You have car audio guys listening to anything between 110-150 dB SPL of low bass. These guys don't seem to develop hearing problems. I agree with the theory that bass need to be VERY VERY loud to damage hearing. I guess it follows the Fletcher curves...
Same thing about very high frequency stuff. Not much people damaged their hearing by listening to metal tweeters with a 20 dB peak at 40 kHz...
Same thing about very high frequency stuff. Not much people damaged their hearing by listening to metal tweeters with a 20 dB peak at 40 kHz...
We had a course in university about acoustics, hearing protection, how damage to hearing develops etc. It was pretty interesting and quite useful for planning how to protect my ears from noise that can do damage.
It wasn't necessarily directly A-weighting curve the curve for the capability to damage, but the sensitivity to damage was quite similar curve, the low bass was least of the problem on the scale and worst was mid frequencies, and the second worst was upper high frequencies and then high frequencies. Many people work in factories and get continuous infrasounds at very high SPL despite of hearing protection and never develop hearing damage (and they don't even think that it is noise, because the lowest bass really is vibration the body senses rather than is heard by the ear). Then others work on airfields near to jet engines (which produce very peaky mid and high frequencies) and without protection, they get damage to mid frequencies to their ears. Extremely loud low bass can cause mechanical damage to auditory membrane (eardrum), when its Xmax gets exceeded, but that occurs usually only with being near a cannon or something alike which produces 180 dB SPL. No subwoofer produces that high SPL, especially not my Tumult. The low bass can be loud despite it is not sensed loud - for example how many of us have thought that slamming a car door makes (if I remember it at all correctly) 140 dB peak at 5 Hz. The low frequency amount aboard a bus, truck or even on a family car is also a quite high. How about firing a gun - even with (double) hearing protection, the ears are subject to quite high low frequency peak because the hearing protectors do not protect from low frequencies (other than active noise cancellation hearing protectors). If you go to a factory where is a sign "The noise level here is over 85 dB(A), using hearing protection is mandatory", the noise level is measured with A-weighting curve and its dangerous is based on the A-weighted noise. Same applies to movie theaters, they seem to be usually below 85 dB(A) despite linear dB peaks can be over 110 dB (in other words, if low bass is taken into account). However, the noise there too is measured with A-weighting curve and not considered harmful because the mid frequencies the ear is the most sensitive remain in not that harmful for average person values (<85dB(A)). Disco music is more harmful than movies, not because of low bass (it lacks lowest bass actually), but because of the high energy on the mid frequencies, and the A-weighted continuous noise level is rather high.
Our airplane produces a lot more low frequency vibration than our Tumult can ever do with the highest peak. Still, I consider it safe even with only the passive noise cancellation headsets. For convenience we are planning to get the active noise cancellation headsets which suppresses also bass, but I don't think the bass dosage from that is really that dangerous. Also high amount of noise has the tendency to cause hearing damage to its frequency - in other words, if you listen to very high SPL 1 kHz, it is quite likely that the 1 kHz area will be damaged in your hearing. You still have the capability to hear bass and high frequencies, actually it is the most common type of hearing damage that mid frequencies are damaged and bass and treble can be heard without problems, for example my mom has just that kind of hearing damage and it causes trouble for hearing voice.
The ear system is not very simple though, and I can't guarantee that a very high SPL to some certain frequency wouldn't cause damage to other frequencies, but the above is basically what was told on the course back in 1994 or so I was participating it and it have worked for me pretty well - my ears are in a relatively good condition and I always protect my hearing in disco, factories, using noisy machines/tools etc. (including the lawn mover which produces over 95 dB(A) - measured).
It wasn't necessarily directly A-weighting curve the curve for the capability to damage, but the sensitivity to damage was quite similar curve, the low bass was least of the problem on the scale and worst was mid frequencies, and the second worst was upper high frequencies and then high frequencies. Many people work in factories and get continuous infrasounds at very high SPL despite of hearing protection and never develop hearing damage (and they don't even think that it is noise, because the lowest bass really is vibration the body senses rather than is heard by the ear). Then others work on airfields near to jet engines (which produce very peaky mid and high frequencies) and without protection, they get damage to mid frequencies to their ears. Extremely loud low bass can cause mechanical damage to auditory membrane (eardrum), when its Xmax gets exceeded, but that occurs usually only with being near a cannon or something alike which produces 180 dB SPL. No subwoofer produces that high SPL, especially not my Tumult. The low bass can be loud despite it is not sensed loud - for example how many of us have thought that slamming a car door makes (if I remember it at all correctly) 140 dB peak at 5 Hz. The low frequency amount aboard a bus, truck or even on a family car is also a quite high. How about firing a gun - even with (double) hearing protection, the ears are subject to quite high low frequency peak because the hearing protectors do not protect from low frequencies (other than active noise cancellation hearing protectors). If you go to a factory where is a sign "The noise level here is over 85 dB(A), using hearing protection is mandatory", the noise level is measured with A-weighting curve and its dangerous is based on the A-weighted noise. Same applies to movie theaters, they seem to be usually below 85 dB(A) despite linear dB peaks can be over 110 dB (in other words, if low bass is taken into account). However, the noise there too is measured with A-weighting curve and not considered harmful because the mid frequencies the ear is the most sensitive remain in not that harmful for average person values (<85dB(A)). Disco music is more harmful than movies, not because of low bass (it lacks lowest bass actually), but because of the high energy on the mid frequencies, and the A-weighted continuous noise level is rather high.
Our airplane produces a lot more low frequency vibration than our Tumult can ever do with the highest peak. Still, I consider it safe even with only the passive noise cancellation headsets. For convenience we are planning to get the active noise cancellation headsets which suppresses also bass, but I don't think the bass dosage from that is really that dangerous. Also high amount of noise has the tendency to cause hearing damage to its frequency - in other words, if you listen to very high SPL 1 kHz, it is quite likely that the 1 kHz area will be damaged in your hearing. You still have the capability to hear bass and high frequencies, actually it is the most common type of hearing damage that mid frequencies are damaged and bass and treble can be heard without problems, for example my mom has just that kind of hearing damage and it causes trouble for hearing voice.
The ear system is not very simple though, and I can't guarantee that a very high SPL to some certain frequency wouldn't cause damage to other frequencies, but the above is basically what was told on the course back in 1994 or so I was participating it and it have worked for me pretty well - my ears are in a relatively good condition and I always protect my hearing in disco, factories, using noisy machines/tools etc. (including the lawn mover which produces over 95 dB(A) - measured).
You don't need to spend that much to get that much power. The Behringer EP2500 produces 2.4kw briged into 4 ohms (yes it is 2 ohm stable) and in Finland RRP = 365 euro ie you should be able to get it for less than the amp you have now as pro stuff never goes for RRP.
This is the amp I use. It has 2 downsides to it:
1. no relay mute circuit to disconnect outputs after its turned off so you can get thumps amplified through the system 30 secs after it has been turned off - this is not a big deal
2. fairly noisy fan - not very difficult to deal with and something you have to live with in order to get this much power without spending about 8x as much on something like the Crown K2
Some pictures about finishing (gallery link):
http://www.katix.org/gallery2/main.php?g2_view=core:ShowItem&g2_itemId=1565
I added some carbon fiber & glass fiber composite reinforcement to the opening (used SP Systems Ampreg 20 epoxy system). Actually it leaked before, it appears, it can do more powerful low bass than before. The back side is finished (and thus sealed) with epoxy too and so is the interior. Works perfectly.
It is the best subwoofer I have ever had. It appears it can now produce equal feeling (at home theater) than the (supposedly Servodrive) subs did in Jean-Michel Jarre's concert in Helsinki back in 1997.
http://www.katix.org/gallery2/main.php?g2_view=core:ShowItem&g2_itemId=1565
I added some carbon fiber & glass fiber composite reinforcement to the opening (used SP Systems Ampreg 20 epoxy system). Actually it leaked before, it appears, it can do more powerful low bass than before. The back side is finished (and thus sealed) with epoxy too and so is the interior. Works perfectly.
It is the best subwoofer I have ever had. It appears it can now produce equal feeling (at home theater) than the (supposedly Servodrive) subs did in Jean-Michel Jarre's concert in Helsinki back in 1997.
1# Fiberglass and epoxy is quite easy to work with. The technique is normally used in composite airplane construction. It is critical that you mix resin and hardener exactly per instructions, but by following that, it is very easy. You need some protection though: gas mask and nitrile gloves (green). Handling epoxy without protection causes epoxy allergy which can develop as bad as asthma. Do not try to use scissors to cut fiberglass, it doesn't work that way. Buy a rotary cutter instead. Also epoxy roller is a good investment (actually couple of them as you will propably ruin some of them with cured epoxy). The idea is just to wet the glass fiber cloth with the mixed epoxy (on table on top of some plastic), put the cloth where you want to put it and then roll with the roller to squeeze excess epoxy away and to make sure that it takes. You may also need to buy glass micro balls, they can be used below the glass fiber to make it take better to e.g. wood, foam or whatever. Normally composite is built as sandwitch so that you cover foam with glass fiber. However, in loudspeaker construction, light weight is not the goal, so also wood can be used as the core material. You can build a composite loudspeaker this way and end up with a very rigid (and well sealed) speaker.
2# If you want to try some glass fiber stuff, I highly recommend buying real epoxy, like SP Systems Ampreg 20/22 or MGS Systems L285 or West System brand epoxy. Polyester resins are ugly stuff that have weak properties and the MEK hardener is very toxic and causes foam to melt. With wood as core material, it doesn't cause the wood to melt, but it still is really ugly stuff. It even melts your gloves from your hands, is very sticky etc... Real epoxy, in addition it being a lot stronger, is also a lot nicer to handle. It doesn't melt plastic, it is easy to wet the cloth on top of plastic bag for example. Epoxy is a lot more expensive than polyester or vinylester resins, but in loudspeaker stuff you don't need that large amounts of it that it should prove to be an issue. Epoxy is not sold on normal hardware stores, at best, they sell polyester. But don't buy polyester. I have a 20 kg can of polyester at home and don't know what I would do with it, I do not want to touch it any longer...
3# I used them mainly because I did an error in the construction: I sawed too large hole for the driver to the front panel, some screws did not take to the wood and it resulted (supposedly) some leakage. Now with the glass fiber ring in the opening, the screws are tight and the driver is tightly in the front baffle. Also I suspected some leakage from the back wall, so I used epoxy there too to seal the potential leaks.
Those of you that live in USA, can buy epoxy, fiberglass and other supplies from Aircraft Spruce: http://www.aircraftspruce.com/
They sell for example the MGS epoxy.
2# If you want to try some glass fiber stuff, I highly recommend buying real epoxy, like SP Systems Ampreg 20/22 or MGS Systems L285 or West System brand epoxy. Polyester resins are ugly stuff that have weak properties and the MEK hardener is very toxic and causes foam to melt. With wood as core material, it doesn't cause the wood to melt, but it still is really ugly stuff. It even melts your gloves from your hands, is very sticky etc... Real epoxy, in addition it being a lot stronger, is also a lot nicer to handle. It doesn't melt plastic, it is easy to wet the cloth on top of plastic bag for example. Epoxy is a lot more expensive than polyester or vinylester resins, but in loudspeaker stuff you don't need that large amounts of it that it should prove to be an issue. Epoxy is not sold on normal hardware stores, at best, they sell polyester. But don't buy polyester. I have a 20 kg can of polyester at home and don't know what I would do with it, I do not want to touch it any longer...
3# I used them mainly because I did an error in the construction: I sawed too large hole for the driver to the front panel, some screws did not take to the wood and it resulted (supposedly) some leakage. Now with the glass fiber ring in the opening, the screws are tight and the driver is tightly in the front baffle. Also I suspected some leakage from the back wall, so I used epoxy there too to seal the potential leaks.
Those of you that live in USA, can buy epoxy, fiberglass and other supplies from Aircraft Spruce: http://www.aircraftspruce.com/
They sell for example the MGS epoxy.
Nice work Karoliina!
I love how pretty your enclosure looks. SOON, I will be posting some pictures of what I'm doing with my Tumult. I'm going for 6cubic feet(170L) tuned to 16hz via two Stryke PR-18's. I will be powering with the ADA1200 which will hopefully arrive next week! I dont think my enclosure will be as pretty as yours though. I haven't yet decided on a finish, but the box itself is going to be built with 3/4" MDF. I'm going double thick on the exterior and doing pretty extensive bracing. My guess is that it will weigh over 200lbs when all is said and done, kinda hard to move. How do you move yours?
I love how pretty your enclosure looks. SOON, I will be posting some pictures of what I'm doing with my Tumult. I'm going for 6cubic feet(170L) tuned to 16hz via two Stryke PR-18's. I will be powering with the ADA1200 which will hopefully arrive next week! I dont think my enclosure will be as pretty as yours though. I haven't yet decided on a finish, but the box itself is going to be built with 3/4" MDF. I'm going double thick on the exterior and doing pretty extensive bracing. My guess is that it will weigh over 200lbs when all is said and done, kinda hard to move. How do you move yours?
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Dont use epoxy resins if....
Just an FYI for all of you in hot states like Texas or those who intended on making a SEALED fiberglass enclosure. Do not use epoxy resin. Epoxy resin will begin to melt in the range of 135(slow cure)- 160 (fast cure) degrees unless you get high temperature resin which requires specific cure instructions, such-as oven curing. I learned of this AFTER I purchased two gallons of epoxy resin. I just wanted to save a few of those more fortunate souls. Yes, in Texas summer your car can reach these temperatures out in the sun. As for a sealed enclosure, it can reach up to 80 C or 176 F inside of the box due to heat from the magnet. I don't think that you want epoxy dripping on your subwoofer. Sorry, but you must use either Vinylester (my choice) or Polyester for a custom sealed enclosure. If you live in a colder state you can use Epoxy resin for a sealed enclosure, but only if you reverse the subwoofer (magnet out). I can't do this with my woofers as the design of the mounting ring does not allow it.
Just an FYI for all of you in hot states like Texas or those who intended on making a SEALED fiberglass enclosure. Do not use epoxy resin. Epoxy resin will begin to melt in the range of 135(slow cure)- 160 (fast cure) degrees unless you get high temperature resin which requires specific cure instructions, such-as oven curing. I learned of this AFTER I purchased two gallons of epoxy resin. I just wanted to save a few of those more fortunate souls. Yes, in Texas summer your car can reach these temperatures out in the sun. As for a sealed enclosure, it can reach up to 80 C or 176 F inside of the box due to heat from the magnet. I don't think that you want epoxy dripping on your subwoofer. Sorry, but you must use either Vinylester (my choice) or Polyester for a custom sealed enclosure. If you live in a colder state you can use Epoxy resin for a sealed enclosure, but only if you reverse the subwoofer (magnet out). I can't do this with my woofers as the design of the mounting ring does not allow it.
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