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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
3,355 posts
 
I am talking about honest dialogue here and not about product cheerleading. I would have not posted a thing if the builder did not quickly run to the catch all "bad synergy" comment on Knghifi's Samson amp. According to the amp's spec it is indeed good synergy. I simply want accurate and productive discussion that is open to the facts.

I think you're reaching on this one Bill. George was curious as to what the load was on the Samson. He couldn't find any specs and it's well known that TRL doesn't publish them. So all he had to go on was his experience.

Here is what George actually said:

One question Knghifi the poweramp TRL Samson you used for the comparison, it's a solid state amp and I have looked everywhere for it's input impedance and nowhere can I find it, as the Lightspeed Attenuator likes to see 47kohms or higher for the poweramp it's feeding. If the TRL is lower than this you have still not heard the Lightspeed at it's best, and heaven forbid it may beat out the VAC Signature if it sees an amp with the input at 47kohms or higher.

Where's the cheerleading there? Where is the dishonest dialogue? Again, he indicated what has been said here and elsewhere about LSA requirements. Had the specs been published and he could of seen them I'm going to assume we wouldn't be having this conversation. He would have known right off the bat that the input impedance requirements were met.

I don't see where Knghifi is being attacked (pretty strong word don't you think). As for you being attacked when reporting your findings IIRC correctly there was a lot of confusion in that dialogue regarding the definition of transparency. Yours being different than what others here including myself interpreted as the meaning. We all stated our opinions and preferences. Personally I found it a pretty interesting dialogue and it made me think about how I listen.

This thread has had a pretty decent life. Sure it dies down but it always comes back. I think it's done a good job of opening up some peoples eyes as to what is possible sound wise for such little investment. As Fiddler indicated there is a fair amount of cheer leading in the forums, take for example the Supratek and Audio Horizons threads. Do you happen to recall these?:

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1142509250&openflup&2&4#2

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1016931418&openusid&zzGrannyring&4&5#Grannyring

These are just the first posts I ran across.

I'm surprised there isn't a "Dude best preamp" thread on here. Maybe there should be. If there was I'm sure we'd see our fair share of cheer leading, as well as a lot more controversy than what we've seen here based on past TRL threads I have read and participated in. Heck it probably would get deleted just like the last TRL thread on the digital forum.
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
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