Basstrap: EQ Acoustics or HOFA ..or DIY?

[3ee]

WOW, just wow! ... after applying the carefully generated and touched stereo IR correction filters to bring to +/- 3db (below 2k) the sweetspot focus is simply outstanding, extraordinary!

It's like when you switch from normal yet good speakers to near field monitors
Then the same wow factor goes when you acoustically treat your room
...and finally... when applying carefully calibrated corrective filters on top of all.

I had been doing this before (incl generating corrective filters) ... but now I fully "get it" , it all became clear where my room was in the way.

One thing to mention for other people reading through this thread and thinking they can get away with just corrective EQ ... forget about it! You should treat your room 1st -as good as possible- , then put "some" corrective filters on top at the end of the process.
(by "some" here I mean you don't have to compensate for every comb-filtering peaks/dips or whatever ... use intuition to apply only what's necessary and don't aim for "perfectly" flat ... aim for uniformity in general. )

[camsr]

Sometimes you can EQ a mode, but it's never possible to EQ a reflection.

[Itaro]

Hi Compyfox,

I also live in Berlin and would like to build broadband absorbers (about 10 thick) for my new studio (room size 3.5m/5m Altbau), since my German is not great yet... I'd really appreciate your advice.

If you were to build your broadband absorbers today, which material would you use for them? to reduce cost I would naturally preferred material available in Berlin or Germany.

Thanks in advance!

[Compyfox]

I'd actually go with Rockwool or Knauf Insulation.
There are two companies that provide such material, which are also along the lines of "pro brand" specs.


If you want more "bass absorption", then go with +/-6kPa "Sonorock" by the company "Rockwool". They ship packages of 10cm slabs, and there are about 6 of them in there. The 4cm material has 10 slabs per pack. I used 4cm and 10cm material myself.

Hint from my side:
Wall absorber frames should be 12cm deep (so 2cm air gap, 10cm absorptive material), corner absorbers can be 10cm deep since you mount them in the corner anyway.


If you want thinner absorbers with better mid/high frequency absorption (for example: ceiling counts, room dividers, etc), then you should look at KNAUF Insulation. They have thinner slabs with higher flow resistance (11kPa), see page 1 for charts and more info as to why.

I didn't try these yet, but the material is called "Akustik TP 440" and "Akustic TP 120".

Hint from my side:
You can create thin absorber panels that are only 4cm thick. But they're more aimed to cover the "mid to high-range". For gobo's/room divers I'd use two slabs a 4cm to get to at least 8cm thickness. Add a 2cm air-pocket between these two slabs, and they're getting even more effective.

In fact, i want to rebuild my current Monster Gobo/Room Divider from 125cm width/200cm height/20cm deep into 62,5cm width (size of the slabs)/180cm height/10cm deep - so that I can make a folding screen design out of that (better to transport, better space usage on my end)




Summed up:
Corner Traps: 6kPa
Broadband/Gobo/Ceiling Cloud: 11kPa



Where to get that stuff in Berlin:
FORGET BAUHAUS, Obi, Holz Possling and Hornbach for this. You need to go to Dämmisol. You pay about 30-40bucks per package, and you should have somebody with a wagon or mini-van to transport that stuff (it's exactly between two S-Bahn stations). But pickup is way cheaper than delivery.

Wood - if you want to keep things light but risk warping (if you didn't dry the wood properly or have a slightly humid apartment), go with Bauhaus. They have 25cm width pine panels. But they did raise prices in terms of cutting boards (even the so called "glued lumber" ones) - formerly free, now 1EUR/cut (what a ripoff IMO!). At this price, INSIST that they cut right, or they have to do all over at their own cost (I had huge quarrels with them about this!). Especially if you don't have access to a table saw. My frames are all 12cm deep, and since the Rockwool panels are 62,5cm x 100cm, I designed the frames to "fit around".

The "non-warping" solution is to go with Plywood. Birch Plywood at 15mm thickness costs 30EUR/m2, and 18mm thickness is 34,50EUR/m2. Let's do some quick math with a frame fitting for a 62,5x100 slap, 12cm deep, 18mm thick material. That's 2x 103,6x12x1,8cm (0,12432m2 each) and 2x 62,5x12x1,8cm (0,075m2 each). That's about 2x4,29EUR + 2x2,59EUR = 13,76EUR/frame. Not counting screws/dowels and glue, or the work assembling them. Neither fabric if you want to wrap your panels (which you should either way!)

I got away WAY CHEAPER with 7EUR wood panels (250cm width, 2000cm long, 1,8cm thick), cut down to 4 frame pieces (read: you got one frame out of it). The cutting was free back in the days. Not anymore. So you pay about the same now with Spruce/Fir or Pine (solid wood, glued together) - might as well go with Plywood for better looks.



Painting:
If you wrap it in Linen anyway - just ignore the workload. Unless you want to seal them. Then aqua based lacquer is more than enough. 20L cost you about 12-14EUR - more than enough for 6-8 frames, with 2 coats each - but the build time is super long! I did this, because I wanted to create an "open look" - should have gone with "wrap them instead!" - so much faster and if done right, they look like retail versions.



Fabric:
Depends on where you live in Berlin, and what you look for (with patterns or not). But "Kreuzberg" has various Turkish markets (great for spices, various types of fabric, sawing material and vegetables - but that just as sidenote). There is one with a booth from a German cloth/linen supplier I regularly go to. The material I went for was usual 170-180g/m2 of Linen. Didn't care washing the starch out of it, just stapled it right on. Though I have to admit, I did use one sheet of Linen for the Wooden Frame, and otherwise the rockwool was wrapped separately.



This should keep you company for about 2 weeks, depending on how many frames you want to build, what material you have at hand already, what type of tools, and how "deluxe" your panels should be.

But at 200bucks of material costs, you can EASILY cover a 10sqm room from floor to ceiling (though in your case, that's 17,5sqm)





Even though I'm far from being an expert, maybe I should start a tutorial series, or local classes about this topic... hm...