Tiny All-In-One room

Hello people, A few days have passed and there are things to share with you. As you may remember I was about to build my upper soffit slot resonators, and that's what I did: And this is what I got after a loooot of effort: No matter how I tried to tune, retune or detune them, the results were not satisfactory at all... There was a huge hole in the lower midrange reverberation time while in the lows there was a weird rise of about 100ms (!!) with no real improvement anywhere. The evidence: https://mega.nz/file/IhVQTZwA#KJtyaK5uW ... D6MWOx0QOU The only logical conclusion I can reach to is that sound coming from inside the soffit where interfering with the resonator. It seems my soffit construction is not massive enough to support this kind of treatment built into it. That's why almost nobody does these things, failure accepted and lesson learned. :) So it is time for plan B, and plan B was to turn the resonators to big insulation chunks: At least that 150hz dirt has disappeared.. but strangely the very lows RT is still high and the rest is bumpy... :? I am tempted to convert the side lots to insulation too. Later, as I was making the frame for the absorptive ceiling I thought it was a good idea to screw some slats (50mm slats/20mm gap) over the upper insulation chunks: And there is was. Evidence: https://mega.nz/file/sxME0bRS#7I2VGIiKM ... _r53mdc-3s Minor changes, most of the RT is back to normal except this annoying low section... It also seems that I have reach a point that in such a small space every thing in every place affects the measurements in various ways. Anyway let's move on! Cheers Dio

keep in mind, you can eq out the peaks 8)

I do Glenn, but I want to keep eq as my last resort.. Cheers, Dio

Ceiling Update! Finding it easier (and perhaps more efficient) to just make a full absorptive ceiling (27cm insulation 5000 Pa.s/m2) than drilling and hanging clouds in a 2,5m high room, I got to work: And some happy results: mdat: https://mega.nz/file/B0U32Ywa#oBu208tE8 ... w-b7X8cj8I A nice view of all the spectrum <700hz get smoothed, specially these 150-300 spikes in time. The 250hz resonance is the radiator still singing and the big 120hz null is the floor bounce at 4,5ms (verified with the string trick) that made itself apparent when the (absence of ) ceiling cleared things up. Then, it was time for these side slot resonators to be converted to insulation chunks, I didn't forget them! mdat: https://mega.nz/file/EtchlaLZ#gopaS-DQI ... JoFnUSOnl8 What we are seeing is a further smoothing of the 150-400hz area in the time domain and at last some damping if our old friend the first 42hz mode being visible in all the time related plots. That was nice! The radiator (250hz ringing) is still there, but not for long.. One more good thing I noticed after finished all this is that the ventilation is completely inaudible even at full speed and the playing music (Muse) at 100dbC in the room corresponds to about 57-59 dbC of low frequency rumbling just next to the ventilation baffle box outside, ok with that for now. My next move shall be the first side wall reflection treatment with 18cm absorption (as seen in post at the top of the page) and with a feeling of adventure the making of a limp mass absorber in the blank space between the soffits in an attempt to tame this 42hz mode. Also you may have noticed that I haven't make any comment on the frequency response in all these posts. As you can easily see from the plots attached frequency response tells very little about the acoustic quality of a room, it is relative easy to make a good frequency response graph by heavily equing the monitors but what first matters is a correct time-related behaviour of the room, and that's what I am trying to accomplish, equing will come last. Thanks for viewing, Dio

Looking good! How does it sound?

RFZ Update. Two panels 200x60cm of 18cm insulation + 12cm air gap installed in the first reflection points L-R respectively. Results following: mdat: https://mega.nz/file/k1sERSoZ#TrpUgjJZq ... TpU5qROJzM Nice things happened here summarized in a word : smoothing. From frequency response to waterfall to Spectrogram, every plot has been beautifully smoothed and this is also easily audible. One interesting thing to notice is that the temporary placement of the amps on the floor (see photo) has effect in the floor cancelation.. The RT is now very short, with is natural with all this insulation, what is not natural and needs investigation is the strange behaviour of the low frequency decay with its ups and downs in every measurement. Anyway generally things improve and as we can see from the before-after rfz panels comparison the listening position is almost free of first strong reflections. Despite the very low RT the room does not feel dead and been there is not uncomfortable at all, the hard front wall is a good choice.. Listening music in there is apocalyptic I would dare to say, you can observe easily every detail in the recordings and at the same time get involved in the music as a listener, not as a technician, I like that! One more thing a trained eye can notice in the room photo is the absence of the pc tower, and this is why: The box is not sealed yet but the pc working is barely audible only as a low frequency murmur. Coming next is my last attempt to do something new with my 42hz demon. DIo

42hz -> EQ cut. :-)

After a long time back here to continue that small project. What I had was a small cavity between the soffits, ideal to build some limp mass absorbers, why not? And then painted the soffit wall to look like wood and put some fabric and lights. To verify thet the absorbers are tuned correctly I swept simple tones from 30 to 55hz and by lightly touching I felt the membrane begin vibrating from 36-38 hz and stop at about 45-47 hz, so I guess the constriction is correct. Measurements: mdat: https://mega.nz/file/Q8lGVD7J#iu4kbnZol ... qH00LuYmXc We see that the two mlv absorbers did something in the 40something hz area, but very little, perhaps their 85x165cm surface is not enough? Anyway, they smoothed the upper bass area and that alone is fine. More to come in a few days.. Dio

as noted in Stuart's site, a peak can be reduced via EQ. not that you're EQ'ing your room, but something like a single well-defined peak is a perfect target for energy reduction.

I will definitely eq this peak out Glenn, when I will have the room ready for speaker tuning this will be the first target! Dio

Looking good Dio!

Hello, I realised that I left this thread with no updates for some time, so here is one! After making the diaphragmatic absorber (with its not so good performance…) between the speakers, it was the time to finish the plan I had (see post #15) with the angled side slot resonators (wings). The idea was to try to make this tiny room not feeling dead and unpleasant, without further compromising its already difficult acoustics. So following J Sayers’s paradigm and my own calculations I used 2cm thick wood slats of alternating widths of 5cm, 10cm and 7,5cm and alternating gaps of 8, 12 and 5 mm respectively and cavity varying from 5 to 28 cm acting as a “ramp” from the first reflection absorbers to the end of the room. Building the left hand wing was easy, just made the frame, bolted on the wall, sealed, put the insulation, the black cloth and the slats and that’s it! But on the right side there is a window I wanted to somehow keep, so I built an extension in order to put a 1 cm laminated glass on the inside and make an isolated and angled window merged into the slot resonator. Not an easy job for an amateur like me… but with all the mistakes I always make I finally didi it. One more problem was the heater radiator which I wanted to keep, but its metallic construction sings along even with spoken voice…. not much but noticeable. So I made a smaller wedge resonator, packed it on the radiator with foam between and that was the end of its days as a singer.. And then I made some measurements: mdat: https://mega.nz/file/Ekd11QDD#OB6Ir3K5F ... EI8vcBzf9M Now the room is not only functional but also beautiful! One more super nice thing with this double window is that it has very good isolation from the outer world. Will take measurements on that. Update following soon. Cheers, Dio

excellent! i find myself designing a number of rooms with the window in the slat wall - sometimes i use cnc machined plexiglass on the slat side to mimic the slat/slots - mainly on outside looking windows - so the entire surface is acting as one, and the disruption to the view is minimal. i don't often do that for inter-room though as it can be a bit more obscuring than most folks would like.

Since I have sort of finished the room, it has been time to eq the speakers. I have a Void Acoustics Digidrive+ and a tri-amped setup, so a lot of flexibility. After a couple of tries and a ton of eqing I came to this state, with is a big improvement to the previous one. .... continues... dio

But this 40hz resonance was still there strong and proud, so I made the decision to revisit the MLV absorbers. I drilled two “pressure equalisation holes” (one each) sealed them and re-sealed some parts that the caulk seemed to have cracked. And then I took some measurements. And after a few eq refinements finally I was happy! The 40hz spike is now tamed for good, even without the notch eq it has been drastically damped, I guess now the mlv absorbers do what they were supposed to do… I finally tried the “House curve” eq that REW has, and kept it, flat is too treble and results to dull and bass-heavy mixes.. And a comparison of the three at 1/3 oct: mdat: https://mega.nz/file/s0cnRSaT#7ynt6sX5SWYlsgJbTovUYsSI68zRa6cKgMnPau7Fm6Q It is amazing how this awful tiny room has transformed to something workable and enjoyable.. Now I need to make a proper desk. :wink: Cheers, Dio

After utilising the B&K curve and a shallow 6db/oct hipass at 20hz I now have these results : A nice comparison between the two curves: and a more natural sound, indeed. No harsh or lacking treble, no dinosauric or absent bass, everything seems (listens??) as it should without any "is that know good?" alerts Thanks for viewing Dio

congrats!

Thanks Glenn!