I just started running the Lightspeed off a battery power supply. It is the same batter power supply used by Galibier Designs to power their turntable motors (Sears Diehard Portable Power 750), 12V DC and 12aH. Thom Mackris made me the appropriate adapter cable (mine needed to be center pin negative). I've been listening for a bit now and so far I like what I hear.
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.
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.
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- 1866 posts total
I also use a Lithium Ion rechargable sometimes, I hear a difference but cannot pinpoint what it is, even on a very hi rez system. They say the Lithium Ion has the least chemical bubble noise of all batteries. Sometimes I forget which one I have on, the battery or the wall wart it's that close. You can get these batteries on ebay from Asia for around $20 with international charger, do a search for Lithium Ion 12vdc rechargable usually made for cctv cameras were low noise is a must, just make sure it's center positive for all the production Lightspeed Attenuators I have made as I do not want to have to repair fried componets if I can help it. Yours Clio09 is the only one I think I made center negative I forget the reason why. They have about 12hrs constant use before a recharge of .5hr Cheers Georgehifi |
Mine was made center pin negative because the wall wart George recommended was set up this way. For the battery power supply you can find it here: http://www.sears.com/shc/s/p_10153_12605_02871486000P This will allow the Lightspeed to run much longer than the Lithium Ion George recommended. You will need an adapter cable that plugs into the 12V DC outlet on the unit. Here is an example of one (although they are sold elsewhere too): http://www.minute-man.com/acatalog/Online_Catalog_Cigarette_Ligher_Plugs_and_Sockets_272.html You need to scroll down the page and look for: Power Plug with 2.1mm X 5.5 mm Coaxial Plug with 18 AWG 8' Cord Item: CA205MCIGF8FT18AWG The cost is $5.95 Just make sure it is center pin positive. This battery power supply and the adapter cable are used to power the motor pods of Galibier Design turntables. These aren't inexpensive tables so I trust Thom's choice in parts. Thom procured my cable and wired it for center pin negative. |
- 1866 posts total