Friday, October 28, 2016

Wizard on the Hill

John Iverson was the greatest story teller of all, but I've got my little story to tell about him.

A very geeky friend of mine was building DIY transistor amps in the early 1970's, I think he had his first one in 1973, while we were still in high school.  This was cutting edge stuff at the time.  His first was modeled after the least powerful SAE amplifier, designed by James Bongiorno.  He bragged about the leading design principles.  Bongiorno did become well known soon as one of the top audio designers.

By 1975 or so that friend was actually working for James Bongiorno, in the original G.A.S. factory in Van Nuys, CA, middle of the San Fernando Valley.  I was no longer living in The Valley, but had come by from Pomona College near San Bernardino.  My friend introduced me to James at that factory, who was busy wrapping up some piece of work.  The great James made some joke, I think he had already thought of the name Charlie the Tuner.

James: "How do you like your Tuner, Charlie?"

Me: "What?"

Friend: "Oh he's making a new tuner, called Charlie.  It's some kind of joke."

Me: "Oh, sounds cool.  I like good tuners.  I liked those ones with scopes.  But also that have good sensitivity."

Almost three decades later James would be arguing at me about tuners on the FMTuners group.

Anyways, that same friend left G.A.S. and lived with me during his first year at Cal Poly (and my second-to-last year at Pomona College).  And by that time he didn't think James was necessarily the very smartest designer, though he had done some good things.  The very smartest designer was John Iverson.  And that was not only his view before long.  Iverson quickly became famous for the A-75 amplifier, and rumors of the unique massless Force Field speaker which some people got to see.  Then, later, well known for the EK-1 strain gauge phono system, which got rave reviews but was not easily found or purchased.


During my high school and college years when I was living in Los Angeles I sometimes dropped into Mel Schilling's Music and Sound store, which was just on the side of my neighborhood in Woodland Hills.  Little did I know Mel was or would be a parnter with Iverson (he certainly was by the last time I visted M&S in their larger store further down on Ventura Blvd).  It seemed to me all the interesting people and things were on the East Coast.  That's where I thought Marantz was (though they had moved to the Valley before I entered High School...and before I finished High School had moved to Chatsworth, just a few miles from where I lived).

So while I thought all hi fi production and cool people were on the East Coast, such as Marantz (I believed them to be in Long Island City or Woodside New York) in actuality, they had started moving to my home city of Los Angeles while I was till in elementary school.  While I was in college they opened one of the largest manufacturing buildings ever in Chatsworth California, not far from my childhood home of Woodland Hills.  Also in Chatsworth later were G.A.S. and Iverson's Electro Research (I had no clue where that was, once again I figured far away).

Iverson was the mythical wizard, my friend spoke of (sometime later telling me about the truly magical force field speakers, sometime later after they had already been dismantled, but I was scared to go near them anyway), and before long I was reading brochures about things like the amazing EK-1 and A75, they looked and read so cool, and reading praise of these things by J Peter Montcrieff in the International Audio Review.  Mentions may also have early occured in Stereophile if not The Absolute Sound.  Most of these review rags had said barely anything about Bongiorno, for example, who himself often claimed he virtually invented the modern transistor amplifier complimentary ("symmetry") circuit.  (BTW, a friend of mine and I and other seem to be thinking quasi complementary is still better anyway, for various reasons, even transistors today decades later aren't really complementary enough.)  But Iverson seemed to get lots of buzz.  But perhaps it was all because I visited Music and Sound and Mel Schilling was Iverson's partner.  I had no clue about any connection between Mel Shilling and Iverson.  I though Iverson lived on the east coast, where all good hi fi came from, I thought then.

Anyways, despite living near the Wizard for years, and haunting a few of his haunts, knowing some people he knew, I never met the Wizard while I lived in LA in the 1970's.

I met him in the beginning of the years of his decline, we all know now, his desperate national tour after after giving up the big factory on Empire Blvd. in Lake Havasu (the desperate tour did pan out fairly well, actually, and his boat was beginning to rise again before his biggest fall a couple years later).  All seemed fine to me (not paying close enough attention).  Iverson had come to speak at a meeting of the San Diego Audio Society, of which I had been "President" for a decade.  (I didn't actually do much more than print and mail the meeting announcement, after being told by a friend that Stereo Unlimited had scheduled a speaker.  No, we didn't use email or the internet in the 1980's.  I never had to round up speakers...they just appeared largely through the efforts of Bruce at Stereo Ulimited, or a friend of mine,...and they included many of the greats.)

It was one of the most memorable meetings.  I was almost...almost sold on getting an Eagle 2A right on the spot.  I can't remember what discouraged me.  Perhaps I thought an Eagle 7A would be even better.  I couldn't make up my mind because I felt I didn't need the power of the 7A but I would have loved the higher bias.  Of course I also liked the lower price of the Eagle 2, and people seemed to praise it more.  Anyways, I didn't buy anything, but I found Iverson to be the most charming speaker, and especially when he invited everyone in the end to an after-meeting dinner.  That may have been the only time that ever happened.  And it was the most fun part of all, while Iverson continued to tell one far out story after another, of which I sadly can't remember anything.

I liked Iverson a lot, I thought.  He wasn't the scold I had imagined (Bongiorno, for example, I would describe as prickly, for as much as I respected Bongiorno I could hardly avoid setting him into a rage of some kind by showing the tiniest questioning of his authority), instead Iverson was just a really cool guy you could say anything to and he'd have a great answer.  And that's probably part of why my friend thought he was the smartest also. But despite both my friends (my high school era friend and the one at the audio meeting in 1988) being Jewish, neither mentioned any trace of anti-Semitism.   Only now in 2016 I read about Iverson and hear him described as flaming bigot, anti-semite, and so on.  I never saw that myself, though I did hear the some of the libertarian right wing anarchist side in 1988 (it seemed to me then he wasn't nearly as far out as many), and it may have been that part which was central to his undoing (as one who strongly avoided paying taxes, for example, leading to increasing avoidance of and encroachment by authorities, I think that he would not contact the police when perhaps he actually needed police protection, as might well have been necessary in his final predicament).

Another friend of mine who was actually at this 1988 meeting wasn't so impressed.  He pointed out that he was apparently living in a motorhome with his wife and business manager and selling product out the back door, and consumed two bottles of whiskey during the meeting and dinner, and was clearly lying about a number of things and worst of all didn't understand my friend's own wisdom.

Following Iverson's stories, one might have imagined Iverson on top of the world, with his own private jet and so on.  I figured that was exaggeration, but I never imagined him on hard times.

Anyway, I'll concede to the frequent consensus he was a technical genius, sadly never one who reached his potential, and a life-work sadly ended at least partly due to a dark side of himself, and the cruel world itself, but I also think of him as a kind of maniac, who toiled with an extreme manic intensity to produce highly polished and perfected designs.  He was a child prodigy at transistor circuit design, and could get complex arrangements working just right.  I think he highly polished the designs he came up with, but not to say he found the best possible designs necessarily, it seems there is always an even better design because the design space keeps expanding.  But he did some things right that others have had a hard time duplicating, and it seems nobody has really duplicated or bettered the Iverson thing in an Audio poweramp.  It was a special and so far unique magic, that required a particularly manic design and construction, and required a somewhat maniacal designer.

Comparing his 7A to Ampzilla I realize that the use of servo loops, for example, isn't entirely optimal, though I consider it far better than the usual capacitor coupling (or worse, transformer coupling).

While servo loops isolate the capacitor a lot, it's still sloshing around and messing with the low and other frequencies, and it's no way to get to a "null" of amplifier vs source, for example, which I suspect Iverson was interested in, as many were up until the 90's.  Much better simply to have correctly and thermally balanced push pull, which Iverson always achieved by design, careful matching, hand assembly, and fine tuning.  Of course the best of all is intelligent designs, and some believe the most intelligent design makes adjustment unnecessary,  but I think there is usually a performance price to be paid for that, and if your goal is to reach the very best performance--a true null not just an approximation--you cannot rely on slowly approximating solutions.  Then if something needs to be right on, to reach the very peak, this may require adjustment.  (Now it seems recent designers like Nelson Pass have created circuits that are inherently balanced and don't need any adjustments.  I think that's part the progress of cleverness--in particuar Nelson has been very clever, and part the giving up on the pursuit of the nth degree of nulling, and part the luxury of huge available chassis dissipation made possible by ten to eighty times pricing, most often for far less available power.  Even with amplifiers weighing 10 times more Nelson claimed (until the recent .5 upgrade, followed by even better .8 upgrade) not to be interested in creating "arc welding amps."  So you might not be able to arc weld with a 300 pound amplifier, but the 30 pound amplifier from Iverson will arc weld all you want, and still not sound "transistory" with a smooth and wide open top and a warm middle.  A classic "transistory" Class AB hard, steely, cold, clinical soudning amplifier would never become the choice of J Gordon Holt ever.  So you get both the arc welding, and the refined sound, in the original $895 30 pound amp from Iverson.  In 1985.  A miracle!

I further speculate that Iverson may have been reaching for a particular possible design that gets you to null rather than just "good."  And that would be the upper end of the Baxandall optimal feedback.

Baxandall determined in 1960 that negative feedback doesn't actually reduce distortion overall unless applied in the correct amount.  Incorrect feedback actually increases distortion, though it often pushes distortion up to higher and higher harmonics, for example, so sometimes with limited bandwidth measurement miss this.

The correct feedback for the simplest transistor amplifier is either 4 db or less or very high, 30dB IIRC.  Most transistor amps err with feedback somewhere in between.  Some of the better ones use simple circuits and low feedback, but not necessarily low enough.  The 4 db would apply to a single transistor, with multiple transistors the optimal feedback would be even lower.  And on the high end, a more complicated amp might need even more feedback--if it could be applied.

Now you can go after the high end of optimal feedback.  But it's very hard because the open loop amplifier has to be very linear and very stable to handle such a high feedback level.  It takes very careful, even maniacal design.  And that's how I consider Iverson a kind of maniac over these details.  And stiff, probably regulated power supplies also.  And finally he obsessed over reducing propagation delay closer and closer to zero, which seems unnecessary to me, but certainly important in feedback amplifiers, and for achieving simple good nulling results.

The one thing I am sure about is that he obsessed over his design details.  And that's partly why his amplifiers are so widely regarded as best, to those who have spent some time with them.

A few other notable amplifiers are based on the high feedback method, including Halcro and Wolcott, very very expensive.  Even those wouldn't replace an Eagle 2 for many, since the Halcro lacked the low impedance drive (really doubling down to 2 ohms, and playing at even less) and the Wolcott was actually a tube amplifier, also certainly not a low impedance champ.

Iverson was creating his super high technical performance well regarded high end amplifiers, hand built in the USA, for peanuts, in the 1980's.  Earlier products under the Electro Research brand (originally started by Iverson and Schilling) were mind blowing expensive in their day, though by todays's standard extreme bargains as the high end icons they were and still are.

The Iverson Eagle 2 was highly praised in Stereophile mentions.  It was said to be much better sounding than nearly all transistor amplifiers, with excellent midrange, highs, and bass.  It had much cleaner and more enjoyable upper 3 octaves than the Eagle 7A.  It was the personal reference amplifier of the founder of Stereophile himself, the very respectable J Gordon Holt (curiously having the same middle name as Iverson)--a person who could have the best of transistors tubes or anything.

Enough!  I have finally bought an Eagle 2 this week, and will see how it compares.  If I like it, I will have it upgraded by Russel Sherwood.  My hope is that it doesn't have the usual Class AB transistor amplifier sound (though I've seen many offhand statements to that affect, always by non-owners, owners always describe it as far better than other transistor amps in midrange presence and high frequency smoothness).

One way or the other the wizard was lost, not long after I finally met him.  But the legend, and hopefully the amplifiers, live on.  (BTW, I wonder about the intended buyer for Iverson's special gun. If such a buyer was intending the gun for criminal activities anyway, why not one more?)

Class AB I believe has an inherent "bright" or "thin" sound once you get past the Class A portion.  Feedback, especially the low baxandall optimal feedback, can't entirely eliminate this.  But high feedback can, at least if you clean up the notch itself, and use reasonably high AB+ biasing, Class AB  with high feedback can duplicate Class A sound I believe.  But few designers push the feedback high enough.  I speculate that Iverson did, he pushed the open loop gain and feedback higher than anyone, and this gives his amp a peculiarly good sound.  He's not getting stuck in the middle feedback morass.

The Eagles also run pretty high bias.  The 7A has considerably more bias, but the 2A is better anyway I gather, and is simpler and more effective being non-bridged.  In fact I remember Iverson and company steering me to the Eagle 2, Iverson spent all his time demonstrating the 2, and then seemed to think that was the best for me.  I wanted a low power amp in the Eagle 7 case running higher bias, stubbornly, couldn't decide.

You can achieve very nice low distortion with low feedback with Class A, or at least Class AB+ in most cases, most of the time.

Here's interesting info on the EK-1.  I regret not snapping one up when I had the chance.  A friend wanted info on adjusting "phase compensator" controls.  According to this thread the Singapore factory did so with a square wave test record, according to one owner, who did the same and was happy with his.  This does not guarantee that this method was approved by Iverson.

What Iverson has designed in the EK-1 is clearly a pair of discrete op amps, with associated circuitry, to implement a strain gauge preamp.  Nothing all that magic, the question is how good are his discrete op amps?  One number I hear claimed was better than 125dB S/N with inputs shorted.

That's pretty good, and that was actually just a guestimate anyway, and I've heard the opposite claim that EK-1's are noisy, and that might be true in some circumstances.  It appears that the designers use of  a solid stainless case is not coincidental.  With the kind of power Iverson is running in those op amps, one might expect high RF succeptibility.  The stainless steel probably works in most cases, anyway, that's one explanation for claimed variability.  Another is states of misuse and disrepair.  And, of course there is always: people make stuff up.  So what to believe?  I'm pretty open to believing it works well for some, not so well for others.

Anyway, nowadays one wouldn't do this sort of thing.  One would simply use the best available chip op amp, which is still the OPA 211, which has a hybrid silicon germanium process.  It can't be beat with silicon transistors in terms of low noise, distortion, etc.  And then an ordinary machined aluminum case would do, and if executed well, it would work for anyone.

And one would apply the best available EQ, well understood, the reverse of the RIAA, flat from 500 Hz down and flat from 2122 Hz up.  Fine tuned to each cart, that's what Iverson did and it's still good.

So many shortchange things, like saying you don't need EQ with strain gauge cartridges, and get away with none, or a highly uncompensated response, bass heavy and all.

It becomes so common, it takes unusual strength of character to stand out sometimes and do things the right way.  Iverson had a lot more moxie to do things to the nth degree than most at the time.

I liked Iverson so much...he had that charisma that some people do...I wanted to join his circus kind of feeling...I could so easily get an Eagle 2 to replace my stupid frying-sound Citation II.

I remember the moment of feeling like Iverson and Munro were family, after having talked about the two Eagle amplifiers and which would be better for me.  Having easily given up on the very kindly sale due to my indecision, Munro asks if I'm bothered by Iverson after he walks out.  No, I say.  I feel afraid for him.  "Tell that to John," she says huskily, smiling, turning away with a cough.

But the feeling to buy an Eagle amplifier, which few Americans realized they had the chance to, passed.  I think shortly thereafter a friend pointed me to the same of an Amiga 2000 computer with all accessories.  I jumped on it, which led to endless friends and clubs still going on, through my "exotic computers" club.  So with all that going on, I forgot about the Iverson amplifier, and when I had money again to consider buying somthing, I didn't much believe in amplifier differences, and besides the HCA-1000A got good reviews, seemed to be designed well by John Curl, so I got one of those.

Now I wonder if it isn't at least fool around with the hypothetical idea that amplifiers do sound different, and what special magic Iverson achieved, which I even vaguely remember to this day.  The HCA-1000A is still good, the HCA-1500A better, but I think I like the Krell FPB 300 still better, what else is there?


I also specifically remember feeling a bit worried about Iverson hearing him describe some of his exploits and anti-government feelings and the Audio Society meeting and afterwards.  I remember being very worried that this wasn't going to end well for him primarily, though sometimes he made me fear from the government also, that didn't worry me as much.  At this point I find it very hard to believe that Iverson lived much beyond the disappearance.  I think he desperately wanted to make a likely illegal sale in order to raise funds to free himself from debt, or to make a new expansion, in one way or another most likely to save his company and his career, just like DeLorean famously tried.  But Iverson's buyer was too unsavory, and prepared to just ambush him and rub him out.  The buyer wanted the gun for personal a doomday style weapon at their own residence or venue, where they could let loose and kill lots of people, but not worry about all the lead in the next days.  Almost certainly a mobster type, American or not.  I think the real military could find someone else to make the gun if they wanted it.  Mobsters have to go with what they can find and trust.  And really really don't want anyone else to know or be able to buy or duplicate it.  Iverson was good, but his unique genius at such things has been often oversold, I believe.  He was just willing to go farther out on his own for audio amplifiers than most others.  And a few other things.

Iverson was a shining light, I don't think he could hide for so many years.  And I don't think he really was the James Bond he portrayed himself as.  He was son of a reclusive but curious TV repairman in LA, and a great story teller, and a brave man but possibly too brave in one instance.

*A friend speculates that Bongiorno and Iverson simply copied circuits from the semiconductor manuals.  That is precisely what Nelson Pass said was his training, at ESS he read the semiconductor book and thought about all the circuits they showed, something for every occasion.  Nowadays the deepest design is still done by semiconductor designers, the ones who design integrated circuits.  But this is indeed a brand new world of powerful design tools and so on.  Not a world of wiggling leads.  Iverson was the man for and of his time of discrete circuitry, for doing his kind of thing, making miracles.  As always it wasn't individual circuits but a particular combination of them set just right which made Iverson's amplifiers great, and most ultimately in the Eagle 2 series because it wasn't an overreach but the simplest Iverson.  Likewise Bongiorno, there may well have been some cleverness in his combinations, but I do find his audio work prior to the 21st century to be not quite as good.  (I suspect he did far better in his post-millenial products than before.  The original Ampzilla and others were clear and dynamic amplifiers but lacking the smoothness and midrange transparency of Iverson's amplifiers, starting from the jaw dropping A-75 if not before.  It was no random thing that Mel Shilling co-founded Electro Research with him...he was clearly the best.

Iverson was the golden boy, and widely recognized as such at the time, and he probably could have had the world if things had worked out better.

I remember the praise J Peter Montcrieff of The International Audio Review heaped on the Robertson 4010.  They invented a whole new kind of power, and found that the 4010, a relatively low powered amplifier, had 1,000 (or perhaps 10,000) watts of Moxie Power.  In contrast, some other 300W amplifier was found to only have 3W of Moxie Power.  This is related to the increase or decrease of power into lower impedances, I believe.

The Robertson audio products were made by the Singaporean firm named Robertson that had been signed up to build the EK-1.  At some point, Iverson and Shilling bailed, selling the firm to the Singaporeans.  (The TAS story lays much blame on Iverson's absolute insistence on a cast Stainless Steel chassis, and not being satisfied with the castings.  This dragged out the introduction of the product for a long spell and jacked up the cost.)

It is not clear to this day whether the Robertson 4010 was actually designed by Iverson and obtained legally in the sale of the company, ripped off from Iverson by Robertson (as some have suggested), or a similar amplifier created using only the ideas of Iverson, whatever they actually were, as told to or figured out by the Singaporeans in the course of their interactions with Iverson.  In one way or the other the 4010 is an Iverson-like amplifier, the Moxie Power being found in all the others, probably better in the real, fully credited Iverson amplifiers.  The Eagle amplifiers were made under Iverson's supervision in one of his USA factories, the largest and most famous one being the 10,000 sq foot facility at Empire Drive, the final one being just a small building near his house.

(I called Iverson the Wizard on the Hill because in the Lake Havasu subdivision where he lived, which wasn't necessarily over opulent, he nevertheless had a somewhat unusual lot that had a small hill that the house was perched atop.  Such goodness for an audio guy.  I have the similar fortune of having a large setback to my house, and no nearby house having facing windows.  This makes for being able to be playing music at reasonable levels without anyone nearby even noticing.  A hill would be even better, and Iverson would have needed that.  Back in The Valley days he may have lived on a hill as I did and as did many people.  And then also, it just sounded good.)


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  2. Hello,

    Thanks for this article. I’m in Burbank and recently purchased an Eagle 2. What a fun amplifier!!! I also have a Robertson’s Audio 6010 on the way.

    Would you happen to know where I might find schematics for the Robertson and Eagle amps?

    Let me know if you are ever in Burbank!