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
Just to add to my previous post on microphonic tubes, if you hear a bonk in the speaker because of a slightly microphonic tube/s, this in turn when playing music will give and artificial effect of adding ambience/echo to the music, if that your bag so be it.
But I will always be in the camp of what goes in should be exactly what comes out, nothing added nothing subtracted, warts and all.
Cheers George
Seems then all the high end preamps, tube or SS, costing up to $100,000 that are not passive, just can't get it right? Or should I say as right as a passive?
Grannyring

Well, I think there is a lot more to it than meets the eye. Let's just say designers have their preferences just like the audiophiles that buy their equipment. What's "right" for one may not be "right" for another. Also, designing something that makes you stick out like a sore thumb, regardless of the quality is always riskier, and in many cases less profitable. Especially when your peers are following a certain formula and marketing hype (eiher from reviewers, manufacturers, or other "experts") is telling the public what their expectations should be. This is not specific to home audio either.

Now I'm really going to throw one out there. These designers that market uber expensive amps. How would it come across from the consumer perspective if they matched it with an inexpensive little preamp? Bearing in mind that us consumers, regardless of whether it's audio components, cars, etc. have certain expectations for how $$$$$ translates into perceived quality or perhaps more accurately, status. IMO, these designers wouldn't be taken so seriously. In much the same way as if Ferrari came out and said you don't need top of the line Pirelli's on our cars, we're now going to supply generic Acme Brand tires and all will still be the same. Really?

Let's assume my active preamp is more noisy then the LSA. If it outperforms the passive in many other areas, then it may still be a preamp truer to the recording. Benefits outweigh the short comings kind of thing.
Grannyring

Again, there are specific definitions and preferences in play here, but this is precisely the point.

The truer to the recording thing aside, I'll give a personal equipment example. I've been playing around with a Transcendent Sound T-16 OTL. No one could ever confuse this amp with the term "graveyard quiet." First, there is a low noise upgrade option for it. That in and of itself should tell you something. Second, its pretty well documented that the layout of the wiring does cause some noise issues, and its slightly louder in one channel than another (and we're talking just at the speaker, not out into the listening room/position just in case anyone was wondering). The designer took some measures to rectify this as best as possible, but even he will admit the amp is not dead silent and doesn't apologize for it. In the end he replies with a simple question, "So how does it sound?" Indeed it sounds great, the benefits far outshine the shortcomings.

Ralph Karsten designs his amps to be used with an active linestages and while I've used mine with the LSA I will say it sounds better matched up with The Truth preamp I have that uses active buffers, and the Berning Micro ZOTL that is a true active preamp design. The LSA matches up much better with the Music Reference RM-10 and VAC Auricle Musicblocs.
Wow!! Out shopping and dinner and missing all the fun.

For the record,
1. I highly recommend the LSA and I plan to use it in my system ... it's all in my initial report.

2. I never said my stuff is the best. I can only report what I hear in MY system. I always emphasize "MY" system.

3. I never questioned anyone preferences ... whether tube, ss ... is the best and frankly I don't care. I buy and keep what I like.

I was simply asking for an explanation on the statement ... the signal from the source will accomplish what the recording engineer wants you to hear. It makes no sense to me since not aware of a PERFECT source or interconnect.

Pubul57 and Fiddler

Can you boys recommend the source and interconnect with consensus from all the recording engineers that will accomplish what the they want me to hear? I want to take the technology and implement it in all the cables, amplifier, speaker ... and then have a perfect system. We can nationalize if like Obama care, one size ...no, I mean one system fits all. Think of all the $$ and time we will save. Then finally all the "Best" and "King of MONO" threads are no longer dumb.

Pubul57, did you really sold your Lamm, CAT, Ferrari 458, Joule, Porsche 997, Atma-Sphere, VIVA ... for the LSA? Only seen it in 5555 threads so wasn't sure.

Bye Fiddler, Happy New Year.
Yep Clio09 your points on the high end builders are interesting. Your real life example with the Transcendent amp is a great example.

Ok, time to listen to Van the Man with my microphonic tubes:-) Van's voice seemed you ring more when he was younger. He now has a warmer, mumbling tone that is more microphonic tube friendly.

I will try George's tube test soon.
I will try George's tube test soon.
Grannyring

It's not my tube test, it's a well known way of checking for microphonic tubes out in the field among techs without the use of expensive equiptment. You can aslo do the same with tubes in poweramps, not just pre's.

Cheers George