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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
clio09
3,372 posts
 
I have used the Lightspeed with both MC and MM cartridges. No issues whatsoever. With MC I use 68db gain on my phono stage and the Lightspeed is at about 2 o'clock or so on the dial. With MM I use 42db gain and the Lightspeed is at 11 o'clock or so on the dial.

I have even used the Ligtspeed with an amp whose input sensitivity is nearly 3V. I even doubled the sensitivity to nearly 6V and in both cases the Lightspeed worked fine. at 6V I was pretty far around the dial, but that is what the amp manufacturer recommended having tested a Lightspeed on his own.
clio09
3,372 posts
 
Great sound does not have to cost a lot. Great looks are nice to have, but it doesn't necessarily equate to great sound. Convenience seems to be something many audiophiles want, but a remote or multiple inputs can do more harm than good. Tubes are fun to play with, but can inject noise or colorations.

We get to make our choices and we get to live with the results, for better or worse.
pubul57 OP
3,712 posts
 
Anthony, I agree. There are many reasons to own a full-featured, robust active preamp and yes, even the "audio jewelry" aspect is as legitimate as any other reason for prefering a piece of gear.

What I am missing is the "active" argument solely on the basis of sound in a system with appropriate gain and impedance matches. There was some conversation earlier on about "true to the source", and by that I don't mean true to the live event being recorded, but true to everything in the signal coming out of the source (e.g. CD player output) - at least once removed from the live event - but anyway all the rest of the system has to play with. It seems to me that if anything is different, in any way, from the direct connection, it is an artifact and not true to the source. I won't argue that some, many may prefer the sound of those artifacts, and they are perfectly right to choose according to their ears and preferences, what I don't think can be argue logically is that any active preamp, no matter how expensive, can be as "true to the source" as the Lightspeed Attenuator (assuming proper gain and impedance matches). There may a difference in preferance based on accurate versus pleasant, and we are all free to choose the camp that makes most sense to us, and that choice can't really be argued with. I would though argue that a neutral preamp can be mixed with the widest range of sources and amps, which are then left to present their own sonic signatures.
darkmoebius
900 posts
 
09-09-10: Clio09
I have used the Lightspeed with both MC and MM cartridges. No issues whatsoever. With MC I use 68db gain on my phono stage and the Lightspeed is at about 2 o'clock or so on the dial. With MM I use 42db gain and the Lightspeed is at 11 o'clock or so on the dial.
What was the output of your low MC's? (maybe I screwed something up, I'm a vinyl newbie)

The 0.25mV 103D into my phono pre+active stepup's 64dB gain yielded 0.4V, that just didn't cut it into either of my amps, especially the 1.5V monoblocks.

I suppose other important factors would be size of room, sensitivity of speakers, listening distance from speakers, musical complexity, and desired listening volume.
clio09
3,372 posts
 
What was the output of your low MC's? (maybe I screwed something up, I'm a vinyl newbie)

Dynavector 20XL low output version rated 0.25mV. However, mine was going into amps whose sensitivity was rated 1V and 0.7V respectively.

As for being a vinyl newbie, maybe I'm mistaking you for someone else, or maybe the vinyl set-up listed in your system is a mirage. However, I've been to that pictured location in San Pedro listed on your system page (I think you've moved since then) and bought one of your two Scheu turntables at the time. Having two of those tables, me thinks you're probably not a vinyl newbie, but hey, when it comes to vinyl set-up we all make mistakes.

Try again and see.
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