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
Disciplined testing? I don't know. Just kept switching between preamps with the same 2-3 "test" tracks for a week, over and over, brought audio buddies over to minimize the possibility I might be hallucinating, and I (we) enjoyed the LSA every bit as much as much as my relatively expensive tube linestage and so I decided to save the $7000 and not worry about tube replacement (I have enough of them to worry about). Not science exactly, but enough to make a decision. Hard since the linestage is probably the #1 recommendation by the speaker manufacturer for his speakers and the one he uses at shows, and I certainly loved it - but still....I also have no phono, and no switching requirements.
I would like to test the LSA against the $16,000 Music First Audio Reference Passive. Not sure that is going to happen though. Wonder if it includes an IWC for keeping time.
Paul, I agree with all of that. Speakers and room are easy breezy. I also readily admit the the blinded A/B thing is hardly scientific in my hands as I have no dedicated switching device, etc. Most posturing on my part. lol. It was very "scientific" of you to included friends in your decision. That is good enough for me. I include my wife in all audio decision-making to protect me from me and my strong abilities at self-deception. That being said, it would be an interesting exercise to see if you could discern specific personalities of the passives discussed thus far.

I am not familiar with the music first piece. Does it make espresso as well?
One correction to Agear's very interesting post. The Truth is an active buffer, not a passive.

To answer his question, I am not a betting man but in a blind test between the Truth and LSA I would bet I could pick them out. This is not to say my hearing is that good, it is to say I have spent so much time listening to these two preamps that I know them that well. Each do a couple of things really well that my test tracks would allow me to pick the correct preamp. Now if I were not as familiar with them then all bets are off. I would probably have a difficult time picking them out. It took me quite a while to figure out the nuances of each unit when comparing them.

Pubul57 - I tested the LSA against the Audio Consulting Silver Rock. It was evident that the LSA just got out of the way of the music, like it didn't even exist. In some ways it was a similar experience to something Himiguel wrote in an earlier post here. It was like I could hear the Silver Rock's signature, whatever was causing it to have one. The LSA was obviously the more neutral and truer (purer) preamp.
09-16-11 Agear: George, does Cadmium have a sound? Is that part of the reason why it is perceived as superior to carbon or metal? What specific measurements or measurable parameters separate the LSA from other passives or active pre-amps? :09-16-11: Agear

Ager, It may very well be the most transparent sounding resistive substance, their is no way to measure this.
But I believe the Lightspeed Attenuator to be "the truest to the source" way of controlling the volume because their are no contacts (diode effect) in the signal path, this is why darTZeel has used them in their $24k NHB18ns preamp, also Constellation Audio with their $60k Altair preamp uses them as well.
All I can say Ager is with the Lightspeed Attenuator you get the closest to the sound of having your source directly connected to the poweramps, yet with control over the volume, it adds nothing and takes away nothing when implemented properly, it is "true to the source"

Cheers George