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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
hammering
1 posts
 

Hi all. Just a short note to let anyone who may be interested how I came to buy a Lightspeed Attenuator.

I bought a Halcro MC 20 power amp which was on special from Magenta Audio in Adelaide and being a power amp, I had to find something to adjust the volume and putting out 400 watts per channel, I figured I could go passive. A Google search turned up George Stantscheff and his amazing Lightspeed Attenuator.

It simplicity (and price) impressed me so I took a chance and bought one. It has turned out to be one of my better hi fi choices.

I'm running a Sony SCD XA5400ES sacd player thru the Lightspeed, Halcro amp and into a pair of three way floorstanders with Audax drivers and the sound is so "pure" and clean, I feel there is nothing in between the source and the amp.

Last year I started to set up a pc based music system and bought a Benchmark DAC2 HGC that I connected to the digital out of the Sony to replace the Lightspeed and it delivered the music in spades, but after a couple of hours it began to fatigue me. After a week of using the dac I took it out and replaced the Lightspeed Attenuator and restored the clean, open sound I was missing.

So I think I'll not bother with the pc based music system for a while.

Keep it simple!!

miller65
3 posts
 
My Lightspeed Attenuator now a few months on from purchase is still proving to be a superb purchase . I have been experimenting using a cheap Breeze Audio Linear power supply against the wallwart supplied with the unit , I have used this unit for the last month or so and believe it just shades the wallwart . However the unit has a led display and was originally set to 9v DC output showing 9.2v when originally connected ,  I have however noticed recently the display is showing what I believe is referred to as ripple and varies from 9.20 to 9.23 often changing every second or so , does anyone know if this is normal . I thought the whole purpose of a linear regulated power supply was to give a specific voltage without fluctuation and also would ripple potentially effect  sound quality ? I have searched the internet but any explanation given is above my understanding .
Finally battery seems to be an option has anyone had any positive results using a battery supply ? notice you use one George I am also interested in other users feedback

georgehifi's avatar
georgehifi
4,966 posts
 

Hi hammering, you echo the responses of so many owners when you said.

"It simplicity (and price) impressed me so I took a chance and bought one. It has turned out to be one of my better hi fi choices."

This "kiss" is the way I like to keep it, to get the source signal to the poweramp/s with the least amount of colourations.
Rather than using preamp circuits, input switching, and volume controls ect, which all add their own set of signatures and colourations.

You should also give the $29 battery a try that I posted in my last post, as it is the purest way of powering the Lightspeed and will last a good 3 weeks before a recharge is needed, and please give us an A/B comparison if you get one between it and the supplied linear wall wart.

Cheers George
georgehifi's avatar
georgehifi
4,966 posts
 

I thank you also miller65 for your glowing response to your purchase of the Lightspeed Attenuator.

As for your question: "I have however noticed recently the display is showing what I believe is referred to as ripple and varies from 9.20 to 9.23 often changing every second or so , does anyone know if this is normal."

This will not effect the performance of the Lightspeed, as for two reasons, the Lightspeed itself also has an internal regulated 5vdc supply it runs on, so any slight fluctuations from your external supply will not have any effect on it’s stability, secondly the 30mV fluctuations you have on the display could be due to slight temp variations inside your Breeze Audio Linear power supply.

What you should do is also get the rechargeable battery I posted 2 posts back, as it will be the purest most stable noise free way of running the Lightspeed, and give us your opinion on how you like it’s sound, as for just $28 it’s a cheap experiment, and will leave no room for doubt as well. As we all know audiophiles have doubt if there is a question mark with anything, and it can eat away at our senses sometimes.


Cheers George



edbrux
1 posts
 
I bought two LA 's from George and I would want to share with you my experience.
I have in the past a numerous of preamps and my last one was a Audio Research LS 26 : having listened to the Lightspeed Attenuator I sold it.
The LA is so much better.
The LA may at first use sound " a little  britlle "  but when the impedance matched correctly it is amazing good and it beat all the preamps I had before.
Between my Audio Research DAC 8 and my Pass Labs amp it is a perfect match.
I am very happy with it - I can only say : try it
Thank you George.
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