THE 12 MOST SIGNIFICANT PREAMPS OF ALL TIME!

the absolute soundGROUNDBREAKING!PASS LABS' NEW PREAMP

5>

ir+3-nQJa-tno

n>i/ioc3Q.Oo3

cz\)"3

SPECELECSSUE!

* 11 Preamp Si Amp̂gyiews* 9 Great DesignersDebate Amplifiers

* NAD's Digital Media Tuner

MINI-MAGGIEMagnepan's mostaffordable speaker yet!MUSIC FROM Lyle Lovett, Muddy Waters,Willie Nelson & Esperanza Spalding

PLUS! High-Res Download Reviews

AMPLIFIER DESIGNER ROUNDTABLEHow have amplifiers improved over the last decade? What is the state of audio amplificationtoday? Have tube sound and transistor sound become more alike? What innovations will thefuture bring?

To gain some insight into these and other issues, I posed the same set of questions to nineof the world's top amplifier designers. Each of these internationally recognized engineers hasproduced world-class preamplifiers and power amplifiers, and each takes a different approach tothe challenge of creating cutting-edge audio electronics-in some cases, radically so.

-Robert Harley

BOB CARVER/Bob Carver LLC JOHN CURL / Parasound, Constellation CYRILL HAMMER / Soulution

LEW JOHNSON / conrad-johnson design VLADIMIR LAMM / Lamm Industries FUMIO OHASHI / BAIabo

".'̂ yNELSON PASS/Pass Labs JURGEN REIS/M6L JEFF ROWLAND/Jeff Rowland Design

///////////////////m^^^theebsolotesouod May/June 2012 53

We are no longer interested in facsimile reproduction; rather wefind that reproduction that sounds enchanting and real is far moreinteresting and serves our passions far better.

mmm

■ received my undergraduate degree in physics from theUniversity of Washington and my Master's and an honoraryE Ph.D. from the University of British Colombia and the UW.I I started the Phase Linear Corporation in 1970 to build,

market, and sell my first invention, a 700 watt amplifier. Afterthat I started Carver Corporation followed by a small biotechnology company Carver Genetic Physics. Finally, I startedSunfire to build and sell my new invention, the high pressure,high back-EMF subwoofer. I successfully sold each company. Mymain inventions were the magnetic-field amp, the high-pressuresubwoofer, the asymmetrical FM detector, the DC restorer, thedipole woofer system in my panel loudspeaker with a full-rangeribbon driver, the autocorrelator noise-reduction system, thetracking down-converter subwoofer amplifier, and the SonicHologram. Last year I partnered with Bob Farinelli (formerpresident of Elan) to start a new company, Bob Carver LLC. Ournew designs are tube amps with the DC restorer and a floor-to-ceiling line-source speaker.

How much have preamplifiers andpower amplifiers improved over thepast decade, and why?What I'm going to say next will fly inthe face of much conventional wisdomregarding neutrality, nay, even thedesirability of absolute neutrality.

Today, a well designed solid-stateamplifier will be all but perfect from aperformance and listening perspective.It will have power to spare; it will havenearly a zero-ohm output impedanceand a bandwidth far beyond any rationalrequirement for perfect sound. Theprotection circuits will not color theoutput signal when playing speech ormusic into any rational loudspeaker, andthe maximum possible output current willbe far beyond the needs of any rationalmusic! This extreme performance will becalled upon only from time-to-time whenthe audio signal is extremely difficult.

The science of solid-state amplifiershas grown enormously over the lastseveral decades. Such an amplifier isexpensive though, because delivering thislevel of performance requires expensivecomponents—big heat sinks to keep itcool, huge power transformers to deliverthe current and voltage, as well as massiveenergy storage associated with the mainpower supply. I could go on and on, butyou get the picture, n'est-cepa?

Have the sounds of tubed and solid-state electronics converged towarda common neutrality in the past 20years? If so, what accounts for thistrend?Now for the fun! Tube amps! Over theyears many tube amps have become moreand more like solid-state amps in terms ofall the things mentioned above. This hasbeen done quite deliberately on the partof designers as the performance of theiramps has improved in many importantways to become as perfect as solid-stateamps. Against all odds, it was done withvacuum tubes, a far more difficult job thandoing it with transistors, and only a smallhandful of creative and talented designershave been able to pull it off. Otherdesigners have become so enthralled withthe unique and inviting sonic signature of

//////////////////////^^^^54 May/June 2012 tbsobsoloteBoond

vacuum-tube amps that they have taken a uniquely different pathfor great sound. This is evidenced by the many remarkable designsthat have very low output power, as well as individual frequencyresponses and distortion profiles that depend on each speakerthey're used with.

What began about ten years ago as an interest in the simpleintrinsic nature of tube amps has evolved into almost unbelievablypassionate work to extract the most possible realism usingvacuum-rube topology. We find that in order to evoke the absolutesound from our tube designs, we are forced to let go of long heldand cherished ideas about what an amplifier should do. We findthat we are no longer interested in facsimile reproduction; ratherwe find reproduction that sounds enchanting and real is far moreinteresting and serves our passions far better. In other words,we listen for something that could have been real somewherein time and space, even if in the moment it's not in our livingroom. Great tube amps, against all odds, can deliver music with amajesty and sweetness that is truly difficult to believe.

You choose to work today with tubed amplifiers. What arethe advantages you see to your chosen technology?I design amplifiers with tubes as well as transistors, and ineach case I have built my amplifiers so they present a musicalperformance that could have existed in another time and space.Since we are not there in that time and space, we can only inferthat it represents the real world, and the best we can know is that

the sound we hear is deeply satisfying and very moving. That'sthe secret.

Is Class D competitive with linear designs in sound quality,and if not, will it ever be?For over twenty five years I have waited for Class D amplifiersto come of age. Each year I read the many scientific papers onthe latest developments in switch-mode amps, and could nothelp but believe that just around the corner the promise of greatsound and cool efficient operation would come true. 1 built manyof them right here in my own laboratory with the thought theycould and would fulfill that final promise. I was never able tobuild a Class D amplifier that sounded as good as a linear one.There are several obscure, yet easily understood reasons for this,and just as soon as I find the time I plan to return to my latestswitch-mode design and try one last time before this year isfinished! I have not given up yet.

Has amplifier design reached its zenith where furtherimprovements are marginal, or will the next decade produceeven better-sounding preamplifiers and power amplifiers?Your last question is the most intriguing one for me; has ouramplifier science reached its zenith? Of course not. There isalways that next step; everything changes in science and audio,and the next amplifier design changes everything.

M2TECH FULL REVIEW BY STEVEN STONE IN THIS ISSUE!READ ALL ABOUT IT!

EVERYTHING SOUNDS BETTER WHEN YOU'RE YOUNG'M2TECH YOUNG DIGITAL TO ANALOG CONVERTER.. THAT IS.

AFFORDABLE PRICE -

Performance:- Decodes files as large as 384 kHz at 32 bits!- Asynchronous connection to PC or MAC using USB 2.0

Audiophile quality - Burr Brown DAC chips;768 kHz internal sampling rate

VERSATILE:- Accepts USB, Coaxial S/PDIF, TosLink or

AES/EBU balanced inputs- Seamless transition from one sample rate to another

To find a dealer near you, please go tohttp://m2techusa.biz/7page id=149

Distributed by

ESOTERICthEBbsolotBBOood May/June 2012 55

replace them, instead. IC's have evolved,but not in any revolutionary way, in myopinion, for the last 10 years.

Have the sounds of tubed and solid-state electronics converged towarda common neutrality in the past 20years? If so, what accounts for thistrend?1 think it is mostly improvements in thepower supplies and the capacitors usedfor both tube and solid-state productsthat make the difference, and maketubes and solid-state actually sound moresimilar.

You choose to work with solid-stateamplifiers. What are the advantagesyou see to your chosen technology?I choose to make solid-state analogcircuitry, exclusively. I design Class Aif possible; Class AB for a power ampoutput stage is most practical. I justpush the limits as much as 1 can withoutoverheating.

Some version of hybrid Class A and Class 0 looks like the future inoptimum audio design.

John Curl has been designing high-end audio electronics almostsince there was an American high-end. He earned a degree inPhysics with a minor in Electrical Engineering in 1966. Afterdesigning the sound-reinforcement system for the Grateful Dead inthe late 1960s, he worked as a design consulant to Mark LevinsonAudio Systems where he created, among other products, theseminal JC-2 preamplifier. He has spent the last 40 years as adesign consultant to a number of high-end companies includingParasound, Audible Illusions, and Constellation Audio. His VendettaResearch SCP-2 phonostage is considered one of the greatbreakthroughs in phono reproduction.

Is Class D competitive with lineardesigns in sound quality, and if not, willit ever be?Class D has improved considerablyover the last ten years. Some version ofhybrid Class A/D looks like the future inoptimum audio design. For me, I will stickmosdy to analog, but in future, we willrun out of quality audio parts and someversion of Class D will be necessary.

Has amplifier design reached itszenith where further improvementsare marginal, or will the next decadeproduce even better-soundingpreamplifiers and power amplifiers?No, amplifier design continues to beimproved on. When we ultimately go tohybrid Class A/D designs, we will haveboth relatively light weight, high power,low heat, high efficiency, and extremelyhigh-quality audio designs that will winlistening contests, much like sophisticatedturbocharged auto engines have replacedthe muscle car engines of the past.

How much have preamplifiers and power amplifiers improved over the pastdecade, and why?Preamplifiers and power amplifiers have only modestly improved in quality over thelast 10 years, at least the analog designs that I work with. The reason is the limitationof development of even more advanced active devices that can be utilized forsuperior audio products. In fact, most active devices normally used in audio havebeen discontinued, and poor quality or expensive equivalents have been introduced to

/ / / / / / / / / / / / / / /M^^

56 May/June 2012 thoobsoloteBOoni)

We are deeply convinced that the technically better amplifier-thisimplies also better measurements results-does sound better.

Cyrill Hammer was born 1965 in Switzerland and

earned Master of Science in Electrical Engineeringand Economics degrees at ETH Zurich. Before hejoined his family business (Spemot AG) in 2002

Cyrill was active in several management positions for SwissSMEs and as a business consultant with BCG, focusing onstrategic repositioning of major financial services institutionsand telcos. Within Spemot he manages and develops the newbusiness unit, Soulution.

How much have preamplifiers and power amplifiers improved over the pastdecade, and why?We have seen a tremendous improvement over the last ten years. New companieslike Soulution have introduced unconventional, innovative, and better approachesto resolve several technical issues of the amplification process that have never beenconsidered before.

Have the sounds of tubed and solid-state electronics converged toward a

common neutrality in the past 20years? If so, what accounts for thistrend?The understanding of how a high-endsystem should sound has considerablyevolved. New products which havepushed the envelope showed that thereis more to be expected from amplifiersthan the old stereotypes of solid-stateproducts being powerful but less musical,whereas tube amplifiers are claimed tobe more natural sounding but are lackingcontrol over the speakers. These productshave clearly shown that all relevant virtuesof the two approaches can be combinedin one product without compromising inany dimension of sound reproduction.Over time, customers will get used to thisnew quality of listening and will generallyexpect that from products participating inthe market. This automatically raises thebar in performance for all manufacturersand heavily fosters the convergence ofsolid-state and tube electronics.

You choose to work exclusively inClass AB solid-state. What are theadvantages you see to your chosentechnology?Taking into consideration all aspectsof amplification we are convinced thata properly done solid-state design issuperior to its tube-based counterpart.We are deeply convinced that thetechnically better amplifier—this impliesalso better measurements results—does sound better. However, goodmeasurement results, which are quite easyto achieve with solid-state amplifiers, donot in and of themselves automaticallyguarantee superior sonic results. Mostmeasurements performed today for theassessment of audio components aredone in the frequency domain. It is, ofcourse, most important to have perfectbehavior here, but it is only half the truth.Perfect performance in the time domainis no less important. This is especiallytrue of amplifiers based on negativefeedback. The theoretical concept ofnegative feedback is very powerful, andthe simplified mathematical equationsdescribing this concept do hold true. Butthey are only valid if the design addresses

///////////////////^^^^58 May/June 2012 thBSbeoluteBoond

the limitations of the concept. The time delay from input tooutput must be zero! Obviously in real life this is not possible.There are two ways to deal with this problem. 1 uther you just donot apply any negative feedback at all to your design (while givingup the advantages of the concept) or you do speed it up to thelevel (200MHz in the case of the Soulution 700 and 710) of a few-nanoseconds of time delay from input to output, where timingerrors are so small that they do not have any audible impact onthe sound. Once you decide to go the latter way a whole bunchof new challenges suddenly arise. Thermal conditions, stabilityof supply voltages, high-frequency designs, noise induction etc.,etc. With tubes as active components such designs would neverever be controllable and stable; they must be done with solid-statedevices. The result of such a project is a product that seems tobe ridiculously complex vis-a-vis the "simple" task of amplifying"slow" music signals. We at Soulution strongly believe that all ofthis is required to perform this task the best way possible.

Is Class D competitive with linear designs in sound quality,and if not, will it ever be?Several companies have already shown that it is possible to designClass D amplifiers with decent sound quality. However, if youwant to have your product performing at the cutting edge it isnot possible with today's known switching technologies. In orderto come close to the performance of the best linear design wewould need high-current semiconductors that provide switching

frequencies of several MHz or even GHz. Even if this kind ofsemiconductor could become available at some point, such adesign would still require a low-pass filter in the output with a cutoff frequency of about 0.5-lMHz and that also passes currentpeaks greater than 40 Amperes. Such a filter is not impossible todesign, but would be very demanding and expensive.

Has amplifier design reached its zenith where furtherimprovements are marginal, or will the next decade produceeven better-sounding preamplifiers and power amplifiers?The best preamplifiers available today offer residual noise anddistortion levels that are really minimal. We see some potentialto further reduce the noise floor resulting in better soundstaging,and also in reducing harmonic distortions. This will lead to evenmore natural and realistic sound quality.

The design of a power amplifier is much more demanding.There has been more margin for improvement here and therestill is. The Soulution Series 7 amplifiers were a real quantum leapwhen we introduced them in 2005.1 do not expect that anotherimprovement of the same magnitude will be possible; however,it could be quite substantial. We are currently working on severalareas involving the power supply of these amplifiers with quitepromising potential for improvement. Today we do not knowwhen this new technology can be introduced to the Series 7amplifiers. In any case there will be an upgrade path for existingproducts owners.

the absolute Boond May/June 2012 59

The sound of the very best tube and solid-state electronics isconverging. This is not surprising because among serious audiodesigners there is a common goal of reproducing a musical event.

Lew Johnson - Bachelor of Chemistry, University of

Minnesota 1968; Bachelor of Arts, University ofMinnesota 1968; Ph.D. Economics, University ofWashington 1972. Co-founder of conrad-johnson design,

inc. 1977. Musical instruments attempted: clarinet, banjo,electric bass; mastered: none. Active in the audio industry forover three decades, both in private capacity as co-designer, co-owner at conrad-johnson, and in leadership positions in industryassociations (AAHEA, CEA).

How much have preamplifiers and power amplifiers improved over the pastdecade, and why?At conrad-johnson, we have made significant progress in the past decade. Circuitrefinements have offered significant improvements. In preamplifiers, a newapproach to the basic circuit design has enabled us to build on the quantumchange in performance that we managed back in 1996 with our ART preamplifier.In amplifiers, ongoing improvements to the voltage-gain stages have resulted in

more evolutionary progress. Much ofthe improvement in the last decade isattributable to the proprietary Teflondieclectric capacitors that we helpeddevelop, which have found applicationin both our amplifiers and preamplifiers.Unfortunately, these capacitors arevery costly, limiting their applicationto higher-end products. We introducedthese capacitors in our top modelsstarting in 2003. We find that in recentyears, a few other manufacturers havealso begun to use similar capacitors.

Have the sounds of tubed and solid-state electronics converged towarda common neutrality in the past 20years? If so, what accounts for thistrend?The sound of the very best tube andsolid-state electronics is convergingbut with some ways to go yet Thisis not surprising as among seriousaudio designers there is a more or lesscommon goal of reproducing a musicalevent. There remains, however, somedifference in approach between thosewho, like ourselves, seek to honor themusical performance (trying to preservethe emotional element of the music) andthose who seek to replicate the "objective"details of the recording (tending to focuson minimizing distortion, maximizingbandwidth, etc.). Presumably the intentof the recording is to honor the musicalperformance, so ultimately these cometo same objective, though from asomewhat different angle. 1 think thisdifference in approach accounts as muchfor the differences in character amongelectronics as the technologies employed.

You choose to work primarily in tubedcircuits. What are the advantages yousee to your chosen technology?At conrad-johnson, we have worked inboth tube and solid-state circuits, thoughcertainly with tubes to a greater extent.Tube circuits offer several advantages.First, the size, heat dissipation, and costof the devices tend to dictate relativelysimple circuits, and our experience isthat simple circuits sound better. Second,tubes are inherentiy superior voltage-

//////////////////////^^^^60 May/June 2012 tbeBOBoloteeoond

amplifying devices. Typically a tube voltage amplifier with nofeedback is roughly an order of magnitude more linear than asolid-state device (the transfer function is about 1/10 as curved).This is simply because they operate comfortably at much highervoltages, making the output voltage a much smaller percentageof their range (a shorter segment of a curve is a better linearapproximation than a longer segment). To get around thisproblem, transistor circuits usually involve more elaboratecircuits (see first point above) with more devices and heavy-handed application of negative feedback which has its owndrawbacks. Finally, vacuum tubes produce predominantly even-order distortion, which is musically related to the original toneand thus unobtrusive. (FETs share this property with tubes, but,like bipolar transistors, are less linear than tubes.) That said, Ipersonally believe that the greatest strides in amplifier circuitswill be in hybrid circuits with solid-state devices employed todo what they do best (current gain). We have had already hadconsiderable success with such circuits.

Is Class D competitive with linear designs in sound guality,and if not, will it ever be?1 tend to think that Class D circuit design is an approachbest relegated to producing low-cost, physically manageablemultichannel amplifiers—where one might accept somecompromise in sound quality for the sake of scjueezing five, six,

or seven 100 watt channels into one moderate-sized package fora budget home-theater installation.

Has amplifier design reached its zenith where furtherimprovements are marginal, or will the next decade produceeven better-sounding preamplifiers and power amplifiers?On more than one occasion I have thought that we had reachedthe zenith of design and that further improvements would onlybe marginal in nature. In each case this period of malaise wassoon followed by truly exciting breakthrough developmentsresulting from new materials technology and new insights intocircuit design. There is ample historical precedent for this kindof self-deception. In the early 1900s, the Edison companyconducted live vs. recorded demonstrations of its new EdisonDiamond Disc recordings played back on spring-motor-drivenEdison acoustical phonographs. Listeners swore they couldnot distinguish the live performance from the recorded one,implying that any further improvements would be marginal. Wesee that position as laughable today, even though it recurred inthe 30s, and in the 60s, and with "perfect sound forever" in the80s. In reality, it is still the case that playback of a recordingrarely fools the careful listener into perceiving it as live. Thereis still plenty of room for improvement throughout the audiochain and no doubt we will continue to see that improvementin the coming decade.

The Best $8000 Preamp Costs Under $2700PrimaLuna's Flagship Preamplifier

"The DiaLogue Three has atremendous wow factor... it'sdifficult to believe that suchengaging, gorgeous sound,coupled with a wonderfullyexpansive soundstage, canbe had for such a relativelymodest price."

-Jim HannoThe Absolute Sound, Januar

The PrimaLunDiaLogue Three isa shoo-in"

-Art DudleyStereophile, August, 2011

WJ PrimaLuna*The DiaLogue Three

53 lbs of premium parts and point to point wiring. $2699909.931.0219 info@primaluna-usa.com primaluna-usa.com

the absolute Boond May/June 2012 61

The advantage of single-ended topology using triodes lies in the realpossibility of achieving the level of sound reproduction that closelyapproximates the actual sound of live instruments in space.

M M ladimir Lamm was born in the former Soviet Union and

V^ holds an M.S. in Electronics and Solid-State Physics.He was a professional table-tennis player; for manyyears played in a symphony orchestra; was involved in

the Russian Space Program; studied psychoacoustics in depth;developed a theory called Absolute Linearity of the System, onwhich his audio designs are based with predefined and predictableparameters (eliminating the need for a trial-and-error approach todesign). Founded Lamm Industries, Inc. in 1993.

How much have preamplifiers and power amplifiers improved over the pastdecade, and why?1 believe that I have dealt with this question to some extent in my answers to questions2 and 5. I would just like to note that in light of a very rapid growth marked bythe proliferation of increasingly affordable digital technologies, audio equipment hasbeen enriched with various features, the implementation of which would've beenquite problematic as recently as 15-20 years ago due to price and overall dimensions.

Have the sounds of tubed and solid-state electronics converged towarda common neutrality in the past 20years? If so, what accounts for thistrend?Partially. The improvements that havebeen made on this path are in generallyrelated to a couple of aspects: (1) agrowing understanding of the necessityto re-examine the role of feedback inthe audio path, with such awarenessitself already providing an opportunity toscratch at least the tip of the iceberg; and(2) a gradual realization by the engineeringcommunity that the interaction betweena man and a sound-reproducing systemtakes place on many levels—those thathave already been studied and supposedlyunderstood, as well as those that arelargely unknown and mostly hidden fromus for the time being.

You choose to work primarily in tubes,but you have produced single-endedtube and solid-state Class AB designs.What are the advantages you see toeach of these technologies?I am working with tube, solid-state, andhybrid technologies utilizing single-ended (Class A) and push-pull (Class Aand Class AB) topologies. However, mypersonal preference is for the single-ended topology that employs vacuumtriodes in the output stage. The advantagelies in the real possibility of achieving thelevel of sound reproduction that closelyapproximates the actual sound of liveinstruments in space.

Is Class D competitive with lineardesigns in sound quality, and if not, willit ever be?No, it is not. And I would like to respondto the second part of this cpestion withan allegoty. Any field of human activitydefines a number of requirements which,when properly implemented, guarantee apositive outcome. For example, the basicrequirement in the army and sports is anable-bodied individual. So, it would bequite natural to concentrate on searchingfor such an individual (especially as weknow where to find him). However, outof the blue we decide to choose a feeble-

///////////////////^^^^62 May/June 2012 the obsolete saund

bodied person who, on top of that, is encumbered by variousdiseases. Having made this decision (which is a priori improper)we start justifying it to ourselves and others by citing the greatstate of our medicine, which is capable of curing many ailments.

Of course, this allegory illustrates the utilization of ClassD topology in high-end audio only. There are many technicalapplications in which implementation of high-efficiency poweramplifiers is not just very desirable but sometimes the onlyreasonable solution.

Has amplifier design reached its zenithwhere further improvements are marginal,or will the next decade produce evenbetter-sounding preamplifiers and poweramplifiers?For the sake of brevity, I will once again usean allegory. We know the names of greatmasters—Amati, Guarneri, Stainer, Stradivari,etc.—who became universally known andrespected for their unparalleled creations ofbowed string instruments. These instrumentshave passed the test of time, which is generallya determining factor in evaluating the real worthof any object and/or idea. In this day and age,while possessing very impressive scientific andmathematical knowledge, along with access to

powerful technologies, we nonetheless can only approach diepreviously accomplished mastery level when producing the sametype of instruments.

Please note that whether we are talking about musicalinstruments or electronic audio equipment, we are dealing withdevices that interact with the human structure itself—in all itscomplexity. I think that if future research in the field of high-endaudio will take this—and all related factors—into consideration,and begins work in this vein, we can expect very interesting andserious results.

\

V_

0 V1 V1-*<

1

-'

_̂

- 1L L

Enjoy Solid State UUithout the Cdge.

/MM; <\l}i)K

The all new Tube/Class D hybrid amplifiers from Rogue AudioMedusa, 200 watts per channel, $3,995 • Hydra, 100 watts per channel, $2,995

Rogue Audio, Inc. • Brodheadsville, PA • 570-992-9901 • www.rogueaudio.comtbEBbsalotasoood May/June 2012 63

Simply put, solid-state (vs. tube) offers the designer finer controlof the musical signal. This is particularly valuable in music withcomplex waveforms such as classical.

30 years, there is much room forimprovement in implementation ofthese circuits. Interestingly, and this isa key point, improvements in specificationsdo not always equate to better sound.Therefore, not only do we measure,we listen. Individual parts selection isdone by thousands of iterative listeningtrials. Our process includes tirelessexamination of materials, includinglead length and gauge in every resistor,capacitor, transformer, and hookupwire. In the end, every single part insideour components is custom-made. Wehave nurtured our relationships withparts manufacturers to get exactly theproducts that we specify. Then thereis circuit topology. Best practices inshielding and micro-signal groundingare widely observed, but the designer'sexperience and intuition still play adominant role. Altogether, the fine-tuning process, even after the maincircuit and chassis designs are complete,takes us two to three years.

This extreme effort is devoid of theprimary concern that many "established"manufacturers must live by—keepingthe cost of the parts low. That's not aprimary consideration at BAlabo. Theresult is a component that offers anaudio experience unique to our brand,that cannot be copied or imitated, andcan be immediately appreciated by thediscerning audiophile.

I built my first amplifier in junior high school. Back then, it

was about my love of music, as it is today. After majoring inelectronic engineering, I worked at Nagaoka, a manufacturerof phono styli and head amplifiers. There I learned about

signal conveyance at extremely low levels. Eight years laterI went to Luxman and after another twenty years, becameLuxman's chief engineer. It was great preparation to startBAlabo where "Sky is the Limit" is our maxim.

How much have preamplifiers and power amplifiers improved over the pastdecade, and why?A great deal. Why? Because it was ten years ago we founded BAlabo! But seriously,you can observe that many of the companies at the extreme high end have beenfounded within the last decade. There is probably not a precise metric to quantify"how much" other than to say that improvements have been realized across the boardin resolution, musicality, usability, and aesthetics.

At BAlabo, we have endeavored to push our vision of what is possible in eachof these areas. Although analog circuit design has evolved very little in the past

Have the sounds of tubed and solid-state electronics converged towarda common neutrality in the past 20years? If so, what accounts for thistrend?Yes. I believe that the primary principlethat guides this convergence is thedesigner's prowess combined with hisability to judge good sound, whether tubeor solid-state. Personally, I'm not a fan ofeither the 300B or KT-88 tubes.

You choose to work primarily insolid-state Class AB. What are theadvantages you see to your chosentechnology?Simply put, solid-state (vs. tube) offersthe designer finer control of the musical

///////////////////////^^^^64 May/June 2012 thaabaoloteBoond

Signal. This is particularly valuable in music with complexwaveforms such as classical. Fven the best tube designs begin tohave difficulty with full-scale orchestral and symphonic music.This is most evident in power amplifiers, as most listenersknow, but during critical listening, even tubed preamplifierswill fall short of the best solid-state in control, structure, andindividuation of instruments in a large and complex soundfield.

We chose Class A transitioning to AB because it offers thebest of each technology. Class A improves low-level crossoverdistortion and Class AB offers vigorous sound quality withexplosive dynamics. Guided first and foremost by soundquality and after many listening trials we decided on the optimal"crossover" point for the handoff between Class A and AB.Interdependent variables include the size of the power supply,the amount of current used in the output stage, and the typeof output devices. These all react dynamically with one anotherand must be carefully designed in harmony and with ampleheadroom. The larger size and heat dissipation characteristicsof pure Class A designs were considered negative factors intargeting a 500Wpc amplifier.

Is Class D competitive with linear designs in sound guality,and if not, will it ever be?No. Class D can't really be considered for super-high-endperformance in its present stage of development, although it

can be fine for mid-market products. In the future Class D mayhave some promise if the carrier signal can be stripped awaywithout affecting the sound quality. This could mean largerand heavier devices in the output stage though—thus defeatingsome of the practical advantages of Class D.

Has amplifier design reached its zenith where furtherimprovements are marginal, or will the next decadeproduce even better-sounding preamplifiers and poweramplifiers?There is no limit to performance improvement in the analogworld. An engineer should always aggressively pursue bettersound and never consider a design to have reached its zenith.

There are still many conditions that are not readilymeasureable that affect the quality of sound. In the future, onething I would look toward is the ability to control the directionof spin of the electron. This level of control would help toeliminate some of the random variations we hear when similarparts sound different from one another.

On a related precursor, the recording industry should alsotake drastic measures to improve the signal conveyance chainthrough the mastering process in order to preserve the signalbetween source and consumer storage media. Once signalintegrity is lost, it can never be restored no matter how good theplayback devices.

tbEBbsalotEsoood May/June 2012 65

have assumed a popular role—warmingup the sound when mated to a solid-statepower amplifier. You could speculate thatthis results in a subjective neutrality in theears of the listener.

You choose to work primarily in solid-state/single-ended Class A. What arethe advantages you see to your chosentechnology?At some point in the past I lost interestin complex amplifiers, so now I enjoyextracting really good sound from simpleamplifiers. This naturally leads to solid-state Class A, where I can make a good-sounding low power amplifier with aslittle as a single FET and a light bulb.

And I do.

Is Class D competitive with lineardesigns in sound quality, and if not, willit ever be?Does a $10 bottle of wine compete witha $100 bottle? Of course it does, and itoften wins based on price. Right at themoment Class D designers seem to bestill focusing on the objectively measuredperformance of their amplifiers. I expectthat at some point the economics of themarketplace will encourage them to paymore attention to the subjective qualities,and then they will probably play a greaterrole in the high end.

Has amplifier design reached itszenith where further improvementsare marginal, or will the next decadeproduce even better-soundingpreamplifiers and power amplifiers?

I am optimistic. I think the poweramplifiers will be mine, and thepreamplifiers will be Wayne Colburn's.

The last ten years have once again demonstrated that high-endamplifiers with part-per-million distortion numbers and othersuperlative specifications are not very popular. It's like pure distilledwater-it has no character and most people don't want to drink it.

How much have preamplifiers and power amplifiers improved over the pastdecade, and why?The last ten years have once again demonstrated that high-end amplifiers with part-per-million distortion numbers and other superlative specifications are not verypopular. It's like pure distilled water—it has no character and most people don't wantto drink it.

If there has been progress, it has been where the subjective character has beenrefined in the service of the listener's experience. To paraphrase McLuhan,we are turning our mature technologies into art.

Have the sounds of tubed and solid-state electronics convergedtoward a common neutrality in the past 20 years?No, just the opposite. Anything resembling convergence to objectiveneutrality occurred in the late 60s and early 70s, and since then tubes and solid-state have diverged, catering to different needs and tastes. Tube preamplifiers

//////////////////M^^^66 May/June 2012 the absolute sound

'////////

When speaking about the top high-end companies, you can sayglobally that tubed electronics are more neutral and solid-stateelectronics are more coherent and less sterile than twenty years ago.

Jiirgen Reis has always played and listened to music. At

University, he studied Electro-Acoustics and ElectricalEngineering. Jiirgen became Chief Engineer at MBL in1984 when he invented the carbon-fiber radial tweeter.

Since then, Jiirgen has been responsible for the technigueand sound of all MBL products. 2012 marks his 30th MBLanniversary. Jiirgen doubles as a recording engineer (in thestudio he built), shreds on electric guitar, sings in a chorus,and cycles.

How much have preamplifiers and power amplifiers improved over the pastdecade, and why?Wow. Broad question. Volumes have been written about this. Simply put, I think this isa secondary benefit of the great improvements in loudspeakers and some recordings,and these two facts have given engineers better tools to improve the quality ofpreamplifiers and power amplifiers.

The very, very small parts make a huge difference, especially in the preamp—forexample, a resistor with brass, copper, or steel "holders." Today you can hear large

differences between small parts and theirconstruction materials that were not soeasily apparent ten or twenty years ago.

Have the sounds of tubed and solid-state electronics converged towarda common neutrality in the past 20years? If so, what accounts for thistrend?Yes they have. When speaking about thetop high-end companies, you can sayglobally that tubed electronics are moreneutral and solid-state electronics aremore coherent and less sterile than twentyyears ago. The differences between themare shrinking.

Why? Designers have much moreexperience now than ever before, andboth sides are listening to the other'selectronics—tube guys listen to solid-state and vice versa.

You choose to work primarily insolid-state Class AB. What are theadvantages you see to your chosentechnology?Bigger question! I work in lots oftechniques, A, AB, now Class D, as well.I have two main reasons why I don't liketo work with tubes. MBL products aredesigned so that our customers havea long enjoyable time with their gear,and changes come slowly and carefully.Tubes are constantly aging and changingover time, and the differences betweenseveral tube manufacturers and factoriesare large—even today—so any time theychange the manufacturing spec, tooling,material, etc. the behavior and sound willchange and I would have to completelychange my design to accommodate thechange in the tube to maintain the soundI want the customer to enjoy.

Also, with tube designs you mostlyhave transformers at the output and oftenat the input. Transformers have a hugeinfluence on the sound quality. Qualitycontrol of transformers is very difficultto maintain, so that next year you get thesame iron and copper on the windingsas you did this year or last year. It'smuch more difficult to have a tube ampsounding the same this year and last year,if you are planning for a constant sound.

///////////////////^^^^68 May/June 2012 the obsolete Bouod

* *

With SOiid-SMe, the circuits arcmore rcpeatable. You can bettercontrol the quality, so next year'sproducis will sound very similarto or the same as last year's. This ~stability is the main reason I choosesolid-state.

Between classes, you mustunderstand the principal differences. Roughly, ifyou can comprehend what causes the main differences, you canbuild a "hybrid" of Class A and Class AB. MBL preamps runClass A up to 7 volts, and in our Reference power amps the signalquality is determined by Class A, and is sort of "swimming" ona Class AB power supply. I prefer the sound of Class A, butyou can design Class AB circuits that sound similar at high andlow levels. With solid-state vs. tubes, you have different circuitryfor the plus and minus, and this always sounds different whenvou change the polarity of the sinewave. With Class A, youdon't have the differences between positive and negative voltageswings. With PNP and NPN transistors you always face theproblem of dealing with different times of charge and discharge;in one direction you always have too much current, the other, notenough. With Class A, you eliminate this crossover.

Is Class D competitive with linear designs in sound quality,and if not, will it ever be?

I have worked a lot lately with ClassD. Ninety-nine percent of Class Dcircuits are not competitive withlinear circuits. There are someexceptions and, of course, I like

to think the new MBL Corona Lineis one of them. At CES this year, I

heard a few other Class D designs thatI thought sounded good. In three years,

we might have five-percent sounding okay andninety-five percent sounding poor. Look at solid-state thirtyor forty years ago—it sounded awful compared to tubes.We had no idea why the tubes sounded more "pleasant" tothe ear in some areas, even though they had 100 times thedistortion. It took many years to understand. Only companiesthat deal with both sides can develop an understanding. MostClass D sounds sterile. It's tricky to figure out what to do tocompensate for that.

Has amplifier design reached its zenith where furtherimprovements are marginal, or will the next decade produceeven better-sounding preamplifiers and power amplifiers?The next decade will produce better-sounding preamps andpower amps, but perhaps not as large-scale different as in pastdecades. I am always working on something better, more natural,more human, more coherent, more lifelike.

theabsalutBsound May/June 2012 69

Strict adherence to a class designation for an audio designer is likeasking a painter to reduce the number of colors on his palette. The endresult may be less vivid than you had hoped for.

HI ow does this work?" Asking this question, at age12, led to my lifelong devotion to uncovering themysteries of electronic design. My backgroundincludes working as an engineering assistant with

Ampex Corp. and studying electronic engineering at the DeVryInstitute. I formed Rowland Research in 1981 which became JeffRowland Design Group in 1987. Since then, I have developedmore than 35 critically acclaimed audio components that arenow enjoyed by countless listeners around the globe.

How much have preamplifiers and power amplifiers improved over the pastdecade, and why?First, let me thank The Absolute Sound for including me on this august list of designers.I consider it both an honor and a privilege.

I've been an audio designer for 40 years and never in that time have I felt a greatersense of promise for the future of high-end audio. Recently; it's been my pleasureto hear a number of sound systems I believe are approaching true greatness inaudio reproduction. The possibility that audio components ma)* soon capture all theemotional power of live music is a dream never closer to being realized.

Our reference system at Jeff RowlandDesign Group is revealing to such adegree that it seems eerily capable oftransporting the listener to the musicalevent itself. Understand, our referencesystem is a collaborative work, featuringcomponents and design ideas from awide range of audio engineers. With ourcontinued collective devotion to musicalfidelity over time, I see no limit to thecompelling listening experiences yet to beenjoyed.

There are many purely technicalreasons audio designs are improving. Forexample, my company's current designsbenefit greatly from electronic partsunavailable until quite recently. However,it is also true that designers themselves, inthis relatively young industry, have grownmore mature and capable.

New components, technologies,and design concepts are just piecesof a greater puzzle. It takes years tounderstand the complex relationshipbetween component parts and the endproduct. Audio design is an art form thatrequires a lifetime to master. There are noshortcuts.

Have the sounds of tubed and solid-state electronics converged towarda common neutrality in the past 20years?I believe there is a trend toward thecreation of a more natural representationof the original performance. This seemsto represent the overarching aim of allaudio designers, whether working withtubes or solid-state. We are all trying toclimb the same mountain. Our paths maybe different, but 1 believe we certainlyrespect one another's efforts.

You choose to work primarily in solid-state Class AB and in Class D. Whatare the advantages you see to yourchosen technologies?Over my career I have designed using awide variety of technologies. I prefer tobelieve that my work displays a willingnessto explore audio design regardless ofclass designation. While my basic designgoals seem best suited to the solid-statedomain, I am not overly concerned about

//////////////////////^^^^70 May/June 2012 theebBolutBsound

which class of technological platformI work within. You might say I am aproponent of the classless society ofaudio design, taking the best that each hasto offer in an attempt to create the finestcomponents possible.

Is Class D competitive with lineardesigns in sound quality, and if not, willit ever be?I consider Class D to be highlycompetitive in the present, and to offeran evolutionary pathway of audiodesign that may produce even moreastonishing results in the future. Again,it is not a matter of class distinction.The application of technology is what isimportant. It can produce brilliant or poorresults depending on its implementation.Strict adherence to a class designation foran audio designer is like asking a painterto reduce the number of colors on hispalette. The end result may be less vivid than you had hoped for.

Has amplifier design reached its zenith where furtherimprovements are marginal, or will the next decade produce

even better-sounding preamplifiersand power amplifiers?Although high-end audio is a relativelyyoung industry, many high-end productsfrom mature companies have achievedour longtime shared objectives. Thesecurrent products are beautiful andreliable, and offer exceptionally highperformance and pride of ownership.

Flowever, I'm confident that nuichremains to be discovered. Engineering isa discipline that seems to move in fits andstarts. There are slow periods followedby incredible breakthroughs. Science andart have always been restless bedfellows,but when they come together it can bebreathtaking and worth the wait. We cannever truly appreciate the next level of artand design until we actually arrive.

The passion for discovery is a silent butpowerful motivator for both science andart. The art of engineering is especially

exciting as we have the opportunity to daily manifest abstractideas into reality. Through our passion for our work we can hopeto inspire the next generation of designers and listeners on theirown journeys to musical revelation.

theebBolutesound May/June 2012 71