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Basement rehearsal studio sound treatment...

post #1 of 8
Thread Starter 
I will be extremely grateful for any and all help, suggestions, ideas, insights that anyone can offer on how I should proceed with my basement rehearsal studio...
-- Thanks very very very much in advance!!

Okay, I've done a bunch of research reading books on studio design, and have spent weeks on the forums and reading articles on the internet, but after several weeks of reading and planning, I realize that I still have no clear idea what to do. Here is the situation, first in general, and then with relevant details below.

Studio space to prepare: Basement Rehearsal Studio
- Concrete floor, walls and ceiling – only 2/3 of the room is available to me (see diagram)

Purpose: Rehearse tap dancing, sax and tenor horns with microphones and audio processing, both hardware and software, and be able to use monitors while working

In the studio space:
- I'll be tap dancing and playing saxophone and tenor horn (not at the same time) w amplification, sometimes I'll be recording into a looper and everything will have audio processing (VST and hardware) in rehearsal as I hope it will be during my the shows
- I'll NOT be recording in the studio space except as part of rehearsal / practice (including looper work)
- I want to be able to hear the audio processing of the tap dancing, sax and tenor horn playing while rehearsing, live and without having feedback through my monitors
- I have a decent wireless in-ear monitor, but I dislike wearing it for hours at a time when working on new pieces and/or rehearsing
- sound pickup is through two AT8937 shotgun microphones (highly directional)
mics must be position on the floor for good pickup without feedback when tap dancing on the wooden floor
- I'm using a Shure SM57 microphone for the sax and tenor horn pickup
- Hardware includes GSP1101, Behringer LX1-B (V-amp rack), GP155, Digitech Timebender, Digitech Synth Pedal, various pedals including reverb etc.
- Software for live work includes Ableton Live with various effects and plug-ins, also using loops triggered with various midi devices including FCB1010, wireless midi keyboards, etc

Mixing:
- I'll be mixing (with Cubase and perhaps also with Harris MixBus 2) for shows, solo live performance with original music performed in small and medium theaters
- playback in the theaters will be either through a computer using my own on-stage mixers
- on the shows I'll be plugged either into my own active loudspeakers or using theater in-house sound systems of varying quality (I'm working in Germany, so the tech is usually medium to high quality)
- most often the music will playback in small black-box or medium theater/halls through some kind of active loudspeakers
- in shows I'll be adjusting to the space using a rackmount digital EQ with various pre-sets to anticipate typical theater acoustical problems
- NOTE: while the music is playing during my shows, there is almost always something else happening when it's playing (tap dancing that is amplified and processed, eccentric/comedic dancing, pseudo-mime, etc)
- my tracks are primarily composed using samples (mostly Kontakt sample libraries, incl Kirk Hunter Orchestra, Zero-G Spiritoso), VST devices incl CthuluArpeggiator, and loops (mostly Zero-G))

For the mixing sessions in my basement studio I'll be mixing using:
- M-Audio Studiophile DSM3 nearfield monitor
- in conjunction with a) Audio-Technica ATHM50S headphones and b) Focusrite Saffire Pro24 VRM (virtual room modeling) and soon either c) Beyerdynamic DT770 or DT880 Pro headphones
- I'll also be using a Focusrite Saffire Pro24 DSP with VRM (virtual room modeling)to test for different spaces

Summary: I am more concerned with having...

- a relatively dead room in which I can rehearse without feedback problems
- I want to hear the tap dancing with audio processing (picked up by shotgun mics) through the monitors and perhaps also a set of active loudspeakers
- and for the reasons above, having the perfect mixing studio is not so important (and which seems unlikely if not impossible, given the limitations of the basement space I'll be working in))

Thoughts:
- We've been thinking that we would build two walls set approx. 8cm / 3 inches away from the original wall, the new walls with metal or wooden studs floor-to-ceiling filled with 7cm / 3 inch Rockwool and one or both of the new walls built slightly angled in reference to the original wall
- We'll put 4cm / 1-1/2in rockwool on the ceiling over the tap floor area.
- We'll put stand-alone bass traps on the floor and bass traps in the corners where the walls meet the ceiling.

Questions that are immediately pressing:
- Should we use plasterboard, heavy fabric or something else to cover/finish the room-side of the second walls we're building that are filled with rockwool?
- What should we finish the ceiling with (over the 2“ rockwool)?
- Is it better to build standalone walls that are attached at specific points to the concrete walls for stability, or should we make the second walls permanent and build them out from the original concrete walls (leaving the air gap of course)?
- Question: I live in Germany and there seem to be two types of rockwool: pressed and loose, the pressed only going up to 4cm and the loose up to 10+ cm...?? Have I understood this correctly, that there are two types of rockwool?


Cellar Rehearsal Room
Walls, floor and ceiling are solid concrete..
ceiling height 2.25m / 7.4 ft
5.5m / 18.5 ft wide
3m / 10 ft + 5m / 16.4t on long wall (with 30cm indent)
a door on left, then 4.75m / 15.6 ft wide
 
See PDF at
http://bobethomas.com/music/Keller_Diagram.pdf

Where to position 2 shotgun microphones around/on the tap floor?
Where to position the active monitors?
Where to position sound absorbing walls, insulated ceiling, and what to cover them with?


Thanks again, Bob Thomas
post #2 of 8
You might check out Gear Slutz. They are little more geared towards studio spaces than this forum.
post #3 of 8
Hey Bob - First, good luck with your project. I'm sure you can make it work.

I think you have some conflicting goals, so you'll need to strike a balance for the acoustics. On the other hand, the sound isolation issues are fairly straightforward, even if not easy to implement. If you haven't already, you should read the articles at soundproofing company.com they are well prepared and detailed. I'm not in a position as an expert to advise you on the details of all of your questions, but I can give you a few tips.

When building new walls to enclose a quiet space, the walls should be decoupled, such that vibrations within the structure cannot be conducted to other structures. Wall assemblies should also enclose only one air space - multiple air spaces create resonant structures with low impedance at particular frequencies and result in overall poorer isolation compared to a wall built with the same materials but only one air space. Care should also be taken to seal any gap in the wall, including where electrical fixtures and air ducts come through the wall.

In terms of the acoustics in the space, I'm concerned you'll be unhappy with a very short decay time. Most musicians find it's easier to hear themselves perform with a slightly longer decay - maybe around half a second? (It could be that 0.5s is what you mean by dead - home theaters tend to be much shorter than live performance spaces. I think .3 to .4 rt60 times for home theaters are common.) While it seems you've done a lot of research, something you said made me unsure if you understood that all the treatments you apply to adjust the acoustics should be either free-standing in the space or hanging on a finished surface. For instance, you might build a light wooden frame and fill it with rock wool, then wrap it with a loose weave fabric, like burlap or the fabrics made by Guilford of Maine (GOM here on these forums) and then hang it from the wall or ceiling as you would hang a piece of art. The greatest challenge may be getting the decay times consistent over the frequency range of interest. I recommend you get REW, the Room Equalization Wizard software. It is free and will allow you to measure the acoustics as you adjust them.

I may have just told you a bunch of things you already know, but hopefully some of it is helpful.
post #4 of 8
Thread Starter 
Hopeful Fred,

No, your questions are good ones.

The issue that confuses me a bit is the difference between sound isolation and sound absorption or frequency dissipation and diffusion.

I'm not really worried about disturbing those living upstairs, since they are older and don't hear that well and the ceiling above me is at least 12" thick concrete.

The issue is that when I'm tap dancing on the wooden floor or playing the saxophone in such a small space, the original unprocessed unamplified sound in this room is so reflective, loud and resonant before processing that as soon as I turn up the monitors to hear what I'm doing, I have killer feedback... because the room is so live (all concrete, square room, 8 foot ceiling, etc.).

So the issue, as I understand it, is how to treat the room for sound absorption and frequency dissipation and diffusion so that I can crank up the monitors when I'm working and clearly hear what the processed sound is like as I'm doing it, whether tap dancing, playing the Cajon, sax or whatever.

I like your idea of the free-standing/free-hanging rockwool filled frames hung in front of two or three or the walls -- that was something I thought of, having free-standing "walls" filled with rock wool, and then arranging some free standing bass traps around the room as well (and attached in the upper corners of the room).

Does this help clarify what I'm asking at all?

At first we thought of just building second walls filled with rockwool and surfaced with plasterboard, but it seems would be too reflective for what I'm looking for... such a wall seems more intended for sound isolation than absorption...

...but I don't really know enough about the differences...

...which is why I thought I'd toss this out to the experts. Thanks much for your suggestions and ideas. They're much appreciated.
Bob T
post #5 of 8
For your purposes, any hard surface in the room can be considered highly reflective across the spectrum of sound. As you've noted, with lots of hard surfaces the sounds reflect and persist long after the source of the sound has stopped. This is known as decay, and plays a very large role in shaping your perception of sound in an enclosed space. The goal should be, in my opinion, to allow enough of that reflected sound to persist for you to hear it, but not so much that it overpowers other sounds. At the same time, you want to avoid situations that lead to flutter echo and other position-dependent anomalies.

In contrast to reflective surfaces, most any fibrous material will absorb sound, to some degree. Rock wool, cotton batting, insulation, and even upholstered furniture can all absorb sound and diminish decay times. Here's where it gets a little technical and unintuitive: sound absorption effectiveness is sensitive to wavelength. Low frequency sound has a very long wavelength and can therefore require very large piles of fibrous material for absorption. That matters because if you add thin layers of rock wool to your walls, you only absorb high frequency sound. Low frequencies are allowed to persist and they overwhelm your ability to hear subtler sounds, so as you add absorption to your space, you want to do it in a way that maintains the spectral balance of your music. In regards to the location specific anomalies, mostly that's flutter echo caused by parallel reflective surfaces. I'm sure you can hear a "zing" or spring type of sound if you snap your fingers, clap, or tap in the room now. You can clear that up by making sure that the absorptive material you add is distributed across at least one of any two parallel surfaces - even better if it's on both, but not covering them completely. Since the floor will be hard, make sure you get some on the ceiling.

I suspect that adding absorptive panels like I described - about 4 inches thick - to walls and ceiling will be adequate. You probably won't need any diffusion, but it can be useful. For instance, if you use more and more absorption to control low frequency decay, you can end up absorbing too much high frequency. To correct that, you can add diffusion that will redistribute high frequency sound around the room to restore the spectral balance.

It's nearly impossible to do this without measurement equipment. You can probably use mics and cabling you already have, but you will need software like the program I mentioned earlier.

Fred
Edited by HopefulFred - 8/25/13 at 7:23am
post #6 of 8
Thread Starter 
Okay, I got a copy of Newell's "Recording Studio Design" which I've been reading and which has been very helpful in understanding the qualities of various materials as well as the characteristics / behaviors of different frequencies. It's not yet entirely clear, but definitely the idea of sound absorption/diminution at various frequencies and the various ways to achieve this are getting clearer.

For two walls of the basement we're thinking of making large frames 3-4' across filled with 3-4" thick rockwool are covered in fabric. We'd then "hang" them at slightly varying angles from the ceiling so that the top is perhaps 6-10" from the wall and the base is perhaps 3-4" from the wall, hanging them so they barely touch the floor. Does this seem like a good idea for both absorption and diffusion?

Also, regarding reflectivity and "liveness" the floor will be hard wood and there will probably be about 5-6' of mirrors mounted on a frame filled with 2-3" rockwool that would be mounted on a third wall of the room. One wall would still be mostly untreated concrete with a small window in it and the other wall half-covered with the mirrors, the other half of the wall untreated (and with a door).

I've also downloaded REW and TrueRTA (free version) and I'm bidding on an ECM8000 mic at the moment. I'd like to do a measure at the beginning and then take measurements as we work to see what differences it makes.

If you have any thoughts on any of this, I would be grateful to hear them.

Thanks for your help and attention to this, you definitely pointed me in the right direction.

All the best, Bob T
post #7 of 8
sounds like you are headed down the right path with treating your room, after watching a couple of your taped video performances and reading about your goals the thought jumped into my head about going past just the shotgun microphones. What about putting contact microphones under the wood dance floor, also what about building some platforms of various internal sizes (tuning) to tap on a creating various sounds for your mixes.

Lastly you might want to look into the Behringer feedback destroyer unit to tame the feedback you say you experience. It employees a notch filter to cut the frequency of the feedback.
post #8 of 8
Thread Starter 
Hmmm, some very good ideas, now you've really got me thinking beyond just the room...

Lavalier mics attached to the shoes with the wire running from the sender unit down the inside of the pants have been the way to go for the past several years.

The cardioid lavaliers are much easier and more effective to use and control than using contact / PZM mics, since mics of any sort placed under the floor have pickup patterns that tend to be too localized so that volume and tone vary widely depending on where you are on the floor as you tap.

Also with under-floor mics having a portable floor is difficult. I often use two 3'x4' "roll-up" tap floors set end to end, with slats 3' floor-wide by 2" per slat, the slats glued to a thick canvas back, so they roll up and roll out quite easily, and with these contact mics are not an option.

I spent over $200 each for the shotgun mics, but for some reason I've been reluctant to spend an equal amount for the lavalier -- which I hadn't really thought about until you said something. I'll have to do some research and see what is commonly used (Savion Glover and Broadway shows use these things all the time), and see what it would cost. Thanks for the nudge...

And yeah, the whole idea of modifying the sound of the taps (after 5 minutes it all sounds the same to an audience) is to use guitar processors, delays, reverbs, synth envelope followers, etc to vary the tap sounds between (and sometimes within) pieces, mostly using midi control through a foot controller. Which I find exciting, especially since I can also process Cajon sounds to set up a live looped drum track, tuba and sax for various lines, etc.

Hmmm... I have an FBQ2496 and also a Behringer Shark, but I've been reluctant to use them in rehearsal since it means I'm hacking out a good portion of my frequency response, thus skewing whatever adjustments I'm testing with the audio processing at that moment. I do expect to use the FBQ2496 for gigs, so I can adjust my sound output to the room, however.

Good questions, good ideas... hmm, any more thoughts and brainstorming would be very welcome.

Okay, nowI have to go on the internet now and do some research about what kind of lavaliers are used by the major tap dancers in shows.

Thanks much!
Bob T
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