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
I have sat in front of many systems that measure great but sound rotten. So, I have no need to help out poor Sam Tellig, just to point out that techno-babble that says the same thing over and over again on this thread does not prove that George's LSA is in some objective way better then active linestages.

Then why reference him? What was the point? Are you just trying to point out someone that has an opinion that agrees with yours? A lot of people do. You're right in some respects our ears are the judge and it's obvious there are quite a few people who prefer the LSA on this thread, for whatever reason they wish. Like you prefer your Black Box but scientifically can't explain why.

If you have an objection to George posting here well deal with it. It isn't the first or last time it will happen on Audiogon. I welcome manufacturers opinions.
Hi Paul,

I believe that you have always been a gentleman who has contributed much to the GON members with your opinions, knowledge, and experience with different pieces of gear.

That's not a setup to now get you, I really believe what I just said, however I think your just a little bit obsessed with the the topic of passives vs active linestages. As you know I have had some of the highest regarded transister and transformer passives in my system and liked them very much. As my taste and ear has evolved I found in the context of my system they did not perform at the same level as great active tube based linestages. As I shared with you in an E-mail I and a few friends auditioned the LSA and found it OK and to my taste not as musical as John Chapman's TAP passive. My remark that you seem a little bit obsessed with this topic is that you state correctly that passives offer great bang for the bucks, what you call stupid/good, that you numerous times restate why they will or might not work for technical reasons which are quite informatice and correct and go into all kinds of nuances why you prefer the LSA in your system. How many times are you going to restate what you have stated over and over again on this your thread until it seems that you are, to me, just wee bit preoccupied with this topic?

You have NEVER said the LSA is for everybody and all systems which I have great respect for, however, good old George has said many times on this thread there is no doubt that his piece is better than any other based on measurements and keeps pushing this assumption in a way that I found quite obnoxious for an AudioGon forum thread.Yes, he states that certain parameters must be meant regarding gain and impedence, but if these are in place there is no reason to ever consider listening anything but his creation. He then goes back to his scientific test of running your CDP straight to your amps being careful not to blow your speakers apart as an objective /scientific test to prove his point. Oh please, you don't say anything like this but he does over and over again to promote his product. This is what I would refer to as an example of technobabble that tries to prove objectively that LSA is superior to all other preamps.

Paul, we both know there is no BEST in our hobby and I don't believe we are even disagreeing about this. I'm not entrenched in an either/or position on passives or active linestages being the best, just how the designer comes across in a way that I find dogmatic, not you, and how many times the same stuff is brought up until it seems like a commercial ad, instead of a thread to educate members about an inexpensive way to get great sound for alot less money.
Especially when you know that an opinion being opined is in fact that of a manufacturer, a dealer, or some other person with a financial interest on the topic - which does not discredit what is being said, but does provide the necessary and expected transparency of where the opiner [?] is coming from.

George thinks he has a great idea, and will argue its merits. Other are free to challenge his technical claims, and others are free to describe their experience with the LSA, good or bad, a revelation or a disappointment. Nothing wrong with that, or public scrutiny....
Hey Clio09,

I get a kick out of your phrase, "well deal with it", as if I'm losing sleep over the drivel that George keeps pushing for his own finacial gain.

I believe that you have entrenched your self in a position for what ever reason to be an advocate for good old George and what ever my opinion is you will attack it and disregarded any information I share. I accept we will never agree, so it's a waste of my time to try to explain anything more to you.

For an example of friendly and good natured rational discourse on this thread, take a look at how I and Paul try to discuss things in a respectful manner even though we do not see eye to eye on some aspects of this topic.

So I'm done with you, Good Day
"...George keeps pushing for his own finacial gain."

How do you know what George's motivations are? Maybe you should set up a psychic hotline.

Seems to me if a guy was interested in financial gain, he would price his unit more in line with other passives (read: higher priced) and that same guy wouldn't put his design out there for free on DIYaudio.com.

Doesn't make much sense does it?

Next conspiracy theory...