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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
 
Clio09, Tony hi, wonder if you can confirm something for me. As I think you have purchased both stereo and dual mono Lightspeeds from memory, as I have never had the opportunity to do it and it goes against all logical reasoning.
I have had a few report from customers that have the dual mono (left & right volume led brightness controls) Lightspeed Attenuators that they have done comparisons with friends that have the single stereo control Lightspeeds and they believe that the dual mono sounds a little bit better, this goes against all logic for me as the only difference is that the dual stereo pot is split into two mono pots all values and circuits are the same and as all probably know they only control the led brightness and have nothing to do with the ldr signal component.

Cheers George
clio09
3,360 posts
 
Hi George, no I have two dual mono versions. The other one you sold to my friend here locally is also dual mono. So unfortunately I cannot make a comparison, unless of course Pubul57 wants to lend me his for a bit, that is if he can live without it in his system:)

I can't imagine why one would sound better than the other. As you stated the switches are out of the signal path. Maybe the ability to dial in the right and left channel volume separately improves the listening experience, from my perspective this is why I prefer dual mono and it does contribute to my enjoyment of the music. However, I could not see this improving the sonic characteristics or tonal quality of the sound itself.
pubul57 OP
3,712 posts
 
Since rooms and ears (especially as we get older) are inbalanced in many cases, getting left and right just right might help lock in an image - which you did not even know was off till you heard adjusted. Then there is the priciple that we often hear our expectations and it takes quite a while to get past them and to listen through them.
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banquo363
371 posts
 
My asymmetric room is causing, I think, balance issues. I wish I had bought the dual mono version.
georgehifi's avatar
georgehifi
10,312 posts
 
Yes rooms can be a problem, I have a very symmetrical room but about 1/3 along the side wall is a 1 x .7 mt glass fronted photo and it has to have a towel put over it when I do serious listening as the sonic hf mf side reflections it produces does tend to shift the imaging around a little, maybe this is what the customers who are in favour of the dual mono Lightspeed Attenuators model are hearing when they say they like it better.
Cheers George
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