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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
dgarretson
2,601 posts
 
I have not heard LSA but have used the same LDR resistors to provide variable cartridge loading in a modified phono stage. LDRs are about as clean sounding as the best nude Vishay, Caddock, and tant resistors, so I imagine they would make a first class passive.

Regarding the allegation of "forwardness," assuming that we are not talking about strident aggressiveness, the quality of forwardness in a top component is often a good thing in the sense that the piece sounds more alive, faster, dynamic and resolving. The listener is literally closer to the music, in fact the stage may extend both forward of and to the rear of the speakers. In this scenario depth-of-field cues are delivered through high resolution. Instruments appear layered in depth more by virtue of low-level cues than by soundstaging per se. The more astonishing hat trick may be when a system throws instruments outside the L & R speaker boundaries, or does a perfect job of imaging intentionally-recorded phase anomalies to the side of or behind the listener. Some of this is contingent upon room characteristics, but with great electronics it can be surprising how much of it can be pulled off independent of room.
pubul57 OP
3,712 posts
 
Interesting article by Robert Harley in the 2011 Buyer's Guide (TAS) on audio vocabulary - including "fowardness" and "laid back".

What I find with the LSA is that soundstage and imaging changes with the recordings - that to me is a good sign.

One thing for sure, there is simply no arguing preferences, unless you really want to start a winless argument.

What is not arguable in my view is that the LSA provides a very high level of sound quality at a very low price point (for the hobby).

Glad to see that some folks are giving the LSA a try.
grannyring's avatar
grannyring
6,519 posts
 
Perhaps the 2D forwardness speaks more to my system synergy then to anything else. This may well be the case as I have no way of really knowing.

Tvad's point is understood. I guess I always felt the point of a good stereo system was to recreate the sound of music as faithfully as possible to the source - human voice or instrument. I am suggesting a preamp/attenuator is indeed part of the path from recording to ears and always plays a role regardless of being active or passive. Since it will always play a role and has impact on a stereo's ultimate sound, then it's always a means to an end in a total system. The end is, for me, Van Morrison's voice sounding like Van Morrison, a piano sounding like a piano etc...
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georgehifi's avatar
georgehifi
10,312 posts
 
10-09-10: Grannyring
Quote>Perhaps the 2D forwardness speaks more to my system synergy then to anything else. This may well be the case as I have no way of really knowing.

What you should do Grannyring to see if the Dude is artificially giving depth, is what I preach all along, put your CDP straight into your poweramp (Bolero Test) no preamp. Put on a quite cd so you can then ascertain a good level of cd to play, then swap in the Lightspeed then your Dude and see which is closer to no preamp. The one that is, is the one that is truer to the source.

BTW the English and some Aussie speaker manufacturers back in the 70's & 80's use to purposely -3db the level of midrange units to give the illusion of greater 3D depth.

Cheers George
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