Lightspeed Attenuator - Best Preamp Ever?
Hi Paul, Yes, your speculation regarding my use of SS amps (Threshold&Pass Labs) with a tube based preamp in my system vs your use of tube based amps with a passive preamp makes sense to me. You get what tubes have to offer the body of the harmonic, soundstage layering, and at least for me with the right tubes more natural sounding timbres with your power amps and I get it out of my tube based preamp and tube based DAC. |
Hey, hey , hey guys. I personally like the LSA to anything I have ever heard, which you can see most of that is on my previous posts. I have experience with real musicians in real space and real time. And from that perspective I find on most non-musician friends and others systems there is to much concern with the 3d thing and spacial ques, it is out of proportion to what I find in real space. And I feel it effects the tonal response of the whole recording and the timber of the instruments and voices. I say sure you can hear a fly land on the back wall of the auditorium but that is not what I listen to a recording for. But the truth is we all live on our own worlds when it comes to music and its reproduction. And that is fine and good. |
Hi Paul, Something else I wanted to share with you but I forgot to mention, is my experience with many tube based active linestages is that the ones that use a rectifier tube in the power supply sound much more natural/musical to me then preamps that are totally SS in this section of the power supply. Again, I don't know why this should make that much of a difference from a technological perspective but my experience has been that it sounds much better then a SS power supply. |
Terry I have heard that said about power regulation and believe it, my experience too - seems like those old technologies seems to still work pretty darn well:) I do think we are on to something regarding passive and there use with SS versus tubes (in addtion to the fact that SS will generally, but not always present a more difficult impedance load). I always wonder about folks that have tried passive and find something lacking (besides noise:)) - I always thought that some of that must occur if the impedance/gain/IC capacitance issues are not properly. Now assuming all that is fine, than I can see why those using SS amps and no tubes in the chain might also feel something is missing (and it may very well be a form of distortion - but one I like and makes me happy). Oh, well, play around with this stuff is [more?] hald the fun! Marqmike, I too find that much of what we look for in recorded music through our systems regarding 3D, imaging, spacial cues, etc. is simply not there in live perfomance, or at least far less than we seek it in our systems. What live music brings that no stereo system I've heard truly replicates is timbre and dynamics - every time I go listen to unamplified live jazz, I go home and remind myself to accept that while I love my system and listening to music on it, it is not the same as live (really, how could it be?) but a facsimile. |
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.... |
"Would the lay public be able to say "wow, that one sounds SO much better..." I am doubtful." When it comes to preamps, amps with sufficient power to drive the speaker, and cables of any ilk, I would say you are 100% right. The difference between speakers however (and room placement) would be pretty obvious even to the most leaden, "untrained" of ears. |
Disciplined testing? I don't know. Just kept switching between preamps with the same 2-3 "test" tracks for a week, over and over, brought audio buddies over to minimize the possibility I might be hallucinating, and I (we) enjoyed the LSA every bit as much as much as my relatively expensive tube linestage and so I decided to save the $7000 and not worry about tube replacement (I have enough of them to worry about). Not science exactly, but enough to make a decision. Hard since the linestage is probably the #1 recommendation by the speaker manufacturer for his speakers and the one he uses at shows, and I certainly loved it - but still....I also have no phono, and no switching requirements. |
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? |
One correction to Agear's very interesting post. The Truth is an active buffer, not a passive. To answer his question, I am not a betting man but in a blind test between the Truth and LSA I would bet I could pick them out. This is not to say my hearing is that good, it is to say I have spent so much time listening to these two preamps that I know them that well. Each do a couple of things really well that my test tracks would allow me to pick the correct preamp. Now if I were not as familiar with them then all bets are off. I would probably have a difficult time picking them out. It took me quite a while to figure out the nuances of each unit when comparing them. Pubul57 - I tested the LSA against the Audio Consulting Silver Rock. It was evident that the LSA just got out of the way of the music, like it didn't even exist. In some ways it was a similar experience to something Himiguel wrote in an earlier post here. It was like I could hear the Silver Rock's signature, whatever was causing it to have one. The LSA was obviously the more neutral and truer (purer) preamp. |
09-16-11 Agear: George, 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? :09-16-11: Agear Ager, It may very well be the most transparent sounding resistive substance, their is no way to measure this. But I believe the Lightspeed Attenuator to be "the truest to the source" way of controlling the volume because their are no contacts (diode effect) in the signal path, this is why darTZeel has used them in their $24k NHB18ns preamp, also Constellation Audio with their $60k Altair preamp uses them as well. All I can say Ager is with the Lightspeed Attenuator you get the closest to the sound of having your source directly connected to the poweramps, yet with control over the volume, it adds nothing and takes away nothing when implemented properly, it is "true to the source" Cheers George |
Anthony, your description of the LSA versus the Audio Consulting, is similar to my impression of the LSA compared the K&K with S&B and BENT w/Slagle AVC - all superb in my system, but the LSA seems to do less, in a good way. I wish I could listen to the Placette Active that I bought from another fellow on this thread, a wonderful piece too and one that really does not require a whole lot of thought about cables or impedances - perhaps more universally great - no idea why I sold it - OCD? probably. |
Paul just looked at your system, that is a Esotar D330 tweeter in your speakers? I fell in love with that tweeter when I listened to a pair of Sonus Faber Extremas, it was the first time I liked the sound as much from a dynamic tweeter as my preference for ESL's for high frequency repoduction. Cheers George |
Yes, and probably why I have stuck with Merlins for 9 years, or 187 years in audiophile years:) Thinking about passives versus actives all these years, it brought me back to the words of the Master (aka, NP) describing his Aleph L line stage (manual) which was passive till the 3:00 position on the volume control... "Above 3 o’clock, active gain is added to the output signal in 2 decibel increments, for a maximum of 10 dB. As a result, you suffer the effects of active circuitry only when additional gain is necessary." Raises the question as to the the "effects" are, and when is gain "necessary". Clearly sometimes both are necessary and preferable, and sometimes not. For some reason, as I get older I want less to get more, but no less than necessary. |
Pubul57: Raises the question as to the the "effects" are, and when is gain "necessary". Pubul57: With today's sources, cdp, dacs, even phono stages, there is clearly no need for added gain in most systems. As what most sources can give out today in volts and current, they can easily overdrive (clip) most of today's amps. So all that's needed is a way to attenuate that source no need to give them more gain with the added colouration of what an extra gain circuit gives, only to reduce it back down again to below what the source originally gave out. Cheers George |
From reading A. Salvatore's review of the Coincident Preamp, I get the idea that it is not trivial to discern whether the source can deliver sufficient current and volts to make an active preamp unnecessary. After all, for more than a decade he believed his source was sufficient but it turned out, by his standards, it was not. I take it then that if his observations are correct (a big 'if'), then one cannot merely look at a spec sheet to determine sufficiency. The question is, what more is there to look at? One can do the Bolero test, but Salvatore did it and it gave him the wrong answer and misled him for a long time. What then? |
George, I think we are in agreement, as Anthony is likely to be, and it might seem Nelson Pass is likely to be in agreement too, and yet we find many(?) audiophiles that still don't see it that way, and I respect their view as well, but I guess I am just comfortable with my own conclusions, theoretically and in actual listening - and whatever divergence of opinion we have seems like an uncrossable bridge, so we are left with try it and see what you think. But the argument is also between a $500 approach versus 5-20K approaches, so where do you go from there? I don't know. I can only recommend that folks try it and decide for themselves. |
I should add: what else should we look at other than impedance matching concerns, which concerns I assume Salvatore knew about and also are not enough to determine sufficiency. As Paul suggests, we are left with trying out different equipment. But unlike trying out the LSA, trying out different active preamps is typically an expensive proposition. |
Need to look at the voltage output of the source compared to the voltage input needed for the amp - sensitivity rating. This is also very important. An active preamp will be needed if the amp's voltage need is higher then the source's output voltage. I also think current plays a role and can limit dynamics in some set-ups. |
09-17-11: Banquo363I should add: what else should we look at other than impedance matching concerns. If the impedances are right, nothing, so long as the dac or cdp has volts high enough to clip/overdrive the poweramp which nearly all have, and enough current which nearly all have, except some tube output dac's and cdp's. Look at any of the user manuals of the higher end dac's and cdp from Wadia going right back now to the late 80's that had digital domain volume controls in them. The manual states going direct into a poweramp with any of these units will yield a superior sound than going through any preamp, so long as the digital volume is in the top third so there will be no bit stripping. There are no preamps inside these top Wadia's I have personally seen inside a few of them they are just like all other dac's and cdp's on the market, with a current to voltage conversion stages after the dac chips then output buffers to the rca's. The Wadia's magic happens before the dac chips, in their propriety filtering techniques and receiver stage . Cheers George |
In the Aleph L manual, NP goes on to say, "If you need gain, above the 3 o’clock position the volume control provides 2 dB of gain per step, for a maximum of 10 dB. In this region you will be listening to the active circuitry of the Aleph L. As an interesting experiment, you may want to try listening to the difference between the straight-through position and the next higher one, seeing how well you can discern the character of the active gain system." The tenor of his comments seem to speak of the effects o gain stage as producing flavors, granting that even straight through might have a signature too. It always brings me back to Ken Stevens design goals for his (CAT) preamps, he said he wants the "flavor" (his word) to be like water - in his mind, no flavor. As for gain, I an tell no difference between my 2v and 4v settings on my EMM player, other than I turn back the volume control a bit. So we are left with. Passives are.... 1. Always better than actives 2. Never better than actives 3. Sometimes better than actives No lover of passives in general or the LSA would argue 1. - that would be foolish and clearly not the case. It seems hard to argue 2, since some folks with a long history of fine active line stages of considerable merit hear things differently and prefer the passive, their judgment not swayed by a lack of resources or inability to have tried the options. It does seem 3 is the most likely case and it it raises the question -- if so, when? Under what circumstances. I think this thread has provided enough guidance as to when a passive, and possibly the LSA best of all, will provide a quality of sound comparable to the very best available - for a fraction of the cost - as long as it is not made in Switzerland or ensconced in a 2" inch aluminum case. |
This is also very important. An active preamp will be needed if the amp's voltage need is higher then the source's output voltage. I used to think this too until I tried my LSA with my Atma-Sphere S-30. Source = 2V and S-30 = 2.8V - nearly 6V depending on how it was configured. In either case the source did just fine driving the amp via the LSA. |
Actives also need to be well matched with the amp. My cuurent tube active was a poor match to the Sunfire Signature amp which has an input impedance of 24k ohms. The bass was muted and highs were etched. The Sunfire amp does not sound this way at all nor do my speakers or pre. I inserted a modest SS amp with an 100K ohm input impedance and all was much better.My system is magic again. Impedance matching is also important for actives. I think most, if not all, of our opinions of actives vs passives are based on the synergy of the system they are placed in. It's the total system stupid:-) |
09-17-11: Grannyring Actives also need to be well matched with the amp. My cuurent tube active was a poor match to the Sunfire Signature amp which has an input impedance of 24k ohms.Grannyring Yes Grannyring, tube output active preamps are just as susceptible to poweramp impedances as passives are. I looked at what Teajay is using. The output stage of his Concert Fidelity CF-080 is a 12AU7 in cascode configuration direct to the SE output rca's, I thought this is a high output impedance. So I checked with our tube gurus, they confirmed to me for this tube to be use in this configuration in it's best linear way, it's output impedance will be around 33K! And at best it will only give 10mA maximum output current. This is fine if it sees a poweramp with 100k or higher input impedance, but he is using it into a Pass Labs XA100.5 which has 20k SE input impedance??? Bad Match this one!! Cheers George |
Sorry George, You have two mistaken assumptions regarding my system. First, I use Pass Labs XA-60.5's and not the 100.5's. Secondly, and I think more importantly, since I biamp my system any preamp I use active or passive the signal is first directed to a Bryston X-over then to my two pairs of monoblocks to drive my MG-20's. Therefore, your premise regrading a bad impedance match is invalid in my situation. I have no idea regarding what the impedance rating is of this active X-over, just that your LSA did not play music in my system like CF-080 does regardless of the reasons why. |
George, I'm sure by reading this thread you know my position on your posturing regarding blatant promoting of your piece along with your arrogant know it all attitude towards anyone who does not see the the light of the purity of your passive linestage. So, when you make another snide remark like,"needs to do their homework before spending the big bucks," it fits into what I would expect from you based on your past posts on this thread. I have no idea how you experience music or how well you hear. All I know is that your LSA for my ears' was no better or worse sonicly then other passives I have owned in the past and came no were near the the performance of my active preamp regardless of your comment regarding the concern over the impedance of the X-over. Finally, I have never asked for your advise or your opinion, your minions are quite happy to keep asking for it or you provide it on a on going basis to keep promoting on this thread, so thanks for your help, but I'll just keep limping along with my system the way it is. I will also never directly reply to any of your statements that might include me in the future because it would be a waste of my time. When Paul wrote that one possible position, that is quite rational, " that passives can sometimes be better than actives" a few posts ago I was in total agreement with one qualifier besides system synergy is personal taste. Yet, good old George tells me that I have a bad match and who am I to know better then him how my own system sounds. George you have convinced me, I have changed my mind I will sell off my CF-080 as soon as possible and either call or E-mail you with my order for your LSA masterpiece. |
You do have a bad match Teayjay with or without the use of the Bryston Xover, and what it shows is that when you said you tried the Lightspeed Attenuator you also put it into that same bad impedance matching situation. With or without the Bryston xover, the Lightspeed saw the 20k input of the Passlabs XA60.5 or it saw the 15k input of the Bryston xover, and your $60k preamp is in the same unfortunate mismatch. It is well documented that the Lightspeed Attenuator needs to see 47k or more load, and your preamp is even higher at 100k. You your self said you do not care or know about impedance matching components, yet you think you have cred by just throwing money at components and bagging them if they don't sound right. |
George, it just does not seem possible that there is a preamp on the market with 33kohm Zout - does it? It would be almost impossible to match with most any amp. Unfortunately, their website does not provide a Zout for the preamp, but as a hybrid design, you have to believe they are doing something to provide buffering for that 12au7. But anyway, clearly you and Terry will never be in agreement, no matter what the Zs say in or out - I think we can all agree on that. It does seem that the passive / active divide is even more divisive than tubes / SS:) I wonder why. |
Try to bear with me here and let it sink in. You see this impedance matching goes right through the whole system between components. EG: source to preamp, preamp to poweramp, and poweramp to speakers. Even the internal stages of the individual components should be impedance matched if the designer is worth his salt. eg: of a poweramp it's: input stage to voltage stage, voltage stage to driver stage, driver stage to output stage. Same for goes the pre and source. Hopefully they are done/designed right as the end user cannot do anything about these stages inside the individual components or check them. But at least the end user can make sure the components are themselves matched from each other. I specify with the Lightspeed Attenuator that it needs to see a poweramp with 47k or higher input impedance, I believe that tube preamp and tube dac/cdp manufacturers should be saying the same, this is why so many high output impedance tube pre's sound bad when they are mated to low impedance poweramps. Cheers George |
Paul one of the tube guru's on diyaudio said the solid state part is at the input, and it's even stated that the 12AU7 in cascode mode is directly attached to the rca outputs in the manufacturers blurbs on a website. I asked what other preamps used this cascode output stage, and he said Rouge Audio used to on their preamps but their poweramps are very high, the M120 monoblocks I had here were 1meg! input impedance. And also he said some early Lamm preamps were also cascode output. It is ok to have this high output impedance if you have over 100k or more on the poweramps, but you do get the problem of having to use low capacitance and short interconnects 1.5mt or less, just like with the Lightspeed. Cheers George |
33k ohm output impedance is rather high, especially given that the Concert Fidelity amps have an input impedance of 47k ohms. Is that 33k ohm constant or at a specific frequency or perhaps a range? Now I know Masa Tsuda personally and have been working the Concert Fidelity rooms at the last few CES/RMAF shows. I'm here to tell you Masa in my opinion is a great designer and the system of components he brings to the shows has incredible synergy and sound. I'm having a hard time getting my hands around this so I'm going to go straight to the source and find out more information. |
This is the output description "The 12AU7 tubes are on the back panel virtually bonded to the output connectors." This is where the solid state part is used "It uses a solid-state analogue switch for input switching and an analogue solid-state volume control selected for its sonic quality and tracking accuracy." All this can be read here, half way down. http://www.positive-feedback.com/Issue41/concert_fidelity.htm Cheers George |
George, yes I saw that review and was aware of the other information. As I stated in my previous post, amps input impedance is 47k ohms. What I am having a difficult time with is why the designer would build a preamp circuit with 33k ohm output impedance (assuming this is accurate) to mate with amps that have not much more relative to input impedance. It makes little sense given I have spent approximately 150 hours or so listening to this system and it in no way sounds like a bad match to me. |
Like I have always said Tony, it will work and sound ok with no damaging side effects. But the source should be at least 3 x or more lower output impedance than the the load. I imagine then it could have sounded even better. Now can you imagine what Teajay heard when he listened to the Lightspeed into a 15k load and drew his conclusions? Cheers George |
George, I'm not sure that Teajay's "LSA test" was with his own system, it might have be a group of audiophiles getting together, comparing notes - obviously testing the LSA with Pass gear would be far from optimal, like testing a 3 watt SET with a pair of Maggies - no way to fairly assess either the amp or speakers in that situation. Anthony, it will be interested to hear what Tsuda has to say, something does not seem right. |
Just ran into this thread. Seems another LDR attenuator has been making the rounds as a DIY kit. There is a balanced version available as well. Not sure technology wise what the differences are with the LSA, but thought some of you here might be curious to read about it anyway: http://www.diyaudio.com/forums/vendors-bazaar/176847-warpspeed-optocoupler-volume-control.html |
I just received the October issue of Stereophile. Please read Sam's Space as I swear I could have written that piece! He does a nice job explaining why some like actives in his well written and balanced article on preamps. Nice job Sam! I could not possibly agree more or have said it more simply than Sam. He is not saying one is better, but just gives another perspective to consider. Yes, ALL devices (active & passive preamps) have a sound and they all impact a total system's sound. Pick the one that suites your fancy and sounds most like music to you. Great piece IMHO. |
I agree with Sam, when you need gain or have an impedance mismatch and long cables you need an active line stage, and I imagine when you need an active it is pretty obvious when comparing it to a passive. I agree that ultimately one must choose what fits their fancy, especially since it is "reproduction" we are talking about. When you need an active, a passive will not do. What we cannot do without is a great preamp, in whatever form is most suitable to our source/amp/cabling. |
Yes I too received it today, and I need to tell all, before any assumptions are made, that Sam Tellig (Tom) purchased one at full price over 2 years ago, before I had any idea that he was going to review it. And just a couple of weeks ago one was sent off to a classical guitar buff, in New York, his son David, again at full price. Cheers George |
Pubul57 Agreed, Sam did not NEED and active, but WANTED one. He does not NEED the CJ Art pre, but would like/wanted one! No NEED for an active in terms of function many times, however some desire one for the resulting sound benefit they perceive in their system. This is a want, not need in many cases. |
I agree, there is nothing wrong with folks liking coloration that please them. I would just say that on principle, I would want my preamp to offer as little as possible so I can use it with alot of different amps and speakers with different voices - that is, the more nuetral the preamp the more equipment it can work with sonically. That is just a philosophical decision and preference on my part. Interesting that Sam paid full price and then decided to get an LSA for his son. Not sure about Sam's wants, but he does NEED to be excited about new products if he wants to keep writing:) |
Jdec, it may or may not be. Remember, the end sound from your speakers is the sum total of all the parts in the system. Every single footer, wire etc...has impact. No two systems will ever sound identical and the end result may or may not have more added coloration then another system. Like Sam said sometimes an active just helps a system sound more like natural music with wonderful tone and ease. Sometimes a passive does this also. More than one road to accurate music and a passive is not the ONLY road to this end. All systems and gear have a sonic personality within a given system - all gear with no exceptions. |
