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
Sorry no, we have done it a few times, but without the electronic type/s of feedback that other single ended Lightspeed clones use, they will not stay in calibration over a long period of time, as the matching of the 8 x led/ldr's for balanced output is exponentially more critical than just quad matching for normal single ended.

We have found with a/b listening tests with numerous audiophiles, that these types of electronic matching feedbacks no matter which ones we designed, were detrimental to the sound quality of just doing the proper quad matching without feedback, even though it takes much time, labour and expense to do.
Forced matching seemed to have thinner bass and more etched highs, with a lack of body to the mids, when compared to the production normal Lighspeed Attenuator.


Cheers George
I have been living with my LSA for a couple of months now. It was bought to help improve the dynamics of my system. It has worked better than I hoped for. Not only have the transients improved greatly but the unexpected gain in fine detail and accuracy of the sound placement is indeed a pleasant surprise.
My system has been built up over a period of 20+ years, with the intention of getting the absolute best sound I can, while avoiding the trap of the law of diminishing returns, which is so common in hi-fi. This approach has resulted in an unconventional setup that sounds far better than the sum of components would suggest. It consists of:- Sony BDP-s580 blue ray---Musical Fidelity M1 DAC----LSA---Elliot Sound Products 4th order active crossover---Rotel RB 930AX for highs, Rotel RB991's for mids and lows---B&W matrix 801 s2's now running full active. All interconnects are standard Monster as is the speaker cabling, which has a double run for the bass to reduce voltage drop on large transients. The speakers sit on custom made lead filled stainless steel stands.
The LSA has been the last link added, with the $500 or so giving far more improvement than the price would suggest.
Hello,

As I confirm with Marqmike, I will give more impression.
I am still using LSA and very happy with LSA. After mod with pure silver wire and pure silver WBT RCA plug, the LSA provides very delicate micro nuance, better contrast of micro and macro dynamics, better transient and articulate bass. The treble is sparkling. The only concern is that you have to make sure that the electricity feed LSA is strong enough when LSA is run by battery power. If yours system sound is weak in dynamics, please check battery power first that it is strong or not. When battery power is weak, it makes your system sound no dynamics.

However now I plan to acquire Coincident Line Statement preamp. Because my system is not loud enough when music recorded with low gain is played. My system need more gain. It is not fault of LSA. Because the sound is not loud enough also when I connect front DAC directly to amp. I will give my review between Coincident Line Statement preamp verus LSA when I got Coincident Line Statement Pre-amp.
Thanks Vyokyong
At times I use a Burson ab 160 with my LSA. It is a buffer that is exceptionally organic sounding. I wanted to say tube like but organic/natural sounding is more correct. They are not made anymore but sometimes available used. Now I may change out my internals. Thanks again