2. amps-preamps
  3. 1276356977

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
pubul57 OP
3,712 posts
 
Since I had the Joule LA150 SE at the time I got the LSA, I wanted another good linestage to compare it with. So a buddy of mine who has the CAT SL1 Ultimate MKII came over with his unit (70lbs!) just to compare. Well we went through some Lester Young, the Mile Davis Quintet Live at the Plugged Nickel, and some 1960s folk music. The amp I was using was the incredible Music Reference RM10 MKII.

Both preamps sounded wonderful. Could live with either. Let's say my friend was so impressed with the LSA that he is questioning whether to keep the CAT, not that it isn't wonderful, but....

What is the LSA does exceptionally well, where I really see it shine is how right it gets the timbre of instruments, wide and balanced frequency range (plenty of bass), and dynamics. I don't hear anything remotely like 2D sound staging, width, depth, and relative positioning (layering?) seems just about right. Perhaps it is simply getting out of the way and revealing with the RM10 can do - the combo may be a very, very good match.

I previously owned the CAT pre and replaced it with the Joule, after getting a good A/B comparison I still have no qualms about the LSA and its merits. And when I take cost and tube rolling into account, well - I don't think I'll be changing "preamps" and time soon, excepth maybe ot get a dual volume control version of the LSA for channel balance control.

I've not yet tried the LSA with my Atma-sphere amps because I have a lot of 6sn7s and 12au7s for my Atma-sphere preamp, and I'm not sure the M60s will be sensitive enough to go passive. But as I switch to the M60s tomorrow for the winter months, I might give LSA a trial with them.
clio09
3,355 posts
 
Perhaps it is simply getting out of the way and revealing with the RM10 can do - the combo may be a very, very good match.

That's a big part of it, in addition to remaining true to the source.

I've not yet tried the LSA with my Atma-sphere amps because I have a lot of 6sn7s and 12au7s for my Atma-sphere preamp, and I'm not sure the M60s will be sensitive enough to go passive.

They are sensitive enough, trust me.

What is the LSA does exceptionally well, where I really see it shine is how right it gets the timbre of instruments, wide and balanced frequency range (plenty of bass), and dynamics. I don't hear anything remotely like 2D sound staging, width, depth, and relative positioning (layering?) seems just about right.

The designer of my speakers top priority was getting the reproduction of natural timbre right. Putting the LSA in the chain did nothing to disrupt the natural timbre being reproduced by my speakers. It's one of the reasons the LSA is a hit with me.

I agree on the other comments as well regarding dynamics, tonal balance, and sound staging. I'll also add I notice much more how the sound staging varies by recording.
pubul57 OP
3,712 posts
 
that's the way i hear t too. i think that at this point it is not a matter of comparing LSA with others and deciding which is "best". i think it is enough to say it is well worth trying and that some folks might just find it does what they want a preamp to do (or not do), and if you are on a budget, SOTA quality is within reach of those that cannot afford much pricier, and excellent ones too, linestages. within its limits it is worthy of the finest systems IMHO.
georgehifi's avatar
georgehifi
10,312 posts
 
You are right guys the Lightspeed Attenuator (LSA) as you guys have nick named it, is the closest you will get to playing music that's truest to the source (cdp, phono ect), and the truest way to hear the way the recording engineers wanted you to hear how they have recorded the music.
As it adds nothing and subtracts nothing, like I say it is like you have plugged the (cdp or phono ect) directly into the poweramps input, no preamps at all in the signal path, yet still maintain control over the level (volume).
I accept that for some listeners it's preferable to have the added ambience, echo (if you have microphonic tubes). Also the tonal changes, because all active components have their own signature, even different brand potentiometers (Alps, Bournes, Penny&Giles ect)) sound different, compared to a direct (source to poweramp connection) gives, maybe to their ears this is preferable.
But the Lightspeed Attenuator is all about listening to the source nothing added nothing subtracted warts and all.
BTW "LSA" is a registered speaker manufacturer, hope he doesn't get the -----.
Cheers George
knghifi
1,668 posts
 
George, I don't understand how the preamp not altering the signal from the source will accomplish what the recording engineer wants you to hear? Is it even possible?

By the time the signal gets to the preamp, it has already been altered (tone controlled) by the source (cdp, phono ect) / interconnect. For me, I want a preamp to improve the signal IF necessary so the overall performance improves.

With the LSA, I much prefer my MW Transporter than TRL Sony having some tubes in the chain. Also I prefer rolling the sweeter sounding Sylvania 6sn7gt than Shuguang BT CV181-Z. So which one of the 3 the recording engineer wants me to hear? Probably none due to my inferior sources? For an end user, do I really care or just configure my prefer setup? With the VAC, I like both source almost equally despite the very very different sound.

I think a passive preamp is more dependent on a good source/interconnect than an active preamp. If a signal is poor, passive just pass through while active can attempt to improve/bandaid.

In a sound system, the signal gets altered as it passes through a chain of components. My goal is to select the combination of components that best create the sound base on my personal preferences.
More to discover