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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
agear
1,362 posts
 
Very well said Teajay. Thanks to Paul/Pubul for stimulating people. He has an interesting perspective as someone who owns both the LSA and an active tubed pre-amp due to system requirements. That dialectic would bother me at the end of the day, but he seems to straddle the divide admirably.

George made some interesting statements about tubes and tube distortion. I love Jazz, and a lot of my favorite recordings were done in the 50s. If I am not mistaken, that means tubed mics, tubed microphone pre-amps, and tubed consoles, etc. Paul Weitzel has done a lot of recording for Sony, FIM, Fidelis and others. He produced some of the first SACD offerings and is a Grammy voter. Paul still uses tubed mics with their own regulated power supplies, tubed microphone pre-amps through a Neve console (which is known for having a warm midrange and uber gain). His recordings are some of the best I have heard. Distortion is not the first word that comes to mind.

While playing with the lightspeed and a direct drive scenario (source driving amps), I did appreciate the apparent clarity and speed. On the other hand, I noted compression of the sound stage, particularly depth, that all important third dimension. If that depth is a tube or gain-based artifact, I like it. It mimics the real thing which should be our frame of reference.
pubul57 OP
3,712 posts
 
Well, tubes definitely do "something" I like, my amps are loaded with them and even the great First Watt and XA.5 designs by Nelson Pass were not enough to convince me to keep them and replace any of my amps, though I very much wanted to get rid of the maintenance issues with tubes, but at the end of the day, for whatever reason, I prefer tube amps - distortion or not. In fact, I'm not sure I would be so keen on the LSA if used with an SS amp as I would hear the amp more clearly, and I think an SS amp needs a tube line stage to sound the way I would like it. I have been focusing on the sound stage through the LSA, as Terry did write to me about the listening sessions he refers to any he reported the same issue with the group feeling the LSA was missing some of the sound staging capabilities of the actives. No way am I going to question that is what the group heard, these are seasoned and unbiased folks as far as I know. After Terry's note I really looked for that up against the Joule which is particularly well regarded for its sound staging abilities and I honestly did not find that flattening, but that was on my systems with my amps and might not be so with other systems. Why you really have to audition and decide for yourself if it works for you - as you would with any piece of equipment and with a few grains of salt in concluding about any piece of equipment simply based on the honest opinions of others.
teajay
1,715 posts
 
Hi Paul, thanks for your kind words towards me. As to be expected from you, words of wisdom:

1) Everybody finally has to audition for themselves to really know what works for them.

2) That unless you use tube power amps the Lightspeed might lack depth in the soundstage and what I call image density or air around individual players. Also tubes still offer, regardless were you have them in the chain, more natural timbres and the the body of the harmonic then SS or passives in my opinion. When I heard the Lightspeed it was with SS amps not tube amps. That's why I believe Paul gets such great performance out of this passive because he does use tube based amps. For me in my system I like SS amps with a tube based linestage to get what I'm looking for sonicly.

To respond to another great GON gentleman, Clio09, who was nice enough to even offer sending me his Lightspeed for me to audition and we have had nice chats regarding his experience with Concert Fidelity gear and his personal relationship with Mr.Tsuda. I'm not attacking George or his product. If you find it appealing to what you refer to in George's attitude as, "a bit cocky", I personally don't like arrogance in any form by anybody. You know George personally I don't, I still think he comes across not as a designer/builder with great confidence or pride over his product as he should, but somewhat condescending towards other viewpoints other then his own.Was your own example regarding that Nelson Pass on a DIY board posted a different version of the LDR proves that George ranks with some of the great designers of the audio world? My take on this is Nelson Pass is open minded about experimenting with different designs, gives credit when credit is do, and is the antithesis of cocky or arrogance. Enough said.

Clio09,when I used the term that George was forcing his product on this thread this was refering to how he comes across to me as being somewhat of a salesman, with the position that his take on what a linestage should offer is the only objective/correct one and this thread was turning into great unpaid advertisement for his piece. Finally, I don't care what happens on AA, my comment was regarding that I have no historical awareness that Ralph or any other well known designer has ever pushed as hard to sell his product as George has, if you can remember someone please share.
pubul57 OP
3,712 posts
 
I think we can all agree in that in many ways Nelson Pass is one of the greatest designers on the planet. I always wonder what he might have done if he applied his efforts towards tube amplifiers, but at he said in his manuals, there were already a lot of great tube amplifiers and making a great sounding SS amp was a bigger challenge for him, he obviously succeeded!! I also suspect that if I had different speakers, I would have kept his XA30.5, the best SS amp I have heard, but my speakers are really designed for tube amps and damping is not a particular advantage for them. Why you can really judge a system, but much harder a piece on its own, and why there never will be can never can by a "best" in any product category, and why a good dealer or a good cadre of fellow audiophiles are so helpful in building a satisfying system. And Terry, your room doesn't hurt:)
knghifi
1,668 posts
 
Pubul57, you a good guy. Thanks for having a good sense of humor :-)
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