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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
georgehifi's avatar
georgehifi
4,966 posts
 
Hi B_limo (Bruce) , thanks for the very concise and accurate review of your new Lightspeed.
As for interconnects with it, it is always good to use good quality low capacitance ones from the output to the poweramp, as is the same for tube preamps, <100pf (picofarad capacitance) per foot is fine.(which most hi-end cables are).
Manufactures should be able to answer this, or have it printed in the specs on the packaging.
The input interconnects from the source can be whatever good ones you have handy and like the sound of.
As for the brand/construction this is more system dependent, I for my system prefer copper, some may like silver, which to me is always a tad brighter.

Cheers George
clio09
2,978 posts
 
TelWire from source to LSA and Mogami from LSA to amp.
georgehifi's avatar
georgehifi
4,966 posts
 
TelWire (pure copper?) Mogami (pure copper?) This is what I use as well (99.99% copper) but different manufactures, no multi fine strands, but a couple (4-6) of good size solids cores per phase, this combo give me power heft and tightness as well as transparency through the mids and highs. And of course low capacitance.
I've tried silver at either or both positions, while initially impressive they quickly sounded too highlighted in the upper ranges, not harsh but highlighted, it was quickly obvious that it was disjointed from bass/mid bass to the mids and highs, in other words it didn't flow.
For speaker cable, for my bass (ACI SV12 IB 4cuft 150hz to 20khz) I use again 4 x solid core per phase 99.99% copper.

Cheers George
georgehifi's avatar
georgehifi
4,966 posts
 
For some reason the last paragraph got edited this is how it should read.
For speaker cable, for my bass ACI SV12 IB 4cuft 25hz to 150hz I use 4 x 1mm solid core silver per phase.
Then for the ML ESL's 150hz to 20khz I use again 4 x 1mm solid core per phase 99.99% copper.

Cheers George
clio09
2,978 posts
 
TelWire is solid core copper, the Mogami stranded copper. I made a set of speaker cables using 1 x copper solid core combined with 1 times silver solid core per run.
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