.The Acoustats are on another 20 amp line using more Annacondas into a Furutech GDX-gold receptacle.
The esoteric has an Annaconda digtal power cord going direct into the FIM 's other receptacle.
The LSA sits on 3 roller blocks atop the hydra and is plugged into one of the Hydra's digital recptacles.

Sorry about the long winded preamble, but if Iam doing something amiss in my set up, please advise me so that I can correct the error of my ways.

Now to my intial impressions.
After only a couple hours of listening,it's easy to hear the increased amount of detail.
The issue of volume seems to vary from cd to cd , something I hadn't noticed when I listened to cd prior to the LSPA.
I tend to listen at more modest levels,so the volume control is the lower side of 9, but this is not a problem, I'll take added detail retrieval as the trade-off.

There seems to be some extra lower bass punch on some cd's that I didn't notice before, and on some other cd's I felt there wasn't as much.
That's strange.

My intial take is that the Lightspeeed doesn't homogenize the sound as much as it was before, but not to discredit the Steelhead in any way.It's just that the differences between cds are more noticeable than before, or maybe it's my imagination?

Also, I had two wal warts to experiment, one had variable plugs and voltage settings, the other was fixed.
The fixed walwart was the more robust, the other a bit more edgy, zippy, depending on the cd this could be a mixed blessing.I stuck with the fixed version.

This leads me to speculate on how sensitive the Lightspeed is to what it's power by.
I run it into the digital receptacle of the Hydra 8, but will try one of the analog receptacles.

I too wonder about what battery power would sound like after my initial runs with the two different wall warts.
I've just read George's reccommendation,a bit late as I just sent him my take on the unit before coming to this thread.

Am I happy with the Lightspeed?
Definitely yes,for the money it is great,and the single input isn't a drawback,there's better isolation between sources this way(one reason why I wanted the cd player out of the Steelhead)maybe just a minor inconvenience,as is the lack of remote volume is for others.
Personally I'll take it as it's served up,all the better for the sonics.

I look forward as the hours pass, to judge whether the sound improves , but so far I am very pleased.