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Shockmount solution for Coles 4038 Blumlein
Old 2 weeks ago
  #1
Here for the gear
 
Shockmount solution for Coles 4038 Blumlein

Hello everyone, I'm in search of ideas or solutions for shockmounting a Blumlein pair of Coles 4038.

I am currently using the AEA SMS bar and 4038SA adapters mounted on a lighting stand. The low frequency noises transmitted from the floor in the studio are severe. It is mostly from the performers feet, either while pedalling or simply lightly shifting the feet or tapping the floor while playing. Main uses are for piano and small ensembles.

My next step is to try some isolation pucks under the stand legs and if that works to try to mount the pucks to the legs somehow so the stand can be moved easily.

Has anyone else encountered this issue?

Thanks!
Attached Thumbnails
Shockmount solution for Coles 4038 Blumlein-coles-blumlein.jpg  

Last edited by soundmonkey; 1 week ago at 12:00 AM.. Reason: Corrected AEA adapter model #
Old 2 weeks ago
  #2
Lives for gear
 
🎧 10 years
Ideally, any form of vibration control would be tuned to the mass and resonant frequency of a given miking 'system'....which implies the total weight of stand, attached cables, mounting bar and mics. Clearly this is going to be different for a pair of lightweight German SD mics in an aluminium stand with a plastic Rode or 3D printed spacer bar vs a heavyweight pair of 4038's on a steel Starbird stand with AEA bar. The compliance behaviour of the wooden floorboards would ideally be taken into account too.

While these compliance and resonance frequency calculations (and necessary adjustments) are outside the skills of most location recordists, a few measures are possible. I'd recommend employing shock mounting at each 'junction point' within the system...aimed at spreading the resonant load (and hence possible vibration coupling) among several absorbers. So your idea of foam at the base of each stand foot, plus a shock mount for each mic....as well as one for where the stereo bar attaches to the stand... would be optimal, as this breaks the 'vibrational coupling chain' at several points. Ideally the transferred shock would be diminished as it crosses each such barrier ? You'll also firmly attach a loop of the cable pair to the stand....as the mic cables themselves are additional transmission points for floor vibrations.

I'm reminded of similar yet divergent approaches employed with monitor speaker decoupling from their mounting surfaces....such as sorbothane angle wedges, hydraulically damped frame structures or pointy feet. Think also of the vibration-reducing compliant mounts which decouple a car engine from the body/chassis....

Perhaps the mechanical engineers can chime in here....is a higher mass stand better than a low mass one at transmitting (or resisting) floor vibrations ? Or is it more a case of reducing the contact surface area between floor and tripod feet ?

Would adding mass to the system (think concrete paving stones, with a layer of bubble wrap or carpet underneath to protect and decouple from the floor) under each tripod foot lower the vibration breakthrough.

Or would the lightest stand possible, with compliant sponge under each foot, be more effective ?

I've probably raised more questions than provided answers, so maybe those mechanical engineers can chime in with practical advice ? Intuitively I think a 'tuneable' response to each system's individual resonant frequency would be best....perhaps a trio of pneumatic balloons or tyres under each tripod foot, which you'd inflate by pump to a low pressure to further decouple from the floor, would be a further engineering solution ?

Last edited by studer58; 2 weeks ago at 01:20 AM..
Old 2 weeks ago
  #3
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tourtelot's Avatar
 
1 Review written
🎧 10 years
I agree that something under the feet of the stand would probably help and then, how about a shock mount on the Coles? Maybe something as simple as the Audio Technica AT8410A suspensions?

https://www.bhphotovideo.com/c/produ...&lsft=BI%3A514

I have used them on a wide variety of microphones and find that they are pretty effective. Cheap too.

They hold up my Gefell UM70S mics so I think they would hold tghe Coles.

D.
Old 2 weeks ago
  #4
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hbphotoav's Avatar
 
🎧 10 years
While it's been a minute or two since I've thought about isolation like this, my pal Rich Mays (Sonare, RIP) was big on Sorbothane to decouple a tall stand from a resonant floor. I cannot speak to anything but his recommendation... for what that's worth. I'm sure there is other data out there as to whether it would work... but it (in conjunction with individual suspension mounts for the mics) sounded like a valid possibility.
Old 2 weeks ago
  #5
Lives for gear
 
🎧 10 years
The BBC used bungees on a heavy Agrippa floor stand.
Here is my version with Bronze PGS in MS.

Roger
Attached Thumbnails
Shockmount solution for Coles 4038 Blumlein-dscf5777.jpg   Shockmount solution for Coles 4038 Blumlein-dscf5780.jpg  
Old 2 weeks ago | Show parent
  #6
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orange's Avatar
 
🎧 15 years
Quote:
Originally Posted by Rolo 46 ➡️
The BBC used bungees on a heavy Agrippa floor stand.
Here is my version with Bronze PGS in MS.

Roger
hi Roger

how are the 2 mics 'fixed' together ?
Old 2 weeks ago
  #7
Lives for gear
 
🎧 10 years
Heavy duty cable ties
Plus a guard chain for public performance
Not really suitable for that , the whole rig is very heavy.
Sounds good though.
Old 2 weeks ago | Show parent
  #8
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orange's Avatar
 
🎧 15 years
Quote:
Originally Posted by Rolo 46 ➡️
Heavy duty cable ties
ahh - got it - I can see the cable ties now

Old 2 weeks ago
  #9
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emrr's Avatar
 
24 Reviews written
🎧 10 years
RCA 44’s had an attachment for flying with rope, which I’ve also seen used like the above pic on a stand.
Old 2 weeks ago
  #10
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🎧 10 years
My guess is that the bungee cords would be a very effective stand vibration de-coupler…even if attached to the AEA bar the OP mentions, rather than the mics themselves (as per Roger’s pic above). A square mat of artificial turf grass turned upside down under the tripod feet would complete the isolation exercise 👍 !
Old 2 weeks ago | Show parent
  #11
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🎧 15 years
Quote:
Originally Posted by studer58 ➡️
Perhaps the mechanical engineers can chime in here....is a higher mass stand better than a low mass one at transmitting (or resisting) floor vibrations ? Or is it more a case of reducing the contact surface area between floor and tripod feet ?
A higher mass stand will be better as it lowers the natural frequency and therefore the transmitted structureborne vibration to the mic, safely assuming you are concerned with frequencies above this natural frequency. This is why I use soft foam under the mic stand feet rather than just using an elastic mic suspension. With the stand involved, you are recruiting more mass.
Old 2 weeks ago
  #12
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DaveyJones's Avatar
 
🎧 5 years
The above solutions are obviously the best solution to fix the issue at the source.
However, as a location engineer I often get to the recording space having never seen or visited the place before.
I have become quite good at using tools such as RX and Cedar to remove this sort of LF rumble, foot noise and piano pedal thumps and, quite honestly, the results can be astonishingly good!

I have found that bringing suspension mounts for 30-40 mics takes up a huge amount of extra space, time transporting extra kit AND setup time due to more fiddly mounting. I also find that in the occasions that I things a are filmed or are also being performed to a live audience, that suspension mounts are very unsightly incomparrison to hard mounts. I therefore almost never take any suspension mounts with me and I've never come unstuck.

It does require more post-production time, but I'd rather save 30 minutes setup and pack down time (leaving time for moving mics if needed, and generalyl being less rushed) on recording day and then give myself an extra few hours in the calm and peace of my own editing floor...

Anyway, just a different point of view.

Dave
Old 2 weeks ago
  #13
Gear Maniac
 
A bungee rig seems like a good solution - one often sees some sort of short elastic suspension mounting M50s to the Decca tree; don't know if those are stock Neumann parts or a Decca kludge.

FWIW, here's a a shot of a Keith Johnson setup with pads under the stands. Can anyone tell what sort of material he's using?; it isn't the yellow-ish or black color one usually sees for foam; rock wool, maybe?
Attached Thumbnails
Shockmount solution for Coles 4038 Blumlein-keith-johnson-piano-setup.png  
Old 2 weeks ago
  #14
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tourtelot's Avatar
 
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🎧 10 years
There are a lot of small suspensions around. Not necessarily to fit the Coles, but they a around. Think the (fragile) Schoeps elastic mount, the rubber mounts for DPAs, or the excellent, effective and inexpensive Shure "donut". Both hardly larger than a Shure clip for an SM57. Gotta help, right?

I use a lot of the (fairly) small profile Rycote Lyre mounts a lot in both video and live work and they are never complained about.

But Dave is right about RX (can't speak for Cedar). Once a nice lo-cut "rumble" preset has been worked out, it seems to apply to most every venue, regardless. Pretty painless.

D.
Attached Images
Shockmount solution for Coles 4038 Blumlein-shure.jpeg Shockmount solution for Coles 4038 Blumlein-schoeps.jpeg Shockmount solution for Coles 4038 Blumlein-dpa.jpeg 
Old 2 weeks ago
  #15
Gear Maniac
 
I might add that stopping vibrations at the soure is much to be preferred over removing LF bumps in post. Floor noises are vibrating the transducers, which smears the sound in the time domain, and post noise removal will not address this.
Old 2 weeks ago
  #16
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tourtelot's Avatar
 
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So true as well, Mr. Brown.

I just stumbled on these on a quick Google search, and while they are probably not compliant enough to be of help under stand legs, I might buy a few to see what they can do. So cheap!

https://www.supplyhouse.com/DiversiT...ad-2-x-2-x-7-8

D.
Old 2 weeks ago
  #17
Gear Maniac
 
Those are often used by the Hi Fi crowd for putting under speakers.
Old 2 weeks ago
  #18
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hbphotoav's Avatar
 
🎧 10 years
So... is there no longer appreciation of Sorbothane Pads for decoupling stands from the stage floor...?
Attached Thumbnails
Shockmount solution for Coles 4038 Blumlein-sorbothane-pads.jpeg  
Old 2 weeks ago
  #19
Gear Maniac
 
Sorbothane is quite squishy - just wondering if two Coles on a heavy stand would compress these all the way to the hard floor.
Old 2 weeks ago
  #20
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tourtelot's Avatar
 
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Where can you buy those pucks?

D.
Old 2 weeks ago | Show parent
  #21
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hbphotoav's Avatar
 
🎧 10 years
Quote:
Originally Posted by tourtelot ➡️
Where can you buy those pucks?

D.
Quick trip to Amazon... enter: Sorbothane Vibration Isolation

https://www.amazon.com/Isolate-Sorbo...a-692662753862

I should add that (as I haven't deployed Sennheisers and/or Gefells in well over a year) that I have not tried these.

HB
Old 2 weeks ago | Show parent
  #22
Gear Maniac
 
Quote:
Originally Posted by tourtelot ➡️
There are a lot of small suspensions around. Not necessarily to fit the Coles, but they a around. Think the (fragile) Schoeps elastic mount, the rubber mounts for DPAs, or the excellent, effective and inexpensive Shure "donut". Both hardly larger than a Shure clip for an SM57. Gotta help, right?

I use a lot of the (fairly) small profile Rycote Lyre mounts a lot in both video and live work and they are never complained about.

But Dave is right about RX (can't speak for Cedar). Once a nice lo-cut "rumble" preset has been worked out, it seems to apply to most every venue, regardless. Pretty painless.

D.
A bit off-topic, but I like how Tony Faulkner attaches two of the Shure donut mounts to a regular stereo mic bar, runs what looks like a bit of aluminum bar stock through them, then hangs his mics from that; saves having to have each mic in it's own shock mount (especially with the 4-mic array).
Attached Thumbnails
Shockmount solution for Coles 4038 Blumlein-faulkner-shock-mount.jpg  
Old 2 weeks ago | Show parent
  #23
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by k brown ➡️
A bit off-topic, but I like how Tony Faulkner attaches two of the Shure donut mounts to a regular stereo mic bar, runs what looks like a bit of aluminum bar stock through them, then hangs his mics from that; saves having to have each mic in it's own shock mount (especially with the 4-mic array).
Yes that's an effective decoupling using the Shure donuts...but those interesting Neumann mic clamps raise my eyebrows.

If the following review is on the money, they seem to be little more than a visually arresting clamp, offering no vibration mitigation at all ! I'm sure it holds the mic securely....but that's about all it does ?

https://www.soundonsound.com/reviews...ced-audio-m600
Old 2 weeks ago
  #24
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tourtelot's Avatar
 
1 Review written
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199 Euro "suspensions" that don't suspend? Next you'll be seeing people buying expensive maple blocks to get their speaker wires off the ground.

D.
Old 2 weeks ago | Show parent
  #25
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🎧 10 years
Quote:
Originally Posted by tourtelot ➡️
199 Euro "suspensions" that don't suspend? Next you'll be seeing people buying expensive maple blocks to get their speaker wires off the ground.

D.
Surely you mean mic cables ? Not all 'homespun' inventions are so ill-advised however.....here's a mic holder which can effectively halve the usual number of suspensions required on location for paired mics. Interesting choice of plastic colour however...what's wrong with the Henry Ford approach ?

https://www.soundonsound.com/reviews...udio-mic-clips

As the article points out, it quite literally puts the weight of shock reduction onto 1 mic, and the Rycote Invision INV series wouldn't be up to the job, as they're tuned to a single mic's weight....so you'd need an alternate solution for this type of piggyback mount.

Back to the Coles 4038/Blumlein....maybe the 3D printing approach could deliver at least a lighter weight spacer bar ?

Last edited by studer58; 2 weeks ago at 07:42 AM..
Old 2 weeks ago | Show parent
  #26
Gear Maniac
 
Quote:
Originally Posted by studer58 ➡️
Yes that's an effective decoupling using the Shure donuts...but those interesting Neumann mic clamps raise my eyebrows.

If the following review is on the money, they seem to be little more than a visually arresting clamp, offering no vibration mitigation at all ! I'm sure it holds the mic securely....but that's about all it does ?

https://www.soundonsound.com/reviews...ced-audio-m600
I speculate that the theory behind these mic clamps is similar to that behind putting spkrs on spikes, rather than rubber or felt feet (or no feet). Minimal point contact, rather than larger-surface contact.
Old 2 weeks ago | Show parent
  #27
Lives for gear
 
🎧 10 years
Quote:
Originally Posted by k brown ➡️
I speculate that the theory behind these mic clamps is similar to that behind putting spkrs on spikes, rather than rubber or felt feet (or no feet). Minimal point contact, rather than larger-surface contact.
Minimal point contact would involve higher pressure per square inch....with resultant risk of denting the mic outer shell, particularly of a large diaphragm mic like the U87. The review describes the contact member as a pivoted plastic foot, which is hardly suggestive of minimal contact area like a speaker spike.

I'm sure it holds the mic very securely....but little or nothing more than that, as the reviewer alludes.

However, appearances would appear to be deceptive....as the extended list of glowing testimonial endorsements (incl Tony Faulkner) verifies: http://www.enhancedaudio.ie/m600-testimonials.html

I suspect the scope of this manufacturer's products goes well beyond the intentions of the OP's question, so I'll start a new thread related to it...

Last edited by studer58; 2 weeks ago at 09:54 AM..
Old 2 weeks ago | Show parent
  #28
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🎧 10 years
Quote:
Originally Posted by David Spearritt ➡️
A higher mass stand will be better as it lowers the natural frequency and therefore the transmitted structureborne vibration to the mic, safely assuming you are concerned with frequencies above this natural frequency. This is why I use soft foam under the mic stand feet rather than just using an elastic mic suspension. With the stand involved, you are recruiting more mass.
You clearly have some mech engineering and materials science credentials David....care to chew over some contentious laser Vibrometry and related data/assertions in a similar thread here ?

Enhanced Audio shock mount and mic stands
Old 2 weeks ago
  #29
Lives for gear
 
🎧 15 years
To hold the 4038 Vertically and assuming the mic shaft is 55-68mm in diameter then the Rycote USM-VB lyre shockmount may work ( rated to 900g vertical, 500g horizontal).

Last edited by Folkie; 2 weeks ago at 01:04 PM.. Reason: spelling
Old 1 week ago
  #30
Here for the gear
 
Thank you to everyone for the enlightening discussion! Lots in here to chew on.

For context this is primarily for an hour-long live radio broadcast which is also filmed and edited for video after the fact.

We used the setup again last week and I tried putting some isoacoustics isolation pucks we had on hand underneath the stand legs once we had found it's final placement. This seemed to help somewhat and did tame the big thumps below 50hz but is not nearly enough to solve the issue. The pucks also caused a worrying amount of wobble from the stand.

We observed that the floor in this space seems to be a sprung dancefloor which might be responsible for the extent of the issue in the first place. The movement of a standing violinist 10-12 feet from the stand caused visible wobble of the stand itself when it was on the pucks and there were certain areas of the floor that coupled to the stand more than others.

I had looked at the largest Rycote invision mount, but the coles by itself is 1080g coupled with the brass stand/xlr adapters also making quite a bit over the 900g max rating of the USM-VB. I would be worried about droop. It might be worth trying though if other approaches fail.

I have a few things to try now:

One is suspending the whole blumlein bar/mic package with some large diameter elastic cord, similar to the setup Roger posted below.

The second is to weigh the mic/bar/stand setup and order some sorbothane pads that are the proper size for that weight. I may add some sandbags hung low on the stand crossbars, increasing overall mass and lowering the center of gravity to address the wobble. In another thread I came across this weight calculator for speaker decoupling with sorbothane hemispheres:
https://www.isolateit.com/pages/speaker-decoupling

We also have available some very heavy steel lighting stands. I will try hard-mounting the mic bar to one of these and see if the mass helps at all.

I have been using RX7 to clean up the recordings and have found that the de-plosive module can work very well for this once adjusted properly. For some material a simple low cut is also sufficient but for Piano this is not workable as the vibration noise can reach up to 100hz, far into the fundamental of the instrument.

I will update this thread with my progress. Thanks again for all the responses!

-Matt
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