mixing room treatment - one more newbie looking for help

[T.V. Eye]

Well, as promised here are some pictures of the progress I made so far. As you will see I went for the "corner block variation" of a superchunk, as I was to lazy to cut all this triangle pieces .


Two layers each of 20 cm thick mineral wool cut to 30 cm depth (couldn´t do it 40cm because of the window), fixed in the corner with some chicken wire. I fixed a slat at the wall, and than used a staple gun to fix the chicken wire. I could go directly into the ceiling since it´s drywall, no need for a slat there ...

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...covering with fabric, also with the staple gun...

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One side finished (the excessive fabric still have to be cut away on that pic):

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Frame at the rear wall...

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...filled with two layers of mineral wool, the one at the back slightly smaller than the top one to get a little angle...

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the finished rear wall (except for some fine tuning of the fabric in the corner), I didn´t need the chicken wire there, just the fabric keeps it in place:

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Frame for the front wall superchunks...

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...filed with two layers of mineral wool that makes the superchunks 40x50 cm thick...

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...and covered with fabric:

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And the ceiling of the front wall during progress:

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That´s all finished now except for some thin slats I want to user as a "end strip" (correct term?) to cover the stapled endings of the fabric - just for decorative reasons.
All in all it was a little more work than I expected. Maybe I underestimated the fact that I have to do it all alone - and that I did something like that for the first time. I think with two people it would be a lot easier. I probably looked quite silly on the ladder, pressing the mineral wool in the corner with one hand or even with my head, stretching the fabric with the other an the staple gun between my knees ... But I´m happy with the results so far, so no reason to complain.

The question is, what to do next? I think the ceiling should be the next step. The room already sounds a lot better (subjectively, as I couldn´t do measurements right now), it´s really "dry" now except for some HF-flutter echo that is left.

John often recommends two clouds for small rooms like mine, angled and with a solid top. The one at the front wall rises to the center of the room, and the one in the back falls down to the rear wall, like this one: http://www.johnlsayers.com/phpBB2/viewt ... 431#p98431
Would it be a good idea to do it that way?

Or are there any other recommendations what to do next?

First reflection points? I´m thinking about building some mobile units (you call them gobo, right?) and place them there. That would give me the possibility to maybe use the rear of the room for some vocal overdubs or for recording some acoustic guitars etc., and move the gobos over there for that purpose.

Rear wall? I´m not sure what to do there. My idea with the VPRs turned out to be quite expensive, just the acoustic foam and the metal plates for two 1x1,5m absorbers would be about 300 €.

Front wall? I would like to keep this untouched until the rest of the room is done, so I have the possibility to move the speakers and maybe build something for soffit-mounting later.

Best regards,
Thomas

[gullfo]

the solid back clouds would work. or simply absorptive clouds. or several angled ones with various amounts of hard surfaces. depends on the desired effect and if you have room modes which need to be handled that way. the mobile side absorbers are an OK idea but most times best to find the spots and leave them. build mobiles ones for the other purpose. the back wall could be more absorbers, absorbers covered with widely spaced slats, or even an angled slat resonator.

[T.V. Eye]

Thanks again, Glenn.

I stuck a bit with the ceiling, because I still think about what to do with the original ceiling. Just paint in an use so large (or many) clouds that it won´t matter if the rest is untreated, or cover the whole thing with at least something a little absorbent. I should be clear with that before mounting any clouds.

In the meantime, I have build 4 simple panels, 10 cm mineralwool in a wooden frame, covered with fabric, 1,10m x 80 cm, so if I put one on top of another, it will be nearly floor to ceiling (correctly, up to the upper corner absorbers). With the superchunks at the frontwall 50cm into the room and the 80cm panels aside, If´got 130 cm of "pure sidewall absorption" , that should cover all first reflections (except for the ceiling of cause) as my listening position - following the 38% rule of thump - would be around 1,5 meters.
I will use them at least temporary as "mobile units" so I can move them around a bit, and even to check other probably "critical spots" in the room.
I still can fix them to the wall later, or build something a little better like johns sidewall-slat resonators, and use the panels somewhere else, store them away for the case that I will do some recordings in the room, or even take them to our rehearsal/recording room.

But with the corners done an the 4 panels at the first reflection points next thing I want do is take some measurements with RoomEQ Wizard. I took some in the emty room before I started this "project", so I hope that will give me a little more objective information what already changed and what more is needed. Could be helpful to check how critical the floor to ceiling room modes are, and than to decide what kind of clouds to build, wouldn´t it?.

Oh, and yes, the backwall will get more treatment for sure. For the measurements I think about using some of the mineralwool that´s left (still 7m x1,2m 20 cm thick) and just lay it against the backwall to check what changes with or without it.
But I think in the end I will need something a little more reflective there, like spaced slats up front as you mentioned, or maybe even some diffusers, like Ethan Winer promotes a lot (yes, I know that diffusion in a small room is considered very critical, just thinking about it as an option). I fear that otherwise the room will get a little do dead in the hights and mids, but that could be the case only because I´m yet not used to the room sounding so dry as it already sounds now compared to how it sounded before.

Anyway, that decision will come much later. The ceiling will be next after the measurements are done.

Best regards,
Thomas

[gullfo]

Depending on close the clouds are to the ceiling would determine if you need more absorbers underneath. If you're off the ceiling by more than 300mm, I'd add them.

[T.V. Eye]

The room is about 2,7 m high, so I think 300mm would just be roundabout the distance where the clouds should go?

It would probably be better to cover all of the ceiling to be "on the safe side", and than use clouds just for optimization. But I´m still not sure what to use. Mineral wool would be dificult to fix up there an to cover properly, especialy as I dont want to do too much drilling in the ceiling since the room ist rented and the clouds will already need that.
The best would be to have something that could be glued, but when I look for comercial products, there are only this polystyrene panels that probably won´t work as a good absorber, or acoustic foam, this ugly gray pyramid-shaped overpriced stuff.
I think it´s time for another "sightseeing-tour" at my lokal home improvement store, maybe I find inspiration for something that will work.

[T.V. Eye]

Well, I just finished the measurements. Both the before and after where done "quick and dirty", so maybe the mic position was not a 100% the same, the speakers are still on my desk etc., but I think the setups has been quite comparable to each other.

So here are the graphs (I followed the max. 700pixel width forum-rule, so not much details):

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1st treatment fr.jpg

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1st treatment wf.jpg

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1st treatment ir.jpg

Well, the frequency response is still far from great, in some areas even worse then before (the "holes" around 4khz and 16 khz, plus the big null at 200hz that wasn´t there before), but the bass range is already a lot flatter.
And the improvements in the decay time are huge, from 750ms to about 250ms, and the waterfall speaks for its own, I think.

But that´s only the "scientific" part of the story. The other part is, after I finished the measurements I could hear the (so far) treated room for the first time under real listening conditions through my monitors, not the old hifi-stuff I set up during the last weeks while I was working at the room - and WOW, what a difference. I mean, really WOW!!

I just played some of my favorite records that I also like to use as a reference. Abbey Road was first, an here comes the sun was never so sunny, I thought about getting my sunglasses...
Coltrane/my favorite things - so intimate, Slayer/reign in blood - so much punch, Euro Boys/long days flight - so much detail, I just jumped from record to record, Black Sabbath, Nick Cave, RZA, Brian Auger, The Notwist, Miles Davis, Madonna, Lee Hazlewood, Johnny Cash...
OK, I won´t get to enthusiastic, but anyway, the difference is huge. Especially the bass is so much tighter and more focused, the stereo image spreads out much better, and lots of detail reveals that were hardly there before.
I expected an improvement, but not that it would be so dramatically so early during the process of optimizing the room.

Well, yes, I know there is still a lot to do, but a great feeling to know that I´m on the right track.

OK, enough for todays "report"...

Thomas

[gullfo]

the 200hz is probably the 3rd axial mode off the ceiling. this is where the solid back clouds will help disrupt that.