[quadriverfalls]

I'm on a mission (or at least exploring the possibility) of building some on-wall or in-wall speakers for a secondary HT which will be used nearly 100% for HT or TV viewing. I'm not real sure that I will be placing a sub in the room (or if I do, it will be a fairly small one) so I started my research using 8" midbass drivers as a start point to (hopefully) get as much extension as possible. When I plugged the TSP's of the driver into WinISD, I got a Vb of: 131.28. Does that mean 131.28 "cubic liters?"

Correct me if I'm wrong, but that enclosure would need to be HUGE!


Here are the numbers from the driver if someone wants to run them....

VAS 51 Lt
Qts 0.6
Fs 31 Hz

Using a Otc of 0.7


Thanks in advance for your time.

 

[Fatawan]

131 liters is 4.6 cubic feet--not huge

 

[mayhem13]



Quote:
Originally Posted by Fatawan /forum/post/16869542


131 liters is 4.6 cubic feet--not huge

It is for on wall speakers!

Hanging those wouldn't be fun.

 

[LTD02]

why would a "cubic liter" be any larger than a non-cubic liter? ;-)

 

[quadriverfalls]



Quote:
Originally Posted by mayhem13 /forum/post/16869651


It is for on wall speakers!

Hanging those wouldn't be fun.

Well, I was originally "thinking" on-wall, but in-wall would certainly be a possibility if I had to use such a large enclosure. This particular midbass driver is kind of expensive, but it is designed for sealed enclosures. Maybe I just need to look for another driver and take whatever I get with regard to extension.


Like I said, this isn't for critical listening, but I'd still like it to sound nice for when we did use it. Especially since it's my main HT right now as I go through a total re-hab in my lower level and main HT due to some unwanted flooding issues.

 

[quadriverfalls]



Quote:
Originally Posted by LTD02 /forum/post/16869692


why would a "cubic liter" be any larger than a non-cubic liter? ;-)

Well, I DID say that I was confused.

Which for those of you that know me well, that's not unusual.

 

[A9X-308]



Quote:
Originally Posted by quadriverfalls /forum/post/16869526


I'm on a mission (or at least exploring the possibility) of building some on-wall or in-wall speakers for a secondary HT which will be used nearly 100% for HT or TV viewing. I'm not real sure that I will be placing a sub in the room (or if I do, it will be a fairly small one) so I started my research using 8" midbass drivers as a start point to (hopefully) get as much extension as possible. When I plugged the TSP's of the driver into WinISD, I got a Vb of: 131.28. Does that mean 131.28 "cubic liters?"

Correct me if I'm wrong, but that enclosure would need to be HUGE!


Here are the numbers from the driver if someone wants to run them....

VAS 51 Lt
Qts 0.6
Fs 31 Hz

Using a Otc of 0.7


Thanks in advance for your time.

I get 125L Vb and 36.5Hz Fs.


The reason the box needs to be so large is that an in wall speaker is assumed to have a large air cavity to work into, so the Qts is high. You are going to need to use a different driver if you want a small enclosure, but be prepared to meet Mr Hoffman* along the way.


* Hoffman's Iron Law . The first couple of paragraphs explain it.

 

[mosconiac]

That's a ridiculously large volume for a 8" midbass. Are you sure it isn't intended to be used as a sub? ...not much extension for midbass duties...

 

[quadriverfalls]



Quote:
Originally Posted by mosconiac /forum/post/16869862


That's a ridiculously large volume for a 8" midbass. Are you sure it isn't intended to be used as a sub? ...not much extension for midbass duties...

Well, I suppose it COULD be designed for sub woofage duty. But it's listed on the 8" "woofer" page on Madisound's site not on the subwoofer page. Here is the PDF: http://www.madisound.com/catalog/PDF/CAW938.pdf


And on the main page, it DOES say that they recommend a 2.0 cu. ft. SEALED box and they don't recommend a vented enclosure. http://www.madisound.com/catalog/pro...oducts_id=8440


Now, you can see my confusion. I'm thinking that 2.0 cu. ft. isn't so bad at all and then I plug the numbers into Win ISD and got something totally different.

 

[cc00541]

The Morel is a bit of an unusual compromise in a driver. It plays quite low sealed, but can't play very loud without exceeding Xmax. The smaller enclosure suggested by Mad provides a higher Qt of around .9, which helps hold down the driver excursion a bit, but its still not going to play very loudly. Like 96dB max SPL not very loudly...

FWIW: -I also noted that Morels T/S parameters don't add up'. I used the published values for Qe, Qm and obtained significantly different values for Bl, Vas, Cms, etc.


For an 8 driver alternative, you might consider the Peerless 830884. -Vented in the same 2ft^3 enclosure and tuned to 31Hz, it provides the same f3 and f10 as the Morel, but the max SPL is closer to 105 dB.


C

 

[quadriverfalls]



Quote:
Originally Posted by cc00541 /forum/post/16870420


The Morel is a bit of an unusual compromise in a driver. It plays quite low sealed, but can't play very loud without exceeding Xmax. The smaller enclosure suggested by Mad provides a higher Qt of around .9, which helps hold down the driver excursion a bit, but its still not going to play very loudly. Like 96dB max SPL not very loudly...

FWIW: -I also noted that Morels T/S parameters don't add up'. I used the published values for Qe, Qm and obtained significantly different values for Bl, Vas, Cms, etc.


For an 8 driver alternative, you might consider the Peerless 830884. -Vented in the same 2ft^3 enclosure and tuned to 31Hz, it provides the same f3 and f10 as the Morel, but the max SPL is closer to 105 dB.


C

But I'm not real sure there's going to be a very good way to "vent" an enclosure that's not more than 3-1/2" deep. Again, I'm pretty new at all of this so please bare with me folks.

I haven't checked the Peerless driver yet, but the Morel was a little above my intended budget for three midbass drivers. I'm just doing the front three channels (since the surrounds will need to be ceiling mounted in this room so I'll go with something off the shelf for those) I don't mind a little extra $$$ for the drivers.


Thanks again for all of the help everyone.

 

[LTD02]



Quote:
Originally Posted by quadriverfalls /forum/post/16870957


But I'm not real sure there's going to be a very good way to "vent" an enclosure that's not more than 3-1/2" deep. Again, I'm pretty new at all of this so please bare with me folks.

hey, you are doing great.


the more serious problem is that you mention a driver, but not the rest of the system. how are you going to build crossovers? is this a two-way, or three-way system?

 

[quadriverfalls]



Quote:
Originally Posted by LTD02 /forum/post/16871161


hey, you are doing great.


the more serious problem is that you mention a driver, but not the rest of the system. how are you going to build crossovers? is this a two-way, or three-way system?

Thanks.... I don't feel all that "great."

So many numbers that mean something it's almost all a blur at this point. What makes things even worse is they can all change with just one itty-bitty thing out of whack.

Very simple two way crossover. I haven't really looked all that much at tweeters yet. I would really like to get my midbass driver lined up first and then worry about finding a tweeter that will integrate and match up well with the midbass driver.

 

[LTD02]



Quote:
Originally Posted by quadriverfalls /forum/post/16873011



Very simple two way crossover. I haven't really looked all that much at tweeters yet. I would really like to get my midbass driver lined up first and then worry about finding a tweeter that will integrate and match up well with the midbass driver.

a good two-way crossover is no "simple" thing.


just a heads-up...unless you are going active, you are venturing into an area that folks spend many years to learn.


maybe you should take a look at the monster thread at audiokarma.org on the "econowave".


it is a two-way, horn-loaded, design where you can choose your woofer. crossovers already designed.


are such flexible designs perfect, no. however, it may be exactly for which you are looking.

 

[cc00541]



Quote:
Originally Posted by quadriverfalls /forum/post/16873011


Thanks.... I don't feel all that "great."

Don't worry. We were all there once, and can certainly emphasize with you.


LTDO2's suggestion is a good one. I feel the best way to get your feet wet is to build an already proven design. Most designs will have a significant amount of baffle step compensation factored in and would not be suitable for your application. However there should be a few appropriate DIY designs out there.


C

 

[quadriverfalls]



Quote:
Originally Posted by cc00541 /forum/post/16874435


Don't worry. We were all there once, and can certainly emphasize with you.


LTDO2's suggestion is a good one. I feel the best way to get your feet wet is to build an already proven design. Most designs will have a significant amount of baffle step compensation factored in and would not be suitable for your application. However there should be a few appropriate DIY designs out there.


C

Thanks.... but the more I dive into this, the more frustrated I'm becoming. Maybe I should just forget about it and buy something off the shelf. Still though, I'm kind of spoiled when it comes to in-walls. I've heard some of the best (TRIAD Bronze) and RBH (I don't remember the model) and of course, a lot of the crapola.


Since something like the TRIAD and RBH are way out of bounds with regard to the budget, I thought I might try DIY and get at least some of the way there at a more reasonable cost.


Sigh....

 

[cc00541]

What's your budget per speaker?


C

 

[quadriverfalls]



Quote:
Originally Posted by cc00541 /forum/post/16876023


What's your budget per speaker?


C

LOL.... well, that's a loaded question. I had "envisioned" around ~$150 per speaker before I started. Now, it's hovering around ~$250. Even though I'm only doing the front soundstage, that's pretty much the limit as to where I'd feel comfortable I think. Obviously, if I could come up with something nice for less, I'm all for that.


I need to maybe "re-think" my position of putting much in the way of a sub in the room. I just don't think I'm going to get much extension in any type of sealed enclosure using a seven or eight inch driver. I had hoped to use a small sub I've got to just "fill in" the bottom end a bit. I'm not looking for chest thumping bass or anything close out of the sub, just some extension and presence. I've never crossed it higher than 80 Hz before so I have no idea how capable it is above that. Obviously, if I take it up to 100 Hz and it integrates well.... hooray. Things would be nice. But I'm thinking that would tax the little beastie more than it's able to handle. So I was shooting to get some extension down to 80 Hz out of the mains and then let the sub take over from there and give me whatever he's got in the way of some extension down below 80 Hz adding some bass "presence" without worrying about any major SPL's.


I suppose I could just mount drivers on a baffle and use the wall cavity, but I don't think that's a very good option. At least not without opening up the entire wall cavity room side and meticulously sealing the back side of the wall cavity first.

 

[quadriverfalls]

I should also add that the wall cavity in question is insulated which will reduce volume of the enclosure significantly correct (or do I have that assbackwards)? I suppose I could live without the insulation since the backside is protected from the weather somewhat by an un-heated garage. Even using the entire wall cavity, 14.5" x 93" x 3.5" = 4719.75 / 1728 = 2.73134 Cu. Ft. Which would STILL only be 77.343 liters. Well short of what WinISD recommends or even the 125 liters that A9X-308 came up with. So I think that driver is out now period.