Room treatment advice

[tarkus]

Hi all,

 

Recently got a batch of CSR Martini Absorb XHD 100mm and put it all around my room. It definitely sounds better in terms of clarity which I'm happy with. I actually have 6 whole panels unopened, and am considering using them or selling them (don't mind either way, the money from selling is not paramount). 

 

Here is my room, all the black stuff is the XHD:

 

 

The corners I just have single small panels, I know it probably isn't doing much:

 

The RT60 measurements have gone down are now around the 300-400ms range. Here is my frequency response:

 

 

This is before DIRAC, which I will be applying using my SHD Studio. I'll probably bump the subs a bit before DIRAC for a house curve but the above is set flat-ish.

 

What would be the best way to try get rid of the troughs at around 200 hz using my remaining XHD panels or is it not possible? Does it even matter when I will be correcting with DIRAC (although I've found it doesn't correct as much as I'd like - I'm still playing with it)? Also, would there be any benefit just double stacking my remaining panels so it is mostly 200mm thickness of XHD around the walls?

 

If it matters, equipment is:

- Minidsp SHD Studio

- Topping D90SE for the mains and E30 for the subs

- 2x Benchmark AHB2

- Revel F206 and 2x Rhythmik F12 subs

 

Many thanks

Edited October 29, 2022 by tarkus

[Elnido]

Nice gear always wondered about the Rhythmik subs.I cant help with the trough however I think your room has too much absorption.Try some diffusors at the first reflection point of your speakers the improvement will not be subtle. On youtube there is a handy video from Martin Logan on how to get best sound from a subwoofer,could be of benefit to you.

[HdB]

You can also add some strips of high freq reflecting material on the front of some of the adsorbent panels to increase some of the treble and "air" in the music - this will need another re-evaluation via the Dirac but you might find the result pleasing.

 

Diffusion is also excellent but unfortunately not cheap.

[jmc100]

"What would be the best way to try get rid of the troughs at around 200 hz using my remaining XHD panels or is it not possible?"

 

It depends if the 200Hz is a result of standing waves or your speakers' response. Easiest way to know is by looking at room dimensions. The ceiling height looks quite low, so assuming its around 1.7m, 200Hz its most likely a trough (or null) between standing waves.

 

Best way to approach this is target membrane absorbers, OR to treat the corners with double or triple layer of your XHD. The latter is a more 'spray and prey' approach - it would tame the peaks AND troughs of the room response but will take some mid bass and mids/highs out of the room too. Might need to experiment a bit

 

If its not modal then then speaker tuning/cross-over points etc.

 

hope this helps

[almikel]

XHD is totally wasted "on a boundary" from a bass absorption perspective - worse, it soaks up lateral treble reflections, which can make the room "too dead" very quickly

 

You have a dedicated room with so many options - IMHO the approach you've taken may not be the best use of your XHD.

 

Your FR is great apart from the dip at 200Hz!

Can you show your waterfalls and RT times?

Run a measurement full range from the listening position then another say 20Hz to 400Hz (an octave above the 200Hz dip) and post results.

 

cheers,

Mike

[tarkus]

Thanks for the replies and sorry for the late response.

 

With work and a little baby at home I've only had little bits of time here and there to experiment.

 

The first thing I did was try double layering the XHD panels, with disastrous effect with a massive bass dip which I could not get rid of no matter what I did. After weeks of moving stuff around I decided it was best to give up and go back to a single layer as in the OP. 

 

The thing is, even though I posted here for advice, I was actually pretty happy with how it sounded and wasted weeks by being a bit greedy, should've just stuck with what I had haha. I'm now pretty happy with what I have, although it does still sound a little bit compressed. As per the advice above I might try some diffusor panels at first reflection points, perhaps on top of the XHD panels. But for now I'm sick of doing measurements and want to just enjoy the music for a while

 

Any suggestions for good value diffusor panels?

[cdave]

27 minutes ago, tarkus said:

Any suggestions for good value diffusor panels?

A diy curved diffuser made from 3mm mdf or ply, 600x600 with 100 - 150mm bend is cheap and  effective. Bunnings cut the 1200x600 mdf for me.

To find the best sounding curvature, I lashed some chord across the back of the mdf to adjust the bend. 

[HdB]

With all the XHD panels around the walls, you're effectively absorbing much of the treble and upper mid frequencies that creates much of the indirect reflected $ delayed sound at your listening position would/could start to sound like headphones or an overdamped studio sound - you may like this and if so, don't change a thing 

 

If you're using the dirac to increase the upper frequencies to compensate for the XHD absorbtion, the normal procedure is to bunch a lot of the black panels at the junctions of any 2 or 3 walls/ceiling and leave the flat surfaces undamped except at that first reflection points 

 

Naturally, there's a wide range of adjustment so I'd be a bit hesitant to aim for the measured Rt60 as a defining ratio as it's principally designed for pro-audio situations - Rt30 is a more useful measurement as you can better use it at higher and more realistic volume levels too - your listening level at that fantastic chair will be somewhere in the mid to high 80dBs, maybe higher 90s for R&R! 

 

Diffusers are something that needs larger areas to be effective - single units at first reflecting points like sidewall and ceiling can be useful but you need a number of them together to get useful results - for example, single Schroeder 1D panels at the usual 500mmw x 1200 high aren't going to do much and you need an array of them to be effective, and as they're not the cheapest product around, the cost can quickly get out of hand - you can build some of the simpler "leanfusers" (design from Tim Perry, Arqen Acoustics) in wood or styrene that does the same job.

 

If you're interested in creating a higher indirect sound, the rear wall behind you is the place to start with nearly the whole wall of 1D diffusers (preferably loaned or borrowed) and a good thick wedge of the XHDs (maybe 200mm thick) diagonally across the corners for bass absorption.

 

That cathedral (sloped) ceiling can be a problem too but maybe the Dirac can compensate tor this.   The thick absorption on the front wall between the speakers is something I would try removing to see if the effect is pleasing to hear - on the other hand, standing a large tv screen there (a fairly common situation) isn't recommended either!

 

...  just my 2 cents

[almikel]

On 14/11/2022 at 8:40 PM, tarkus said:

Any suggestions for good value diffusor panels?

If DIYing, then deploy vertical slats in a 1D Binary Amplitude Diffuser (BAD) pattern over the absorption.

 

Better still, apply black builders plastic over the absorption 1st, then add slats over the builders plastic.

 

The builders plastic will reflect higher frequencies back into the room and improve bass absorption.

 

You would also significantly increase bass absorption by pulling out the floor edge of the absorption so it "straddles" the corner - air gaps improve the bass performance of absorption.

 

1D BAD patterns are easy to generate - choose a slat width that's easy to source, preferably the material has the same height as your absorption eg Bunnings 100mm wide x 16mm x 1200mm  fence palings https://www.bunnings.com.au/100-x-16mm-fence-paling-h3-treated-pine-wet-1-2m_p0120830

 

Say you choose your slat width at 100mm wide - now just toss a coin many times - heads = slat, tails = gap - that's a 1D BAD diffuser.

 

BAD diffusers don't provide as much diffusion as say Quadratic Residue Diffusers (QRD), but IMHO they're ideal for adding over the top of existing absorption to bring treble back into the room with diffusion.

 

cheers,

Mike

[tarkus]

Thank you for the excellent replies and sorry for the late response!

 

On 15/11/2022 at 11:53 AM, HdB said:

Naturally, there's a wide range of adjustment so I'd be a bit hesitant to aim for the measured Rt60 as a defining ratio as it's principally designed for pro-audio situations - Rt30 is a more useful measurement as you can better use it at higher and more realistic volume levels too - your listening level at that fantastic chair will be somewhere in the mid to high 80dBs, maybe higher 90s for R&R! 

I've been listening a bit more now and I do think the music is a little bit "compressed" sounding, and it is hard for me to push beyond 80db. Is this due to the overdamping? Essentially I'd like amore "relaxed" sound which will allow me to go higher dB without fatigue, while keeping the detail and clarity which has come after I put the XHD panels in. Will the diffusors help me achieve this?

 

On 15/11/2022 at 11:53 AM, HdB said:

If you're interested in creating a higher indirect sound, the rear wall behind you is the place to start with nearly the whole wall of 1D diffusers (preferably loaned or borrowed) and a good thick wedge of the XHDs (maybe 200mm thick) diagonally across the corners for bass absorption.

Do you recommend the diffusors on the first reflection points and also the back wall?

 

Thank you for all the suggestions for the DIY builds of the diffusors. I've thought about it but unfortunately I lack the skill, patience and time to build these at the moment so will be looking to source some cheap units.

 

Will this or this suffice and any tips on which would be better in my situation?

 

Cheers

[davewantsmoore]

2 hours ago, tarkus said:

Essentially I'd like amore "relaxed" sound which will allow me to go higher dB without fatigue, while keeping the detail and clarity which has come after I put the XHD panels in. Will the diffusors help me achieve this?

 

Do you recommend the diffusors on the first reflection points and also the back wall?

 

Really need to look at detailed delay charts to know whether diffusors or absorbers or nothing is what you need.    Looking at your room, I'd assume you need nothing.

 

So I would recommend you look at your target curve ing DiracLive, and change ti to get the sound you want.

 

Your before Dirac measurement posted above are quite good, but the 400 to 1Khz range is bit elevated, and this will sound "unrelaxed".... but you can get what you want with your dirac target.

 

 

The 200Hz is almost certainly an interference from wall, and so treatment won;'t fix, only moving chair or sources..

 

 

[HdB]

As usual, Mike makes a good bit of sense with practical procedures 

 

Um, your Revel 206's are rated at 88dB do there shouldn't be any problems getting higher dynamic response well into the 90s at their rather flat freq response - from your photos, you've set them up with minimum 'toe-in' and about 10 ft distance so the stereo image/.width should be rather good, etc

 

So, this suggests that either the surround of the XHD and/or the Dirac have over compressed the sound to limit the dynamic response - it's a bit vague using words so just a guess but try listening with a live recording to see if it's 'dead' - maybe not your favourite music but that J Cash at San Quentin (Live recording) has a lot of 'air' or 'room sound' and will indicate over-damped sound 

 

As mentioned above, having thick wedges across corners (all of them) will do more to absorb bass anomalies than anything else - adding the 'scrim' or plastic film reduces upper mid and treble absorption and is easy to try (that silver kitchen foil works really well and covering that with a dark fabric/plastic makes it invisible) - this needs to be balanced by any use of the subs and will depend on just what sort of bass sound you're looking for

 

Perhaps it's worth some time to reduce the black HXD from the walls and see if the dynamics in the music returns then slowly re-introduce some of the panels apart listening for an acceptable balance of the sound rather than measured figures on the charts

 

I haven't any experience with either of those 'Sonitus' diffusers - they don't seem to follow the standard dimensions of the Schroeder 1D design but that doesn't mean they won't do the job - the ones I've made are from medium density EPS (same foam as on building walls) so not sure if same results - they're not that cheap but you do get 6 of them so that'll allow a useful 3 X 2 sized panel - individually, I don't think they'll have much effect but looking at the 'Hey Now' website, I see the small panels on the walls are spaced quite a bit apart so this is something rather different. 

 

It might be worth a talk to Geoff Haynes at Hey Now HiFi in Melb about these panels as he seems to be doing quite a lot of work in this area - a welcome trend in hifi retailers.   The "genuine" solid timber Schroeder 1D diffusers are expensive, and again, individual panels aren't very effective so the cost ...   

 

As Dave mentioned above, that 200Hz dip is most probably created by room dimensions and it's not so easy to combat 'standing wave' cancellations without changing listening/speaker/etc positions - just adding something like +8dB on the dsp at this point introduces other complications 

[tarkus]

Few more weeks of sporadic listening and I think I've found the main problem  that I've been having... the chair.

 

I forgot to mention that when I moved the absorption panels in I also switched from a small sofa (with no headrest) to the chair pictured in the OP, which has a fairly large headrest. It turns out if my ears are at or above the top margin of the headrest the soundstage is improved dramatically and I am happy with the sound. It's so obvious in hindsight but I still wanted to update the thread to remind everyone that a large headrest is significantly detrimental to sound quality. Luckily I chose a chair with an adjustable headrest having the ears above is not too difficult.

 

I'm now happy enough with the sound that I don't think I'll be changing anything anytime soon.... until I have the itch for new speakers  Thanks for all the help. 

[davewantsmoore]

12 hours ago, tarkus said:

It's so obvious in hindsight but I still wanted to update the thread to remind everyone that a large headrest is significantly detrimental to sound quality.

It makes quite a big difference.

 

This is my gheto listening chair.... the entire chair is audio transparent.    https://www.ikea.com/au/en/p/nolmyra-easy-chair-black-black-30233606/