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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
 
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.
pubul57 OP
3,712 posts
 
And I forgot to mention, I think the LSA gives me that.
georgehifi's avatar
georgehifi
10,312 posts
 
Pubul57: Raises the question as to the the "effects" are, and when is gain "necessary". Pubul57:

With today's sources, cdp, dacs, even phono stages, there is clearly no need for added gain in most systems. As what most sources can give out today in volts and current, they can easily overdrive (clip) most of today's amps. So all that's needed is a way to attenuate that source no need to give them more gain with the added colouration of what an extra gain circuit gives, only to reduce it back down again to below what the source originally gave out.

Cheers George
pubul57 OP
3,712 posts
 
George, I think we are in agreement, as Anthony is likely to be, and it might seem Nelson Pass is likely to be in agreement too, and yet we find many(?) audiophiles that still don't see it that way, and I respect their view as well, but I guess I am just comfortable with my own conclusions, theoretically and in actual listening - and whatever divergence of opinion we have seems like an uncrossable bridge, so we are left with try it and see what you think.

But the argument is also between a $500 approach versus 5-20K approaches, so where do you go from there? I don't know. I can only recommend that folks try it and decide for themselves.
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banquo363
371 posts
 
From reading A. Salvatore's review of the Coincident Preamp, I get the idea that it is not trivial to discern whether the source can deliver sufficient current and volts to make an active preamp unnecessary. After all, for more than a decade he believed his source was sufficient but it turned out, by his standards, it was not. I take it then that if his observations are correct (a big 'if'), then one cannot merely look at a spec sheet to determine sufficiency.

The question is, what more is there to look at? One can do the Bolero test, but Salvatore did it and it gave him the wrong answer and misled him for a long time. What then?
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