Is there a real benefit to preamps or two channel amps in HT?

[Wayne A. Pflughaupt]

dtb300’s has been terminated for his rude and confrontational tone, and for not editing his posts when requested. I commend the rest of you guys for keeping it civil and not getting sucked in.

Regards,
Wayne

[macrae11]

DS-21 wrote:

I think that's as good a summation of the current state of audio electronics as any, so long as certain assumptions aren't broken. For amps, that they can safely drive the load one's speakers present and have sufficient power to reach the desired listening room SPL, for instance.

Obviously, those statements do not apply to speakers, turntable cartridges, etc. In those fields, it does take a considerable sum of money to get really great sound.

Well I'm not sure where to start with this. I guess I'll start with my experience first.

I'm an audio engineer by trade. Audio engineer's come a little from the other side of the fence of most home theatre buffs. Our gear buying isn't a hobby, it's a business. We can't buy a piece of gear just because it matches our decor, or because the company has a good service reputation. The only reason we buy gear is to make money from it. If buying a new piece of gear won't make us money, generally we don't buy it.(Although we can still be subject to the ubiquitous GAS, or Gear Acquisition Syndrome.) As such we won't buy a piece of gear that is more expensive than another piece of gear, unless it is going to make us comparably more money to justify the price difference. Now sometimes there is the bling factor, where buying a certain brand, or a nice looking piece of kit will attract more customers, but most of the time that's not an issue.

Specifically looking at two pieces of gear, pre-amps and power amps, the only real buying influence is performance. Not colour, or aesthetics, or even usually features, as features on these units are typically all the same: they make signal louder. So why do we spend x thousands of dollars more for primo equipment, when we could spend a few cents on the dollar and get the behringer, or realistic, or X budget brand unit? Because it sounds better. Even with the same amp types, power ratings etc. If you could get accurate specs out of the budget piece, you can see it on paper, but you don't even have to, it's easy to hear. Now I'm not saying it's the type of difference like going from iPod earbuds to Grado headphones, but it's not some little unquantifiable audiophile difference like "danceable" cables. In other words my wife can hear it.(just for clarity, she is almost tone deaf and doesn't care at all about audio)

These difference have been proven time and again by well calibrated double blind ABX tests, where the better quality gear stands head and shoulders above lesser quality gear. Notice I didn't say the more expensive gear, because it's certainly not always about price, it's about quality. And always, even if there's not a clear "better and worse" there is almost always a difference. Two pieces of gear doing the same job, in the same class with the same power, almost never sound the same, to the discerning ear.

So that is my definitive experience. Different pieces of gear, of similar build parts, power, capabilities, and function sound radically different. Whether it is better or worse is based on your own personal aesthetic. Now some might argue, that this is in a recording studio, it doesn't affect home theatre. But these are the same pieces of gear, doing the same jobs, just at the other end of the signal chain.

[Blaser]

I have seen posts about sound quality discussion that caught my attention. SQ is not about listening tests or better DAC or whatever. SQ refers to fidelity with regards the input signal. An amp that distorts the output the least will be provide the best SQ. This cannot be determined by listening tests or mood (what sounds good to your ears today might be unappreciated tomorrow), but measurements.

[macrae11]

DS-21 wrote:

Intuitively, to me that would lead to the conclusion that durability and the maker/marketer's service reputation are crucially important. Perhaps as much so as sonics. But it's not my industry.

Sound quality is paramount above all else. Service after the sale, is certainly important, and takes consideration, but really only after the sonics are more or less equal. This is why people still use pieces of equipment that are 50 years old, have no suitable replacement parts, and are in constant need of upkeep. Just to get that sound. Now after the repairs and downtime become more costly, than the benefit of having that sound, then service issues become much more important. Just trying to make a living you know. Gets harder every year in this business too.

Alternately, because it is better designed for the duty cycles required in your line of work. Some of the Behringer stuff may well not be suited for high-duty commercial audio use. However, the fact that it isn't - or priced like gear that is - does not preclude its use in top-flight home stereos. (I don't own any Behringer gear right now, because I find it ugly and have equal or better functionality from other stuff that better fits my aesthetic preferences.)

Certainly Behringer doesn't suit my aesthetics either, for a variety of reasons. Behringer has made a few decent products that I've used, but in general, amongst the products that I've used, their noise floor is higher than competing products, they're are not laid out as well, they use shoddier components, and they are far more prone to failure. These things I would think affect the home theatre enthusiast as much as the professional user. Of course this also doesn't say anything about their corporate ethics issues for which they are almost as infamous as their product line.

DS-21 wrote:

Ugh, I think I'd rather listen to awful iPod earbuds than Grados, because at least the iPod buds were free. I'm not into paying to torture my ears. (I'm a Sennheiser '580/600/650 + Ety guy.)

Again just a preference thing. I'm a big fan of the 650's although right now I'm mostly using a pair of Beyerdynamics.

DS-21 wrote:

That's the kind of statement that requires a cite, given the overwhelming weight of evidence (starting at the very latest with Clark's 1983 JAES paper) to the contrary. Assuming, of course, that factors known to be audible (FR, certain orders and levels of distortion, noise, etc.) were not measurably different between the two. I think such a finding would be at the very least highly publishable and of enormous marketing value to the firms whose gear prevailed in such a session.

emphasis added.

Ok I guess this is where the rubber meets the road, and where I think our two arguments meet. All the double blind ABX tests that I was referring to, were ones that I either designed myself or was present at. Thus there was no official publication of our findings. Here's the key: Of course if there is a sonic difference there will also be a corresponding measurable difference. I never claimed that there wouldn't be a measurable difference, however often these differences will not show up on a standard spec sheet, which is often what people are using to judge which product to buy. For example on a spec sheet from a Behringer preamp(which I used to own by the way) the THD is measured at .001%. On a Millenia preamp, which is one of the more revered transparent preamps, the THD is also measured at .001%. So if we are to simplify the comparison down to this spec, by your logic the two pieces will sound identical. This however is not the case. When we dig a little deeper, the behringer offers no other information. However the Millenia product states that the THD .001% from 10Hz-20kHz at +27dBu output. Quite a different story is told.

I never would have bothered to argue your point if you had said that two pieces of gear that have identically measurements will sound the same, but that wasn't your initial statement.

DS-21 wrote:

But outside of improvements in signal processing, anyone making a statement about personal preferences regarding sound quality in the commodity parts that are modern audio electronics is simply deluding her/him-self and possibly wasting money. It doesn't sound better, unless one of the two pieces of gear are broken.

This is your initial statement which I take opposition to. You weren't claiming that different pieces of equipment with the same specs sound the same, you were saying that all equipment sounds the same. I would also say even if the specs are the "same" two pieces will still sound different as specs never tell the whole story.

The other thing when using measurements only as a gauge of sound quality, you need to measure every possible component in every possible quantifiable way. Not easy to do, and never done on a spec sheet. With a proper level matched ABX test I can very quickly discern if there is a difference in sound quality. I may not be able to tell you what the exact difference is, or even which one you'll prefer, but I will be able to tell you if there is a difference or not. You can easily verify this with a null test.

Also we haven't talked about different types of components. IC's don't sound the same as transisters which don't sound the same as tubes. You stating that all modern audio components sound the same, ignores all of these variables. So a seperate transistor preamp and tube power amp are going to sound different than an IC AVR. Better or worse is not for me to say.(although you could probably guess my opinion.)

DS-21 wrote:

No argument here. At all. The idea that DSP will correct for severe flaws in system design such as haphazard speaker placement, non-constant directivity in the midband, use of a toppled-MTM center channel, or inadequate radiating area for low-distortion, low-compression lower midrange reproduction is off-base. However, I do not believe anyone here holds that position. I think the prevailing view (or at least my view, which if it isn't the prevailing view should be it) is that room correction is like the cream you put in after you've brewed a great cup of coffee in a French press. Start with bad coffee, and you'll never get there. Start with some coarsely ground Julius Meinl Jubilaeum blend, and you'll get a perfect Viennese melange.

Just a different methodology then. You're choosing to add your own flavour after the fact rather than listen to the ideal of what the artist wished to create. This is not a bad thing, just maybe not the way of the purist, who would drink their coffee black

[macrae11]

tonyvdb wrote:

You make some good points in your above post my only comment is on this section. You have to remember that an EQ or the so called room correction system is to get the sound coming out of the speakers in a room to sound like the original recording as close as possible. The problem is that room acoustics severally effects the sound, a "perfect room" should need little correction of the sound and a flat response is what you would get "if" the speakers are designed properly without any color. The issue is this is rarely the case. The other problem is that some recording studio's dont follow the rules and tweak there system so it is not flat to begin with and adds color to the sound even before it is mastered.

Yes unfortunately as was in the article I posted, EQ can never fix room deficiencies. A "perfect room" should need no correction, regardless of the speakers used. However there are precious few of these rooms in the entire world. I can only think of one of the top of my head which might even be considered.

As far as the recording studios, changing the response of their monitoring systems, this is generally frowned upon, and rarely happens. More often is the case that perhaps the studio can't afford proper monitoring or room treatment. Either way it is rather irrelevant as this is the point of creation. If the artist got things how he wanted to sound in that room and it translates well to other systems than the project, and the room that it was created in was a success. Proving again, that in the creation of art, there are no rules.

[macrae11]

Wayne A. Pflughaupt wrote:

Assuming Rod Elliot was referring to equalization, we get a contrasting (conflicting?) view from Rane’s Exposing Equalizer Mythology by Dennis Bohn (bold emphasis added):

“Phase shift is not a bad word. It is the glue at the heart of what we do, holding everything together. That it has become a maligned term is most unfortunate. This belief stands in the way of people really understanding the requirements for room equalization.

Associated with each change in amplitude is a corresponding change in phase response. Describing them as unbelievably jagged is being conservative. Every time the amplitude changes so does the phase shift. In fact, it can be argued that phase shift is the stuff that causes amplitude changes. Amplitude, phase and time are all inextricably mixed by the physics of sound. One does not exist without the others.”

I think what Mr. Elliot failed to consider is that equalizers also introduce phase changes, which probably accounts for how it’s usually possible to EQ phase-related response problems around a sub’s crossover region.

Overall though, that was a very good article. Thanks for linking it. I especially liked the part about mics not "hearing" the way our ears do. That's probably why you don't get much of an audible improvement equalizing subs beyond smoothing out the worst problems. I.e., piling on lots of "minutiae" filters smoothing out every little ripple in response you probably won't be able to hear the difference with them in or out. I sure can't.

Regards,
Wayne

You are correct, but I belive Mr. Elliot was thinking on a slightly different line. Of course when dealing with EQ's amplitude and phase are related(with the exception of a linear phase EQ). In the real world(no EQ) they are not so incontrovertably linked. You can have the identical phase of two signals with two completely, even opposite amplitudes. Also the time which Mr. Elliot and yourself are referring to are on different scales. a 10 degree phase shift at 80 Hz (wavelenghth of 4.2m) takes a little over a 1000th of a second. Room nodes can cause differences in time of an 80Hz note of a second or more. So an EQ(even a very poor "phasey" EQ) can come nowhere close to adjusting that kind of time.

PS. Someone please correct me if my math is wrong, it's been quite some time since I've had to work out any formulas.

[macrae11]

DS-21 wrote:

I don't doubt any of that. However, "that sound" as you put it is by definition a coloration, a deviation from sonic accuracy. I'm proceeding from the assumption of someone interested in recapturing what someone like you originally put on the disk/file, which is that the sound one wants from one's electronics is no sound at all. Such sonic transparency is by and large attainable today for very, very little capital outlay in electronics, because most gear from the middle-low-end to the middle-high-end is designed for that end. At the blue light special end, one's more likely to see nonflat FR, e.g. the Sonic Impact T-amp, which sounds so much like a SET because it has no power and significant rolloffs at the frequency extremes. Likewise, much of the stuff at the tippy-top of the "high end" is not so much "designed" as "haphazardly thrown together on a kitchen table," though there are certainly exceptions in the bleeding price sphere (Meridian, Lexicon, TacT, etc.).

Colouration is not always the goal. Often pure transparency is required in a piece of gear. Particularly amplifiers. True transparency can be just as expensive as boutique "flavoured" gear. Now it's possible that manufacturers can use cheap IC components to create pure sonic transparency for just a few dollars, but if they can, there must be a huge conspiracy amongst all the manufacturers to gouge us end users, by not releasing these cheap transparent pieces of equipment. Ockham's Razor would disagree, but this certainly doesn't mean that it's impossible.

DS-21 wrote:

With that caveat in place, I agree that we're more-or-less in agreement.

The only difference then, perhaps, is whether a corresponding measurable difference falls within the range of audibility. I don't think that just because there's a measurable difference there will be an audible difference. Take THD, which is by-and-large a meaningless number anyway. A difference between 0.0001% and 1% THD may not be at all audible, depending on where it falls. If it's 2nd order distortion, then it probably won't be. If the distortion spectrum is a high odd order, then it is far more likely to be audibly different. That's not to say that higher measured accuracy isn't ipso facto "better," but only that when one thinks of an audio system in its totality for someone with limited resources, the wise and rational course is to spend as little on things of no to debatably marginal audible difference, and transfer the money that would otherwise be squandered on commodity boxes into superior speakers and

Absolutely, not all measurement differences are audible. Also all audible differences are somehow measurable. However what is audible to some might not be audible to others. I'm not talking about these "golden ears" who supposedly have hearing like dogs. It has more to do with training. For example, my hearing is very good(tested annually by an audiologist), however I am still learning to hear things that I have never heard before. Depth for example can be something difficult to quantify. Particularly with a mono source. However a much more experienced engineer and I did an ABX shootout with some microphones, and he showed me how with certain mics depth can be achieved with a mono source. I couldn't hear what he was talking about at first, until he started to describe it to me, and then bam! I could hear what he was talking about. After that, I could hear this every time, and even compare this new variable between other mics. This is not a function of the human ear but of the brain. I became aware of what my ear was hearing all along, making it a reality for me. My hearing will continue to deteriorate as I grow older, and will never be as good as it is today.(without vast increases in medical science) However my listening improves every day.

DS-21 wrote:

I use the shorthand "broken" to cover "components with audible differences due to measured failings in one or more areas that cross established thresholds of audibility." Why? Because it's either broken in that something's physically working wrong, or "broken" in that the design process intentionally led to something deviating from sonic transparency.

With this in mind I consider from the point of sonic transparency that there are a great deal of "broken" audio equipment out there. I would even say the majority.

DS-21 wrote:

Here we disagree. I've done DBT's (can't call them full ABX because switching was manual rather than the superior method with a comparator box) that found tube amps (Sonic Frontiers) to sound the same as transistor amps (Classe, so by extension Adcom given that the Classe and Adcom amps sounded the same), and DBT's that showed rather unique chip amps (the TI PurePath DAC+amp stage in the Panasonic XR55 receiver) to sound the same as traditional bipolar chip amps. So I think that all of the currently available technologies can lead to sonic transparency if that was the design goal to begin with. Admittedly, for some of the stuff (mostly at the very high end) that is not necessarily the goal.

Now, I agree that badly designed tube gear is going to sound different. Not to say that someone may well prefer the colored sound. But sometimes it's just plain badly design, such as a conrad johnson preamp I once auditioned that had a massive channel imbalance. And no balance control, of course.

It is very difficult to do DB ABX tests with amplifiers. It requires a very complex testing system. One thing to consider. Even the absolute best tube designs are not completely linear, depending on signal level. So if you ran a hotter or quieter signal your findings could have been different. Also I would be shocked to find a tube amp and an IC amp that measure identically. Those measurement differences are there to be sure. So I guess what we're arguing is whether these differences are audible or not. Something one can really only decide for oneself.

DS-21 wrote:

Quite the contrary. A sonically transparent piece of gear will faithfully transmit all of the colorations that the recording artist intended to be in there. It won't add more.

True. I am just hypothesizing that your DSP adding EQ to final signal is colouring the original signal, despite what the gear might be reproducing.

DS-21 wrote:

Depends on the kind of purist. If one's trying to reproduce the perfect cup of coffee (for me, a melange from Cafe Havelka on Dorotheregasse in Vienna, which is what Gustav Mahler drank, kaffeekultur being of course an Austrian innovation that the Italians were more adept at marketing to the world), then one will of course add milk.

I was just trying to use he analogy to make a point. Not enough up on coffee history to keep up with you. I'm perfectly happy with Haitian Blue, 1 cream 1 sugar.

[Wayne A. Pflughaupt]

Guys,

Since the discussion was getting seriously sidetracked with the DSP / time domain EQ issue, we’ve moved that part of the discussion over to the Waterfalls thread on the REW Forum. That required editing some of your posts to keep both discussions intact, so hopefully I have accomplished that without mangling your posts too bad. Anyone still interested in commenting on the DSP / EQ thing, please post on the other thread.

Regards,
Wayne