Looking for driver and general sub advice - Page 2 - Home Theater Forum and Systems - HomeTheaterShack.com

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post #11 of 29 Old 12-12-09, 03:42 PM Thread Starter
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Re: Looking for driver and general sub advice

Probably the 300.
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post #12 of 29 Old 12-12-09, 04:04 PM
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Re: Looking for driver and general sub advice

2' wide x 2' tall x 3'deep is about 9 cu.ft. net volume. Tuned to 18 hz with a pair of 4" round ports 20" long each, the bash 300 would be a good match. I would mount the sub and ports on the front baffle.




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post #13 of 29 Old 12-12-09, 06:10 PM
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Re: Looking for driver and general sub advice

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I forgot to mention that I will generally be using low gain due to the wife (I forget the acronym y'all use). Also, I would like to tune it to 18 Hz or lower.
Just go with a 2'x2'x3' enclosure with a 29" 6" OD port. This will put you around the 14.9Hz area, and you can probably skip the HP.

The port can be on the same surface as the driver. You will want to keep the rear of the port at least it's ID from any other surfaces. I would put the port up top, and the driver on the open side though.

I have a sub (two actually) with that driver at 315l, tuned to 13.8Hz down-firing with no HP (signal is flat until the 3Hz filters kick in.), and it(they) have been running fine (and hard) for over 3 years.
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post #14 of 29 Old 12-18-09, 03:38 PM Thread Starter
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Re: Looking for driver and general sub advice

I think I will go with the driver and ports both on the front, so it will function better as an end table. After starting to lay it out, I quickly saw why Mike said 4" ports. There isn't room for a 6". Well maybe there is room, but it would be close to two sides. I've read in this forum that the back end of the port should be at least its diameter away from anything inside the box. The 4" ports come closer to achieving that, and the layout is symmetrical around the vertical centerline of the front, which is more pleasing to me. However, even with 4" ports I can't achieve that, particularly with radiusing the port ends and a driver grill that is larger than the driver. Will it be okay to angle the ports such that the inside end is closer to the center of the box than the front end? It would be an inch or two over a 20" length.
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post #15 of 29 Old 12-18-09, 03:56 PM
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Re: Looking for driver and general sub advice

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I think I will go with the driver and ports both on the front, so it will function better as an end table. After starting to lay it out, I quickly saw why Mike said 4" ports. There isn't room for a 6". Well maybe there is room, but it would be close to two sides. I've read in this forum that the back end of the port should be at least its diameter away from anything inside the box. The 4" ports come closer to achieving that, and the layout is symmetrical around the vertical centerline of the front, which is more pleasing to me. However, even with 4" ports I can't achieve that, particularly with radiusing the port ends and a driver grill that is larger than the driver. Will it be okay to angle the ports such that the inside end is closer to the center of the box than the front end? It would be an inch or two over a 20" length.
It would probably still be better to use the 6" port even with the limited distance. Remember you are going to be putting the port into the baffle so you would lose 3/4 to 1 1/2" on that alone.

You could easily make an angle. Just cut an angle at the distance you want to turn it at.

Then you can flip the pipe around and seal it up really good to create a joint. It's not perfect, but if your velocity is low enough it should work. If you have a miter saw. Use that to make the cut.
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post #16 of 29 Old 12-18-09, 04:42 PM
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Re: Looking for driver and general sub advice

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Dayton DVC385-88 15" DVC Series Subwoofer $150
This is one of two Dayton drivers that works with the Bill Fitzmaurice Tuba HT. That design would be something to strongly consider if you don't mind a good folded horn design. There are lots of people going nuts over that design right now around the net, and for good reason.
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post #17 of 29 Old 12-23-09, 03:14 PM Thread Starter
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Re: Looking for driver and general sub advice

Thanks again for all the advice, guys! I've been all over the place with design ideas so far. I mentioned before that I have space behind my theater seating adjacent to where the sub box will be. I would like to take advantage of the space for an external port or just box space to get larger volume if it is worthwhile. The space is about 7" x 12" x 8'. Worthwhile?

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post #18 of 29 Old 12-24-09, 11:45 AM Thread Starter
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Re: Looking for driver and general sub advice

I've been obsessing on this project for weeks now, thinking of different ways to make a larger enclosure fit in the space I have. I saw someone's wine barrel project, and it gave me the idea to disguise the box as a steamer trunk, or get an antique trunk and modify it. My wife nixed that idea, but thought a trunk would be good to disguise a dog crate. I am pretty settled on doing an end table design now. I will build a box, and then build a table to sit around it. I'll paint the box flat black, or cover with fabric. The driver and round 6" port will be on the front, and I'm thinking of hanging some black fabric loosely in front of that. I would think that will impede the sound less, especially from the port. Any thoughts on that, or fabric recommendations? I was trying to figure out ways to maximize the box volume (angle the sides, so it is larger in back; use the adjacent space behind the seats...). My 12 year old son saw me playing with REW, and asked what I was doing, and I explained it to him, and explained and showed him on REW what a difference a very large box makes. He said, "Why not just use an equalizer"? Why not indeed? I did a little modeling, and saw that it should be easy to match the curve of a 11ft^3 box with 8ft^3. Of course, I will lose a little SPL overall, but I don't think that is a problem. A hundred bucks for a BFD sounds like a bargain, rather than building a convoluted box shape. Right?

I was also wondering about bending 6" PVC pipe, so that the internal port end is at least 6" from the box sides. I found a thread about bending 4" by heating it with a torch. I suppose that would work for 6" too, especially since I don't need much of a bend. I'm figuring that a nice gentle bend is going to be better than a sharp one.
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post #19 of 29 Old 12-24-09, 12:33 PM
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Re: Looking for driver and general sub advice

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I did a little modeling, and saw that it should be easy to match the curve of a 11ft^3 box with 8ft^3
As long as:

1. The amp can supply the necessary power at the boost frequency. A 3 d boost requires twice the amplifier power.

2. The driver has the necessary Xmax to deal with the extra excursion there will be at the boost frequency.




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post #20 of 29 Old 12-24-09, 02:47 PM
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Re: Looking for driver and general sub advice

EQ is best left to a last resort thing IMO - if there's any possible way to get the box up to the size it needs to be, I'd do that first. As mentioned, you can run short on amp or excursion fast if you end up having to apply too much boost.
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