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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
 
Yes we tried doing the same auto-calibration system in many different configurations all with the same negative results to the quality of the sound.

Documented years ago in diyforum, we tried many auto-calibration circuits for the Lightspeed Attenuator, to try to save a large percentage of production costs, of parts costs and labour cost and of the tedious task of quad matching the led/ldr's.

Active auto-calibration (or to give it a more understandable name) "forced matching" circuits have to be attached to the signal carrying output, there is no way around this.

On all the auto-calibration circuits we tried to save on these costs, we came to the final conclusion that they all interfered with the purity of sound. In that they added a highlighted sound to mid to high frequencies. And in effect seemed to reduce the bass a touch at the same time.

So to cut a long story short we stayed with the purer far more costlier system of quad matching all led/ldr's for the Lightspeed Attenuator and auto-calibration was not considered option no matter how well it was designed.

Cheers George
glory's avatar
glory
1,614 posts
 
So Tortuga is doing the same exact build as you but with a remote and gets $1.2K for their unit?
georgehifi's avatar
georgehifi
10,312 posts
 
3 x the price yes, remote yes, same build no, they use the auto-cal "forced matching" circuit to save on production/labour costs as I outlined in my last post.

Cheers George
bobxsherman
4 posts
 
Well to answer the question, IMO a resounding YES! As a long time user of George's preamp I wanted to just express how happy I am with it. I have owned several active preamps and transformer preamps over the years and by far the Lightspeed is the most transparent I have owned. I have a collection of equipment, but no matter what I try, I go back to the LS. I am currently running a simple system consisting of an upraded MiniMax+ DAC, Lightspeed, Hypex Amps and a pair of super transparent Yamaha NS1000. No preamp conveys the music IMO as the Lightspeed does. :)
gracerev
1 posts
 
I just got the Lightspeed Attenuator. It came quite simply but securely packaged. The design is pleasant and solidly built. Was excited as I've read so much about it in the forums. Wanted to see if all the hype was for real.

After running in for about 4 days, I can honestly say it has lived up to the hype. Through my Esoteric transport/Bricasti DAC, which itself was already very transparent, the Lightspeed made the music flow even more freely - there was more detail, greater sense of ambience. Even at low volumes, the music just flowed. Quite remarkable. The staging is wider than my original set up. Bass was articulate, and voices were very life like. Instrument timber and inner details shone.

Overall, I'm a very satisfied customer. Amazing sound at any price. Yet the price is A$470 which makes it the best value component of my system.
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