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
I just got my dual control Lightspeed.  It has a very wide soundstage, stunning detail and is absolutely quiet.  I am very pleased with it.  Seems to work well with my solid state gear

Associated gear

Emotival CD
Weiss DAC
First Watt B-5 crossover 18dB/ octave at 150 Hz
Newly Rebuilt Threshold 4000 (bass)
DIY Aleph J  (wideband)
Dual Plains Audio Altec in open baffle
Lowther DX 4 

Hi all. I thought i'd share my experience of adding a lightspeed to my system as this thread helped me decide to try one. I was sceptical that it would work because my poweramp has a 33kohm input impedance and my dac has a 1000ohm ouput impedance, so it's on the limit of what is recommended as suitable for use with a lightspeed. I had had my dac running directly into the poweramp and controled volume with either software (Audirvana) or a squeezebox touch, but it rarely sounded real. So i investiagted preamps and attenuators and settled on the lightspeed due to it's low price, simplicity and high praise.

Well, the lightspeed has been a revalation. Music has come alive. Without the lightspeed music is compressed, less dimensional and digital. With the lightspeed music is more coherent, instruments and voices have precise space, height and depth, the image is rock solid, there's more detail, deeper tighter bass, and more pleasing tone. I hear nuances that i couldn't with my previous setup. Music flows naturally and consequently i'm more engaged. It's a keeper for sure. Cheers!

First I’d like to thank Dave and Greig very much for their positive findings and review on how the Lightspeed Attenuator sounds in their systems, both of you are using the standard (linear Wall wart) power adaptor. I would like to hear from you what you think when it’s battery powered.

I’ve been recommending a nice cheap alternative in the way of 12vdc Lithium Ion rechargeable, some users have said even better sound with it, even Sam Tellig of Stereophile reported better sound with his Lightspeed Attenuator, and same went for his son. 

These are the ones needed, as you can see quite cheap, the 6800mmA one lasts for at least 24hrs before a recharge is needed. Just make sure with the seller that the plug is 2.1mm and centre is positive.

http://www.ebay.com/sch/i.html?_odkw=12v+rechargable+Li-Ion&_osacat=0&_from=R40&_trksid=p2045573.m570.l1311.R1.TR1.TRC0.A0.H0.X12v+rechargeable+Li-Ion.TRS0&_nkw=12v+rechargeable+li-ion+battery&_sacat=0

Cheers George

Hi Georgelofi, is it possible to use a light speed attenuator on a phono pre-amp?, I like being different and the first world wide to have such a scheme,  if not,  can you build me such an attenuator? 
audiolabyrinth

Hi Georgelofi, is it possible to use a light speed attenuator on a phono pre-amp?, I like being different and the first world wide to have such a scheme,  if not,  can you build me such an attenuator?
Yes it is, I have numerous owners that use it with their phono stages, which say they have never heard their LP's sound so good.
First what is the phono stage you are using as there are the odd ones that are not compatible?

Cheers George