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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
 
The LSA is not available in balanced configuration. George has stated several times that in his testing a balanced design was not reliable. As Photonman advised just get an RCA to XLR cable, but keep it short, 1.5m at the most and ensure the cable has low capacitance.

FWIW I have a Warpspeed optocoupler passive preamp that uses LDR technology. It is balanced but is a more complex design than the LSA. In comparison I found both to provide satisfying results, but overall felt the LSA was smoother and cleaner.
georgehifi's avatar
georgehifi
10,312 posts
 
I have tried very very hard to make a Lightspeed MkII balanced and reliable to stay in calibration even with electronic genius's trying to help out, but without some extra electronics (like sampling impedance values sort of feedback) it does have a negative effect on the sound quality, so it is not possible, and it would of put the price through the roof.
My old MkI Lightspeed design is possible to make balanced though, but it does not sound as good as the MkII. So your damed if you do and damed if you don't.

Cheers George
photonman
96 posts
 
Not really damned. If you try to satisfy every condition, you will be in an endless loop of frustration. You have to take what works and just keep improving upon it, if possible.

Many times marketing dictates product but it sounds like you do not have those pressures. The Georgelofi R and D dept is untethered and answers to nobody but you!
georgehifi's avatar
georgehifi
10,312 posts
 
What I meant is that I would not sacrifice sound quality by going back to the MkI Lightspeed configuration and having to charge more for it because it's balanced. I don't think anyone would expect that, let alone purchase it.
Single ended sounds better if the interconects are kept at a reasonable lenght because of less electronics in the output of the source and input of the amps. If say 10mts or more interconnect is needed then balanced can start to sound better, but the Lightspeed is passive and it cannot drive over 10mts anyway. So we're back to square one again.

Cheers George
audiolabyrinth's avatar
audiolabyrinth
4,555 posts
 
@ Georgelofi, Hi, This is a nice supprise!, You are the owner and Designer of the lightspeed Attenuator?, Clio09 was talking about interconnects low capacitance,, I have the Taralabs zero Gold Interconnect,To my knowledge, This cable has one of the lowest capacitance rattings in the industry!, please look at the specification sheet thats available on the Taralabs internet site, then, If you would, please give me your opinion,this interconnect cost so much money, the only option I can think of to be able to use the Lightspeed mk2 is to buy gold plated xlr to rca adapters!,reterminating this i/c is not feasable!, It would cost more to do that than the entire lightspeed mk2 cost???, my interconnect is one meter long too!, by useing xlr to rca adapters,I suppose I would loose a little performance of the cable, maybe 10%???., Is this unit you have here solid state?,and where does the soundstage set?,a few feet in front of the speakers, in between the speakers, or front and center a roll on the soundstage,what roll of seating would you describe the soundstage to be at, a,d,g???,Is the unit warm sounding,analitical on the treble,big sounding soundstage, small soundstage???,you get the picture, I would like you to be honest and describe the sound attributes of the lightspeed mk2.,I have been thru 3 digital players in 14 months, only one player sounded fantastic!, but the unit was bleading d/c from the tubes into my Krell 700cx amp, and that caused it to shutdown to standby, I had to get a refund on that new player, and the second one sounded like crap period!, I sold that one, then the third one that I do still have sounds fairly good, but the soundstage is to forward for my liking running direct to amp!,I may can resonance tune the forward sound out of it??,I have not obtained the cones of my choice yet that will actually work for tunning.,The digital unit I have uses 6h30 tubes that I really do not like!,The 12ax7 tubes have a better sound stage to me, that was in my first digital player that bleed d/c, I hated to part with the unit,I had too!,, Thankyou!,All of you chime in if you would,Thankyou to all you gentleman here, you guys are very considerate here!, cheers!
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