Wednesday, February 28, 2018

Laser Cut Shock Mounts

I received two new ISK Pearl microphones. These come with hard clip mounts only, so I decided to try making some shock mounts. Researching designs for SDC microphones I found many that use crossed shock cords to hold the microphone in place. The microphone body is slipped between the crossed shock cords. The issues I see are that the microphone can easily slip out and they have a tendency to sag.

The design below incorporates an inner collar that holds the microphone body securely. The shock cords attach to the collar itself. Hopefully this will prevent the microphone from falling out and eliminate sagging.

I used part of an old hard clip to attach the new shock mount to the microphone stand. Rubber bands are used for the shock cords until I can find suitable elastic bands or make my own.

The design is very simple and is made from all flat pieces. These could be cut by hand, but if you have a laser cutter or access to one you can use this SVG file to cut the pieces in only a few minutes. I can provide the Fusion 360 files too if you want to use them as a starting point to create your own design.

Monday, January 29, 2018

Audio over Ethernet (update)

I needed to build more snakes but this time with XLR fanouts. I mentioned in my previous post that I was going to try using pigtail connectors instead of the breakout boards. I purchased a bunch of pigtails from ebay for about a buck apiece. The ones I selected have all the appearances of being shielded. However they are not. The cable has a foil shield but it is not electrically connected to the jack or plug. The solution was to solder a wire directly to the metal outer shell on the jack and then tie this to all the grounds of the XLR connectors.

The boxes for this batch were made on a laser cutter instead of using electrical junction boxes. They have all the right sized holes in the right places and they look much nicer. It is not required to mount the end in a box but it does add a layer of protection and improves handling. 

Thursday, October 19, 2017

Audio over Ethernet cable

I recently learned that it is possible to send four channels of balanced audio over category 5 or 6 shielded ethernet cable. What makes this especially interesting to me is that it solves some audio distribution problems that I've been trying to see my way through. The tracking room currently has only one place where all microphones and instruments connect, a multi-channel snake sitting in the center of the floor. While this works it is a constant effort to maintain all the cables in an orderly fashion and out from under everyone's feet. Plus it just looks bad.

I would like to have XLR connectors mounted on the walls near where each musician sits so that the cables could be neatly tucked out of the way. This would also provide monitoring and really de-clutter the room.

There are also other rooms that would be great for extending capabilities. The living room has nine foot ceilings and a good vibe. Running mic cables here to isolate instruments or singers during recording would be a great option. But the path from the desk is long, meaning a bunch of long XLR cables or a multi-core snake that would have to be run for every session and then rolled up and put away after.

The actual distance is pretty short if I were able to go through the floor. That would mean putting a decent sized hole through 100 year old inlaid oak flooring. Not at all my first choice. I discovered a hidden spot where a previous owner had drilled a tv-cable sized hole near the edge of the baseboard. The diameter is too small for a multi-core snake or even a single XLR connector to fit through but a Cat5 cable passes through with just a slight push.

Commercially made products like the ETS Instasnake provide three or four balanced signals and terminate in XLR connectors. It feels kind of expensive at $185 per box (you need two to make a snake.)  Radial Engineering also has a nice product at similar prices. Redco has a product that runs $132 for the set of two boxes. In all cases you need to provide your own Cat5 Sheilded cable.

I really liked the idea of balanced audio over Cat5 cable so I looked at how I could build the termination boxes myself. It turns out that it is much easier than I expected. So here is how I approached it.

Cat5 Audio over Ethernet Snake

A basic audio over Ethernet snake consists of an Ethernet cable that plugs into a box on each end that has XLR (or TRS) connectors on it. A commercially made unit is a metal box with up to four audio connectors and one RJ45 connector. The RJ45 connector allows you to plug in a shielded Ethernet cable and provides four twisted pairs plus ground. The RJ45 connector is wired to the individual XLR or TRS connectors inside the box.

Finished snake input box and pigtail end
There are many different configuration options for each end. I decided to have a box with female XLR connectors on the input side for microphones or instruments and terminate the other end with a pigtail (four XLR  male cables ) to connect to my mixing board. This is a completely modular setup so it is easy to swap out the end components to suit the application.

The XLR Box

Parts Express sells an XLR panel box with four female connectors and 4 TRS jacks pre-mounted for under $18 shipped.

PartsExpress XLR box and MDFLY RJ45 Breakout board
To complete the box all I had to do was wire in a RJ45 connector. I chose an RJ45 breakout board from MDFLY Electronics because the connections are made via screw terminal and this would allow me to experiment easily. Soldering would probably be better but this was really easy to wire up as a prototype and allowed for mistakes. These were $2.48 each on ebay.

RJ45 connector mounted inside box

This made the total cost of the termination box $20.

The box has knockouts for passing cable through or mounting a connector . The location of the knockouts did not allow me to mount my connector without hitting the XLR and TRS connectors inside the box. I had to nibble s slot for the connector so that it was out of the way. Choosing a different type of connector might alleviate this issue. For my next boxes I will experiment with a connector type that has a pigtail already wired in. See below.

The Pigtail

There is no reason you cannot build a XLR box for each end of the snake but the box from Parts Express only comes with female connectors. I thought that would make for extra wiring and adapters to connect to the mixer so I made a simple pigtail instead.

I found inexpensive four channel XLR snakes on Amazon that I could cannibalize. Easier and cheaper than making my own as the XLR connectors are already soldered on and I just cut off the length I wanted. The RJ45 connector was mounted inside a cheap electrical junction box to protect the wiring and secure the cables.


There is nothing complicated about the wiring. The signals just need to match at each end. I made a diagram for the connections and then used my multi-meter to test each connection as I made it. Then one final check after assembly.

There is probably an industry standard for wiring but I don't have it. I wired the connectors as shown below. All Color/White wires are Hot. All Solid Color wires are Cold and the Shield is Ground.

What I Might Do Differently

The placement of the knockouts in the XLR box make it challenging to mount a RJ45 connector. I don't have a punch for making the correct size and shape opening in the box so I would still use one of the knockout holes. The connector shown below looks like it would mount in the existing knockout hole and provide enough clearance. The plug end could be cut off and the individual pairs soldered to the XLR connectors directly. I could even mount one of the breakout connectors inside the box and use this type of connector like a short extension cable. This connector would also work well for the pigtail end where you would solder directly to the XLR or TRS cables and not need a box to mount the RJ45 connector in.

Caps to block phantom power on the TRS jacks would also be a good idea.

Cat5 Shielded Extension Cable

XLR box and Cat5 cable
Making the snake took me  a couple of hours of planning and soldering but in the end I saved somewhere between $100 and $300. I have four more to make so the savings is very real and gives me the option to customize during fabrication.

Thursday, December 17, 2015

Zoom H2n Microphone Stand Adapter

Zoom H2n Microphone Stand Adapter with a 1/4 inch TRS Jack as an additional feature.

Zoom H2n Microphone Stand Adapter

I needed a microphone stand adapter to hold my Zoom H2n. I use the recorder during live shows as an additional stereo microphone. I use the line out jack to send a stereo signal right to the mixing board. The adapter that Zoom sells for this purpose will hold the recorder in a microphone stand just fine but I wanted to find a way to secure the cable that goes into the 1/8 jack more securely.

This adapter has a 1/8 plug at the top that goes into the line out jack on the recorder and a 1/4 TRS jack on the bottom. This provides a secure strain free connection to the recorder and allows plugging a 1/4 TRS stereo cable into the bottom of the adapter that can then feed into the mixing board.

Making the adapter

I started out with a donor body from a broken hand held dynamic.

The first step was to remove the capsule and internal components. Then I unscrewed the upper portion of the body.

This piece was then machined to create a recess to allow for access to thumb screw for holding the recorder to the top plate.

Next I cut a slot in the top of the lower portion of the body.This slot allows the cable to pass through.

Slot cut in lower body
Top and bottom screwed back together

Next I cut a top plate from a piece of bamboo plywood.

The upper piece of the body was epoxied to the top plate with a 1/4-20 thumb screw inserted through the hole.

The cable used internally is a Hosa 1/4 to 1/8 right angle adapter.

The 1/4 inch end was epoxied into the bottom of the microphone body with the 1/8 inch end running out of the slot in the side of the body. A rubber grommet was attached around the cable to prevent damage.

Screwing the sections of the body back together completed the adapter.

Here is the finished adapter with the Zoom H2n recorder mounted.

Completed adapter

Sunday, March 16, 2014

DIY Studio Monitor Isolation Stands

I needed to raise my studio monitors 10 inches for the proper alignment and to isolate them from the desk they sit on. A quick look on the internet shows some pretty nice options for doing this. I really liked the IsoAcuostics stands when I saw them and I felt I could put something together pretty easily that would provide the positioning and isolation I needed.

My first thought was PVC pipe with three way elbows. Thinking more on it I came up with an even simpler design that uses a bracket at the top and bottom of the stand to hold the PVC sections and then some rubber feet to provide some isolation between the stand and the desk. The monitors came with isolation pads that could be used on the top of the stands under the monitors.

I sketched up the brackets in my CAD program and then cut them out in bamboo on my CNC machine.

Bracket cut out on CNC machine

Brackets and PVC sections
Each stand is made from two brackets and four 10 inch sections of 1/2 inch PVC pipe. The PVC pipe is positioned into the holes in the bottom bracket and gently taped in place with a mallet. The fit is snug and there doesn't seem to be a need for any adhesive to hold them in place.

Next the top bracket is fit to the pipe in the same manner.

Brackets and pipe assembled

I found some rubber pan nuts that fit perfectly into the 1/2 inch PVC to be used for the isolation feet. These were just pushed into the ends of the PVC.

Rubber pan nuts used for feet.

View of a rubber pan nut.

Completed Stand with Monitor (no feet on this one)

Sadly my local Lowes only had 7 of the rubber pan nuts so I still need to find one more to complete the second stand.

They seem to do the trick nicely. They are surprisingly rigid and have no trouble supporting the monitors. Sound is improved and there is no noticeable resonance from my desk. I had planned to fill the PVC with sand to dampen any resonance in the legs but I think the monitors are effectively isolated as they are. So there you have it, simple effective and extremely low cost studio monitor isolation stands. 

Friday, November 29, 2013

Exploring the Darkness

With Thanksgiving behind it was time to take the little EOS M and panohead out for some practice. When I'm in need of some inspiration I have a favorite location that always seems to get me kick started. What I didn't count on was that location being closed up and dark. Even in the darkness though there was something new to experiment with. 

Friday, November 1, 2013

Photo Technique Magazine

November/December 2013

Check out the November/December issue of Photo Technique Magazine to read my article on making the move from Large Format to Digital Photography using techniques such as stitching and HDR to achieve the look and feel of film.