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Discussion Starter · #41 ·
The boxes are made from 3/4" MDF. Each box consists of 4 16"x16" pieces and 2 16"x14.5" to make the final dimension 16"x16"x17.5". I didn't do any internal bracing but if I did it again I would attempt. At the time it just seemed like another hurdle for my first project, but I have plenty of leftover MDF that I could have added a brace to each and still had lots left for "oops" moments. I didn't use any damping in the boxes as they are already a little on the large side for these drivers.


If you haven't done so already you should download WinISD or Unibox and run some models. I did plug in the parameters for the 13Ov.2 and let it calculate the box size for a Qtc of .707 - according to Unibox it would be "ideal" in a 18L box (as compared to the 26L box it told me to put the 13Kv.2 in). The boxes I built ended up being more like 50L though which extends the F3 but can be dangerous for the drivers (at max power from the EP2500 I would be pushing them ~7mm past XMax at 10Hz).
 

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Did you stuff the boxes with anything?
 

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Quote:
Originally Posted by lennon_68 /forum/post/14219820


If you haven't done so already you should download WinISD or Unibox and run some models. I did plug in the parameters for the 13Ov.2 and let it calculate the box size for a Qtc of .707 - according to Unibox it would be "ideal" in a 18L box (as compared to the 26L box it told me to put the 13Kv.2 in).

Just curious if you param's match mine for what you entered in Ov2. Win ISD for a qtc .702 sealed spit out a 32L box.

 

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Discussion Starter · #45 ·

Quote:
Originally Posted by Kubbie /forum/post/14257394


Just curious if you param's match mine for what you entered in Ov2. Win ISD for a qtc .702 sealed spit out a 32L box.


Something isn't matching up... it's probably on my end though as I don't remember it telling me to put mine in 26L either, I was thinking it was more like 45L... I'm re-downloading Unibox now to retry, for some reason the excel spreadsheet got locked or something, I wasn't able to edit anything or recalculate anything (I think it has something to do with Vista...). I'll model it again and let you know what I find out.
 

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Discussion Starter · #46 ·
Well, I re-entered it and came up with the same numbers?? One thing I noticed, on your numbers it calculated the Qts=.399 but the actual Qts for the driver = .28 - when I enter the parameters in Unibox it calculated the Qts to .28 as well... Also the sensitivity on yours calculated to 86.07 dB but the sensitivity stated on the web page is 89.1 (which Unibox also calculated the same). I don't see anything wrong with the data entered though... Does anyone else see anything wrong? Maybe someone else could model it up and see what's going on.
 

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Looks great lemon, I may have to copy you if thats OK


Stupid question:

Any reason you went with 4 seperate boxes and not, say 2 boxes with 2 drivers each? Just seems like wasted effort unless you put them all over your room (to much hastle for me).

How much difference would there be with only two of your subs running?

Also, what BFD did you use? There seems to be two about $50 difference.


My mains can handle everything down to about 30Hz really well (Polk RTi12's with a Carver M1.5-t pushing them) and my Velodyne DPS-12 is OK for what it is, but I want to go quite low for HT use mainly, and 7Hz at 108db caught my eye!
 

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Discussion Starter · #50 ·

Quote:
Originally Posted by dylanblada /forum/post/14265077


Looks great lemon, I may have to copy you if thats OK


Stupid question:

Any reason you went with 4 seperate boxes and not, say 2 boxes with 2 drivers each? Just seems like wasted effort unless you put them all over your room (to much hastle for me).

How much difference would there be with only two of your subs running?

Also, what BFD did you use? There seems to be two about $50 difference.


My mains can handle everything down to about 30Hz really well (Polk RTi12's with a Carver M1.5-t pushing them) and my Velodyne DPS-12 is OK for what it is, but I want to go quite low for HT use mainly, and 7Hz at 108db caught my eye!


Copy away! (not like it's a real original design
)

I built them in 4 separate boxes so I can run each in a different location in the room if I ever get the inkling to try one of the more advanced sub placement options. With only 2 running (and half the power) there *should* be a difference of 6dB... when I first got it setup one of the connections I had soldered for the RCA to 1/4" plug had broke and I was only getting one channel to the EP2500, I was still impressed with just the two running. The real reason I went with 4 though was that I couldn't find a capable amp to push just 2 of them for significantly less than the EP2500 cost. Once I conceded that I was going to use these drivers with an EP2500 it was only natural to go with 4 of them. For EQ I have the older BFD the DSP1124, and honestly I don't know what the difference is
.


Disclaimer: To be fair I should mention that these subs should NOT be able to go down this low. If you build a set you may not see the same performance out of them that I'm getting. My room must have some seriously help down low, that's the only explanation. In Unibox it shows the sub down ~25dB at 10Hz. In my room there was a very large spike centered at 45Hz and everything below that spike was flat down to 7Hz so I applied the EQ at 45Hz with no boost down low. I still haven't figured out if that spike was room related or if that was just the natural FR of the sub with a couple nulls around 60Hz and 70Hz. I probably shouldn't worry about it too much though, flat to 7Hz at 108dB is nothing to sneeze at
 

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Discussion Starter · #51 ·

Quote:
Originally Posted by Erich H /forum/post/14265074


I'm also wanting to build this type of box for the 13ov.2, but I'm just not sure if I should keep the same size boxes that you made or not.

Did you get a chance to download WinISD or Unibox and play around yet? I think the boxes I built may be a bit too large for the 13ov.2. In a sealed sub if the sub is too small the FR will roll off earlier, a larger box will have a F3 lower (it will play louder at a lower FR) but could be dangerous for the driver (exceeding xmax) at low frequencies. That's why you really need to model it to find the right balance to get the FR you want without pushing the limits of the driver too far.
 

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Yeah, I messed around with WinISD and Unibox (I'm still pretty new to them both) and was wondering if I was doing something wrong. -6db makes sense, I should have known that. I was thinking about doing 2, but then I saw what you did about the price vs. performance gain of doing 4. Well, I'll keep looking for other options too, I would do a Sonotube, but I can't find a supplier around here, besides paying a ton to Home Depot. Thanks, lemon
 

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Discussion Starter · #53 ·

Quote:
Originally Posted by dylanblada /forum/post/14267071


Yeah, I messed around with WinISD and Unibox (I'm still pretty new to them both) and was wondering if I was doing something wrong. -6db makes sense, I should have known that. I was thinking about doing 2, but then I saw what you did about the price vs. performance gain of doing 4. Well, I'll keep looking for other options too, I would do a Sonotube, but I can't find a supplier around here, besides paying a ton to Home Depot. Thanks, lemon

One thing to consider if you do decide the price/performance of doing 4 over 2 is too much to pass up (as I did): MDF and glue are pretty cheap! I was going to do ported but decided it was too much work as I have no woodworking experience. I decided to try sealed (~$50 worth of MDF and glue before finishing) and just try it out to see how it worked. Needless to say I decided the sealed boxes were worth doing the finishing work on but if they had not performed well I was just going to drop another $50 on some ported boxes and decide which worked best (and if that didn't work I was going to try to sell the EP2500 and get something with less power to try an IB array
). May be something to consider if you just can't make up your mind.
 

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Quote:
Originally Posted by lennon_68 /forum/post/14219820


The boxes are made from 3/4" MDF. Each box consists of 4 16"x16" pieces and 2 16"x14.5" to make the final dimension 16"x16"x17.5". I didn't do any internal bracing but if I did it again I would attempt. At the time it just seemed like another hurdle for my first project, but I have plenty of leftover MDF that I could have added a brace to each and still had lots left for "oops" moments. I didn't use any damping in the boxes as they are already a little on the large side for these drivers.


If you haven't done so already you should download WinISD or Unibox and run some models. I did plug in the parameters for the 13Ov.2 and let it calculate the box size for a Qtc of .707 - according to Unibox it would be "ideal" in a 18L box (as compared to the 26L box it told me to put the 13Kv.2 in). The boxes I built ended up being more like 50L though which extends the F3 but can be dangerous for the drivers (at max power from the EP2500 I would be pushing them ~7mm past XMax at 10Hz).

Just to make sure I understand...since your project has inspired me...the height is 16", Width is 16" and depth is 17.5" for each enclosure? I bought four of the same drivers yesterday on a whim. When I told my wife I was going to build my own subwoofers...she rolled her eyes and asked "why"? Combination of the fact that I am NOT handy and she really didn't see the need to replace my SVS. I laid down the law
and answered "cause I want to." Then ran out of the room in triumph (and fear).



Again, thanks for sharing this terrific first timers notes and project. Until I read your thread, I hadn't really considered jumping into this arena.


Ron
 

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Discussion Starter · #55 ·

Quote:
Originally Posted by rboster /forum/post/14268323


Just to make sure I understand...since your project has inspired me...the height is 16", Width is 16" and depth is 17.5" for each enclosure? I bought four of the same drivers yesterday on a whim. When I told my wife I was going to build my own subwoofers...she rolled her eyes and asked "why"? Combination of the fact that I am NOT handy and she really didn't see the need to replace my SVS. I laid down the law
and answered "cause I want to." Then ran out of the room in triumph (and fear).



Again, thanks for sharing this terrific first timers notes and project. Until I read your thread, I hadn't really considered jumping into this arena.


Ron

That's correct, the 17.5" is the front baffle side. I don't know the "correct" way to do it (if there is one) but I glued (and screwed, I didn't have any clamps) the two 16"x16" pieces with the two 16"x14.5" to give me a 16"x16" square that was 16" tall. I then capped that off with two more 16"x16" - one of them being the baffle to give me the final dimension of 16"x16"x17.5"
 

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Thanks Lennon and Dan:


The typo of 14.5 threw me off....I thought it was a typo, but didn't want to assume anything. I got the drivers (within a week of the order). I would love to find another good plate amp special like the discountinued NHT one's....but it would seem I'm headed towards the prof. amp route.


Again, thanks for the info and follow.


Ron
 

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Discussion Starter · #60 ·
I got the "finish" on - truck bed liner from Walmart - and got the quadruplets back into the house this weekend. I was doing some tweaking and got some results that I would like to believe are accurate... I don't think this can be correct though (see attachment). I figured I'd post here to see if anyone can help me figure out what I'm doing wrong. I'm using REW with the digital Radio Shack SPL meter. I have the SPL meter set to C-Weight and C-Weight SPL meter checked in REW. I also have the .cal file loaded (I'm not double-dipping here using C-Weight and a .cal file am I?). I did calibrate the sound card too but that's only down 4dB @ 2Hz so I know that's not the culprit here.


The other thing I think may be "cheating" the numbers for me is with the really low 7-10Hz notes the drivers make an audible noise, similar to what is being described here: http://www.avsforum.com/avs-vb/showthread.php?t=1046386 I'm concerned I may have some major leaks. I know one of the gasket rings is leaking a bit because when I play the Saturn V taking off track someone posted in the subwoofer forum the screw holes on one of the subs actually whistle!


Any tips or tricks to diagnose and locate leaks? How about sealing up the gasket better? I'm thinking maybe just try re-seating the driver on the one that's whistling and if that doesn't work looking for some small rubber washers.


Any help would be appreciated! Like I said I wish I was really getting 125dB @ 8Hz but I can't believe that's actually true... more things should be falling off the walls if that was the case!
 
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