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
George, that's not going to happen.
He's perfectly content with the way his system has been voiced and the ARC pre amp is almost the least costly component in this set up.
As much as I would like to do the comparison, it's not going to happen, and I wouldn't even ask to do so.

It's always a great learning experience for me to bring over a few lps, or cd's and have a listen to them on his set up.
It is always as much a learning experience as it is a pleasurable listening experience.

Afterwards I listen to the same tunes on my system,making note of the areas that my set up falls short of his.
Then I experiment within my price range to try to improve what I have to make it sound similar to his.

Similar, yes, the same, never.

As much as the naysayers claim that only fools throw away their money chasing after the illusive absolute sound, money when spent wisely, does make for some very exciting listening sessions.

Most of the reviews people read are taken with a grain of salt,some cry foul and say they are bought and paid for.
However, until you hear some of these exotic items properly voiced, you will understand that fairy tales do come true.

You just have to pay hard coin for that experience, or find things that come close that cost much less.

The LSA is one such piece in my opinion.
I am certain Sam Tellig was never paid to say nice things about your Volume control,and it certainly isn't priced anywhere near most of the pre-amps it's been favourably compared to.

I would also like to hear what the ARC pre-amp would sound like in my system, but alas that's just a dream.My friend sets things up and that's the end of it.

I do have two friends with Acoustat speakers and the Acoustat servo amps, one a newer 3 panel (flat) and the other a 4 panel.

One uses an Atmasphere MP3, with Harmonic tech balanced cables into his amp which isn't balance, but was retrofitted with XLR jack, so it's quasi balanced and not the true measure of Ralph's genius(I used to own the same pre-amp, and it was great in a different set up with the Atmasphere S30 and stacked Quad 57's).

My other friend has the Audio Valve Eclipse, which I also owned in a different system.

So I do have personal experience with these two pre-amps when used with Acoustat amps and speakers, just not direct experience in my Acoustat set up.

Do my friends systems have anything that I think my system lacks?

Nothing, in fact, they always remark about how clear my system is.

But then I am more anal about stuff like fuses, and room treatment and the importance of clean power and using a good audio rack(Grand Prix Audio).

Because of my obsessive ways or their lack of them,I can say that the LSA is in no way shamed by either of these two very fine pre-amps, as it is set up in my system.

As I stated I've owned some pretty good pre amps(Conrad Johnson Premier two, Blue Circle fully tricked Galatea,Levinson ML2,Meitner,to name a few)but not in the system I have now.

I can only state that I have no desire to revisit them or seek out any others to replace the LSA.

It makes me happy,whether I paid $500.00 or $50,000.00,I would still find it hits all the marks that matter to me.

If I had one thing that I would change with the LSA, it would be to replace the RCA with the top of the line Rhodium RCA's from Furutech. These made a nice change on my Servo amps, and then my cables that use the 102 R Rca's would see a perfect match.I like consistency in connections,but I did admit to being anal.
Hi Lacee, you could change the gold rca's that I use and replace them if you wish with the Furutech Rhodium ones.

NB: If you want to do this let me know and I'll give you the dismantling procedure, it's not what you think, and can be tricky without knowing.

Just make sure you don't use the plastic insulation washer/s, as the body (ground) of the Furutech rca must be in contact with the Lightspeed's chassis, to maintain it being an RF (radio frequency) sheild.

http://www.furutech.com/2013/01/27/1837/

Cheers George
LDR products from Tortuga has a remote and my wife needs one. Has anyone compared the LSA to the Tortuga?
Yes we tried doing the same auto-calibration system in many different configurations all with the same negative results to the quality of the sound.

Documented years ago in diyforum, we tried many auto-calibration circuits for the Lightspeed Attenuator, to try to save a large percentage of production costs, of parts costs and labour cost and of the tedious task of quad matching the led/ldr's.

Active auto-calibration (or to give it a more understandable name) "forced matching" circuits have to be attached to the signal carrying output, there is no way around this.

On all the auto-calibration circuits we tried to save on these costs, we came to the final conclusion that they all interfered with the purity of sound. In that they added a highlighted sound to mid to high frequencies. And in effect seemed to reduce the bass a touch at the same time.

So to cut a long story short we stayed with the purer far more costlier system of quad matching all led/ldr's for the Lightspeed Attenuator and auto-calibration was not considered option no matter how well it was designed.

Cheers George