Revolutions Per Minute

    The Big Move, Part Three

    Issue 133

    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.

    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!

     

    The full Tektronix setup on the original trolley, with various modules.

    The full Tektronix setup on the original trolley, with various modules.

     

    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.

    Plug-in modules for the Tektronix mainframe.

    Plug-in modules for the Tektronix mainframe.

     

    We actually have a collection of oscilloscopes, some of them even solid-state and portable, but the Tektronix 545 still sees plenty of use.

    Another plug-in module and a Tektronix vacuum tube signal generator.

    Another plug-in module and a Tektronix vacuum tube signal generator.

     

    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.

    The Tektronix mainframe in front of the Hardinge HLV late, in the machine shop, assisting with mechanical measurements.

     

    A collection of other instruments on the lab bench, including the Hewlett-Packard 3580A spectrum analyzer.

    A collection of other instruments on the lab bench, including the Hewlett-Packard 3580A spectrum analyzer.

     

    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 Thurlby Thandar function generator and an Agnew Analog current-regulated power supply unit on one of the equipment racks.

    A Thurlby Thandar function generator and an Agnew Analog current-regulated power supply unit on one of the equipment racks.

     

    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 3 kW variable transformer in the lab.

    A 3 kW variable transformer in the lab.

     

    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.

     

    The side of the Soviet military L3-3 tube tester.

    The side of the Soviet military L3-3 tube tester.

     

    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).

     

    The L3-3 (“Kalibr”) was what the Soviet military considered a “portable” tube tester for field use. The controls are all labeled in Cyrillic and the tube tester itself is heavy enough to induce spine injuries even without having to run through the snow with it in the midst of artillery fire, while leafing through the 1,000 page unbound instrument manual in a desperate attempt to figure out if that radar tube really was out of spec…

    The L3-3 (“Kalibr”) was what the Soviet military considered a “portable” tube tester for field use. The controls are all labeled in Cyrillic and the tube tester itself is heavy enough to induce spine injuries even without having to run through the snow with it in the midst of artillery fire, while leafing through the 1,000 page unbound instrument manual in a desperate attempt to figure out if that radar tube really was out of spec…

     

    The Funke W20 tube tester. Max Funke walked his family through the woods to West Germany, with his whole factory containered and shipped on in a train. The German Democratic Republic authorities stopped the train and confiscated all his equipment, but he was able to build it all up again from scratch.

    The Funke W20 tube tester. Max Funke walked his family through the woods to West Germany, with his whole factory containered and shipped on in a train. The German Democratic Republic authorities stopped the train and confiscated all his equipment, but he was able to build it all up again from scratch.

     

    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).

    An instrument for measuring the dwell angle of the contact breaker points in mechanical automotive ignition systems.

    An instrument for measuring the dwell angle of the contact breaker points in mechanical automotive ignition systems.

     

    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.

    One of the soldering stations on a cluttered bench.

    One of the soldering stations on a cluttered bench.

     

    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.

    Our FW Bell Model 610 Gaussmeter. The mirror strip on the meter allows the operator to eliminate parallax error, for extremely accurate readings.

    Our FW Bell Model 610 Gaussmeter. The mirror strip on the meter allows the operator to eliminate parallax error, for extremely accurate readings.

     

    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.

    A stereoscopic microscope.

    A stereoscopic microscope.

     

    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.

    One of the battery banks, from which clean and stable AC power is generated, protecting the laboratory installation from the neighbor’s switch-mode power supplies, the poor-quality power supplied by the grid, and black-outs in the middle of critical work.

    One of the battery banks, from which clean and stable AC power is generated, protecting the laboratory installation from the neighbor’s switch-mode power supplies, the poor-quality power supplied by the grid, and black-outs in the middle of critical work.

     

    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.

    The two Telefunken M15A tape machines, as bare frames, along with the crane that was used to move them around. Each bare frame weighs in at about 160 lbs. The original Telefunken catalog showed a 100-lb. suitcase-style carrying case, to turn your M15A into a 260 lb. “portable” tape machine for field recordings, with a single carrying handle on top, implying it would be carried with one hand (“recording engineer wanted, must be able to lift 260 lbs. single-handed”)!

    The two Telefunken M15A tape machines, as bare frames, along with the crane that was used to move them around. Each bare frame weighs in at about 160 lbs. The original Telefunken catalog showed a 100-lb. suitcase-style carrying case, to turn your M15A into a 260 lb. “portable” tape machine for field recordings, with a single carrying handle on top, implying it would be carried with one hand (“recording engineer wanted, must be able to lift 260 lbs. single-handed”)!

     

    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.

    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.

    A great-sounding John Broadwood & Sons grand piano, made in 1904.

    A great-sounding John Broadwood & Sons grand piano, made in 1904.

     

    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.

    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.

    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 Manley Stereo Variable Mu vacuum tube mastering compressor/limiter.

    The Manley Stereo Variable Mu vacuum tube mastering compressor/limiter.

     

    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.

    3 comments on “The Big Move, Part Three”

    1. Wow, this is an Aladdin’s cave ! You should get a couple of M10s to go with the M15As so that you have the option of a full vacuum tube signal path. And then a complement of V72, V76, V69 etc. to complete the chain. And don’t forget the M251 and U47. My dream Telefunken setup.
      Those vacuum tube Tek scopes are wonders of the ancient world. The noise and bandwidth performance is state of the art, using a balanced differential front end with zero feedback to give 10 MHz of bandwidth.

      1. Adrian and Frank, thank you for your kind words! I am working on the full vacuum tube signal path, but in a different way: Instead of M10’s, I’ll keep the Ma15A transports and install tube electronics of my own design on these!

        All the tube-era Tek plug-in modules are very impressive indeed!

    Leave a Reply

    Also From This Issue

    Open Reel Tape: The Ultimate Analog Source? Part Two

    In the previous article in this series (Issue 132), we…

    A Hard Rain’s Gonna Fall

    Chuck Leavell: The Tree Man, A World-Class Keyboard Player

    Rock and roll documentaries have become fairly predictable. Over the…

    Lend Me Your Ears

    A circa late 19th or early 20th century proto-jukebox. Listeners…
    Subscribe to Copper Magazine and never miss an issue.

    Stop by for a tour:
    Mon-Fri, 8:30am-5pm MST

    4865 Sterling Dr.
    Boulder, CO 80301
    1-800-PSAUDIO

    Join the hi-fi family

    Stop by for a tour:
    4865 Sterling Dr.
    Boulder, CO 80301

    Join the hi-fi family

    linkedin facebook pinterest youtube rss twitter instagram facebook-blank rss-blank linkedin-blank pinterest youtube twitter instagram