The Neumann U 87 is a type of microphones that just about wants no introduction. Stroll into main recording studios anyplace on the earth and there’s a excellent likelihood you’ll discover one, typically a number of.
Launched in 1967, the U 87 has remained in manufacturing for practically 60 years and has develop into one of the recognisable studio microphones ever made.
I’ve seen U 87s from the late Nineteen Sixties and Nineteen Seventies nonetheless getting used each day. They may have a couple of scratches or dents from a lifetime of periods however they proceed to make data.
After visiting Neumann’s manufacturing unit and watching a U 87 being comprised of the start, it grew to become a lot simpler to grasp why.
And after I say “from the start,” I actually do imply the start.
A U 87 begins life as a big piece of brass.
From a Stable Piece of Brass
One of many first issues that shocked me on the Neumann manufacturing unit was seeing cabinets filled with brass rods and tubes of various diameters.
These are the uncooked supplies from which the mechanical elements of Neumann microphones are made.
The physique of the U 87 doesn’t arrive on the manufacturing unit as a completed shell able to be assembled. Neumann begins with brass and machines the person elements themselves.
A bit of the suitable brass rod is lower and brought to a milling machine the place an unlimited quantity of fabric is eliminated till what stays turns into the microphone physique.
Holding the uncooked piece of brass after which holding the completed half is kind of extraordinary. The unique materials is extremely heavy whereas the completed physique weighs a fraction of that.
This isn’t merely about creating the recognisable form of a U 87 both.
The machining must be terribly exact.
The basket ring, openings for the polar-pattern selector and pad and the varied grooves and mounting factors are all machined by a number of phases. Some dimensions are managed all the way down to hundredths of a millimetre.
Watching fashionable computer-controlled machines doing this additionally raised an apparent query:
How on earth did Neumann manufacture these microphones 50 or 60 years in the past?
At this time there are huge CNC machines doing work with unimaginable repeatability. Earlier generations of Neumann engineers needed to obtain comparable outcomes utilizing way more handbook manufacturing methods.
That historical past of precision manufacturing is constructed into the microphone.
Why the U 87 Physique Lasts for A long time
After machining, the brass elements obtain their floor therapy.
What we see on a completed U 87 isn’t naked brass. Neumann makes use of a number of floor layers designed not merely to look good however to guard the microphone from corrosion and bodily put on.
That helps clarify one thing I’ve seen numerous instances in studios.
You’ll find U 87s which have been used for 30, 40 or 50 years. They could have marks and dents from real-world studio use however mechanically they continue to be remarkably sturdy.
Neumann’s strategy to finishes can also be way more concerned than merely spraying some paint onto a microphone.
Coatings are examined for long-term sturdiness, environmental situations and bodily put on. Neumann’s intention isn’t to create a end that survives a few years. They’re considering by way of microphones which will nonetheless be working a number of a long time from now.
Constructing the Well-known U 87 Head Basket
The pinnacle basket is one other fascinating piece of engineering.
It begins as sheets of steel mesh that are lower into the suitable sizes.
However the U 87 grille isn’t comprised of a single piece of mesh.
It makes use of three totally different layers.
There’s a effective layer, a rough layer and a medium layer. Every has a objective.
Collectively they supply mechanical energy and safety for the capsule whereas one layer additionally contributes a level of pop filtering.
The three meshes should even be organized accurately so the visible sample of the grille stays constant from microphone to microphone.
The layers are aligned and welded collectively so they can’t transfer relative to one another. They’re then positioned right into a forming machine which stamps the flat mesh into the recognisable curved form of the U 87 basket.
Apparently, this a part of the method combines fashionable pc management with equipment relationship again a long time. One of many machines we noticed was from 1979 and continues to be getting used as a part of the manufacturing course of.
Every half of the basket is shaped individually.
The 2 halves are then joined with the beforehand machined basket ring and a T-shaped brass profile earlier than being soldered collectively.
This isn’t merely structural.
The basket additionally varieties a part of the microphone’s Faraday cage, serving to defend the extraordinarily delicate electronics inside from interference. The solder joints due to this fact have to be mechanically sturdy and electrically dependable.
The Electronics Are Protected Too
The protecting philosophy continues contained in the microphone.
The digital amplifier assemblies utilized in Neumann’s large-diaphragm microphones obtain protecting coatings designed to assist keep the extraordinarily excessive impedance situations required inside a condenser microphone.
Moisture is vital right here.
A condenser microphone is used straight in entrance of singers, audio system and devices and human breath accommodates moisture. Humid air is extra conductive than dry air and that may probably have an effect on a really excessive impedance circuit.
So even one thing that seems so simple as a protecting clear coating turns into an engineering drawback.
Neumann described altering considered one of these coating programs as probably requiring months of testing as a result of it has to proceed doing its job for many years.
Making the Coronary heart of the U 87: The Capsule
Then we get to maybe probably the most fascinating a part of all the course of.
The capsule.
That is the place the extraordinary stage of precision concerned in making a U 87 turns into much more obvious.
The U 87 makes use of a large-diaphragm condenser capsule, with a diaphragm roughly 25.4 mm, or one inch, in diameter.
As soon as once more, its building begins with brass.
A stable brass rod is lower into slices and people items are machined into what’s going to finally develop into the again electrodes of the capsule.
Quite a few holes are exactly machined into the again electrode.
Some cross all over whereas others terminate inside the fabric. These cavities kind a part of the acoustic system behind the diaphragm.
A central opening additionally receives an insulating materials as a result of the capsule is centre terminated. The centre screw is steel and conductive so it should stay electrically remoted from the again electrode.
Every thing has to stay safe and secure for many years.
Creating the Microscopic Capsule Hole
At this stage the floor of the again electrode continues to be primarily flat.
That isn’t sufficient to make a condenser capsule.
A condenser requires two conductive surfaces separated by an especially small distance. Neumann due to this fact performs one other terribly exact machining operation to create the tiny step that establishes the hole between the diaphragm and again electrode.
This floor must be exceptionally flat.
Any variation in that distance modifications {the electrical} and acoustic behaviour of the capsule.
Neumann summed up the problem superbly throughout our tour:
Making one microphone that sounds good is comparatively straightforward. Making 100 microphones that each one sound the identical is way more durable.
That consistency is actually the central theme of all the manufacturing course of.
This isn’t merely about making one distinctive microphone.
It’s about repeatedly manufacturing extraordinarily delicate elements to extremely tight tolerances after which producing U 87 after U 87 that behaves the best way it ought to.
Each tenth again electrode is checked utilizing a laser scanner to measure flatness and the precision of that microscopic step. Neumann appears to be like not just for particular person failures but in addition for developments.
If measurements start slowly shifting away from the required specification, the machining instruments could be changed or recalibrated earlier than the issue turns into important.
We’re speaking about micrometre-level precision.
Inside Neumann’s Clear Room
As soon as the mechanical elements of the capsule are full, manufacturing strikes right into a clear room.
There’s a excellent cause for this.
The gap between the diaphragm and the again electrode is so small {that a} single particle of mud can alter the best way the diaphragm behaves.
As Stefan defined throughout our go to, a grain of mud may successfully trigger the membrane to behave like a tent round that particle moderately than shifting freely as meant.
Everybody coming into due to this fact wears protecting clothes, shoe coverings and gear designed to minimise static electrical energy and contamination.
That is the place the diaphragm is made.
A Six-Micron Gold-Sputtered Diaphragm
The diaphragm begins as an extremely skinny plastic movie.
The movie is mounted between steel rings which create what Neumann calls the mom membrane.
At this stage the plastic itself isn’t conductive so it can not but kind a part of a capacitor.
Neumann makes use of a course of referred to as sputtering to use an especially skinny layer of gold to at least one facet of the membrane.
The membrane is barely round six microns thick.
Holding considered one of these gold-sputtered membranes was a type of moments the place you realise simply how delicate the center of a condenser microphone actually is.
The diaphragm is extremely fragile but as soon as assembled into the microphone it might probably stay purposeful for a lot of a long time.
Assembling the Capsule by Hand
This a part of the method continues to be finished by hand.
The gold-coated diaphragm is fastidiously positioned over the again electrode.
The central termination screw is fitted and a hoop is positioned to carry the diaphragm in place.
The screws across the perimeter are tightened in a deliberate sequence, shifting round reverse sides of the capsule to supply managed and even stress.
Watching it jogged my memory of tuning a snare drum though clearly on a very totally different scale of precision.
After meeting, the capacitance is measured instantly.
The surplus membrane materials is then fastidiously eliminated and the measurement is repeated to make sure the capsule nonetheless behaves precisely as anticipated.
However a U 87 doesn’t comprise simply considered one of these assemblies.
It’s a dual-diaphragm microphone.
So Neumann wants two capsule halves.
Matching the Entrance and Again of the Capsule
The 2 capsule halves are measured and matched in response to their electrical and acoustic properties.
That is vital as a result of the U 87 gives cardioid, omnidirectional and figure-of-eight polar patterns by combining the behaviour of the entrance and rear sides of the capsule.
If the 2 sides don’t behave persistently, neither will the polar patterns.
The matching isn’t merely tutorial. It straight impacts whether or not the microphone behaves accurately when the sample selector is modified.
As soon as two appropriate halves are chosen, they’re joined along with a exactly made steel spacer sustaining the proper relationship between them.
Solely now do we’ve got the whole capsule that may develop into the acoustic coronary heart of the microphone.
Remaining U 87 Meeting
The finished capsule strikes to the microphone meeting space.
Every workstation is organized for particular microphone fashions. The technicians themselves additionally specialize in specific fashions moderately than each particular person constructing each microphone Neumann produces.
For a microphone such because the U 87 there are devoted meeting stations.
Different microphones could be significantly extra specialised, with some fashions requiring technicians who’ve spent years studying their specific building strategies.
On the U 87 workstation, the capsule is fitted into its holder and suspension system.
A protecting aspect sits above the capsule to assist forestall harm if the microphone receives a heavy influence and the capsule strikes towards the within of the grille.
The capsule wiring is linked and sealed.
The amplifier and digital meeting is put in into the principle body earlier than the well-known U 87 physique slides over it and the underside part is hooked up.
At this level, in spite of everything these particular person manufacturing operations, it lastly appears to be like just like the microphone all of us recognise.
However it nonetheless isn’t prepared to depart Neumann.
Each U 87 Has to Cross the Human Check
The testing course of begins with one thing surprisingly easy.
An individual listens to it.
The microphone is powered and spoken into so the technician can hear whether or not it behaves usually.
Additionally they intentionally expose the microphone to moisture from human breath.
Why?
As a result of that creates real-world working situations.
The technician listens for modifications in noise or behaviour as humidity reaches the capsule.
Neumann even has a unprecedented gadget for listening to microphone self-noise.
The microphone is lowered into an enormous double-walled steel tube crammed with sand and acoustically remoted from its environment. The sign is then amplified enormously so a technician can pay attention carefully to the character of the microphone’s inherent noise.
They’re not simply asking whether or not the microphone produces noise.
They’re listening to what sort of noise it produces.
Completely different behaviours can point out issues with the capsule or electronics.
Then the Robots Take Over
After passing the human analysis, the microphone strikes into automated acoustic testing.
Neumann makes use of an anechoic measurement atmosphere and a robotic system able to putting every microphone in precisely the identical place repeatedly.
Earlier than measuring the U 87, the system calibrates itself utilizing a measurement microphone.
It then selects the suitable mechanical arm for the U 87, masses the related tolerances and locations the microphone above the take a look at loudspeaker with millimetre precision.
The system measures the microphone in a number of configurations.
Sensitivity is examined.
Frequency response is examined.
The microphone is rotated to measure its response from quite a few angles.
Cardioid, omni and figure-of-eight operation are checked.
The pad is checked.
The high-pass filter is checked.
Polarity is checked.
Directivity is checked.
Solely when all of these measurements fall inside specification does the microphone obtain a:
PASS.
Neumann Retains the Measurements
One element I discovered notably attention-grabbing is that the measurement knowledge from each microphone is saved.
That provides Neumann an unlimited quantity of details about manufacturing consistency.
If measurements start displaying a development over time, engineers can determine it earlier than it turns into a severe manufacturing challenge.
There may be one other vital benefit.
If that microphone returns to Neumann for service years later, they’ll refer again to its unique measurements.
They understand how that individual microphone behaved when it left the manufacturing unit.
Neumann even retains historic acoustic measurements from microphones constructed many a long time in the past. A few of these unique measurements had been actually drawn onto paper by mechanical plotters.
That permits engineers to check historic capsules with new manufacturing capsules and examine whether or not the unique acoustic behaviour has been maintained.
This maybe will get to the center of the entire course of.
Neumann isn’t counting on reminiscence or mythology relating to how these microphones ought to carry out.
They’re measuring them, documenting them and evaluating them over a long time.
The Microphone Will get a Birthday
As soon as testing is full, the ultimate documentation is ready.
The microphone certificates receives the mannequin, serial data and manufacturing date, one thing Neumann moderately splendidly refers to because the microphone’s date of start.
The microphone receives a ultimate visible inspection and is positioned into the acquainted reddish-brown picket Neumann field.
Even these bins are a part of Neumann’s manufacturing philosophy and are made in southern Germany.
Relying on the package deal, the microphone might also be provided with its elastic suspension.
Then, lastly, the microphone is able to go away the manufacturing unit.
Why These Microphones Final
Strolling by this whole course of modified the best way I take into consideration the U 87.
We have a tendency to speak about microphones totally by way of sound.
Does it sound heat?
Is it vibrant?
How does it examine with a classic microphone?
These are worthwhile conversations, however seeing how the microphone is definitely manufactured offers you a very totally different perspective.
The outstanding factor isn’t merely that Neumann could make one nice microphone.
It’s the sheer period of time, precision and a spotlight required to make the identical microphone persistently, time and again.
They start with uncooked brass.
They machine the physique to extraordinarily tight tolerances.
They kind and solder a three-layer grille.
They manufacture the capsule electrodes from scratch.
They machine a microscopic diaphragm hole.
They create a six-micron gold-coated membrane.
They assemble the capsule by hand.
They measure it.
They match the 2 capsule halves.
They assemble the microphone.
They take a look at it with individuals.
They take a look at it once more utilizing precision measurement gear.
Then they archive its particular person measurements in order that they know precisely the way it carried out when it left the manufacturing unit.
None of this feels
rushed.
Each stage is designed round consistency, sturdiness and the expectation that this microphone should still be working a long time from now.
After seeing all of this, one thing I’ve seen all through my profession makes way more sense.
I’ve walked into studios everywhere in the world and located Neumann microphones which have been working for 30, 40, 50 and even 60 years.
Now I perceive extra clearly why.
The longevity isn’t an accident.
It’s constructed into the microphone from the very first piece of brass.
Have a marvellous time recording and mixing!
