sub help

[dino]

hello all . I have a chance to buy a used a cab that use to hold 1-jbl 2245h -1 2202h and 1 -2370 horn. I was thinking maybe I could cover up the 2202 and the 2370 area with a 1 inch plywood the cab size is 32/24/42 is this to much or will it work. the guy want 89 each cab. thanks

[dino]

hello all . I have a chance to buy a used a cab that use to hold 1-jbl 2245h -1 2202h and 1 -2370 horn. I was thinking maybe I could cover up the 2202 and the 2370 area with a 1 inch plywood the cab size is 32/24/42 is this to much or will it work. the guy want 89 each cab. thanks
the cab is already tuned to what I dont know of yet I am waiting on his answer. It is a hell of alot cheaper for me to buy and do it this way if it is possible

[Mr. Widget]

If the cabs are solid and well braced you can't go wrong. I just bought the material to build a pair of much smaller subs for a pair of Sub1500s using the same techniques shown here: http://www.audioheritage.org/vbulletin/showthread.php?t=9812

Admittedly this technique uses a lot of wood, but I paid $250 for the material alone.


Widget

[Loren42]

hello all . I have a chance to buy a used a cab that use to hold 1-jbl 2245h -1 2202h and 1 -2370 horn. I was thinking maybe I could cover up the 2202 and the 2370 area with a 1 inch plywood the cab size is 32/24/42 is this to much or will it work. the guy want 89 each cab. thanks

I don't know how the cabinet is made, but if the 2202 and the 2245 share the same internal volume you will change the cabinet resonance tuning by doing what you recommend in two ways:

1) The displacement volume of the 2202 will be removed from the cabinet and essentially increase the total internal volume by that amount.

2) The 2202 and 2245 were designed to share the volume in the cabinet and ports, so there will be some loss of the coordinated intended volume and probably the tuning of the ports.

Neither problem is difficult to overcome, you just need to reduce the internal volume by adding panels or some object internally (bags of play sand) to retune the cabinet volume. You may also need to adjust the ports, but I would start by sweeping a signal into the cabinet and looking for the resonance point with the driver you intend to put in mounted in the cabinet and the unused drivers' openings plugged.

I don't know how much of an impact not compensating will really make, but from an academic point of view it is a real argument. If you can do an impedance test before the original drivers are removed you will have a baseline for the original resonance point, but it sounds like that may not be possible.

If the 2202 and 2245 do not share the same volume, then it does not make a difference.

[dino]

I don't know how the cabinet is made, but if the 2202 and the 2245 share the same internal volume you will change the cabinet resonance tuning by doing what you recommend in two ways:

1) The displacement volume of the 2202 will be removed from the cabinet and essentially increase the total internal volume by that amount.

2) The 2202 and 2245 were designed to share the volume in the cabinet and ports, so there will be some loss of the coordinated intended volume and probably the tuning of the ports.

Neither problem is difficult to overcome, you just need to reduce the internal volume by adding panels or some object internally (bags of play sand) to retune the cabinet volume. You may also need to adjust the ports, but I would start by sweeping a signal into the cabinet and looking for the resonance point with the driver you intend to put in mounted in the cabinet and the unused drivers' openings plugged.

I don't know how much of an impact not compensating will really make, but from an academic point of view it is a real argument. If you can do an impedance test before the original drivers are removed you will have a baseline for the original resonance point, but it sounds like that may not be possible.

If the 2202 and 2245 do not share the same volume, then it does not make a difference. well for what I see for now it look like there is no dog house for the 2202 the inside cab looks to be completely open from the inside. I wont know for sure until I receive an answer from this guy. if there is a dog house or not I should be able to add or subtract from the inside measurements of the cab and get my cubic ft volume. than find out what my tunning should be and what size ports should I use and a simple passive xover or am I missing something

[Mr. Widget]

I should be able to add or subtract from the inside measurements of the cab and get my cubic ft volume. than find out what my tunning should be and what size ports should I use and a simple passive xover or am I missing somethingAbsolutely... you have it. The only issue I could see would be whether or not the cabs were well made to begin with. Even some of our beloved JBLs could use some serious work to make them as good as they can be.

Things to look for are: (1) Cabinet material and thickness. (2) Amount and type of bracing. (3) Type of joints and the quality of construction.

The actual volume is easily adjusted and the tuning frequency can be easily adjusted as well.


Widget

[Loren42]

well for what I see for now it look like there is no dog house for the 2202 the inside cab looks to be completely open from the inside. I wont know for sure until I receive an answer from this guy. if there is a dog house or not I should be able to add or subtract from the inside measurements of the cab and get my cubic ft volume. than find out what my tunning should be and what size ports should I use and a simple passive xover or am I missing something

Pretty much. Finding what the tuning should be is a little subjective, but the port diameter is fine. You may need to alter the length. Longer ports will drop the resonance frequency and shorter raises that resonance.

The crossover is another matter and depends where you want to crossover to the other speakers you are using. The crossover point is really something you have to determine based on your total system and maybe your room, too.

If you can use an active crossover for this, so much the better. Ideally, it would be good to have a separate stereo amp to drive the two cabinets and some form of an active crossover. The nice thing with a 2-way active crossover is that you can adjust the crossover point and the type of slope by simply turning knobs. However, with infinite flexibility comes additional work to dial it in, but its no different than designing a passive crossover. You still have to decide where you want to crossover and at what slope.

The exception is if you get the passive crossover wrong you have to open the cabinets and change out components. With an active crossover you have to reach up and turn a knob.

[dino]

Absolutely... you have it. The only issue I could see would be whether or not the cabs were well made to begin with. Even some of our beloved JBLs could use some serious work to make them as good as they can be.

Things to look for are: (1) Cabinet material and thickness. (2) Amount and type of bracing. (3) Type of joints and the quality of construction.

The actual volume is easily adjusted and the tuning frequency can be easily adjusted as well.


WidgetI will ad pic as soon as i receive the cab thank u sir and loren42 for the both of your input :applaud: