Room treatment, taken measurements, what's next?

[jellyjim]

Hello

Time to take room treatment seriously. I've made basic measurements with REW and a miniDSP UMIK-1. Below are the SPL graphs but all the info you could ever need is beyond the link (URL is freaky looking because it's an AWS Amplify instance). Room measurements are D (3.96m) L (5.81m) H (2.72m).

As well as the formidable expertise around these parts, I'll probably take up the various offers of free advice from the companies who sell acoustic panels, hence being so thorough.

My monitors are Genelec 8330a. They are the models with SAM room correction. The measurements were taken with it disabled but otherwise I use it. It's my understanding the SAM technology could still improve upon a treated room but isn't a good substitute for it.

My main concern, beyond the good practice of a treated room, is the low end. No surprises there! If I walk around the room there are very obvious peaks and troughs. What worries me is, judging by ear, I think my listening position may be a peak.

I'm embarking upon a series of projects focused on electronic music, targeted for smaller club PAs (it's actually an art installation but that's for another story). Hence the low end being more important than ever. This includes genres that stretch in to the sub bass range.

My initial questions are:

• From the data provided, is it possible to get a rough idea of how 'good' or 'bad' my room is? That is to say, what is the scale of the task ahead of me? As of now, I don't have enough knowledge of acoustics to make that judgment myself. Is this something I can even tackle myself? There's a budget of around £1,000 for acoustic treatment.

• What are the next steps for educating myself? I'm not entirely ignorant of all the ins and outs but I've very much only just scratched the surface. A single resource would be preferred. Endless YouTube videos can go in one ear and out the other. I have been told that everything you really need to know is in the REW documentation. True?

Finally, on the subject of sub bass, I've been told more than once that I'll almost certainly need a sub. There's a further £1,000 budget for that. The Genelec 7350a (also with SAM) being the obvious choice.

Thanks! Any info much appreciated. Not looking to be spoon fed. Quite excited to finally be taking this aspect of recording seriously!

https://main.dugx4afw9egpp.amplifyapp.com/

[James Perrett]

My first thought is that if you want to get serious about this then you need to think about re-arranging your room so that the acoustics are more symmetrical and you don't have that large piece of furniture next to one of the speakers.

The main area of concern is at the bass end where certain frequencies are missing. The problem is that the missing frequencies are different on each side due to the asymmetry. Both plots show a peak around 500Hz which, from looking at the Genelec website, appears to be a characteristic of your speakers so can probably be ignored. The speakers also show a reduction in output around 2.5kHz when you move off axis which needs to be taken into account. Otherwise, once you get above the bass region, things look reasonably smooth.

My feeling is that if you aren't keen on optimising the room layout then you might be better off judging bass on headphones.

[jellyjim]

Thanks James

Yes I had wondered about the asymmetry and the tall drawers behind the right monitor have always felt wrong. I’m certainly open to moving things about. Would you go so far as to say achieve better symmetry before even considering anything else? It’s the spare room come my day job office space come studio so it’s all up for grabs. What’s preferable? Monitors facing the longer axis or the shorter axis? The obvious choices seem to be the chimney breast (to the left of the listening position) or the bay window to the right, although I’m not sure of the significance of glass behind the monitors. Presumably glass behaves differently to a brick wall in terms of acoustics.

[jellyjim]

And does symmetry include ‘matching obstructions’, so to speak? So the two bookcases are pretty much equal dimensions and density (books). So perhaps lose the tall chest of drawers, bring the studio desk to the right, flush with the door is probably about the centre of the room, and then bring the other bookcase into the left hand alcove (same wall as studio desk), turned to face same direction as studio desk and right hand bookcase.

[James Perrett]

So perhaps lose the tall chest of drawers, bring the studio desk to the right, flush with the door is probably about the centre of the room, and then bring the other bookcase into the left hand alcove (same wall as studio desk), turned to face same direction as studio desk and right hand bookcase.

That would be a good first step. Losing the tall chest of drawers is probably going to gain you the most. Also try raising the monitors higher so that desk reflections become less of an issue - while it may or may not work in your case, this made a big difference to my living room setup.

[Sam Spoons]

You mentioned there being a bass peak at your listening position, my first reaction to that was to suggest moving the listening position (as James says). Ideally the listening position should avoid coinciding with a simple fraction of the room dimensions. IIRC 42% from a wall is the best position to avoid nodes/antinodes.

Accepted wisdom is that having your monitors firing down the long axis of the room is a good idea.

Windows will act, to some extent, as bass traps by allowing bass energy to pass through instead of reflecting it (as a brick or block wall would) so having the speakers facing them or in front of them, in the bay, may help reduce bass nodes.

No domestic room is going to be ideal however well you treat it but my little basement studio sounded so much better after I fitted a few panels and bass traps. Unless you are prepared to pay for a professional to design it you are going to find compromises (above and beyond those imposed by the room).

Small, practical point, can you exchange the bed for a sofabed?

[jellyjim]

You mentioned there being a bass peak at your listening position, my first reaction to that was to suggest moving the listening position (as James says).

Yup, fortunately there's a bank holiday weekend coming up! What's a bank holiday weekend for if it's not for fiddling about with the studio?

Accepted wisdom is that having your monitors firing down the long axis of the room is a good idea.

Yes, I think I knew this but forgot it! Some Googling revealed this was generally preferred and it seemed familiar once I dug in.

Windows will act, to some extent, as bass traps by allowing bass energy to pass through instead of reflecting it (as a brick or block wall would) so having the speakers facing them or in front of them, in the bay, may help reduce bass nodes.

Great

No domestic room is going to be ideal however well you treat it but my little basement studio sounded so much better after I fitted a few panels and bass traps. Unless you are prepared to pay for a professional to design it you are going to find compromises (above and beyond those imposed by the room).

For sure, I'm aiming for improvements rather than perfection, and no there isn't budget for a pro job.

Small, practical point, can you exchange the bed for a sofabed?

That's good idea, thank Sam.

I think the plan then is:
Rearrange room
Bass traps
Remeasure
Then address the remainder of the frequency range

[Hugh Robjohns]

Lots of good advice already given.

But fundamentally, the only way to resolve the lumpy low end is with proper bass traps — as big and as many as you can manage. If you build them across the corners they don't impact the room's usability too much.... (he says... )

Without fixing the room acoustics, a sub will usually make matters worse — although you can ery occasionally get lucky by placing the sub somewhere that doesn't excite all the bad standing waves!

[jaminem]

Hi there
Re bass trap location, as Hugh says corners are a good place to start, but can I also recommend behind the desk on the front wall, with the most being up high where wall meets ceiling. Same on back wall- this is typically ‘dead space’ so a good location for it. Get some thick traps behind your speakers too if it doesn’t compromise your listening position- bass goes out the back of speakers as well as out of the driver on the front regardless of where its ported.

Also ceiling cloud - this can help too - again dead space up there. Re windows although they can act as a sort of bass trap if you have a deep window sill bass can build up in there, which can also bugger your imaging as windows are rarely on both sides of the room in the same place.

That mirror behind one of the speakers has got go!

Finally manage your own expectations here. Even after doing all this work it’s unlikely you’re going to get more than about 4db improvement - you may be lucky (I hope you are) Especially in that huge null you have at 100hz - the room is just too small. I do very bass heavy music in a similar maybe slightly larger room and have as much bass trapping in there as is possible and I still have a 6db null at 60-70hz. I use sonarworks to sort this so it’s workable but I’m still checking on headphones.

My trapping is GIK in the main….

[jellyjim]

In terms of bass traps in corners, if you can't avoid an obstruction, is it effective to place the trap as near to the corner as possible?

For example, the picture with the guitar cases, I can move those and snuck a bass trap behind them. Whereas, if the bookcase (second picture) must be in that corner, can the bass trap sit in front of it? The bed is definitely moving.

[jellyjim]

My trapping is GIK in the main….

Which of their bass products do you use? The Turbo Traps (the cylindrical ones) seem interesting. Practical, too. Something for the potted plants to sit on!

I do very bass heavy music in a similar maybe slightly larger room

Have you been able to incorporate a sub into your room?

[Sam Spoons]

Bass traps don't have to be symmetrical so if you could move the bookshelf a foot to the right you could build a bass trap that fits partially behind it*. I guess you'd lose a little efficiency but you could have a bigger volume of Rockwool (and more depth in one dimension at least) which are major factors in how effective a bass trap is.

* Ideally I'd build a full sized (or over sized) corner trap with one corner cut off to allow the bookshelf to fit closer to the left hand wall.

[jellyjim]

Bass traps don't have to be symmetrical so if you could move the bookshelf a foot to the right you could build a bass trap that fits partially behind it*. I guess you'd lose a little efficiency but you could have a bigger volume of Rockwool (and more depth in one dimension at least) which are major factors in how effective a bass trap is.

* Ideally I'd build a full sized (or over sized) corner trap with one corner cut off to allow the bookshelf to fit closer to the left hand wall.

Do you advocate DIY Sam? No need to go into construction details (there's a zillion YouTubes on that!) but curious to know if the general consensus is, "Yes, you can DIY effective solutions", or whether it's a bit of a myth. I mean, if the average DIY solution is a third as effective as commercial products then I probably wouldn't bother. But two-thirds as, three-quarters as, that starts to seem worthwhile given the cost savings.

[Drew Stephenson]

My room treatment is entirely DIY and, with a bit of assistance from Neumann, is within +/- 3dB of target between 23Hz and 18kHz, so I'd definitely suggest it for things like bass trapping and broadband absorbers.

[jellyjim]

My room treatment is entirely DIY and, with a bit of assistance from Neumann, is within +/- 3dB of target between 23Hz and 18kHz, so I'd definitely suggest it for things like bass trapping and broadband absorbers.

Great!

Nice results, too

[Sam Spoons]

Like Drew I did my own acoustic treatment and, while I haven't measured mine, the room sounds very good. There is no reason for DIY traps to be any less effective than commercial ones, the part that is doing the absorbing is the same stuff, usually a chunk of Rockwool, and it will work just as well hung on the wall in an old pillow case as it will in a professionally built wooden frame. The main advantage of professionally built panels is appearance but it is possible to get very close with care if you use the right fabric to cover them.

I bought my fabric for covering mine from Gik and they were very helpful. My design for a simple broadband absorber which is much easier to make than most on youtube (if you have 10 to build simplicity means speed which gives a time saving as well as keeping material costs to a minimum) is here https://www.soundonsound.com/forum/view ... IY#p783500

[jaminem]

My trapping is GIK in the main….

Which of their bass products do you use? The Turbo Traps (the cylindrical ones) seem interesting. Practical, too. Something for the potted plants to sit on!

I do very bass heavy music in a similar maybe slightly larger room

Have you been able to incorporate a sub into your room?

Hi There, I have a mixture of monster traps, soffit traps, tri traps (in the corners) and home made rock wool traps, with some diffusion/absorption at the first reflection points. I try to keep the room as symmetrical as is possible

If I was starting from scratch I would use mostly soffit traps - they treat down to the lowest frequency and as they are square they (for me at least) are easiest to mount - I would put them in each corner and then build a ring round the top of the room where the wall meets the ceiling (its also a corner you see) but I would still treat the front and back wall and the first reflection points. You can, with a bit of framing get the same effect with rock wool. The trick with smaller rooms I think is to balance as must bass trapping as you can with it being actually useable - as others have mentioned you can never have enough bass traps, but you actually need to be able to move in the room and work too! Hence using the wall ceiling area - its dead space.

I don't have a sub, I don't feel I need it - but I have Neumann KH310's which go really low (down to 34hz) so there's plenty of bass in there! I also think that a sub would cause more problems than it would solve just to get another 10hz extension - Im low cutting the bass end at 30-40hz anyways - its eats a lot of headroom and 99% of playback systems dont go that low anyways so its a reasonable compromise - im not doing cinematic scoring or sound effects played back on massive subs...
If it was me - I'd abandon the sub idea - your Genelecs go down to 45hz (admittedly at -6db) which IS enough and pile my time/resources into getting the room right. IF after that you still feel something is missing then look into it.

My room STILL has 2 troublesome nodes due to the size of the room - I just cant fix those, which sonar works helps with - in an ideal world it would be a bigger room, more traps and less sonar works, but that's life isn't it!

As others have said tho, if you're serious, the first step has to be to get all of the extraneous furniture out of that room, get it symmetrical and then give as much area as you can to the bass trapping - whichever you choose - DIY or professional.

I choose some GIK ones to take advantage of the range limiters they have in them - the top end/midrange is already pretty flat and I didn't want to take all the life out of the room....

[Drew Stephenson]

After demoing it at GearFest I did get a sub for my set-up, but not really for the low extension. Firstly taking the low frequency work away from my KH80s (along with the sound profile correction) has made them much more spritely and revealing in the mid-range, and secondly, careful positioning of the sub has almost completely got rid of a 160Hz room mode null that I had in the room (again finished off with the room correction software).
But I only went down that route once I was pretty happy with the treatment in the room.

[RichardT]

To control the lower frequencies well you’re likely to need a lot of broadband traps, or possibly tuned traps, as everyone has already said. Particularly if you want to hear what’s going on in sub-bass frequencies! That really makes the requirement tougher to achieve - you would without doubt need a subwoofer or new speakers to hear the sub bass properly.

I wonder if you can actually accommodate that in the room without interfering with it being a living space?

One option might be to have some movable traps that you can put into position when you need them, to create a kind of room within a room.

The other alternative, which is likely to be cheaper and more satisfying, is to use a good pair of phones. For that genre, in a multi-function space, that’s what I would do.

Then you could consider hiring a well treated studio space if you want to cross-check how it sounds on a monitoring system with good bass extension.

[jellyjim]

Neumann KH310's which go really low (down to 34hz)

God they're hot!

You're a cruel man. Why would you put those in my brain?

[jaminem]

Neumann KH310's which go really low (down to 34hz)

God they're hot!

You're a cruel man. Why would you put those in my brain?

Sorry bro. Max and Hugh told me to do it….