About Me, Joe Rasmussen
"Listening means everything, talk is cheap."
Introduction
Hi, my name is Joe
Rasmussen.
This page introducing
myself goes a bit against the grain. I am not much of a self-promoter, but
I have come to realise that to sell what I do, I also have to sell myself.
It comes down to the personal touch, people want to know something about
the person and what makes him tick.
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 Allen Wright 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 (so far) 32 year association.
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 (ear?)
tuned by the late Rowan McCombe whom Allen affectionately calls
'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 past 2AM in the morning,
the beast was tamed. It used no negative feedback, which was unheard in
Hitachi MOS-Fet amps. Vacuum State build 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 RTP (see below) 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 (Real Time Preamp). 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 prefer 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. Both FVP (Australia) and SVP (Swiss made by
Vacuum State) are now SOA preamps in their own right, and 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
contact me for advice.
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.
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 (look it up in a dictionary). 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 plumbers equipment in my hands would lead to
disaster. As Dirty Harry said, "a man has got to know his limitations."
I have had two major
collaborators in Michael Lenehan of Lenehan Acoustics and Brad Serhan of
Orpheus Loudspeakers. I have shared freely my '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. Marriage, in the form of committing to commercial
production, is not far away.
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.
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. The only drawback, similarly with the first
generation Sony SACD Players is the low output, if you use a proper preamp, then no problems. These were sold
under the moniker JLTi.
Analog Again
Next of the block was
going 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 a the Tweeter.
The result is now
available as the LEM, Linearity Enhancement Module, and can be fitted to
just about any tube power amplifier. What is intriguing is that it also
improves some solid stage amplifiers.
If you have a Tube
Power Amplifier of any type, but especially Push-Pull, contact me about
having the LEM installed. If you have a Solid-State Amplifier, the
potential improvement is open to discussion. For Tubes, go for it!
Digital Again
Well, not exactly. 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. It is that ill-mannered circuit contraption
called the Current-to-Voltage Converter, or I/V Converter for short. But
finally we came up with a potential solution.
The usual way to
convert the current to voltage is called 'active' - it consists of a
'virtual earth' and is created to a circuit block (usually an IC Opamp)
with grounded Non-Inverted input, the Inverted input thus becomes the
'virtual earth.' Problem is that using Opamp technique means lots of
Feedback. The loop stability is highly questionable in a significantly RF
polluted environment. Besides, I have often seen AC signal levels with an
Oscilloscope connected to the 'virtual earth' - so why not allow for a
small AC signal and use our JLTi Moving Coil Preamp technology, but
without RIAA EQ, to amplify a small signal developed across a small
resistive value similar to the impedance of a Moving Coil cartridge. This
bit of lateral thinking was applied in a differential current cancellation
manner across two resistors that are trimmed and grounded for accurate AC
balance. No 'virtual earth' and no negative feedback. Totally immune to RF
and ultra-sonic slew rate induced distortion.
This solution cracked
a six-year-old problem. And the result is truly everything that could be
asked for. We are now able to do all types of digital players - new
generation clock/power supply, noise floor suppression and non-opamp audio
outputs.
Now and The Future
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 six years and also loves the cream coloured (a la Jeff
Beck) Fender Strat Squier I bought him. It should have been Fiesta-Red
Pink Strat a la Hank Marvin.
In the last decade I
have travelled regularly to Europe, attending the European Triode
Festival, meeting up with Allen Wright at Vacuum State (now in
Switzerland) and seeing relatives in Denmark. Allen likewise comes to
Australia regularly and meets up with friends in our house.
Visitors are 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 our latest
developments etc. It is as they say, listening means everything, talk is
cheap.
Joe R.
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