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.

Showing 1 response by rob67

I have now had a good listen to my dual mono version of the LSA.
To my ears (and friend's and family's) It has bettered the pre-amps i have had in this system so far, including ARC Ref5se (the Ref 5se was nice with the ARC amps i had previously, (perhaps at a disadvantage due to an impedance issue with ARC & Current SS amp ??). Among other great tube pres, I also compared an older SS Pass X2.5 and Bryston BP20.

George was extremely helpful; not just in confirming impedance compatibility with my current equipment, potential PSU upgrades, but also general audio advice and a friendly approach to my many questions.

My Current system is:
0.25mV MC Cart > Herron VTPH2 phono stage > LSA > Gryphon Antileon Signature > Wilson Sasha.

Herron is configured to lower gain 64dB.

Levels are fine, i am running at 12-2 o'clock, or just past half way for comfortable to strong levels. Although my room is not large, there is still plenty of gain available (not from the LSA of course).

I wont go into its sound too much other than to say it seems to have no sound, very neutral and balanced. When i placed other preamps back in to compare it became apparent what colourations those other pres contributed to the sound, some aspects of which were enjoyable of course but ultimately there was too much trade off. I prefer the clean, open, neutral, balanced sound I am getting with the LSA.

Perhaps eventually I will discover a Pre that betters the LSA in my current system, (I'm sure when i do it will be in excess of 20x the price) or i may change a component and find it an impedance mismatch with LSA. However at this stage, with my current setup it is very impressive and very good value sonically. 

Thank you George