|In response to the outpouring of e-mails and phone calls
we have received
regarding the re-issue of the PDI-03, the original designer
Martin Schmitz, has graciously agreed to answer your questions.
Now you know everything we do!
JAMS Audio www.palmergear.com
INTERVIEW WITH MARTIN SCHMITZ - May 25, 2005
Would you tell us a little about yourself?
It all started with a Christmas present - an electronic
experiment kit. I was about 13 years old and from that time
on I spent most of my
pocket money for electronic components. It was the time when “The
Beatles” fever broke out in Germany and my interest
quickly focused on
During my time at the university I got a side job as a repairman
in a music shop. This was the time when I received my “real” education
When and where did you start Palmer?
It was in the summer of 1978 when I started a small production
of tube amplifiers.
January 1981 is when Palmer officially became my brand name.
(In Germany, bureaucracy is a big lame duck which cannot
Very soon after we had started the amplifier production
that only by making our own transformers could I get complete
control over the sound.
It was a small step from tube transformers to quality microphone
line transformers. The growing public address (P.A.) market
in the 80’s
created a demand for audio tools we called the DI boxes,
splitters, isolation boxes and so forth. I turned my focus
these products. In 1989 the amplifier production was ceased.
After about 500 amps, the decreasing quality of available
tubes at the time had crucified me.
What are you doing now?
I am in charge of the Palmer Products division of Adam Hall
Today many Palmer products are based on the transformers
which we produce
here in Germany. Additionally, to stay in touch with the
developments in live sound and recording studio technique,
I give classes
in electronics at an audio engineering school.
PDI-03 RELATED QUESTIONS:
What year did you release the original 03?
I built my first simulator in the seventies to use in my
workshop. We used a special unit which we called the “silent
which eliminated the noise in the air when testing our amps
I did not like the load boxes made with resistors. As a
repairman I had
seen a good number of amps killed by the use of an Altair
(at that time a very popular item). Based on the literature
Thiele/Small I had built a circuit which simulated the impedance
of a guitar speaker in a box. This became the load part of
speaker. To have an acoustic control I included a filter
to simulate the
frequency response of the speaker as well and fed the signal
into my old
stereo. Everybody was happy with it, especially our neighbors.
Home recording had become popular. It was only logical to
convert our in-house "silent speaker" into a commercial
The term "silent speaker" was altered to Speaker
During the Musikmesse 1989 in Frankfurt (this is the equivalent
show to the Winter NAMM in Anaheim) the Speaker Simulator
displayed at a trade show. It was also in our product flyer
How many versions were there? What were the major differences?
The original unit was only labeled “Speaker Simulator”.
Inside is one
main pc-board. Potentiometers, sockets and switches are connected
leads to that board. The resistive part of the load comprises
aluminum cased resistors on a bent aluminum sheet metal.
resistors were rated at 150 watts, the unit got really hot.
could be varied with two switches, flat or deep for the low
mellow, normal and bright for the treble end.
One of the first modifications was to replace the heat sink
aluminum extrusion and to add one more resistor to make the
In 1990 all Palmer products got stock numbers. Since we
had a passive
DI box (PDI-01), an active one (PDI-02), and the Speaker
Simulator was a
kind of Direct Box it became PDI-03. After October 1990 all
issued with a serial number. In January 1994 the “battleship
housing was replaced with a metallic anthracite color and
the silk screen
printing was green. Also the metal knobs, a surplus from
production, were replaced with plastic types.
The last PDI-03 was made in July 1996.
The other electric modifications were marginal. For easier
production the potentiometers and sockets were put on auxiliary
p-c boards. The switch for the low end response received
position which is between Flat and Deep. The 1K log taper
potentiometers were replaced with 10K linear types and
a 1K resistor,
because of the large tolerances. The potting boxes of some
have changed due to availability.
But I never ever have changed the filter circuit. It is
filter design that was used for my workshop model. Since
we used 5% capacitors and 1% resistors in the filter network.
We've read reviews that say the PDI-09 and PDI-03 have the
circuit. Is that true?
Yes. The PDI-09 uses the same highcut-filter circuit as
the PDI-03. The
PDI-09 is nothing else than a PDI-03 without the load part
signal splitter feature. The PDI-03 has an extra (switchable)
Oh! In the mid 90’s the “Normal” position
was made a bit softer, but
this is the only sound modification the PDI-09 has ever gotten.
What is the difference between the PDI-03 and PGA-04 filter
The PGA-04 was my answer to customers asking for more versatility.
Though you may read many different comments, the heart of
is the original filter circuit with the two switches replaced
two potentiometers for a continuous control between the extreme
positions of the switches.
The original 03 is surrounded by
almost legendary status. We found
one on E-Bay today that was selling for $1200. If you can,
the mystique surrounding the PDI-03.
I can only guess, but the fact that the PDI-03 was used
and praised by some
very popular artists and producers, the unavailability in
for the normal customer, and that Palmer is a small boutique-like
company without publicity could be the reason.
We know you are excited about the re-issue of the PDI-03.
What prompted you to re-issue it?
There existed a patent for a unit that claimed to do the
same job as a PDI-03. Though I never had seen the unit before,
this guy threatened me with legal action and defamed me as
a thief having stolen his ideas.
Ridiculous. Palmer did not infringe upon anyone else's patent--and
now the patent has expired. It looks that there is still
a demand for a more authentic speaker sound even after all
the modeling amps with digital speaker simulation. E-Bay
is the confirmation. Shall I wait until I see a knock-off
copy from China?
How close to which original is it?
It will be a re-issue of the early 90’s model with
the "battleship grey" housing, metal knobs, and
of course the improved heat sink.
Is it the exact same technology as the older 03 or is it
a new design?
How much is it going to cost?
Fortunately we kept all the production paperwork and test
hopefully the fact that the new housing is laser cut instead
punched will not influence the sound.
The price will be the same as for the PGA-04.
When do you expect to have it ready for release? What are
some of the
problems you have had with trying to get it back in production?
Since we had all the production documents I was very optimistic
the production very fast. But it turns out that we have had
difficulties in getting our components. Especially the switches
used to be “off the shelf components”. We are
now having to get them custom
made for us.
Martin, thanks so much for taking this time out of your
busy schedule for this
interview. Are there any closing comments you would like
Please allow one (very last) comment about the PGA-04 vs.
The PDI-03 was a very simple to use piece of equipment. You
wrong. With the more versatile PGA-04 you can produce some
sounds. But this does not mean that -as some people say-
the PGA-04 is
In case someone is telling you that, please charge him with
twice the price
for his PDI-03.
Martin. Martin. Martin. You know we can't do that! (Can
Thanks so much for a great interview!