thunda1216 said:
You are both right. Batt type insulation would make the cab seem effectively "bigger" I am wondering about rigid foam though. Like the hard foam. Either way I have a feeling it would impact the sound unpredictably.
Anyone try to "shrink" a rectifier cab?
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You are both right. Batt type insulation would make the cab seem effectively "bigger" I am wondering about rigid foam though. Like the hard foam. Either way I have a feeling it would impact the sound unpredictably.
Not every good idea is a good idea :roll: You do not need a bigger envelope. I may just try the foam in mine to see if it makes good sense or bad. I like to tinker with things so why not, this has sparked my curiosity.
Also I had a thought, And I could be totally wrong on this. But, I would probably wrap the inner sides with it and not put anything on the back cover. I have a feeling that the resonance of the back adds to the "woody" character of the cab. Where as the sides don't seem to flex or vibrate as much due to them being smaller and very rigid. Again this is just a guess.
That is what I was considering. just placing the foam on top, bottom and sides and leave the back and baffle alone. If I do it, I will make note if it is worth the effort or not.
Crap, the more I think it over, the more I want to experiment with it. The only issue, securing the material in place so it does not move around during use. and if it does not work out, trying to remove it would be a mess if secured with glue (assuming it would stick, liquid nails ?) If I do this, it will be without glue.
Some how I believe this will not work out as intended. :? If it really made sense to do so, it would have been done already.
Some how I believe this will not work out as intended. :? If it really made sense to do so, it would have been done already.
Blaklynx
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bandit2013 said:
You can always use patches of velcro to start with. So what if the cab has some velcro patches inside if you decide to remove the foam pads.
thunda1216
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bandit2013 said:
Duct Tape. Fixes anything.
Something is stirring in my mind indicates that it will not work. I am by no means and acoustic engineer. The foam may impair the resonant frequency of the cabinet. Worse if it causes the back panel to vibrate more. I would fathom the reason behind the 2x4 beam is to prevent oscillations of the back panel. Also, I have experience what happens if the 2x4 is not secure to the back panel, it will vibrate like a large tuning fork. After I opened up the cab the first time, I needed to secure the back panel with screws to the 2x4 otherwise it would vibrate and sound terrible.
If you have never opened up the 412 before, you need to remove one of the handles and use a hammer to break the seal. The same sealing strips are also used on the beam. Note, the beam is stapled and glued to the front of the cabinet. It will take a considerable effort to open the cabinet, also, if you do so, do not hit the magnets of the speaker (sudden shock can cause loss of magnetism, this is more prone to ALNICO drivers than Ceramic but still can happen) A rubber mallet would be best (non-magnetic type) as the speakers will grab hold of the hammer quite easily.
When it comes to speakers, if you decide to replace two or all four, double check if the speaker is suitable for use in a sealed enclosure and what the minimum or maximum volume of the speaker should be. Most speaker manufacturers may have this information listed on the specification literature. If the foam would actually make the cabinet appear to have more volume it may be self defeating to add it. Also, considering how much vibration I can feel on the outside of the cabinet when the speakers I being driven, if the insert to reduce the volume of the enclosure is not secured properly, it will eventually become a noise maker. I wonder if packing peanuts would be more effective. :lol: ignore that last comment.
If you have never opened up the 412 before, you need to remove one of the handles and use a hammer to break the seal. The same sealing strips are also used on the beam. Note, the beam is stapled and glued to the front of the cabinet. It will take a considerable effort to open the cabinet, also, if you do so, do not hit the magnets of the speaker (sudden shock can cause loss of magnetism, this is more prone to ALNICO drivers than Ceramic but still can happen) A rubber mallet would be best (non-magnetic type) as the speakers will grab hold of the hammer quite easily.
When it comes to speakers, if you decide to replace two or all four, double check if the speaker is suitable for use in a sealed enclosure and what the minimum or maximum volume of the speaker should be. Most speaker manufacturers may have this information listed on the specification literature. If the foam would actually make the cabinet appear to have more volume it may be self defeating to add it. Also, considering how much vibration I can feel on the outside of the cabinet when the speakers I being driven, if the insert to reduce the volume of the enclosure is not secured properly, it will eventually become a noise maker. I wonder if packing peanuts would be more effective. :lol: ignore that last comment.
I changed the response of my XXX cab by putting padding on the back, bottom, and one side. It was a subtle change, but did reduce resonance below about 150 Hz. It's on casters, so there is almost no absorption into the floor. By reducing the BOOM, it made the SMACK come out a little more.
After some thought I think I am going to try this but I am not going to use foam. I am going to use a 2x12 or 2x10, whatever I can fit in there, mounted along the bottom and possibly the top. I have calculated the difference in cab volume to be roughly .72 cubic feet. So, I'll just calculate how much wood I need to make that volume. I'll let you all know my results.
You could always vent the cab without any modifications. Just remove the handles on the sides. I have done this without any ill effects, actually made the cabinet sound louder.
I was looking into this subject matter on the web. Instead of trying to alter the size of the box with more wood, just placing something inside of the cab would work. I have read about use of sand bags. Not sure how that would work but may do what you want. Also you can remove them or change their shape to suit your needs. Just a thought, not sure if it has been mentioned before.
bandit2013 said:
Yes I have thought of this as well. I think I am going to try out lengths of 2x12 secured to the top and bottom of the cab. I may actually try out sand bags. It won't take much. I calculate a .71 cubic foot difference between the cab sizes roughly.
I also believe that the back surface of the cab would provide the most resonance and the sides, top, and bottom very little so whatever method I choose I will avoid adding mass to the back of the cab.
A) Often cabs are tuned for efficiency, so perhaps the cab is a particular size for a reason.
B) Ports are specifically designed with exact dimensions to work properly.
C) Inside insulation is usually installed to eliminate standing waves between parallel surfaces.
But hey, let's make that huge, heavy cab nice and manageable by loading it with sand bags.
At least in won't move around so much in the back of the Honda.
B) Ports are specifically designed with exact dimensions to work properly.
C) Inside insulation is usually installed to eliminate standing waves between parallel surfaces.
But hey, let's make that huge, heavy cab nice and manageable by loading it with sand bags.
At least in won't move around so much in the back of the Honda.
MrMarkIII said:
The dimensions of the oversized cab give it the big bottom (talk about bun cakes, my girl's got 'em). Being both deeper and wider give it larger corners to allow the slower moving frequencies to vibrate more freely.
To take out some of the bottom with little fuss or weight, a bass trap of some sort would probably do it. Although I don't think it would necessarily be the right option in a cab, think about the how some drummers put a pillow in their kick drum. Put a bass trap in one corner from the back panel to a bit short of the baffle. Perhaps some velcro would be useful to ballpark it before a more secure option is used. Short of doing calculus, it's going to be a hack science, but it probably won't be difficult. Cellulose, AFB, and mineral wool are some of the DIY options. Probably won't need much, since it's a cab and not a room.
On the other hand, if it's on casters have you tried putting it square on the floor? Floors love absorbing bass; carpet in particular.
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