About Joe Rasmussen

133 Dalmeny Drive, Prestons NSW 2170, Australia +612-96074650 & 0412-203382

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Telephone
612-9607-4650  (02-96074650)
Mobile Phone
61-4122-03382  (0412-203382)
Fax
612-9034-9666  (02-9034-9666)
Postal address
133 Dalmeny Drive, San Marino Estate, Prestons 2170, Australia
Electronic mail
Webmaster: joeras@vacuumstate.com  

Introduction

Hi, my name is Joe Rasmussen.

The Early Years

I was born in Denmark in the inner suburb of Frederiksberg in Copenhagen. As a cultural centre, Copenhagen is unmatched in the north of Europe. My Father was considered a young wiz kid and snapped up by the DR, the Danish Broadcasting Corporation, to head the Dubbing Department (which is responsible for the sound accompanying the vision). He was both an electronics and recording engineer as well as a recognised expert on acoustics. Those early days of TV were heady days and as entertainment began to exploit the new medium, my Father got to work with some of the most famous acts in the world in the late fifties and the sixties, as well as making several movies including the landmark Hamlet at the Castle of Elsinore starring Christopher Plummer, Robert Shaw and Michael Caine plus other highlights like the The Beatles at The Tivoli and Euro Vision Song Contest . These were my pre-teen and teen years and they were happy days.

In 1965 we moved as a family to Australia. My father did commercial TV production and finally ended up at the ABC, the Australian Broadcasting Corporation. He died tragically in an accident in 1974.

Out On My Own

By this time I had left school, had toyed with the idea of an IT profession but ended up working for HACO-Hagemeyer in  their Parts & Service Department. My job as consultant was as a liaison between the technicians doing mostly warranty work and controlling parts supply and ordering from Japan. The brands were Technics, Panasonic (National) and JVC.

I met the late Allen Wright (1947-2011) in 1975 at a Hi-Fi Show at The Pavilion in Sydney Showgrounds. The Pavilion has since been converted to a large movie studio where the Matrix movies were shot as well as the last two Star Wars movies. Allen was demoing stacked Quads and was the sound of the show by a country mile. This started a 36 year association that sadly ended in 2011.

I shortly afterward met up with Allen in his Wentworth Avenue premises to order a Decca cartridge to be upgraded by the late Garrott Brothers and hand (or ear?) tuned by the late Rowan McCombe whom Allen affectionately called 'The Guru.'

We ended up doing so many projects together that my head starts spinning trying to remember them all. While my first love had always been speaker design, I found myself working on tube power amps, specifically hybrids combining tubes (valves) in the front-end and using the new-fangled MOS-FET devices from Hitachi. Rowan suggested a particular method of boosting the lack of transconductance (gm) of MOS-FETS, but the problem was that the idea also made a near ideal oscillator. These new devices were supposed to be near indestructible, don't believe it. I blew them up by the bucket loads, but in the process, often working to the early hours in the morning, the beast was tamed. It used no negative feedback, which was unheard in Hitachi MOS-FET amps. Vacuum State built a number of these in mono-block versions for customers, but only on order.

I also started experiments on old Dynaco tube amps - and one was using the gain stage of the Real-Time Preamp, or RTP, and adapting it as a front-end, combined voltage stage and phase splitter. The result of this, with a Triode mode output stage, is to reverberate to this day and is the basic principle our tube power amps works on to this day.

So I was focussing on power amps, in the meantime Allen was  concentrating of preamps (two of them) what eventually became the RTP and there would also be a low cost preamp (developed from upgrading Quad preamps) called the FVP (Four Valve Preamp). Both the RTP and FVP (the latest incarnation is called SVP) developed to the point where the FVP no longer was a budget preamp, but the single-ended variant and the RTP was the differential version (we preferred this description over 'balanced').

The early eighties were lean times; except for getting married to Tina (we now have three boys). But by mid-eighties things were gradually starting to look up. Around this time I was doing custom tube work for recording studios as well as maintenance. This included microphone preamps, tube compressors, tube DI boxes and mixers. Around this time we also did a custom RTP preamp for A. J. Van den Hul, which he ordered during a visit to Australia. The FVP went into production. A PCB only version was sent to Matthew Bond of Tara Labs (the cable company) and was inserted into a box design of their own. This became The Passage Tube Preamp and included a Moving Coil Phono Stage. Samples were sold is the US and Asia. We still get inquiries about these.

The FVP preamp took on a remarkable life on its own, especially here in Australia. After Allen went to Europe in 1992 (from memory), it was found that the improvements of the newer FVPs could be incorporated into older FVPs, such is the versatility of the design. That is why there are a number of people who have had FVPs for two decades. Hundreds of FVPs can be updated to sublime performance. If you can pick up one second hand at the usual low price (the seller doesn't understand its value), then it can be brought up-to-date for reasonable dollars.

A Major Diversion

Because of committing to a mortgage and expanding family, I had to find reliable full-time work at a time when we had a recovering economy. I went into the transport business for a decade but continued having a 'finger in the pie' audio wise. Never stopped working on audio.

My focus was also shifting. I never hide the fact that speaker design was my first love, one that I did not really do for profit. But this has been a tortuous road to travel. Speaker design is a form of masochism. It is also an extreme form of discipline, especially if you venture into computer modelling. High quality hardware and software has increased in power and reduced in costs. But these are tools and like all tools, it is the wielder of them that matters most. I am sure plumber’s equipment in my hands would lead to disaster. As Dirty Harry said, "a man has got to know his limitations."

I have had fellow speaker designer compatriots in Michael Lenehan of Lenehan Acoustics and Brad Serhan of Orpheus Loudspeakers. I have shared freely 'discoveries' and also used them as sounding boards, especially to see if they could punch holes in my theory or application. As something I did for love, it has now become a serious affair.

Father of the Buffered Gainclone

Going back to an older topic: Power Amps. But in this case, applying this as an Integrated Amplifier. I was approached by a friend who had been reading about so-called 'Gainclones' on www.diyaudio.com . This DIY concept born out from the use of National Overture Power ICs as used by 47 Labs of Japan and others. My friend did not have the necessary DIY skills to build a Gainclone and hired my help. This obscure technology became a minor obsession as I could see the balance of high performance and reasonable cost. But I also perceived that 'inverted' Gainclones needed a so-called Buffer in front of it. Here was the birth of the Gainclone Buffer that is now used by DIY constructors throughout the world. Just do a Google search on the subject buffer gainclone.

That started out a minor craze in Buffers as it was realised they could facilitate better sound.

But not just being the person who fathered the subject of the Buffered Gainclone, I did suggest the use of a tube buffer. This eventually took on a simple DIY project and also a commercial project called the JLTi Hybrid Tube Integrated Amplifier.

But Buffered Gainclones now abound, whether they be tube, IC or discrete component buffers, they all originated from this concept that I developed, the buffered Gainclone. The common expression that the Buffer fleshes out the sound, more relaxed and with my suggested LPF (Low Pass Filter) the soundstage is also enhanced. That is my legacy to the DIY audio fraternity, well, one of them. There was more to come on the speaker front.

Going Digital From A Vinyl Background

Around 2001 Allen developed an upgrade module to suit the first generation Sony SACD Players. This took the DSD signal from the VC24 Digital Filter and buffered and processed it. Later I worked on lowering power supply noise and Allen joined in and together achieved the result we wanted. Next was a major improvement in the Clock, particularly in developing an ultra-low noise power supply.

We needed to look beyond these players alone and the new generation of multi-players beckoned. This became my lot, to determine which players were suitable and developing an upgrade program. These players generally use 'Voltage DACs' where no I/V (Current to Voltage Converter) is required. Our Clock Technology, noise suppression and a custom output stage that required no ICs and no voltage boost. These were sold under the moniker JLTi.

Analog Again

Back to analog, Allen had identified a particular device used for video purposes, low noise, no internal compensation and no feedback required. As its noise specification was suitably low with low source impedance, a la Moving Coil cartridges, it was decided this could potentially make for an interesting Moving Coil Phono Stage. As Allen was busy with moving his business from Munich in Germany to Switzerland, I took it upon myself to do the actual development and produce working proto-types. Some of these were dispersed locally here in Australia and also a number of them went to the US, the first going to Roger S. Gordon, reviewer for Positive Feedback.

Eventually the production of the phono stage went to Switzerland using much fancier metalwork. It was also given the name JLTi Phono, where JLTi stands for Just Listen To It. On a cost versus performance, its audio quality is unmatched, and that is not just our opinion. See Positive Feedback Review.

Revisiting Tubes

During a discussion by Menno Vanderveen during the European Triode Festival in 2006, the problems troubling the designer of audio transformers were highlighted. This included memory (hysteresis) and permeability, which is the ability of the signal to transfer from the primary to secondary in tact. This directly related to the density or degree of magnetisation. The real problem here is that permeability is reliant on a healthy signal level. Yet the dynamic nature of music contains very low levels at the beginning and end of a transient.

Further private discussions with Menno and I suggested a solution that takes advantage of the excess bandwidth of the output transformer. A method of exciting the transformer well above hearing range and yet low enough not to cause damage further down the line, such as the Tweeter.

The result is now available as the LEM, Linearity Enhancement Module.

If you have a Tube Power Amplifier of any type, but especially Push-Pull, contact me about having the LEM installed. It can also be converted to Virtual Triode Operation, which perfectly compliments the LEM.

Digital Again

We forget that digital players have an analog side to them - and that is what we connect our Interconnects to on the rear panel.

We had been avoiding players with Current DACs for some. It needs to be a Current-to-Voltage Converter, or I/V Converter for short. Very tricky indeed.

But finally we came up with a potential solution based on “Diamond Transistor” device. Our own I/V Converter Module is now a reality and will find its way into players like the latest models from Oppo with Sabre DACs and Yamaha, Sony and more, using Burr-Brown DACs.

Now and The Future

Commercial speaker design with a famous name. The latest Oppo BluRay Players are amazing, especially the Oppo BDP-95, now the Best Player I have ever heard with “SAW” Clocking.

As a family we continue to live in the South-West of Sydney where we have a two-story house. The front of the house contains my work-shop, dedicated sound room and storage. The immediate outdoors in front also doubles up as acoustic measurement area for capturing data to model loudspeakers.

My boys are all interested in music, playing a number instruments such as piano, acoustic and electric guitars and clarinet. My oldest has been studying Spanish Guitar for nearly eight years and number two plays piano and keyboards as well as electric guitar.

In the last decade I have travelled regularly to Europe, attending the European Triode Festival, meeting up with Allen Wright at Vacuum State (next time going to Europe is not going to be the same) and seeing relatives in Denmark and an errant brother in Norway.

Visitors here are always welcome. I am here most of the time, so please do not hesitate to give me the opportunity to play host for an hour or two, demonstrating latest developments etc. It is as they say, listening means everything, and talk is cheap. Let the ear be the final arbiter.

Joe R.

 


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Copyright © 2003-10 Joe Rasmussen & JLTi
Last modified: Monday June 08, 2015

Just had a terrible thought. If "intelligent design" is unscientific, then who will design our audio equipment?