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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
Post removed 
georgehifi's avatar
georgehifi
4,966 posts
 
Thanks for bumping Glory, no not dead just resting.

I’ve been on an extended holiday from any production runs, as they can be very taxing/monotonous to produce, just quad matching all the led/ldr’s can do ones head in, as to keep this kind of pricing I run basically a one man show.

Got a few orders and half way through finishing off the next batch to go out.

You should maybe get some more happy owners posting their thoughts if they are members of Audiogon and frequent these pages after they’ve had a good listen, but then most of the next batch is going to Europe and Asia, I don’t know how wide spread Audiogon forums go outside of the US. They seem to have their own go to forums in these areas.

Cheers George
simao's avatar
simao
656 posts
 
Please forgive a perhaps ignorant question, but would substituting a Lightspeed for my existing Jolida Tube DAC and using my Rotel 1072's existing B-B DAC to send a signal through the Lightspeed into my LSA Statement integrayed be a good idea? 
georgehifi's avatar
georgehifi
4,966 posts
 
Hi simao, yes you can.

Seeing the LSA Statement Intergrated has a "main in" this is the input you would use to put the Lightspeed's output into. What you are doing is bypassing all the Statement’s preamp section and using it just as a poweramp.

Then you could use either dac you have to the input of the Lightspeed and use which sounds best with the Statement as a poweramp.

Cheers George
mward
66 posts
 
I’ve been using the Lightspeed for several months now. I purchased the dual volume control version to solve a balance problem in my room. It works great and is as transparent as advertised. I compared it to 2 other passive pre amps that I own, a Schiit Sys and a Tisbury passive. Swapping the 3 passives in and out, and running the source straight into the amp revealed that the 2 other pre’s altered the original sound ever so slightly. The Lightspeed sounds the same as the source going straight in. I still like the other 2 passives, but the Lightspeed won the transparency test. My Lightspeed is feeding a 47 kohm input impedance, no problems there. I really like the flexibility the dual volume controls give me, and the performance has lived up to what I have read about it.

I’ve tried the iFi 12v power supply and a cheaper Jameco linear 12v supply. The difference wasn’t very noticeable in my system, but mileage may vary. I doubt I could tell them apart in a blind test.
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