2. amps-preamps
  3. 1276356977

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

Showing 13 responses by photonman

photonman
96 posts
 
Would capacitance be offset by higher source output?

I ask because since I put a chordette qutehd dac into my system, the volume position for normal listening went from 11 to 9 or 10 O'clock.
photonman
96 posts
 
This forum is dangerous.

I just ordered one as I always wondered about removing the preamp but never acted on the thought until this forum and at this sane and reasonable price, it is a good calculated risk to take. Really curious about this one.
photonman
96 posts
 
If no balanced LSA is possible, you can easily get a cable made with XLR/RCA terminations but you will not be balanced anymore but so what :)
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!
photonman
96 posts
 
what kind of case is the LSA built with as it looks like some type of casting in the pictures and not the usual bent sheet metal?
photonman
96 posts
 
Just received mine and have been listening for two nights now and loving every minute of it.

This little box really makes me think that I will never again need to spend bank on a pre, and as such my $3k Bryston is now sitting under my bed collecting dust and soon to be on the for sale block.

Worst case scenario, the Bryston has nothing sonically over the LSA except source switching, which I do not need. The LSA is much more transparent in my system as I am hearing instruments and voices that I never knew existed in some passages, very revealing and detailed.

But the first thing I did after hooking up the LSA, was to turn on my system and with no source playing I put my ear to my tweeters and with a big smile on my face, I heard absolutely NOTHING, no "ocean" white noise that I heard with my Bryston with volume at zero position.
I am guessing that is a good thing but I am only an amateur at this audiophile stuff.

I hate to speak in cliches, but I am really enjoying rediscovering my cd collection. But Of course, each particular recording has a different effect from the LSA. Particularly, live and unplugged music sounds more live and bad recordings sound more bad, a side effect. So your source component is now in the spotlight as to the quality of the signal reaching the amp. Now I am rethinking whether I should upgrade my source, cdp or go digital. Isn't it ironic says Alanis.

I am using a 3 ft set of Bryston IC's (Canare and Neutrik) which are 21 pf/ft into the LSA and a 2 ft set of Blue Jean IC's which are 13 pf/ft out of the LSA to amp.

Another nice side effect, I have one less 17" component box and its outboard power supply, less cables and wires and my rack actually looks organized and clean.

So to summarize, a great sonic value and a truly novel product from a pretty cool guy to do business with from 7.5K miles away.

I am very happy with this purchase and by far my best and most dramatic change to my system.
photonman
96 posts
 
I have the Blue Jean LC-1 which is 12.2 pf/ft.

$31 for pair of 3 footers or $29 for 2 footers.

The Brystons I already had otherwise I would have used all Blue Jeans.
photonman
96 posts
 
I have had my LSA for two weeks now and I have to say this is one of my best hifi purchases in all respects.

Definite sonic value. It is just as transparent as my previous more expensive active pre but with less noise so my active is currently for sale.

This device has changed my attitude toward equipment purchases and shows that a little experimentation can yield pleasant surprises.

The LSA is the stripped down race car or race sail boat of stereo equipment.

A great novel product and worth an audition in any system.
photonman
96 posts
 
Hi Seshkir,

Really, a battery supply? How does that work as I thought the power was only for the LED things? Does the light intensity or whatever change characteristics with the battery?

What is your battery rig consist of? Is it DIY project?

Thanks
photonman
96 posts
 
cable question: should the cable pair with the lower capacitance go between the LSA and Amp or the Source and LSA or does it not matter?

I just upgraded my cables but the more expensive cables have twice the capacitance as my cheaper Blue Jeans.

Both pairs are 2 feet.

Thanks...
photonman
96 posts
 
Cool, Thanks George,

My new 2 foot cables (Blackcat Lectraline) are 37 pf/ft so a negligible change
photonman
96 posts
 
UPDATE: New Amplifier in my rig

So on a whim, I decided to try out the Nelson Pass First Watt J2 amplifier at 25 wpc. I was concerned about the volume levels but no problem watt so ever with the J2. Actually, the LSA works smoother than with my Bryston 4b SST amp. It is a great combination and I could not be happier.

Th J2 itself is such a nice amp, so smooth yet detailed and 3D imaging and the sound at low volumes is so much better than with the Bryston.
photonman
96 posts
 
Hello again George, still loving m LSA and I did add a TeraDak PS to the mix.

At first I thought I heard a big difference vs. the wallwart but now I am used to it but I am staying with the TeraDak. Yes that red led is BRIGHT and be carefaul as the face plates are sharp. I hid my unit under my bed and my wife stepped on it and sliced up her toes very bad...

Curious how this Nelson Pass unit compares to the LSA...here is a link to some circuit diagrams:

http://www.firstwatt.com/pdf/prod_b1_man.pdf
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