I think my sub box needs more bracing

[MrBoat]

I have no idea how powerful your subwoofer is or the design criteria of the box. But there are always options.

 

[yonyz]

It's a 300w amp with an Infinity 1260w driver. It's plenty powerful, but not at all when compared against the monsters in this forum.

I still don't know how to get the driver out, though.

 

[MrBoat]

It's a 300w amp with an Infinity 1260w driver. It's plenty powerful, but not at all when compared against the monsters in this forum.

I still don't know how to get the driver out, though.

I make a hook out of stiff wire and then cut off the hook close to the wire so that it grabs under the screw hole and I pull a little on each hole until it starts to pull free if it is stuck with fresh paint. The wire I use is about 3mm. Another way is to find a coarse thread screw that is slightly larger that the screw holes, and letting that grab it so you have something to pull on.

Perhaps another way is to loosen all of the screws part way, and turning the woofer up and let it shake itself free to where you can grab it.

 

[yonyz]

Hey guys, I haven't got around to buying the pieces of wood but, there's a more urgent problem with the sub which became consistent in the past week or so. When really low frequency is played (I guess below 20hz or so), the driver itself makes a very noticeable noise that really worries me. I checked and it's not loose at all, and based on what I've read it may be due to hitting the X-max (hopefully not the x-mech ), so I wonder what I'm supposed to do to make sure it doesn't try to reproduce the frequencies that it cannot reproduce properly/safely. The vent is tuned to 22hz, but the cone excursion graph on WinISD Pro shows that it reaches 12.9mm excursion at 19.5hz. X-max for this driver is at 13mm, so I think cutting it off at 19.5hz should be good. But just how do I do that? And how can I be sure I didn't ruin the driver for good?

 

[lovinthehd]

It's a 300w amp with an Infinity 1260w driver. It's plenty powerful, but not at all when compared against the monsters in this forum.

I still don't know how to get the driver out, though.

Hey guys, I haven't got around to buying the pieces of wood but, there's a more urgent problem with the sub which became consistent in the past week or so. When really low frequency is played (I guess below 20hz or so), the driver itself makes a very noticeable noise that really worries me. I checked and it's not loose at all, and based on what I've read it may be due to hitting the X-max (hopefully not the x-mech ), so I wonder what I'm supposed to do to make sure it doesn't try to reproduce the frequencies that it cannot reproduce properly/safely. The vent is tuned to 22hz, but the cone excursion graph on WinISD Pro shows that it reaches 12.9mm excursion at 19.5hz. X-max for this driver is at 13mm, so I think cutting it off at 19.5hz should be good. But just how do I do that? And how can I be sure I didn't ruin the driver for good?

Turn the volume down is your immediate choice. What amp and dsp do you have for the sub?

 

[yonyz]

Turn the volume down is your immediate choice. What amp and dsp do you have for the sub?

Bash 300s. Volume level is reference, calibrated with audyssey.

The amp of the sub is at half volume, and audyssey set the sub level to -12. This driver should be able to handle 300w safely.

 

[lovinthehd]

Bash 300s. Volume level is reference, calibrated with audyssey.

The amp of the sub is at half volume, and audyssey set the sub level to -12. This driver should be able to handle 300w safely.

Your avr can set the sub level to less than -12? In my avrs -12 is the lower limit and would be indicating the gain on the sub amp was set too high; you should lower the gain on the bash and rerun Audyssey (unless your maximum is -15 or something, then no harm).

The "manual" for that amp only indicates some user adjustable bass boost.

 

[yonyz]

Your avr can set the sub level to less than -12? In my avrs -12 is the lower limit and would be indicating the gain on the sub amp was set too high; you should lower the gain on the bash and rerun Audyssey (unless your maximum is -15 or something, then no harm).

The "manual" for that amp only indicates some user adjustable bass boost.

Good info! Minus 12 is the limit indeed. However, now I also have Dirac Live running, which further lowered the LFE channel by minus 0.4. The problem is persistent, though.

My PC is the only source of audio, there must be a software solution to this. Maybe through JRiver Media Center itself?

 

[lovinthehd]

That Dirac further lowered it still doesn't resolve that likely your sub's gain is likely at too high a level (and therefore not calibrated to reference and running hot). I'd lower the gain on the sub and rerun Audyssey and Dirac.

I'm not familiar with Jriver but understand it has pretty comprehensive dsp; look to see if it can set a high pass filter in the frequency range around tuning.

 

[yonyz]

That Dirac further lowered it still doesn't resolve that likely your sub's gain is likely at too high a level (and therefore not calibrated to reference and running hot). I'd lower the gain on the sub and rerun Audyssey and Dirac.

I'm not familiar with Jriver but understand it has pretty comprehensive dsp; look to see if it can set a high pass filter in the frequency range around tuning.

Audyssey is no longer ON, Dirac negates the need for it. The sub level setting on the receiver is separate, though.

I don't see why Dirac won't fix the sub volume, though. Among other things, it balances the volume of all speakers at the seating position, including the sub. And even if it's still above reference volume, it's something this driver/amp/cabinet combo should be able to handle rather easily.

I will now run some test tones with REW to see at what frequency my sub starts making noises, in order to find the right frequency for the cut off filter.

Edit: OK, interesting fact. I used the Generator tool of REW, and it was fine down to 40hz. Then I checked 30hz and I heard it, so I leaned over the sub to hear it better and then it was much quieter. So I got up and it was louder! I then leaned over it again, applying pressure to the top panel and it was gone! I think it might be that it's all the same problem - the cabinet not having enough bracing.

Another fun fact: the noise is not there at 20hz! Maybe my box is resonating at 30hz? Or maybe the sub isn't as loud at 20hz... Well, the noise is also present at 38hz. Meh, I don't know what it is. Help me understand this, it's beyond my knowledge...

 

[lovinthehd]

Ok if you don't care about the sub level for using the avr without Dirac then yes that should be fine. I was thinking Dirac only 2ch with your setup and the avr being also able to be used in multi-ch mode but maybe you don't use it that way....

 

[yonyz]

Dirac's trial is running the multi-channel version, it controls all 6 channels of my setup. With its amp and huge cabinet I built, this sub should theoretically be able to reach a maximum of 110SPL at 30hz, and 108dB at 20hz. But I get the cabinet noise at a volume far below reference (85dB). My point being, it's not the volume. I mean, it is the volume, but it's the cabinet that's weak, not the driver being overdriven.

 

[lovinthehd]

I didn't realize Dirac had a multi-ch version for use on a pc, will have to go check that out. Theory/modeling and builds don't always jive Good luck at rebracing your cabinet, missed the part where you're getting the cabinet noises low (but fwiw sub should be 10dB higher than the other channels so "reference" would be 95 dB with 20dB peaks).

I recently built a 1262W sub for my bedroom but went sealed myself. Impressive for for the cost, hopefully even more so when I get the matching one built.

 

[yonyz]

Thank you for the help. I will update once I've installed additional bracing.

 

[yonyz]

Weekend is coming, and I got the pieces.

 

[yonyz]

I've installed the additional bracing. Have only watched a trailer and some test tones that are both known to produce the box noise, and it seems to be gone so, thank you. Mission accomplished, I think.

Edit: Did some more testing at decent volumes, it's fixed.
Thanks again.