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
What ICs are Lightspeed owners using?
1mt each each side of the Lightspeed Attenuator of Eichman Express Six unshielded.
I have found shielded cable a little constricted compared to unshielded of the same construction, I believe these days with CD high level output 2v there is no RF break-through any more. Shielded cable is just a hang-over from the low output mV phono days.

Cheers George
Either Mogami or Intuitive Design depending on the amp I am using.
George, I did end up reviewing the DIY forums and had a few thoughts and questions.

1. Are Silonex NSL-32SR2 LDRs used in the LSA? From my limited understanding, this entity consists of a Cadmium Sulphide photocell coupled to an LED within a light-tight enclosure. This is used in lieu of a traditional metal resistor and may account for (as you insinuated) for the LSAs sound. What is the typical lifespan on a LDR?

2. Does the input and output impedances of LDR-based attenuators vary with attenuation level?

3. It seems that the LSAs performance is contingent on system conditions. What are the "ideal" conditions for the LA? Sensitive speakers, short ICs, and amps with an high input impedance? One blog on the LSA I found on DMS Audio stated the following: "In a system with sensitive speakers it works amazingly well. However with difficult loads such as a power amp needing an active pre-amp with voltage gain like my Nelson Pass F5 or the F3, or using speakers under 90+ db then it is not as great. It still has the same wide sound, deep bass, detail and naturalness, but it sounds 2D with no projection. It just lacks that edge and bite of an active stage."

Your comments on this?
From elsewhere in this thread are some of George's comments:

Regarding using the LSA with low sensitive speakers, a question/answer:

Grannyring: I have a question for you owners of this exciting volume pot. Will it work well on speakers that are 87 db efficient like Soundlab speakers and other ESL's? I say this assuming the amps are very powerful and the spec criteria mentioned by the poster are meet by the source unit and amps.

George: My Martin Logan Monoliths ESL's are around 86db, I am never more than 11 o'clock for very very loud listening. I make it a point of asking customers with low efficiency speaker where the position of the volume control is for good loud level listening, and the worst was 82db speakers and he was still only at 1 to 2 o'clock for loud listening sessions.

Regarding system requirements George states:

If your source output impedance is less than 200ohm and your poweramp input impedance is more than 47Kohm then the Lightspeed Attenuator is a shoe in, no buffer will sound better.

I have read where short interconnects are best suited to the LSA, less than 2m.

Grannyring has my LSA right now and is using it with his Sound Lab speakers and Atma-Sphere amps. He's given me positive preliminary thoughts on the sound so perhaps he'll weigh in on this later.

I personally have tried the LSA with scenarios that are not as ideal as previously mentioned. For example, an amp with less than 47k ohm input and a digital source with more than 200 ohm output impedance. One thing that never happened in my usage was a change to a 2D sound stage, However, I will add that in my system imaging and sound stage are recording dependent.

I also now use battery power for the LSA. There is a difference versus using the stock wall wart, but I can't identify it. However, I will say I prefer the battery power method. Just something about it that sits better with me.
Hmmm. From an engineering standpoint, the DMS opinion on system requirements makes sense to me and lines up with the logic as applied to passives in general. Your experience contradicts his and another TRL owner how has heard it. System/ear etiology I presume....
Tony was very kind to let me play with his Lightspeed unit. I really appeciate his kindness. I will post comments once I have heard more kinds of music etc...
Keep us posted Bill. That should be interesting. I am still interested in hearing it at some point just for the sake of keeping an open mind.

Strong work Tony on your review of the LSA and Truth passives. I saw that Stereophile gave the LSA a commendation for value and performance recently. Congrats to George for the long years of hard work.

Tony, which config do you have with your LSA in the stream? VAC>>Audiokinesis or are you using that other amp listed in your system?
I have used the LSA with the VAC Auricle Musicblocs, Music Reference RM-10 MkII, and Atma-Sphere S-30. The Atma-Sphere/Audiokinesis combo was the last configuration it was used with. In all three it worked fine. In some weird sort of way I might like it with the S-30 best. It allows me the most use of the volume control. Something Ralph Karsten recommends with most passive designs.

All in all, given the proper matching criteria I think the LSA would feel at home with just about any amp/speaker combo. I don't often pay much mind to what Stereophile says but the fact the LSA even got on their radar is enough of a testimonial IMO. The fact they liked it, well its just hard to ignore the truth sometimes.

Speaking of The Truth, more to come...
Wonder what Arthur Salvatore would think of it and if it might make his Class A recommended list. He's known to favor a passive approach with the right system and doesn't give a hoot about what something costs when he associates it with a specific class.
Has anyone compared the $14,000 Music First TVC with the $450 LSA? I have to imagine that price difference has nothing whatesover to do with sound quality.
Can they put a remote control on the LSA? I'm lazy.
For those who follow Stereophile, the Lightspeed Attenuator has made it into "Class B" Recommended Pre-Amps with a $$$ value tag in the October issue.
I received an anonymous email saying if your wondering why it didn't get into "Class A" just have a look, nothing below 10K, it will never happen.

Cheers George
I could but instead of $450 it would end up costing $1450 and would then be no longer a "Stereophile $$$ value"
Quality remote, reciever, motorized pot, different power supplies and larger chassis.

Cheers George
Maybe it was previously mentioned, but can you make these with two volume knobs for left and right channels to adjust balance?
"I received an anonymous email saying if your wondering why it didn't get into "Class A" just have a look, nothing below 10K, it will never happen."

I'm not sure that is correct. If I'm not mistaken, products like PS Audio HCA-2 amplifier, the Musical Fidelity A3CR amp and the Benchmark DAC, all below the 2K price mark have earned the "class A" distinction at some point.
Maybe it was previously mentioned, but can you make these with two volume knobs for left and right channels to adjust balance?

That's what mine is. Cost difference was negligible. Of course mine is not remote. Dual volume remote I'm not certain about.
If I knew that was an option and the $$$ difference was marginal, I wold have gone for that - always good to control balance to deal with unbalanced recordings, rooms, and occassionaly speakers.
Pubul57, I know what you mean. It's my preference to have dual volume controls and when I ordered my LSA I just asked George if he could do it that way for me. I don't think it is an official option as George feels his stock design is best as is.

On another note, I have found that moving your listening position laterally one direction or another can act as a "balance control" too. We're not talking much distance here, maybe less than an inch or two and small increments make a difference.
I've used that method from time to time:)
Dual L&R controls in every PDF broucher I send out, is the only option I do. It's a $30usd option, but I tell everyone who inquires about it they are not as user friendly as the single stereo pot. As for different cd level volume change, you have to get the balance right again.

Cheers George

My LSA is on it's way. I'll be comparing it to my NAT Symmetrical and will post my observations/opinions.
That is quite a nice write up on the NAT on 6moons - it would be very interesting to hear your opinions of such a "robust" and expensive preamp up against the "simple" LSA.
I have had my LSA for about 3 weeks. George is great to deal with by the way. However my LSA is even better to deal with. I hope it doesn't have any longeity issues it is that good. Many people will mention specs, design superiorities or faults, and other reasons to make excuses for their equipment. George does not. In fact George is not positive(he thinks he knows)even why it sounds so good compared to other passives-actives and whatever in the right system. I for one find that honesty refreshing. But the proof is in the sound or listening. In my system the sound becomes a lot more colorful steeped in more accuracy of the natural tones and timing of real music. As a play around guitar player and a 35 year audiophile I hear way more of the real tags of music in persnickity audiophile terms. Equipment I have used is Jeff Rowland Consumate, Audio Research LS1, Forte 40, Sumo Athena passive/active. I don't know what could be this good. Just some old timey input. Keep up the good info on this line.
In my system the sound becomes a lot more colorful steeped in more accuracy of the natural tones and timing of real music.

Marqmike, glad you're happy with the LSA. I think you really hit on something with this comment. It pretty much describes how I feel about the LSA and IMO it's more evident now that I use it with a battery power supply. While the term "colorful" would not be one I would have thought of using and IMO traditionally goes against how I would describe the sound of a well designed passive, nonetheless I think it makes a lot of sense.

To put it another way, I think we sometimes get caught up in how our equipment performs on a linear level. I know I have been guilty of such. Focusing way too much on frequency response, imaging, sound staging, etc. Since I purchased my Audiokinesis Jazz Modules a couple years back they really started opening my ears up to things like natural timbre and timing. Things you could consider colorful versus linear IMO. In fact, the designer of my speakers had his priorities set so that reproduction of natural timbre was a high (if not the highest) priority in his design. He never set out to build a speaker that sound stages well. It wasn't nearly as high a priority. Now you might think that speakers designed in this manner add a fair amount of coloration to the sound. Well most who have heard them, including some well respected experts say they are the least colored horn designs (actually wave guide) out there. I think George may have achieved something similar in his design approach with the LSA. Something pure and true to the source, yet doesn't lose that ability to convey natural timbre and timing.

Pubul57 always stresses the importance of system matching with passive preamp designs. I made note in another thread I started as to how creating system synergy with a passive preamp could be one of the hardest things to achieve. Potentially too many variables to satisfy. However, if you can satisfy the variables, then the design of the passive becomes paramount to achieving what we experience from the sound.

I was just reading something where the following quote popped up:

"I am not so much interested in where the musicians are on the stage, as in why they are on the stage".

In my system the LSA enhances that train of thought for me.
That is a great quote Anthony, a great way to define good equipment - a lot simpler than audiophile jargon.
I think it came from a Stereophile article. Not sure who it came from though.
I have had the fortune of playing with this Lightspeed preamp/attenuator over the past 10 or so days thanks to Tony (Clio09). Thank you Tony for giving me this great opportunity. I have tried several passive units in the past and the LSA is the best by a wide margin to my ears. At least in my present system which consists of the following;

Soundlab A3 speakers (modified and improved back-plates)

Atma-sphere MA-1 Version 3.1 amps with all possible options added

TRL modified Sony SACD player (battery powered DAC)

Fusion Romance IC’s/Enchanter power cable ( 1 meter IC’s)

TRL power and speaker cables

TRL Dude preamp

BPT 3.5 Ultra with all options on the Dude, Sony and SL speakers

I compared the LSA to my current TRL Dude preamp. The Tube Research Labs Dude is a tube preamp that is priced at $3600. I have written much about it here on the Gon including a full review.

Let me bottom line my conclusions on the LSA and how it compares to the Dude. First, my comments are based on my room and associated gear and system matching is always an important determinate to consider. I do feel the LSA worked very well and “fit” in my system.

The LSA is very clean and detailed with excellent dynamics and fast and deep bass. I am quite impressed with the LSA’s dynamic punch and speed. The stage size is very wide and reflects a recording with intended large stage size. If you desire transparency, then the LSA has that in spades. For $450 it is a very good buy indeed. I can’t imagine a preamp as good for the price. I certainly have not heard one.

In the end I could not live without the Dude and now have the LSA packed up and ready to send back to Tony. The Dude simply has more to offer the listener and to the recorded music. The LSA could not match the ease and finesse of the Dude. The Dude caused the music to swell and bloom with every turn of the volume. In fact, I found myself turning the music up more with the Dude and tapping my toe. The LSA tended to sound less at ease on loud music or when the music became more complex. I missed the foundation and body of instruments that the Dude revealed.
The vocals through the Dude had more throat and weight/body.

The LSA was more forward sounding with instruments coming forth with almost spooky intimacy. Fun to listen to and very impressive. The utter transparency is quite impressive to experience. The longer I listened the more I felt the music was a tad too forward and forced onto me. I wondered if the utter transparency was also linked to a slight stripping away of the deeper tones and resonances of the various instruments and voices in effect leaving the remaining music naked and bare to the listener. (compared to the Dude) I don’t know. Some will say the Dude is adding this texture and body to the music. I am not sure I agree, but I also realize all of us have different likes and priorities in the sound we enjoy.

I just attended a symphony recently and found the instruments did in fact have more of this deeper tone and meaty foundation.

The reader must keep in mind that my Dude preamp is the best sounding preamp I have yet to encounter and has bested many an expensive preamp costing up to $10,000. It has bested some of these by a wide margin.
I really enjoyed my time with the LSA and if I did not own the Dude I am sure I would be purchasing one. The Dude has spoiled me perhaps or perhaps it is the perfect mate to my particular set of ears and preferences.
I forgot to add that my Soundlab speakers are very revealing and I would not consider them warm sounding. My Atma-sphere amps are also quite revealing and I would not consider them warm sounding. The LSA is also very revealing and with it in my system the net result may be to much of a good thing - transparency?

Just a thought....
Thanks for your comments Bill. I'm glad you enjoyed listening to the LSA. I'm missing it myself so I'm also glad to hear it will be returning to its home:)

I find your last comment on the potential for too much of a good thing an interesting one. I've sometimes felt that depending on various components being assembled, this can occur. I also sense a difference using the LSA with my Atma-Sphere versus my VAC amps. The former combination is much more transparent, the latter adding a touch of warmth and bloom to the mid-range. I'd say my Music Reference RM-10 MkII is somewhere in the middle, closer to the Atma-Sphere than the VAC. I enjoy all the presentations. One not necessarily being better than the other, just different.

Personally, ever since I listened to my first passive preamp (a custom built K&K Audio TVC) I have felt active preamps are additive (some may offer more transparency than others, but in the end they are adding something to the mix). I even felt this way with my old TRL preamp. In the end that's just my opinion and I'm sure there will be some disagreement on that from others here as we all have our preferences.
I should also point out that the LSA is a champ at bringing all of the detail and parts of the music into the front row. I was hearing instument lines that on my Dude were more muted or set-back. Some may really like this. This is what really got my attention in the first hour or so of listening.
I was hearing instument lines that on my Dude were more muted or set-back.
Grannyring (Reviews | Threads | Answers | This Thread)
That to me is an indication of the LSA's transparency and faithfulness to the source, and a lack of transparency in The Dude. By transparency I am referring to lack or presence of coloration.
I have no doubt the LSA is truer to the source than any acrtive linestage. Whether being true to the source sounds better or not to a particular listener is another question that nobody but the listener can answer. What I think the LSA offers, is the ability to eliminate a step in the chain, so that you are left with source,amp, speaker to define the system's sound - it simply gets out of the way, and the source - amp - speaker interface is free to define the sound, without the the preamp acting as a chameleon with differtent systems, the LSA simply gets out of the way, better than any other preamp I have tried, and that makes it transparent on not a coloration to be played with in the system as a whole. Because it is so transparent, or absent, it will alter the choice one might make between source and amp - but for what it is designed to do, it seems to me it does it extemely well. You want warmth, change your amp - the LSA does nothing but make the music louder or lower - don't expect it to flavour the soundscape in any way - it won't do that - it is the color of water.
Straight wire no gain? LSA the watercourse way (sic)? Lead, follow, or get out of the way? Sounds likes the LSA fits the bill;) However, it doesn't fit everyone's preference.

In any event, with the LSA we're not only left with the source-amp-speaker interface, we're left with the recording engineers/musicians preference. I have never heard a preamp that exposed that extra variable into the mix like the LSA.

True to the source? Perhaps...
"That to me is an indication of the LSA's transparency and faithfulness to the source, and a lack of transparency in The Dude. By transparency I am referring to lack or presence of coloration"

Let me further explain as I think my statement needs more context. I feel it is a matter of taste and not accuracy at all. The LSA plays the instruments more up front and forward - and I mean all of them! The instruments play on the same plane at the front of the speaker. Some may like this. However, to others it is a lack of 3D perspective or depth.

The Dude plays music with greater depth and not all the instruments play on the same forward plane. Some are more set back and not as "up front" on the performance stage. The performance has more perspective and depth. If the recording offers only a forward perspective for all the players, then the Dude reveals that. If the recording is more layered, then the Dude gives that deeper layered presentation.

I found the LSA made my favorite recordings all share that same forwardness for all the instruments. In other words, every recording began to take on the same personality with all the music coming from a plane at the front of the speaker. The whole of the music seemed to be traded off or lost as the vocals and instruments all competed for attention at the front of the stage.

When I attend a symphony or other great sounding live music events I hear instruments positioned differently on the stage with many of them at differing volume and intensity levels. The Dude seems to reflect that reality more. This is exactly what I mean in my statements above. To my ears, in my system, the Dude is every bit as transparent as the LSA, but the Dude seems to possess more fidelity to the space and dimension of the musical experience.

Rather than compare the two which only I can really do based on actual experience, I do find one topic very interesting. Some feel that an active preamp is adding warmth or coloration to obtain a richer sound that is somehow not really in the recording or live musical event. The conclusion given by those is that this richer sound experience is not as accurate or true to the recorded source. This can certainly be true of some active tube units, but not all.

In my experience live music delivers the whole of the instrument. Listen to a grand piano, cello, violin etc… or entire symphony in a great sounding venue and you will hear the rumble, resonance and totality of that instrument. You will hear the orchestra swell in full and rich momentum with a solid deep foundation underlying the whole musical event. Is that added? Is that coloration? I don’t think so. That is what I hear with the Dude. This is what I find missing with the LSA in comparison to the Dude. For me this is critical to reproduce in my home music system. Again, for me alone this is important and it may not be to others. Is a passive missing this part of the music? Is it missing what was intended to be there? Is it actually playing what is recorded and the recording does not sound like the live event? I suppose the last point is possible, but my desire is to hear instruments as they actually sound in a natural setting.
I am not sure a passive is by some mathematical or physical fact the best way to achieve live sound in our homes. Let’s face it; all gear and wire in our systems are reproducing or passing along electrical signals no matter the set-up; Active or passive, tube or SS, horn or ESL, simple or complex and on and on it goes. I don’t think that a passive or active unit is ALWAYS the definitive best means to hearing the wholeness of a musical event – not missing depth, bass foundation, warmth, dynamics, crashing of a cymbal etc…. I cannot accept a sweeping statement that passive units are the best means to live music recreated in our homes. They may be in a particular system to one person’s ears, but that’s about as far as we can take it.
Ok, have it Agoners!
"found the LSA made my favorite recordings all share that same forwardness for all the instruments. In other words, every recording began to take on the same personality with all the music coming from a plane at the front of the speaker. The whole of the music seemed to be traded off or lost as the vocals and instruments all competed for attention at the front of the stage."

That is a very telling statement. I have audiophile friends who believe any pre-amp is a bad pre-amp and should not be in the chain. I fall into active camp. I would be interested to hear how staging and dimensionality is an artifact from a technical standpoint.

I too will be getting an opportunity to hear the LSA and compare it to my TRL Dude. That should be fun. More importantly, I will involve my non-audiophile, musician wife in a blinded listening test between the two and will report on her findings rather than mine.

Tony, you referenced owning a TRL pre-amp. That was Paul's prototype of a battery-powered, solid state pre right? Not a Dude. Out of curiosity, did you ever hear the LSA side to side with that entity? Are you speaking from sonic memory?
Grannyring, your further explanation further reinforces the idea of the LSA preamp being less colored than the TRL preamp.

If one accepts the definition of a passive preamp as a device that passes the source’s signal unaltered, except for attenuation of gain, to the amplifier; and assuming a proper impedance and gain match between source, LSA preamp, amplifier, speakers and cabling, then one also accepts that the recording is being reproduced as if the passive preamp were not in the system at all.

Therefore, if there is a difference in the reproduced sound with a different preamp (in this case an active design) in the system; and assuming again a proper match between the active preamp and the source, amplifier, cabling and speakers, then one must conclude that the active preamp is responsible for any difference one hears, and that the difference is a result of an alteration of the source signal beyond volume. This alteration is coloration, or lack of transparency.

If one doesn’t accept the basic premise above, then the discussion regresses back to the beginning.

There's no right or wrong choice of preamp here. However, based on the descriptions being posted of the two preamps, I can only conclude that the LSA preamp least alters the source material.

Now, if a listener prefers The Dude because it appears to reproduce a recording more like what one recalls hearing in a concert hall, then the discussion becomes one of preference, and there's little point to debating preference.
The LSA plays the instruments more up front and forward - and I mean all of them! The instruments play on the same plane at the front of the speaker. Some may like this. However, to others it is a lack of 3D perspective or depth.

Bill, was this true of every recording or was it recording dependent? I do find with the LSA in my system it exposes the recordings for what they are. Meaning some have a more 3-D sound stage than others. Some are also more immediate in their presentation than others. However, I can't recall one where all instruments are in a flat plane at the front of the speaker. What specific recordings were you listening to?

If the recording offers only a forward perspective for all the players, then the Dude reveals that. If the recording is more layered, then the Dude gives that deeper layered presentation.

Exactly how it should be with any preamp, active or passive.
That was Paul's prototype of a battery-powered, solid state pre right? Not a Dude. Out of curiosity, did you ever hear the LSA side to side with that entity? Are you speaking from sonic memory?

It was the Pre-1.5 battery powered preamp and no, I never compared it with the LSA. My comment was a blanket comment on all the active preamps that I have heard since I have been exposed to what well designed passive preamps can do in ones system. To me they are all additive (some more so than others), not necessarily in a bad way, as I do enjoy listening to some active preamps. Again, it's my opinion and anyone can feel free to agree or disagree. Perhaps the Dude is different and maybe some day I'll get to hear it for myself and come to my own conclusion. After all I lent my LSA to Bill so he could do exactly that.
I have not heard LSA but have used the same LDR resistors to provide variable cartridge loading in a modified phono stage. LDRs are about as clean sounding as the best nude Vishay, Caddock, and tant resistors, so I imagine they would make a first class passive.

Regarding the allegation of "forwardness," assuming that we are not talking about strident aggressiveness, the quality of forwardness in a top component is often a good thing in the sense that the piece sounds more alive, faster, dynamic and resolving. The listener is literally closer to the music, in fact the stage may extend both forward of and to the rear of the speakers. In this scenario depth-of-field cues are delivered through high resolution. Instruments appear layered in depth more by virtue of low-level cues than by soundstaging per se. The more astonishing hat trick may be when a system throws instruments outside the L & R speaker boundaries, or does a perfect job of imaging intentionally-recorded phase anomalies to the side of or behind the listener. Some of this is contingent upon room characteristics, but with great electronics it can be surprising how much of it can be pulled off independent of room.
Interesting article by Robert Harley in the 2011 Buyer's Guide (TAS) on audio vocabulary - including "fowardness" and "laid back".

What I find with the LSA is that soundstage and imaging changes with the recordings - that to me is a good sign.

One thing for sure, there is simply no arguing preferences, unless you really want to start a winless argument.

What is not arguable in my view is that the LSA provides a very high level of sound quality at a very low price point (for the hobby).

Glad to see that some folks are giving the LSA a try.
Perhaps the 2D forwardness speaks more to my system synergy then to anything else. This may well be the case as I have no way of really knowing.

Tvad's point is understood. I guess I always felt the point of a good stereo system was to recreate the sound of music as faithfully as possible to the source - human voice or instrument. I am suggesting a preamp/attenuator is indeed part of the path from recording to ears and always plays a role regardless of being active or passive. Since it will always play a role and has impact on a stereo's ultimate sound, then it's always a means to an end in a total system. The end is, for me, Van Morrison's voice sounding like Van Morrison, a piano sounding like a piano etc...


10-09-10: Grannyring
I guess I always felt the point of a good stereo system was to recreate the sound of music as faithfully as possible to the source - human voice or instrument.
I think the disconnect here is the definition of *the source*.

If I understand Grannyring correctly (and I'm willing to admit that perhaps I don't), he is referring to the source as his conception of how the voice or the instrument would sound in an ideal live setting. He asks himself if what he hears coming from his speakers approximates how he envisions it would sound in the concert hall or club or studio.

When I discuss the source, it is always referring to the software...the recording. Not all recordings are faithful to how the voices or instruments would sound in an ideal live setting.

None of this is to suggest that I prefer one over the other. In fact, I vacillate on that.
10-09-10: Grannyring
Quote>Perhaps the 2D forwardness speaks more to my system synergy then to anything else. This may well be the case as I have no way of really knowing.

What you should do Grannyring to see if the Dude is artificially giving depth, is what I preach all along, put your CDP straight into your poweramp (Bolero Test) no preamp. Put on a quite cd so you can then ascertain a good level of cd to play, then swap in the Lightspeed then your Dude and see which is closer to no preamp. The one that is, is the one that is truer to the source.

BTW the English and some Aussie speaker manufacturers back in the 70's & 80's use to purposely -3db the level of midrange units to give the illusion of greater 3D depth.

Cheers George
Hmmm. An explosion of words. I will add to it with my own verbal diarrhea.

I have a few questions:

1. Pubul57, you started this thread (a good one a might add), and you are in a good position to speak to the attributes of passive and active pre-amps. You appear to own both (LSA and Atma-sphere). Any observations on differences between the two particularly in light of what Bill has described?

2. Tvad, you stated the following:

"Grannyring, your further explanation further reinforces the idea of the LSA preamp being less colored than the TRL preamp."

I am unable to follow your logic here. Bill's description does not do that at all.

"If one accepts the definition of a passive preamp as a device that passes the source’s signal unaltered, except for attenuation of gain, to the amplifier; and assuming a proper impedance and gain match between source, LSA preamp, amplifier, speakers and cabling, then one also accepts that the recording is being reproduced as if the passive preamp were not in the system at all."

That is a definition only. The LSA uses components which can "influence sound." If anyone takes the time to review the DIY threads as I did, you will discover a few things about the LSA in this regard. The LDRs, which appear to be the heart of this unit, functions as a variable resistor, and according to some, have their own "sound" which contrasts with traditional metal resistors, etc. Furthermore, based on one gentleman's measurements, the impedance of the LSA varies with degree of attenuation: "Similarly, the Lightspeed's simulated output impedance varies from about 37 Ohms to about 14.6 kOhms, as the attenuation level is varied from maximum to minimum." derived from http://www.diyaudio.com/forums/analog-line-level/159163-
ldr-photoresistor-attenuator-preamp-general-2.html

So Tvad, you cannot make those simple, blanket statements in regards to active pre-amps. Both influence things from an engineering standpoint and thus potentially influence sound.

3. Tvad, you made the following statement in Tony's review thread discussing the LSA and Truth passive:

"Those who are considering the $18,000 Concert Fidelity CF-080 might also consider the US made SMc Audio VRE-1, which is also a "passive with balls" ($14,950)."

A passive with balls? Why does a passive need balls? It would be very interesting to get your impressions of the LSA vs your VRE-1....
Great post Dave.

Regarding the allegation of "forwardness," assuming that we are not talking about strident aggressiveness, the quality of forwardness in a top component is often a good thing in the sense that the piece sounds more alive, faster, dynamic and resolving. The listener is literally closer to the music, in fact the stage may extend both forward of and to the rear of the speakers. In this scenario depth-of-field cues are delivered through high resolution. Instruments appear layered in depth more by virtue of low-level cues than by soundstaging per se.

I have a recording that illustrates this very well. The soundstage is very deep, yet the piano is quite forward in it. The vibes float effortlessly in the middle with amazing lateral movement. On some tracks the soundstage does in fact exceed the speakers. The CD is The Wonderful World of Ron Carter and IMO is well engineered. Anyone who enjoys jazz trios with excellent bass playing should look into it. The music will certainly give your system a lower frequency work out if nothing else.
I don't know of one resistor based passive that doesn't vary the output impedance based on the attenuation level. I think it is just the nature of the beast and as Andrew mentioned the LDR design is not immune to this (Side Note: The Truth Preamp does not vary the output impedance but that is because it uses active buffers on the outputs). It is one of the reasons why it is important to get the right impedance matching and in some cases to pay attention to cabling to attain the best sound from such a design. TVC passives have the same issue (see here, scroll down the page http://www.stevens-billington.co.uk/page102.htm) but are more forgiving. It was one reason I preferred TVCs earlier on before encountering the LSA.

Also, Ralph Karsten mentioned a number of times that the best sound from a passive will occur closest to the maximum point on the volume control (least attenuation). That is because the further around the dial you go the lower the output impedance. I'm never at much lower than 12 o'clock on my LSA and with my Atma-Sphere S-30 amps where I can vary the input sensitivity and gain, I'm never at less than 3 o'clock. So it's safe to say I'm operating at lower output impedance running into high input impedance amps (minimum 100k ohm, maximum 250k ohm).
Tvad, you understand me correctly. Sorry I should have been more clear perhaps. Further, so we can get on more common ground around this topic, I feel the software/recording used to judge accuracy should be one that is very close to live sound - a great recording. This gives a good base in which to judge the system. If I have heard a given brand/type piano in an intimate setting on many occasions I have a good sense of how its sound. When I listen to good recording of said piano on a system, I am in a good position to judge that system's accuracy.

If it sounds thin or lacks body, then I know that system is not getting it quite right in that particular area. I now understand this system will behave the same way on any recording regardless of the recording's quality.

A recording may be heavy laden with warmth and body, but this system will play it with less of those attributes and therefore not be true to the recording.

I have good recordings of piano and Van the Man and have seen both live on many occasions. Based on this I prefer one system over another.
George, it does not make sense to state that system synergy manifests as 2D or 3D. Please explain.

"What you should do Grannyring to see if the Dude is artificially giving depth, is what I preach all along, put your CDP straight into your poweramp (Bolero Test) no preamp. Put on a quite cd so you can then ascertain a good level of cd to play, then swap in the Lightspeed then your Dude and see which is closer to no preamp. The one that is, is the one that is truer to the source."

I have done that test repeatedly. Digital done direct (Bolero Test) always sounds flat, hard, and 2D. Not like real life at all. Not sure what that specific test adds.