The Wolfbox Story

Hello, my name is Ed Wolfrum and I am the inventor of the “Wolfbox”.

Recently I've received numerous e-mails and calls regarding my design of the "Wolfbox" and my association with Acme Audio. Let me set the record straight and present a first person account of the situation, since I am directly involved.

My relationship with Acme started in 2010 with the "Wolfbox" and terminated last year in 2013. I was never an employee of Acme, originally providing only technical consultation. But with discussions of resurrecting the original "Wolfbox" design for production, I became interested and hoped that it would be a productive relationship. As it developed, I became aware of the great marketing skills that Al Sutton and his team had with the Opticom limiter (which both Tim Mead and I engineered the new balanced front end and the gain reduction metering circuit of the new version).

Besides recreating the "Wolfbox" at Acme, we also worked on other early & improved versions of my designs, including two microphone pre-amplifier circuits (which we tested and breadboarded), "The United EQ" (a multi-band EQ I designed in the 70s on my own and which I built 3 prototypes with Jimmy Siracuse at United Sound, which Al then prototyped again and ultimately I never approved because of concept disagreements) and an early phantom powered "Wolfbox" (which I designed in 2008 having un-successfully found quality transformers of performance equal to or better than the earlier "Wolfbox" design). Other than the original "Wolfbox", all other designs as mentioned above were not marketed thorough Acme (though I was hoping to do so at that time) and thus remain proprietary to me and are protected.

All this was done on my trust in the integrity of Al. My only compensation from Acme Audio to this date has been our agreed 50% of the after cost profit of the first 25 (SN00-024) "Wolfboxes" which I built the majority of and supervised the building of a small number by Al and Heather, all 25 of whose performance I would later confirm and document before release. Other than the cleanup of cases and mounting of parts, I had nothing to do with the subsequent 25 so-called "Wolfbox" DIs (after the first 25).

Why I am no longer involved with Acme & Al has much to do with philosophy, integrity, & business ethics today, and the recording business (if you want to call it that???) as it is.

This requires some history.

As many of you have become aware, I have been credited with the invention of the so-called Direct Box. Whether this is accurate or not is up for debate, but I indeed designed (in late 1958-59), built and sold a plethora of them (using Triad A-11/12J transformers) in the Detroit area throughout broadcasting and audio recording studio facilities starting in the early 1960s through the 70s. By the middle 1970s almost every Detroit studio and radio and TV station (along with Bob Fine's studio in New York and a few others out-of-state) had at least one. I also built a special unit personally signed for James Jamerson, Sr. which his son (Jr.) now believes was stolen in the bass case with the "Funk Machine." I readily shared the information on how to build them with other Detroit engineers. So essentially my design was known long ago. Back then, the studios of note had the technical ability to design, build or modify gear for their own applications. Much of the audio technology we take for granted today was invented at studios like United Sound Systems, Detroit, Bob Fine in New York, Universal, Golden World and Motown. I assumed since it was so simple most likely others were doing it as well. Being in my teens I certainly did not have the financial resources to protect or patent it. Later, thanks to the research of others, I was told that I was the first. Big deal...I'm still far from wealthy, so perhaps that is how God wants it.

The first sale in the recording business was made to Jack Brown (RIP) at Fortune Records and he suggested I sell it to others. By the 1970s the market was saturated, but still it helped pay for college. Because of the relative unavailability of the Triad A-11/12J transformers in affordable small quantities, my responsibilities at United Sound and simultaneously running my own Audio Graphic Services, I ceased building them (other than for a few close friends when I could obtain Triad transformers).

In 2009 Dennis Coffee was interviewed by the BBC at the Motown studios and described the earlier "Wolfie Boxes". (The name was coined by the Eddie Willis, one of the Funk Brothers, and "Wolfbox" which James Jamerson Jr. said his Dad called it years before that moniker stuck.)

Later on, I was ONE of the guys who built the McLean design, tube direct input system/monitor which took the concept to the next level at Motown. But Motown early on had "Wolfie Boxes" which I sold to Ron Malo before Mike was there. (I later designed and built a solid state versions of Mike's idea for Golden World, Theme Productions and Bill Beltz and I improved it further for United Sound.)

(As an aside and to correct comments on some of the forums, neither I nor Russ Terrana ever used dynamics processing to record either Jamerson, Sr. nor Babbit. We would never think to alter, in any way, what was "their sound". That was ANATHEMA! Only over-egoed producers or engineers would think of that.)

In any case, in early 2010 after Dennis' interview aired, my mailbox was full of requests for the "Wolfboxes". That prompted thought of potentially building them once again.

By the spring of 2010, I had fully researched the availability of the A-11/12J. I contacted Traid Magnetics (now an offshore company) and was informed by their sales department that they were not interested in re-making the A-11/12J series transformers in small quantities. Additionally, numerous long experienced audio engineers, whom I truly respected, had also confirmed that the making of quality transformers had become a lost or "black" art (so much for new Masonic Orders).

In the 1960s and 70s knowledgeable engineers realized that all transformers introduced what is now called "character" (read "distortion") that those more politically correct call "coloration". But for impedance transformation and coupling, it was then "state of the art". In their day, the A-11/12J transformers were, based on my measurements and analysis at the time, the device of choice particularly because of their low frequency performance superior to other input transformers available in that era. I also realized that this so called "character" was the appeal of the device...and the A-11/12J transformers were the reason. (This character "thing" strays far from my audio recording philosophy, but that's another discussion...)

Continuing my research, I did cross-correlation measurements and analysis, searching for an acceptable replacement with the A-11/12J transformers in my personal "Wolfboxes" versus other good transformers of today. I additionally discovered that what set this older transformer apart was its low frequency saturation capabilities. From my discussions with others, I also was aware of the need for now hard-to-find information and materials to build these vintage transformers.

My knowledge of the materials problems of industry was enlightened by my work with Paul Klipsch (RIP) in the middle 70s and with my friendship with Dean Jensen (RIP). Again in God's providence I was good friends with both of these audio pioneers and thankfully learned much from them. Both were dealing with "magnetics" problems caused by materials. Paul had the problem with the OEM tweeters (a custom built and selected T35 from EV) and the conversion to "mud" magnets brought on by the lock down on cobalt from Zaire which eliminated the alnico magnets (Alnico = Aluminum, Nickel, and Cobalt). Dean Jensen was dealing with iron and nickel and variability from suppliers. (As an aside, my relationship with Dean started in the 70s when I was shopping for a replacement for the then disappearing A-11/12Js in the hope of continuing the "Wolfbox" with his transformers. Dean admitted to me that the low frequency performance and build quality of the formerly Chicago-area based Triad Transformer Company's A11-12J series transformer was "incredible" and that even he could not hope to duplicate it. Quality, back then, was recognized by its competition and Dean had the humility and integrity to applaud it.)

However, I am a electro-acoustic engineer, but I had some theory background from college and some practical magnetics experience from my work with magnetic tape recording head design from my work at United Sound Systems. United, with Jimmy Siracuse at the helm (earlier instrumental in the design of the Ampex 350 transport), built one of the first eight-track, one-inch recorder transports from SCRATCH, as well as all of all of our magnetic film recorders and dubbers. I learned more practical magnetic theory from my work with the tape duplicators American Sound and Tapetronics, dealing with magnetic heads and tape. All in all, my detailed transformer magnetics knowledge was limited.

But by the grace of God and my work with Fr. John Hardon, I became close friends with Frank Lum who is "THE" magnetics guy. (We are both Marion Catechists.) Switching power supplies and iron are his "thing". In fact, Frank is one of the patent holders of the first magnetic memory unit, what we now call the "Hard Drive". Thanks to Frank, "I was to be educated." I learned that much of the "magic" was in both the detailed manufacturing techniques (the lost art) and materials used.

Frank pointed out that the key element in low frequency linearity was magnetic lamination coupling (with the trick being physical texture which allows close coupling between laminations). And the key to this (brace yourselves) was MOLYBDENUM. It makes metal malleable. Frank and others I talked to later also suspected that the "moly" affected the magnetic characteristic of the metal as well.

Many of these exotic materials, in particular molybdenum, have now been restricted in mining and subsequently banned from certain industrial use in The United States because of health and environmental hazards. (I suspect this may be the reason for Dean's problems in the 70s). Interestingly, low amounts are needed in the diet FOR good health. Please see the following documentation:

And best of all, see this story about a recent "ghost town", Kitsault in Canada, as a result of the mining of molybdenum at:

There are two sides to the coin of regulation however. It appears that, thankfully, Phelps Dodge took the economic and moral high road in Kitsault. I personally believe most so-called environmental regulation is without scientific foundation and is politically motivated. Pure over-regulation for the sake of political control. In this case however, the science wins. My research showed that Molybdenum mining and processing is expensive and environmentally dangerous stuff and thus scientifically and medically problematic. Clearly, for moral and health reasons, molybdenum was out of the picture for any new quality U.S. made transformers, at least for me.

Early on, Frank suspected that molybdenum was part of the alloy and our later research involving an electron microscope and analysis at The University of Michigan, which I have on file, confirmed he was correct. The A-11/12J transformer indeed had molybdenum in the alloy, and therefore the use of new transformers with this as part of the alloy, I could not morally consider. Perhaps in Asia they may be allowed to mine and refine "moly", but thankfully not here. And if I were to build the "Wolfbox" again, it would have to be an American product, and if the key component was not American, then I terminate the project. Furthermore with this knowledge, I realized that to recreate the original "Wolfbox" without the vintage A-11/12J meeting its original performance specification and my standards would be an impossibility. The game, I held, was over...

When I shared all of this with Al at Acme Audio, being the marketer that he thankfully is, he suggested that we look for NOS (new-old stock) and scavenge the web for vintage A-11/12J transformers of the era. It would be a limited run, and because of this I agreed. Al put Heather on it.

Heather is absolutely amazing. Within a week or so she had rounded up 15 or 20 used and NOS vintage A-11/12J transformers on the web. Al wanted the new "Wolfbox" to be a "pretty" and more durable version of the original, but to basically keep the same look. I again agreed. I took the measurements from my original vintage box, built in a Bud mini-box and put my Turbo-Cad on the Acme shop computer and drafted the mechanicals. Al sent the prints to the Opticom case supplier. I was hoping this would go to a local Michigan company but he had a relationship them and we wanted to get building. Heather was busy ordering parts from my parts list and by spring of 2012 we were building "Wolfboxes".

As an observation of fact, the boxes were costly to build. Used and NOS A-11/12J transformers were commanding high prices, had to be tested and sometimes the leads extended. The plugs and jacks I spec'd were the original Switchcraft. The switches and pots were military grade. The case was well made, and with the baked enamel much more durable. The the wooden boxes were also costly, but the final quality touch in the creation. Right down to the original Bakelite knob it was a very "Pretty Wolfbox". (Unfortunately, I don't own one of these new models.)

Sue, my wife and the graphics part of Audio Graphics Services, designed a "Wolfbox" logo and authored a nice booklet (Heather's idea). Sue used some vintage pictures we own of a young Ed at United Sound (he was a handsome dude...what happened?). Al's brother-in-law Rich, who is a great product photographer, even did some photography. All first-class. But considering the number of hours I personally spent on mechanical design, consulting with Al, Sue's work, my construction of the majority of the first 25 – in addition to testing and documenting the performance –it was financially a bust, even at a sale price of $750.00.When the collective hours are considered, I was cheap labor! And it was my design, my idea, my concept. A friend called it “A labor of love.” At this point, I think not!

Al and Heather continued to look for transformers after the first batch of 25 were sold by the winter of 2012/2013. But A-11/12J prices on the web were rising, most likely because we were buying them all up and the result of supply and demand. In the spring Al located another stash of the transformers as used in older Spectra-Sonics mixers. He went to work scavenging those, among others he had found on the web. What? Another 25 to be build? Heather ordered more components and by the fall of 2013 more cases had arrived and I was back at the Acme bench.

I like building things, making things work, designing and prototyping circuits, performance confirmation and documentation, R&D, then finally...craftsmanship. But the money here was peanuts for the time committed. Lord, I have a finite time left on this earth. Is this what a you want a near 70 year old Ph. D to be doing?

I soon discovered Al had different audio and business philosophies from me. In art is there a real RIGHT way? Are the results how can it be judged. This is what I asked myself.

I've always loved music and electronics. I had my ham radio license at age 11. By 14 I had a commercial radio license and was working in broadcasting as an engineer and learning from guys four times my age. My love of math came from the lessons these great men taught, showing me practical application and theory by way of antenna directionality methods. However audio was a bigger driving force. It combined the scientific knowledge and the art of music. The whole goal, at least for me, was audio purity..."High-Fidelity". That is the science of being faithful to the original. And now from what I was observing in modern recording, the technology and use of it in recording was fast becoming a lost art. This was depressing for a number of reasons.

The most emotionally and artistically satisfying musical experience I've found has always been the live performance. In a great acoustic space it's even better. It's the "real deal" - what separates the girls from the ladies and the men from the boys! Therefore, the goal of great recording and great audio to my mind is to push the technology and audio skills to the limits, to re-create that natural "live" experience. To be "highly-faithful" to the original.

All of my audio mentors from Al Kassens, Johnny Weeks, Bob De'Orleans, Jimmy and Joe Siracuse, Bob Fine, Paul Klipsch and Rudy Van Gelder have echoed the same litany. A great recording (or great audio) is where the engineer is invisible and the musicians with all their God given gifts (and warts) appear. If the engineer did his job right and the technology was as transparent as possible, we then may achieve this elusive High-Fidelity.

The most wonderful gift of God, MUSIC, comes through humans and is either suppressed or transmitted by the use of the technology! If the engineer gets in the way, either by his use of said technology or his ego, he hurts the result. Put simply...It's the MUSIC, stupid!!! There is a moral component here too. Consumers of music have the right to expect true value from the money expended for a recorded musical experience. For the first time in history the consumers' delivery media has the capability to present the full dynamic and frequency range of human hearing with today's digital audio technology. To limit this capability either musically, dynamically or spectrally is to cheat the audio consumer.

Clearly, audio accuracy has always been the personal goal of my work and design. In audio, the purity model works…less is is always more. More processing equals more distortion. More microphones equals more comb filtering. More tracks equals more cumulative noise. More circuitry equals more distortion. Less is is always more. Another supportable fact and UN-pleasant reality for many HYPED, high end audio manufacturers is that many of the less expensive audio devices today are more accurate, lower in noise, distortion and overall performance than the vintage devices of yesterday. (However, the newer cheap stuff may be crafted poorly.) The sonic result depends on the skill of the user.

And it's interesting to note that PRICE has very little to do audio quality. Contemporary resistors and capacitors are generally less expensive, lower in noise, more accurate in value and more durable than the earlier "vintage" components. There are no good or bad "ohms" or "farads". The key is the circuit integrity and well it is designed.

Considering the "Wolfbox", the reality is that there's nothing magical about it. The perceived "character" and (in truth the "distortion") is a result of the A-11/12J transformers. The design goal was to couple an UN-balanced output of different amplitudes and impedances to a balanced microphone input at 150/250 ohms. (Low noise is only possible at low impedances hence the 150/250 ohm tap was chosen as best when coupling to electronic balanced inputs, which were becoming popular at the time, as well as for matched transformer mike inputs.) Using a mike to grid input transformers in reverse, with resistive attenuation, was an elegant solution to this matching problem. At that time the Triad A-11/12j was the purest most high-fidelity transformer I could find.

Transformers really are a sonically impure “blast from the past.” Today there are FAR more elegant ways to couple devices other than transformers. A balanced line can be coupled with a dual op-amp line driver. The microphone input stage can be a compound pair of NPN/PNP low noise transistors for common mode rejection driving a low noise op-amp. All with better coupling, transient response, square wave response than a transformer input or output device. If RF is a problem use a ferrite bead. The result is greater transparency and purity.

I had been working on a high fidelity, active solution "Wolfbox" since the late 1970s but never spent much time on a creative end. Then in 2008, long before I had any association with Acme Audio, I came on clever solution. I had protected this design when I presented to Al my new electronic active, phantom powered solution as the next "Wolfbox". He thought it was good but soon brought up the "character" issue. Right then I feared our two philosophies were UN-complementary.

Same thing happened with the "United EQ". Right away he wanted to transformer couple. In fact when he built the prototype from my design (and without my authorization) he hung transformers on it. It was designed as an active input and output device for the reasons above. In talking about the United Sound/Les Cooley designed Class A console, his interest was in the Cooley transformer coupled mike pre-amp. When I showed him my super clean "wire with gain" design, he again feigned interest. It seemed I wanted to build a Porsche on steroids, and he wanted a vintage Model A.

Still I wondered if this was because of the strong marketer in him (and hype value) or because he just did not understand? In any case I quickly realized that the relationship would not endure. There is no right or wrong here. Just a difference in audio and business philosophies. (In business I am NOT a capitalist but a distributionist.)

But had I given my word to build the last 25 "Wolfboxes" and while waiting for the transformer brackets and the transformers, I set about mounting the rest of the components and cleaning up the grounding points in the newly arrived cases. I did this for about a week (while Al was out on another project) until I ran out of parts. I left him voicemails telling him of the situation. I checked back in the shop about a week later to discover the the boxes I had mounted with parts were gone. It appears that Al had changed the terms of our agreement.

Sue kept pointing out how working at Acme had become so depressing to me and I was still mentally wrestling with how I could keep a friendship, and tell Al that it was best that we part ways. God solved that problem for me.

Al called around the second week in November and essentially ordered me, in the manner in which it was done, to come over and certify the 25 "Wolfboxes" that he had sent off to be built. I pointed out to him that I was NOT going to certify the performance of devices that I did not build nor supervise the construction of, and further asked why contrary to our agreement he had the devices built elsewhere.

I was then accused of many things, including not being around (I was around) and running off to do another project of my own without finishing this commitment. So I pointed out that he himself was off with other projects and (per voicemails) that the final parts were not present, and subsequently questioned why HE could be absent and I not exempt? Further, I inquired what permitted him to alter our agreement and make decisions about the "Wolfbox" construction without my authorization? His next words were – and I will remember this forever, as I was so surprised – "You are not going to take this away from me!"

I kept thinking to myself, who's idea was this anyway? I simply said, "I'm out, this is over." I hung up. I have not spoken to him since nor do I intend to.

As a mixer/producer and a GREAT audio marketer, I respect Al. The Acme Opticom is unquestionably a great vintage tube limiter. I wish him success. But I cannot deny that I am very upset about the situation and the discovery of the UN-authorized manufacturing & marketing of the "Wolfbox" under a different name with the potential of a new transformer that may have molybdenum in its alloy and the moral issues there. We discussed a new transformer as a possibility in 2013 and I made no secret of my concern. Morally, this matter is such that I discussed it with my confessor so the real reason for this document is to protect my ethics, my name, and give you my perspective on this sad situation.

(You have hopefully followed the story up to this point. So now let me change direction a little, offer you a ray of sunshine, a PLUM for your patience…the CODA if you will.)

The reality is that God really gave me all my abilities, gifts, skills, thoughts, ideas and circuits to use for His Honor and Glory, not mine. I had nothing to do with it. And while I am not wealthy nor never hope to be, I have never been hungry or without a roof over my head. God has never let me down.

The "Wolfbox" cannot, and will not, give you the tone and amplitude consistency of James Jamerson, Sr. or Jr. Nor will it give you Bob Babbit's transient control. It will not give you the precision of Chris Lopes. Nor will it will not give you the the chops of Eddie Willis or the crying wah-wah of Dennis Coffey. No, you won't have the bite of Paul Lamb. All of that is PURE HYPE. What it will give you however is clean, unsaturated, realistic reproduction of the input instrument with the best of 60s and 70s era technology. The rest is up to you and your skills.

So it is therefore in the spirit of the Detroit audio business as it was when I came up, and with the hope that the tradition of the studio owner/engineer/craftsman will continue, you will find the link below to the .pdf file schematic of the “Wolfbox” for your own non-commercial use. Build it. Package it as you wish. Play around with different input transformers, new (without “Moly,” I pray.) and vintage. Learn how to make reciprocity analysis of the differences. You will discover that your ears are variable and far from an accurate and consistent method for analysis. You'll gain much knowledge and insight from the experience.

Above all, have fun! Make GOOD music and thank God for the skills he has given you. And if the mood strikes, send me pictures of your packaging. I'm eager to see (and maybe even hear) your results!

Thank you greatly for your time.

Ed Wolfrum

NOTE: The “Wolfbox” is essentially in the public domain, other than the new attenuation network that I designed and was completed at Audio Graphic Services. That part is protected but will now be released under the Creative Commons license for non-commercial use.

Download Wolfbox Schematic in ,pdf format

Wolfbox DI Circuit by Edward J. Wolfrum is licensed under a
Creative Commons Attribution-NonCommercial 4.0 International License.

© 2014 Edward J. Wolfrum, All Rights Reserved