01Dec DIY audio interface ideas
I’m working on a more advanced DIY audio interface for those of you asking for more interface options. The chip in the center is a stereo amplifier and all of the support components needed for it to operate are on the board. The nice thing is that the whole board is about the size of a compact flash card.
The plan is to use two of these xlr/1/4 inch combo jacks for inputs with two independent volume controls and a 3.5mm output. I wanted to get your input on any other features you would like to see in a low price audio interface. If all goes well I should be able to keep the price under $40.
Here is the basic design if any of you have anything to add. I’m debating on squeezing two of these chips onto the same board so that you could also include headphone monitoring. I’m still waiting on a few more parts to come in, once they show up I’ll post some audio tests.
December 1st, 2012 at 4:35 pm
so cool man! awesome.
December 1st, 2012 at 5:41 pm
My GH1 doesn’t have any kind of headphone monitoring so that would basically be a requirement for me for any kind of external audio source.
I am really interested to see the finished product. Smaller is always better in my eyes, and this looks to be pretty small!
December 1st, 2012 at 7:28 pm
Good thinking on the combo jacks. If the preamp quality is good then I would definitely be interested.
Headphone monitoring at different points in the chain is useful, but since the audio could still get messed up (bad cable, etc.) between this device and the camera, it cannot be depended upon and thus I would not want it included if it would increase bulk or price too much.
What type of power requirements will this thing have?
Not really related to the electronics, but good mounting points on the housing would be very useful. At least 2 1/4″-20 mounts would be ideal I think (one for device > camera, another for device > QR plate, etc.)
I use a DR100-MK2 but due to it’s bulk and power requirements, I don’t use it in production nearly as much as I’d like to. If it’s similar in size to the iRig Pre (or rather 2 of them since this will have 2 inputs), I would definitely be interested.
December 1st, 2012 at 9:12 pm
Hoping to get this running on a single 9 volt battery. If I add headphone monitoring it adds about $15 to the price of the board and you are right, it’s still before the camera. This is still in the prototype phase. I need to test audio quality and run it through the paces, but I’ve been trying to come up with a good reason to have a laser cutter around, so if this ends up become a noob store item, I should be able to design the case and mounting points to be has useful as possible.
December 2nd, 2012 at 11:03 am
Audio monitoring before the camera is a million times better than no audio monitoring at all. I chose the Sony wireless mic over the competition solely on it having a headphone monitor. I would gladly pay the extra $15 if that is what it took to get it included.
December 2nd, 2012 at 4:03 pm
True, it is better, but at the same time, it’s a false sense of security. I was putting together a package for a shoot on a GH2 (no headphone out like the GH1) and was testing the audio from a wireless mic. From the headphone out of the wireless receiver, everything seemed ready to go. However, while audio level meters on the camera’s LCD were responding to the mic input the levels were within range, something just did not look right.
I recorded 30 sec on the camera and had a listen– totally unusable. The cable between the camera and wireless receiver was bad and needed to be replaced.
So while audio monitoring at different points in the chain is useful, it’s ultimately pointless without monitoring at the recording device (this is the reason for the DR100-MK2).
@Deejay: Since adding the headphone output will likely add at least 40% to the price (considering the material costs), how about two options (with & without headphone output)?
December 1st, 2012 at 8:39 pm
the only things that come to mind are headphone out,3.5 mic out, phantom power. I guess a 1/4 inch thread on the top and bottom of the casing so we can attach it to camera or attach things to it. if you would keep it to a 2.5 x 2.5 smaller cube you would have a product many would buy and invest in. or at least I would. you can call it “the Cube” or “the audio cube” lol Your site is always the best because you come up with things all the time.
December 1st, 2012 at 9:13 pm
Headphones are a maybe, phantom power is out unless I double the final price. Mounts will defiantly be there. Thanks for the input!
December 1st, 2012 at 9:42 pm
Why not keep it mono and have 1 input and 1 headphone out?
Another idea, have 1 neutrix combo and 1 mini plug for lavaliers & prosumer shotguns ie rodevideomic.
How about this idea. If you use two stereo chips.
2 Neutrix combo’s, 1 miniplug, 1 headphone.
Not sure if thats possible but it covers a lot of situations.
December 1st, 2012 at 11:14 pm
Still the newbie here : ) What exactly is an audio interface? I just switched from the JuicedLink DT454 to the iRig with mod and extremely happy with that transition for the type of videos I produce. Would this be something between the iRig and a JuicedLink device? I just wish I had audio monitoring without having to run Magic Lantern on my 5D MkII. I did successfully install ML but for the life of me just seemed to be overly
complicated to me just to get the audio monitoring. Anyway I want to say I am interested : )
P.S. DeeJay you need to create a Classifieds section on here. I have a slew of stuff I would love to sell and I hate dealing with eBay/Craigslist!!! Just a thought : )
December 2nd, 2012 at 4:40 am
Looks a great concept – How about accommodating it within a battery grip, in the second battery recess taking power from the one battery?
Perhaps a module that replaces the original grip door so you have the fixed amplifier section and a half door for battery access.
I think headphone monitoring is very worthwhile.
December 2nd, 2012 at 9:52 am
The battery grip is a great idea, however I don’t have the injection model equipment needed to go that direction. This will most likely be in a small box of some kind. The idea being that you buy the kit and then do a small amount of assembly at home which keeps the price on everything low and gives people the option of hacking, modifying, or changing the design in what ever manner they want.
December 2nd, 2012 at 10:48 am
I thought that is what 3D printers were for 😉
December 2nd, 2012 at 9:34 am
I have been waiting for someone to design this. Thanks
I vote for 2 XLR inputs and a stereo mini input for wireless mic and no audio monitoring. I just think HDSLR manufactures will be stepping up. (Like the GH3)
I have friend with a very small business who uses a laser cutter. Email me if you want his contact info. He is in Cal.
Thanks again for this. Great idea! Rjett
December 2nd, 2012 at 10:57 am
I’m thinking XLR without Phantom Power isn’t a great advantage. You might as well stick with a 3.5mm jack, perhaps with a switch to swap between linked stereo and balanced input.
December 2nd, 2012 at 1:18 pm
Agree, since it will not have +48v on the XLR, what about put 2 mono 3.5mm inputs with independent volume control, line out and a headphone jack?
3.5mm connectors are much smaller than the XLR and will help to maintain small factor
December 3rd, 2012 at 9:03 am
Hmmm. The perfect device would be…
Two XLR combo jacks with phantom power (take apart the iRig pre to see how they did it)
Independent Gain adjust (like the iRig pre)
Two 1/8″ jack Mic Level out
1 switchable mono/stereo line level/headphone output (with volume control)
I’d pay $90 for something like this.
December 3rd, 2012 at 5:04 pm
I could probably design a case for two I rig pres and add some headphone monitoring I just don’t have the equipment to do more then two trace boards. Which means I’d have to find an off the shelf design.
December 3rd, 2012 at 10:33 am
Also, wouldn’t something that’s pre assembled be a decent option. Like the Art Pro Audio Dual USB Pre. I believe it runs on a 9v battery.
http://artproaudio.com/art_products/signal_processing/usb_audio_devices/product/usb_dual_pre_ps/
February 3rd, 2013 at 10:34 pm
That thing is too big and looks like it requires an external power source
February 4th, 2013 at 7:32 am
It’s about 1 1/2 inch by 1 1/2 inch and will run on a 9 volt battery. Should be smaller then most other offerings.
May 1st, 2013 at 11:25 am
It’s been a while, so I was just curious how this adapter was coming along. I would love to put one of these to use in upcoming shoots.
May 1st, 2013 at 7:29 pm
Got it working, trying to find someone to manufacture it before I post more info. Trying to get it done between other projects.
May 2nd, 2013 at 5:48 pm
Thanks for the update. Kickstart it!