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duvets or mic screens

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duvets or mic screens

Postby SableTones » Tue Jan 03, 2012 9:23 am

hi.....if i have endless patience, lots of gaffer and string...and loads of duvets, do i really neded to invest in screens and reflection filters etc for my home recording......or in a small hall even, where visuals is not important????
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Re: duvets or mic screens

Postby The Elf » Tue Jan 03, 2012 9:50 am

IMO - no you don't.

And I'd go as far as to say that a bunch of old duvets can do a better job than 'pro' screens anyway.
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Re: duvets or mic screens

Postby shufflebeat » Tue Jan 03, 2012 9:57 am

Agreed.

I have a reflexion filter which does it's job well but it only does (in my setup) what the duvet was doing. It still needs support from heavy curtains and further duvetech behind the mic.
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Re: duvets or mic screens

Postby Hugh Robjohns » Tue Jan 03, 2012 11:41 am

If you think about the way a (cardioid) mic works, it becomes very obvious that a broadband absorber (eg. duvet) placed in front of the mic but behind the performer (and ideally, extending around the sides too) will have a significantly greater effect in reducing unwanted room reflections than a 'filter' placed behind the mic.

Both are useful, but I'd rig the duvet before worrying about a filter.

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Re: duvets or mic screens

Postby John Willett » Tue Jan 03, 2012 12:19 pm

Hugh Robjohns wrote:If you think about the way a (cardioid) mic works, it becomes very obvious that a broadband absorber (eg. duvet) placed in front of the mic but behind the performer (and ideally, extending around the sides too) will have a significantly greater effect in reducing unwanted room reflections than a 'filter' placed behind the mic.

Both are useful, but I'd rig the duvet before worrying about a filter.

hugh

I agree with Hugh on this.

I use an absorber behind the singer, in front of the mic.. This minimises room reflections bouncing back off a hard surface into the mic.. It works very well.

Personally, I can't really see the point of these reflection filters as they are behind the mic. where the mic. is least sensitive anyway.
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Re: duvets or mic screens

Postby alexis » Tue Jan 03, 2012 12:35 pm

John Willett wrote:
Hugh Robjohns wrote:If you think about the way a (cardioid) mic works, it becomes very obvious that a broadband absorber (eg. duvet) placed in front of the mic but behind the performer (and ideally, extending around the sides too) will have a significantly greater effect in reducing unwanted room reflections than a 'filter' placed behind the mic.

Both are useful, but I'd rig the duvet before worrying about a filter.

hugh

I agree with Hugh on this.

I use an absorber behind the singer, in front of the mic.. This minimises room reflections bouncing back off a hard surface into the mic.. It works very well.

Personally, I can't really see the point of these reflection filters as they are behind the mic. where the mic. is least sensitive anyway.

Is the idea that it prevents the sound from going beyond the mic and then reflecting off the wall facing the singer, to then rattle around in the room?
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Re: duvets or mic screens

Postby ryan mead » Tue Jan 03, 2012 2:45 pm

shufflebeat wrote: duvetech
Awesome neologism! Did you coin this, or am I just not in touch with the kids these days?
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Re: duvets or mic screens

Postby Hugh Robjohns » Tue Jan 03, 2012 2:51 pm

alexis wrote: Is the idea that it prevents the sound from going beyond the mic and then reflecting off the wall facing the singer, to then rattle around in the room?

They certainly absorb some of the sound and reduce the amount of energy going out into the room, but not a particularly significant amount in my experience. The main benefit is in preventing some of those reflections reaching the rear and rear sides of the mic -- and in the case of a cardioid mic, those regions are still surprisingly sensitive. ONly the absolute 180 degree rear null offers any substantial 'deafness'. Most cardioids are only 6dB down at the 90 degree point, and rarely more than 15dB down across much of the rear.

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Re: duvets or mic screens

Postby Folderol » Tue Jan 03, 2012 7:18 pm

I find a duvet works well for me. The only downside is that it doesn't improve my singing.

Besides, you ever tried using a mic screen as a makeshift duvet!
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Re: duvets or mic screens

Postby ConcertinaChap » Tue Jan 03, 2012 8:59 pm

I've got a duvet permanently fixed hanging about 3 inches from the wall. It's great for storing the mic screen behind it that came for free with a mic.

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Re: duvets or mic screens

Postby alexis » Wed Jan 04, 2012 12:01 am

Hugh Robjohns wrote:
alexis wrote: Is the idea that it prevents the sound from going beyond the mic and then reflecting off the wall facing the singer, to then rattle around in the room?

They certainly absorb some of the sound and reduce the amount of energy going out into the room, but not a particularly significant amount in my experience. The main benefit is in preventing some of those reflections reaching the rear and rear sides of the mic -- and in the case of a cardioid mic, those regions are still surprisingly sensitive. ONly the absolute 180 degree rear null offers any substantial 'deafness'. Most cardioids are only 6dB down at the 90 degree point, and rarely more than 15dB down across much of the rear.

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Thank you for that, Hugh!

Being a newbie in many more ways than not, I went to my AT 4033a spec sheet ( http://www.vadlyd.dk/addinfo/AT4033a.pdf ), and saw that it was labelled "cardioid". But on inspecting the polar diagram, it looked like the best place for "deafness" was at around -45 degree "behind the horizontal", rather than the "180 degree rear" (where it looked like it was fairly sensitive, especially at 8kHz).


Can you please help me figure out where my interpretation of the polar diagram is wrong, based on your statement above?

Thanks so much, as always!
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Re: duvets or mic screens

Postby James Perrett » Wed Jan 04, 2012 9:53 am

alexis wrote:
Can you please help me figure out where my interpretation of the polar diagram is wrong, based on your statement above?

All the plots apart from the 8kHz one look like cardioid to me. It is only the 8kHz plot that deviates from the classic cardioid shape and that's probably down to the size of the diaphragm which starts to play a significant part in the mic's characteristics at high frequencies.

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Re: duvets or mic screens

Postby Mike Stranks » Wed Jan 04, 2012 10:09 am

Re: Alexis.

The pick-up pattern of very many (all?) cardioid (and their derivatives hyper, super etc.) microphones varies with frequency. Some manufacturers cheat and only show the 1kHz pattern.

In this case AT have shown the pick-up pattern at various frequencies. As James Perrett has said, the pattern is cardiod, but moving to hyper-cardioid at higher frequencies. Not unusual.

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Re: duvets or mic screens

Postby Hugh Robjohns » Wed Jan 04, 2012 10:28 am

James and TDC have already explained, but just to add, very few microphones are perfect in all regards. Few have perfectly flat frequency responses, for example, and few manage perfectly consistent (in terms of their shape versus frequency) polar patterns either.

Most large diaphragm capacitor mics like the AT4033 tend to become more omnidirectional at very low frequencies, and more hyper-cardioid at very high frequencies -- and that's what you're seeing in those manufacturer plots.

These variations in polar response with frequency is what gives rise to the colouration that affects off-axis sounds, because some parts of the spectrum are captured with greater or less sensitivity than others.

The 4033 is actually a pretty good cardioid mic, but it does develop a bit of a hyper-cardioid tail at the high end, as you can see.

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Re: duvets or mic screens

Postby alexis » Wed Jan 04, 2012 2:52 pm

Thank you James, Theo-DC and Hugh!

I have to say that I cannot distinguish the line representing the 100Hz pick-up pattern on that polar diagram, to follow Hugh's comment that it behaves like an Omni mic at low frequencies. But the bigger points in all your comments are well-taken and much appreciated!
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Re: duvets or mic screens

Postby shufflebeat » Wed Jan 04, 2012 4:03 pm

ryan mead wrote:
shufflebeat wrote: duvetech
Awesome neologism! Did you coin this, or am I just not in touch with the kids these days?

Ha, I think I just thought of it but it sounds like something somebody should have said before so they probably have.

I think it's worth pointing out that the reflexion filter is not only effective in conjunction with other bits and pieces but does the job quite elegantly. Duvets are great but they look a bit too much like duvets.
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Re: duvets or mic screens

Postby Fran Guidry » Sun Jan 08, 2012 12:12 am

Hugh Robjohns wrote:If you think about the way a (cardioid) mic works, it becomes very obvious that a broadband absorber (eg. duvet) placed in front of the mic but behind the performer (and ideally, extending around the sides too) will have a significantly greater effect in reducing unwanted room reflections than a 'filter' placed behind the mic.

Both are useful, but I'd rig the duvet before worrying about a filter.

hugh


It takes some nerve for me to do this, but I'm going disagree. I've experimented with two OC703 panels in different locations to reduce reflections in a small room. Placing them behind the performer had almost no effect. Placing them behind the mic was dramatically effective.

As you say in one of the other posts in this thread, the cardioid pattern only reduces, but far from eliminates, sensitivity behind the mic, so defending the rear of the mic gives real benefit.

Here's a bit of a demo, if you skip to the end of the clip it cuts back and forth between the paneled and non-paneled samples: http://www.youtube.com/watch?v=0mPR0q1KzqQ

Perhaps I'm going beyond your suggestion, Hugh, since you're comparing a fairly large duvet to a pointlessly small Reflexion or similar. I wouldn't even consider one of those worth using. But absorption behind the mic (actually behind an XY-120 pair) seemed to have a very large impact in my evaluations.

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Re: duvets or mic screens

Postby turbodave » Sun Jan 08, 2012 1:27 am

Fran Guidry wrote:
Hugh Robjohns wrote:If you think about the way a (cardioid) mic works, it becomes very obvious that a broadband absorber (eg. duvet) placed in front of the mic but behind the performer (and ideally, extending around the sides too) will have a significantly greater effect in reducing unwanted room reflections than a 'filter' placed behind the mic.

Both are useful, but I'd rig the duvet before worrying about a filter.

hugh

It takes some nerve for me to do this, but I'm going disagree. I've experimented with two OC703 panels in different locations to reduce reflections in a small room. Placing them behind the performer had almost no effect. Placing them behind the mic was dramatically effective.


As you say in one of the other posts in this thread, the cardioid pattern only reduces, but far from eliminates, sensitivity behind the mic, so defending the rear of the mic gives real benefit.

Here's a bit of a demo, if you skip to the end of the clip it cuts back and forth between the paneled and non-paneled samples: http://www.youtube.com/watch?v=0mPR0q1KzqQ

Perhaps I'm going beyond your suggestion, Hugh, since you're comparing a fairly large duvet to a pointlessly small Reflexion or similar. I wouldn't even consider one of those worth using. But absorption behind the mic (actually behind an XY-120 pair) seemed to have a very large impact in my evaluations.

Fran

Hi, I think the issue may be with the term effect. The fact that you hear an effect possibly means that the absorption behind the mic is changing the sound of the mic rather than creating a non reflective environment. Dave
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Re: duvets or mic screens

Postby Hugh Robjohns » Sun Jan 08, 2012 2:39 pm

Fran Guidry wrote:It takes some nerve for me to do this, but I'm going disagree.

Have no fear -- I'm always up for a discussion on things, and different situations often result in different results. And your situation is, indeed, very different to the one I was describing.

I've experimented with two OC703 panels in different locations to reduce reflections in a small room. Placing them behind the performer had almost no effect. Placing them behind the mic was dramatically effective.

Yes...but you're working with a stereo mic and one which is probably quite close to back-back cardioids -- so far more sensitive to the sides than a single mono cardioid would be. You're also using relatively large panels very close to the mics.

Which means that I'd be surprised if you got anything other than the results you described: putting the panels behind you to soak up reflections from the back wall will have an insignificant effect given the huge amount of room sound that the mics will capture from the sides and rear of the stereo mic array.

Essentially, I was describing apples and you're using oranges!

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Re: duvets or mic screens

Postby Tomás Mulcahy » Sun Jan 08, 2012 9:51 pm

Fran Guidry wrote: an XY-120 pair
Hi Fran, you'll find a great diagram of that pickup pattern here:
http://www.sengpielaudio.com/Visualization-EBS-E.htm
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Re: duvets or mic screens

Postby Fran Guidry » Mon Jan 09, 2012 12:06 am

Tomás Mulcahy wrote:
Fran Guidry wrote: an XY-120 pair
Hi Fran, you'll find a great diagram of that pickup pattern here:
http://www.sengpielaudio.com/Visualization-EBS-E.htm

Thanks, Tomas. Way cool!

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Re: duvets or mic screens

Postby Fran Guidry » Mon Jan 09, 2012 12:08 am

Hugh Robjohns wrote:...
Yes...but you're working with a stereo mic and one which is probably quite close to back-back cardioids -- so far more sensitive to the sides than a single mono cardioid would be. You're also using relatively large panels very close to the mics.

Which means that I'd be surprised if you got anything other than the results you described: putting the panels behind you to soak up reflections from the back wall will have an insignificant effect given the huge amount of room sound that the mics will capture from the sides and rear of the stereo mic array.

Essentially, I was describing apples and you're using oranges!

hugh

Hugh, thanks for the response. I'm in Hawai`i over the holidays http://www.youtube.com/watch?v=WgyD8qaVOTM and won't be able to try this out for a week or so.

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Re: duvets or mic screens

Postby Dilithium » Mon Jan 09, 2012 3:28 pm

Perhaps, a stupid question, but how do you hang the duvets up? They're not the lightest things and don't normally come with pre-fitted eyelets! I'll just buy a couple and use them for this purpose. Doing whatever is necessary, is fine. So...

Nail them to the wall? Use curtain rails and add eyelets to to them. Use some kind of high clothing rail?

Lastly, (and this has the potential to have some serious p***-taking) any TOG rating? :-) The higher the better, I presume.

Thanks,

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Re: duvets or mic screens

Postby Hugh Robjohns » Mon Jan 09, 2012 4:07 pm

Tog rating: yes the higher the better. Use cheap polyester duvets -- expensive down-filled ones don't work as well because the down tends to slump and clump!

Hanging: whatever works for you. Sewing on large eyelets and then hanging from hooks or a curtain rail is a simple solution. Using DIY spring-loaded hand clamps to fix the duvet to a T-bar lighting stsand works well. Hanging the duvet a few inches from the wall is better than having it flat against the wall if you can.
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Re: duvets or mic screens

Postby alexis » Mon Jan 09, 2012 4:45 pm

Hugh Robjohns wrote:Tog rating: yes the higher the better. Use cheap polyester duvets -- expensive down-filled ones don't work as well because the down tends to slump and clump!

Hanging: whatever works for you. Sewing on large eyelets and then hanging from hooks or a curtain rail is a simple solution. Using DIY spring-loaded hand clamps to fix the duvet to a T-bar lighting stsand works well. Hanging the duvet a few inches from the wall is better than having it flat against the wall if you can.

I believe (?) I've read somewhere in the past that singer's back to a corner is best ... is that really important, or is flat gainst the wall OK?

Thanks!
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Re: duvets or mic screens

Postby Hugh Robjohns » Tue Jan 10, 2012 12:49 am

Being close to the corner can exacerbate bass mode problems where the mic essentially develops an unusually pronounced bass boost, often quite a lumpy one too! The advantage is that the duvets stretch out to the sides as well as just the rear, making it more effective at damping room reflections over a wider angle.

Personally, I prefer to rig the thing on a wall rather than the corner, away fromt he wall if the mounting arrangemetns allow, and with the duvte arced around the back of the performer if possible.

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Re: duvets or mic screens

Postby planetnine » Thu Feb 02, 2012 10:26 pm

Dilithium wrote:Perhaps, a stupid question, but how do you hang the duvets up? They're not the lightest things and don't normally come with pre-fitted eyelets! I'll just buy a couple and use them for this purpose. Doing whatever is necessary, is fine. So...

Nail them to the wall? Use curtain rails and add eyelets to to them. Use some kind of high clothing rail?

Lastly, (and this has the potential to have some serious p***-taking) any TOG rating? :-) The higher the better, I presume.

Thanks,

Neil (awaiting comical abuse, followed by useful info)


I use a lighting stand, a lighting 'T'-bar with no lights on it, and four or six "springclips" (market stall traders use them to fasten the tarpaulin onto their stall frames).

We have set up truss in someone's living-rom before, though...


>
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Re: duvets or mic screens

Postby JPH » Fri Feb 03, 2012 11:21 am

sabletones wrote:hi.....if i have endless patience, lots of gaffer and string...and loads of duvets, do i really neded to invest in screens and reflection filters etc for my home recording......or in a small hall even, where visuals is not important????

Well, have recorded perfectly adequate guide vox without the filter, but managed to find a Project Filter at a good price just before Christmas.. so will be combining both duvets and filter for the proper vox to go down in a couple of weeks...

Will let you know what I find!
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Re: duvets or mic screens

Postby Jimmy T » Mon Feb 06, 2012 7:56 am

I find a staple gun is a discreet way to hang duvets.
The holes left by the staples are very small and will disappear with a lick of paint.
Depends on your wall but for wood chip or bubbly paper this method is good. Works well on the ceiling too.
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