Not done a sinewave sweep yet, but far as I know there's nothing else it could be in the near vicinity of the subs.
It also sounds like it's coming from the subs themselves, however the other two subs don't have any rattle though and far as I know all are the same age and have been used the same.
It also sounds like it's coming from the subs themselves, however the other two subs don't have any rattle though and far as I know all are the same age and have been used the same.
For MUSIC, there is practically NO NEED for response below 40Hz. If those subs are ported, make sure they are tuned to 40Hz. EQ any big lumps above 40Hz and cut the response below that as much as you can.
Your experience with the JBL 4520s bears this out.
Trying to get a noise below 40Hz usually seriously compromises the sound above. To get that last octave to sound good, you need DOUBLE THE BOXES which will have to be specially designed and DOUBLE THE AMPS
You got so much advice on placement (mostly dodgy) that I'll keep out of that arena 😊
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https://www.mixcloud.com/darrel-wipfel/monday-ride-out-mix/
Some of the music I play, I've listened to on my home stereo and I hear bass notes below 40Hz that I do not hear on the rink system.
For instance a song like this.
It's got content at the start that a sub that cannot go below 40Hz will not reproduce properly.
Now a lot of the older skate music didn't always have lots of bass below 40Hz though. The newer stuff does, however.
Some of the music I play, I've listened to on my home stereo and I hear bass notes below 40Hz that I do not hear on the rink system.
For instance a song like this.
It's got content at the start that a sub that cannot go below 40Hz will not reproduce properly.
Now a lot of the older skate music didn't always have lots of bass below 40Hz though. The newer stuff does, however.
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So you have an unused sub sitting right next to one that is still in use? We covered this way back in this thread if I'm not mistaken... you can't do that it effectively unloads the driver that is still in use which totally messes up the output response and makes it much easier to push the driver in use into over excusrion. The "rattling" you hear could be the drivers voice coil bouncing off the backplate. If you're not going to physically remove the unused sub it's leads have to be shorted to prevent the above problem.
Doubt it's the voice coil bouncing off the back plate as I know what that sounds like from hearing speakers do that at home and I know the driver could not survive several hours at an average power of 1200 watts with the voice coil bouncing off the back plate.
Even though the subs are on their side with the horn mouths side by side it will unload the in use driver?
Next Friday I'll see if I can record what the not in use driver sounds like.
The subs are used once or twice a week at near maximum output from a pair of bridged QSC RMX2450A amps with two subs per amp. The limiters are on which will not allow the amp to go above it's maximum of 2400 watts into 4 ohms bridged and am careful to not feed so much signal that the clip lights turn on.
The other two subs sound fine though.
I need to figure how to open the cabinets without damage so that I can see if anything is loose such as driver mounting screws, wood braces ETC...
Even though the subs are on their side with the horn mouths side by side it will unload the in use driver?
Next Friday I'll see if I can record what the not in use driver sounds like.
The subs are used once or twice a week at near maximum output from a pair of bridged QSC RMX2450A amps with two subs per amp. The limiters are on which will not allow the amp to go above it's maximum of 2400 watts into 4 ohms bridged and am careful to not feed so much signal that the clip lights turn on.
The other two subs sound fine though.
I need to figure how to open the cabinets without damage so that I can see if anything is loose such as driver mounting screws, wood braces ETC...
I'm not sure reproducing the stuff on those tracks below 40Hz will add to the musical experience.
But if you want to do it with the same quality as the JBL 4520s above 40Hz, you will need to double the number of subs (of the same size) and amps . They will need to be specially designed to do so.
It might add to it for those who know the music and know what's missing that should be there.
Thing is I don't think we're getting the -3dB of 35Hz the subs are capable of and I think it's due to where the subs are located.
Perhaps putting all four side by side at one end of the rink would be better.
At one point I was getting a peak at 59Hz which likely is due to the sub placement.
Thing is I don't think we're getting the -3dB of 35Hz the subs are capable of and I think it's due to where the subs are located.
Perhaps putting all four side by side at one end of the rink would be better.
At one point I was getting a peak at 59Hz which likely is due to the sub placement.
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Yes, if you stand there and watch the un-used driver it will be moving in and out, Short the leads of the driver right at the box with a little jumper cable in a Speakon plug if that is how they are equipped, and that movemnt will stop.
I'll try that.
The subs also have 1/4" jacks which I don't quite understand since they are rated at 1200 watts RMS. Might just be easier to wire up a 1/4" plug as I don't have any extra speakon plugs.
The subs also have 1/4" jacks which I don't quite understand since they are rated at 1200 watts RMS. Might just be easier to wire up a 1/4" plug as I don't have any extra speakon plugs.
Yeah 1/4" plugs are sketchey at this power level.. it's a holdover from the '80's that works OK while the jack is fully inserted but there is high potential to short the amplifier outputs while inserting or removing it.. which is really bad. A 1/4" connector doesn't have a particularly high power rating either and really should not be used with a sub like this, but people are generally not aware of this.
However it is really easy to build a little shorting plug with that connector so no need to worry about speakon connectors.
However it is really easy to build a little shorting plug with that connector so no need to worry about speakon connectors.
The skating facility that used to be had some interesting equipment at one point.
Looked like some 80s Peavey amps and a few ancient 24” drivers and some other cabinets that were in a pile in a far corner. It sounded good.
That was replaced with a series of many small boxes, each with a single 8”, and an absolutely horrible tweeter.
I had some fun conversations with the resident dj while the older system was still there. After the new system went in I started wearing earplugs, pretty sure the guy noticed too, oh well, he had to know it sucked…
Never knew what the newer amps were.
That’s a good plan to check out the cabinets for anything loose, was going to suggest that.
Looked like some 80s Peavey amps and a few ancient 24” drivers and some other cabinets that were in a pile in a far corner. It sounded good.
That was replaced with a series of many small boxes, each with a single 8”, and an absolutely horrible tweeter.
I had some fun conversations with the resident dj while the older system was still there. After the new system went in I started wearing earplugs, pretty sure the guy noticed too, oh well, he had to know it sucked…
Never knew what the newer amps were.
That’s a good plan to check out the cabinets for anything loose, was going to suggest that.
While looking for cabinet disassembly instructions I found this.
https://soundforums.net/community/threads/yorkville-ls1208-woofer-upgrade.212762/
Here's the driver mentioned
https://www.parts-express.com/B-C-18TBW100-18-Professional-Subwoofer-8-Ohm-294-6007?quantity=1
If the driver does extend the low end response of the sub that would be good.
I looked at the pictures and disassembly to access the driver is a single panel, however the cabinets need to be moved from their current location to access that panel though. https://www.dropbox.com/scl/fo/nmml3781l6z1ckkj045av/h?dl=0&e=1&rlkey=2lxsgwc14h5i88zlv8i41swk6
I might try to use that fact to get the cabinets moved to by the DJ booth.
Also makes me wonder if the screws holding that panel on are loose as the sound I hear does sound like wood vibrating.
That said if the seal of the panel is compromised, it could possibly damage the driver if ran constantly at near maximum power, right?
https://soundforums.net/community/threads/yorkville-ls1208-woofer-upgrade.212762/
Here's the driver mentioned
https://www.parts-express.com/B-C-18TBW100-18-Professional-Subwoofer-8-Ohm-294-6007?quantity=1
If the driver does extend the low end response of the sub that would be good.
I looked at the pictures and disassembly to access the driver is a single panel, however the cabinets need to be moved from their current location to access that panel though. https://www.dropbox.com/scl/fo/nmml3781l6z1ckkj045av/h?dl=0&e=1&rlkey=2lxsgwc14h5i88zlv8i41swk6
I might try to use that fact to get the cabinets moved to by the DJ booth.
Also makes me wonder if the screws holding that panel on are loose as the sound I hear does sound like wood vibrating.
That said if the seal of the panel is compromised, it could possibly damage the driver if ran constantly at near maximum power, right?
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I've identified what the problem is.
I was able to get at the panel that removes and I hit it. Heard a vibration that shouldn't be there.
I then went to one of the good subs and did the same. No vibration that shouldn't be there.
So that tells me one sub has the wood attached to the back of that panel loose and the other one with the worse rattle likely had it fall off and is hitting against the driver so it's good I have it unplugged.
I did not have time to build a shorting plug though.
Now I just gotta get them to pull the subs so that I can pull the panels and fix them. Not sure how long that will take. Been needing some new tops for three years and only got three a few months ago and three more should be purchased at any time now.
I was able to get at the panel that removes and I hit it. Heard a vibration that shouldn't be there.
I then went to one of the good subs and did the same. No vibration that shouldn't be there.
So that tells me one sub has the wood attached to the back of that panel loose and the other one with the worse rattle likely had it fall off and is hitting against the driver so it's good I have it unplugged.
I did not have time to build a shorting plug though.
Now I just gotta get them to pull the subs so that I can pull the panels and fix them. Not sure how long that will take. Been needing some new tops for three years and only got three a few months ago and three more should be purchased at any time now.
So due to the one sub having the bad rattle (been unplugged at least a year) and the other sub on the same amp starting to rattle, I turned the amp off.
Been listening to the music for about an hour and with just these two subs on the bass sounds better. Possibly due to the bass coming from one location..
Been listening to the music for about an hour and with just these two subs on the bass sounds better. Possibly due to the bass coming from one location..
That is just two subs running at a max of 2400 watts and the whole rink has decent bass.
I'm pretty sure there was some cancellation at certain frequencies and maybe boost at other frequencies with the four subs running placed where they are.
Probably explains why at one point it sounded like the subs had a higher output at 59Hz which is why I thought the subs weren't all that good.
I'm pretty sure there was some cancellation at certain frequencies and maybe boost at other frequencies with the four subs running placed where they are.
Probably explains why at one point it sounded like the subs had a higher output at 59Hz which is why I thought the subs weren't all that good.
Yes we covered that early in this thread so it's good that you have had the chance to hear this for yourself. Generating good bass indoors is a complex issue.