tower dimensions

Well,
I actually decided to go with the Modula MTM in a tower version instead of the Eros to save some money in case I wanted to build the center channel later. It uses 2 Dayton RS180's and the Seas 27TDFC Tweeter. As far as the box size...I've read that it should have a 50 liter internal volume with a down firing port. Could I get away with this box size?
9" x 12" x 45"? It will have a 1 1/2" thick front baffle and a couple 3/4" braces.
Also, I couldn't find this answer on Htguide either...
If I have a 3" down firing port- do I need 3" of clearance from the floor? Thanks again.

Quote:

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Originally Posted by hmmmm

Well,
I actually decided to go with the Modula MTM in a tower version instead of the Eros to save some money in case I wanted to build the center channel later. It uses 2 Dayton RS180's and the Seas 27TDFC Tweeter. As far as the box size...I've read that it should have a 50 liter internal volume with a down firing port. Could I get away with this box size?
9" x 12" x 45"? It will have a 1 1/2" thick front baffle and a couple 3/4" braces.
Also, I couldn't find this answer on Htguide either...
If I have a 3" down firing port- do I need 3" of clearance from the floor? Thanks again.

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If the internal volume is preserved and the front baffle width isn't altered you shouldn't have much issue...as for the downfiring port, I don't see why that is a must.

Check out Dr K's MTM's on the PE website, he allows for a 49 L box with a rear port if memory serves (though I'm told the Modula MTM is a slightly better crossover for a bit more money).
FYI - Roman Bednarek's sight has a good write-up on several versions of an MTM with those drivers....
http://rjbaudio.com/RS180MTM/rs180-rs28-mtm.html

Worth a read before you order xo parts (if you havent already).

Quote:

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Originally Posted by hmmmm

Well,
I actually decided to go with the Modula MTM in a tower version .... It uses 2 Dayton RS180's and the Seas 27TDFC Tweeter. As far as the box size...I've read that it should have a 50 liter internal volume with a down firing port. Could I get away with this box size?
9" x 12" x 45"? It will have a 1 1/2" thick front baffle and a couple 3/4" braces.
Also, I couldn't find this answer on Htguide either...
If I have a 3" down firing port- do I need 3" of clearance from the floor? Thanks again.

---

My BassBox Pro program recommends a 35 litre box for a pair of RS180's when using light damping, (smaller size with more damping). That box would use 3 x 7.75 vent. I don't see why you would want bottom venting.

35 litres would yield a yield a box of external dimesions about 9 x 12 x 31 inches -- short for a tower.

But I defer to an expert like Kex, not to mention RJB or Jon Marsh.

Quote:

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Originally Posted by Feanor

My BassBox Pro program recommends a 35 litre box for a pair of RS180's when using light damping, (smaller size with more damping). That box would use 3 x 7.75 vent. .

35 litres would yield a yield a box of external dimesions about 9 x 12 x 31 inches -- short for a tower.
.

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Well, I'm just going by what they are recommending at HTguide.com for internal volume for a tower. -I guess it helps with a lower bass extension.

"I don't see why you would want bottom venting"

I don't want to take quotes from that site, but they say it does make it easier to install a longer port in a narrow cabinent and also has certain advantages (which is above my understanding). Unfortunately, this makes it even taller.

Quote:

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Originally Posted by kexodusc

Check out Dr K's MTM's on the PE website, he allows for a 49 L box with a rear port if memory serves (though I'm told the Modula MTM is a slightly better crossover for a bit more money).
FYI - Roman Bednarek's sight has a good write-up on several versions of an MTM with those drivers....
http://rjbaudio.com/RS180MTM/rs180-rs28-mtm.html

Worth a read before you order xo parts (if you havent already).

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Thanks Kex,
I'll read those write-ups before I order anything. I've also read the Modula's crossover is better- it's still cheaper than building the Eros! I figured I might want the center channel etc... in the future so I'll save the money and do the Modula.

Quote:

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Originally Posted by hmmmm

Well, I'm just going by what they are recommending at HTguide.com for internal volume for a tower. -I guess it helps with a lower bass extension.

"I don't see why you would want bottom venting"

I don't want to take quotes from that site, but they say it does make it easier to install a longer port in a narrow cabinent and also has certain advantages (which is above my understanding). Unfortunately, this makes it even taller.

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I had a quick look at HTguide but didn't spot the tower volume reference -- not matter. But I did see that Jon Marsh's original MTM was build in a 1 ft^3 Parts Express cabinet.

Well, I guess you could put a relatively vent on the top of shallow cabinet. Might want to cover it with a grill of some kind, though. :biggrin5:

Quote:

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Originally Posted by Feanor

But I defer to an expert like Kex, not to mention RJB or Jon Marsh.

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Good, I defer to RJB and Jon Marsh daily...those guys know more about crossover design than I know about myself!!! I can't even spell cauer eliptic let alone desing one :D

Quote:

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Originally Posted by Feanor

I had a quick look at HTguide but didn't spot the tower volume reference -- not matter. But I did see that Jon Marsh's original MTM was build in a 1 ft^3 Parts Express cabinet.

Well, I guess you could put a relatively vent on the top of shallow cabinet. Might want to cover it with a grill of some kind, though. :biggrin5:

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The bottom venting would be minimally easier to install I suppose, but a decent elbow like you'd use for plumbing, provided the internal volume/length is the same would allow for rear or front venting...don't worry about getting the port length exact...try modelling a few different lengths give or take an inch and it won't make 1 lick of audible difference. There'll be more variance in the Fs of the drivers than the tuning frequency from a bit of port length caused by an elbow....I'd just take a string, measure the inside and outside lenghts of the elbowed vent and use the average as an approximate if you really want to get precise...there's probably a better math formula somewhere though.

I'd worry about bottom venting if they were only a few inches from the floor...ideally you'll want 4 to 6 inches of clearance for any port to limit noise!