Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

Fuses

Here’s a subject that simply drives some people nuts. Fuses.
Change the power fuse in a DAC or preamp and the sound changes, depending on the type of fuse you change to.

I first became aware of fuses and their sonic differences in the 1980s. We were working on releasing the 200C power amplifier, designed by Bob Odell. This 200 watt per channel amplifier was the best sounding power amplifier we had ever produced and we labored long and hard polishing every part and decision to perfection. In those days we relied upon an output fuse to protect the loudspeaker and the amp from each other. Too much current passes through the amp and the fuse blows, disconnecting the power amp’s output.

The prototype amplifiers didn’t have output fuses. It wasn’t until we got to the production versions that we added them, and that’s where the trouble started. The production amplifier didn’t sound as good as the prototype. Thinner, weaker, with less bloom and midbass strength characterized the sound of the production version, relative to the prototype. Why the two sounded so different was a real head scratcher. When faced with such differences, you start removing any differences between the two until they sound the same. It didn’t take long before we discovered the biggest difference was the damn output fuse. Short the output fuse with a clip lead and the fullness of the music returned.

This vexed us greatly because we wanted the sound of no fuse while enjoying the benefits of its protection. Different types of fuses sounded differently too. We gold plated the fuse and its holder to see if that would help. It did. But not a lot. We even tried bypassing it with a small capacitor. That helped to, but wasn’t a good idea. And neither solved the problem.

In the end we came up with a clever scheme. We took the feedback for the amplifier not from the amplifier’s output, but from the output of the fuse. Thus, the fuse was included in the amplifier’s corrective feedback loop, and the fullness returned to the music. (For those of you giving this some thought, we also added a 100Ω resistor in parallel with the fuse so if the fuse blew the amp would remain stable).

With the clarity of hindsight there are many explanations of why this mattered, damping factor changes not the least of them.
The point of the story is simple. Fuses matter. But why should they matter in the AC circuit? I don’t have a great answer handy. But we’ll look some more tomorrow.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

Measuring the wrong thing

There’s nothing wrong with using measurements to prove something – as long as you’re measuring the right thing – which is where the subjectivists and the measurementists often get off on the wrong foot.

Take for example, heart attacks. If you suffer cardiac arrest, you’re dead within moments. Right? Stopped heart = stopped life. Turns out that’s not actually true. Scandinavian scientists have discovered packing a person’s head in ice after cardiac arrest buys them time, and lots of it. In fact, they may not even perform CPR on them. We die not directly from the stopped heart, but from brain failure. In other words, when the heart stops the brain fails: one is the cause, the other the result.

When your heart stops pumping, blood to the brain stops flowing, calcium floods in, and your brain cells die. Pack it in ice, calcium does not flow, and you can survive without a heartbeat for quite a long time without damage. It’s why people falling into frozen lakes can sometimes be revived after even a few days. We don’t die from cardiac arrest, we die from the brain not getting blood (because of the heart failure). So measuring a person’s pulse tells us not the whole story, but a clue as to the outcome -which can be changed.

The point of all this is not to carry a bucket of ice if you’re prone to heart attacks. But rather to point out the fallacy of believing a limited set of measurements. Before our recent understanding of brain cell death, we could say with certainty that heart failure = death. Today that same measurement is not accurate. Wrong conclusion based on accurate measurement.

We have many means of measurement: our senses and our machines. Let’s be cautious in our proclamations based on our measurements.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

Life beyond 20kHz

“At least one member of each instrument family (strings, woodwinds, brass and percussion) produces energy to 40 kHz or above, and the spectra of some instruments extend beyond 100 kHz. Harmonics of muted trumpet extend to 80 kHz; violin and oboe, to above 40 kHz; and a cymbal crash was still strong at 100 kHz.”
Studies show we cannot hear beyond 20 kHz, most of us less than that. Yet we recognize higher sample rates sound better – and higher means higher than we can hear – which the measurementists claim is poppycock. But, what if we can hear above 20kHz? Might that explain some of why we like extended bandwidth equipment?
James Boyk, of the Caltech Music Lab (yeah – I thought they only did spaceships too) wrote a fascinating paper entitled There’s Life Above 20 kHz .

Given the existence of musical-instrument energy above 20 kilohertz, it is natural to ask whether the energy matters to human perception or music recording. The common view is that energy above 20 kHz does not matter, but AES preprint 3207 by Oohashi et al. claims that reproduced sound above 26 kHz “induces activation of alpha-EEG (electroencephalogram) rhythms that persist in the absence of high frequency stimulation, and can affect perception of sound quality.”

Oohashi and his colleagues recorded gamelan to a bandwidth of 60 kHz, and played back the recording to listeners through a speaker system with an extra tweeter for the range above 26 kHz. This tweeter was driven by its own amplifier, and the 26 kHz electronic crossover before the amplifier used steep filters. The experimenters found that the listeners’ EEGs and their subjective ratings of the sound quality were affected by whether this “ultra-tweeter” was on or off, even though the listeners explicitly denied that the reproduced sound was affected by the ultra-tweeter, and also denied, when presented with the ultrasonics alone, that any sound at all was being played.

From the fact that changes in subjects’ EEGs “persist in the absence of high frequency stimulation,” Oohashi and his colleagues infer that in audio comparisons, a substantial silent period is required between successive samples to avoid the second evaluation’s being corrupted by “hangover” of reaction to the first.

Boyk’s own conclusion suggest that if true, and there seems ample evidence it might be, then hard filtering everything above 20 kHz, as in a CD, might just be the worst thing we can do – and explain much about why higher sample rates makes sense, even though we can’t technically hear above them.

It’s just one more possible nail in the coffin of the measurementists who steadfastly refuse to recognize what many of us perceive just might be right.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

Judge and jury

We’re all judges. We choose what we eat, wear, watch and listen to.

And, even if we rely on the opinions of others to help us make those calls, in the end, we have chosen those we rely upon for help. There’s simply no escape from the fact that we all make judgements.
It’s often difficult to take responsibility for our judgments–easier to point a finger here or there. How many times have I asked a customer why they made this decision or that and the scramble to insulate from blame begins?

The problem for me is simple. I sometimes question people’s judgment in equipment choices, not because I want to be critical, but so I can better help them with their choices. Vinyl guys, tube guys, horn speaker guys, analytical types, emotional types. Understanding someone’s biases helps us all further the cause of great music reproduced in the home.

Yet, I understand one’s hesitation answering pointed questions on judgments. I still shrink from the memory of my father’s furrowed brow. “What the hell were you thinking?”

It is always refreshing to get a letter from someone who is clear about the reasons for their choices and willingness to express them.
“I followed the advice of this reviewer.”
“I love the look of horns.”
“It just sounds better!”

We should all feel a little pride in our decisions and the judgments we make, even if they might result in a few scoffs and rolling of the eyes.

After all, our decisions are like our children, for better or for worse.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

Target practice

It is common in some circles to target products to specific audiences.

Horror or action films, sports cars, solid state radios with visible tubes. Some succeed, most have limited appeal.

It’s been my experience that when a designer builds a product to a target audience, appealing to that audience becomes more important than the product itself. You’ve seen it all too often.

Formulaic films, overly sweetened desserts, audio products with lots of bass, or warmth, or over-teched detail, and little musicality.

The danger with narrowly targeting a product is you might succeed.

My advice to young designers has been consistent. Honor your own vision of perfection and success will follow. Build audio products that are true to the music, not to what you believe people might want to hear.

It’s why great products usually come out of nowhere.

The struggling artist, the overnight success.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

The placebo effect

When drug companies test new products they use control groups and placebos: ineffective drugs that test whether there is a difference between the real drug and a sugar pill. The results are often surprising.

The problem with placebos is we are not entirely machines.

Certainly we are biological beings whose many responses to stimuli can be predicted: eat too much and we get fat, smoke cigarettes and they’ll likely kill you, good diet and exercise make us feel better. But those are simplistic examples that do not take into account our higher order control. Some call it mind over matter.

There are numerous examples of changed behavior when a person’s belief is strong enough. We’ve all heard the stories and felt the effects. I’d be hesitant to discount the impact placebos have, yet there is a danger when it comes to audio systems.

If we want something to sound better we’re likely to convince ourselves it does. And we hear it! But, over time, the so called improvement we so hoped for fades if it is only a placebo. Which is one good reason to go back and retest your assumptions to clear the hope from the reality.

I remember well my experience with small Audiophile dots placed on various pieces of equipment for better sound. I was convinced they could not work, my BS alarm on high. And yet. I bought into the enthusiasm of the person selling me and became convinced of their efficacy. Once the glow of emotional expectations had worn off, the dots did nothing. They had lost their magic. I was told they had outlived their usefulness and needed to be replaced with new ones.
I knew better.

There are, without question, sonic improvements to be made. Lasting changes that stand the test of time.

Don’t be afraid to test your conclusions once the excitement of the new has faded into reality.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

Who said…?

….that anyone has yet devised a measurement system to predict whether a film will be a hit or a flop?

….that anyone can say for sure how a new car will feel when customers get behind the wheel?

….that machines can gauge how a product will sound?

We haven’t any way to judge emotional responses by using machines or clever data mining. And it’s not like we aren’t trying.

Just ask the political pollsters scrambling to keep up with our presidential race and its unexpected twists and turns.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

Audio myths, the last

It’s important to save the best for last.

Myth: Replacing the resistors and capacitors in preamps and power amps with higher quality units can improve the sound of a system.

Fact: Unless your capacitors are defective (they allow DC current to pass through them), or have changed their value over time due to heat and other environmental factors, you are not likely to improve anything by replacing them. The same goes for replacement metal film resistors. It’s true that metal film resistors have lower noise than other types, but that makes a difference only in certain critical circuits, such as the input stage of a high-gain mike preamp. It’s also true that different types of capacitors are more or less suitable for different types of circuits. But if you think the designers of your amplifier or mixer are too stupid to have used appropriate components in the first place, why would the rest of the design be good enough to warrant the cost of improved parts? In fairness, extremely old gear often employs carbon composition resistors, and replacing them can make a difference in many audio circuits. But anything manufactured in the past 20 years or so will use carbon film resistors and decent capacitors.

Yee haw! So our friend Ethan, who, BTW, is a very smart, experienced and knowledgeable fellow, suggests that if I were to use a 1mF $0.34 electrolytic capacitor, vs. a $10 1mF Film and Foil Rel Cap on the input of a high performance preamp or power amp, we’d hear no difference?

Really? I can tell you from personal experience this is simply untrue. It may be true that the author of the original post cannot hear a difference, but I assure you most people reading this blog would pick it out in a matter of seconds.

If it were not true, then we’d be idiots to use the $1.00 each PRP resistors and $10 Rel Caps in our designs. We’d be money ahead by simply using good old carbon film resistors, electrolytic or cheap film capacitors in the signal path. If it were a matter of perceived value, we could pot the whole mess and claim there was “secret sauce” inside. Instead, we just use the best sounding parts we can manage – and they are chosen for their sonic attributes by (gasp) people who listen.

And I can already read the response to this. “Prove it! Because my measurements show there to be no difference.” A reasonable response since it can be shown through the limited tests we engineers routinely perform, that there are no differences. And this is where the problem lies.

When we use limited testing methods to “prove” something, it doesn’t suggest what we hear isn’t valid if those limited tests don’t reveal any differences. In fact, we know (and Ethan should know too) that simple sine wave, THD, IM, and impulse response testing barely scratch the surface of what makes one product sound differently than the other.

The only test I have ever seen that came even remotely close to displaying differences was Bob Carver’s null test between two amplifiers. Using a sensitive differential scope and meter setup, two gain matched power amplifiers were fed the same musical signal. The differences between the two were immediately obvious. Bob was able to tweak his amp to more closely match the other and the two sounded very much closer after he did that (though not identical).

It is important to remember that between the two schools of thought: if it can’t be measured it doesn’t exist, and, if you can hear it it is real, there’s the truth of the matter.

We do not know how to measure all that we hear, just as physicists can’t explain all that they see.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

Audio myth 5

Myth: Amplifiers based on vacuum tubes sound better than solid state designs, and a good tube preamp can even restore clarity and warmth that has been lost in the digital recording process.

Fact: Both types of amplifiers can have a frequency response flat enough for audio reproduction. But modern solid state amplifiers have measurably lower distortion than any tube-based design. Most tube-based power amplifiers also require an output transformer, which increases distortion – especially at the frequency extremes.

Further, solid state power amps always have a better damping factor.

Many people – including me – like the sound of tubes, especially in a good guitar amp.

Even if you prefer the sound of tubes, please understand they simply cannot restore any quality that was lost earlier in the recording process. All a tube preamp can do is add an effect that you may find pleasing. Studio monitor amplifiers should never have a “sound;” if they do, they are in error. Tube circuits can affect the sound in a way that is similar to analog tape recorders, and you may in fact find that pleasing. I won’t dispute that even-order distortion can sound good, by adding overtones that are richer than odd-order distortion, which is, musically speaking, dissonant fifths. However, all distortion adds intermodulation (IM) products that are not harmonically related to the source material, and are thus decidedly non-musical.

As we have come to learn with Ethan’s posts, there is much truth in what he writes, though the conclusions based on those truths are sometimes suspect–occasionally just wrong. Let’s take a look at several of these often believed quotations.

“Studio monitor amplifiers should never have a “sound;” if they do, they are in error.” Well, that’s nice to say and makes sense. Only, it’s inaccurate. All amplifiers impart a sonic signature; some more, some less–as do the other tools of recording engineers, from microphones to loudspeakers. Of course the ideal would always be to use amplifiers, microphones, monitors, wiring and recording apparatus that are sonically neutral. The problem is, they do not exist.

“…tube amps simply cannot restore any quality that was lost earlier in the recording process. All a tube preamp can do is add an effect that you may find pleasing.” This is a very common myth – and a carefully written one at that. The author is 100% correct that nothing can restore that which has been lost. It is for this very reason we cannot restore MP3 and lossy files to their original splendor. Once lost, forever gone. But it is to the second sentence where we have our differences.

“All a tube preamp can do is add an effect that you may find pleasing.” Poppycock. I have numerous examples of circuitry, both tube and solid state, that hide information less than other configurations. And this is a point I try to help people understand. Great circuitry does not bring out more information, instead, it hides it less. And therein lies a big difference.

I recall the first time I listened to DirectStream playback a CD. One of my coworkers mistook the playback for high resolution (we had both a CD and high resolution copy on the server of that track). He was right! For the first time, it was evident the gap between CD and high resolution audio had been nearly closed–and not because DirectStream revealed more–but because DirectStream hid less.

So, the next time you listen to kit that uncovers missing details, remind yourself that your previous reference had been hiding it, not the opposite.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

Audio myth 4

Myth: Using audiophile speaker cables improves the sound, compared to an equally heavy gauge of normal electrical wire.

Fact: The most important feature speaker wire can possess is low resistance at audio frequencies. The makers of expensive audiophile speaker cable claim their products are better because they have a frequency capability that extends into the MHz range. But there is no evidence that wire capable of carrying frequencies many times higher than what it will actually carry is useful or worth the extra money.

The only truly negative effects you could attribute to speaker cable are too high a resistance (which affects an amplifier’s damping factor), and high frequency losses due to cable inductance and capacitance. But you would need a long cable length before the reactive components (inductance and capacitance) affect anything within the audio range. So, while low-resistance wiring is clearly important (for the damping factor), nearly any sufficiently heavy wire will suffice for a speaker cable in the lengths used by most recording studios. Heavy gauge zip cord is ideal for runs of twenty feet or less, and it’s readily available in #14 and even thicker gauges (my edits reduced the number of words in the original post).
While I have agreed with most of what Ethan’s posts suggest so far, I will have to take a stand on this one. “Heavy gauge zip cord is ideal for runs of twenty feet or less..” them’s fightin’ words!

I know this rankles those who cannot explain why using only test equipment, and therefore it must not be true, but reality is very different from what has been written here. If, by “ideal“, the author means the speaker/amplifier combination performs as expected on a test bench, then we are in agreement. If, by “ideal“, he means there would be no sonic differences between heavy gauge zip cord and a decently designed speaker cable, then I would suggest the following possibilities: he has not actually compared the two, the reference system does not possess sufficient resolving power to hear the differences, he does not know what to listen for, or he believes test results over ears.

Whatever the case, the differences between zip cord and well designed speaker cables are huge, sonically obvious on most systems, and covered in great depth by these very posts. In fact, this statement is so wrong I don’t think it is worth a lot of time to debunk it. And here is why.

We each see the world through individual biases, or lenses. The author I am quoting sees the world through the lens of his test equipment and finds it easy to justify his position using those tools. My lens is my ears and I observe something very different because of it.

Each of us believes we’re right and the other person simply misses the point. I can easily prove my observation to anyone showing up at my front door. Ethan can prove his by displaying irrefutable numbers. Who is right? Undoubtedly we’re both right in our somewhat myopic observations; not necessarily in our conclusions.

If you’d like to watch an interesting video sent to me by a reader, click here to see how biases distort our world view.