Enclosure Design Review And Feedback Request

[Triticum Agricolam]

Instead of having the port do a 180, I'd suggest just have the port turn a 90 degree turn and then extend along the bottom of your enclosure.

Like DLHgn said, your 45's in the port should be larger to try to maintain a consistent cross sectional area.

Your braces need to be much more substantial. If you want to use scrap pieces they should be at least 3" wide. The wider strips are not only stiffer, but the more importantly, they provide more surface area to glue to.

[DLHgn]

The cross is 3/4x3/4" squares ripped out of the excess plywood. Is that a good idea?

I would suggest using strips that are like 4 x .75".

And would extending the side part of the cross to the port wall help anything?

I'm not sure really. I don't like the idea of a brace putting pressure on the port wall like that but that could also just be me being dumb. I would get a second opinion from someone with more experience for that.

I can get it to hit ~26 Hz just by removing the inner most port wall.

Just be careful with that because you will be increasing the net volume and thus changing the tuning. Also, you might be pushing on the large side for those subs but I couldn't tell you without modeling it. Have you tried putting your box/driver specs in a program like WinIsd?

[DLHgn]

Lol everyone decided to reply at once when I was trying to figure how to do those damn quotes.

[Wasteland_Audio]

For the sake of your listening experience i would suggest tuning no lower than 27 - 28hz. My wall is tuned to 27hz but all i listen to is decaf, rebassed, etc. Anything else sounds horrible. I think you will be extremely unhappy tuning that low.

[Jacob Boyd Bauer]

Even 20 I think would be to low . How you had one tuned that low. Most music wont sound that good

I've had speakers tuned that low. It doesn't sound the best for general play, but when you find something that touches that frequency range, watch out.

Instead of having the port do a 180, I'd suggest just have the port turn a 90 degree turn and then extend along the bottom of your enclosure.

Like DLHgn said, your 45's in the port should be larger to try to maintain a consistent cross sectional area.

Your braces need to be much more substantial. If you want to use scrap pieces they should be at least 3" wide. The wider strips are not only stiffer, but the more importantly, they provide more surface area to glue to.

Why the 90, if you don't mind me asking? Ok. There will be plenty of extra plywood. So I'll make the braces bigger. And the 45's in the port, I know. I find that difficult to accomplish in sketchup, so I was saving that kind of thing for when I move the design to Creo.

And would extending the side part of the cross to the port wall help anything?

I'm not sure really. I don't like the idea of a brace putting pressure on the port wall like that but that could also just be me being dumb. I would get a second opinion from someone with more experience for that.

I can get it to hit ~26 Hz just by removing the inner most port wall.

Just be careful with that because you will be increasing the net volume and thus changing the tuning. Also, you might be pushing on the large side for those subs but I couldn't tell you without modeling it. Have you tried putting your box/driver specs in a program like WinIsd?

I felt the same way about putting pressure on the port wall, that's why I asked. I compensated for the increasing volume when I calculated the effect of removing the innermost port wall and leaving everything else the same. Yes, I'm slightly on the larger side. I haven't done anything in WinISD yet (I've had difficulty with winISD in the past, but it's probably my errors, most people love it), but the manufacturer, which is very trusted and very local says 5-10 cubes each for a ported box. No matter what I do with this box my volume per speaker stays in 8<V<9 (or [8, 9], if you prefer). That being said I think I'm gonna go ahead and try to learn WinISD and do another blank sheet iteration.

[Triticum Agricolam]

Instead of having the port do a 180, I'd suggest just have the port turn a 90 degree turn and then extend along the bottom of your enclosure.

Like DLHgn said, your 45's in the port should be larger to try to maintain a consistent cross sectional area.

Your braces need to be much more substantial. If you want to use scrap pieces they should be at least 3" wide. The wider strips are not only stiffer, but the more importantly, they provide more surface area to glue to.

Why the 90, if you don't mind me asking? Ok. There will be plenty of extra plywood. So I'll make the braces bigger. And the 45's in the port, I know. I find that difficult to accomplish in sketchup, so I was saving that kind of thing for when I move the design to Creo.

A 90 degree turn disrupts airflow less than a 180 degree turn does. Maximizing port efficiency largely comes down to restricting air flow through the port as little as possible.

Also with having the interior port mouth along the bottom of the box your port won't be firing directly at the side of one of your subs, which can sometimes create problems.

[Jacob Boyd Bauer]

Well, this is why I can't stand WinISD (Or manufacturers, whatever)

The only way I can get it to accept anything is to let it auto-populate Fs. Which it does, but it only displays half of what the manufacturer says. Which should I trust?

[Triticum Agricolam]

WinISD is a fickle beast when it comes to entering in driver parameters. Here is the best way to do it:

The suggested procedure for entering driver parameters is following (check first that "Auto calculate unknowns" option is checked):

1. Enter Mms and Cms

This gives fs. If either is not available, then enter fs and other parameter.

2. Enter Sd, Bl and Re

Now, you should get all but Qms (and Qts), Vas. Please note that Vas may not match exactly what is specified by manufacturer, because exact value of Vas depends on environmental parameters. See FAQ.

3. Enter Rms or Qms.

Either one will do, although I tend to prefer Qms over Rms, because it can usually be measured in driver measurement procedures.

4. Enter Hc, Hg and Pe.

If Hc or Hg or either is available, then enter Xmax and optionally either Hc or Hg if available.

5. Enter number of voicecoils.

This procedure is most accurate. Also note that it also calculates true SPL (1W/1m) value. So it might not match the marketing SPL value, which is generally somewhat vague. Not in all cases, though.

6. Correct Znom, if necessary.

If there are several voicecoils, then you must be careful when entering parameters in that case, because many manufacturers give Bl in voice coils in series, because it yields double value for Bl against parallel connection. If driver manufacturer gives Qes, Bl and Cms or Mms, then you can check how Bl is specified. For that, you can enter following parameters to calculate Re: Qes, Fs, Mms or Cms and Bl. Connection mode can be changed by changing the combobox selection. The driver editor then converts Bl and Re values accordingly.

Equivalently, you can check for Bl by entering:

Qes, Fs, Mms or Cms and Re (for desired connection mode).

If you enter resistance for parallel connection and get about half of advertised Bl, then you know, that Bl was specified that way.

Like in Driver-tab in project window, you'll probably noticed the driver icon in bottom of the driver editor window. you can drag the driver object into some project by just dragging the icon.

[DLHgn]

Well, this is why I can't stand WinISD (Or manufacturers, whatever)

The only way I can get it to accept anything is to let it auto-populate Fs. Which it does, but it only displays half of what the manufacturer says. Which should I trust?

Just keep working on it. It was a real PITA for me too but once you get it working properly it can be a life saver and very useful.

[Jacob Boyd Bauer]

Just keep working on it. It was a real PITA for me too but once you get it working properly it can be a life saver and very useful.

Well I got it working (I hope, I wish I could get a second opinion). I'm not sure I'm trusting this software right now, it seems to be going against what everyone was thinking about the design. Tuned to 20 with 15 cubes, the peak is at ~40Hz. The flattest I can get the curve to be in WinISD is a 6 dB increase from 30Hz to 40Hz. I guess if that's anywhere near accurate then that's pretty good, but I feel like this might be inaccurate. Does anyone want to get a second opinion on this?