Hello,
Can anyone recommend a design for a bass trap that would reduce frequencies in the range 55Hz-1001Hz?
Perhaps a Tube Trap? What size would it need to be? How can the design and specs such as dimensions; insulation thickness/flow specs or distance from corners be required for this Tube Trap?
Are there any other possibilities?
thx so much,
Can anyone recommend a design for a bass trap that would reduce frequencies in the range 55Hz-1001Hz?
Perhaps a Tube Trap? What size would it need to be? How can the design and specs such as dimensions; insulation thickness/flow specs or distance from corners be required for this Tube Trap?
Are there any other possibilities?
thx so much,
More than just an octave (x2), he's saying he has an entire decade(x10) that's wrong. Twice that even.
If it was 55 and a decade above that wouldn't surprise me, you're right in modal range, but all the way to 1000? Sounds to me like a setup or speaker issue.
I agree with Turk182, some measurements and more info on room size, equipment, and setup is in order.
If it was 55 and a decade above that wouldn't surprise me, you're right in modal range, but all the way to 1000? Sounds to me like a setup or speaker issue.
I agree with Turk182, some measurements and more info on room size, equipment, and setup is in order.
i think the text of the post contains a typo...and yeah i could be wrong but the thread title seems more likely....but all is quiet from the OP.
It will be hard to make 1 absorber which covers the range 55 to 110 Hz, that's 1 octave. It needs to be very thick in that case, 300 mm / 12" and upwards.
In general, the lower in frequency the harder with a wide band in frequency (Hz). Think in wavelengths! 55 Hz = 6,25 m / 20,56 feet, 15 Hz down = 40 Hz and wave length is 8,60 m / 24,7 feet. Quite a difference! 110 Hz = 3,13 m / 10,3 feet. 15 Hz down and 95 Hz = 3,62 m / 11,9 feet. 15 Hz difference in both cases but the change in wave length is huge in comparison.
I would go for 2 helmholtz absorbers which preferably overlap in their effective absorbtion range. "Effective" I would see as absorbtion factor 0,8 and above. (0,5 means a change of 3 dB, not very much). If you look at your wave lengths it should be obvious they also need to be as large in length and width as is practicable for you. You don't influence a 6,25 m wave much or at all with a small object.
In general: Using a "thin" perforated plywood / MDF instead of a "thick" one tends to make the helmholtz more broadband but at the same time less effective at a certain frequency. There should an airgap between the backside of the plywood sheet and the insulation inside. Suitable air gap can be the same as the hole diameter or larger. It is advantageous for maximum absorbtion to compartmentalize the inside of the Helmholtz. Distance between holes should be a lot larger than the hole diameter. By combining hole diameter, length between holes, air gap and the airflow resistivity of the insulation inside you can "tailor make" your absorber for a certain frequency range. In the picture used airflow resistivity is 7000 Pa.s/m². that would equate to the fluffiest most light weight attic insulation you can findd. A high airflow resistivity is not necessarily better, on the contrary often, but if total allowed thickness is small, say 50-100 mm / 2-4", one should go up in airflow resistivity, 20-30 000 could be better.
In enclosed picture there are 2 absorbers which almost overlap. On Multi-layer Absorber Calculator you can calculate with other dimensions. If you are using American units, calculate them to 2 decimals for entered mm-units. To turn out tuned as wanted versus theory it is very picky with measurements and construction. It should be an airtight box with a perforated facing sheet. If the box leaks, it will be as functinal as a punctured balloon, -no fun. Do not have a fabric close to the holes, that will restrict the airflow through the holes and the absorber may turn out useless. For widest broadband and highest absorbtion in combinations, you should strive for "medium damping". "High damping" will mean max absorbtion but within a narrow band of frequencies. "Low damping" is just that, low damping of the frequencies.
In general, the lower in frequency the harder with a wide band in frequency (Hz). Think in wavelengths! 55 Hz = 6,25 m / 20,56 feet, 15 Hz down = 40 Hz and wave length is 8,60 m / 24,7 feet. Quite a difference! 110 Hz = 3,13 m / 10,3 feet. 15 Hz down and 95 Hz = 3,62 m / 11,9 feet. 15 Hz difference in both cases but the change in wave length is huge in comparison.
I would go for 2 helmholtz absorbers which preferably overlap in their effective absorbtion range. "Effective" I would see as absorbtion factor 0,8 and above. (0,5 means a change of 3 dB, not very much). If you look at your wave lengths it should be obvious they also need to be as large in length and width as is practicable for you. You don't influence a 6,25 m wave much or at all with a small object.
In general: Using a "thin" perforated plywood / MDF instead of a "thick" one tends to make the helmholtz more broadband but at the same time less effective at a certain frequency. There should an airgap between the backside of the plywood sheet and the insulation inside. Suitable air gap can be the same as the hole diameter or larger. It is advantageous for maximum absorbtion to compartmentalize the inside of the Helmholtz. Distance between holes should be a lot larger than the hole diameter. By combining hole diameter, length between holes, air gap and the airflow resistivity of the insulation inside you can "tailor make" your absorber for a certain frequency range. In the picture used airflow resistivity is 7000 Pa.s/m². that would equate to the fluffiest most light weight attic insulation you can findd. A high airflow resistivity is not necessarily better, on the contrary often, but if total allowed thickness is small, say 50-100 mm / 2-4", one should go up in airflow resistivity, 20-30 000 could be better.
In enclosed picture there are 2 absorbers which almost overlap. On Multi-layer Absorber Calculator you can calculate with other dimensions. If you are using American units, calculate them to 2 decimals for entered mm-units. To turn out tuned as wanted versus theory it is very picky with measurements and construction. It should be an airtight box with a perforated facing sheet. If the box leaks, it will be as functinal as a punctured balloon, -no fun. Do not have a fabric close to the holes, that will restrict the airflow through the holes and the absorber may turn out useless. For widest broadband and highest absorbtion in combinations, you should strive for "medium damping". "High damping" will mean max absorbtion but within a narrow band of frequencies. "Low damping" is just that, low damping of the frequencies.
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Add a DSP - measure and correct.
If it should be really good - add minimum 2 subs 🙂
There's more - I simplified - obviously 😉 But building bass traps - will become huge and unpractical.
A couple of full size StudioTips SuperChunks? That should be a good start. Easy to DIY too. Teddy bears in front of them should help with the lower growling frequencies. Seriously though, the Super Chunks are the direction I'm considering. Google it.
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Bass Trap Design
To the OP: F. Alton Everest has a very good section on absorber design in "Master Handbook of Acoustics", including formulae. Also, although probably much harder to find, "Acoustical Designing in Architecture" by Vern Knudsen and Cyril Harris goes into good depth on the topic.
To the OP: F. Alton Everest has a very good section on absorber design in "Master Handbook of Acoustics", including formulae. Also, although probably much harder to find, "Acoustical Designing in Architecture" by Vern Knudsen and Cyril Harris goes into good depth on the topic.
I read Master Handbook of acoustics twice and can concur on the bass trap designs there but I sincerely missed out on the teddy bears, great tip 😛