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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  (System | Threads | Answers | This Thread)

06-12-10
  Responses (1051-1100 of 1334)
Click title to read one, or click date to read all below it.

12-22-11   You would think the real market for george's attenuator woul ...   Pubul57

12-22-11   I surmise that's a slippery slope...unless its patented. im ...   Dpac996

12-22-11   I think it is patented, in fact i think george has already n ...   Pubul57

12-22-11   Good. then all is right in the world. we need more people li ...   Dpac996

12-22-11   What i did was to stop someone else from trying to patent it ...   Georgelofi

12-23-11   Happy holidays to all!   Pubul57

01-04-12   I have a question regarding the relationship between a cd p ...   Grannyring

01-05-12   Input impedance is 10k ohm.   Clio09

01-05-12   I have a cd player with 2 volts of output, but the only spec ...   Grannyring

01-05-12   Do you have the trl modded sony 900? if so you might want to ...   Clio09

01-05-12   I just looked at the manual and it appears the audio output ...   Clio09

01-05-12   Thanks. yes 10k is very high. as you saw the manual uses the ...   Grannyring

01-05-12   Happy new year to you all, the 10kohm load impedance that so ...   Georgelofi

01-05-12   Thanks george. i will not be able to measure it so will have ...   Grannyring

01-05-12   If 10k is the minimum load the sony is comfortable seeing an ...   Clio09

01-07-12   For sony to quote that this unit should see 10kohm or higher ...   Georgelofi

01-10-12   Next generation lsa or another opportunist copycat? http: ...   Agear

01-10-12   I think george addressed this 09-29-11 - after i asked a few ...   Pubul57

01-10-12   Recent quote from the ac thread: "all the research i'v ...   Agear

01-10-12   Yes, it would be good to hear from someone who has actually ...   Pubul57

01-11-12   It's all good to add fancy ways of not having to quad match ...   Georgelofi

01-11-12   As you noted earlier in my question about an improved versio ...   Pubul57

01-11-12   Dual l&r volume controls are the only option i provide for t ...   Georgelofi

01-12-12   Or ears:)   Pubul57

01-13-12   neither. the designs are more different than the same. not ...   Clio09

01-13-12   Agear, seems like your have you answer. the "latest&qu ...   Pubul57

01-14-12   Does the ls improve with the battery option? curious what yo ...   Grannyring

01-15-12   I wouldn't say the battery option improves the sound, but th ...   Clio09

01-14-12   I just saw the warspeed thread on ac and was mildly curious. ...   Agear

01-15-12   I would also like to hear other opinions about this from own ...   Georgelofi

01-15-12   One less thing in the world to worry about:)   Pubul57

01-15-12   That is interesting george. why do you think the lsa is imm ...   Agear

01-16-12   Because all the supply has to do be it battery or mains, is ...   Georgelofi

01-16-12   I have the battery supply as well. it changes the sound, slo ...   Batalok

01-16-12   Given george's comment, it would seem the burden of proof is ...   Pubul57

01-16-12   Given george's explanation, it makes little sense...   Agear

01-16-12   If you know led lights, you would know they are an extremly ...   Georgelofi

01-16-12: Almarg
Perhaps the reason some of you are reporting sonic differences between using battery power and the wall wart is simply that volume levels haven't been precisely equalized for the comparison?

I realize that the LSA has an internal regulator, but no regulator is perfect, and so perhaps voltage differences between the outputs of the battery and the wall wart result in slight (fraction of a db) changes in attenuation, that need to be compensated for with the volume control.

To totally rule out the possibility that the sonic differences are attributable to volume changes, I believe that the levels should ideally be equalized to within around 0.1 db, which is probably impossible to do without instruments.

Best regards,
-- Al

Almarg  (System | Threads | Answers | This Thread)


01-16-12   Al, that really makes sense. and it seems to explain clio9s ...   Pubul57

01-16-12   Al, if the voltage output of the battery and wall wart power ...   Clio09

01-16-12   Anthony, no, i was assuming in my last post that both suppli ...   Almarg

01-16-12   Sorry guys the internal regulator in the lightspeed attenuat ...   Georgelofi

01-18-12   So taking any power differences to the led's out of the equa ...   Georgelofi

01-18-12   Given george's good answer about noise level, and his answer ...   Almarg

01-18-12   It is linear. i, we?, sometimes hear what i expect to hear, ...   Pubul57

01-18-12   In the february issue of tas, neil gader interviews john mcd ...   Pubul57

01-18-12   You find can many synonyms for the golden rule of audio used ...   Agear

01-19-12   When i say source,i mean the recording, not the live event - ...   Pubul57

02-03-12   All you proud lightspeed attenuator owners, look out for the ...   Georgelofi

02-03-12   Talk about pride of ownership;). i will give both my lsa's a ...   Clio09


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