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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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georgehifi's avatar
georgehifi
10,312 posts
 
Let's get this right!!!!
The Ravel's Bolero test is just a level test, that all, as it starts off very quite and builds slowly so you can gauge level when directly connecting CDP to poweramp, so you don't blow up your amp/speakers.
You can use any cd that starts off quietly, not just the Ravel's Bolero cd!!

Cheers George
pubul57 OP
3,712 posts
 
I don't think there is any confusion about why "Bolero" is a recommended piece for trying a direct connection between CDP and amp.

Not sure I've hear an argument yet as to why a direct connection is not "the" standard for assessing the sound of a recording from a particular CDP as a source, to me it seems absolutely is the standard of what a recording sounds like unadulerate and uncolored by the use of a preamplifier; the LSA is about as close to that as you can get, and an active preamp, which one might prefer, in nevertheless an additive coloration not found in the source signal.
grannyring's avatar
grannyring
6,436 posts
 
Got it and understand it perfectly Georgelofi. Did this several times on past systems after reading about on A. Salvatore's site.

Tony (Clio09) - thanks again for letting me play with the LSA. Great fun and I always learn more. You are welcome anytime to my home and music room in Southern Minnesota!

Pubul57 - I also love my Atma-sphere amps!
grannyring's avatar
grannyring
6,436 posts
 
Pubul57 - Seems I have written pages :-) on this yet no understanding of my point? It may be impossible and that's OK!

A "direct connection" as you say, is as I say, just another STEREO SYSTEM and produces a sound of its own. Direct connection from CD player to amp is not, as another has stated here, the GOLD STANDARD, it is simply another way to hear music out of a stereo system. A CD player driving amps is still a stereo system that does or does not reproduce the voice or instrument accurately to the recording or live event. The END result (sound) of a system is the proof. I and others suggest a passive unit "can" or "sometimes" can, depending on the total system, fail to pass along the recording with a sound that is true to the source. This can also be true of an active unit.

Many folks far more educated then me on audio circuits and recording practices will wax poetically why DAC's/CD players etc.. are an insufficient means to pass along the signal to an amp with only a passive in the chain. Meaning the resulting sound may lack in areas as the system simply lacks the horsepower needed to convey the energy and space of live music and great recordings. I don't want to argue that and all the math and audio geek talk that goes with it. I do know what I hear however in my system. It is not added coloration; it is in fact hearing MORE of the recording as intended with my active in place.

One reason may be as simple as my active Dude preamp has all the lows, all the highs, all the transparency, and depth of field and soundstage width simply because it actually amplifies ALL that is there and does not mask as has been implied. Amplifying the low-level stuff, stuff that might not get through (stage depth & other nuances) is important and not insignificant as we know. Is it possible a great active can get more of this information by way of design then a passive? At least as much? Seems reasonable to me.

Just trying for us to see with a broader view that sweeping comments about one type of design being the GOLD STANDARD may be a little narrow?

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