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#82
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#83
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#84
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B&D wrote:
On 10/24/04 11:19 AM, in article , "Robert C. Lang" wrote: How about something being "wrong" with the Audible Illusions? Or how about nothing being wrong with the Audible Illusions but it just innocently rolled off below 30 hz? Because, roll off notwithstanding the 3A did sound good. And if something is "wrong" with my system you care to offer your opinion as to what are the possibilities? Particularly, since the problem (lack of below 30 hz bass) has not been audibly evident with other line stages. Either the spec is incorrect, or there is abuild defect in the AI unit - like a series capacitor between stages or after the last stage has a value that might be too high - or that the output series capacitor is driving the equivalent of a shunt inductor in your system which would tune the high pass response? Uhh, if the series capacitor has too high a value, it will give an even *lower* -3dB frequency. A coupling capacitor at the output that is too low can explain what was observed, assuming the observations were accurate. It would take a very incompetent engineer to pick the wrong value, though. BTW, I know of no crossover network or amplifier that has a shunt inductor at the input sufficiently high to affect the bass response. Assuming a coupling cap of 10 uF. It will take a shunt inductor of 6.33 henries (!) to resonate at 20 Hz. |
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#85
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B&D wrote:
On 10/24/04 11:22 AM, in article , "Stewart Pinkerton" wrote: But the question wasn't whether a CD could capture the dynamic range of an extant master tape, but whether it could capture the dynamic range of a live performance. Let me rephrase that. Modern 24-bit digital mastering has a true dynamic range of around 110dB, but even the most dynamic studio recordings do not exceed 80dB at the very most. I'm not aware of any live concert recording which exceeds 70dB, because while the peak SPLs in the front stalls may reach 105-110dB for the grandest symphonic works, the noise floor in the hall is never less than 40dB, even in that moment of relative hush when the conductor first raises his baton. This is a bit off topic, but wanted to ask the group: Interesting thing - I talked with someone who was talking about periodic signals vs. true white noise - people can detect a periodic signal a bit into the absolute noise floor (kind of like how you can "hear" a morse code feed even though it is a bit below the noise floor, but not be able to make out the tone itself). A tone can be detected even if it's below the noise floor. You can do enough averaging (filtering) to recover it. I am speculating here - but would the type of noise floor matter in the general niceness of the sound itself? For instance, if I put a square wave or triangle wave at 40dB below the peak of an orchestra, and the followed it up with white noise at the same rms power level - would one sound better than the other? Well, what do you think? In one case you have a tone, and in the other you have white noise. You want to always hear a tone when you music is playing? It occurred to me when I was listening to a Susan McCorkle CD when she sings "The Waters of March" and the percussionist uses the brush on the cymbal making the very white noise-like background - which is pleasant when one is listening to a voice. |
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#86
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#87
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Stewart Pinkerton wrote:
On 17 Oct 2004 16:55:58 GMT, (Bob Ross) wrote: Stewart Pinkerton wrote in message ... On 15 Oct 2004 03:30:40 GMT, B&D wrote: I have a question - given the dynamic range of live music (I have no idea what that might be) - is it possible to record it faithfully on CD or other media without at least some compression? Yes. There is no known master tape with a dynamic range of greater than 80-85 dB But the question wasn't whether a CD could capture the dynamic range of an extant master tape, but whether it could capture the dynamic range of a live performance. Let me rephrase that. Modern 24-bit digital mastering has a true dynamic range of around 110dB, but even the most dynamic studio recordings do not exceed 80dB at the very most. I'm not aware of any live concert recording which exceeds 70dB, because while the peak SPLs in the front stalls may reach 105-110dB for the grandest symphonic works, the noise floor in the hall is never less than 40dB, even in that moment of relative hush when the conductor first raises his baton. In fact, most live performances will have a dynamic range of about 60-70dB, as the noise floor in a concert hall will never be lower than 40dB or so. You've never heard music beneath the noise floor in a recording? Or beneath the noise floor in a concert hall? Sure, and you can do exactly the same with CD. I've recorded tones at -110dB on a CD-R which were clearly audible. That's what dithering *does*, but it does not affect the definition of dynamic range, which is from peak level to broadband noise floor. Yes, given the dynamic range of MOST live music, 16 bit/44.1k PCM is an adequate recording medium. No, *all* live music. And those very few exceptions would probably be pointless to attempt to store in any medium that exceeds redbook CD's dynamic range because they would tax the limitations of the playback equipment...or of the listener's ears. AFAIK, there are no such exceptions - unless you can produce a recording of such an event. Everest's 'Fundamentals of Acoustics' retains in its current (4th ) edition a figure from previous editions, (Fig 5-12 in the 4th) derived from a 1982 study by Fiedler of the dynamic range of live 'classical' concert music. This shows a maximum range of 118dB for close-mic'd percussive symphonic music, and 113 dB for typical symphonic music without an audience (micing conditions not stated, but presumably not close-mic'd). Everest describes the this as follows: "Fiedler's study has shown that a dynamic range of up to 118dB is necessary for subjectively noise-free reproduction of music. He considered the peak instantaneous sound level of various sources ... and the just-audible threshold for white noise added to the program source whent he listener is in the normal listening situation. He used musical perforamcnes of high peak levesl in ta quiet environment and a very simple recording setup. ....the signal to noise ration offered by a16-bit PCM system is shown to be inadequate for all but piano solo. Future developments will undoubtedly require greater dynamic range than that offered by 16-bit digita;l systems.' So, leaving aside the prevalence of 16-bit recording setups these days, has Everest misinterpreted Fiedler's data or is there another dimension to the story? (Fiedler LD . 1982. Dynamic range requirements for subjectively noise-free reproduction of music . J Aud Eng Soc, 30:, 7/8, 504-511.) |
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#88
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Stewart Pinkerton wrote in message ...
On 24 Oct 2004 15:19:50 GMT, (Robert C. Lang) wrote: Stewart Pinkerton wrote in message ... On 23 Oct 2004 14:48:28 GMT, (Robert C. Lang) wrote: Agreed. But also that even competently designed gear such as the Audible Illusion 3A is not always a fit in all systems. However, what you report is simply not technically possible. So that I may further understand what you are talking about, what *specifically* is not technically possible? That high-capacitance cables, or low load impedance, could affect the bass. Agreed. Robert C. Lang |
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#89
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(Robert C. Lang) wrote:
(Nousaine) wrote in message ... (Robert C. Lang) wrote: Chung wrote in message ... Robert C. Lang wrote: Stewart Pinkerton wrote in message ... . But your conclusions raises more questions (for me) they answer. If there are no practical or measurable quality differences among resistors what makes some passive sound better than others (and that indeed has been my experience)? Has it indeed? Do you have any *evidence* for this extraordinary claim? Please see comments in my post to this thread dated October 12 relative to my experiences with the Audible Illusions 3A. What you posted was a sighted preference, hardly evidence. If you can show that the Audible Illusions 3A has *measureably* better performance, then you have something to start from. Even then, the better performance could be due to better choice of resistor values, or a host of other possibilities like better matching, better switching, etc., rather than using expensive resistors vs not-so-expensive resistors I may be wrong but I *think* Stewart was questioning whether I had evidence that I found some line stages to sound better or different than other line stages, irrespective of the resistor issue. Because a few posts ago after you and Stewart both presented compelling empirical info about resistor measurements and performance I conceded on that issue. That is, based on information presented there is no basis to suggest that one resistor, no matter what the cost, will perform or sound any different than another resistor. That the Audible Illusions 3A sounded and performed "differently" in my system than other line stages sounded and performed in my system is a different matter altogether (I think). The question asked in the thread is "Do all preamps sound alike"? It has been my experience, that in my system. they don't all sound alike. You suggest that because my audition of the Audible Illusion 3A was sighted that my observations were not valid. (By the way, the performance of the 3A was "less" not "better" in my system than other line stages). I believe that if you read my comments closely that you will find that the fact it was sighted had no affect on my observation. I realize this is what they all say. But here it was graphically black and white. No blind test required. Literally hundreds of times I have listened to the Telarc Michael Murray performance of the Poulenc Organ Concerto. Heading into the final 3 minutes or so the recording (and at a live performance) I habitually brace myself for a faint but *very* deep organ passage which is sustained continuously for well over 90 seconds. Because it is sustained it is easier to gauge than a transient. Telarc says that this sustained note was at 23 HZ. It feels like a small earthquake (I live in the San Francisco Bay Area). But with the Audible Illusions that sustained note simply did not occur. It simply didn't happen. The faint groan of the organ didn't happen, the *seemingly* change in the barometric pressure (for lack of a better description) didn't happen, the very unique and easily identifiable flutter of the floor didn't happen. Turning up the volume to higher than normal did not make it happen. The bottom octave was clearly rolled off. I can't speak to *why* the lower octave was not reproduced. I offer some opinions in my original comments and both the dealer and the manufacturer confirmed that the unit was working to spec. Perhaps you can shed some additional light on that. I can only say to an absolute certainty that in *my* system (and that's all I am talking about) that the lower octave was lacking with the 3A whereas as with most others line stages it was not an issue. Up until that time I thought that speakers were the limiting factor and that all pre amps sounded a like (if not identical). I learned from that experience that other parts of the chain can also get in the way. Robert C. Lang If what you say is true than wouldn't you agree that these differences would be completely revealed with a frequency response measurement taken at the input terminals of the loudspeakers? Or even at the inputs to the power amplifier? As pronounced as the bass frequency roll off was I would think it would be readily measurable. If I suggested otherwise I certainly didn't mean to. As humans we can ONLY hear level differences (sound pressure) and arrival time differences between our 2 ears. I'm wondering exactly how pre-amplifiers manage to alter either when they are in a bypass mode. I don't know. Keep in mind that my observation of the bass roll off did not involve transients that in music can be tricky, at best, to compare lest you use a level matched A/B switch of some sort. On the contrary the difference I observed were an organ bass note that was sustained, continuously for 90 seconds. With the Audible Illusions that 23 HZ note was completely missing for the entire 90 seconds. I can only logically conclude that the Audible Illusions, in my system, rolled off sharply below 30 HZ. What do you think acounts for such audible, tactile (floor vibrations that did not occur as with other line stages), and visual (lack of room vibrations as there are with other line stages) differences? Robert C. Lang Poor design or ineffective operation. IOW it uses a high pass filter at an unacceptably high frequency or it was broke. |
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#90
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On 24 Oct 2004 17:31:37 GMT, "normanstrong"
wrote: "Stewart Pinkerton" wrote in message ... On 23 Oct 2004 14:45:38 GMT, (Robert C. Lang) wrote: I can only logically conclude that the Audible Illusions, in my system, rolled off sharply below 30 HZ. What do you think acounts for such audible, tactile (floor vibrations that did not occur as with other line stages), and visual (lack of room vibrations as there are with other line stages) differences? What you report is shall we say, vanishingly unlikely, unless there was something *seriously* wrong with your system. Bear in mind that the 3A is specified as flat to -1dB down to 2Hz, and you'll see that what you are reporting is essentially impossible. BTW, it's worth remembering that, while John Curl is a talented and professional designer, Art Ferris is a graphic artist turned 'high end' audio salesman, so not to be relied on for anything technical! :-) I gather that this is a passive "preamp". If so, it should not have a low frequency limit--unless there is a coupling capacitor somewhere in the circuit. If this capacitor is at the input, I can see no way that it can screw up the low frequency response, since the load impedance is known by the manufacturer. However, if it's at the output, the load is unknown, and if you have several parallel loads, it could move the pole up to where 23 Hz is down quite a bit. IMHO this would be a bad design choice, but stranger things have happened. Actually, it's an active tubed unit, but specified as flat to 2Hz, and measured as flat to below 10Hz by Stereophile. You might try disconnecting as many devices as you can, and then see if the bass improves. Of course if you have a voltmeter and a stable frequency source, you can answer the question at once. But according to the OP, he uses an active crossover, so he does *not* have a low load on this preamp. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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#91
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On 24 Oct 2004 18:20:06 GMT, B&D wrote:
On 10/24/04 11:22 AM, in article , "Stewart Pinkerton" wrote: But the question wasn't whether a CD could capture the dynamic range of an extant master tape, but whether it could capture the dynamic range of a live performance. Let me rephrase that. Modern 24-bit digital mastering has a true dynamic range of around 110dB, but even the most dynamic studio recordings do not exceed 80dB at the very most. I'm not aware of any live concert recording which exceeds 70dB, because while the peak SPLs in the front stalls may reach 105-110dB for the grandest symphonic works, the noise floor in the hall is never less than 40dB, even in that moment of relative hush when the conductor first raises his baton. This is a bit off topic, but wanted to ask the group: Interesting thing - I talked with someone who was talking about periodic signals vs. true white noise - people can detect a periodic signal a bit into the absolute noise floor (kind of like how you can "hear" a morse code feed even though it is a bit below the noise floor, but not be able to make out the tone itself). I am speculating here - but would the type of noise floor matter in the general niceness of the sound itself? For instance, if I put a square wave or triangle wave at 40dB below the peak of an orchestra, and the followed it up with white noise at the same rms power level - would one sound better than the other? It occurred to me when I was listening to a Susan McCorkle CD when she sings "The Waters of March" and the percussionist uses the brush on the cymbal making the very white noise-like background - which is pleasant when one is listening to a voice. It has often been suggested that such a background mask is one of the reasons why some listeners prefer vinyl to CD, and also why some recording engineers prefer hissy analogue tape to the inky blackness of digital. -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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#92
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Stewart Pinkerton wrote in message ...
On 24 Oct 2004 15:16:37 GMT, (Robert C. Lang) wrote: Literally hundreds of times I have listened to the Telarc Michael Murray performance of the Poulenc Organ Concerto. Heading into the final 3 minutes or so the recording (and at a live performance) I habitually brace myself for a faint but *very* deep organ passage which is sustained continuously for well over 90 seconds. Because it is sustained it is easier to gauge than a transient. Telarc says that this sustained note was at 23 HZ. It feels like a small earthquake (I live in the San Francisco Bay Area). But with the Audible Illusions that sustained note simply did not occur. It simply didn't happen. The faint groan of the organ didn't happen, the *seemingly* change in the barometric pressure (for lack of a better description) didn't happen, the very unique and easily identifiable flutter of the floor didn't happen. Turning up the volume to higher than normal did not make it happen. The bottom octave was clearly rolled off. That may of course be literally true. Have you measured the frequency response of this generally well-regarded preamp? First, it doesn't matter. Audible Illusions (including at least two engineers in the company) found my observations to be dispassionate and plausible not to require measurements or dbts to confirm the obvious. Audible Illusions (only 20 minutes away) had the opportunity to make measurements; they chose not to. They came to the same conclusions I did. That is, that there *was* an audible bass roll off of the 3A in *my* system (not necessarily applicable to your system). They sound like classic 'high end' clowns with no technical expertise (or indeed *interest*) whatever. Did they not *care* that a purchaser was supposedly experiencing severe difficulties with their equipment? Second, with respect to your remarkable propensity to curtly dismiss others opinions and require corroborative proof for such, by English definition *opinion* "is a belief or conclusion held with confidence, but not substantiated by positive knowledge or proof". Opinions are by *definition* unsubstantiated! This definition should be familiar to you because I have offered to you on several occasions in the past. So, you admit that this 'lack of bass' is simply an opinion, and need not have any substance in the real physical world? You may refer to it as "simply an opinion" if you like. While certainly not infallible, I believe my opinion to be well-founded based on pertinent observations and facts that do include "real physical world" phenomena. As I said before "with the Audible Illusions faint groan of the organ didn't happen, the *seemingly* change in the barometric pressure (for lack of a better description) didn't happen, the very unique and easily identifiable flutter of the floor (physical world and a fact) didn't happen. The lamp vibration (physical world and a fact) did not occur. Turning up the volume to higher than normal did not make it happen. Yesterday you said, "That may of course be literally true". Now today you say, without even so much of a modicum of explanation for your reversal, "Your imagination seems to be the most likely culprit". In addition, my opinion of roll off of bass below 30 hz in *my* system was backed with the unanimity of two engineers and Mr. Ferris at Audible Illusions. Yesterday you referred to the Audible Illusions 3A as "generally well regarded preamp" Today you say of key Audible Illusion employees "They sound like classic 'high end' clowns with no technical expertise Ø (or indeed *interest*) whatever. You clearly have nothing relevant or pertinent to add to this issue. In addition, you have sunk to retaliating with remarks that are deliberately inappropriate and offensively discourteous. What a waste. You have clearly lost your way and should move on. Robert C. Lang Second, with respect to your remarkable propensity to curtly dismiss others opinions and require corroborative proof for such, by English definition *opinion* "is a belief or conclusion held with confidence, but not substantiated by positive knowledge or proof". Opinions are by *definition* unsubstantiated! This definition should be familiar to you because I have offered to you on several occasions in the past. So, you admit that this 'lack of bass' is simply an opinion, and need not have any substance in the real physical world? I have never asked you to substantiate with measurements or with any other form of "evidence" your *opinion* on XRCDs or CD players, speakers, or anything else. It would be not only disingenious, but also unfair to you and to the discussion. Not at all, I am always happy to explain my preferences. Indeed, at times your pronouncements are validated only by the fervor with which you offer them. For example, this past January 21 I mentioned to the group (not you in particular) that I was considering several universal players. You exhorted "Pioneer DV-868 - accept no substitute!" At the moment, I hold the same opinion. The exchange went like this: I'm attending CES specifically to narrow my choices for a universal player so I can listen to DVD-A as well as SACD and CD. Pioneer DV-868 - accept no substitute! :-) And then when I asked for even a low-level clarification on one of your endorsements you didn't respond. No problem there, but I would hope that you would refrain from holding others to standards that you yourself don't adhere to. Excuse me? What 'clarification' did you request? I am always happy to explain my 'endorsements'. Perhaps you phrased your request oddly - Ø quelle surprise......................... |
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#93
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Chung wrote in message ...
Robert C. Lang wrote: Chung wrote in message I would guess that perhaps that unit has a much lower input resistance, and that caused the output capacitance of the source to have a high-pass cut-off that is too high in frequency. Or that it has a coupling capacitor that is too small. Is there transformer coupling inside the unit? Do you have a schematic of the 3A? On the manufacturer's website, the specs for the M3A say that the error is +/- 1dB from 2 Hz to 100KHz for the high-level input. So that clearly does not agree with what you observed. Were you using the phono section? No. My observation was based primarily on the Telarc Poulenc Organ Concerto CD. In that case, there is a huge discrepancy between your observations and the spec sheet. I believe there has been an assumption among many of us, myself included, that the manufacturer's published specifications are accurate and unquestioned. Is this something we can count on? Are manufacturers specifications routinely independently verified? I do believe that it is not uncommon that when a magazine measure's gear that they are testing that one or more of the manufacturer's specs are not met. And these are units that are *hand picked* by the manufacturer. It seems that it is not uncommon for an amp, for example, not to meet it's power ratings into 4 ohms and below, headroom measurements can fall short, input sensitivity and impedance levels don't measure up to what the claims are, etc. These don't necessarily effect negative effect the performance of the gear, I guess. Like wise, if the manufacturer says the frequency response of said gear is flat 5HZ to 50khz but it really falls of at 25hz 99.8% (guestimate) of users would not detect the shortfall. I attempted (during the course of this thread) tried to find some independent measurements done of the 3A. So far I have not been successful. What you described can also be easily measured, if it was the high-level input that you were using. In fact, you can probably measure it yourself using a good voltmeter, if you have access to that unit. Play a test CD disc with constant-level low frequency tones, and see how the output level varies as you play different tones. It should be flat down to at least 20 Hz. Make sure that you connect the outputs of the preamp to the power amp while you make that measurement. At my invitation Audible Illusion had every opportunity to make measurements, while the pre amp was in my system as they are only 20 minutes away. They did not think it was necessary based on my observations. By the way, the representatives of Audible Illusions never doubted the validity of my observations (I have only used the word "observation", never "evidence". Because as clearly stated in my original comments (the ones made in February 2000 at http://www.audioreview.com/Preamplifiers/Audible Illusions/PRD_118448_1591crx.aspx#reviews) I had a strong bias in favor of Audible Illusion because it is a local company and I had been in direct contact with the company to arrange a purchase. Audible Illusions took my observations and comments quite seriously and were never cynical. They found my observations to be quite compelling (and said so) because they involved more that just hearing (they also involved sight [lamps not vibrating] and feel [vibration of floor]. Audible Illusions offered an explanation that I retrieved from the archives of this group I made several years back. How could they have taken your comments seriously if they did not try to get to the cause of the problem? Or give you a replacement first? Audible Illusions did check out the specific unit, a dealer loaner, that I used and declared it a fully working unit. Also, I had several lengthy conversations with several people at the company. Beyond that I can't respond to your question. To put the Audible Illusion representative's comments in perspective it should be noted that my system is bi-amped. "The day after I wrote my comments Art Ferris, of Audible Illusions, in a email to me expressed his belief that because I was "driving several amplifiers, electronic crossover etc." he believed that the "paralleled load impedance" of my amplifiers was well below the minimum load impedance of 20kohm. I would think that your electronic crossover is in *series* with the power amp, so that the preamp only sees the crossover as a load. Does your crossover has an extremely low input impedance, like less than 10K? I just looked up the spec in the last published Audio Equipment Guide (October 1999). The input impedance is listed at 50K ohms. For what it's worth I see several listed with input impedances at 10k or less (as low as 4). Mr. Ferris also expressed concern whether I was "running low capacitance interconnect recommended for use with the Audible Illusion 3A. He expressed that high capacitance interconnects could account for bass roll-off. Mr. Ferris is clearly technically incompetent. You can ignore everything he said, based on that comment. Mr. Ferriss also stated that "in most normal systems", where the pre amp is driving an amplifier with an input impedance above 20kohm, I would not experience a problem." Assuming that the +/- 1dB spec at 2Hz is achieved at 50K loading as stated in the specs, it would take a load of 5K to move the -1dB point to 20 Hz, if the output coupling capacitor was causing the roll-off. (If some interstage cap or transformer was casuing the roll-off, then output loading should not make any difference.) And even that still does not account for your observations, which were more like -6dB or worse at 23 Hz. Seems like you had a defective M3A. That was my thinking initially. As stated above Audible Illusions did check out the specific unit and said it was fine. Also, to the ear, the unit sounded very good, except for the very botoom octave. Of course, it could have measured terribly, but Audible Illusions said it was OK. Robert C. Lang |
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#94
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I want to make a brief amendment to my last reply to Bob Marcus. I
said, in part, about the Audible Illusions 3A that: "It is still a superb line stage that I strongly recommend, if you don't have speakers that reach to the lower octave and/or you don't listen to organ music that may reach that low". My caveat should be deleted and rephrased to say that if an audiophile is so inclined he or she should audition the 3A in their system irrespective of how low their speakers go or what music they listen to, because their experiences, particularly in the lowest audible octave, could be different than mine. Robert C. Lang |
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#95
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(Bob Marcus) wrote in message ...
(Robert C. Lang) wrote in message ... Just for the record, no one's ever claimed that all preamps sound alike. Perhaps we should be open to the possibility that this is NOT competently designed gear. We should certainly be open to the possibility that this was defective gear. And we certainly cannot conclude from your experience that preamps will in general sound different (barring defects or incompetent design). bob Or that I made an error somewhere along the line during hook up or something. Having said that it is my opinion that any given component can peform and sound differently in a given system. I believe my experience with the Audible Illusions 3A lends credence to that opinion. But I also have found that, in my limited experience, most gear in my system sounds *very* similar and probably in most situations identical. There have been periodic exceptions such as with the Audible Illusions. But even then that line stage sounded very similar (but I don't believe identical) to the other 4 line stages I auditioned in my system during that period. The only pronounced difference was in the *extreme* bottom where, for whatever reasons, whether it was due to a defect, design limitation, an error on my part, or whatever, it seemed to roll off. I still find it to be a damn good sounding line stage in my opinion. It is still a superb line stage that I strongly recommend, if you don't have speakers that reach to the lower octave and/or you don't listen to organ music that may reach that low. If I were looking for a two-channel line stage today I believe, based on the input provided during this thread (although some of it was expressed in a manner that was unnecessarily harsh), I would give the 3A another shot and bring some aspects of what I have learned here to the audition. Because I do agree that things don't add up. That's obvious. To that degree I regret not applying some measurements, for example, or insisting that Audible Illusions do some since they are so close geographically. I think that it could be fun and revealing. Robert C. Lang |
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#96
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Robert C. Lang wrote:
In addition, my opinion of roll off of bass below 30 hz in *my* system was backed with the unanimity of two engineers and Mr. Ferris at Audible Illusions. Did those people listen to the M3A in *your* system and agreed that the bass was indeed rolled off? Or did they simply agree with you without listening to it, but having made measurements on it? |
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#97
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Robert C. Lang wrote:
Chung wrote in message ... Robert C. Lang wrote: Chung wrote in message I would guess that perhaps that unit has a much lower input resistance, and that caused the output capacitance of the source to have a high-pass cut-off that is too high in frequency. Or that it has a coupling capacitor that is too small. Is there transformer coupling inside the unit? Do you have a schematic of the 3A? On the manufacturer's website, the specs for the M3A say that the error is +/- 1dB from 2 Hz to 100KHz for the high-level input. So that clearly does not agree with what you observed. Were you using the phono section? No. My observation was based primarily on the Telarc Poulenc Organ Concerto CD. In that case, there is a huge discrepancy between your observations and the spec sheet. I believe there has been an assumption among many of us, myself included, that the manufacturer's published specifications are accurate and unquestioned. Is this something we can count on? Are manufacturers specifications routinely independently verified? Well, we have certainly seen published specs that do not agree with measurements. However, it is trivially easy to make a preamp that does not roll off 23 Hz. I may believe that the flatness spec does not extend to 2Hz, but I would be shocked to find that it only extends to 30 Hz or so. That's more than a decade off! Or about 4 octaves! I do believe that it is not uncommon that when a magazine measure's gear that they are testing that one or more of the manufacturer's specs are not met. And these are units that are *hand picked* by the manufacturer. It seems that it is not uncommon for an amp, for example, not to meet it's power ratings into 4 ohms and below, headroom measurements can fall short, input sensitivity and impedance levels don't measure up to what the claims are, etc. These don't necessarily effect negative effect the performance of the gear, I guess. Like wise, if the manufacturer says the frequency response of said gear is flat 5HZ to 50khz but it really falls of at 25hz 99.8% (guestimate) of users would not detect the shortfall. In that case, the product is simply defective, if it's supposed to be flat to 5Hz and measures flat only to 25Hz. It makes you wonder what kind of QA the manufacturer has. You have to understand that the flatness spec is dictated by passive components like capacitors where it is common to obtain +/- 10% tolerances. Which means the -3dB frequency should only be off by about 10%, not a factor of 10. I attempted (during the course of this thread) tried to find some independent measurements done of the 3A. So far I have not been successful. What you described can also be easily measured, if it was the high-level input that you were using. In fact, you can probably measure it yourself using a good voltmeter, if you have access to that unit. Play a test CD disc with constant-level low frequency tones, and see how the output level varies as you play different tones. It should be flat down to at least 20 Hz. Make sure that you connect the outputs of the preamp to the power amp while you make that measurement. At my invitation Audible Illusion had every opportunity to make measurements, while the pre amp was in my system as they are only 20 minutes away. They did not think it was necessary based on my observations. By the way, the representatives of Audible Illusions never doubted the validity of my observations (I have only used the word "observation", never "evidence". Because as clearly stated in my original comments (the ones made in February 2000 at http://www.audioreview.com/Preamplifiers/Audible Illusions/PRD_118448_1591crx.aspx#reviews) I had a strong bias in favor of Audible Illusion because it is a local company and I had been in direct contact with the company to arrange a purchase. Audible Illusions took my observations and comments quite seriously and were never cynical. They found my observations to be quite compelling (and said so) because they involved more that just hearing (they also involved sight [lamps not vibrating] and feel [vibration of floor]. Audible Illusions offered an explanation that I retrieved from the archives of this group I made several years back. How could they have taken your comments seriously if they did not try to get to the cause of the problem? Or give you a replacement first? Audible Illusions did check out the specific unit, a dealer loaner, that I used and declared it a fully working unit. So it measures flat (-1dB) to 2Hz. Which makes one wonder why they accepted your observations at full face value. Also, I had several lengthy conversations with several people at the company. Beyond that I can't respond to your question. To put the Audible Illusion representative's comments in perspective it should be noted that my system is bi-amped. "The day after I wrote my comments Art Ferris, of Audible Illusions, in a email to me expressed his belief that because I was "driving several amplifiers, electronic crossover etc." he believed that the "paralleled load impedance" of my amplifiers was well below the minimum load impedance of 20kohm. I would think that your electronic crossover is in *series* with the power amp, so that the preamp only sees the crossover as a load. Does your crossover has an extremely low input impedance, like less than 10K? I just looked up the spec in the last published Audio Equipment Guide (October 1999). The input impedance is listed at 50K ohms. For what it's worth I see several listed with input impedances at 10k or less (as low as 4). If the spec'd impedance is 50K and it measures 10K or less, it's broken. You think your crossover is broken? Except if it's broken, wouldn't other preamps have the same problem driving it? Mr. Ferris also expressed concern whether I was "running low capacitance interconnect recommended for use with the Audible Illusion 3A. He expressed that high capacitance interconnects could account for bass roll-off. Mr. Ferris is clearly technically incompetent. You can ignore everything he said, based on that comment. Mr. Ferriss also stated that "in most normal systems", where the pre amp is driving an amplifier with an input impedance above 20kohm, I would not experience a problem." Assuming that the +/- 1dB spec at 2Hz is achieved at 50K loading as stated in the specs, it would take a load of 5K to move the -1dB point to 20 Hz, if the output coupling capacitor was causing the roll-off. (If some interstage cap or transformer was casuing the roll-off, then output loading should not make any difference.) And even that still does not account for your observations, which were more like -6dB or worse at 23 Hz. Seems like you had a defective M3A. That was my thinking initially. As stated above Audible Illusions did check out the specific unit and said it was fine. Also, to the ear, the unit sounded very good, except for the very botoom octave. Of course, it could have measured terribly, but Audible Illusions said it was OK. Robert C. Lang |
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On 26 Oct 2004 00:01:07 GMT, Steven Sullivan wrote:
Stewart Pinkerton wrote: On 17 Oct 2004 16:55:58 GMT, (Bob Ross) wrote: Stewart Pinkerton wrote in message ... On 15 Oct 2004 03:30:40 GMT, B&D wrote: I have a question - given the dynamic range of live music (I have no idea what that might be) - is it possible to record it faithfully on CD or other media without at least some compression? Yes. There is no known master tape with a dynamic range of greater than 80-85 dB But the question wasn't whether a CD could capture the dynamic range of an extant master tape, but whether it could capture the dynamic range of a live performance. Let me rephrase that. Modern 24-bit digital mastering has a true dynamic range of around 110dB, but even the most dynamic studio recordings do not exceed 80dB at the very most. I'm not aware of any live concert recording which exceeds 70dB, because while the peak SPLs in the front stalls may reach 105-110dB for the grandest symphonic works, the noise floor in the hall is never less than 40dB, even in that moment of relative hush when the conductor first raises his baton. In fact, most live performances will have a dynamic range of about 60-70dB, as the noise floor in a concert hall will never be lower than 40dB or so. You've never heard music beneath the noise floor in a recording? Or beneath the noise floor in a concert hall? Sure, and you can do exactly the same with CD. I've recorded tones at -110dB on a CD-R which were clearly audible. That's what dithering *does*, but it does not affect the definition of dynamic range, which is from peak level to broadband noise floor. Yes, given the dynamic range of MOST live music, 16 bit/44.1k PCM is an adequate recording medium. No, *all* live music. And those very few exceptions would probably be pointless to attempt to store in any medium that exceeds redbook CD's dynamic range because they would tax the limitations of the playback equipment...or of the listener's ears. AFAIK, there are no such exceptions - unless you can produce a recording of such an event. Everest's 'Fundamentals of Acoustics' retains in its current (4th ) edition a figure from previous editions, (Fig 5-12 in the 4th) derived from a 1982 study by Fiedler of the dynamic range of live 'classical' concert music. This shows a maximum range of 118dB for close-mic'd percussive symphonic music, and 113 dB for typical symphonic music without an audience (micing conditions not stated, but presumably not close-mic'd). Everest describes the this as follows: "Fiedler's study has shown that a dynamic range of up to 118dB is necessary for subjectively noise-free reproduction of music. He considered the peak instantaneous sound level of various sources ... and the just-audible threshold for white noise added to the program source whent he listener is in the normal listening situation. He used musical perforamcnes of high peak levesl in ta quiet environment and a very simple recording setup. ...the signal to noise ration offered by a16-bit PCM system is shown to be inadequate for all but piano solo. Future developments will undoubtedly require greater dynamic range than that offered by 16-bit digita;l systems.' So, leaving aside the prevalence of 16-bit recording setups these days, has Everest misinterpreted Fiedler's data or is there another dimension to the story? (Fiedler LD . 1982. Dynamic range requirements for subjectively noise-free reproduction of music . J Aud Eng Soc, 30:, 7/8, 504-511.) Oh dear, not the Fiedler fiddle again! It's hard to know whether this was a deliberate distortion by Fiedler, not picked up by Everest, or simply an engineering figure that is being misinterpreted by the reader. Given the convenient claim that 16 bits are inadequate, I tend to suspect the former. However, the following are why this is not a realistic figure to use for determining real-word requirements: 1) The 118dB figure refers to close miking. Note that in many orchestras, the poor players sitting in front of the brass section often use acoustic baffles to prevent hearing damage - and to allow them to hear their own instruments! This is definitely *not* a realistic figure to use, when it is not representative of what any audience member would hear, even from the very front stalls. 2) I believe you'll find that the 113dB figure also refers to close miking, as the difference quoted is simply that between heavily percussive and 'normal' symphonic events. I'm not aware of any figures taken from the usual 'simple miking' position about twelve feet above and behind the conductor, which exceed 110dB peak SPL for any orchestral piece, including Mahler and Wagner. 3) Please note the base measure used for the above - the just-audible threshold of white noise in an otherwise quiet environment. This is 0dB SPL. IOW, what Fieldler is quoting is peak SPLs at one end of the range, and assuming a 'threshold of hearing' bottom limit. This is farcically unrealistic even for a studio recording, where the self-noise of the *microphones* will be above 20dB SPL, and the true wideband noisefloor of the venue will be not less than 30dB. Move to a real reverberant concert hall, where the music will always sound better than an artificially reverb'd studio recording, and the noise floor will jump to a typical 40dB. 3a) Note that when we're back in the real world, that artificial reverb which is *essential* to avoid a studio recording sounding horribly sterile, will in and of itself raise the noise floor by 4-8 dB. 4) Despite the desperate attempts by Fiedler to come up with some reason why we need hi-res replay formats (note that no one denies the usefulness of 24-bits for *recording*, to allow room for accidental mic overloads and EQ), there is no record of *any* real master tape of an acoustic musical event (i.e. no synthesisers) which exceeds 80-85dB dynamic range, and indeed most 'live' classical recordings have more like 60-70dB range. Why therefore does Fiedler claim that we *need* more than 93dB? More importantly, why is he using the utterly unrealistic 0dB SPL as his base reference? -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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On 26 Oct 2004 00:06:37 GMT, (Robert C. Lang)
wrote: Stewart Pinkerton wrote in message ... On 24 Oct 2004 15:16:37 GMT, (Robert C. Lang) wrote: Literally hundreds of times I have listened to the Telarc Michael Murray performance of the Poulenc Organ Concerto. Heading into the final 3 minutes or so the recording (and at a live performance) I habitually brace myself for a faint but *very* deep organ passage which is sustained continuously for well over 90 seconds. Because it is sustained it is easier to gauge than a transient. Telarc says that this sustained note was at 23 HZ. It feels like a small earthquake (I live in the San Francisco Bay Area). But with the Audible Illusions that sustained note simply did not occur. It simply didn't happen. The faint groan of the organ didn't happen, the *seemingly* change in the barometric pressure (for lack of a better description) didn't happen, the very unique and easily identifiable flutter of the floor didn't happen. Turning up the volume to higher than normal did not make it happen. The bottom octave was clearly rolled off. That may of course be literally true. Have you measured the frequency response of this generally well-regarded preamp? First, it doesn't matter. Audible Illusions (including at least two engineers in the company) found my observations to be dispassionate and plausible not to require measurements or dbts to confirm the obvious. Audible Illusions (only 20 minutes away) had the opportunity to make measurements; they chose not to. They came to the same conclusions I did. That is, that there *was* an audible bass roll off of the 3A in *my* system (not necessarily applicable to your system). They sound like classic 'high end' clowns with no technical expertise (or indeed *interest*) whatever. Did they not *care* that a purchaser was supposedly experiencing severe difficulties with their equipment? Second, with respect to your remarkable propensity to curtly dismiss others opinions and require corroborative proof for such, by English definition *opinion* "is a belief or conclusion held with confidence, but not substantiated by positive knowledge or proof". Opinions are by *definition* unsubstantiated! This definition should be familiar to you because I have offered to you on several occasions in the past. So, you admit that this 'lack of bass' is simply an opinion, and need not have any substance in the real physical world? You may refer to it as "simply an opinion" if you like. While certainly not infallible, I believe my opinion to be well-founded based on pertinent observations and facts that do include "real physical world" phenomena. As I said before "with the Audible Illusions faint groan of the organ didn't happen, the *seemingly* change in the barometric pressure (for lack of a better description) didn't happen, the very unique and easily identifiable flutter of the floor (physical world and a fact) didn't happen. The lamp vibration (physical world and a fact) did not occur. Turning up the volume to higher than normal did not make it happen. Yesterday you said, "That may of course be literally true". Now today you say, without even so much of a modicum of explanation for your reversal, "Your imagination seems to be the most likely culprit". There is no 'reversal' in stating that one thing may be true, but another is more likely. In addition, my opinion of roll off of bass below 30 hz in *my* system was backed with the unanimity of two engineers and Mr. Ferris at Audible Illusions. Yesterday you referred to the Audible Illusions 3A as "generally well regarded preamp" Today you say of key Audible Illusion employees "They sound like classic 'high end' clowns with no technical expertise Ø (or indeed *interest*) whatever. The one has, regrettably, nothing to do with the other! :-( You clearly have nothing relevant or pertinent to add to this issue. In addition, you have sunk to retaliating with remarks that are deliberately inappropriate and offensively discourteous. What a waste. You have clearly lost your way and should move on. You seem detemined that your opinion is unchallengeable, and 'you know what you heard'. This is a sadly all too common tale in this forum, and tends to attract skepticism. You have an example of a pre-amplifier which is claimed to be flat to 2Hz, and has been measured flat to less than 10Hz by Stereophile, and yet you claim that it heavily rolls off a 23Hz note, making it inaudible. You then report a conversation with AI staff, where they say things that are utterly impossible in electrical engineering terms, and yet you claim that I am being 'inappropriate and offensively discourteous' by noting their lack of expertise? Why will you not acknowledge the *only* two possibilities he 1) The preamp is seriously malfunctioning 2) No such difference exists in the physical world A simple measurement would show which is the case. I would recommend having it done in situ, rather than letting AI get their hands on it. BTW, I note that, in terms of 'offensive discourtesy', you accuse me of double standards, and of having refused to clarify my endorsement of a particular component. Yet, when I ask you for some evidence of what 'clarification' was requested, you are utterly silent. Double standards, indeed................... -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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Stewart Pinkerton wrote:
On 26 Oct 2004 00:01:07 GMT, Steven Sullivan wrote: Everest's 'Fundamentals of Acoustics' retains in its current (4th ) edition a figure from previous editions, (Fig 5-12 in the 4th) derived from a 1982 study by Fiedler of the dynamic range of live 'classical' concert music. This shows a maximum range of 118dB for close-mic'd percussive symphonic music, and 113 dB for typical symphonic music without an audience (micing conditions not stated, but presumably not close-mic'd). Everest describes the this as follows: "Fiedler's study has shown that a dynamic range of up to 118dB is necessary for subjectively noise-free reproduction of music. He considered the peak instantaneous sound level of various sources ... and the just-audible threshold for white noise added to the program source whent he listener is in the normal listening situation. He used musical perforamcnes of high peak levesl in ta quiet environment and a very simple recording setup. ...the signal to noise ration offered by a16-bit PCM system is shown to be inadequate for all but piano solo. Future developments will undoubtedly require greater dynamic range than that offered by 16-bit digita;l systems.' So, leaving aside the prevalence of 16-bit recording setups these days, has Everest misinterpreted Fiedler's data or is there another dimension to the story? (Fiedler LD . 1982. Dynamic range requirements for subjectively noise-free reproduction of music . J Aud Eng Soc, 30:, 7/8, 504-511.) Oh dear, not the Fiedler fiddle again! It's hard to know whether this was a deliberate distortion by Fiedler, not picked up by Everest, or simply an engineering figure that is being misinterpreted by the reader. Given the convenient claim that 16 bits are inadequate, I tend to suspect the former. However, the following are why this is not a realistic figure to use for determining real-word requirements: The part I quoted (minus the ghastly typos, which are all mine, and the elisions, which are where the Figure numbers were in the original ) was what Everest wrote. Not having seen the Fiedler paper, I don't know if Everest is paraphrasing what Fiedler wrote, or applying his own interpretation. But I did get the figure quite wrong. In glancing at it whilst typing, I mixed up DR and max SPL numbers. Here's what it actually shows: condition: base SPL/dynamic range/peak SPL piano solo 13dB/90dB/103dB typical classical symphony (tcs), w/audience: 13dB/100 dB/113dB tcs, w/o audience: 8dB/105dB/113dB tcs, close mic: 4dB/109dB/113dB percussive classical, close mic : 4dB/118dB/122dB 1) The 118dB figure refers to close miking. Note that in many orchestras, the poor players sitting in front of the brass section often use acoustic baffles to prevent hearing damage - and to allow them to hear their own instruments! This is definitely *not* a realistic figure to use, when it is not representative of what any audience member would hear, even from the very front stalls. Is it possible that a recording of the un-natural (and perhaps highly multi-miked) kind might be close-miked? 2) I believe you'll find that the 113dB figure also refers to close miking, as the difference quoted is simply that between heavily percussive and 'normal' symphonic events. I'm not aware of any figures taken from the usual 'simple miking' position about twelve feet above and behind the conductor, which exceed 110dB peak SPL for any orchestral piece, including Mahler and Wagner. As I note, the actual max DR in the figure for all situations other than close-miked percussive classical is 109dB. But peak SPL is 113db for those, and 122dB for the close-miked percussive classical. 3) Please note the base measure used for the above - the just-audible threshold of white noise in an otherwise quiet environment. This is 0dB SPL. IOW, what Fieldler is quoting is peak SPLs at one end of the range, and assuming a 'threshold of hearing' bottom limit. This is farcically unrealistic even for a studio recording, where the self-noise of the *microphones* will be above 20dB SPL, and the true wideband noisefloor of the venue will be not less than 30dB. Move to a real reverberant concert hall, where the music will always sound better than an artificially reverb'd studio recording, and the noise floor will jump to a typical 40dB. It appears from the figure that he only assumes 'threshold of hearing' as the bottem end of the dynamic range in the two close-miced cases , where he labels the bases 'hearing actuity, 4 dB eqv' The w/o audience case is labelled 'mic noise, 8 dB eqv" and the remaining , w/audience cases are labelled 'audience noise, 13dB eqv" -- figures which look to be drastically quieter than the noise floors you cite. So I remain puzzled that Everest, writing a 'Master Handbook of Acoustics', would cite this figure uncritically edition after edition. I will be happy to scan this figure in and post it somewhere, if anyone wants to see it. 3a) Note that when we're back in the real world, that artificial reverb which is *essential* to avoid a studio recording sounding horribly sterile, will in and of itself raise the noise floor by 4-8 dB. 4) Despite the desperate attempts by Fiedler to come up with some reason why we need hi-res replay formats (note that no one denies the usefulness of 24-bits for *recording*, to allow room for accidental mic overloads and EQ), there is no record of *any* real master tape of an acoustic musical event (i.e. no synthesisers) which exceeds 80-85dB dynamic range, and indeed most 'live' classical recordings have more like 60-70dB range. Why therefore does Fiedler claim that we *need* more than 93dB? More importantly, why is he using the utterly unrealistic 0dB SPL as his base reference? And I wonder, again, why Everest keeps quoting it? -- -S Your a boring little troll. How does it feel? Go blow your bad breath elsewhere. |
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Stewart Pinkerton wrote in message ...
On 26 Oct 2004 00:07:31 GMT, (Robert C. Lang) wrote: Chung wrote in message ... Robert C. Lang wrote: Chung wrote in message I attempted (during the course of this thread) tried to find some independent measurements done of the 3A. So far I have not been successful. Try something sophisticated - type 'Audible Illusions 3A' into Google. The first two hits should be the Stereophile review. This technical review shows a frequency response ruler-flat to 10Hz, the lower limit of their measurements. I was already familiar with the Stereophile measurements, besides you had already made reference to it in another post. I was looking for a measurement other than those from "Stereophile". Don't get me wrong, that is an excellent start, but I have always viewed Stereophile measurements as more "quasi-independent" than truly "independent" because the manufacturers, as a practice, provide "handpicked" units to the magazine for review. I was looking for a measurement done in the vein of those done by Consumer's Union (not by Consumers Union which would be highly unlikely). That is, I was looking for a review/measurements whereby the reviewer purchased (or borrowed if absolutely necessary) the unit from a dealer where it would be less likely to be a "ringer". Consumers Union does this for *very* good reason. They found evidence early on that when they got products directly from the manufacturer it was all to common that, if it was not an "over achiever", it was more likely to meet spec than the product the consumer could buy. But if this type of review is not available(I realize that it may not be) I was looking for any other measurement done by another reviewer. Have your "sophisticated" searches turned up measurements other than those done by "Stereophile"? Robert C. Lang |
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"Chung" wrote in message
... Robert C. Lang wrote: In addition, my opinion of roll off of bass below 30 hz in *my* system was backed with the unanimity of two engineers and Mr. Ferris at Audible Illusions. Did those people listen to the M3A in *your* system and agreed that the bass was indeed rolled off? Or did they simply agree with you without listening to it, but having made measurements on it? One factor that has not been noted yet is the Fletcher-Munson effect. If you take a look at the audibility curves for 20Hz you will notice that it takes 70db SPL to hear _anything_ at 20Hz, and that the 10 sone steps are only about 3db apart above that. What this means is that a small increase in bass output makes a large difference in sound level to the ear--and vice versa. A rolloff that would be minor at 1kHz might be the difference between sound and no sound at 23Hz. I took note that the new organ in Benaroya Hall here in Seattle uses 3 pipes tuned to 32'C and C#, and 2 up to E flat. Norm Strong |
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Stewart Pinkerton wrote in message ...
BTW, I note that, in terms of 'offensive discourtesy', you accuse me of double standards, and of having refused to clarify my endorsement of a particular component. Yet, when I ask you for some evidence of what 'clarification' was requested, you are utterly silent. Double standards, indeed................... Frankly, I did not pursue it because, while it helped support my point, it was not the point. It was no big deal that a response from you was not forthcoming. That's your choice; there was certainly no obligation for you to respond. I don't necessarily consider that to be discourteous, maybe mildly discourteous under some circumstances, but certainly not the offensively discourteous behavior that you have flaunted in this thread. Responses don't happen for a variety of reasons. You could have been busy addressing more important issues of everyday life, you could have simply overlooked my request, perhaps you submitted a post that simply didn't make it through (I periodically have had server issues that have caused lost posts that show up on some servers but not others or not at all) or you could not have had anything pertinent to say, in which case it would have been best to say nothing. My point was that you should not hold "opinions" or observations to the same standards of evidence as "claims", particularly since you don't adhere to those same rules yourself. And if you do make a request for "evidence" to support an "opinion" or observation and you don't get what you asked for, to go into a strident rant and become uncivil, as you well did, serves no useful purpose to the discussion. Besides, your response now would be 10 months late and of limited value to me. Further, I provided the date of the exchange, if you were interested it you would have looked it up yourself. But if you insist on providing clarification to my 10-month old request, please do so both based on your experience with the product at the time, as well as any current experience or knowledge you may have. The exchange went like this: I said: I'm attending CES specifically to narrow my choices for a universal player so I can listen to DVD-A as well as SACD and CD. You said: Pioneer DV-868 - accept no substitute! :-) I said: An enthusiastic endorsement, indeed……….. Though, the unit "looks" nicely crafted. But what is the basis of your endorsement above other universals in Pioneer's line or above other brand universals? Any hands on experience? Have you listened to it?" End of exchange. Note, I did not ask you whether or not you had "measured" the Pioneer or for any other empirical data or evidence, even though such may be your advocation, because, as stated it clearly was your "opinion" and nothing more or less. To request empirical data would have been, in my opinion, disingenuous. I would have been pleasantly surprised if you had gone that far. But any information that you provided to support your "opinion" would have been greatly appreciated at the time. Robert C. Lang |
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Uptown Audio wrote:
Well Dude, perhaps amplify prior to the input of an amplifier, ie preamplify? -Bill www.uptownaudio.com Roanoke VA (540) 343-1250 "Tat Chan" wrote in message ... Dude, what else is a pre-amp meant to do other than act as a source selector and volume control? As such, a pre-amp should be nothing more than a connection (maybe with some gain) to the power amp and as such have no distinct sound of its own. I did mention that "maybe with some gain" so that does include a normal pre-amp, but I should have clarified that I was refering to a "passive pre-amp". |
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Stewart Pinkerton wrote in message ...
On 26 Oct 2004 00:08:30 GMT, (Robert C. Lang) wrote: I want to make a brief amendment to my last reply to Bob Marcus. I said, in part, about the Audible Illusions 3A that: "It is still a superb line stage that I strongly recommend, if you don't have speakers that reach to the lower octave and/or you don't listen to organ music that may reach that low". My caveat should be deleted and rephrased to say that if an audiophile is so inclined he or she should audition the 3A in their system irrespective of how low their speakers go or what music they listen to, because their experiences, particularly in the lowest audible octave, could be different than mine. If the unit is not broken, they could not fail to be different, since this unit *measures* ruler-flat to less than 10Hz. And of course, there are other limitless possibilities that you have enounced, some of which: 1) That the unit was broken even though Audible Illusions said it was not. But given your declaration that key employees, including engineers, "sound like classic 'high-end' clowns", which if true, leaves open the distinct possibility that the unit was indeed broken but that Audible Illusions was too inept to figure it out. 2) That my observations of the unit's performance in my system was, as you declared, "Your imagination seems to be the most likely culprit", even though a)I could clearly *see* that lamps and other furnishings in my listen room did not vibrate as they typically do during said passage of the Poulenc Organ Concerto, b) I could not *feel* the usual flutter of the floor during the said passage, and c) I could not *hear* the *90* second *continuous* bass note as I have with other line stages, all this even with the volume turned higher than normal. And, of course, 3) That old standby, "something was *seriously* wrong with your system", as you spouted without giving even a smidgen of a clue as to what that might have been wrong. As I have said before, if you look at the Audible Illusions spec sheet and compare it with my personal experience, things don't add up. Heck, I realized that when I first made my Audio Review comments in February 2000, almost 5 years ago and when I explored possible explanations with Audible Illusions during that period. Remember I have known Audible Illusions for years (probably since the 80's before it gained a national audience) because it was one of the first high-end manufacturers to be locally based around here. We have had high praise for its products, but we also know that it has had a reputation, at times, for being somewhat uneven, with respect to its products. I believe even Stereophile made mention of that to some degree. Regardless, I was not going ignore my personal experience of the 3A in my system just because Stereophile had given it a glowing review on a single unit. This is why I, in part, reject your unrelenting reliance (you have held it up as being an unimpeachable reference several times) on a single measurement, done on a single hand picked unit, performed nearly 9 years ago by Stereophile. Scarcely scientific. Robert C. Lang |
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This all could be true, I don't know. This also dovetails, I believe,
to the questions that Mr. Chung asked yesterday. He asked: Did those people listen to the M3A in *your* system and agreed that the bass was indeed rolled off? Or did they simply agree with you without listening to it, but having made measurements on it? The answer to the first question is, of course, they agreed with my conclusion without having listened in my system, even though they had the opportunity to do so. To the second question I have no answer. It could be that they did measure, but I don't know what they found if they did. If I recall correctly, they told me that they "checked out" the unit and found it OK. Mr. Art Ferris of Audible Illusions then sent me the Email that included the explanation that we *all* have taken issue with. While I agreed with their conclusion that the unit rolled off in my system, I certainly did not buy their explanation that I found convoluted, as to why it rolled off in my system. To put this in to some (not complete) perspective it should be understood that this all took place almost 5 years ago (February 2000). (My comments about my experience to AudioReview.com were made on February 27, 2000). I initially chose the 3A as my first (and only) choice initially, because it was a local company, it appeared highly regarded and I was probably swayed (I don't remember) by the good review that it recieved in Stereophile. I'm not a bass or organ freak but I do love certain organ pieces and I *love* Poulenc's Organ Concerto and have heard it performed live on several occasions (I would not miss an opportunity) including two performances by Michael Murray who is the organist on my Telarc Performance. That 90-second continuously held 23hz note toward the end is simultaneously delicately ethereal, intensely powerful and undeniably unique. Since the Audible Illusions 3A was the only pre amp I was considering I did not expect, not even remotely, that it would not pass that note. After all my 11-year-old budget PS Audio at the time did it nicely. Of course, none of that proves anything and nor is it intended to. So, some ask why did I not take measurements of the 3A? Why did I believe Audible Illusions when they admitted that their product would not perform? Why did I not bother to conclusively prove them wrong or right? For what? While I had a strong preference for the 3A I certainly wasn't inextricably married to my initial decision. I had a preamp (PS Audio 4.5) with a noisy transformer and I wanted another preamp. Besides, the Audio Buyer's Guide (1999 edition) listed over 200 preamps on the market. Why fiddle around with Audible Illusions just to make a moot point? So I moved on. My guess, but I believe there are few among us who would have pushed the issue with Audible Illusions under those circumstances. That was one of the best audio decisions I have made. I listened to in my system 4 other line stages from BAT, Ayre, Placette Audio, and one other. I settled on the Placette Audio for a number of reasons including it being a passive line stage. I like the philosophy. And yes, it passes that 23hz note with gripping realism. Fast-forward 5 years to today. Yes, I probably would pursue the apparent Audible Illusions failure, if only for the, experience, curiosity and fun of it. But as you suggest Audible Illusions may not want to know the absolute truth. Robert C. Lang |
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#117
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Robert C. Lang wrote:
This all could be true, I don't know. This also dovetails, I believe, to the questions that Mr. Chung asked yesterday. He asked: Did those people listen to the M3A in *your* system and agreed that the bass was indeed rolled off? Or did they simply agree with you without listening to it, but having made measurements on it? The answer to the first question is, of course, they agreed with my conclusion without having listened in my system, even though they had the opportunity to do so. That is a sign of incompetence, or at least (and even worse IMO), a lack of the intellecutal curiosity that is so common among the better engineers. I certainly would not expect a reputable company to simply accept your conclusion that 23Hz response is way down from this preamp. To the second question I have no answer. It could be that they did measure, but I don't know what they found if they did. If I recall correctly, they told me that they "checked out" the unit and found it OK. Maybe they had a technician check it out on a 'scope with an input impedance of 10 Meg. In which case, a coupling cap with a much smaller value might still give the right response. Assuming that there is indeed something wrong with the unit, of course. Mr. Art Ferris of Audible Illusions then sent me the Email that included the explanation that we *all* have taken issue with. While I agreed with their conclusion that the unit rolled off in my system, I certainly did not buy their explanation that I found convoluted, as to why it rolled off in my system. That's funny the way you put it. You agreed with their conclusion, which was that they agreed with your conclusion?  In other words, you simplyagreed with your conclusion. To put this in to some (not complete) perspective it should be understood that this all took place almost 5 years ago (February 2000). (My comments about my experience to AudioReview.com were made on February 27, 2000). I initially chose the 3A as my first (and only) choice initially, because it was a local company, it appeared highly regarded and I was probably swayed (I don't remember) by the good review that it recieved in Stereophile. I'm not a bass or organ freak but I do love certain organ pieces and I *love* Poulenc's Organ Concerto and have heard it performed live on several occasions (I would not miss an opportunity) including two performances by Michael Murray who is the organist on my Telarc Performance. That 90-second continuously held 23hz note toward the end is simultaneously delicately ethereal, intensely powerful and undeniably unique. Since the Audible Illusions 3A was the only pre amp I was considering I did not expect, not even remotely, that it would not pass that note. After all my 11-year-old budget PS Audio at the time did it nicely. Of course, none of that proves anything and nor is it intended to. So, some ask why did I not take measurements of the 3A? Well, actually I said that you *could* have made measurements, not that you should. Why did I believe Audible Illusions when they admitted that their product would not perform? Why did I not bother to conclusively prove them wrong or right? For what? Curiosity? Because what they said was plainly ridiculous? |
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B&D wrote:
On 10/30/04 1:05 PM, in article , "Chung" wrote: The answer to the first question is, of course, they agreed with my conclusion without having listened in my system, even though they had the opportunity to do so. That is a sign of incompetence, or at least (and even worse IMO), a lack of the intellecutal curiosity that is so common among the better engineers. You cannot draw any conclusions about AI's engineers with all this third hand information. Wait a minute. The conclusions drawn are based on the third hand info. If such info is wrong, then of course the conclusion is wrong. In other words, given what Mr. Robert Lang wrote, the conclusions are valid. They may not have had the budget or time to dig into anything - and assuming they are testing their gear before publishing specs, probably thought it was easier to pass up the sale than go any further. In that case, they should just say they did not have time to dig into anything. They said, however, that the product checked out OK. Given that engineering time in the SF Bay area is, with overhead about $150-250/hr -- and the Gross Margin on a preamp is likely to be around $800 - 1000 - it would only take a few hours before they would be losing money on one sale of one preamp. Is that how you work? If there is a potential problem in your design, you shrug it off because your time is too valuable? Intellectual curiosity may be alive and well - but the accountant and business reality may be shutting it down. If that's the case, then the engineer should not have been involved in the first place. But they were involved. They will probably track the complaint - and if it hits a certain level it will probably unleash the engineers. A small boutique manufacturer should be even more interested in protecting their reputation and providing superior custom service. What you said perhaps may describe some huge conglomerates. It is unrealistic to expect the full force of a company to be used to address a single customer problem if it looks like it could be anywhere near time consuming. No one is expecting that. The customer simply wants to know if there is anything wrong with the unit, and it's a 5-minute test. |
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On 30 Oct 2004 19:53:09 GMT, B&D wrote:
On 10/30/04 1:05 PM, in article , "Chung" wrote: The answer to the first question is, of course, they agreed with my conclusion without having listened in my system, even though they had the opportunity to do so. That is a sign of incompetence, or at least (and even worse IMO), a lack of the intellecutal curiosity that is so common among the better engineers. You cannot draw any conclusions about AI's engineers with all this third hand information. They may not have had the budget or time to dig into anything - and assuming they are testing their gear before publishing specs, probably thought it was easier to pass up the sale than go any further. It would take about ten minutes with a signal generator and voltmeter to check this gross error. So much for engineering integrity, customer care and quality control....... Given that engineering time in the SF Bay area is, with overhead about $150-250/hr -- and the Gross Margin on a preamp is likely to be around $800 - 1000 - it would only take a few hours before they would be losing money on one sale of one preamp. Intellectual curiosity may be alive and well - but the accountant and business reality may be shutting it down. They will probably track the complaint - and if it hits a certain level it will probably unleash the engineers. It is unrealistic to expect the full force of a company to be used to address a single customer problem if it looks like it could be anywhere near time consuming. See above. If I were running such a company, a loud alarm bell would ring if a customer reported audible loss of bass on one of my units which was specified flat to 2 Hz.................... -- Stewart Pinkerton | Music is Art - Audio is Engineering |
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