In Part One and Part Two, J.I. Agnew wrote about the difficulties of moving an entire recording and mastering facility, complete with machine shop, grand piano, literal tons of equipment and other items. The story continues here.
Putting the electronics workshop into place in our new facility was certainly much more of a chilled out experience, compared to moving the machine shop. (The joys of transporting impossibly heavy machines and fitting them inside a building they did not actually fit in were described in graphic detail in Part One and Part Two, Issue 131 and Issue 132.)
Tektronix 545B vacuum tube mainframe oscilloscope.
Some people consider the tube-era Tektronix mainframe oscilloscopes to be overly bulky and excessively heavy. But, once you get accustomed to lifting 2500 lb. chunks of cast iron, using cranes and forklift trucks, our Tektronix Model 545, complete with a range of modules and accessories, appears very reasonably dimensioned! I mean, it even comes with a trolley on casters! It can be wheeled around where needed by a single person, unassisted, without subsequently requiring physiotherapy or psychotherapy!
It contains 50-something vacuum tubes, voltages reaching 10 kilovolts, and its fan bearing (yes, it needs a cooling fan) requires occasional lubrication with a light spindle oil. No big deal. It’s not rocket science. Although I guess it must have been a common sight at NASA back in the day.
We actually have a collection of oscilloscopes, some of them even solid-state and portable, but the Tektronix 545 still sees plenty of use.
It has a very sharp display and with the various modules available, it is perfect for audio work. With a suitable electronic indicator, it can also be used for high-accuracy mechanical measurements.
The Tektronix mainframe in front of the Hardinge HLV late, in the machine shop, assisting with mechanical measurements.
Another vintage instrument that sees frequent use is the Hewlett-Packard Model 3580ASpectrum Analyzer. This is smaller, almost too small, about the size of a common CRT oscilloscope. It assists with frequency response, distortion and noise measurements in audio equipment, while it can also be used for various other applications, such as plotting impedance versus frequency for transducers and to conduct vibration analysis when used with a suitable accelerometer.
A number of signal generators live on the bench, to assist with various measurements, both in the audio and RF ranges. Next to these there are a couple of bridge instruments for impedance measurement, and a standard LCR (inductance, capacitance, resistance) bridge.
A collection of power supply units, ranging from 5 volts DC all the way to a Hewlett Packard 5 kV DC supply and several Variacs (variable transformers, used to supply AC of variable voltage) assist with circuit design and prototyping.
We do a lot of work with vacuum tube electronics, so we of course also have several tube testers in the lab (see Adrian Wu’s “To Test or Not to Test – Part Five,” in Issue 130, for more information about tube testers).
Various multimeters are always at hand, along with IR (infrared) and thermocouple thermometers, motor testing equipment and even some vintage measurement instruments to assist with the adjustment of internal combustion engine ignition systems (I am also very much into classic cars).
The obligatory soldering stations are of course also there, along with some high-power vintage soldering irons for when something large needs to be soldered. We also have vacuum de-soldering equipment and a solder-fume extraction system.
In addition to all the aforementioned equipment, which is fairly common in better-equipped electronics workshops (or at least it was in the 1960s), we also have some oddities: elaborate coil winding equipment, to wind inductors, transformers, and various transducers; specialist testing equipment for various types of audio transducers; and since we do a lot of work with transducers containing permanent magnets, an FW Bell Model 610 Gaussmeter with a variety of probes. The Model 610 is an extremely sensitive instrument – it can easily detect the earth’s magnetic field, which can be zeroed out so as not to interfere with the measurements of magnet assemblies.
For our work with tape machines, we have a few tape head demagnetizers, as well as precision spring scales and other specialized tools. With respect to repairing certain types of cutter heads (for cutting records), we have developed a cutter head calibrator setup, which measures several of the important parameters. One of the new features we are planning on adding in the new facility is a pen recorder, to create a reference calibration graph as each head is being measured. A variety of microscopes can be found on the benches, to assist in working with and measuring very small objects, ranging from SMD (surface mount device) components to miniature coils and transducer parts. A few precision scales, of both the electronic and mechanical type, are also often used to weigh critical transducer parts and assemblies.
But the true challenge in establishing laboratory conditions is to ensure that all these instruments will reliably produce repeatable readings. Apart from the internal calibration of each instrument, it is essential to provide stable external conditions. The electronics workshop is therefore maintained at a steady temperature with controlled humidity levels 24/7, year-round. All the equipment is powered from extremely stable, clean and filtered AC power, generated from a battery bank, so the inevitable fluctuations in voltage and frequency of the electrical grid are prevented from influencing the operation of the laboratory instruments.
This setup is similar to what we had been using in the old building, but there the batteries were charged from the grid, providing an autonomy of a few hours of available power in case of grid outages. This was adequate from a technical standpoint, but this time, the plan is to take it a few steps further. The long-term perspective is for us to use solar and wind power to charge the batteries, disconnect from the grid and generate all the energy we consume on-site using environmentally friendly, renewable sources, which are most efficiently implemented without having to connect to a centralized grid. The recording studio equipment is also treated as if they were measurement instruments, used under laboratory conditions. Powered from their own battery bank and maintained at a steady temperature all year round, the studio electronics are expected to deliver a comparable level of repeatability and accuracy as the measurement instruments. Not much of the studio equipment we were using in the old building will make it to the new studio. The new facility is intended to have a more radical, minimalist approach for maximum audio purity. The signal path will be all-tube and the full-range monitor loudspeakers will be powered by new tube amplifiers of my own design. Details will follow soon.
What we will definitely be keeping are the Telefunken M15A tape recorders, which are among the finest tape machines ever made.
Telefunken M15A tape machines, awaiting installation in the new custom studio furniture.Most of the electronics will be built from scratch. A lot of attention is being paid to the acoustic design of the rooms. The performance spaces will be designed to have naturally reverberant acoustics, and the piano room’s acoustics will be designed around the piano, to best augment its sound, as described in previous articles in Issue 129 and Issue 130.
The control room will be following the “non-environment” school of thought and will contain tape machines and a disk mastering lathe which will also be used for direct-to-disk recording.
One of our disk mastering lathes in action.
What will definitely be absent is a mixing console. Most of the recordings will be of the “two microphones straight into a recording device” type, with no equalization, no compression and no processing whatsoever.
Our custom-made Thermionic Culture Green Fat Bustard vacuum tube summing mixer.“Non-environment” rooms are designed as hemi-anechoic chambers. The front wall is reflective, and the loudspeakers are commonly mounted with the baffle flush with the reflective front wall. The wall acts as a baffle extension and sound can only propagate away from that wall, eliminating rear reflections. The ceiling, side walls and rear wall contain wideband absorbers to eliminate reflections from returning to the listening position. The aim is to remove the room environment from the equation (hence the name) and to allow the direct sound of the monitor loudspeakers to reach the listener, unaffected by room reflections. The decay time is extremely low and the result is a system that is mercilessly revealing of all details in a recording. Only by being able to hear a disconcerting amount of detail do you really stand a chance of hearing any flaws and correcting them, before they make their way into the final product. Once you have great room acoustics, it doesn’t take much equipment to produce outstanding recordings. If the electronics are kept simple and the signal paths short, the true value of the “less is more” philosophy can be appreciated. We will most probably keep the tube summing buss, which had been used to make excellent multiple-microphone recordings in our previous studio. This was a Thermionic Culture Green Fat Bustard, handcrafted in England to my specifications, with several modifications I had requested to match my style of working. We may also keep some other bits and pieces of vacuum tube equipment used in mastering, as we are expecting that the studio will also be used by other engineers for more conventional mastering work.
The studio construction is still very much in progress and will most probably take a while under the current circumstances with the pandemic, as the workforce is inevitably limited to ensure we can all maintain social distancing. As such, it will be a while before the completed facility is presented here in Copper, but it will come, eventually. Detailed and exacting though the studio construction may be, this is by far the simplest part of this move! Despite all the excitement, I must say I am not looking forward to another move anytime soon! It most certainly keeps life interesting, perhaps even a bit too interesting. It is through such experiences that I have learned to appreciate boredom, in the very rare occasions I get to encounter this feeling nowadays.
All images courtesy of Agnew Analog Reference Instruments.
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