April’s MOTM was a nice old Framez ribbon mic, and its chunky Meazzi sister also made an appearance. Here’s the article… and here are the microphones:
I’ve had the opportunity to compare these in the anechoic box – here’s how they look (click to enlarge).
Frequency plots for Meazzi and Framez mics
The Meazzi has an overall flatter frequency response, but in both cases there is a significant peak around 4KHz, which should add attack to recorded percussion and clarity & presence to vocals. The Framez is slightly more sensitive in the mid range, but falls away somewhat below 150 Hz.
Whilst revisiting these mics, it is worth looking at the Meazzi’s perforated backplate resonator, which contributes to the pickup pattern and frequency response.
(Nb. Both microphones were fitted with 1.8 micrometer ribbons and wired for low impedance.)
Another typical day at the Xaudia studio & workshop…
Outside the studio …. flowers, blue sky and cows.
And inside, in the basement workshop…. a Reslo production line!
We see a lot of these little British microphones. The original ribbons are quite thick and have an unusual ‘square wave’ corrugation. Very often these have oxidised and become noisy, and after 50 years they usually benefit from a clean and a fresh ribbon.
April’s microphone of the month (MOTM) is this glamorous shiny blue ribbon microphone by Framez (not to be confused with Framus!)
This has no model or serial number, but is probably from later 1950s or early 60s. Framez were an Italian brand related to Meazzi – according to one source the name is a contraction of Fratelli Meazzi (trans. Meazzi Brothers), which does sound plausible. Framez / Meazzi also made some cool oddball guitars, and were associated with Wandré Pioli. Fetish guitars have much more information about these guitars.
Back to the microphone! This looks very much like a copy of the RCA 74b ‘junior’ microphone, but us physically somewhat smaller. And it is a pretty good microphone in its own right. The magnets have retained their strength over the years, measuring a healthy 4500 gauss between the pole pieces. It has a hefty transformer with taps for both low and high impedance, making it suitable for both recording and PA use.
This one arrived with a thick flat ribbon – probably a DIY ‘kitchen foil’ repair. With a proper 2.5 micrometer ribbon installed, and the mic rewired for balanced, low impedance operation, the sound is clear with a strong output, just lacking a little of the low end proximity boost that you find with many ribbon microphones. The ‘low’ impedance tap is 1:45 ratio, which gives around a 450 ohm output with the 2.5 micron ribbon.
I’m actually very impressed with this little microphone, and it looks great too!
Update 23/4/11
We managed to get hold of a Meazzi ribbon microphone for comparison. It’s a little less glamorous, and has a similar ribbon dimensions, but a very different motor assembly.
A few months ago I wrote this blog post about the strange things that I had seen inside ribbon microphones. In those cases the ‘strange things’ in question were put in there deliberately by previous owners or techs trying to repair or improve the microphone.
Since then I have come across a couple of microphones which contained even weirder things – insects!
Before modern foams, felted wool was widely used in microphones for shock mounts, wind shields and the like. Unfortunately, moths love this stuff too.
Here’s an old STC4033. You can see the moth eggs on the lower block of green felt.
Worse still, one of the moths had become lodged behind the ribbon:
Moths also seem to like the wool lining and felt mounts on AKG D12s – here you can see the eggs and damage to the lining in the inside corner of the grill:
Anyway, I guess the lesson to be learned is that microphones should be stored in dry, clean places and not in the garage, or at the bottom of the wardrobe.
As you may know, I study quite a lot of vintage ribbon microphones. In general these are simple devices, with just a ribbon, motor, magnets and output transformer . The details and quality of the parts may vary, but most have the same mode of operation. But just once in a while something surprising comes along. Like this Shaftesbury Velodyne Supreme microphone, which is a ribbon microphone with a twist.
The output of a ribbon mic will scale in proportion to the length of the ribbon, at least up to a point. The idea behind the Velodyne was to give increased output by using a super-long ribbon. Normally that wouldn’t give you as high an output as it should, because of ‘rippling’, or other incoherent vibrational modes. But by fixing the ribbon in multiple places they claim to avoid this problem. The microphone was sufficiently novel at the time for the inventors to apply for protection.
Well that’s the theory. In practice the microphone has one giant ribbon that goes round corners, and each length of ribbon has a ‘node’ in the middle, so in total it has 8 elements, each at 45 mm x 4 mm. So 360 mm of vibrating ribbon!
What is more, the microphone has no transformer! I guess the designer thought it had enough impedance already and did not need one. I wonder how well it worked? Sadly we may never know. The ribbon is broken in many places, and is glued down, so it will net be an easy thing to replace. I’m still struggling over whether to try and get this working or not. I suspect it really ought to be left in its historic condition, but I am curious about how it would have sounded.
Postscript: History shows that this design was not a success. Whether this was for sonic or economic reasons, we can only speculate, but Shaftesbury appear to have abandoned the concept. Their later ribbon microphones were a much more conventional affair, like this Shaftesbury RT model – ribbon, magnets and transformer.
February’s MOTM is a ribbon microphone made by Zephyr, of Australia. It’s nice to see a microphone that begins with the letter Z!
The mic has a very “retro sci-fi” look, with hammerite paint and a punched metal grill. The name plate reads “High fidelity velocity microphone type 30RA, but despite the misleading model number, the mic is actually a high impedance mode, and the output transformer is marked “50K’.
The magnets are still healthy on this one, kicking out around 2500 Gauss between the pole pieces. The ribbon is 2.5 mm wide and 28 mm long, similar in scale to a Reslo RBL or Grampian microphone.
The back of the ribbon element is covered in lots of felt, to stop air blasts and brighten the mic for vocal use. Removing some of this opens the sound up a bit. This beast was probably intended for use with a home tape recorder, and would have worked very nicely in that application.
The ribbon itself is mounted on a removable plastic saddle, which makes servicing very simple. Which is a good thing, because this one is stretched. This idea is also seen on Reslo and other microphones.
With a new ribbon, and a suitable impedance-matching buffer, the microphone sounds rich and full – well worth the time spent to get it up and running again.
After a morning with glue and a staple gun, sticking acoustic foam to the soft walls, our new microphone testing chamber is up and running. Here are a couple of photos….
The chamber is hooked up to pink noise and swept-sine equipment, and can collect a frequency plot in a matter of seconds. I’m still working on validation, testing different speakers and mics for best performance, but the facility is already proving its worth.
It’s been a quiet month so far for blogging, but a busy one at Xaudia.
We’ve spend the last week building a new microphone workshop in the basement below the studio, including an ‘anechoic’ isolation booth for mic testing. Ralph & Jane have been helping out with building and painting.
Here’s the empty room, waiting to realise its potential:
Wall going up…
A door, window and a slap of paint
Isolation booth and test and measurement area…
And with the test gear going in:
The door on the left is an isolation / semi-anechoic box for testing mics or punishing drummers. The sound treatment is on order.
A few months ago I was trying to find some thread adapters for a customer with an old RCA junior ribbon microphone, who wanted to use it with a modern standard 5/8″ microphone stand. Most suppliers were charging around $25 dollars, plus post and the inevitable import and handling duties.
So we decided to make some.
These fit most of the ‘big’ vintage RCA microphones, including the 44, 74b and 77 ranges, and also are perfect for Sony professional mics, including the C38b, FV300 and C48 microphones. They also fit Syncron AU7A / Fairchild F22 microphones, and several other American and Japanese microphones with a large thread.
Update:
These are now for sale on the Xaudia website priced at £6.00.
