Alex,
Don't lose heart on this. It's a discussion and whether everyone agrees or not with a particular viewpoint I think we might be making some progress on what is a tough and often debated subject. I'm not even sure I can fully state what the debate is about but somewhere near the center of the debate is a question regarding hifi equipment that deals with what can be heard and what can be measured.
Unfortunately, the issue sometimes turns a little contentious as some people dig in and then once they are certain of their position rather than playing nicely some folks resort to personal attacks. It's a fine line from a bit of humor to making someone feel bad. In my opinion the term "audiofool" (or however it's spelled officially) is kind of derogatory, but since I'm probably in that camp to some extent I'll suck it up and deal with it without getting too concerned by it.
I think like you / as you have expressed - that people can get to a point in a discussion where logic strongly defends a position but if the logic is based on faulty input, or incomplete input, the output can be faulty. I tried to make a case that said 500 years ago many people were very sure that the Earth was the center of the Universe, in part because we didn't have the knowledge and science to mathematically prove otherwise with a sufficiently demonstrable line of reasoning. For sure, when it comes to witch hunts we can burn witches at the stake over and over thereby proving that witches burn.
Lightening up the subject a bit, here is where I think we (some of us) left off. It is from retrolefty's summary:
Electro-mechanical devices (mics, speakers, turntable cartridges) may indeed be discernible depending on the specific devices being compared. If so it can also be measured, and if not, can be proven so via well designed double blind testing. Anything else is just human faith based imagination.While I believe, like you (I think), that this forum has a near religion-like belief in the infallibility of DBTs I think it was refreshing (to at least a degree) that we got to retrolefty's summary (which I think is a fine summary) because it at least leaves open the idea that different transducer designs (speakers, mics, cartridges, etc.) with mechanical components in audio systems can provide discernible audible differences. Up to that point I was starting to think that the prevailing thought here is that little or nothing of value is discernible by human hearing. I was starting to think that the alternative to an audiofool was an engineer who sat in his hifi room but who never actually listened to his hifi; rather his use of the hifi was strictly as a DUT that provided a reason to measure things. In this stereo-(pun intended)-typical view, the anti-audiofool derives 100% of his enjoyment from watching numerical, graphical, and other readouts of measurements and 0% of his enjoyment is derived from actually listening to music. Or if the anti-audiofool is not fully science oriented in their hifi endeavors they might occasionally listen to their hifi but have no sense what sounded "good" because there would be no reason to listen critically as long as the spec sheets and measurements show good numbers. All of this is of course a bit sarcastic but hopefully not too derogatory coming back the other direction.
My more sincere view is that the science oriented audio enthusiast relies extensively if not exclusively on specifications and measurements to help select, build, and install good sounding equipment at reasonable prices so as to in turn be able to enjoy listening to music.
Where we are in this thread is that we seem to have reached a consensus (but probably not unanimity) that people can hear the differences in transducers and that those differences have measurable explanations. We even went a step further (at least in retrolefty's summary) and said that if the differences couldn't be measured but they could be shown to exist with DBTs then perhaps some differences could be accepted as humanly discernible even if we have not yet come up with a way to explain the differences with test equipment of some sort. To me, this is progress.
Next we get to your subject: the amplifier. Fwiw, I'm with you. I think the current consensus in this forum is a bit dogmatic when we say that everything that needs to be solved with amplifiers has been solved. I'm not saying some amplifiers haven't reached a tremendous state of performance (ie, to a very high degree they amplify the signal faithfully without adding or subtracting anything) but I don't believe this is as widely true of amplifiers as some folks might think or want to believe. Having said that, I do think that making an amplifier go reasonably flat (say +/-0.25dB) from 1Hz to 100kHz is probably "easier" than making speakers that go from say 20Hz to 20kHz +/-3dB. And I think it is the relatively simple frequency response measurement (combined with perhaps a few other relatively simple measurements) that cause most people to hold firmly to the notion that speakers (and perhaps other transducers) are relatively "hard" to design and build, and amplifiers are relatively "easy" to design and build.
Before we go further on the seemingly contentious subject of amplifiers, I think it might be good to look at the “half-full” side of the discussion, ie the notion that at least some hifi performance can be determined by human hearing. Again, I am heartened by retrolefty’s summary as it acknowledges more belief in human hearing than I thought might prevail around here.
One of the biggest breakthroughs in this thread (for me) was the seeming acknowledgement that “imaging” is a real concept. Even our forum buddy Fungus seems not only ready to get behind the concept of imaging but he seemed to put it forward as one of the key determinants of an “ideal” system (along with bass response). Prior to this thread I would have bet that the scientifically correct hifi enthusiasts here would have dismissed imaging as an audiofool’s errand. So I was delighted to see that imaging is an accepted attribute.
What is imaging? Well, I couldn’t get Fungus to define it but here’s my attempt at describing it with an example. I think imaging is the notion that when you go to see (and hopefully listen to and not just measure) a jazz band in a night club you might have the piano in one place on the stage, the bass in another location, and the drums in yet another location (since they can’t all occupy the exact same physical location). Back in the early 1960s these types of bands were popular and they sometimes played in night clubs. In the night clubs people in the audience sat at tables having drinks as they listened (but probably didn’t measure). During these times a really good band with a record deal might have recorded some of their performances “live”. In the process a sound technician might have deployed two microphones (one relatively left and one relatively right) which enabled making a two track (stereo) tape recording and ultimately a LP stereo record. The microphones would have picked up the sounds of all the instruments and also other sounds – such as the people in the audience speaking, clapping, or maybe occasionally clinking their drinking glasses.
After the performance the recording would have been “mixed” by someone in a studio (perhaps in a team effort by sound technicians and maybe/probably with input from the band members). Here the band team would be relying on memories, impressions, preferences, and other subjective human input to determine how much of what was actually recorded on the tape during the live performance should be retained exactly as it was captured on the tape, and how much might be subject to editing. Perhaps the bass player wanted to hear more of the bass on the final version of the upcoming record, or perhaps maybe the band wanted to turn up the clink of a glass to help listeners get the sense of being in a night club.
The point is that with just two tracks (stereo) lots of sounds from various directions – not only left and right but also front and back were captured and transferred from the microphones to the tape to the record. All of this results in the capture of sonic location “imaging” information – right to left and front to back. When you listen to a good pressing of a Bill Evans record listen for the sonic image, ie the relative locations of the instruments and other sounds. Depending on your hifi setup you might be pleasantly surprised at what you hear. If you are really into it, try moving your speakers a few feet or inches to see if the location of any of the sounds move as a result. (In general, but not always, try making the distance between your speakers roughly the same as the distance from the plane of the speakers to your listening position.)
Now, how does the information on the record get played back by speakers in a room? Setting aside the “easy” amplifier, the speakers have to somehow convert electrical signals to mechanical motions and create acoustic energy that somehow conveys the “image”. In order for this to happen with “fidelity” (faithfulness to the original – as it was captured live and then mixed with “artistic” as well as engineering input), the speakers must be able to move air in a way that creates not only the frequencies (lows, mids, highs) but also the spatial imaging (left, right, front, and back) of the individual sounds, all while retaining the subtle details of the “original” sound which means that not only do the frequencies need to sound like they did, and in their respective locations, but with the same relative strengths (amplitudes) so that some sounds aren’t emphasized more than what was originally intended and so that some sounds some aren’t deemphasized more than intended. Why would some sound be emphasized or deemphasized? Well, consider our speakers working hard to be “flat”. If the speakers, for example, produce a 3dB hump at 100Hz, the sounds at 100Hz will come across significantly louder than intended by the original. Now do the speakers do all this by themselves? No, they do this depending on their own performance plus how they couple to acoustics of the room. Depending on the size, shape, and surface treatments of the room, the room is very likely to either emphasize (reflect) or deemphasize (absorb) some frequencies at the expense of others. So unless the room is designed (probably with lots of calculations when it was constructed) and then measured and treated (after it was constructed) with a knowledge of what speakers would be placed where in the room (and where relative to the listener), all of these acoustic variables could result in almost any sonic end result. This is why sometimes speakers (and overall systems) sound one way in a showroom and then sound noticeably different when installed at home in a different room.
So, back to Fungus’ post about bass response, one of the things we find is that given the wavelength of a low note, some bass notes might be longer than the length of a person’s home listening room. (A low note in “natural” music, for example, might be created by a 32Hz organ pedal). If the speaker is even able to go down to 32Hz on it’s own (sans room) at 0db (ie, “flat) – and most speakers can’t – then when we put that speaker in a room that is say only 18 feet long (ie, deep front to back) the 32Hz bass note is going to hit the back wall before fully completing a wavelength and then reflect back toward the front wall (never mind anything it hits in between), and so on and so forth. (I think a 32Hz audio signal has a full wavelength of approximately 35 feet). Meanwhile all the other frequencies are also going to be reflected or absorbed based on the size, shape, and treatments of the room surfaces. (These timing differences can be further exacerbated by any delay in speaker crossovers and/or the placement of individual drivers relative to the plane of the speaker.) These interactions are going to have a significant effect on the overall sound.
Now, back to imaging. Imaging is the is concept that if things were well recorded in the first place – with attention given to details – and if the details could be accurately retrieved from the recording (we have only touched upon the role of a stylus, cartridge, tone arm, and turntable) and if those details were transduced from the mechanical realm of the record to the magnetic and electrical realms of the cartridge while being mechanically supported properly by the tonearm and turntable and if the phono section of the preamplifier and the rest of the preamplifier faithfully amplified the phono signal before passing it to the power amplifier, which in turn faithfully amplified the signal into the speakers (we haven’t really gone very deep into speaker loads), and if the speakers were designed and built properly, and if the speakers were installed in the right locations in a properly designed room – well then, we might just have faithfully reproduced the spatial image as it was intended.
When we say we passed the signal from here (say the preamp) to there (say the power amp), we are just using brevity. In reality, the “signal” is a composition of all the many signals (as represented by the frequencies, amplitudes, and phases) that were captured way back at the night club.
So, what should we know about imaging? It’s a real thing and it’s filled with subtleties that once you experience it and know what you are listening for, it can make a big impact on your ears and your mind. Most of us know imaging left to right (as a stereo image) and many of us know imaging front to back, although I think most people think of imaging in a fairly gross (large) manner – perhaps as we know it from the THX signature sound as it blares and rumbles through a commercial or home theater. While the sound of a jet plane or a train can be very exhilarating, the same concepts of left to right and front to back can also be exciting in a more delicate and subtle way with the clink of a glass on a Bill Evans live night club recording.
So, what does this have to do with say an “easy” amplifier? (Btw, this is where I get called out as an audiofool.) I would like to know which measurement on an amplifier spec sheet is the measurement that tells just how accurately the “easy” amplifier reproduces the sonic image. I have yet to see this spec on any spec sheet. Now before someone jumps in and says “well, but if we measured frequency response, and if we did this phase test, and we applied these rigorous test procedures, etc, etc, etc. we could show just how well an amplifier handles imaging”. To which I would say, maybe so, but a) I don’t see such tests being done and reported, and b) I bet things like the transformer(s), capacitors, and a variety of other components and circuits will have an impact on just how well aligned the amplifier output - with all the micro signals that make the composite signal input - retains the fidelity of all those details. Further, while imaging is an attribute that took several paragraphs to describe, I’m betting there other some other sonic “attributes” that could, with further description and discussion, also be surfaced as potentially present and discernible, albeit subtle - and that often go unmeasured.
Next, we get to: what can people hear? My guess is that people as a species have similar hearing capabilities but within the species we as individuals have a fairly wide distribution of hearing capabilities. What we can hear is of course in many respects measurable (frequency response, etc.). But what we can perceive and recognize is perhaps a function of our learned experiences. Some people can listen to music and say “that was a C note” while others have no clue, or at least they have no way to accurately express what they heard. The point here is that just because some people can discern this, that, or the next thing doesn’t mean another person has the same capabilities. Hearing is a function of anatomy, but also training/learning. Likewise, the ability to express what is heard is also a skill.
In summary, I’m happy to “hear” (pun intended) that we could at least get to a consensus on retrolefty’s axiom. While it might leave some folks thinking that the axiom should have been extended to strictly electrical components such as amplifiers, at least it seems to have opened our thinking about what causes what and how the causes and effects might be expressed in both what we can measure and what we can hear (and in turn, attempt to describe).
PS, I’m really not trying to create a battle here – just trying to express some thoughts that lead to constructive discussion and possibly some learning for everyone, me included.
Peace. EF
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