Jump to content
Why become a member? Read more... ×
Basschat Podcast: Episode 2 Read more... ×
Skol303

DIY Acoustic Panels

Recommended Posts

4 hours ago, Skol303 said:

I'm still tempted to get a sub... my monitors are great down to about 40Hz (exceptionally flat), but I don't have much going on below that. However, it's a small room so I'll need to be careful not to add loads of new mode problems.

I'm going to audition one and check; hopefully this week in fact!

that way madness lies, I warn you ;)

 

Share this post


Link to post
Share on other sites
7 hours ago, Skol303 said:

...my monitors are great down to about 40Hz (exceptionally flat), but I don't have much going on below that...

Is there really that much 'going on' below 40Hz that needs such 'flatness'..? o.O

Share this post


Link to post
Share on other sites
26 minutes ago, Dad3353 said:

Is there really that much 'going on' below 40Hz that needs such 'flatness'..? o.O

 

25 minutes ago, Mornats said:

I usually start my high pass filter at around 40hz so wondered the same.

Well you want to be able to hear the bad stuff that might be going on down there.

People tend to forget that 20 to 40Hz is an entire octave (like 10KHz to 20KHz is only one octave).

If your monitors can't do that then who knows what rubbish low end energy you might be chucking out!

Share this post


Link to post
Share on other sites
7 minutes ago, 51m0n said:

...If your monitors can't do that then who knows what rubbish low end energy you might be chucking out!

I took it to read as a lack of linearity rather than dead silence under the 40Hz threshold. It's audible (on good systems...), but does it have to be that flat, was my concern. Any dross will be heard, but slightly attenuated. Is there that much going on that it needs to be linear down to 20Hz (or lower...)..? If the stuff down there is that bad it'll be heard, won't it..?

Share this post


Link to post
Share on other sites
17 minutes ago, Dad3353 said:

I took it to read as a lack of linearity rather than dead silence under the 40Hz threshold. It's audible (on good systems...), but does it have to be that flat, was my concern. Any dross will be heard, but slightly attenuated. Is there that much going on that it needs to be linear down to 20Hz (or lower...)..? If the stuff down there is that bad it'll be heard, won't it..?

Well probably not.

Your ears dont really do sub 40Hz very well, Fletcher-Munsen curves and all that.

So given we struggle to hear that low anyway, if your mains are attenuating that low by a further 6 to 9dB (not unusual) then you have pretty much no chance of telling if there is anything there at all.

Now in a mix situation this is not such a huge deal.

But when you are mastering it really does. Anywhere you can get rid of garbage you should. Not only is it wasted energy but its wasted bits and that equates to less apparent level. Now I am by no means an advocate for the loudness wars thing but if it taught mastering engineers anything it was stow all that rubbish.

So you say, big deal, hi-pass filter sorted. Yeah but sometimes what is down there is real weight thats good, in the bass maybe, and losing that makes the mix weak, but the kick is just phat tubby lard as well so now you need to set up a multiband compressor limiter situation to deal with this. And that is when you'll be all kinds of happy that your monitors can give you some definition and decent clues that deep....

 

Share this post


Link to post
Share on other sites
5 minutes ago, 51m0n said:

Well probably not...

OK, I'll bow to all that, in such a context. I've no issue with a 'pro' studio set-up; the 'diminishing returns' make it largely impracticable for Humans, though, especially in a domestic environment. I'm much more deaf than any of that, anyway, at my age, so... :$

  • Like 1

Share this post


Link to post
Share on other sites
49 minutes ago, 51m0n said:

 

Well you want to be able to hear the bad stuff that might be going on down there.

People tend to forget that 20 to 40Hz is an entire octave (like 10KHz to 20KHz is only one octave).

If your monitors can't do that then who knows what rubbish low end energy you might be chucking out!

That'll be a job for my M50x cans and Sonarworks then :) 

Share this post


Link to post
Share on other sites
Posted (edited)
3 hours ago, Dad3353 said:

Is there really that much 'going on' below 40Hz that needs such 'flatness'..? o.O

Not always... but sometimes certainly yes. And when there is, you REALLY want to know about it.

For context bear in mind that:

1. I produce/remix a lot of electronic dance music and hip hop (aka “bass music”); and so every ounce of low end insight is useful to me, whether the notes are felt or heard. Especially when producing music to be played over large sound systems in nightclubs, some of which are very capable of reproducing bass down to 20-30Hz (sufficient to rattle the optics behind the bar, as I once witnessed during an LFO gig in Sheffield!). Headphones can only go so far in terms of referencing sub 40Hz; to get a true picture you need to move some air.

2. Subwoofers aren’t just about benefiting the lowest of the low frequencies. Using a sub in a 2.1 set up means that your regular monitors don’t need to work so hard; and evidence shows that can add clarity. Depending on where you set the crossover,  a sub also has the potential to help even out the low end up to 100-150hz: filling in some of the nulls (whilst creating peaks that can be corrected by EQ).

3. My room is well treated - pretty much as far as possible for a domestic room. So although the space is small, it’s relatively ‘sub-friendly’.

4. I’m a perfectionist and unabashed Gearslut :D

...all that said, subs are notoriously tricky to set up and can cause more problems than they solve (as rightly mentioned by Si above). Hence I’m going to demo one before committing to a purchase - noting point 4 above often requires a willpower of steel!

Edited by Skol303
  • Like 1

Share this post


Link to post
Share on other sites
On 15/04/2018 at 23:09, 51m0n said:

I hate subs.

They are nightmarish to get right.

If they arent right or you get a skewed mix you are always left thinking "Is it the sub set up?".

Forgot to mention... totally agree with this, but if you have a suitable mic and a copy of REW (free) or FuzzMeasure (what I use) then you can use measurements to supplement your ears when setting up a sub, thus removing some of the guesswork and uncertainty.

You probably know this, but for everyone else what I mean is:

  1. Take measurements to find the optimum location, by placing the sub at the listening spot and then moving the mic around the room whilst measuring frequency sweeps. Best mic position = best sub position. A kind of high-tech version of the "subwoofer crawl".
  2. Take measurements to help set the volume/level of the sub, by tweaking the gain until the low end frequency response and decay time are as flat as possible.

And of course using your ears! :)

I have a sub arriving sometime this week for demo'ing, so I'll test it out and report back here...

(PS: I might move these posts to a separate thread on subwoofers).

Share this post


Link to post
Share on other sites
5 hours ago, Skol303 said:

Forgot to mention... totally agree with this, but if you have a suitable mic and a copy of REW (free) or FuzzMeasure (what I use) then you can use measurements to supplement your ears when setting up a sub, thus removing some of the guesswork and uncertainty.

You probably know this, but for everyone else what I mean is:

  1. Take measurements to find the optimum location, by placing the sub at the listening spot and then moving the mic around the room whilst measuring frequency sweeps. Best mic position = best sub position. A kind of high-tech version of the "subwoofer crawl".
  2. Take measurements to help set the volume/level of the sub, by tweaking the gain until the low end frequency response and decay time are as flat as possible.

And of course using your ears! :)

I have a sub arriving sometime this week for demo'ing, so I'll test it out and report back here...

(PS: I might move these posts to a separate thread on subwoofers).

Yep all sounds great, but the problem with subs is time alignment with your mains around the crossover point. The whole idea that a sub can go more or less anywhere and sound great is misleading at best, it must also be the same distance from both mains (or they will skew, you will get comb filtering and other weirdness etc etc), and any wall reflections need to be taken into consideration. Eventually you find there may be nowhere where your sub doesn't do something funny to the sound in the area where you mains produce something (not enough) and the sub top end.

It can be done, but it is very difficult to do (very very very difficult) even with software, and IME you're better off getting full range speakers to do the job and just take all that guess work out of it :)

  • Like 1

Share this post


Link to post
Share on other sites
16 hours ago, 51m0n said:

It can be done, but it is very difficult to do (very very very difficult) even with software, and IME you're better off getting full range speakers to do the job and just take all that guess work out of it :)

You're no doubt right Si, but a combination of rampant GAS and curiosity (but mostly GAS) has got the better of me on this one :D

As it happens the sub I'm demo-ing arrived yesterday afternoon. Haven't had chance to properly set it up yet, but as an initial test I've placed it between my main monitors (up against the front wall) and just to one side, to avoid the centre room mode. So far I've only set the gain by ear, but I took a quick frequency measurement and to be honest it looks surprisingly promising... observations:

  • It's helped to fill in much of the gnarly dip I had around 70Hz (by +5-6 dB, possibly more)
  • It’s showing a very useful response down to 30Hz, where it then tails off (but still giving me around +10-15 dB at 20Hz compared to what I had previously... not that I can actually hear it!)
  • Above 70Hz the frequency response is pretty much identical to that produced by my main monitors alone (I currently have the crossover set at 60Hz).
  • There's a noticeable boost in the low end, as you'd expect, but I could level that out with DSP software.
  • No signs of comb filtering that I could spot from the frequency graph; but I need to take some proper measurements and also check decay times, etc.

So hmmm...definitely not helping my GAS! But the initial signs are that a sub may actually be of benefit in my room. Especially because I don't have capacity to install main monitors any larger than those I currently have.

I'm hoping to do some proper tests at the weekend and will report back, in case the info is useful to anyone here who might also suffer from sub GAS at some point.

  • Like 1

Share this post


Link to post
Share on other sites
5 hours ago, Skol303 said:

You're no doubt right Si, but a combination of rampant GAS and curiosity (but mostly GAS) has got the better of me on this one :D

That's it mate - you're soooo screwed :D

  • Haha 1

Share this post


Link to post
Share on other sites

Back to far more slap-dash matters...

In my attempts to sneak whatever treatment I can into my room, I have a cheap foam trap in the corner behind the TV. The materials I'm planning to buy for absorbers will leave me with enough left over to build a proper superchunk to place back there. The idea is to build it just high enough to be barely visible over the top of the TV, which, on a sturdy wooden TV stand/cupboard, straddles the corner.

As before, I think I know the answer, but filling the void behind this arrangement will still be of benefit, despite not being much use as a broadband absorber, due to the higher frequencies reflecting off the cupboard and TV itself, won't it?

Share this post


Link to post
Share on other sites

Or to put it more simply, a superchunk, covering the lower 50% of the wall, but behind this is still going to be effective, isnt it?

IMG_20180420_130130.thumb.jpg.33c11c0f1c5d92392ab096030aa59622.jpg

Share this post


Link to post
Share on other sites
Posted (edited)
8 hours ago, Jus Lukin said:

...a superchunk, covering the lower 50% of the wall, but behind this is still going to be effective, isnt it?

Yeah sorry for the dalliance into subwoofers! :D (I may yet move that to a thread of its own).

To answer your question, yes, a superchunk covering the lower section of wall will certainly be of some benefit... but it will be a lot more effective if you build it to the full height of the room. That would not only provide a greater surface area/ amount of treatment, but also help to deal with that upper corner, where bass frequencies tend generate the most pressure (low frequency energy).

So a full height superchunk would be my recommendation - after all, it’s otherwise dead space so you might as we do something useful with it.

But if you want to restrict the height for aesthetic reasons, that’s your call to make, of course. Any acoustic treatment is nearly always better than none :)

PS: i assume you’re planning on adding other treatment elsewhere in the room?

Edited by Skol303

Share this post


Link to post
Share on other sites

Dally away, dear boy!

It's a very compromised situation as far as treatment is concerned as we are in a one bedroom flat- were it up to me the room would be done out as a studio full-stop, but like a fool I've chosen to share the place with a girl! To be fair, I already encroach a fair deal with my stuff all over the place, so I'm trying to get an effective minimum, with the attitude that anything is better than nothing.

The full plan is the half-height chunk hidden behind the TV, diagonally across the room I'll put another on top of a cupboad which will fill the top tri-corner, and then behind my desk (and monitors) I'll have a couple of large panels which will cover head-height either sitting or standing for a large percentage of the space. The panels will only be 2" deep so will probably be effective down to 500hz or so. Hopefully the traps will go some small way to controlling things below there.

I don't do any professional mixing, so this is just to flatten response and reduce decay times as best I can in a domestic space, for my own pleasure really. Not least, I hope it will reduce the 3D swirling effect from the traffic noise outside, as in this nice weather it doesn't seem to be coming from the open window so much as pressing in from all sides!

Definitely a bit of a vanity project though, being honest.

Share this post


Link to post
Share on other sites
Posted (edited)

^ “Every little helps” when it comes to acoustic treatment, for sure. And in a shared/multipurpose space there will always be compromises... which by the sound of things you’re making the most of. Good approach.

A few ideas and pointers:

1) You could try inserting a thin sheet of ply board into your bass traps - ideally 4-6mm thick, fixed loosely in the front face of the panel so that it can vibrate. This ‘membrane’ will help to further dampen the lowest frequencies and will also reflect some of the mids/highs back into the room. Peg board (with holes) has traditionally been used in studios for this purpose.

2) Don’t over-do it with the 2” panels. If you disproportionally over-dampen the mids/highs you will, in effect, ‘boost’ the bass, making the room sound boomy.

3) Use a more dense material for the 2” panels: Knauf RS60 (48kg/m3) as a minimum; possibly even up to 100kg/m3 density to be effective at that thickness. The fluffy Knauf DriTherm 37 is only really suitable for panels with a minimum thickness of 4” and ideally 8” or more.

Let us know how you get on! And rest assured that anyone who lets you install acoustic treatment in your shared living space is a good catch :) 

Edited by Skol303

Share this post


Link to post
Share on other sites
8 hours ago, Skol303 said:

Let us know how you get on! And rest assured that anyone who lets you install acoustic treatment in your shared living space is a good catch :) 

Indeed, over 20 years since we first met! Of course that's plenty of time for other benefits to have run a little dry. Letting me stick my panels in her living room is about the best can expect these days! :D

Thanks for the tips, couple of questions, of course!

9 hours ago, Skol303 said:

1) You could try inserting a very thin sheet of ply board into your bass traps - ideally 2mm thick or less, fixed loosely in the front face of the panel so that it can vibrate. This ‘membrane’ will help to further dampen the lowest frequencies and will also reflect some of the mids/highs back into the room. Peg board (with holes) has traditionally been used in studios for this purpose.

As for the dampening of the lows, would this require any tuning, as in a Helmholtz type thing, or can it be said that the addition panel will fairly broadly assist in controlling that low energy?

9 hours ago, Skol303 said:

2) Don’t over-do it with the 2” panels. If you disproportionally over-dampen the mids/highs you will, in effect, ‘boost’ the bass, making the room sound boomy.

I'm thinking I'll be OK here- I'll essentially be looking to cover 1.2m x 2.4m of wall with the 2" panels, leaving the ceiling and two walls plain, and one wall with two big windows with thin curtains. I may look into putting half the panels on the rear wall; I could potentially make those 4", and aesthetics would mean using a material which isn't so acoustically transparent and therefore more reflective. Would be hard to place everything properly offset though- more chance of spots where standing waves could occur.

9 hours ago, Skol303 said:

3) Use a more dense material for the 2” panels: Knauf RS60 (48kg/m3) as a minimum; possibly even up to 100kg/m3 density to be effective at that thickness. The fluffy Knauf DriTherm 37 is only really suitable for panels with a minimum thickness of 4” and ideally 8” or more.

Initially I was looking at Rockwool RW3 (which may have changed it's name now) at 60kg/m3. The easiest to get hold of seems to be the Rockwool Sound Insulation Board which is surprisingly hard to find proper specs for, but I think it may be the same as the RW45 at 45kg. I'll have another check for availability of that RW3...

Share this post


Link to post
Share on other sites
Posted (edited)
14 hours ago, Jus Lukin said:

Letting me stick my panels in her living room is about the best can expect these days!

I think that's the first acoustic-treatment-related euphemism I've ever heard! xD

14 hours ago, Jus Lukin said:

As for the dampening of the lows, would this require any tuning, as in a Helmholtz type thing, or can it be said that the addition panel will fairly broadly assist in controlling that low energy?

Yes, membrane traps certainly can require tuning, because the thickness of the membrane will determine the target frequency (the peak of the 'bell curve', if you think of it like an EQ).

I've never built a membrane trap myself, but have read up on them whilst nerding around on the subject. I've double-checked in replying to your question, and contrary to my advice above (which I'll edit to correct), the membrane should be between 4-6mm thick for what you're aiming to achieve (not <2mm as I'd originally suggested). For example: 6mm plywood will target ~90Hz. The membrane needs to be either:

  • Installed fairly loosely on the front of the panel (behind the fabric), so that it can move back and forth like a piston. I'd recommend a minimum number of panels pins, trying to avoid hammering them all the way in.
  • Perforated - e.g. peg board - whereby the perforations help the membrane to flex.

That said, the BBC used to use hardboard without holes as a damped membrane on their Modular LF Absorbers, so there appears to be several ways to approach it.

My own choice would be to use a sheet of peg board, fitted to the front of the trap (behind the fabric). I'm fairly sure that peg board comes in either 3.5mm or 6mm thickness, either of which would be suitable.

14 hours ago, Jus Lukin said:

I'm thinking I'll be OK here- I'll essentially be looking to cover 1.2m x 2.4m of wall with the 2" panels, leaving the ceiling and two walls plain, and one wall with two big windows with thin curtains. I may look into putting half the panels on the rear wall; I could potentially make those 4", and aesthetics would mean using a material which isn't so acoustically transparent and therefore more reflective.

Thicker panels on the rear wall is definitely a good idea, if space allows. You otherwise won't suffer any over-damping with the coverage of 2" panels that you mention. The window is essentially a 'free' bass trap.

14 hours ago, Jus Lukin said:

Initially I was looking at Rockwool RW3 (which may have changed it's name now) at 60kg/m3. The easiest to get hold of seems to be the Rockwool Sound Insulation Board which is surprisingly hard to find proper specs for, but I think it may be the same as the RW45 at 45kg. I'll have another check for availability of that RW3...

RW3 would be a good choice for the 2" and 4" panels. RW45 would also be ok, but you don't want to go any less dense than 45kg/m3 at those thicknesses.

Edited by Skol303

Share this post


Link to post
Share on other sites
2 hours ago, Skol303 said:

RW3 would be a good choice for the 2" and 4" panels. RW45 would also be ok, but you don't want to go any less dense than 45kg/m3 at those thicknesses.

Good to know, thanks. I've been amazed at how hard it is to find proper details on insulation products, and more so how awkward they are to actually buy. Finding it on the internet is fiddly, certainly without delivery costs which aren't greater than the price of the product itself. I think I will put my lazy streak aside and pop into Travis Perkins to order some RS100. I'm sure they'll be able to get some in which I can just collect!

Share this post


Link to post
Share on other sites
On 23/04/2018 at 13:02, Jus Lukin said:

I've been amazed at how hard it is to find proper details on insulation products, and more so how awkward they are to actually buy.

Yep, I share your pain! I've spent literally hours trawling online trying to find data on the density, flow resistivity, etc, of certain products to no avail.

Best resource I've found is the page on Bob Golds' website here:

https://www.bobgolds.com/AbsorptionCoefficients.htm

With some 'artistic licence' you can find equivalent products and extrapolate approximate data. Worth a look.

Share this post


Link to post
Share on other sites

Thanks for the links, I've done a fair bit of roughing it out based on Bob Golds data. Couldn't help but notice even he can't find specs for the RWA45!

I'd not seen the BBC stuff. You do realise I'm now going to have read my way through all of that, don't you 51m0n? xD

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

  • Similar Content

    • By Clint
      Eden CaliforniWAH Bass pedal in mint condition and boxed with 15V Power Supply. Great pedal but only had it out the box a few times and never gigged time to move it on! 
      Would swap for TC Elcetronic Mini Vortex 
       


    • By BCH
      SOLD
      This is my stunning Enfield Cannon 4 string bass with Super 8 pickup & case. I was very lucky to buy this new in 2010, its in excellent condition & has been kept in a smoke free studio. It is set up by Auden guitars.
      Martin Simms designed this unique bass in 2008, the quality of components, build & finish is of the highest quality. Martin has finished 3 of my basses over the years. I view him as one of the top bass luthiers. The Cannon model is top of the range custom built, this one is stunning to look at blending from the sunburst finish front to the blue back...The top is made from English Sycamore that came from Wales. It was from a batch Martin got from a furniture maker who had the wood for over 50 years in his workshop and when he retired sold it on and we were lucky enough to receive a small quantity.   It is fab to play and the sound pallet is vast because of the Super 8 pickup design partnership with John East...any question please contact (  have some 2008+ reviews)..this is a wold class bass & a serious investment (I have inc' the price list which is now £5700), so come and try...this is why its a cash on collection   Some links http://www.enfieldguitars.com/cannon.html
       
      https://www.youtube.com/watch?v=JBujWmzlUrw
       
      https://www.youtube.com/watch?v=r0TsJ8osYoc
       
      https://www.youtube.com/watch?v=Zx1QIXoALQA
       
      http://www.bassplayer.com/basses/1165/enfield-basses/25905
       
      From Enfield web  Our Enfield Cannon was the first model we launched back in 2008 to showcase our unique Super 8 pickup. Still our flagship model they are built to the highest standard using only our best hand selected timbers. All cannon basses are built to order and are available in either 4, 5 or 6 string models.
      The cannon has been specially designed not only for the pro player but for anyone that seeks the ultimate in sound from their bass. With our Super 8 pickup and it's eight individual coil's along with our uniquely designed pre-amp built to our specifications by the renowned 'John East' ( J-Retro fame ) the cannon is perfect for any gigging or studio situation.
      Cannon Specification's
      Tone chambered body with bespoke hardware designed and produced by Enfield Guitars.
      Standard quarter inch jack and a Balanced XLR output.
      Maple neck with dual action truss rod and 25 med/jumbo frets fitted with custom prepared 'Hipshot' tuners.
      Nut Width's
      4 String Cannon = 44mm








      Bass Player Review 2 PDF.pdf
      Enfield instructions page 3.pdf
      Enfield instructions page1.pdf
      Enfield instructions page2.pdf
      Enfield review 3.pdf
      Enfield review 4.pdf
      EnfieldReview1.pdf
    • By erik.leroy
      Goodevening everyone,
      I don't know what to do: All my bass plugins sound awfull in reaper (I have a lenovo laptop). I've tried dozens of bass plugins and they sound, wel... crap. I recently downloaded Ample bass P Lite II, it sounded great on a youtube tutorial but on my laptop it sounds awfull. I spent hours trying to fix it, but I'm no daw wizzkid (i'm a historian...).  Is it my hardware? Can someone please please help me? I'll mow your lawn.
       
      Erik
    • By Touchwood
      I am selling this for the family of a friend who has recently passed away. I have got  permission from the Admin (ped) to place this ad.
      1987 Mk1Custom
      Brazilian Mahogany core
      Canadian 'Birdseye' Maple faces
      Indian Rosewood F/Board
      Full Flightcase
      Slight crack to front facing (cosmetic only)
      This bass was made by Ian Waller for a friend who has recently passed away and has had one owner from new.
      This is the first EVER Wal with a lacquer finish and was the start of Wal offering a lacquer finish option.
      Collection from Kendal, UK, or will ship for cost of shipping.








    • By nick-harrison
      For sale is a 2016 Fender american precision deluxe (the previous style to the newest precision bass with the larger bridge). I'm asking for £750 and no trades as I have no need for another bass.
      Hence the sale of this one.
      In perfect working order, although, unfortunately minor damage to the paintwork. Small chip in belly cut. And surface scuff near arm radius.
      Specs are: 
      Olympic White body with black pickguard
      Active/passive flick switch
      Fender N3 jazz pickup and a split cool precision pickup 
      Rose wood fretboard and maple neck
      Controls are : volume. Pick up blend. Treble&bass stack knob. Mid sweep & boost cut stack knob. 
      I'm not entirely comfortable sending this bass via courier as I have endured problems with this before.
      I live in Rugby and am open to people collecting the bass or alternatively arrange to deliver the bass personally to you (within a reasonable distance) or possible even meeting halfway. 
       
       










×