Stephen Mantz: South African born audio legend (Part 1)

Orcish75

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Sorry, I have to split this in two.

After the huge improvement my Rotel RB-985 displayed when Nilam serviced it, I decided that the same should be done to my Harman Kardon Citation 7.1 amp. The HK is about the same age as the Rotel, from the mid to late nineties. I downloaded the service manual, hoping to find the biasing info for the amp, but unfortunately, there was no info on it. I searched further on the Internet but found no additional information. The searches lead to me finding out that Stephen Mantz designed it for Harman Kardon. I tracked down that Stephen owns Zed Audio and found his email address.

I fired off a mail to him, hoping that he?d reply and the next day, true as bob, a mail was sitting in my inbox from him. I mentioned that I was from South Africa and he replied that he used to live in Parktown and left for the States in 1983. Such a small world!!! He was really friendly and wrote down all the steps to bias the amp as well as a mod to allow more current to the speakers before the protection kicks in.

I sent the amp to Nilam with all the details so that he could service it. Nilam mentioned that it was one of the best designed and constructed amps he?s worked on. After 20 odd years, the bias was still spot on, on all the channels. I was really happy to hear that.

I chatted to Stephen a few more times and he kindly allowed me to share his audio journey with us. It?s even more fascinating as he grew up in JHB and his love for audio started here. He pioneered many innovations, especially in car audio. He has designed for Harman Kardon, Polk Audio, Rockford Fosgate and others.


It?s a long read, but well worth it!


I was born in Johannesburg, South Africa and grew up in a middle class suburb (cities in USA). Lived a pretty normal childhood until IT happened. At the age of about ten, I was with a childhood friend who was born on the same day as I was and we were at his house one day. When his older brother told us to come into his bedroom to see something. Well this something was to change my life. In his bedroom he had one of those table top tube AM radios (FM had not arrived in South Africa at that time), and he had removed the internal speaker and mounted it on the ceiling of his bedroom at the point where two of the walls met. By turning the volume knob on the radio he was able to adjust the level in the loudspeaker. I was in awe! Imagine turning a knob on the radio and the sound came out of a speaker 20 feet away. I had never seen or heard this before.

When I arrived home that evening, I immediately went to my Aunt, who lived with us, and begged and pleaded with her to hand over her small table top AM radio. Well she finally gave in and I had my prize. Now remember at this time I had no idea what a resistor, capacitor or tube was or did. All I knew was that I had to remove the speaker thing and put it as far away from the radio as I could. By the way these table top radios did not have isolation transformers instead they used high voltage tube filaments which were wired in series across the 220v mains supply. Also the chassis was live if the power cord was reversed and I found this out the hard way. I begged, borrowed and stole some surplus copper wire from various sources and then proceeded to connect the wires in the radio to the terminals on the speaker.

No soldering iron at this time so twisting was the order of the day. At each join I simply used scotch tape to keep the joined wire pieces from moving around. At this time I had no idea what insulation tape was. Turning on the radio for my first test was a big disappointment. No sound came out of the speaker. After much frustration I finally figured out that at each join it was not a good idea for the speaker wires to short to each other!  Progress at last.

Next test was successful. Calling my Mom, Dad, Sister and Nanny into my bedroom I showed them my sound system. I was so proud. Well the true engineer was now born within me. I was soon bored with just this one speaker and started scouring friend's houses for discarded radios and radiograms (those things with an AM radio and a 78RPM turntable all in one piece of furniture, kind of looked like the JBL Paragon speaker system). Soon I had about seven or eight speakers all wired up and the sound was awesome (speaker impedance was at that time something I was not aware existed). I added a small 3.5 inch reel-to-reel tape recorder to the system, (which a good friend of my Dad had donated to my cause) and then built a complete console which housed the original AM radio, the tape machine and about a dozen toggle switches which controlled about a dozen different coloured lights located in strategic positions around my bedroom. The place looked like a house of ill repute by the time I had finished. I was able to switch over the complete speaker system from the radio to the tape machine with a switch so I could listen to either Well progress had to be made and I heard about a thing called an amplifier. I read some books and started learning about amplifiers. I had a friend whose Dad owned a radio repair shop and so with my life savings of nine bucks, I bought the necessary parts to build a 3 watt mono amp.

I had rather rudimentary tools and so I built the first one using pressed wood as the chassis. It worked first time but the hum was probably louder than the music. Further reading brought me to the conclusion that a metal chassis was required. Off to the kitchen to hijack a metal tin which housed four pounds of Bakers English biscuits. I persuaded my Nanny to put the biscuits in another container. The tin was made of tin (no pun intended) and so was pretty easy to cut. I rebuilt the amplifier on this and it worked like a charm. At this time I began reading as many technical books as I could get my hands on. Ohm's Law became second nature to me. Woofers, midrange and tweeters were soon a well-known idea to me and stereo was my next project.

I built a 10-watt per channel Mullard circuit, but now used chassis bought from my friend's radio shop. Progressed to a 20 watt per channel and then my interest in radio transmitters began. My best thing to do was to broadcast Rolling Stones (my all-time favourite band) music over the FM band. I had three and four Kilowatt transmitters running with a huge antenna hanging out of my fourth floor bedroom window (at this time we had moved into a flat (Apartment to Americans). This was 1966 and I started to design my own amplifiers.  1968 was the year that I switched from tubes to solid state amplifiers. Quad and Dynaco were popular but were not very powerful. So I began my quest for power.  The arrival of the Crown DC300 pro amplifier rated at 150w per channel gave me inspiration to design. One hundred watts per channel, one hundred and fifty watts per channel were the order of the day.

The owner of an electronic spares shop downtown Johannesburg became interested in me and I was soon building these powerful (for their day) amplifiers for his store. Graduated high school 1968 spent a year working and messing around until I started University in January of 1970. 1969 was the year in which I was supposed to go to the army for my 9 months of compulsory military service. I squirmed my way out of that one and this gave me a year to really learn a lot about amplifiers. I gave up on my High Current Electrical degree at University after one year as they were teaching me a lot about nothing. A friend, who actually completed the 5 years at University, told me that he knew less than me after those 5 years and wished that he could have done what I had. I went to college to study pure electronics. This was a four-year course, which included 2 years of hands on training. The first two years of theory was breeze for me, as I already knew this stuff from own studies.

I wanted to leave but my folks insisted that I get "the piece of paper".  After college the United States Government offered me a job at the Hartebeeshoek Space Tracking Station. (I know that you may get your tongue in a knot trying to pronounce this Afrikaans name so do not even attempt it!) This was great as you worked 4 days on and then 4 days off. The problem was that the station was in the middle of nowhere and the pay was awful. So I refused the job.  Then the CSIR (This organization is like the UL/CSA/EPA all rolled into one and they govern everything that could be made and sold in South Africa), offered me a position as a research engineer. The pay was 220 bucks a month out of which they took medical, tax and some other deductions, which would have left me with 160 bucks a month. "No thank you" I said! I took a job at a Sanyo factory repairing the cassette machines as they came of the production line.

After 3 weeks I was bored and started my own company. I decided to get a Bachelor of Science degree through UNISA which is the largest correspondence university in the world. I built mainly professional gear, including mixing consoles, compressors, limiters, equalizers and of course my all-time favourite, amplifiers. January of 1972 I began the design of a 1,500-watt per channel 8 ohm home amplifier. This took me 18 months of work and finally in June of 1973 it was complete. It utilized a 5.5 Kilowatt power transformer and used thirty two, 250 watt TO-3 power transistors per channel. This represents a total of 8 Kilowatts of output capability per channel. The beast weighed in at just on 91 Kilograms (220lbs). My mother decided to nickname the amplifier Baby.  Baby remained its name until a few years later when I replaced the twin VU meters with twin 32 segment LED displays and replaced the original silver front panel with a back version.

The amplifier then had a name change to Leviathan. I sold the amplifier just before I immigrated to the States in 1983. So from 1972 until I left South Africa in 1983 I built professional gear almost exclusively. From 1971 I became in involved with live sound re-enforcement. A friend and I started a company which, hired out me as the audio engineer and the equipment. We started with smaller venues and as we added equipment to our systems, we progressed to larger and larger venues. This business grew so quickly and the fact that I travelled a lot, meant that I neglected my small manufacturing business. I did this for 4 years and then decided to quit and concentrate on the manufacturing 100%. I did get to meet quite a few English and American rock and rollers but the highlight of this part of my career was meeting the late Elizabeth Taylor when she appeared alongside the American all girl group, The Three Degrees.

This was in fact a one night gig. I will never forget meeting Miss Taylor and seeing those perfect features and her violet eyes (Yes violet - no contacts). During 1975 I was awarded a contract to install sound equipment at the newly built Baxter Theatre at the University of Cape Town. Since I lived in Johannesburg, which is 2 hours flight time from Cape Town, I was constantly shuttling between the two cities for the next year. It was quite an achievement to design and install sound systems in two adjacent theatres. In addition I designed all the communications gear for stage managers to communicate with dressing rooms, ticket office, theatre manager etc. This took me almost one year to complete.

1976 I decided to take a course in Television design and completed this in about 6 months but my basic knowledge of TV now is to take the remote and turn to the channel I want to view! The most sophisticated project I undertook was the design, manufacture and installation of a simultaneous language translation system in two adjacent conference halls at the above mentioned CSIR headquarters in the capitol city of Pretoria. The first conference hall housed 500 delegates and the second 120. Each seat had a microphone and a control panel. The delegates could select any one of four different translations of the spoken language in addition to the spoken language. The translation booths each had 4 seats for the translators. Each seat had a control box, which was in fact a simple analogue computer.

This project consumed another 9 months of time. 1972 when I fitted a small cassette machine to my Toyota Corona and built some small amplifiers using a famous pair of Germanium power transistors. (4 watt per channel was the order of the day).  Late 1975 I purchased my first BMW car, a 5 series 525. I had taken a real interest in car sound at this time. The BMW was my first real attempt at some decent sound in the car. My home stereo was already at the top of it's game with open reel Teac machines, Nakamichi cassette machines, fancy turntable, custom preamplifier and of course Baby/Leviathan. I wanted more power than the measly 4 watts and so I resorted to some early Pioneer amps, which delivered a true 18 watts per channel. Subwoofers in a car were still down the road and so 6x9's on the rear deck and 6" coaxials in the front doors along with Pioneer TS3 tweeters were quickly installed in the BMW.

A highly modified Teac car cassette machine was added and the highlight of the system was a 5 band graphic equalizer with a homebuilt Dolby type B noise reduction preamplifier. At that time Dolby was not available in car cassette machines. 1978 and I sold the 525 and purchased the new 7 series BMW, a 728. (Hated this car and kept it for 365 days due to it being silver!) Again subs were not around but Dolby cassette machines were. I again built a custom preamplifier for the centre dash. This had 14 band graphic equalizer, volume, fader and balance controls. I had begun building car amps for the home market by this time under the name Titan. I built two versions, a 60w/ch and a 100w/ch. They sold like hot cakes, as there was nothing remotely close. The only imports were the Sanyo, Jenzen and Fosgate amplifiers. They were much more expensive due to the 45% import duty. After selling the BMW 728 I traded up to the 733i and simply transferred the system over but added more powerful amplifiers at 200 watts per channel (at that time an unheard of item anywhere in the world) 1980 brought me to America to see my first CES show in Chicago . This was indeed an eye opener for me to see so much gear all in one place.  A funny thing happened, I met an old acquaintance, Helmut Stieglitz, at the Visonik booth. He had lived in South Africa and came to the USA in 1977.

We got to talking about car sound and he was really amazed at what I was doing back home. He told me that he wanted to leave Visonik/Alphasonik and start his own company.  A few trips back and for from South Africa to the USA and I began manufacturing car amplifiers under the name of Hifonics.  This name was not a really high-end sounding name after all and so I sat down one Saturday at the factory and put a little thought into it.  I had a professional line of amplifiers on the local market and instead of model numbers, I gave them names. My 800 watt pro amp was called CYCLOPS. The half power version was called, you guessed it, SON OF CYCLOPS. So out came the Greek, Nordic and whichever other ancient culture I could think about and I wrote a whole bunch of names down.  I presented my ideas to Helmut who endorsed them enthusiastically and I began the design of these amplifiers. This is when Vulcan, Odin and Thor were born.

These were the first three amplifiers, which I built for Hifonics. 40w/ch, 60w/ch and 100w/ch were their power ratings. I had been making plans to come live in the USA for many years and Helmut knew of my plan. He begged me to come and live in New Jersey, where he was based. The East coast had no appeal for me and I told him that I would live in Southern California. On arriving in the USA in August 1983 we began a small manufacturing company Zed Audio Corporation which I had formed more than a year prior to my 1983 arrival. We started building the second generation of these first three Hifonics amplifiers and added the fourth called Zeus.  Zeus started out as a 200w/ch and when Zed ceased manufacturing for Hifonics. In 1994 it was a 350w/ch.  Zed and Hifonics started growing like wild fire since we were producing equipment which was ahead of it's time and nobody could compete with Hifonics in sound quality or power.

At the January CES in Las Vegas I used my then new BMW 735i which I had brought with me from South Africa, to show off the Hifonics equipment.  It was a hit. Two 12 inch Becker subs, a host of Dynaudio midrange and tweeters and of course 5 Zeus amplifiers.  For this car I had made a new preamplifier, (which I still have today after I sold the car) which sported a 14-band equalizer, 4 channel 10 segment LED displays, volume and fader controls and a DBX unit. I always preferred cassettes to CDs as I wanted to record my own music especially that from my vinyl collection. I used I highly modified Pioneer KEX70 head unit and later switched to a Clarion. The noise performance with DBX was pretty close to that of a CD. After the show we could not keep up with incoming orders, remember we were a small company with only 3 people. We began building for Autotek in 1985, then for Rodek then Lanzar in 1988. Also built some high end amplifiers for Alphasonik in the mid-eighties. Built for Planet Audio/Boss from 1997 to 2000.
 

Orcish75

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The Early Years

Zed Audio was formed in the summer of 1983. The company began building product during October of that year. I had been exporting car stereo amplifiers to the USA for about 2 years, prior to my coming to settle here. The company for which we were designing and manufacturing was Hifonics (you remember all those funny names (Thor, Odin, Zeus, Colossus) they were the trademark of this company. Amplifiers in those early days of car stereo were usually hampered by low power, ugly cosmetics and unreliability but not necessarily in that order. My background was in professional sound and recording studios. High powered amplifiers were not new to me.

During the early 1980s the power race in the car began just as in home stereo during 1971. Zed was the first company to build a 200w per channel car amplifier in December1983, this was the first generation of Hifonics Zeus.

1985 we built the first true 3 band parametric equalizer in a dash mount chassis.
1986 we built the first one third octave equalizer.
1986 we built the then highest powered amplifier, Colossus, at 600w per channel.
1986 we built the first multi-channel amplifier with on board variable frequency crossovers.
1987 we built the first 6 channel amplifier with on board variable frequency crossovers.

During the next 20 years Zed manufactured for several car audio companies as well as some home stereo companies. We also produced guitar amplifiers for a while but the music industry was not one in which we wanted to remain so I opted out of that enterprise.

During 2003 guys were asking me why we did not bring out our own line of amplifiers. I thought about this for a few months and then we made the decision to take 'the plunge'
We wanted to develop a line of amplifiers which was of the highest quality in terms of sound, ultra-reliable and had more of an industrial look. I hope that I have achieved all three. I spent the better part of nine months designing and listening to a few designs and then settled on what we are producing today. All of my listening was done on my home system which of course does not suffer from many of the problems which plague car systems.

In the spring of 2009, we made a decision to bring to market a range of ultralight, efficient and very high quality amplifiers. These were introduced in late August of 2009. The first two amplifiers, KRONOS a rather unique 2 channel offering and LEVIATHAN a 6 channel with an output of 150w x 6.

The line expanded to include DRACONIA rated at 175w x 4 and MINOTAUR rated at 750w x 1. LEVIATHAN had a power increase to 190W x 6 and we added RA a rather unique subwoofer preamplifier which contains a Sub harmonic Synthesizer and a variable threshold compressor.
 

Orcish75

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Family_Dog said:
Orcish, I merged the two topics so that they remain "together", a most interesting read!

-F_D

Thanks F_D!  :thumbs:

I tried to do it in one shot, but it was above the 20 000 character limit and had to split it.
 

gapco

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Lukas Louw a Kempton Park resident accompanied Stephen to L.A in 1983. Lukas was instrumental in designing car audio products for Soundstream and Cadance to mention a few. Stephen owned Audio Labs Pty Ltd which was based in Cape York House downtown Jhb where Lukas was his right hand man. Lukas sadly passed away in November 2020. For a short time I imported and distributed some of Hifonics products.

Hifonics was also a S.A. company owned by Helmut Stiglitz a German national residing in Jhb. In fact he owned a HiFi retail outlet that was in End street, Jhb. He left S.A and settled in the US and so began the production of car audio amplifiers for Hifonics USA.

Stephen produced many P.A. amplifiers used in sports venues,namely Ellis Park rugby stadium. Name of that amp was Cyclops. I still have the hand drawn schematic diagrams for that one and a few others.

Stephen also modded a pair of Macintosh MC 3500 valve amplifiers which he later sold. Somewhere on the web is the mods done to these amps.

Yep we have had some really knowledgeable people in S.A.
 
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