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
Post removed 
Ah! A good music recommendation, I will get that.

I never compared the Atma-sphere preamp with the LSA as I use it with the Atma amps in all balanced connection, so I jave not been able to compare them with the same amp.

I use the LSA with the Music Reference RM10 (summer) and RM 9 Special Edition (Fall), both amps single-ended. I went through a series of preamps, most recently the CAT SL1 Ultimate, Lamm LL2, and Joule LA150 Signature Edition. Of these, the Joule was the one I liked most and could live with it forever, but I decided to try the LSA just to see what it might do versus one of the best sounding active tube linestages I have owned. I kep going back and forth for a few months, and without too much analysis, I simply felt I liked the LSA better, certainly as much as the $7,000 Joule - seemed silly to keep both with that kind of price differential and since I only have one source, low capacitance cable (Cardas GR), and both MR amps were designed by Roger Modjeski speciofcally to be passive friendly (High input impedance, high sensitvity <1v) I figured that while an active will sound better with a wide range of sources, amps, and speakers, my particular system is really passive optimized and that under those circumstances a passive should be better at passing the signal undamged from source to amp.

The LSA is very, very quiet, seems to be very well balanced from lows to highs, has a very wide and deep sounstage with recordings that have wide and deep sounstages - soundstaging with this preamp really is a reflection of the recording and not a constant attribute, and imgaging and localization is very precise and unwavering, and instruments seem to have their naturural size and instrumental bloom. I also notice that music can be played louder without unpleasant shout that can occur with some systems.

Within my system, there is really a hairsplitting comparison with the CAT, Lamm, and Joule - they are all exceptional pieces of equipment and enjoyed all of them. There is not however a hairsplitting difference in price - which is why I love the LSA, it can give audiophiles without deep pockets SOTA sound if they pick their sources, cables, and amps carefully/properly. Or, if you have the money, you can buy one of these great linestages and have a great system too, without worrying much about system matching.

Arthur Salvatore says that if your system sounds better with an active linestage, your system needs an active linestage - but if you don't need one, a passive is the way to go. I think this in part explains why some folks swear by passives, and others say they much prefer actives; I suspect where you fall depends on your system as a whole, and not necessarily a reflection the inherent qualities of either approach - why as they say wisely, your milage may vary.
This is a great thread. Agear is spot on about the LSA or any passive /active preamp doing something to the sound as signal does flow though unit hardware and such :-)

The LSA was at 75% of full volume in my system to get 90db of sound as an FYI.

George, I don't doubt the LSA will sound very close to the Bolero test. Fact is I think it will. I am saying that this type of sound is not what I am looking for. I just have experienced an active preamp that makes my system sound more like live, natural and beautiful music. This is not possible (at my current level) without any preamp or with the LSA in my current system.The LSA is awesome in so many ways and a steal for the money.

I greatly respect what you have accomplished and know the LSA outperforms many a unit regardless of cost. I do however have an opinion about my experience with it in reference to my prefered active tube preamp. No, I don't think my active unit is adding anything. I really think it is giving me more of what I hear in live music and in my great recordings. Again, in my system as is.

I can't and don't make a blanket statements for all people, systems and rooms :-)

This little LSA is great fun and if my active did not steal my heart I would own one!
Post removed