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.
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.
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.
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!
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.
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 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.
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:
