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!
This was Reslo’s attempt at a commentator’s lip microphone, and appears to be cobbled together from spare RB parts. The upper body and head are from an RB, but the head is rotated through 90 degrees and screwed to another chopped-down head. The lower body-stroke-handle is a straight aluminium tube with a switch which terminates in a normal Reslo output socket.
Inside the head is a rotated RB-style motor. The magnets face the speaker, to provide some pop protection for the ribbon at the rear.
Behind the ribbon I found this metal baffle, which should control the pickup pattern and tweak the frequency response. There is also fibre glass and felt wadding for more protection.
Overall it is a strange little mic. The ribbon runs horizontally, which is generally considered a bad plan as, if it sags, it will droop into the metal pole pieces. They must have been a way of producing a lip mic without the expense of re-tooling for a completely new design. I have only ever seen this one, although I know of a customer who owns another.
Dirk at V76 Studios in Hamburg was kind enough to share some sound files of his BM5 stereo set, recorded before and after we fitted new magnets and ribbons. Here they are…
‘Blackbird’ recorded with his stock BM5, before the modifications
“The difference is amazing. The mic sounds awesome now. It’s about 10-12 db louder (needing only 52 db for the front for finger picking now) and it has got much more treble and presence. Still it sounds smooth and wonderful rich, without losing the transients. This mic is killer for acoustic guitar now, and also as a room mic. I also compared it to my modified RB500 Mics (with cinemag 9888 Transformers) and the BM5 now has 6 db more output and is sounding so much better. Also the Beyer M130 doesn’t match it by far, IMHO.
“Both were recorded with the BM5 (60 degree angle pointing towards neck and bridge) into a TRP Ribbon Mic Pre direct into RME Converter into my DAW. No lowcut. The older recording would have been 10-12 db lower with the same TRP-Gain. For a better comparison, I choose to normalize both files. Still the new one sounds louder, brighter and more detailed. The noise floor of the older recording is clearly audible, and unnoticable with the new one – due to the 12 db more output of the mic.”
Update 21 Feb 2015.
Here are some comments from Andy at Superfly Studios in Nottinghamshire, UK, about his B&O BM5 with magnet upgrades and new ribbons.
“I’m so happy with these microphones. They have been absolutely fab to use over the past few days.
First session in was an acoustic folk duo, I used the B&O BM5 on one of the guitars and it just sat straight into the mix and sounded great. Picked up all the detail of his picking and sounded nice and rounded on the full-on sections. Just the right amount of highs for my taste as well, I normally use a 414 for acoustic and cut some of the top end, but I’ve got a new favourite now.
Also used the B&O for the drums today and it sounded great in the room, I love using room mics on drums and had the beeb reslo’s as a spaced pair about 8 ft away (10ft apart). Seems to always do the trick in the live room and the B&O just in front of the kit at waist hight. Sounded fantastic lovely sustain to the cymbals and picked up the natural ambience of the room.”
Sadly we don’t have the mount, but as this shares a connector with the Reslosound mics, we can use a Reslo stand mount for it. None of the other parts are common to the Reslos, so they must have just sourced the connector from them.
Inside, the mic is a fairly conventional figure-8 ribbon mic, but has added baffles both sides of the ribbon, and thick wires run from the top ribbon clamp, giving some blast protection along the way.
The ribbon motor uses tapered triangular pole pieces, which compensate for the decrease in magnetic field with increasing distance away from the two block magents, and ensure a more even magnetism along the length of the ribbon.
And of course there is a suitable transformer in the base to convert to a sensible impedance – in this case 50 ohms. The mic sounds rather nice, rich and dark close up – it may make a vocal session very soon!
B&O were justifiably proud of their mics being chosen for the UN – here is a document from the time…
And a translation from the Danish….
“As we previously mentioned to you, we have received a message from our US representative, Fenton in NY, that the UN uses our BM3 microphones throughout the UN building in NY. They chose the B&O mic and an American mic because only they, out of several hundred different manufacturer products that were tested, did not give rise to any acoustic feedback in the several hundred loudspeakers that are mounted in the ceiling of the UN general assembly building. Our mic also had an advantage over the US product as it didn’t hide the speaker’s face, which is important with regards to film and TV reporting. The microphones have been in use in the UN since 1st October this year. The newspaper INFORMATION recently had an article with a picture that depicted the Canadian foreign minister , Lester B. Pearson , at the podium in front of B&O microphones when he presented his suggestion for involvement in Egypt. Via our advertising bureau we managed to send out a press release under the title “Danish microphones at the UN podium”, and a whole selection of magazines included the picture and advertisement. We have attached the picture for your information – Next time you see the program AKTUELT in TV with recordings from the UN building, take note of our microphones, they are clearly visible.
“Our American representative has also undertaken an investigation that shows B&O micophones are used at, amongst others:
[Mercury, ABC and Decca]
“We have large orders from Fenton conmpany for microphones and pick-up units, and the advertising that Fenton performs in the American technical journals has the effect that we receive requests from other countries. This has resulted in that we have recently sent 10 samples to Australia and samples to Hong Kong, and other countries are also showing interest.
“Likewise we have significant orders for AC motors from Norway, where we compete with German and English manufacturers, and samples of this product has been sent to other countries.
Some Bang and Oulfsen BM5 stereo ribbon microphones are prone to hum on one channel. This is because the top half of the mic rotates around a plastic collet ring, but is only grounded through contact to the lower half of the metal body. With time and use, the contact between the two halves becomes loose, and the upper body is no longer grounded properly.
B&O BM5 stereo mic
The problem only occurs with early versions of the mic. Later, B&O recognised the problem and re-designed the mic’s rotating ring giving it an additional metal lip, so that the upper mic rotates around metal, ensuring good grounding contact at all times.
If you have a an early mic, in most cases the hum issue can remedied by improving contact between the parts as follows. Here are some tips, but remember that there is a delicate ribbon inside, so go slowly and if in doubt send it to someone more experienced!
1. Carefully remove the top half of the mic, and loosen the two grub screws at the base with a screwdriver of the correct size. Don’t lose these little screws – if you do then they are M2 thread!
2. Slide off the ring and put the rest of the mic somewhere safe.
3. Flip the ring over and rub over some fine abrasive paper to remove any dirt and oxidation.
4. Gently run the fine abrasive paper around the bottom of the metal tube that will make contact with the lower ring.
5. Replace the lower ring and tighten the screws, making sure that the metal parts are properly aligned and make good contact. You want a close fit between the tube and ring.
6. If that doesn’t work, addition of a strip of copper tape to the plastic collet can improve the electrical contact between the two parts. The tape will eventually wear out if the mic is constantly rotated, but many users tend to keep the same angle for most applications.
