Tag Archives: Mark Levinson

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.

Last but not least

Following the past few day’s posts about audio amplifier efficiency, Class AB biasing, and Class A biasing, let’s wrap our little mini-series up with another topology most of us have not heard of, adaptive biasing.

The promise of adaptive biasing is a best of both worlds scenario: the efficiency of a Class AB circuit with the performance of a Class A amp. Sounds too good to be true, right?

The first time I ever heard about an adaptive biasing scheme was way back in the dark ages, the late 1970s. My very dear friend and one of the all-time good guys of audio, Nelson Pass, then of Threshold Corporation, had introduced the idea of what we called a sliding bias scheme, part of what later became known as the Stasis Circuit used in Nakamichi, Threshold and if memory serves correctly, even the Mark Levinson No. 33.

The core of this circuitry is covered in Nelson’s patent from 1975 titled Active bias circuit for operating push-pull amplifiers in class A mode.

Simply put, Nelson’s design raises the level of Class A bias in cadence with the rising input signal.

Recall in our discussion of Class AB design that a small amount of always-on power keeps small signals always on. In other words, we apply Class A (always-on) bias to the first 10% of the amplifiers output signal level, then switch over to the more efficient Class B for higher signals. Compare that to Class A operation which is always-on for any level of signal—always generating a shit-ton worth of heat (recall Class A amps are at their coolest when at full signal out).

What Nelson cleverly suggested was this. Take what we do in an AB amp where the first 10% of the signal is Class A and actively monitor the signal level. When any given input signal starts to exceed our 10% Class A bias, raise the limit from 10% to, say, 20% (or whatever is greater than the signal level), and continue on the path all the way up to 100%. Then back down again tracking the signal. The heat-producing bias is only enough to accommodate the signal, then goes away when it’s not needed.

Thus, we get the benefits of both worlds. Efficient, and sweet-sounding.

Why doesn’t every amp use this even today? (Nelson’s patents ran their course years ago). Well, as with any design there are problems as well as advantages and this post is long enough already. Ain’t nuthin’ perfect. (We used this for several models of amps though their model numbers and dates escape me).

In any case, a juicy piece of history I’d thought I would share.

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 trouble with convention

I remember my excitement when Mark Levinson’s company broke with the pack and started building products with Lemo Connectors. Wow. Those were wicked cool looking and they had an even cooler story behind them too. Alas, this trend never caught on because nothing else matched and who wants to use adapters?

Then, Arnie and I chose to use Neutrik Speakons for our Genesis I system’s subwoofer connecting cables. These cool multiwire connectors were vetted in the pro-industry and accepted as not only easy to use but made certain our woofers, with their built-in accelerometers, could never be connected in error. Brilliant, yet, today there’s nary a product I am aware of in high-end land using them. (Turns out that after using them over the years they’re pretty cheaply made and not all that robust).

And, I remember when Wisconsin based Wadia, then the hot ticket in digital audio, built their products around ATT glass fiber that could easily handle gigahertz and was the be all to end all (it was then and still is now). That connector was eclipsed with the very much worse plastic POS released from Toshiba called TOS/LINK (Toshiba Link). It’s a rare day when that can get close to high-resolution audio.

And so today none of these attempts at bettering performance through advanced tech remain because convention has sucked the life out of them—mashed by the steamroller of mediocrity, leaving those of us wishing better to come up with hacks, like our use of HDMI for I2S.

Indeed, our penchant for conformity leaves those of us desirous of great performance heights out in the cold.

The good news of convention is it plays nice with everything.

The bad news is it plays nice with everything.

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.

Mark Levinson is a guy who sold his name  and has been described as….err….challenging to work with. Yet he has carved out a niche for himself in high end audio, that has lasted around 40 years now. More than anything, he is a salesman, but perhaps not such a great business partner.  If they were still around, ask Sandy Berlin and Mike Kay about that and it would surely have been a story. God bless him, Mike Kay lost money with Levinson the person, twice.

Mark Levinson, Wadia, Cello

Mark Levinson started his company, Mark Levinson Audio Systems (MLAS), in 1972, two years before the founding of PS Audio. Mark was the company visionary while a parade of engineers including John Curl, Dick Burwen, and Tom Colangelo designed the products. Like many garage-based operations, MLAS loped along until investors Mike Kay (Lyric HiFi) and Sandy Berlin (Harman) came to the rescue.

But even after an infusion of cash, MLAS struggled before vaulting itself into the iconic status the company once enjoyed in its prime.

Instrumental in the meteoric rise of MLAS was their director of sales, Jim McCullough, a man whose chief qualification for selling high-end audio was that he’d read a few magazines and owned MLAS equipment. In five short years MLAS went from near-nothing to $10,000,000 before McCullough left for Wadia, where he managed to do it again: From nothing to $10,000,000 in five years. And then, it was on to Mark Levinson’s (the man) new company, Cello.

Of course, no one man can take all the credit for a company’s success. But one thing Jim McCullough can do is playback a wealth of great stories of how it all happened. And those stories and history are a hoot, well worth the time to listen.

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 use EQ..I use EQ…Use EQ…But, they aren’t all the same..LOL

Purist controls

We’re purists, right? We seek to clear the clutter, end the distortion, cut through the haze, and get to the musical truth.

It’s why we don’t like audio tone controls or, for that matter, anything not focused on purity—except when the unpure is packaged as perfectionist.

I remember when Mark Levinson’s second company Cello launched the Audio Palette, itself a tone control. But it was expensive, in a beautiful chassis, and helped remove the stigma associated with tone controls.

Times change. In defense of tone controls, they were needed when they were introduced. ‘Back in the day’ speaker systems and recordings were so lacking in frequency extremes that a small boost or cut in the upper or lower areas made sense.

I’ve recorded a podcast on the subject you can listen to here. If you’d like to subscribe you can get it on your iPhone or iPad by going here. Just click on the button “View in iTunes” below the Ohm’s Law picture of me. If you have an Android phone or tablet, go here to subscribe. Or, if you prefer to listen on the webpage, all the available podcasts are here.

This Saturday I am posting my interview with the late Arnie Nudell. The following Saturday, my interview with Elton John, and the Saturday after that Steve Mariott and Humble Pie. More interviews each week. I’d appreciate it if you’d subscribe, leave some feedback, and tell a friend.

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.

In this post, Paul talks about brands and what they mean, or maybe what they used to mean.

As companies get bought and sold to larger conglomerates, things usually don’t get better, especially in high end audio. See Altec, Urei, Advent, JBL, Mark Levinson, Krell and a host of other high end audio companies. Some, like Audio Research, Sonus Faber and REL might be better, but I’m not sure about that.
What happens to brands?

Brands come and go, just like people. And, like people, they have personalities reflecting their raison d’être.

Most brands are formed by entrepreneurs passionate enough about something to take a chance and put everything on the line for it.

But, at some point, these brands can become commodities, bought and sold like a head of lettuce. When that happens they lose their original soul and become something entirely different. That’s not necessarily bad, though it’s almost never the same.

Take JBL for example. The first pair of high-end loudspeakers I ever heard were a pair of JBL corner horns. So good were these sonic wonders it changed the course of my life forever. Yet, go find a pair of new JBL home speakers you could say the same about today.

Millions of musicians and car owners know a different JBL than the one I grew up with, and appreciate it on an entirely different level. Or hate it.

Brands represent their owner’s purpose. Wally Amos wanted to impress friends with the quality of his Famous Amos cookies; I am certain they were pretty tasty.

The current owner of Famous Amos cookies, Kellogs, is more interested in numbers than quality or taste; and their product reflects this.

When you’re interested in buying into a brand, look behind the curtain to see who is pulling the levers.

 

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.

Back to Paul later, as he is writing about something similar in subject matter, to what I have been going on about the last few days.

My first Audio-Bam-Bam music experience  was in an Oxford College dorm listening to a friends (Scotty Yates) Dynaco tube amplifier and some bad sounding orange colored PA horn speakers, with subwoofers. No imaging and bright, but boy did it play loudly. And, as Paul mentions, there was probably hash/pot and other stuff involved here too, so most probably the loud part is what got me.

The first truly great sounding stereo system I heard, was at Scotty’s apartment in Atlanta in the early 70’s and consisted of his tubed Dynaco amp and preamp, which he built from kits, and a pair of JBL L-100 loudspeakers. I could hear stuff that I never knew existed on our records and was blown away by that, as well the imaging his system created, as this was the first time I couldn’t localize the loudspeakers. I knew then that I wanted a great stereo system one day.

The first truly incredible system I heard was  in the mid 70″s, at a high end audio store called Sound Components in Coral Gables, Fl. I believe they are still around, although owned by someone different now. Back then, the store was owned by Peter McGrath and Peter did, and still does, know how to make great audio. He now works for Wilson Audio and records Classical music. Six foot tall Wilson Wamm’s (I believe) were the speakers, they were huge and cost over $100,000 over 30 years ago. I believe the electronics were Mark Levinson, which is now owned by Harmon Intl. and were the best at the time. Not so much anymore, although Mark Levinson, the person, is still building audio stuff in Switzerland and selling under the Daniel Herz badge. Levinson’s Herz speakers are very similar in concept to what I have built, using a combination of a horn and a dynamic midrange/woofer.

This system was as dynamic as real music, as clear as the recordings would permit and probably imaged even better than what I have now. However, tonally, I didn’t like it much as it basically sounded bright, but the other attributes of the system were mind blowing.

I wanted to get to that Sound Components experience, with a smaller budget and different sounding, and in most important ways, I have done that, but at a fraction of the price and by building my own loudspeakers.

Take it away, Paul…

Our first one

Each of us remembers our first love affair, puppy, day at school.

What was your first encounter with high end audio? What was the first track you heard on a great, resolving, three-dimensional stereo system?

I remember mine well.

It was 1974, the system was owned by a local merchant and “audio nut” named Norm Little. Norm had a tri-amped Audio Research system driving a pair of Cerwin Vega 18″ woofers, a set of Jantzen electrostats, and tweeters I cannot remember ever paying attention to. The preamp was also Audio Research, SP3A4. I don’t remember the turntable but I do remember the arm, a Rabco straight tracker, the cartridge from Decca.

And Norm had a freezer full of hash. It was the 70’s, after all.

He played for me Stevie Wonder’s Living For The City and I think I may have been drooling—which happens when you can’t pick your jaw up from the floor.

In front of me was an image! A sonic picture, the city, instruments separated and placed within a magic tapestry with clear locations from front to back, side to side, as if they might be playing in the same room.

This was a revelation to me, soon followed by yet another similar experience on an entirely different system, but of lesser magnitude.

Like the first time in a fast car, a pretty girl, holding your newborn—trying to keep tears from falling.

There’s only one first for all new experiences in our lives.

What was yours?

 

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.

DSP: Analog signal processors

Before we jump into DSP (Digital Signal Processors) let’s start by understanding their forebearers: ASP (Analog Signal Processors).

The simplest ASP you’re likely familiar with is a tone control, like a bass and treble set. Long ago, all stereo amplifiers and preamplifiers had tone controls. Tone controls were typically used to boost either the bass or the treble–or both–for recordings and loudspeakers. As the hi-fi industry grew, simple tone controls turned into complex graphic equalizers. Here’s a picture of a popular Soundcraftsmen from years ago.

These complex controls offered greater flexibility tuning the system, as well as the room, and had become part of the natural landscape of consumer audio–though not too many Audiophiles embraced them because of damage to the sound. Running through groups of op amps and filters isn’t exactly the purist’s path. Add in massive phase shift when the tone controls are engaged, and what you gained in smooth amplitude was at the expense of good sound.

However, Audiophiles did embrace a graphic equalizer at one time, the much coveted Cello Audio Palette. Here’s a picture of it.

Envisioned by Mark Levinson (the man) and designed by Dick Burwen (the engineer) the Audio Palette was blessed by the Audiophile community. It was functionally the same product as the Soundcraftsmen, but sounded much better because of the skill of the designer.

Asheville, North Carolina ‘s Home Theater and Audio specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Harebrained schemes

We’ve been discussing why we and other manufacturers don’t build regenerators into our equipment. Real estate and expense is certainly one of the biggest reasons. But one of my readers correctly pointed out we actually did build a regenerator into one of our products and I think I remember Mark Levinson (the company, not the man), did as well. If my memory serves, the Levinson 33H monoblock and the PS Audio Classic 250 had regenerators built into them. They were both physically large beasts.

In the case of the Classic 250 the regenerator powered only the amplifier’s front end, not the power output stage. The Levinson, I believe, enjoyed regenerated power for both. It also stood nearly two feet tall and weighed 220 pounds. Most of the weight and expense of that amplifier was in the power supply and case work.

But did I ever tell you about the very first regenerator I designed? Remember, this is back in the late 1990′s when no power conditioning category existed in the high end. Taking care of the AC was a relatively foreign concept. There was the MIT stabilizer, the Tice Power Blocks and not much else. I wanted to set the world straight on the importance of proper AC and devised a clever way to do it.

I knew it was impossible to filter the problems of AC power: fluctuating voltage levels, flat topped sine waves, misshapen sine waves, shared connections with your neighbors. My first thought? Build your own power generating station in the backyard and remove your home from the grid. Ok, that’s probably not a practical approach, even for an admitted lunatic. Second best? A motor and a generator. I could use an AC motor to spin a generator and an electronic servo system to regulate the speed of the motor producing steady, perfect, isolated AC power to my system. It wouldn’t matter what evil my neighbors were up to in their homes, I would essentially be isolated from the grid with this scheme. It seemed a rather brilliant solution to a big problem few in our industry were addressing.

There was only one major fly in the ointment of this scheme, which I will cover tomorrow.

Climbing the ladder

Back in the dawn of time for digital audio, the 1980′s through the 1990′s, there was basically only one type of DAC architecture in popular use: the ladder DAC.  As well, the mainstay of the ADC (the recording end of things) was also a similar arrangement.

These were the classic PCM based systems we all got involved in digital audio with.  They could handle the 44.1kHz/16 bit requirements of the CD with appropriate accuracy and life was good.  The sound wasn’t so good, but life was.

It didn’t take long before the quest for better, faster and more bits started to rear its head.  One of the first indications of this came from a company called Ultra Analog out of the Bay Area.  Ultra Analog was a very technologically advanced company and they had a better, more accurate version of the classic ladder DAC.  Many of you may remember that many, many high end DACS of the day started using their proprietary DAC modules including: Audio Research, Sonic Frontiers, Mark Levinson, Threshold and yes, PS Audio.  The main selling point of this DAC is it featured true 20 bit performance.  This was no easy task given the architecture of the day.  Here’s a photo of an Ultra Analog module.

Ultra analog 300x225 Climbing the ladder

So popular was this product that PS Audio based all our DAC products around the modules (producing the Ultralink DAC) and eventually we even bought the company, Ultra Analog, so popular were these models.  That was a long time ago.

That DAC technology depended on having extremely accurate resistors.  In fact, so accurate, that Ultra Analog’s secret wasn’t in using resistor’s that were more accurate than anyone else’s (they couldn’t because we’d reached the theoretical limit on accuracy).  Instead, clever engineering and a bag full of tricks did the job.  But that job of increasing the number of bits was at its very limit – one pushed to the extreme by this very DAC module, used in so many fine DACS of the day.

Yet today 24 and even 32 bit DACS are everywhere.  These everyday DACS have performance so much better than the 20-bit Ultra Link module that the engineers of that period would have cried “impossible”!  No one seems to have noticed just how much has changed since the days of Ultra Analog’s miracle 20 bit wonder – changes we seem to take for granted.  Using the classic ladder DAC architecture, each added bit is exponentially more difficult to achieve than the last.

What changed?  Did we solve the problem of the ladder DAC or did something else happen?


Paul McGowan – PS Audio Intl.