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
This is a strange hobby, and the hobbyists are a strange breed.

Some folks are content to listen to their music collection and not worry themselves if a power cord or a PSU will make an improvement to what they have.
They are the ultimate music lovers,while some of us, myself included,fuss over the smallest of details trying to squeeze that last drop of performance out of our systems.
Such types are mostly frowned upon,their enthusiasm about superior performance when changing one type of wire for another is met with more than a bit of scepticism.
"Don't such people know that if two wires measure identical they should sound the same not different?"
"The only difference between a stock fuse and an upgraded fuse is the cost.Soundwise there should be no difference."

On and on it goes.
The endless "I heard it" and the response"no, it just can't be".

Some of us have heard the improvements the TeraDak makes over an off the shelf wallwart, which as stated by someonelse, probably is a SMP device,the linear ones seem to be harder to find.

Battery power would appear to be, in theory ,to be the ideal.I once owned a Sutherland PHD battery power phono stage, my friend has a Nighthawk battery power phono stage.
Yes, getting off the grid does have it's benefits,but battery power isn't the magic bullet, ticket, to sonic nirvana.
It takes more than a battery power supply to bulid a good anything.

Not trying to disparage any of the above products, or anyone's based on battery power, but there is a lot to be said about how those batteries are implimented into the design and how good the design of the product is in the first place.

Running a device that is well made, and designed with top components will trump an inferior design with cheap off the shelf parts.
Because both are battery powered, doesn't mean they will be on the same playing field, and sound the same.

I would think that there are the same quality variations between such battery power supplies as there are with anythingelse.Some better than others.
Or you may feel that they should all sound the same.

The PHD doesn't sound like the Nighthawk,or my Steelhead, nor should it.
Yet the non battery powered unit with tubes,doesn't send any kind of hiss or residual noise thru my system, so it's as dead quiet as the battery unit was.
If that was the only thing to consider, then you could say that there is no difference between battery power and grid power.Or that it makes no sense to spend any extra money if the Nighthawk is as quiet as the PHD.

A SMP is said to be noisier, inferior to a linear unit, and the linear unit is said to be the equal of a good battery supply.
The LSA demands such little juice that how one can hear any differences at all between any of the devices is hard to believe.The power supply shouldn't really be of importance, just as long as it meets the specs.
Less would be bad, but more is overkill.

I'm not sold that it's the noise from a SMP supply that was robbing me from all the dynamics that I now enjoy.
The system sounds as noise free as before.
Just like the Steelhead is a noise free as the PHD was.
There are other things to be considered,not just noise cancellations.
I'm just a listener,not a techie.
But I'm not suffering from tunnel vision either or am I the slave to measuring devices.

And yet here we are discussing those very differences and merits between a cheap wallwart or a bit more expensive PSU being used with an entry level priced volume control.

Chump change to the those who play in the big leagues and ponder if another ten grand on interconects over and above the ten already spent,would have made the difference they were looking for.

I have no idea what the cost is for a decent battery power supply for the LSA, and what the lifespan/cost is to keep one running at it's optimum.Or if it gradually powers down or abruptly shuts down.

So I would think that if a linear supply sounds close, then that would be the one to go for.

I have no ideas why the TeraDak performs so well in my system.
Granted it's getting more support from what it's plugged into than most other LSA in use.

But that's getting back to the top of my rant.
The LSA is not priced as a High End performer,so the systems it maybe used in, perhaps reflect the cost constraints of the owner.In other words,it's cheap, but in cost only.But it's cheap, why throw any money at it?

I think if the thrifty music lovers, (who are always looking to cut corners to free up more cash for music software),and buy the LSA, will most likely partner it with gear in the same price spectrum.

And for those folks,expensive power cords and power supplies are unjustified for musical satisfaction.

So in essence, they are selling the LSA short from my perspective.

And in my opinion,so are the folks who own the LSA and power it with a SMP wallwart into a power bar.

From my recent experience it deserves to be treated with the same regard for power demand as any of the mega buck high end components, and will benefit just as much.Eventhough it only requires a minimum amount of power to work, don't take it for granted that it can not be made to work even better.
It's power demands are few but don't hold that against it.
Given a better power supply, the LSA is an even better giant killer.
Thanks Lacee. I am glad George recommended this PS and that you and Banquo263 have used it. So now hearing about its positive effect it is on my list to get as soon as I get my new innerconnect, Amadi Maddie Sign., in my system and broken in. Thanks again.
Thanks Clio!

Well put Lacee. I'm no skeptic when it comes to upgraded power supplies or power cords; they've all made improvents in my system, so I don't know why I'm skeptical over an upgraded power supply for the lightspeed (maybe because someone (George?) said that rubbing two sticks together is enought to power the lightspeed, lol. I'll be getting a teradak next month to compare to the battery pack I'm currently using.

Now if there was a way to harness all the damn static electricity in my house, I could power all my equipment for free...
Hi guys: haven’t viewed this thread for a couple of yrs at least (since I bought a LSA, after the gracious, generous help of Pubul57, Clio09, and George).

Maybe you are interested: I upgraded my LSA by wiring the power supply direct to the board (removing the psu connector). It was beneficial, but relatively so long ago I can’t be specific about what difference I heard.

Oh, I also replaced the RCAs with WBT NextGens to (supposedly) impedance match my WBT NexGen/ICs, and added a separate earth lug to the LSA chassis, that is wired (separately), directly to the green mains Earth wire behind a dedicated mains outlet (so the LSA is like a star earth in my system. I tried in vain to get George to add an Earth lug when I purchased).

(It gets worse! I also rewired my LSA with the same silver litz of my ICs.
But other than the psu wired direct to the board, it’s all far too laborious – I’m not even sure I should mention it!)

I’m using the original supplied wall wart psu, so your discussions re power supply are v interesting. Seemingly its sm, according to George's suggested AM radio test which gets noisy when brought close to it.

Thanks guys for the interesting posts.
Sorry part of my earlier post was premature.

"I’m using the original supplied wall wart psu, so your discussions re power supply are v interesting. Seemingly its sm according to George's suggested AM radio test, which gets noisy brought close to it."

I believe I misinterpreted noise: George's info says he supplies a linear 12vdc supply - thats what I've got. Please ignore my "Seemingly its sm," line.