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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
georgehifi's avatar
georgehifi
4,966 posts
 
You have no gain worries now then, just flick the gain switch on the back of the Ayon to 5v go direct into the Krell from it and you will have the most transparent/dynamic sound you can get this way, with a bit of gain to spare.
If you find yourself using the Ayon's digital volume too far below 1/3 of full up, then you can order a Lightspeed Attenuator, turn the Ayon full up and have the second most transparent/dynamic sound you can get.
Wished you would of told us all about the Ayons gain switch and that you had it on 2.5v instead of 5v would have saved a lot of research and guess work.

Cheers George
photonman
96 posts
 
what kind of case is the LSA built with as it looks like some type of casting in the pictures and not the usual bent sheet metal?
audiolabyrinth's avatar
audiolabyrinth
4,483 posts
 
@ Georgelofi, Hi, The Ayon 2s sounds better on the 2.5 volt setting for some odd unexplained reason!, Like I said, I have played around with the toggle switches on the back of the player for days on in!,I also do not believe turning my system up to loud volumes on the 5 volt setting is very smart to do, considering the balanced input on the Krell is 3.3 volts or so!, This will not do nothing to the amp it can not take, my speakers, I wish not to damage those!, A 3 1/2 volt didgital player would be perfect!, LOL!,,, I do appreciate your time to talk to me here, It is very special when a componet designer takes time like this out of their busy life!,, Gratitudes to you!!
georgehifi's avatar
georgehifi
4,966 posts
 
You are correct Photonman, they are made of extruded aluminium, not sheet metal as you can see in the picture.
lightspeedattenuator.com

Cheers George
georgehifi's avatar
georgehifi
4,966 posts
 
Audiolabyrinth hi.
All the gain 2.5v/5v switch is doing is changing the feedback resistor on the output buffer to another value to give 5v instead of 2.5 on the same output buffer.
As far as being concerned that you have 5v out feeding into 3.5v in, this is quite acceptable, as if you had an active preamp in the mix you would have far more than that, as some are capable of giving out up to 20v or more out.
So as you can see it is not out of the ordinary to have more out than what's can go in, just means you have a bit of headroom, just be judicious with the volume control.
And like I said if when on the 5v setting you are below 2/3 of full volume then "Bit Stripping" can become an issue. Then you can get a Lightspeed have the 5v full up and the Lightspeed will be at or around mid 12o'clock position for normal listening with more available if needed. Or you can leave the Lightspeed at say 2o'clock and be able to use the remote volume on the Ayon to raise and lower the volume within the top 1/3 of full up, this way you will not be "Bit Stripping"

Cheers George
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