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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
atmasphere's avatar
atmasphere
11,793 posts
 
Yup.

If you are running a passive volume control, it does not matter how neutral the control is (and the Lightspeed is one of the more neutral ones we have seen), the problem is the interaction of the cables, the source impedance and the input impedance of the amplifier interacting with the resistance of the volume control setting.

That's a lot of variables, and what you can draw from it is that the higher the volume setting on the passive, the more the source impedance is what determines the sound. At full volume you get the least interaction- its the source impedance vs the cables at that point.

IOW, as you reduce the volume, **no matter how good the passive is**, you will loose bass and impact. This is why a buffer between the volume control and the interconnect cable is so important; as you reduce the volume setting the bass and impact is not affected.
teajay
1,691 posts
 
First, for fun:

Saint George continues his holy mission to slay the dragon of active linestages that spit forward the devilish sounds of "colourations/distortions" towards us poor audiophiles who have not seen the holy grail of sonic purity and truth!

I have finally seen the "light" of Saint George's gospel, thank God , therefore will burn my active linestage to cast out the devil's of "colourations/distortions" out of my home forever. Thank you Saint George for saving my sonic soul!

Now a serious question for my friend Paul:

If your goal is to have a volume control that adds or subtracts nothing to the signal passing through it, what Saint George refers to as "colourations/distortions, why do you use before and after the Light speed Attenuator in your system some of the most euphonic/colored IC's and speaker wires in high end audio, instead of very neutral/transparent wires just to pass on this "pure" signal?

I'll give my opinion, even Bobby recommends Cardas for his Merlin speakers because they are just a touch "lean" sounding, so to give them a touch of the body of the harmonic or so to speak a little meat on their sonic bones the Cardas adds that to the mix. Wow, you mean a tone control or adding some kind of colouration to the sound, the highest order BLASPHEMY, according the the holy gospel of Saint George. It's personal taste and system synergy, this fiction that there is an objective standard to what music really sounds like is so silly.

I will stick to one of my original assumptions regarding George's position, any volume controls that are not his Lightspeed are for shit, along with being "dinosaurs" and that his veiwpoint is the only valid one on the topic. I still think he uses this thread to try to sell his piece. Can't wait for Saint George's apostle the honorable Fiddler's attack on me for sharing my opinion. It should be fun what he says about me now.

baranyi's avatar
baranyi
719 posts
 
Teajay and the rest of this thread have made me do some soul searching regarding my audio system. I am going off the grid and there will be no more electronic colorations for me! I am buying a Victrola. This should "Wind Up" this thread ~!
pubul57 OP
3,712 posts
 
"It's personal taste and system synergy, this fiction that there is an objective standard to what music really sounds like is so silly." That is true and I'm not sure anyone, or even George, has spoken about what music really sounds like, his claim is that the LSA will permit the signal to go from the source to the amp with minimal distortion, whihc seems to be a measurable claim beyond subjectivity, which is a different statement, he is not making claims about musicality or what you will like, it seems like a more objective statment that the signal will be less adulterated, unless you have impedance matching issues which will be a distotion of its own, as Ralph points out.

I am somewhat agnostic about the issue of neutrality versus color, I just want my system to sound good and I find the $450 LSA sounds as good with my Music Reference amps as with the much more expensive and complex linestages I have used; that is why I think others should try it if they have a sensitive and high-input impedance tube amp with short ICS, they can get great sound for little money. And, I continue to use my Atma pre with Atma amp because nothing has sounded better with my Merlins and the warm Cardas cables - a great match for an VSM owner.
pubul57 OP
3,712 posts
 
Ralph, why have gain with a CD player with 2v or more output? Any reason? You make a good argument for why you might need a buffered linestage (though Roger Modjeski still advised me to avoid a buffered stage in my setup with his amp - he was perfectly willing to build me one if I insisted), but gain? What for?
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