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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
 
Let's just leave it at this. The LSA is pretty good, and "not bad" for the money. Give it a try and decide for yourself if it competes with the $$$$ gear, I think you might find the test interesting and well worth keeping even if you decide it does not better your $$$$ linestage, or, some of you just might sell your $$$$ linestage and spend the money elsewhere, including, possibly, more music:)

Everyone, have a great New Year, I hope is 2011 is better for all of you.
knghifi
1,668 posts
 
I just report what I (and several audiophile friends) hear and didn't felt I was attacked. But I do understand Grannyring point in Georges questioning of the Samson input impedance, which can be construded negatively, after it was confirmed by multiple sources it's well above 47kohm and my personal listening experiences eventhough I don't have golden ears.

3 more points:

1. My MW Transporter has the ability to drive amps directly so it has more than enough gain.
2. Liveline IC between LSA and Samson is 1M.
3. TRL Dude has a tube regulated power supply so it makes no sense for the Samson to have an input impedance below 30kohm.
grannyring's avatar
grannyring
6,471 posts
 
Fair enough Clio09. I agree with your thoughts and let’s move on. I and Knghifi were not attacked and I did overstate that a bit. Ya, I did purchase the preamps in the threads you posted. Liked them both. I will always tell the Agon community of gear I find to be awesome as time goes by.

Please understand that one can reasonably take the comments of the Lightspeed builder as implying, if not directly stating, a match/impedance issue was present This is especially true when the owner gave the spec asked for and it was still questioned?

That is the way I read it, but the Lightspeed builder may well be confused on the amp in question and really having trouble understanding how it has the spec confirmed by Knghifi. This is certainly possible.
georgehifi's avatar
georgehifi
10,312 posts
 
OK now here's the truth from the horses mouth, the Lightspeed was seeing a happy load and Grannyrig check your facts before you double swear it was 100k input. And as I said for it to be over 47k it would have to be Fet input. Below is Paul Weitzel email to me. Cheers George

Hi George. Answers to your questions.

1. 68K ohms

2. FET input

3. DC coupled

They have pretty normal specs.

Take care.
Paul
TRL, Inc.
tuberesearchlabs.com
pubul57 OP
3,712 posts
 
So Knghifi heard it under "appropriate" conditions and prefered his excellent VAC, fair enough, and a valid preference. The TRL amps are all SS? Not hybrid?
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