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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
 
stray_cat
Now I just need to rig up a motor with remote control to control the volume knob externally with a belt. Has someone diy this before on anything?

To go remote, you need the remote, a receiver, the motorised pot and power supply for it.
You need a dual 100kohm Logerithmic pot, and this one is just that, you could use it in the Lightspeed. (no need to use the input board with the 6 relays, just the remote and motorised pot board with receiver)

https://www.ebay.com/itm/New-LITE-MV04-Remote-preamp-board-Volume-Control-Input-Selector/11197635895...

I won’t use them myself because the reliability factor is not there, and with supply is not there either for me over a long period of time, but there’s nothing stopping owners from doing it themselves.

As for the used Lightspeed, I’ll PM the owner and see if it’s still for sale.

Cheers George
georgehifi's avatar
georgehifi
10,312 posts
 
@chakster

You sent me a PM for info PDF's ect, but for some reason I can't return to you via Agon PM with my email address in the answer as this is the only way I can send you all the info. So you have to email me on georgehifi@optusnet.com.au.

Cheers George  
chakster's avatar
chakster
6,144 posts
 
Great thread, i'm on it. 
Well, i want to read an opinions from the users of both products like First Watt B1 buffer preamp (original, not a clone) and Lightspeed Attenuator with analog source only (not digital). 

After years of using several tube pussh-pull integrated amps with vintage NOS tubes i put First Watt B1 buffer preamp with First Watt F2J (current source power amp) in my system last night. Now i have to learn more about deviced i have never heard before. 

The input inpedance of my First Watt F2J current source power amp is 50k Ohms, gain 15.6db.      

My speakers are Zu Audio Druid mk5 (101db) 

My source is MC and MM cartridges with different phono stages, headamps, suts. 

After my firs listening session with First Watt B1 and FW F2J   
i've noticed that i use 10% of the volume control on buffer preamp. I could live with only 20% of volume forever as it's already pretty lound for an evening sessions. 

In the beggining of this thread @clipsal mentioned that First Watt B1 killed his Lightspeed Attenuator in terms of dynamics. 

I hope someone else compared those two products, i hope to hear from you guys. 


georgehifi's avatar
georgehifi
10,312 posts
 
In the beggining of this thread @clipsal mentioned that First Watt B1 killed his Lightspeed Attenuator in terms of dynamics.


This could be true, in most systems the Lightspeed is a great match just like many tube pre's are, this could have been an instance where it or a tube pre's was not.
clio09 and the originator of this thread (rip) pubul57 asked clipsal what were the other components, alas he was never to be seen/heard  of again???
 
https://forum.audiogon.com/posts/75827

Cheers George
clio09
3,360 posts
 
@chakster, what phono sources would you be using? I think this will have some bearing on the result. I have heard the B1 but have not been able to compare it to my Lightspeed. I have compared my Horn Shoppe Truth buffered preamp to the Lightspeed and there is a thread here that discusses the results. Quite frankly, of all passive, buffered, and unity gain devices I have tried, the Lightspeed is the one I still use. Your input impedance on the FW amp is on the cusp, but I have used my Lightspeed with a solid state amp with a similar input impedance and had no issues.
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