2. amps-preamps
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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

Showing 3 responses by miller65

miller65
3 posts
 
Although I read a lot of hi fi forums this is my 1st ever post and the only time I have ever really thought about posting , the reason simple the Lightspeed has simply transformed my system and I now believe I am getting the best out of the other components . The following is the mail I dropped to George after listening to the Lightspeed for only a few days ;

What a super piece of kit just goes to show some real bargains still exist in the Hi Fi world and you do not always have to spend a fortune for the best quality components , without doubt the best value for money I have ever spent , thankyou.
Previously I had used active preamps in my system originally a Naim 62 with Snaps power supply and then an Avondale 821 but I was never totally happy with the sound which always sounded a bit muddy and lacked in detail , so I started on my trail of trying passives of which I have had 2 over the past 12 months , latterly an Audio Synthesis Passion which was a decent improvement in terms of detail retrieval but did lack some of the dynamics I got with the Avondale .I really thought to obtain the sound I craved I would need to spend mega bucks but after much reading decided to give your Lightspeed a chance and wow from the first few minute I plugged it in it sounded just superb , I always thought the preamp was holding back my system but the increase in transparency dynamics and detail retrieval far surpassed any upgrade I have ever made in my system ! I did consider various types of passives including Transformer based preamps but so glad I made the decision to try yours ! which I very much doubt could be improved upon at any price .
For the record my system comprises Marantz CD63 heavily modded , Avondale S100 power amp and ATC SCM 7 speakers with Mark Grant interconnects.
George in my mind your product is the bargain of all time in Hi Fi terms and will be my last ever Preamp , once again congratulations on a great product
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

miller65
3 posts
 
Thanks George the temperature variation in the power supply makes sense as it is more stable in line with a stable room temperature I also intend trying with a battery in the next few weeks.
As a next stage I am considering using my CD player as a transport and introducing a DAC into my system this will also enable me to include a network player at a later date. However having checked the output spec of the DAC Beresford Caiman mk11 I have a couple of questions in terms of how output impedance can effect the sound quality . The output voltage of the DAC is 2v which is in line with LSA recommendation but the output impedance is 1k ? appreciate it should be 200 ohms or less ideally . Iwill use with a very low capitance Stager silver solid i/c 0.5 metre length .
Does anyone have experience of using the LSA with output impedance this high and if so what if any effect can it have on the sound / volume control . I love the transparent dynamic sound the LSA currently gives me and wonder if this potential impedance mismatch would have any adverse effect on the sound quality or use of the volume control which 
currently operates at 12 o clock , which is generally plenty loud enough

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