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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
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banquo363
371 posts
 
George,

When I wrote "warm up use time" I meant actually used to play music. My LSA is already always plugged in and at half position (per instructions), but I've noticed that irrespective of that, my vinyl always sounds better on the second side (and beyond). I've tested this by playing the first side over again--always sounds better the second time. It's not my phonostage (which is always on) or my amp which I switch on, without fail, at least an hour before use. To be clear, this is not a complaint but rather just an observation. The other belief, that the LSA is getting better over time, is also entrenched. I'm no true believer in burn-in time or whatever it's called, but I can't help but notice that the LSA keeps delivering more beautiful music with each passing week. I can't explain either phenomenon; I don't care to.

Fiddler,

It may be friendlier than tubes, but one weakness of the LSA is its one input design. I understand and appreciate the argument that more inputs would be sonically compromising, but if I didn't primarily use my turntable, I would find constantly switching interconnects a serious pain.
georgehifi's avatar
georgehifi
10,312 posts
 
So if he doesn't like Fets or Mosfets the input stage to the Samson must be bi-polar, it is not tube as it's all solid state.
This means the Lightspeed Attenuator is maybe not giving 100% of it's self, if the Samson is bi-polar input they (poweramps with bi-polar inputs) are usually below 30kohms input impedance.
We have found in listening tests with many "golden ears" that the Lightspeed Attenuator just starts to compress the dynamics slightly at 33kohms, 47kohms was fine, indistinguishable right up to 200kohms.
Cheers George
clio09
3,355 posts
 
It may be friendlier than tubes, but one weakness of the LSA is its one input design. I understand and appreciate the argument that more inputs would be sonically compromising, but if I didn't primarily use my turntable, I would find constantly switching interconnects a serious pain.

Like you I also play a lot of vinyl, but do listen to CDs and on occasion my tuner and reel tape deck. At first changing the ICs was inconvenient, but I got used to it. I had done some research on input switchers. You can get them pretty cheap, but if you're concerned about sound degradation Decware makes one for $119:

http://www.decware.com/newsite/rotary.htm

This has 6 switchable inputs. You could probably get them to make you one with less. Steve is pretty flexible. I know, another set of interconnects. Well the Decware ICs are fabulous for the price. All told you'd be out less than $300. Consider it the price of convenience.

Of course if you want to splurge then the 47 Labs input chooser is the one to get:

http://www.sakurasystems.com/products/47selector.html

A cool $850.
tsciame
88 posts
 
Hey George,

Have you ever thought of setting up your own forum. After all this thread is getting real long in the tooth and one input does not a preamp make, even if it is the best ever.

Cheers
Tony
clio09
3,355 posts
 
If you think this thread is long in the tooth go over to the one on DIYAudio. It makes this one read like a short story.
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