[karlsaudio]

Doing more thinking about the idea, I am thinking of building a coffe table sized sub. The size would be 17" H, 22" W and 44" L. With that kind of volume, what size and/or how many drivers would I use? This will be sealed.


Thanks

 

[karlsaudio]

Oh, I would like the FR be flat down to 15-18 Hz. What wattage requirements as well. It will be in a 12 X 18 room. Not looking to blow the windows out. Just nice, mid SPLs.

 

[reecew]

How much money do you have to spend?

 

[jpmst3]

The main problem with a coffee table sub is placement.


Placing a sub in the center of the listening area is often the worst possible place. It work decent for and MBM style setup.


I would try a sub in that location before I start cutting wood.


The other problem can be getting wires to it, but that is probably much easier than overcoming placement.

 

[karlsaudio]

Is a sub placed in the middle of a room that bad? I do have a sub now and can play with it's placement but, it is not in the room I will be setting all this stuff up in. I was just thinking it would be nice to have one as a functional table as well. Maybe not such a good idea??? As far as the money is concerned, I am thinking $4-500 for the parts.

 

[jpmst3]

Yes, generally it is THAT bad.


Here are some guidelines , note the first bullet in the list.

 

[jpmst3]

I mean it will work, but you may not get much out of it at your listening position.

What about endtables if that is an option?


I went that route and am very happy with the results...

 

[karlsaudio]

End tables would work. Two smaller ones. Then I wouldn't be stuck with the one big one. With the same $4-500 budget, what are my options?

 

[karlsaudio]



Quote:
Originally Posted by jpmst3 /forum/post/18235366


Yes, generally it is THAT bad.


Here are some guidelines , note the first bullet in the list.

Everything was going great down the line of points until the last one about concrete walls and floors. I have a tile floor and wood panel walls. How doomed am I? I am not going to futz with the walls other than some accoustic panels.

 

[jpmst3]



Quote:
Originally Posted by karlsaudio /forum/post/18236713


Everything was going great down the line of points until the last one about concrete walls and floors. I have a tile floor and wood panel walls. How doomed am I? I am not going to futz with the walls other than some accoustic panels.

Well, you can only control what you can control and have to live with what you have.

Of course, it is less than ideal, but it is what it is. Furnishings, carpeting, etc. help with absorption and if you have to you can add some bass traps if it is really bad. Wood paneling with absorb some as well.

But, I would not get bent out of shape about it and go for it. I mean no matter what it will be better than nothing, right?


Here is a link to my thread .

 

[karlsaudio]

Great thread jpmst3! 80 lb drivers! Holy Sh$* Also shows how much I might have to spend. Ouch!

(are you a MST3K fan??)

 

[jpmst3]



Quote:
Originally Posted by karlsaudio /forum/post/18238020


Great thread jpmst3! 80 lb drivers! Holy Sh$* Also shows how much I might have to spend. Ouch!

(are you a MST3K fan??)

Thanks!


I guess not, I don't know what a MST3K is?

 

[A9X-308]



Quote:
Originally Posted by jpmst3 /forum/post/18235366


Yes, generally it is THAT bad.


Here are some guidelines , note the first bullet in the list.

Rubbish. With a sub away from walls, you get less boundary reinforcement, but positioning is still beholden to the nulls of the modes for a given room. If you were to place it right in the centre of a room you would not excite either the first length or width mode, but you would get some reinforcement depending upon dimensions and construction. However LF reinforcement through boundaries may not be all the much, and may even be absorptive depending upon the construction of the room. U/G basement concrete bunker will get lots, 2nd floor timber and plasterboard will get much less. It's also dependent upon room size and the frequency in question.


Also having the sub in a coffee table will give you some gain, simply because there is less attenuation with distance as it's closer (assuming in front of the listening couch. A couch end table sub may not be all that different from a coffee table one as they will only be sightly different wrt boundaries in a large room.


Two smaller subs will give more flexibility in positioning and can help with averaging modes out across the LPs as per Toole etc.


KA, a couple of Shivas/Tempests in two separate enclosures that fit with your dimensional needs, sealed would be within your budget.

 

[jpmst3]



Quote:
Originally Posted by A9X-308 /forum/post/18239078


Rubbish. With a sub away from walls, you get less boundary reinforcement, but positioning is still beholden to the nulls of the modes for a given room. If you were to place it right in the centre of a room you would not excite either the first length or width mode, but you would get some reinforcement depending upon dimensions and construction. However LF reinforcement through boundaries may not be all the much, and may even be absorptive depending upon the construction of the room. U/G basement concrete bunker will get lots, 2nd floor timber and plasterboard will get much less. It's also dependent upon room size and the frequency in question.

I dunno. I tried it in my room and it was terrible.

Of course, like most things HT, results vary.


I suggested he try it first with an existing and see what the response looks like before cutting wood...

 

[mayhem13]

I guess it really depends on the goals. The centered coffee table as pointed out will entice less response from the room....which overall might be smoother but the boundry loaded unit louder.....pick your poison. I'd go with the two end tables on either side of the listening position for a few reasons.....smoother in room response, ergonomically easier, and available boundry gain if needed or wanted. $500 gets the job done either way. Might i suggest two boxes each loaded with a Dayton RSS315-8 and the Oaudio 500w plate amp. One unit active and the second a parallel slave. About 2cuft net for each. With the available room gain and eQ of the amp 18-20hz in room response is likely.

 

[karlsaudio]



Quote:
Originally Posted by jpmst3 /forum/post/18238060


Thanks!


I guess not, I don't know what a MST3K is?

Sorry, the "mst3" made me ask. MST3K stands for Mystery Science Theater 3000. Was a goofy show from the late 80s that went on to become a movie.

 

[karlsaudio]



Quote:
Originally Posted by mayhem13 /forum/post/18239170


I guess it really depends on the goals. The centered coffee table as pointed out will entice less response from the room....which overall might be smoother but the boundry loaded unit louder.....pick your poison. I'd go with the two end tables on either side of the listening position for a few reasons.....smoother in room response, ergonomically easier, and available boundry gain if needed or wanted. $500 gets the job done either way. Might i suggest two boxes each loaded with a Dayton RSS315-8 and the Oaudio 500w plate amp. One unit active and the second a parallel slave. About 2cuft net for each. With the available room gain and eQ of the amp 18-20hz in room response is likely.

Where does one find these parts?

 

[A9X-308]



Quote:
Originally Posted by mayhem13 /forum/post/18239170


I guess it really depends on the goals. The centered coffee table as pointed out will entice less response from the room....which overall might be smoother but the boundry loaded unit louder.....pick your poison.

For sure, but it should be tried first rather than one format simply being dismissed out of hand. As you mentioned, with an existing sub present it is very easy to try out.

 

[jpmst3]



Quote:
Originally Posted by karlsaudio /forum/post/18239205


Sorry, the "mst3" made me ask. MST3K stands for Mystery Science Theater 3000. Was a goofy show from the late 80s that went on to become a movie.

Oh, that explains that.


Ya, I actually did watch that on occasion back in the '80's.

I didn't even realize they made a movie from it.

 

[mayhem13]



Quote:
Originally Posted by karlsaudio /forum/post/18239215


Where does one find these parts?

Partsexpress.com

Oaudio.com


As others have mentioned and you do have a portable sub, get it into the room and move it around a bit.....see how it works out first.