AudiogoN Forums: Lightspeed Attenuator

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 (System | Threads | Answers | This Thread)

06-12-10

Responses (1301-1334 of 1334)

Click title to read one, or click date to read all below it.

10-03-12 By the way george, everything is fine. thanks. Devilboy

10-03-12 George built one for me a couple of month ago. it is by far ... Zmanastronomy

11-28-12 For those who want an integrated amp or preamp with a ldr co ... Georgelofi

11-28-12 George, are you saying that a diy guy like me really cannot ... Grannyring

11-29-12 Anyone can put one in a tube pre or tube power amp, but the ... Georgelofi

11-29-12 Last question. what temp fluctuations are you assuming in th ... Grannyring

11-29-12 It's more that if you calibrate for ambient ie: 15c to 35c t ... Georgelofi

11-29-12 When i take temps in my preamp (tube) i have never read temp ... Grannyring

11-29-12 I believe audiogon member dgarretson put an ldr volume contr ... Clio09

11-29-12 Thanks clio09. i will check with him and his results. Grannyring

11-29-12 Clio09, as an fyi. i now own a music reference rm9 mkii tha ... Grannyring

11-29-12 Clio09, thanks for remembering. i replaced a balanced shallc ... Dgarretson

11-29-12: Grannyring
Dgarretson, your the Man! I just looked at your system with all the mods. Very nice job indeed. I have started the whole DIY thing and am learning.

I would love to visit with you on how to try the LDR mod as well as how you made your speaker cables. I have heavily modified my speakers to great effect and completed a tube amp project by gutting a tube amp and building it back up with better parts and improved power supply. I had direction from a tube amp expert but did learn a lot. I was very excited to view your system and work.
Grannyring (Reviews | Threads | Answers | This Thread)

11-29-12 Bill, want to hear something funny. you bought your rm-9 fro ... Clio09

11-30-12 Small world indeed. Grannyring

11-30-12 Grannyring, feel free to pm me for the speaker cable recipe ... Dgarretson

12-02-12 I've had my lightspeed several months now and just tried som ... Zmanastronomy

12-03-12 I prefer a battery, but i cannot say why, if i did a blind t ... Georgelofi

12-03-12 I do not prefer the battery. i cannot say exactly why but wi ... Batalok

12-03-12 I prefer the battery but like george cannot put my finger on ... Clio09

02-16-13: Lacee
My LSA has arrived it now does volume control for my Esoteric X-03 into a pair of tube Acoustat servo amps on my Acoustat X speakers.
Previously I was using the line inputs of my Manley Steelhead into the Acoustats.
The walwart is plugged into a Hydra 8,which is connected by a Shunyata Annaconda power cord into a FIM recptacle on a dedicated 20 amp line.The Acoustats are on another 20 amp line using more Annacondas into a Furutech GDX-gold receptacle.
The esoteric has an Annaconda digtal power cord going direct into the FIM 's other receptacle.
The LSA sits on 3 roller blocks atop the hydra and is plugged into one of the Hydra's digital recptacles.

Sorry about the long winded preamble, but if Iam doing something amiss in my set up, please advise me so that I can correct the error of my ways.

Now to my intial impressions.
After only a couple hours of listening,it's easy to hear the increased amount of detail.
The issue of volume seems to vary from cd to cd , something I hadn't noticed when I listened to cd prior to the LSPA.
I tend to listen at more modest levels,so the volume control is the lower side of 9, but this is not a problem, I'll take added detail retrieval as the trade-off.

There seems to be some extra lower bass punch on some cd's that I didn't notice before, and on some other cd's I felt there wasn't as much.
That's strange.

My intial take is that the Lightspeeed doesn't homogenize the sound as much as it was before, but not to discredit the Steelhead in any way.It's just that the differences between cds are more noticeable than before, or maybe it's my imagination?

Also, I had two wal warts to experiment, one had variable plugs and voltage settings, the other was fixed.
The fixed walwart was the more robust, the other a bit more edgy, zippy, depending on the cd this could be a mixed blessing.I stuck with the fixed version.

This leads me to speculate on how sensitive the Lightspeed is to what it's power by.
I run it into the digital receptacle of the Hydra 8, but will try one of the analog receptacles.

I too wonder about what battery power would sound like after my initial runs with the two different wall warts.
I've just read George's reccommendation,a bit late as I just sent him my take on the unit before coming to this thread.

Am I happy with the Lightspeed?
Definitely yes,for the money it is great,and the single input isn't a drawback,there's better isolation between sources this way(one reason why I wanted the cd player out of the Steelhead)maybe just a minor inconvenience,as is the lack of remote volume is for others.
Personally I'll take it as it's served up,all the better for the sonics.

I look forward as the hours pass, to judge whether the sound improves , but so far I am very pleased.
Lacee (System | Threads | Answers | This Thread)

02-17-13 Hi chuck,(lacee) it is good to hear it got there safe and so ... Georgelofi

02-18-13 Thanks george for confirming that what i was hearing wasn't ... Lacee

03-01-13 I got george lightspeed attenuator directly from him and is ... Binoymehra

04-08-13 I just recieved my lightspeed this morning. first off, geor ... B_limo

04-08-13 Yep, another "normal" comment from a first time li ... Tradeontheweb

04-09-13 I use two short pairs(1.5 mtr) of heimdal from my source to ... Lacee

04-11-13: B_limo
I'm curious about that too. I'm using two matched pairs of blue jeans interconnects that sounded like poo between my dac and classe pre amp, and between my classe pre amp and classe amp. For dome reason, they sound fantastic with the lightspeed. I can't wait if it will sound better using some analysis plus or signal cables :-)
B_limo (System | Threads | Answers | This Thread)

04-11-13: Georgelofi
Hi B_limo (Bruce) , thanks for the very concise and accurate review of your new Lightspeed.
As for interconnects with it, it is always good to use good quality low capacitance ones from the output to the poweramp, as is the same for tube preamps, <100pf (picofarad capacitance) per foot is fine.(which most hi-end cables are).
Manufactures should be able to answer this, or have it printed in the specs on the packaging.
The input interconnects from the source can be whatever good ones you have handy and like the sound of.
As for the brand/construction this is more system dependent, I for my system prefer copper, some may like silver, which to me is always a tad brighter.

Cheers George
Georgelofi (Threads | Answers | This Thread)

04-12-13 Telwire from source to lsa and mogami from lsa to amp. Clio09

04-13-13 Telwire (pure copper?) mogami (pure copper?) this is what i ... Georgelofi

04-13-13 For some reason the last paragraph got edited this is how it ... Georgelofi

04-13-13: Clio09
TelWire is solid core copper, the Mogami stranded copper. I made a set of speaker cables using 1 x copper solid core combined with 1 times silver solid core per run.
Clio09 (System | Reviews | Threads | Answers | This Thread)

04-14-13 Congrats adam scott! Devilboy

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