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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
10,312 posts
 
Here is another reasonably priced linear powersupply, you Lightspeed owners may wish to play with, with digital readout!!
It has the correct size output plug, at 2.1mm X5.5mm with center positive.

All you have to do is specify 220v or 110v mains and say you want the output set for either 9vdc or 12vdc. Both voltages work, as I have a second regulated supply inside the Lightspeed which re-regulates again.

http://www.ebay.com/itm/Hifi-linear-power-DC-1-USB-amp-DAC-external-power-supply-with-digital-display-SN-/221458260575?pt=US_Home_Audio_Amplifiers_Preamps&hash=item338ff0e25f

Cheers George

richarddunn
1 posts
 
This only applies to UK and European Union members.

There seems to be complete ignorance about these Light Dependent Resistor products. A word of warning really needs to be published about LDR based pre-amps. LDRs contain Cadmium gas which is lethal (kidney or liver failure) if eaten or breathed and is a long term serious health (Cancer) risk if just touched on a regular basis. Because of this it is illegal to import or sell these items within the EU as they are not RoHS or WEEE approved, so cannot be given a CE mark. This is true for both kits and built products.
georgehifi's avatar
georgehifi
10,312 posts
 
So is the Beryllium(Be) used in Focals/JM Labs and other speaker manufacturers that use Focals top tweeters.
So is Yamaha NS1000, NS1000X and NS2000, tweeters and midrange units.

So is NOS and OS tubes that have Nickle(Ni) inside them.

And so is the lead(Pb) based solder hiend manufactures still perfer to use.

I can go on and on, at least the Silonex LED/LDR package that the Lightspeed Attenuator uses, are hermetically sealed within a tough hard acid resistant plastic case, I don't think anyone is about to open up a Lightspeed Attenuator put one in their mouth and crunch down on it like a boiled lolly. It's not "Cadmium Gas" it's Cadmium Suplhide (CDs) solid.

http://en.wikipedia.org/wiki/Photoresistor

http://en.wikipedia.org/wiki/Cadmium_sulfide

Cheers George
erwann
6 posts
 
This is vintage EU mind control: identify genuine existential problems, say the girth of bananas, to justify a metastatic bureaucracy, whose days, judging by the latest EU Parliament elections, are numbered.
erwann
6 posts
 
Graham Slee's 2006 interview with TNT (http://www.tnt-audio.com/edcorner/july06.html) offers an eye-opening overview of the stark implications of RoHS for small to medium businesses, best summed up by his assessment that "all this legislation has a soul destroying effect on the designer who tries so incredibly hard to share his/her talents with the music lover, only to be shunned by what would seem to be ruthless dictators." Amen!!!
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