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My DIY compact low noise 3-mic MS setup with Zoom F6
Old 3 weeks ago
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My DIY compact low noise 3-mic MS setup with Zoom F6

Hi, just wanted to make a post to thank all the gearlutzers I got info from by lurking on this web site, and give back some info in case someone finds anything interesting for their own need.

I recently started being interested in sound recording as a hobbyist, wanting to be able to do some sound capture here and there, for instance to record my daughter's school choir concerts, which most often take place in churches

The setup had to be low noise (I find hiss disturbing) and compact, so it could be transported in a standard backpack.


Mics

Since I wanted a small footprint I opted for a MS (cardio + Fig8) setup because the mics can be all "sticked" together.

MS also has the advantage to be able to "dial in" the amount of reverberant sound you add to the mix, so I thought it could be useful to be able to reduce a little of the reverberation of the churches to hear the singers better.

I also added an omnidirectional mic to be able to capture low sounds from organs when the choir plays with in a church, hence the 3-mic (I got this idea on this forum)

Fig8:

I decided to use a "true" Fig8 , not side to side capsules, so I went for a ribbon mic. I didn't want to try one of the low cost chinese stuff and be disappointed so I bought a BIV 1 from Igor in Russia after having reading all the good stuff on him here.
Here's the link on the GS thread : RM BIV Ribbon Microphones

I had a couple concerns about noise because it was mentioned on the forum that ribbons could be noisy, but it's not the case at all with the BIV.

Cardio/Omni

At first I used 2 Behringer B5 with cardio/omni capsules, but I found I didn't get enough choir presence when sitting at some distance, so I bought a second-hand Rode NTG1 with a supercardio pattern to have better sound focus.


Noise
Apart from the the mics internal noise, noise cause is
*vibration transmission noise to wise through the mount and through the cable
*cable noise.
Vibration noise
To avoid vibration noise transmission from the stand, the mics are mechanically decoupled from the stand with a Rycote USM shock mount.

To avoid noise transmission from the cable, 3 mics are wired using very flxible pigtails to a 6 pin XLR and run down using a single cable to avoid cable clutter.

To reduce weight and size, I used pre cut XLR connectors from OPS https://www.ops-shop.de/

Cable noise
Concerning cable noise, at first I used 4 pair Mogami 2931 but I found out it was very very noisy, if I touched the cable, or moved the cable, it would make big clicking noises.

This made me make some research about microphonics, ie cable generated noise, and it appears that when you touch or move the cable , there might be some dielectric charging in the conductors that ends up in mini ESD that creates clicks , and moving the cable can also create some tiny inductance change in the cable that can generate noise.

A logical solution to this issue is to use cables where wires can not move one against another, so I decided to use a Belden network-derived cable 1305 that uses bonded pairs, ie the wires are twisted and glued together.

Using an network cable means the cable is not shielded, but is not an issue since the cables are so tightly twisted and bonded, there is no inductive surface that can capture any noise. Actually this cable is dead silent, no hum, no buzz no anything. Only "issue" with this cable is that it's not very flexible.

For the pigtails, I used the same idea and went for Mogami ultraflexible(for vibration filtering) 2794 that has bonded together wires as well.

To minimize RF noise, the phantom powered mics use Neutrik Capactive-coupling EMC connectors.


Cabling

The 1305 has 4 pairs, so each mic uses 1 pair, and the last pair is split in 2 and is used as the ground for the 2 phantom powered mics. So the 8 connectors of the cable are used.


DAW

For the firsts tests I used a Behringer UMC404 connected to my Surface Pro using Reaper. It had good quality but it was creating some issues in the field, from touchscreen getting touched at inappropriate times, to forgetting to disable sleep on the surface and seeing it shutting down after 15 min :-)

So I needed a more serious , less stressful, system, and was struggling between zoom F4 and a SoundDesign , and software vs hardware limiters, when I found out about the new floating 32 bit recorders like the Zoom F6. I immediately thought is was going to solve one of my problems which was gain setting : with too small gain I would get quantization noise in post production, but with to large gain I would get saturation during clapping time, which is very loud in my case when compared to the music level since I'm in the audience.

The Zoom F6 settles this problem ! no more limiter, no more gain settings to chose : just record at whatever level and solve all the issues in post prod!


Stand

I saw a cool youtube https://www.youtube.com/watch?v=_EkV6mEuUz0 video on all the possibilities of a cullman magic 2, and how it can fit between seats, so I chose to go with it but it's not built anymore, so I found a good second-hand one on ebay in germany.
This stand is very compact, it folds flat and is only 35 cm long when folded


Visuals

I didn't want to be an annoyance to others by using anything shiny so I chose black cables and connectors, and put heat shrinking tubing around the shiny BIV and golden Behringer. I had quite a panic attack afterwards thinking I had blown a very hot hair dryer near the ribbon of my brand new BIV which was surely not recommended, but hey, it's russian-made and is issue free :-)

An issue with the black XLR connectors is that I intended to use the body of the connector as the ground connector : I used 6 pin XLR, that's 3x2 for Hot/Cold pins of the mics, and the ground goes through the connector body.
Unfortunately the black paint is not conductive, so I had to sand the connector bodies it to get some decent connection between them, but it is not providing to low-impedance expected from a ground connection, so I'll buy some normal shiny metal ones, and paint them black with a marker.


Video

I chose a second hand Panasonic V180, it's ok for the project and very light. Good thing with Panasonics is that you can start recording and close the screen, it will continue running, so you're not a light nuisance to people sitting behind you.


Post-Production

I used Adobe Audition a couple of times , I like the software (I still have my Cool Edit license !) but Adobe makes it too painful to unsubscribe when you don't need it any more so I bought Acon Acoustica, which I found recommended here, and it's a very good software that does all I need (basically Filtering, Denoise, LUFS calc and a couple VST from time to time).

You can check it here : https://acondigital.com/products/aco...-audio-editor/


Demo :

Here' the video of my last Christmas concert recording, I find the sound quite good :https://www.youtube.com/watch?v=4Mn1wj0ddnU
Recorded in Versailles, France.

Sound is still detailed on very low levels like 5:46, and manages well on more powerful organ sounds at 19:11
You can hear the low organ notes : there is a 10 second long 32 Hz-Low C at 22:50, this can only be captured with the omni mic, the cardio mic can not go low enough.


PostProd notes :

The cardio and ribbon mics (high frequency mics) are cut at 160Hz, the omni (low frequency mic) is cut at 140 Hz, this allows to tame a 150 Hz bump in the church response curve.

I did a very light 3dB denoise on the high frequency channels (ribbon and cardio) to remove a little hiss on the completely silent parts.

The organ was quite louder than the choir ; I found out the choir's lowest frequencies seemed to be around 350 Hz so I applied a -3 dB low shelf below 400 Hz to reduce a little the overall volume of the organ.

The clapping parts are much much louder so it's heavily compressed to have them around the same levels as the music.

That's it, setup is nice and running now, and everything fits easily in the backpack !

Thanks gearslutz !
Attached Thumbnails
My DIY compact low noise 3-mic MS setup with Zoom F6-p1.jpg   My DIY compact low noise 3-mic MS setup with Zoom F6-s-l300.jpg   My DIY compact low noise 3-mic MS setup with Zoom F6-mogami_2794_001_800t.jpg   My DIY compact low noise 3-mic MS setup with Zoom F6-p6.jpg   My DIY compact low noise 3-mic MS setup with Zoom F6-p5.jpg  

My DIY compact low noise 3-mic MS setup with Zoom F6-p4.jpg   My DIY compact low noise 3-mic MS setup with Zoom F6-p3.jpg   My DIY compact low noise 3-mic MS setup with Zoom F6-p2.jpg  
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