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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
 
lordcloud
Has anyone made a balanced version? Is it possible to purchase a balanced version?


I've tried many different ways all a compromise, or not reliable over time.
I don’t do them and I suggest you don’t use them.
It can’t be done reliably in the "purest" way of making the Lightspeed Attenuator circuit that gives it it’s magic, and also ask it to stay in calibration over time.
https://www.diyaudio.com/forums/analog-line-level/80194-lightspeed-attenuator-passive-preamp.html

It can only be done with active force matching circuitry that’s a compromise to the sound in itself, and "can" damage one or more of the 8 led/ldr’s in the long run from over driving them to keep up with the stronger ones.
Your better off using xlr to rca adapters as my customers use when they have no rca connections, only xlr, these works great.

https://www.parts-express.com/xlr-female-to-rca-female-adapter--240-428

https://www.parts-express.com/xlr-male-to-rca-female-adapter--240-438

Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 

One thing that I didn’t mention, was that xrl only sounds better than se over very long distances.
In many cases se actually sounds better, if an opamp was used to make the xlr circuit in your equipment, and you’d be very surprised to know just how many do it that way in many hiend products. .

Cheers George
vladas
2 posts
 

I am so impressed with Lightspeed Attenuator. HUGE sound improvement!!


With 80-85% of regulated analogue output on Oppo UPD-205 player and around 11-12 clock on Lightspeed, I am getting MUCH more balanced, realistic and pleasant sound. This is with mild to medium speakers' loudness which I use 95% of the time. Improvement is very obvious across all sound spectrum, but is extremely obvious in the voices.


I always pay paramount attention to the voices. To me, if the voice is compromised, nothing else matters.


In comparison, without Lightspeed (or with only 20-25% of regulated analogue output on Oppo UPD-205 player and max volume on Lightspeed), the sound is MUCH less articulated, less pleasant and less realistic. This is very obvious in all sound spectrum, but is extremely obvious in voices. Again, this is with mild to medium speakers' loudness which I use 95% of the time.


Blue label on the Lightspeed box is a great match to other blue lights in my audio. Very thoughtful, George.

 

Audio system:

Voltage stabilizer: Line-R; Cawsey power cleaner;

Aurealis: speaker cables and copper interconnects Litz Dragon;

Oppo UPD-205 player/streamer; Lightspeed attenuator;

Cymer Audio Southern Star SE-35 power amp;

Osborn Epitomes Elite speakers.

vladas
2 posts
 
Important Update:

1. I think Lightspeed Attenuator is not an accessory, but a MANDATORY component for most audio systems because the difference is unbelievable.

2. I believe that DUAL volume control is a MANDATORY. It is very useful not just for vinyl records (which half of audiophiles don't use), but nearly for EVERYTHING: to compensate room settings; to compensate your sitting position; to compensate inferior audio recordings (common); inferior sound recording in movies (very, very common). 
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