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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
clio09
3,360 posts
 
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.
georgehifi's avatar
georgehifi
10,312 posts
 
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
pubul57 OP
3,712 posts
 
Anthony, your description of the LSA versus the Audio Consulting, is similar to my impression of the LSA compared the K&K with S&B and BENT w/Slagle AVC - all superb in my system, but the LSA seems to do less, in a good way. I wish I could listen to the Placette Active that I bought from another fellow on this thread, a wonderful piece too and one that really does not require a whole lot of thought about cables or impedances - perhaps more universally great - no idea why I sold it - OCD? probably.
georgehifi's avatar
georgehifi
10,312 posts
 
Paul just looked at your system, that is a Esotar D330 tweeter in your speakers? I fell in love with that tweeter when I listened to a pair of Sonus Faber Extremas, it was the first time I liked the sound as much from a dynamic tweeter as my preference for ESL's for high frequency repoduction.

Cheers George
pubul57 OP
3,712 posts
 
Yes, and probably why I have stuck with Merlins for 9 years, or 187 years in audiophile years:)

Thinking about passives versus actives all these years, it brought me back to the words of the Master (aka, NP) describing his Aleph L line stage (manual) which was passive till the 3:00 position on the volume control...

"Above 3 o’clock, active gain is added to the output signal in 2 decibel increments, for a maximum of 10 dB.

As a result, you suffer the effects of active circuitry only when additional gain is necessary."

Raises the question as to the the "effects" are, and when is gain "necessary".

Clearly sometimes both are necessary and preferable, and sometimes not. For some reason, as I get older I want less to get more, but no less than necessary.
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