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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
esmith904
3 posts
 
tradeontheweb thanks for the guidance.  I may try the battery option too as a fun experiment.  I've started out powering the Lightspeed with a Teradak power supply. 

I hadn't done any upgrades to my setup in about 10 years since I recapped my AR9LSi speakers with audio grade film caps.  I thought I was done, but started sensing something was holding me back recently.  I started researching what folks were saying about the components that I already had and discovered folks saying the Adcom GFP-565 was not very good.  Glad I found the Lightspeed.  It totally makes sense that putting  more active components between the music source and the amp risks adding more noise to the signal.  It would have been another long journey to buy and try a bunch of different active preamps.  The Lightspeed has also rekindled my audio bug too.  Will be looking  at further upgrades or mods to my other components, but the Lightspeed will remain at the core.
mickstuh
2 posts
 
In answer to your question Georgehifi , my speakers are Be-One, model: The One. No one has ever heard of them; well, not in the West. I heard them and bought them. I have only ever found one reference online, by a reviewer (an amateur, I think), who had them as his reference speaker. The site where I read that seems to have died. The brand is Chinese, and have a website beone-audio.com. It often works. My speakers have been discontinued, and removed from the site. They most resemble the BO-8, which has one less driver per cabinet. I have never heard their amps, but they do look gorgeous! Hey, if you are ever in the Dandenongs ...
georgehifi's avatar
georgehifi
10,312 posts
 
mickstuh
  beone-audio.com
 my speakers are Be-One, model: The One. No one has ever heard of them; well, not in the West. I heard them and bought them. I have only ever found one reference online, by a reviewer (an amateur, I think)
http://www.beone-audio.com/eindex-1.htm
Wow these guys look to make some good stuff, a bit like Usher. Some of the speakers are very Sonus Faber influenced.

Cheers George
toddverrone's avatar
toddverrone
840 posts
 
Man, that FR88 is a straight focal copy.. looks nice though.
georgehifi's avatar
georgehifi
10,312 posts
 
tradeontheweb
esmith904

I dug out some noise measurements for you guys I did on the noise floor of the output into 50kohm load.
It was on the absolute limit on my Tektronics test gear to measure down that low.

And with the Linear powersupply it was 50uV P/P (micro volts peak to peak ), this is around ten times lower that the best active preamps I’ve seen, which are sometimes in the mV (millivolts)

Then I did the same using a pure battery supply, and yes it did come down a touch from 50uV to 30uV, this could be the reason some of us hear something when using battery but can’t explain what?

But a difference of 20uV (micro volts) noise is practically nothing?? I can't point my finger at this and say this is what we're hearing though.

Cheers George
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