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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
10,312 posts
 
No negative impact using a remote, but no improvement in sound either, but there is a negative impact using any form of input or output switching.
It has has always crossed my mind to do a remote volume, but as it is the Lightspeed Attenuator has 99.9% reliability for minimum dollar expenditure.
Put in a remote receiver sensor circuit, a motorized pot and a good quality remote control, plus another 2 power supplies one for the receiver circuit and one for the motorized pot. And you have diminished that reliability by quite a bit. Plus you need a bigger chassis to house it all, and you have increased the price 3 fold. The cheap skates are already complaining about the $470 shipped price, can you imagine if it were to go over the grand mark.
I have a "KISS" reflection every now and again to bring me back to earth to make me realize why it is such a good product to begin with, and if it ain't broke don't ---- with it.

Cheers George
pubul57 OP
3,712 posts
 
Reliability is golden. I certainly would not be interested in paying 3x for remote - I'm really not that lazy:) What about the idea of LDRs at the amp input - no IC? Endler Style Attenuators with the superior Lightspeed LDR attenuator.
clio09
3,360 posts
 
I have the EVS attenuators and the concept is pretty sound in terms of being able to put them at the amps inputs. Not sure you could get the LSA to accomplish the same thing since each unit would probably be larger in size than an EVS or Endler making them a tight or impossible fit on some stereo amp inputs (monoblocks should be much less problematic). Not to mention I assume each will require it's own power supply or share a power supply that sits off to the side somewhere.
pubul57 OP
3,712 posts
 
You know Anthony, it just might be that the LSA is what it is and the way it must be:) Some of the DIY community seems to be hell bent on "improving" the LSA - it's just possible it can't be done - without trade off - thought it would be nice to get rid of the ICs. One less thing, but as you suggest an added element of complexity.
clio09
3,360 posts
 
The only other possibility is to put it inside the actual amp at the input. It would require enough chassis space, but it can be done. This is Ralph's approach with the passive attenuator upgrade for the M-60 amps and up in his line. Unfortunately not enough room in the S-30 or Iwould have opted for it.
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