Beyerdynamic M260 N Repair

Beyerdynamic M260 N Repair

We have just acquired a classic ribbon microphone in the form of the Beyrdynamic M260 N circa 1965.  The seller said it was rattling and might not work so, personally, I wasn’t holding out much hope.  This is an interesting microphone in that it’s polar pick-up pattern is hypercardioid as opposed to the usual figure-8 associated with most ribbons, this is to do with the way the ribbon is mounted in the microphone.  It’d great on guitar cabs, hi-hats and sounds of a similar nature and boasts a flat frequency response from 40hz to 18khz.

Beyerdynamic M260N

Top removed to reveal the ribbon element

After bit of research I discovered that the windscreen comes apart in the centre, revealing the ribbon capsule. Upon opening it was fairly obvious what was causing the rattling sound, the plastic peice which protects the ribbon had come loose.  I managed to carefully unpick the entire piece to reveal the ribbon sat in the centre of the magnet.  The ribbon looked in very good condition, no marks, dents or anything.

Beyerdynamic M260N

Cleaning up the magnet.  Ribbon visible

Next I very carefully cleaned the magnet each side of the ribbon to remove some of the rust.  I use isopropyl alcohol and a swab, being very careful not to get any particles on the ribbon.

Beyerdynamic M260N

Re-assembly of the capsule.

Next some superglue was supplied to the outside of the magnet, again being careful to get it nowhere near the ribbon.  Only using the minimal amount.  The plastic cover was then re-fitted and the small pieces of tape re-attached.

Beyerdynamic M260N

Beyerdynamic M260N Repaired

The repaired microphone was then tested.  The microphone does not have the standard XLR fitting of a modern microphone instead having a Klein Tuchel type connector, fortunately I already have and old AKG which used the same connector so was able to borrow the lead for testing the microphone.

More information on this microphone model can be found here, at the excellent Martin Mitchell’s Microphones.

Systems Integration (Part 3)

Systems Integration (Part 3)

The second episode in Systems Integration: XLR Patching.

The studio has four wall boxes, only two of which are in the same room.  I wanted to create an effective way of getting these wall boxes  to the sixteen mic pre’s in the console, so I opted for an XLR patchbay, because of slight danger of using a jack style patch chord with phantom power (the power briefly connects to the wrong side first).  As the studio will be used by a variety of engineers and I also have some vintage ribbon mics, I wanted to make sure the patching was as logical as possible.

A great bulk of thee effort, involved with building this, was in bolting the XLR sockets into the patch panel, each socket requiring two tiny bolts and self-locking nuts.  This process, in itself, took a good couple of hours to work through all 96 fixings.

Once that was complete, I had to de-solder all the tails that previously occupied the end of the cables before I could move onto soldering them to the new sockets.

Once this was complete I cable tested every single socket on the panel and wall boxes for continuity and polarity.  Finding just two minor errors which were very easily corrected.  It pays to be methodical with these things.

And, here it is, the finished panel, all labelled up.  The bottom panel is the 16 mic pres in the Audient, and the top is the wall boxes.  Of course, this also means I have effectively created a “wall box” in the Control Room too.

Should be incredibly easy to route signals from now on.

Systems Integration (Part 2)

Systems Integration (Part 2)

There comes a time in every studio owners life when s/he has to face the prospect of wiring four (often lots more) 96 point patchbays!  The main decision is whether to do this yourself or get a decent wire-person to do it.

I opted for the former so, for most of this weekend, I have been wiring and soldering.  As I mentioned in a previous post, going for DB25 d-sub patchbays made this easier and, opting for the Signex with solder pads for programming, the normals made it easier again.

Stage one was to assemble the parts.  As I already had the layout of the bays planned, I decided to print the identification strips next.  After half an hour or so changing column and row dimensions on Excel, I manged to print out some neat labels (I’m happy to share the Excel file if anyone needs it). Labeling the bays first made plugging in the DB25 to the correct connectors a lot easier.

The second stage was to half-normal three of the four Signex patchbays (see my Audio Geekery blog for more explanation).  This just involved bridging some solder pads, three per channel and took less than an hour; I can see why these bays are so popular with industry installers.

The normals on one Q-Patch took longer, every circuit board had to be rotated 90 degrees.

Every cable and patchbay was then tested using a cable tester to make sure there were no dry joints or issues with the cables.  I found a couple of issues with the cables, which were easily fixed with solder or manual manipulation of the jack/xlr connector.

Once the cabling and bays had been tested the lacing bars were installed…

…and, then, I spent the next day and a half cabling!

Here’s the final result.  Four Bantam TT Signex Isopatch bays, integrating all the outboard and the console.

I still have the XLR bays to solder and install, I’m waiting on some parts before I can tackle…

…next week’s patchbay challenge!

Systems Integration (Part 1)

Systems Integration (Part 1)

As promised, here is the post for my fellow audio geeks.

This week I have been planning patchbay layouts for the studio.

We have 4 wall boxes feeding into the Control Room as follows…

Wall Box 1: 16 XLRf, 4 XLRm, 4 TRS jack. Located under the window in the Recording Room.

Wall Box 2: 8 XLRf, 4 TRS jack.  This is found on the other side of the live room, near where the drum kit is usually set up.

Wall Box 3: 2 XLRf, 2 TRS jack. Located in the corridor between the Control Room and Recording Room.

Wall Box 4: 2 XLRf, 2 TRS jack. Upstairs in the lounge of the main house.

The Audient ASP4816 has 16 Mic Pres.  We have 28 XLR sockets, so a patching system needed to be designed.  Originally, I was going to bring the wall boxes and mic pres up on the bantam patchbays (more about those later).  However, jacks (of any sort) don’t mix well with phantom power due to the way they connect.  So, in order to protect the mic pres from inadvertent damage, I employed an XLR design to patch cabling back from microphone to mic pre…

I decided to build this out of panels, sockets and lacing bars.  I order the parts this week so watch this space for pictures of soldering!

To feed the jacks on the wall boxes, I choose to employ a standard (A type) jackfield, semi-normalled…

Quick, technical aside: Half-normal means that whatever is on the top, of each channel, is automatically connected to the bottom until you plug a patch cable in the bottom, of said channel, which breaks this link, like this (from the Signex Isopatch manual)…

Both these bays are located in the rack unit, directly under the window in the Control Room, this has several advantages. Firstly, it provides the Control Room with its own “Wall Box”, so things can easily be patched into the mixer.  Secondly, any additional equipment being used for a session can be placed on top of the rack unit and fed either to the console or into any other room with a wall box. Finally, by using XLR sockets for the mic pre patch, the phantom power issue is eliminated.

I’ve thought way too hard about this over the last few weeks, but nothing in comparison to how much thought I have given this…

This is the current layout for the main patch bay (to be located on the left hand side of the console).  This went through so many iterations: Bantam vs. JPO B gauge jack versions, lots of layout revisions, considering room for growth, adding the tape machine once it’s up and running, adding more outboard, etc.

The layout, as it turns out, was fairly easy, it tends to suggest itself as you start designing and moving blocks around.  By far the hardest decision in the process was solder tags vs. D-Sub DB25 connectors.  Solder tags are more reliable long term, but harder to change if things need updating.  After looking at more audio cable re-sellers sites than I care to mention, considering Neutrik, RE-AN (also Neutrik made), Switchcraft, Mosses & Mitchell.  I decided to got for the Signex Bantam TT DB25 D-Sub bays as suggested by Pete Miles on a Facebook thread about this very topic.

I made the decision to go with these for several reasons:

1. They are Bantam, so can fit a lot more connections into a small space.

2. Signex are a good brand of patchbay.

3. Pro Tools and the Console Bus Output are on D-Subs, so D-Sub to D-Sub cable are all that’s required for that part of the system.

4. A lot less soldering to do, just some pads to bridge on the channels I want to half-normal or fully normal, looks simple enough…

5. This is the important one: Once I get the tape machine up and running it’ll be easy to implement it into the patchbay, even if I have to move things around.  The thought of de-soldering and re-soldering the bays to accommodate “Analogue Warrior” (the Ampex MM1200) swayed me in the D-Sub direction.

Of course using D-Subs means thinking in banks of eight.  I can change the connectors on the end, but stuff in each bank of 8 going to the console, can’t easily contain stuff going to the other patchbay (although there’s always some way of doing it) which made it an extra challenge.

So I have four of these bays on their way to me. Watch this space for photos of ridiculous amounts of analogue cabling!

Using the system should show up any flaws in my layout plan but, as it’s on D-Subs, it should be easy enough to reconfigure … that’s the plan anyway!

Stu

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