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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
 
I would though argue that a neutral preamp can be mixed with the widest range of sources and amps, which are then left to present their own sonic signatures.

That's exactly why I'll only have tubes in the amp and nowhere else in the chain. Too many tubes, too much coloration/artifact (granted other non-tube components such as transistors and op amps can add coloration/artifact, but IMO tubes can be the worst culprits). Not to mention we haven't even discussed cables and as Ralph Karsten so often states, the coloration/artifact added by cables also has to be taken into account. Too bad the Lightspeed couldn't be developed as a balanced version that supported the 600 ohm pro audio standard. Then we could eliminate the cable from the equation as well.
georgehifi's avatar
georgehifi
10,312 posts
 
The 0.25mV 103D into my phono pre+active stepup's 64dB gain yielded 0.4V, that just didn't cut it into either of my amps, especially the 1.5V monoblocks.

Looking at those measuremnts you should have had 2.65v output more than most cdp's.
You either have a fauty phono stage not giving 64db of gain, or the cartridge is faulty and not giving .25mv
Cheers George
darkmoebius
900 posts
 
09-09-10: Clio09
Dynavector 20XL low output version rated 0.25mV. However, mine was going into amps whose sensitivity was rated 1V and 0.7V respectively.
The extra +4dB gain that you have over my phono leads to ~37% more output. That could be the difference between barely acceptable and good performance. But, now you've got me thinking that I may have jumped to a flawed conclusion and I should have played around with more IC's. Sadly, I sold the Graham Slee Era phono & EXP stepup, it's possible I didn't need to.

The upside of this may be that I have no reason not to try the Lightspeed in the near future. Especially at it's price.

maybe I'm mistaking you for someone else...I've been to that pictured location in San Pedro listed on your system page (I think you've moved since then) and bought one of your two Scheu turntables at the time. Having two of those tables, me thinks you're probably not a vinyl newbie, but hey, when it comes to vinyl set-up we all make mistakes.
Ha! Good memory, that's me. I moved out of that house 3 years ago, and have slowly been selling off the system for "the next big thing"(which still hasn't happened). I still have the Cain & Cain speakers and the Scheu w/ 80mm platter, though. I'm in a much, much, smaller apt right now, but want to get a vinyl and really good headphone system going in the next few months to hold me over until I move again.

I guess I should be saying "Full Lightspeed ahead!"
robtn
2 posts
 
Pub- Thank you for referencing some jazz. Yes, good-ol' Cannonball. Years ago, the guys in my band (the instrumentalists, I was the singer) got to sit-in with 'Weather Report' (Jaco was a friend of my bass player), and possibly coolest of all, Benny Goodman, Bobby Rosengarden(drums), and Bucky Pizzarelli(guitar), on what might have been Benny's last performance tour. You should hear some clarinet on vinyl thru a Lightspeed. When I use the Lightspeed for records, all I'm running is a "budget" Cambridge Audio 640P into it, behind a N.O.S Grace F9F mm on a Thorens TD160, and it's incredible. Re: "The Shootout" ... Whatever they were hearing was not the Lightspeed, unless there was a black hole nearby, with it's singularity pulling on, and distorting the light between the LED and the LDR. That might have given the Lightspeed the colorations and artifacts some needed ... in case the rest of the system was perfect, and soundless.
pubul57 OP
3,712 posts
 
Anthony, if I read Ralph right, "Not to mention we haven't even discussed cables and as Ralph Karsten so often states, the coloration/artifact added by cables also has to be taken into account." what he has been saying, and given the fact that he makes and sells activ e tube linestages, I seem to hear him say that the reason for an active is to control the ICs, and that is the basic reason for an active, it's buffering of source-pre-cable-amp. Suggesting a preamp makes for a more universal tool in more systems, but that when the total capacitance is dealt with a passive is about as good as it gets, absent the need or desire for colorations of tone or "space".
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