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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
pubul57 OP
3,712 posts
 
"If these things "don't add or subtract", why are they so hard to match? Can't perfection be duplicated?"

They are not that hard to match, you just need a tube amp or a high input impedance SS amp - gain is not much of an issue in most systems. But it is not a universal solution, that is why we have so many expensive linestages that are essentially plug & play into any system, what is lost is the simplicity and purity of a signal that isn't messaged to enable to work in any environment. So you can have a preamp that will work in any system, but compromised by the circuit complexity required for that, or choose a simpler device that will not work in all systems, but because of that simplicity provides a cleaner connection to the recording if not challenged by impedance mismatches. A little more work to get it right, but well worth it if you want to take this approach. I'm sure George would make a universal device that could work in any system if he could, but it just doesn't exist. This is a minimalist approach that can lead to great sound, but it can't work without some thought given to the source, cables, amps, and speakers.
fiddler
581 posts
 
"...purest reflection of the recording..."

Excellent post Pubul57.

When comparing my Supratek to the LSA, I did find the Supratek to be just as transparent without any "usual" tube colorations. I was actually surprised that the Supratek is as neutral as it is being a tube component.

Where I found the LSA to be very slightly better was in the lack of any sibilance. Admittedly, I only heard a very slight amount with the Supratek, but I HATE sibilance. So in the end, the LSA and my Supratek sounded almost identical to my ear. The only area where I thought the Supratek may be slightly superior was in the depth of the soundstage.

In the end, the LSA seems to give me vitually all of the positives of my Supratek without any clearly identifiable sacrifices. The good news is that the Supratek seems as transparent as the excellent LSA passive and the LSA seems to be as bold, dynamic and full-bodied as an outstanding, highly-regarded tube preamp. They both are excellent.
georgehifi's avatar
georgehifi
10,312 posts
 
If the signal/source is poor, yes you can alter, soften,bloat thin out or whatever with an active pre, depending on it's own character of sound, yes a it's band-aid fix as you said.
With the Lightspeed Attenuator you hear what the source/signal is giving, if it's not to your liking, I say fix the problem (get a better source) not bad-aid fix, as when you fix the source/signal or put on better cd's on then the band-aid is still there in the signal path, with the chosen active pre.
Cheers George
knghifi
1,668 posts
 
That's my point, there are no perfect cds (over 80% are compressed. I like the music but recording sucks), source and interconnects. By the time the signal reaches the preamp, it has been altered. So what you are saying is if you like the sound of a passive, you prefer how the source and interconnect altered, amplified, added / subtracted ... tone controlled the signal.

I don't understand the statement if you prefer active, therefore you prefer a tone controlled signal. This is only TRUE if the preamp is the only component in the system. The signal gets altered as it travels through the chain of components. But I do see an advantage of a passive preamp in an integrated amp.

Let's agree to disagree and move on.
clio09
3,355 posts
 
Let's agree to disagree and move on.

Isn't that what we've been doing for the last 8 pages and nearly 400 posts:)

Let's face it, we're relying on the recording engineer to interpret the event and put it down in as accurate a means as possible given their hearing skills and the equipment used to mix the recording (the first introduction of tone controls). I agree with Knghifi that most recordings are awful. So the process is flawed from the start.

To listen to what the recording engineer intended us to hear, we have to rely on a means to reproduce the sound of the recording. What that means is comes down to preference (and what we can afford). One such preference is to use as few components as possible in the signal path to eliminate unwanted artifacts and coloration. It's not a perfect means (we still have other tangibles to address in the process) and it may not give us the sound we prefer. It's just one means and the one I and others here subscribe to.

But I do see an advantage of a passive preamp in an integrated amp.

Ralph Karsten has indicated that the best approach to addressing passive attenuation is to implement it at the amps input. He offers such an upgrade for his amps (M-60 and above). It certainly simplifies the process (one less set of interconnects) and I wish more designers would offer this option.

Maybe George can come up with a module based on the Lightspeed design he can OEM to amp manufacturers;)
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