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
Would capacitance be offset by higher source output?

I ask because since I put a chordette qutehd dac into my system, the volume position for normal listening went from 11 to 9 or 10 O'clock.
Cable capacitance will not influence the overhaul volume level, but it will effect the high frequency -3db roll of point.
eg: If you have 1mt interconnects from the Lightspeed to the amp that are 100pf, the -3db is at 227khz
If the the 1mt interconnects are 300pf the -3db is then at 76khz.
Your Chordette had more gain (output level) than what you were previously using to change the normal volume level on the Lightspeed from 11 o'clock to 10 o'clock

Cheers George
I have been hearing for years CD source directly conected to QUAD II (15 wts valve amplifiers) and refusing any preamplifier between, therefore I had not any distortions but also not any control on volume. I have not perceived any change or coloration on the sound introducing the Highspeed attenuator between. So the question is not if highspeed is better than other preamps, the fact is that it seems that does not exits in the system. So, I have not improve farther the old almost optimal configuration but I have gain to be able to enyoy music without neighnours problems
So going to order this LS. My Placette makes noise for some reason when plugged in.
So going to order this LS. My Placette makes noise for some reason when plugged in.