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 14 responses by kevinzoe

I've bought George's Lightspeed and am (im)patiently awaiting him to build it and ship it half-way around the world to the frozen Canadian tundra. Build George, build . . . It'll be connected to an Art Audio PX25 SET amp driving 97dB efficient speakers - hope it sounds as good as others claim.
Pubul57 - I used to have an Audio Aero Capitole MKII SE CDplayer with built in preamp connected directly to my amp. I had to sell it to buy a new transmission for the car (ugh!!) so will be using a old Sony CD player with the Lightspeed until funds will allow an Mac Mini computer to act as source that'll be connected to a Pro DAC which will feed the amp.
Hi Guys,
My Lightspeed was delivered today and it looks well made. I've fired it up but it's too early for any critical listening. So far, it sounds very good!
. . . now that that school yard bickering is finished ;) let's get back to the topic of the Lightspeed and its performance . . .

I took posession of my Lightspeed last week and have only about 5hours on it thus far. Last night I was listening to Bobby McFerrin's latest CD which is a spectacular vocal potpori of harmonies, complex arrangements and some rather interesting African tribal chants and rythmns. I got goose bumps listening to it and for the first time those goose bumps migrated down my body to my legs - wow, what a sonic affect and physical sensation.

Now considering that I am using an old Sony 5 disc carosel CD player and that my room treatments were in disaray due to some current reno's I'm doing, I would hazard to guess that these sub-optimal conditions that didn't exist when I used to use my Audio Aero Capitole MKII SE CD/Pre speak volumes to the excellent quality of the Lightspeed.

Of course you could argue that with so many different variables that it's next to impossible to isolate the sonic goose bumps to the Lightspeed alone, and of course you'd be correct. However, I'm pretty sure the Sony's sonic quality isn't as good as the Capitole so what I heard was an improvement, plain and simple.

Congrats George!

Kevin
Fellow Lighspeed owners - The listening level that I use has my Lightspeed volume at about 8-9 o'clock as my 97dB efficient speakers don't require many watts to crank them up (I'm using an Art Audio PX25 SET amp with 6watts/ch. by the way).

Am I missing anything by not having the volume at a higher setting (11-1 o'clock for example)? Besides getting louder, will the sonics improve as I turn the volume up louder?

Thanks!
Clio09 - thanks for taking the time to do your homework before your great answer above. While I intend to purchase the LIO-8 DAC I am currently using an antiquated Sony 5 disk player (CDP-CA7ES) which has an output impedance and voltage of 10K ohms and 2volts respectively.

Knowing these specs now, does it change anything in your answer Clio09 or am I still 'safe' in that I'm not missing anything sonically by having the volume control low at 8-9 o'clock?

Off topic - was the DIY Skyline Diffuser write-of of mine helpful / useful for you?
George - thank you for chiming in. Glad to hear that no sonic purity is being lost at 8-9 o'clock than further around the volume dial.

Clio09 - Hemi-cylindrical (polyfuser) diffusers are much easier and faster to make than Skylines of similar size. Email me if/when you wish to consider tackling them.

Happy listening all.
Hi everyone,

I stumbled across another lightspeed attenuator maker named Uriah Dailey whose product is called "Lighter Note Lightspeed Attenuator." 'Lighter Note' may be his company name - not sure. Here's a link:

http://www.buildanamp.com/main.sc

I don't know how it differs from George's Lightspeed version, but wanted to bring it to light (sorry for the pun) for those considering a lightspeed attenuator.
Pubul57 - Uriah selll kits and finished products as per his website.

anyone tried his Lightspeed product and how it dffers from George's?
Devilboy,
With my 97db efficient speakers - similar to your 96db speakers - I rarely get above 9 o'clock before being too loud. Often depends on the recording's level. Can make for some dynamic music . . .
Congrats George! I love my Lightspeed. Any plans to broaden your product line?
Hi,
I used to own the very highly regarded First Sound (active) preamp which was dual mono (2 volume controls, 2 input selectors) and it had 2db increments on its volume knob. I found the 2 dB step too large a size to get the volume just right. I much prefer the "infinite" vol settings on the Lightspeed.
Hi all,
As a Lightspeed customer I came across someone saying that when it comes to nonlinear distortion in the audio range, LDR's are pretty dirty. I know that there is no perfect product, but would someone care to explain and validate this assertion please? Am I hearing the distortion at a certain vol level across all frequencies or at certain frequencies across all volume levels, or something else?
I would like to express my sincere thanks to Paul for starting this thread which connected me to George and the Loghtspeed. I hope he knows in some kind of way how many lives he touched just here on Audiogon. Your contributions and insights will be missed.