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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
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almarg
9,670 posts
 
George, thanks for providing that background.

Paul, I've always interpreted the phrase "controlling the interconnect cables" to mean simply minimizing or eliminating their effects.

As you know, Ralph has made the point that in the case of a balanced cable driven by a balanced output circuit having very low output impedance, that is capable of driving 600 ohms without issues, and with a 600 ohm termination applied at the destination end, cable effects and cable differences will be completely eliminated.

I see no reason to doubt that, and I too have great respect for Ralph's opinions. But obviously most available equipment is not designed to those standards, which is one reason among a great many why assembling a system inevitably involves compromises and tradeoffs. The bottom line on those compromises and tradeoffs, though, seems to simply be the common sense notion that there are many paths that can lead to excellent results, including both passives and actives.

All technically explainable cable effects that I can envision are either directly proportional to or highly correlated with length, so I would not consider controlling the effects of a 1 meter or shorter cable to be a major factor in those tradeoffs.

IMO.

Best regards,
-- Al
pubul57 OP
3,712 posts
 
Thank you. I do love my Atma. Pre/Amp combo too, nice to use a $20 balanced IC and get SOTA performance.
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georgehifi
10,312 posts
 
I ask one thing, for a single ended, low capacitance interconnect of 1-1.5mt, what are we trying to control in electronic and mathematical terms, when phrase "controlling the ICs" is used?

Cheers George
clio09
3,355 posts
 
Stereophile had a booth at RMAF and I picked up a copy of the November issue because my digital source, the Resolution Audio Cantata (disclaimer: I'm a Resolution Audio dealer), made the cover and was being reviewed. Low and behold though, Sam's Corner had a nice piece on active versus passive preamps and some comparisons between a few of them including a new player from Japan). One quote stood out and was even spotlighted: "The best purely passive attenuator I've come across is the George Hi-Fi Lightspeed."

Guess Sam still has a soft spot in his heart for the LSA. Although he is flirting with the new Conrad-Johnson active linestage.
pubul57 OP
3,712 posts
 
But he repeats the myth regarding dynamics, which seem very dependent on system matching across the board, then again, what do you write about when you have found the "best preamp ever"? :)
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