Electrovoice V2 revisited

These old Elctrovoice ribbon mics look great but sadly the sound rarely lives up to expectations.

I have worked on a few of these over the years and there are several things that let these microphones down - happily they can all be sorted out with a bit of thought.

EV V2 clamp with through-ribbon bolt!

Firstly, and perhaps most annoying are the ribbon clamps. EV used thin plastic clamps to insulate the ribbon from the body of the mic, and the ribbon is secured by a central screw that goes straight through the ribbon. The old EV ribbons are quite thick and were supplied with (even thicker) copper end terminals,  so that they could just be screwed in place. One problem is that tightening the screw twists the ribbon, pulling it into the side walls of the motor. It also does not make very good electrical contact, especially with a new thin aluminium ribbon. And the clamps are flexible too so the ribbon is not held securely.

New ribbon silver clamp

A better solution is to make new stiff metal clamps. These could be made from plated brass but I tend to use solid sterling silver to avoid the need for a plating process. One clamp must still be insulated from the body of the microphone to avoid shorting out the ribbon.

Rusty old magnet.

The next problem is the weak magnetic field. Replacing the old magnet with a new neodynium one can boost the field around five-fold, which gives a corresponding increase in output. With stronger magnets the steel screws can jump into the ribbon gap and wreck a new ribbon, so it is best to swap the screws out to some brass or stainless ones.

EV V2 transformer.

The old transformers are not great and lack bass but that's an easy thing to sort out! And finally the old plugs are getting hard to find so we can put an XLR on the rear.

XLR fitted to EV ribbon mic

Voila! With new clamps, ribbon and magnet we have a healthy signal with plenty of bottom end!

The world's smallest ribbon mic?

Is this the world's smallest ribbon microphone mechanism?

The Beyer M560n(c) has a motor measuring just 33 mm long and 10 mm deep, which fits into the mouthpiece of a headset.

The tiny transformer is mounted at the other end of the microphone. The mic is clearly designed for close speech and the transformer has a very low inductance (35 µH at 1 kHz), which gives a bass roll off to compensate proximity effect.

Despite its small size, it was not much more difficult to repair than some other Beyer mics. Here is the motor with a new ribbon, ready to go again….

If you know of a smaller ribbon motor, then get in touch!

Pimp my microphone!

Here are some upgraded, modified and generally pimped mics that we have put together for customers.

In each case the microphone gets a new ribbon, upgrade transformer and a few other tweaks, along with a shiny new badge.

I will leave the reader to guess the identities of the donor mics. 

:-)

Transformer boxes

Here are our updated transformer boxes, looking smart with a new metal badge and hammertone paint. They come in a rugged metal box with Neutik XLR connectors at each end for easy use.

These little gadgets are perfect for interfacing old 30 and 50 ohm microphones to modern equipment that expects to see 200 to 600 ohm microphones, and can give an increased output of up to around 12 dB, which is welcome for older ribbon mics.

They are available in a range of ratios, and our most popular model is the 50 Ω to 600 Ω box, which is ideal for Melodium 42B, STC 4033, and Western Electric /  Altec 639 'birdcage' microphones.

These can be supplied to order in almost any required ratio to match your microphone. 

Melodium 42B XLR mod

The old Melodium 3 pin plugs are getting very hard to find, and quite expensive when they do show up. This is a pragmatic approach to the problem, and allows an XLR to be connected directly….

The Switchcraft connector could be painted to match the mic, but I don't mind the nickel either.

A mount for an STC 4017 dynamic mic

A customer asked me to make a mount for his STC 4017 dynamic mic without modifying the microphone itself. Often these come with a handle or a threaded stud for mounting, but this one came with nothing at all.

My first thought was to make some kind of ring clamp, but that would require a large diameter brass tube and was starting to look quite expensive and bulky. So I came up with this…

It is simply a folded strip of aluminium screwed to a threaded brass cylinder. The bass of the cylinder is threaded to fit a 5/8" mic stand. The mic slides into a slot in the aluminium and is held by its own ground clamp.

Some shrink sleeve ensures that the signal outputs are not shorted by the new mount.

Voila!

What's inside a Beyerdynamic M260?

This is what happens when one dissects a couple of Beyerdynamic ribbon mics: bodies, grills, motors, transformers, XLR or DIN output connectors. Nothing surprising there….

But what are those grey plastic tubes?

These are in fact acoustic chambers that provide back pressure to the ribbon, changing it from its natural figure-8 pattern towards being hyper-cardioid. It is also critical to the microphone's sound - if you make an M260 without one, it sounds pretty awful.

There is one more important ingredient to the mic, and that is a piece of string. This is stuffed into the chamber to break up internal reflections. Sometimes simple works!

B&O BM3 ribbon mic - Black Viking edition!

The Black Viking is Xaudia's latest take on the B&O BM3. The vikings came from Denmark and invaded our home town of York, so it seems a fitting name for the mic.

This one has new magnets, new ribbon, a 300 ohm output transformer and XLR output connector. Re-finished in a tough black powder-coating, it is ready for a few more decades of action.

More available soon!

MOTM Tannoy MD422 cardioid ribbon mic

Here is Tannoy's cardioid ribbon microphone - the MD422.

Tannoy MD422 ribbon mic, front

Firstly, Tannoy lose a point for the name. 'MD' should surely mean "microphone dynamic" in any sensible society! Perhaps the D stands for "directional"? Who knows, but it puts them at odds with other the Sennheiser MD421, and it is just plain confusing.

Tannoy MD422 ribbon mic, rear

Whatever the D stands for, the mic itself has an industrial look, and this one is finished in a bronze-ish coloured paint. To the best of my knowledge this is the only cardioid ribbon model that Tannoy ever produced, and it uses an acoustic labyrinth to provide the necessary back pressure to the rear of the ribbon. The chamber is the black cylinder in the photo below.

Tannoy MD422 ribbon mic, chamber

Some of the parts were made to a budget, or perhaps a short production run, with thin stamped metal for the base and top cap, along with two layers of off-the-shelf mesh to protect the mic from dirt and wind.

The ribbon assembly and magnets are the same as found in the type 2 Tannoy 'pitchfork' microphone, which would have saved costs by sharing components.

Tannoy MD422 inside, showing ribbon motor

The MD422 was subject of a BBC technical report, which concluded:"..this microphone has nothing to commend it for use in the Television Service". That assessment seems rather harsh, but at the time the Corporation's selection criteria were flat, uncoloured responses and good signal/noise performance.

In the report, the bi-directional BBC-Marconi AXBT was used as a comparison, which was much more expensive, a different pattern, and therefore a tough benchmark. Cardioid (and non-directional) ribbon mics generally use an acoustic chamber on one side of the ribbon to apply pressure, and this damps the ribbon motion, reducing the output compared with its natural bi-directional response.

Drawing of the Tannoy MD422 from BBC technical document.

Unlike my mic, the BBC's example had a yoke mount rather than a fixed base, although there are mounting screw holes in the side of mine.

Despite my irritation with the model number, and the BBCs damning assessment,  I like this microphone very much. It has a gentle warm tone. More importantly, it was an attempt at technical innovation, which is always to be celebrated.

Reslo MR1 manual

Here is a scan of a 'manual' from 1973 for the Reslo MR1 ribbon microphone, which was the successor to the popular RB model.

I say 'manual' - really it is just two sheets of printed A4.

The ultimate guide to ribbon mics - Music Tech mag.

Music Tech magazine have just published the 'ultimate guide' to ribbon mics.

Xaudia got a mention!

Reslo Dynamic microphones

Reslo are of course best known for their ribbon microphones, particularly the RV and RV models, However, it should not be forgotten that over the decades they made many dynamic microphones, and even some condensers too.

Reslo VMC with base station

The earliest Reslo dynamics seem to be the VMC and VMC2, with the initals standing for Velocity Moving Coil. These had a big heavy permanent magnet and a paper diaphragm, and are really rather lo-fi devices. These two models are more or less the same inside, although the VMC was hard-wired, and the VMC2 had a new grill and an output plug.

Reslo VMC2, with output connector.

In the late 1960s Reslo made a range of more modern light hand-held dynamic mics. The UD1 used a Japanese-made capsule which sounds rather good, of comparable quality to the Shure mics of the era. I have seen transformerless 200 ohm models, and also a dual output 30 & 600 ohm version with a transformer in the body to convert the impedance.

Reslo UD1 microphones

The UD1 was apparently used by Bob Dylan at the 1969 Isle of Wight festival!  Here is an advertisement scan from the Reslosound blogspot….

The advertising also mentions a high impedance model, although I haven't come across one yet.

Some of the UD1 mics were hard-wired to the cable, and it was also supplied with a Reslo connector, and later a 3-pin din plug, with different impedance options available through the different pins. They are wired like this, with one side of the capsule and transformer primary wired to the output socket.

In addition to the UD1, there was a short stubby version that used the same components, and would often have been used with a gooseneck adapter. Pictured below is also a smaller dynamic mic for use with a tie clip.

These models appear to have been replaced in the 1970s by the Reslo Superstar range, which were essentially the UD1 with an updated body and grill. The Superstar was supplied with a DIN plug - I have converted this one to XLR.

Reslo Superstar 80 dynamic mic.

SJT, May 2014

Film Industries M5 dynamic microphone

Film Industries Ltd. are perhaps best known for their M8 ribbon microphone, but what about models M1 to M7? Well, here is 14.286 % of the answer: the M5 moving coil microphone.

Film Industries M5 moving coil microphone

This model was likely to be a competitor to the Reslosound VMC, and like the Reslo, the M5 features a paper diaphragm driving a moving coil in a magnetic field. The output is wired to a pair of screw terminals, for easy wiring without the need for a custom connector. It does not have a separate ground connection.

The large black rubber cylinder at the base is supposed to give some vibration damping, although perhaps not enough to make a major difference.

Although a 30 ohm mic, this one at least has a strong output, due to the large strong magnets.

And here's a somewhat wiggly frequency sweep of the mic:

Reslo Beeb Commando!

Here is a custom edition of our popular ‘Beeb’ modified Reslo ribbon mic. This is the first, and so far the only one we have made in these colours.

Like all of our 'Beeb' mics,  this features an upgraded 300 ohm output transformer, new ribbon and XLR socket. This special edition as well as a switchable high pass filter inductor to balance the proximity effect when used close to sources.

The custom camouflage colours makes it suitable for undercover operations, and even better for guitars and drums!