Pubul57, I like the concept of blinded sessions to remove bias. It is quasi-scientific. I think a lot of manufacturers are sensitive to the whole shootout model (blinded or not) since a poorly executed setup can talk the results and hurt their business. I am aware that most hi end audio companies in the US are mom & pop outfits, and the last thing I want to do is damage their livelihood. That being said, my pre-amp maker (TRL Dude) was stoked about the idea.
I think a second issue is pride. A lot of philes are wedded to their gear and get tribal on you fast (myself included) when challenged. At this point, I don't care about looking like a rube. If something is better, its better. The truth sets you free at the end of the day.
Prior to owning a Dude, I experimented at the level of the pre-amp quite a bit. My Wifi front end has enough juice to easily drive amps directly. I liked the sense of clarity, but the soundstage was always too flat for me. It did not sound right. In my previous rig, I used a Granite Audio 657 tubed CDP without a pre-amp. It had an enormous amount of gain in the output stage, and my system always sounded more dynamic and alive without a pre-amp. This was an experience shared by a majority of 657 owners. Conceptually, it harkened back to the 80s/90s when a straight wire with gain was thought to be optimal (by some).
Bringing things into the present tense, I discovered the TRL Dude (thanks Bill/Grannyring). It had the dynamics and sense of control of the 657 with with so much more. That being said, I am always open to hearing "more." TVAD mentioned his new VRE-1 as being a passive "with balls" and how much he is in love with that device. I did not realize that the Concert Fidelity pre was a "passive with balls" also. Dale Pitcher from Intuitive Design is using that pre at RMAF this year. I own some of his equipment and respect his ears. That being said, a buddy of mine who owns a highly modded but vintage TRL GT3 pre-amp (15 years + I believe) recently demoed both the Concert Fidelity and Lightspeed and still preferred the TRL pre. In particular, he said the LS lacked "dynamics and control."
Pubul57, out of curiosity, what pre-amps have you compared this device to? Atma-sphere per chance? Have you ever hear it with solid state amps? What is your source? It does seem as if you need fairly specific conditions for the LS to thrive.
As an FYI, I used to be a Merlin owner. Loved those speakers. Was about to purchase the ARS Filharmonia and got sucked down another rabbit hole audiophile style.... |
Publus57, the active vs. passive debate is indeed an interesting (and old) one. Many of the guys making active pre-amps today have toyed with passive designs in the past.
My crude understanding of the Lightspeed and devices like it is that its a variable resistor triggered by light. This idea is not new. Georgelofi, what is proprietary or unique about your particular design?
For end users, I wonder if the sonic signature of the Lightspeed (an oxymoron) is easily distinguishable from other passives? If you were to undergo actual blinded listening sessions, could you even pick it out in a lineup? That is a question I ask myself about my own equipment.
A friend of mine (who owns a big name active) demoed the Lightspeed and said it did a lot of things well, but it did not displace his active pre-amp. He did have some long ICs which may have sullied the demo in his mind.
For the sake of clarity and unbiased reporting, I would be more than willing to do some blinded listening sessions of active vs. passive pre-amps (in the Charlotte NC area). I will make sure to involve more people than simply devotees of the individual devices involved. |
George, for the sake of those who don't want to sift through all the technical particulars and for this thread, what are the salient features of your design? George, as a resister, how does the optocoupler compare to a fixed 1% metal film Roederstein or Vishay in terms of noise?
The actual history behind this device is interesting (and George, correct me if I a wrong). Solar cells that changed resistance with light were developed in the 50s. Audio Amateur articles mentioned the use of these cells in a compressor circuit. Audio Directions ran an article in about '75 about a dynamic range expander based on the optocoupler. This so-called optocoupler was apparently adapted from radio station and recording opto compressors.
Pubul57, so you owned the ARS twice? I was looking at pics of it recently, and it looks like the level of fit and finish is high. I was also looking at the JE Monoblocks and pre further down the road if I had stuck with the Merlins.
Tony, I agree that blinded sessions can be a mixed bag if not set up correctly. In light of the LSAs requirements, it would be easy to tilt things towards an active in a shootout. That being said, it would be fun and informative.
In terms of the VRE-1 and Concert Fidelity, I was simply quoting TVAD from your review/thread of the LSA. I was not aware of these technical specifics. I would be helpful for him to chime in.
Dale is indeed using the CF piece. I believe Hajime Sato has admired Dale's Essence pre-amp designs and speakers. I did not know there was a relationship there. Dale is supposed to have some crazy new speaker at RMAF. TBD....I wish I was going. |
Tony, that will be kool. Dale had talked about showing with Silcon Arts 2-3 years ago. In addition to the CF pre, he will be using those frankenstein tube amps, the Amber Waves. Crazy. He will also be demoing his new conditioning technology. Let me know what you think. Dale drives me to drink in terms of timeliness, but his gear is superb.
When I have more energy and time, I will attempt to slog through the DIY thread. |
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? |
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.... |
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? |
"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? |
Tvad, you logic regarding transparency is confusing. A passive is not a gold standard for transparency due to its circuitry. So, then we have to rely on the mythical Bolero Test. I am frankly amused that it even has a name. Non-audiophiles would howl with laughter if they were to eavesdrop on this thread. The Bolero test is flawed logically IMO. It is not some some empircal plumbline. A CDP is not designed to drive amps directly due to low output voltages, etc and sounds bad for a reason. As I said before, I have done this test on numerous occassions, and it sounds flat and hard and nothing like the real thing in several different systems. Why would you make that your logical frame of reference for judging a pre-amp? That baffles me. Bill very poetically described a good test for any system: live music.
An experiment along the lines of one desribed in this article would be useful for this debate: http://www.stereophile.com/features/203/ |
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. |
Tvad, that's fair. Technical limitations.
Pubul57, I was actualy asking about the LSA vs the Atma-sphere. You have two distinct systems and was curious about the strengths and weaknesses of each. Why the two systems? |
"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." George...
As I stated on the 9th, using the Bolero test to argue for a pre-amps' relative transparency or "trueness" is circular and flawed logic IMO. After rereading George's statement, the real burning question is not whether the Dude is adding an artifical depth but rather whether the LSA is simply not able to convey information that is inherent to the recording. CDPs generally suck when driving amps directly due to a lack of current (not merely a function of output voltage as some have suggested above in this thread). Current, from my limited understanding, is needed to reproduce in particular lower frequency information. When that is missing, soundstaging is effected among other things. Driving higher frequencies (tweeter) generally requires less current, and when done without proper representation of the lower frequency info, people often misinterpret this thin sound as "transparency." I myself have experienced that transitory illusion when playing direct. Ergo, a device which more closely mimics this phenomenon is not desirable IMO.
I am signing off. I will report back with results from the "Heather test." Some particulars you need to know about this particular test: I usually have to ply her with at least one glass of red wine in advance. A vintage Vera Neuman scarf (of her choosing) as a blindfold. 5-10 familiar tracks played at between 80-90 dB. Each single track will be played on each device and will be verbally labelled A + B. Just now, Heather giggled with glee when I informed her that a test has been named after her. |
As George just stated, the Bolero test is a level test only, not a tool for system analysis. Grannyring got people excited with his description of the 2D sound staging of the LSA. What followed was philosophical posturing, semantics, and the infamous Bolero test...all attempts to rationalize his findings. His findings are his findings only, not gospel as he has already said.
Pubul57, I will await winter and your comparison of the LSA and Atma gear since you are straddling two worlds and are thus somewhat double minded. That report will have the same value (or close to) as my wife's description. The "Heather test."
Larkston_zinazpic, you are brilliant. You said something without saying anything. |
Two months ago, a friend loaned me his LSA as I was curious and wanted to do a shootout between it and the TRL Dude. Like King, I also own the Samson monoblocks.
The critical "Heather test' was performed (blindfolded wife + one glass of wine as a bribe). It is an even more sensitive test than the beloved Bolero test George referenced. Result: Dude. It was not close. I live in Charlotte, NC, which gets toasty during the summer, but the Dude does not heat up the room that much, so I am not in need of a cool running SS pre. I am glad King and Pubul57 can use the LSA in that capacity.
I guess the real question now is the validity of George's statements above about bipolar resistors and the Samsons. From what Paul Weitzel has told me in the past, the Samsons possess higher impedance and gain than most amps and thus should be perfect for evaluation of a passive unit like the LSA. |
Very well said Teajay. Thanks to Paul/Pubul for stimulating people. He has an interesting perspective as someone who owns both the LSA and an active tubed pre-amp due to system requirements. That dialectic would bother me at the end of the day, but he seems to straddle the divide admirably.
George made some interesting statements about tubes and tube distortion. I love Jazz, and a lot of my favorite recordings were done in the 50s. If I am not mistaken, that means tubed mics, tubed microphone pre-amps, and tubed consoles, etc. Paul Weitzel has done a lot of recording for Sony, FIM, Fidelis and others. He produced some of the first SACD offerings and is a Grammy voter. Paul still uses tubed mics with their own regulated power supplies, tubed microphone pre-amps through a Neve console (which is known for having a warm midrange and uber gain). His recordings are some of the best I have heard. Distortion is not the first word that comes to mind.
While playing with the lightspeed and a direct drive scenario (source driving amps), I did appreciate the apparent clarity and speed. On the other hand, I noted compression of the sound stage, particularly depth, that all important third dimension. If that depth is a tube or gain-based artifact, I like it. It mimics the real thing which should be our frame of reference. |
That is an interesting experiment Tony. I wonder what the technical explanation would be for that finding? It does not make sense.
Can anyone else describe their experiences with the LSA and SS amplification? I am still wondering the flat sound staging and what that is a byproduct of? |
Not helping anyone at this point Tony. Just curious. Do you have any current or planned business relationship with George? Teajay asked that of Paul above and it is logical to ask the same of you. I know you are now attempting to design and sell tube amps now. Correct?
No LSA users with feedback on its performance with SS amplification? |
This thread has taken an amusing turn. Teajay, while you stated the obvious about George and this thread, he and his LSA flag wavers should be free to express their opinions. I have been a flag waver for different products out of enthusiasm over the years, and despite poor execution at times, the flag waving still has merits even if it is ugly. In the midst of this rather tribal discourse, useful information about the realm of passives has come out. I have always tried to keep an open mind in audio so as not to get stuck. If dynamic pre-amps are a dinosaur and sonically redundant, so be it. I am not wed to my equipment.
Audiophiles, despite throwing around a lot of pseudo-scientific jargon and technobabble, are often very undisciplined when it comes to testing equipment. Has anyone done a blinded comparison of passive units? Can anyone tell the differences between a LSA and a Truth passive behind a curtain? Would the lay public be able to say "wow, that one sounds SO much better..." I am doubtful.
I blinded my wife and had her listen to the Dude and LSA, and the differences were stark. I will readily admit that my system may not be LSA friendly. The impedance of the Samsons (68K) is ballpark based on George's parameters, but they are SS. My speakers are also not super sensitive and employ Scanspeak drivers. If I could intuit my way into the ideal LSA rig, it would be sensitive speakers (like Clio's), tube amplification, and warmer cabling (like Pub's)????
George, I tried to ask a few more technical questions earlier in this thread and and you failed to really address them and simply referred me to the DIY site which I did peruse. So, boil this technology down for us in a few sentences or less. In terms of material science, does Cadmium have a sound? Is that part of the reason why it is perceived as superior to carbon or metal? What specific measurements or measurable parameters separate the LSA from other passives or active pre-amps?
Marqmike, you made some interesting points about music and perception. I played music as a kid and come from a musical family. I have a reasonable framework for what things "should sound like." The thing that live music has that I crave for in my system is dynamics transients and an energized ambience. Any pre-amp that inhibits that, passive or active, is out in my books.
Finally, I have to comment on George's reference to testosterone. Testosterone and Audiogon or testosterone and diy don't really go together. They are like oil and water. Spending this amount of energy and time snipping back and forth about a volume control is not in the domain of manly men. I think if we all got hormone replacement therapy (and were treated for obsessive, compulsive disorders), Audiogon would start to wither.... |
Paul, I agree with all of that. Speakers and room are easy breezy. I also readily admit the the blinded A/B thing is hardly scientific in my hands as I have no dedicated switching device, etc. Most posturing on my part. lol. It was very "scientific" of you to included friends in your decision. That is good enough for me. I include my wife in all audio decision-making to protect me from me and my strong abilities at self-deception. That being said, it would be an interesting exercise to see if you could discern specific personalities of the passives discussed thus far.
I am not familiar with the music first piece. Does it make espresso as well? |
George, is the diode effect measureable? What does it do of rather what does it distort?
Paul asked the million dollar question above: what are the effects of gain? Does it produce distortion?
I did try the LSA with a SS amp (TRL Samsons) with 68K input impedance and the sound staging flattened. I have experienced the same thing when running the amps directly with my source. What is this about George? |
Thanks Al. Your elucidation of the "diode effect" was helpful and confirmed some of my suspicions.
"All active circuits produce distortion/colouration whether they have no gain or unity gain." Can you be more specific? And what about amps? Do I need to revert back to the straight wire with gain?
I have talked to two other designers of pre-amps who disagree with the fundamental premise behind the superiority of light-based volume controls. That does not make them right, but the gospel according to George is just that. Gospel to some and apocrypha to others. We need more detailed feedback from actual engineers who make this stuff. Things are much more complex than we want to admit. I know that is not going to happen for reasons stated above.
If you were to rank system components in terms of importance, where would the volume control be?
If this is a paradigm shift, it appears to be away from tubed pre + SS amps to passive pre + tube amps. The "distortion" remains. The villain has just changed clothes....
|
Next generation LSA or another opportunist copycat?
http://www.audiocircle.com/index.php?topic=97379.260 |
Recent quote from the AC thread:
"All the research I've done says users who've had both prefer the Warspeed and that this one is pretty much the best of the bunch. Curious to hear why as well, though."
and
"I could be wrong, but from what i've read it sounds like the Warpspeed LDR is the newest type of LDR to come to market. The Lightspeed is an older design. " |
That is interesting George. Why do you think the LSA is immune to a battery supply? |
Given George's explanation, it makes little sense... |
I just saw the Warspeed thread on AC and was mildly curious. They could not provide any details on "why" it was better, and it simply seemed like a me-too product. The name even tells you as much. From the listening tests mentioned earlier in this thread, the battery seems to have no sonic consequences.
IMO, George deserves all the credit for this development. It is his intellectual perseverance that has made it possible, and any "new" developments are to be viewed with a jaundiced eye.
Happy listening.... |
You find can many synonyms for the golden rule of audio used by manufacturers and end users alike. It makes for good ad copy. The problem is how you define "source". If by source you mean the recording, then unfortunately 9/10, the harm has already been done. One of the primary "sound sculpting" tools used by recording engineers seems to be compression. The rectification of that and other sins committed in the recording studio makes this hobby a lot more arduous than it should be.
For the sake of clarification, I am referring primarily to digital source material as I am a child of digital revolution. |
That's really sad and somewhat shocking. He was a true audio intellectual and contributed a lot to this site and beyond obviously. |
09-19-14: Georgelofi
It all starts with the source, in your equipment.
It sounds very good to me, and I have no wish to change it's sound or colour it in any way.
Cheers George When I hear "source," I think source material. Do "we" really want to hear all our poorly recorded and mastered music in their naked glory? I think that is one reason why people spend so much time and energy fiddling with dacs and pre-amps. |
09-21-14: Georgelofi
Maybe then for those people they should be using 100 band parametric equalizers, but then that's just adding even more electronics with their associated colourations and distortions.
And then instead of hearing the music in it's "naked glory" we are hearing sterilized distortion infused approximation. That would be a redundant gesture as much of the manipulation has already been done for you....:\ 09-21-14: Georgelofi
I know Grannyring you and Agear love your $6K TRL dude active preamp full of massive coupling capacitors that the signal has to pass through. As you both have come on strong about it very early in this thread once before.
I don't own a Dude anymore (Viva Solista integrated) so no premeditation or subconscious agenda here. I just don't agree with you. It seems there is a bit of a dude vendetta surge happening again. The late Pubul57 who started this thread warned me with an disturbing eyebrow raising email he sent to me a about you guys before he passed away RIP Paul. I tangled with Paul on this and other threads, but he always handled himself with intelligence and philosophical grace. RIP. |
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.... |
