The Xaudia Blog

17-09-2013

Something old and something new – STC Coles 4038 and 4050

A good customer brought in his Coles 4050 stereo microphone for show-and-tell, which gave us a good opportunity to compare and contrast with some of the STC-Coles mics from the past.

STC4033, 4038 and Coles 4050 microphones

On the of the photo left is the imposing and impressive STC 4033, which contains both a ribbon mic and a ‘ball & biscuit’ dynamic element. These combine to give a cardioid pattern, which was difficult to achieve at the time.

In the middle sits a 4038, which is perhaps the classic British broadcast ribbon – designed by and made for the BBC. This one was made by STC, and they are still made to the same design by Coles Electroacoustics. The soap-dish styling is dictated by the large horseshoe magnet inside.

The 4050 stereo mic is on the right, and looks very different again. It is a more modern styling but form still follows function, and strong neodynium magnets are used not only for the ribbon motor, but also to fix the mics to the stand mount. This allows free rotation and makes setting up for Blumlein pairs very quick and simple.

Frequency sweeps of 4050 (top, red & yellow) and 4038 (bottom red)

We ran a frequency plot of both halves of the 4050, and of the 4038.* Both mics sound very good, and although the old 4038 had a smoother top end roll off, the 4050 had an extended about +6 dB higher output and an extended frequency response. We were also very impressed with how well matched the two 4050 ribbons were – less than ±0.5dB across the range, and mostly much better than that.

The 4038 is prettier though!

* Taken at 30 cm distance. Please note that some of the bumps are due to our test chamber – there are issues with calibration when comparing a figure 8 ribbon with an omnidirection reference mic.

Thanks to John Gooding

10-09-2013

Fi-Cord FC1200A tube microphone

This nice Fi-Cord 1200A tube microphone arrived without a power supply… so we built a new one!

The problem with these mics is that they are filled with resin, and it is almost impossible to get inside them. The mic has a Nuvista tube (like the AKG C28c) somewhere deep inside. Thankfully this one was working well so it just needed a new cable and an Xaudia custom power supply….

These mics were designed and built by Calrec, so it should be no surprise that they sound really good! There is a bit more information about Calrec Fi-Cord mics at Saturn Sound.

Thanks to Santiago Ramos

07-09-2013

BBC-Marconi Ribbon Microphone Type B

Our microphone of the month for September is this a rare and lovely BBC-Marconi ‘type B’ ribbon microphone. The type B is closely related to the ‘A’ series of mics (AX, AXB and AXBT) which were made from around 1935 onwards. The model B was made from 1937 onwards and used the same motor assembly, but with a smaller (yet still massive) magnet and without the ribbon tension adjustment facility.

BBC Marconi type B, side view

The smaller magnet format allowed the mic to be packaged into a smaller cylindrical body, and these were apparently were often used for outside broadcast, attached to the chest of the broadcaster! One would have to be pretty strong to carry that around all day.

Although this is widely know as the model ‘B’, the nameplate calls it 8559A.

BBC Marconi type B badge

As well as the outer grill, there are two extra windshields inside the mic, which would have protected the ribbon from wind blasts and dirt. These windshields did their job well – in this example, the ribbon is unbroken, but this has oxidised and stiffened over the years and will need to be replaced.

BBC Marconi type B ribbon motor

The magnet and motor assembly are held in place with foam rubber, which has mostly survived the years. The output transformer is hidden behind the magnet. This had a break in the secondary winding, but luckily I was able to unwind it by a single turn and bring the mic back to life.

BBC Marconi type B, transformer

At the rear of the mic, connection to the outside world is made by three screw terminals, and square bulge at the bottom shows the location of the transformer.

BBC-Marconi ribbon mic, rear

Overall, the mic sounds warm and rich, although the metal can gives it a certain ‘boxy’ sound that instantly defines it as a very old microphone!

There is some more info about the BBC-Marconi ribbon mics at the Coutant and Orbem websites.

Thanks to Tom Barwood

05-09-2013

The Americans are coming

Here is a trio of American model R331 ribbon mics…

American R331 microphones

These rather pretty looking mics made a brief appearance in Back to The Future (at the end, where Marty sings Johnny B Goode….)

Is this the DeLorean of microphones? No.

The mic can be set to either low (50 ohms), medium (250 ohms) or high impedance using jumpers and clamps hidden behind the badge. The inside of the mic looks like a bowl of spaghetti where all the wires from the transformer are run out to the panel.

Impedance settings for the R331

The mic also has a block of wood in it! In fact American Microphones made a range of three ribbon mics, and the sister models – the DR330 and DR332, both employed a dynamic capsule as well as the ribbon motor. In the R331, the wooden block fills the space which would otherwise be occupied by a dynamic capsule – a low tech but effective solution to the problem.

The motor is simply made of two magnets screwed and welded to a metal frame, and the ribbon itself is about 2.1 mm wide. This one needed some welding and a new ribbon, but once repaired sounds nicely balanced for a vintage ribbon, with the transformer rolling off some of the bottom end to compensate for the proximity effect.

American R331 ribbon motor assembly

There is a lot more information about the R331, DR330 and DR332 at Coutant.org

Thanks to Myles Davis

20-08-2013

Lustraphone Badges in stock!

I see a lot of Lustraphone VR53 mics around that have lost their original badges – like the ones on the left and right. The glue that was used wasn’t great, and they look rather sad without their original nameplate.

Replacement Lustraphone badge

I am delighted to say that we have just taken delivery of some replacement badges for these that look absolutely fabulous. They have a silver logo on a vintage cream background, just like the originals.

Lustraphone VR53 with new badge!

They of course also fit the Grundig, Pamphonic and Mimco badged versions of the VR53, and also some of the small Lustraphone dynamics too.

Lustraphone dynamic with new badge!

The badges are £5 each plus post from the Xaudia website.

(Thanks to Best Badges for their excellent service!)

12-08-2013

Ervox R58 – French ribbon mic

Today on the bench we have an unusual microphone from France. I have never heard of this brand!

Ervox R58 ribbon mic

The Ervox R58 is a high impedance ribbon microphone designed for public address or home taping to a reel-to-reel recorder. It is made from a two part cast body, perhaps inspired by the RCA Varacoustic, and is nicely finished in hammertone paint. Paint still covers two of the screws, so I can see that I am the first person to look inside this one, which is always a nice feeling, like unwrapping a present!

Ervox R58, rear

Inside the mic everything looks nice and clean. The motor is built around a sturdy block of clear plastic with a large horseshoe magnet to the rear, and the ribbon itself is a piston-style design similar to those found in B&O and Altec microphones.

Inside the Ervox R58

Unfortunately the transformer is not working properly – the inductance measures only 14 microhenries, which for an (estimated) 0.2 ohm ribbon would make a HPF filter at around 2KHz… I’m sure it can’t have been designed like that, so one suspects either insulation breakdown and a short, or the laminations have deteriorated with age and lost some permeability.

Ervox ribbon motor assembly

I’m not sure if it is worth the effort of re-winding this one, particularly if the lams are below spec. Luckily we can make a new low impedance tranny for it and bring it back to life.

The previous owner kindly included this scan of a wiring diagram for the mic.

09-08-2013

Beebs to Belgium!

We have just shipped this rather lovely set of Reslo microphones to Thomas at Le Lupanar Studios in Belgium. He will be recording a brass section with two of our ‘Beeb’ Reslos, and a pair of upgraded cardioid Reslo CR mics on goosenecks.

His studio is still under construction but Thomas has been making a photo diary of the project – from the pictures so far it will be an amazing facility in a great location! How’s this for soundproofing…

Good luck with the building, and we will watch with interest as it all comes together.
🙂

08-08-2013

Reslo Beebs in Organ Action

Organist Andy Wright used a pair of our Xaudia Reslo ‘Beeb’ ribbon microphones to record his organ playing at St Peter and St Paul Church, Kimpton, Hertfordshire.

Reslos at St Peter and St Paul Church, Kimpton

He kindly sent in this brilliant photo, and an .mp3 file too so that we can hear how it sounds!

Organ recording with Beeb Reslos – Andy Wright.

(Or download the file)

The recording was made with the mics plugged straight into a Tascam DR100 mk 2 and recorded in wav mode, then compressed to mp3 in Soundforge.

In the eighties and early nineties Hyperion Records used the organ to record classical music, including string quartets, piano solo and the Kings Consort doing The Four Seasons. Eventually Luton Airport, about 8 miles away, got too busy!

The Reslo RB mics are perhaps most famous for being used by the Beatles in their Cavern Club days. As a young photographer, Andy was assigned to one of their early gigs, and here are some of those photos at the Daily Mail website.

One of Andy’s photos of the Beatles

You can see more of Andy’s photos at his website.

07-08-2013

Stereo guitar switching box

Carrying on from my previous post….

Matt from Bobby and Jemima, had one of our stereo pickups fitted to his guitar. For stage use, we made him one of these….

3 channel guitar switch box

It’s a very simple custom 3 channel foot-switch box, which lets him control each of the bass, treble and rhythm channels separately. I was pleased with how it came out. Hammertone paint always gives things a 1950s industrial look.

The battery just lights the three LEDs, and should last for ages, so long as the cables are unplugged when not in use.

06-08-2013

Pickup fitting with Bobby and Jemima

I recently installed one of our hexaphonic pickup systems into a a guitar for Matt Shaw, who is one half of Bobby and Jemima.

Bobby and Jemima… AKA Charlese and Matt (not sure who is who!)

Matt provides a large chunk of the music for the act, playing guitar and drums – often at the same time – and he wanted to be able to send bass runs on the lower strings to a bass amp whilst simultaneously playing the melody and lead from the top strings out through a guitar amp. No problem at all!

I fitted a hexapup to the bridge position, wired out to a pair of output jacks, and an additional toggle switch gave the option of sending the G-string to either the bass or treble output. And we put one of our new P90 pickups in the neck position, with its own output for a third amplifier. Now Matt can make a lot of noise with one guitar!

Many thanks to Karen Duckworth who hung out with us for the afternoon and took these marvellous photos.