Tag Archives: preamplifier

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

This is interesting to me because of the plethora of really expensive audio equipment available today and made all over the world, that is what many in the stereo world refer to as “eye candy”. Much of this looks beautiful, in many different ways, and that is indeed, pleasing to look at.

As long as I’ve been paying attention, high end audio has always had its share of bizarre looking stereo gear, but today you have some gear that is super expensive and have the looks to match. Nothing wrong with that if people want to buy it and it sounds good enough for them, but if you care about sound quality first, the eye candy doesn’t always deliver the goods.

Right now, I use nothing that is over the top in terms of looks and in fact, I’m using a puny, but pleasant looking  T+A Amp 8 amplifier with all of 80 watts per channel into 8 ohms. It’s certainly not over the top looks wise and in fact, looks kind of funny on my Zoethecus amplifier stand, which has held 100 lbs. + beasts before. It is a 15 lb., 11″x11″x4″ Class A/B stereo amplifier and it is driving my beautiful, but very large and heavy, homemade Altec 604 based loudspeakers, which each weigh probably close to 150 lbs. each and are largely proportioned, although beautiful and sleek.

With my various loudspeakers, including the Daedalus Ulysses V2 speakers I’ve also used, which also have high sensitivity, but are harder to drive because of impedance, it’s plenty powerful for these speakers. In fact, the amp gets barely warm driving my Altec’s at very high listening levels, but never hot because the speakers are so easy to drive. Because of the more complex crossover of the Daedalus speakers, they can still be driven to full volume, but the amp has to work harder, so gets pretty warm.

I use the Amp 8 because in combination with a couple preamps I have on hand, my loudspeakers sound wonderful driven by this small amplifier. And, it’s not a Class  D amp, but a traditional, although unique, Class AB amp.

Eye candy? Hardly, but not ugly and makes beautiful wounding music and that’s #1 in my book

Pretty faces

We all love a pretty face.

Pretty faces can take any number of forms, like for example, the front panel of a piece of stereo gear. You’re either attracted or repulsed by the unit’s look.

Hopefully, you’re attracted.

When we design a new piece of stereo equipment, whether it’s a loudspeaker or a preamplifier, looks matter greatly. Not only is it important to be appealing to the eye, but the look of any product should also tell a story about what’s inside and what to expect.

Like a bright, shiny, sleek automobile. Its appearance language suggests it’s ready to go fast, or to be super comfortable, or perhaps luxurious.

The same is true for our stereo products.

A big power amplifier should look the part: brawny, heavy, powerful. A preamplifier should beg to be touched.

If the insides and audio performance match that of the unit’s outward appearance, we’re happy.

We all love a pretty face.

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

While I’m now using almost all solid state stereo equipment, except for a Rogue RP-7, which is a hybrid tube/solid state preamplifier I keep around because of its wonderful headphone amplifier, I’ve owned a lot of tube gear and this is a great explanation of how tubes work.

These days vacuum tubes are primarily made in Russia, China, The Czech Republic and even a 300B power triode is apparently made here in the USA by a newly formulated Western Electric, an iconic brand from the past.

The war in Ukraine has made some of the more unique Russian power tubes, like the KT 120, KT 150 and KT 170’s getting scarce. Too bad as this is the single source for these high power pentode tubes.  Fortunately, the JJ company out of the Czech Republic makes excellent substitutes which aren’t quite as powerful as the Tungsol Russian tubes, but powerful enough, they sound great and are reliable..

Glowing tubes

Peering down inside of a BHK preamp the other day, I was rewarded with the warm rosy glow of its vacuum tubes.

And I was reminded how similar a vacuum tube is to a lightbulb (I know. I am weird).

Both vacuum tubes and lightbulbs have glass envelopes that keep the outside air from getting in. And both vacuum tubes and lightbulbs have filaments that produce both light and heat.

So, where do they differ and why?

A light bulb filament is made of a thin wire, typically tungsten, that is coiled or twisted to maximize its surface area. When an electric current is passed through the filament, the resistance of the wire causes it to heat up to a very high temperature, around 2500°C. At such a high temperature, the tungsten filament glows white-hot and produces visible light.

A vacuum tube filament, on the other hand, is designed to emit electrons rather than light. The material of the filament is often similar to a lightbulb—a slightly modified version based on tungsten—but instead of getting white hot and emitting a bright light, a vacuum tube’s filament is cooler, typically around 700-800°C. At this lower temperature, the filament emits a small glow of light, but, more importantly, electrons boil off of its surface in a process called thermionic emission.

With an abundance of electrons coming off of the filament (cathode), we now have the fuel we need to have our vacuum tube work its audio magic. Basically, we need a way to control how many of these generated electrons are put to work, and we need to give them a place to go.

Of the three elements that make up a vacuum tube like the venerable 12AX7—cathode, grid, anode—the grid controls how many of the electrons are being put to work, and the anode (plate) provides the means for attracting them.

Your audio signal is connected up to the grid. The louder the audio signal, the more electrons are encouraged to head to the plate (the tube’s output) and we get a bigger signal.

It all starts with that rosy glow from the filament.

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

We’re not even close

Part of the joy and privilege of being involved in both the recording and playback chains is the chance to grow and learn: new methods in recordings of miking and capturing sound and, in the reproduction chain, new circuit topologies and silicon.

Recently a fellow recording engineer working with the same basic DSD chain suggested to me that using an external microphone preamplifier before going into the A/D converter is probably a bad idea. Why? Because it is thought that the particular A/D converters we both use (from Pyramix) are better served skipping a step and going directly in. That made one heck of a lot of sense to me, and so, on a recent recording session of Octave’s beautiful Steinway piano by composer and pianist, Gustaf Hoyer, I recorded it both ways: directly in and with the addition of an external microphone preamplifier.

Oh my. The difference between those two methods is stark.

Using the identical microphones and setup for both:

  1. Going directly into the A/D converter’s built in microphone stage left me cold. Unmoved. Mechanical. Clear and crisp, yes. But without life or feeling.
  2. Inserting in the same path the Manley vacuum tube microphone preamplifiers between the microphones and A/D direct inputs. Holy sh*t! Life! Musicality. Openness. You are there. Still clear and crisp.

And here’s the crazy thing. When in Pyramix you switch between microphone and line level inputs, the electronic chain remains identical. In other words all that changes is the impedance and gain of the input stage. Same circuitry with only a 20dB pad inserted.

This is absolutely bizarre and makes no sense to me. It reminds me of when I used to be an advocate of the shorter path of DAC->power amplifier. Inserting the BHK preamp (DAC->BHK preamp->power amp) made magic.

Other than just reporting this observation, my only thought is that my friend must not have used the same microphone preamplifiers.

The good news is twofold: first, all recent Octave recordings (and many earlier ones) have used the Manley’s for preamplification. Second, while we always take suggestions and are anxious to experiment, in the end, our ears tell us what works and what does not.

As my hero, Mr. Spock might say, fascinating.

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

Fast and slow

After 50 years of working with audio gear, it’s easy for me to forget not everyone knows the basics. I’ll do my best to help remedy that.

A few days ago we got into fuses, a subject that helped me realize not everyone knows there are two basic types. Fast and slow.

A fast fuse saves circuitry. A slow fuse saves lives.

First, let’s talk fast blo fuses. You don’t see these a lot anymore. They are typically used in the DC “rails” (the power supplies) that feed circuitry. They need to be quick because they are there to stop the voltage feeding circuitry before something bad happens to that circuitry. Their most common use is to protect power transistors in the output of a power amplifier. Where small signal circuitry like that of a preamplifier doesn’t have enough “juice” behind it to cause damage to the silicon, a power amplifier surely does. The fuse must die faster than the transistor it is protecting.

A fast blo fuse is basically a whisker-thin wire inside a glass (or ceramic) enclosure. Here’s a picture of one.

Fuses are designed into the power supplies that feed the output transistors of amplifiers. They are chosen by their rating of how much power they can pass before the little wire inside heats up and vaporizes—thus breaking the connection to the power supply.

Most amplifiers don’t have these because there are now more modern means of providing the quick shut off (other solid state devices).

A slow blo fuse has the same characteristic as the fast blo, meaning it too is chosen by the maximum amount of current (power) that is allowed to pass through it. The difference is time.

When we first plug in a product to the AC wall socket, or flick on the power switch, a surge of power flows into the unit. Perhaps you’ve noticed the room lights dimming on first turn on of a power hungry something. This inrush of current (power) needed to fill empty power supply capacitors (or start a motor or heater) is only for a brief moment. Thus, what we want is a fuse that will tolerate that momentary inrush of power until the device settles down.

That’s why it’s called a slow blo. Here’s a picture of one:

Instead of the whisker-thin wire of the fast blo, we now have what looks kind of like a spring. Pass enough current for long enough through the spring and it too heats up and vaporizes.

Slow blo fuses are found at the very input of products. Before the power supply. They exist to make sure that your product doesn’t light on fire, or that the wires in your home don’t light on fire.

Of course, modern homes are doubly protected. An electromechanical version of the venerable fuse is required for safety. It is called a circuit breaker.

Hope that helps.

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

Technocrats and artists

When a design engineer tackles a new product there are a myriad of options available to them.

Take for example a preamplifier. Here the designer must choose the type of amplification topology: single ended or balanced, differential input or single gain device, direct coupled or capacitor, solid state or vacuum tube or hybrid. And once chosen there’s another bushel full of choices to be made, each resulting in a very different sound.

Or take the challenges presented to a loudspeaker designer. Number and types of drivers, open baffle, closed baffle, dipole, bipole, monopole.

Once the direction is chosen, there comes a divergence of workflow depending on whether the design engineer leans towards being a technocrat or an artist.

The technocrat worships the god of technology while the artist’s muse leans more toward serving their emotional side.

An analytical approach versus one more centered around the emotional side.

Mr. Spock vs. Picasso.

Our own philosophies at PS Audio have always been centered somewhere closer to middle ground.

Norman Rockwell.

As a consumer, you’ll want to decide which products on offer appeal more to your analytical or emotional side.

The fruits born of the labors of technocrats and artists sound very different indeed.

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

I don’t use EQ the way Paul describes below, however I do use EQ on my home made Altec 604 GPA loudspeakers. Although I only use them in the band centered around 2k, it helps makes a great speaker sound even better. My EQ’s, which are UREI 539’s, only cut level, not add and this is actually the right way to do it!

Eq limitations

Equalization is the act of increasing or decreasing the amplitude (loudness) of specific ranges of frequencies.

The most common form of EQ was once the ubiquitous bass and treble controls found on consumer audio equipment. These knobs or sliders allowed one to reduce or increase the amounts of both frequency ranges. (in my experience they were almost always cranked up on high).

Today, a few brave souls are using EQ to help adjust low frequencies anomalies in the room—mostly with the addition of a low cost easy to use DSP product like the MiniDSP. For $100 this device can take the analog output from your preamplifier and be used to feed a separate bass amplifier in a bi-amped system. Once inserted between the preamplifier and woofer amplifier, a simple and intuitive user interface can be used to adjust the bass response of your woofer.

Any loudspeaker with separate binding posts for woofer and tweeter can enjoy the benefits of biamping and EQ control using this simple setup.

While I wouldn’t recommend trying this for anything other than a woofer, it can be helpful in smoothing out the peaks and bumps caused by room modes and standing waves.

While peaks and bumps are easy to eliminate fixing the dips and valleys caused by the room are almost always impossible to fix. That’s because the loss of bass frequencies in a room are caused by cancellation (just as peaks and bumps are caused by addition). And unfortunately, regardless of how much more loudness you pump into the system at those frequencies, the cancellations just keep doing their thing.

So, should you go down this EQ road, just be mindful the most valuable improvement you can hope for is the reduction of peak and boom, not the pickup of missing bass.

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

Impedance differences

If you double the input impedance of your power amplifier from, say, 30kΩ to 60kΩ you’re not going to hear a difference.

Yet, double the input impedance of your phono amplifier and you’ll hear a change.

What’s different between the two?

In the first case of the preamp feeding the amplifier, we won’t hear any difference because nothing in this chain affects frequency. The amp’s input impedance must be high enough to not load down the preamp, but aside from that, not much else matters.

That’s not true when it comes to a device such as a phono cartridge. Here the small coil generating the voltage feeding the phono preamplifier is part of what we refer to as a tank circuit—a tuned inductive network where the frequency response is a function of impedance and capacitance.

Think of it like a filter where the resulting output is dependent on the values of the elements that make up the network: coil, cap, resistor.

It is natural to assume that if the impedance setting of one element within our system matters, then it stands to reason all must.

Hopefully, it helps to have a short little explanation like this to set the record straight.

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

The price of scarcity

When something desirable is scarce its value increases.

It’s the old supply and demand theory we learned about in school. If more people want something than there is an available supply, the price adjusts upward.

Think of a vinyl album where only so many copies were pressed. Or, consider that only 58 pairs of IRSV speakers were ever made.

Scarcity can even apply to simpler things. Terri and I were skinning a bushel of our homegrown tomatoes last night. We turned those beauties into a delicious tomato sauce we’re going to freeze and sparingly consume over the winter months. No one else on the planet has the same tomato sauce as do we.

Thankfully, much of what we as audiophiles value with respect to new equipment isn’t scarce. You can grab a copy of a production DAC, integrated amplifier, or preamplifier without much worry about bickering over price. That’s not quite as true with vintage equipment.

What we can say about scarcity is that for most of us, the collection of hand-picked equipment, cables, room treatment, and careful placement is unique in all the world. Your stereo system in your room sounds different than mine because of the environment and the choices made to create that system.

What kind of price would you assign to your hand-built creation?

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

Can work either way..

Subwoofer connections

For more than three decades I have strongly advocated the high-level connection of subwoofers—where we connect the output of the power amplifier to the input of the subwoofer.

What amazes me is that still to this day, that viewpoint is considered radical.

The vast majority of subwoofer manufacturers would have you connecting their subwoofers through low-level inputs as supplied by your preamplifier. Their reasoning is simple. The output of a preamplifier is cleaner and more direct than what happens after a power amplifier has processed it.

My good friend, John Hunter of REL subs is one of the few subwoofer manufacturers agreeing with me.

And here’s the thing. The majority of subwoofer manufacturers are correct. There’s no argument that the output of the preamplifier is cleaner, purer, and more direct than the output of a power amplifier.

So why the debate?

Because they are missing the point. Subwoofers should not stand out in the system. The whole point of a subwoofer is to augment the performance of the main loudspeakers. We don’t want to hear the subwoofer. We want to pretend as if it were a perfect appendage to the main speakers. To make that happen we need to do whatever we can to get closer to matching the sound of the main speakers—a perfect pairing.

We want the characteristics of the power amp to color the output of our subwoofer in an effort to more closely integrate it.

Hope that helps.

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

Mechanical vs. solid state

When we need to switch inputs on an analog preamplifier we use a switch. The kind of switch we use affects stereo sound quality.

For years we had only mechanical switches from which to choose. Standard switch contacts in those days were nickel or tin-plated while the more expensive and better-sounding styles were either silver or gold.

These worked great and sounded excellent, but they had a problem. They were nearly impossible to remote control.

The customer’s desire to control their systems from their easy chairs drove us designers to replace mechanical switches with electromechanical relays. Relays were available with the same contact materials though because they weren’t self wiping (like mechanical rotary switches), their slap and connect operations produced a slight degradation in sound quality.

Relays are expensive and cumbersome.

Along came silicon switching. Low cost, quiet, reliable, and without the problems of contact degradation. Sonically, they fell into third place, but not too far behind relays.

Engineering is always a matter of compromise. We give up one thing and in exchange get something else.

In most of PS Audio’s PerfectWave series of analog audio products, we rely upon a combination of electromechanical and electronic switching.

Common sense, practical, excellent performance.