[sub_crazy]

Since it has cooled down a bit I have been thinking of making a ported box for one of my Audiopulse Axis 12" quad coil.

I have done some tinkering in WinISD pro to see if it is feasible. I have already tried 1 in a 1.4 cu ft sealed enclosure and I really like it but these little suckers are power hogs.

I came up with a 3 cu ft tuned to 20hz with a 20hz HPF and about 350 watts of power and it seams to model well but I am still learning WinISD. I get about a 26 m/s peak at 19.5hz for port velocity and the first port resonance is at 265hz. The cone excursion is barely hitting 10mm but if I go with any more power the air velocity shoots up. For a single 4" port the length is about 25" so it seams doable. The F3 looks bad at about 44 hz but the max SPL is in the neighborhood of 117 db at 20hz.

My question is I am sure I messed up somewhere and don't even know if this is a good design considering the F3 so I am hoping the experts out there can tell me were to make improvements or scrap the idea all together and go sealed.

I really just want to compare the sealed and ported enclosures. A friend of mine has also been ribbing me to make a ported as the sealed just made him loopy:dumbcrazy: so he wants to see how crazy this thing can do in a ported enclosure. At first I told him he was nuts but I got the itch to find out for myself.

I have added the WinISD Pro file to download to make it easier. I also added the sticky of Other Downloadable WinISD Pro Files

Thanks in advance:T

 

[Mike P.]

Your numbers are right except for the SPL. I'm showing 105.5 db at 20 hz.

 

[sub_crazy]

105 SPL but 116 Max SPL.

What would you do Mike?

I do have a Mach 5 18" passive from another build I did not like but it didn't seam to model well IIRC.

 

[Mike P.]

I'll take a look at it after work.

 

[Mike P.]

It actually looks good if you have the power for it. 2.3 cu.ft. with 1500 grams added to the PR puts the tuning around 20 hz. With a HPF at 14 hz the PR would reach Xmax with 1000 watts. I'm not sure if the sub and PR would fit in that small a volume though.

 

[sub_crazy]

Hey Mike,

I was actually putting together that same thing as I remember the TC2K project I did. The original enclosure was 2.8 cu ft but I cut large bevels into it as I did not like the look and came up with appox. 2.5 or a bit less so I am right about were I need to be. I actually had it at my office and when I had down time I tinkered with it and added some more bracing which brought the volume down.

Here is the post on that with pics on what I did:

http://www.hometheatershack.com/for...-tc-2000-12-box-suggestions-2.html#post126385

I kept the enclosure in the back of the garage and forgot about it but just dusted it off and will try it out tomorrow and see how it performs. The passive shown in the pic is the CSS but the one I have available here is the Mach 5 which I will try with the AP Axis.

I will pop back in here and let you know how it came out.

Thanks

 

[sub_crazy]

I finally got around to comparing the sealed Axis to the 18" PR assisted box.

It really wasn't a surprise as I figured and I know Mike P. figured the same thing that the PR box played lower, louder and without about half the power of the sealed enclosure. As far as sound quality is concerned they both sound similar except when playing at high levels were you can hear the sealed struggling a bit.

The nice thing about the sealed box though is it is about half the size of the PR box and it still is so impressive in a 1.4 cu ft box. If anyone needs a small enclosure driver that will play balls out then I highly recommend the Axis 12".

The difference between the sealed and PR box was not very big at all for me and I could live with either. I personally tend to like the sealed more only due to the fact that the smaller size makes it more room friendly.

I took a couple of pics before the subs got rolled into the back room. I know the logo on the bottom axis is not straight but I had trouble with those hurricane nuts that I just made new holes and used regular wood screws. I did have the hurricane nuts glued in but one must have worked it's way loose at some point and made life suck for a bit.

The size of the subs does not look like the bottom has nearly twice the volume in the pictures but the PR box is approx. 2.5cuft and the sealed is 1.4. I think the beveled edges on the PR box makes it look smaller too. For those interested the PR box does have Bondo around the end grain and was sealed as it was about to go in for painting when I changed my mind. I am glad I kept the box around though as it sure did come in handy.

Thanks a lot for all your help Mike, you really are an asset to the shack:clap:

 

[Mike P.]

That's a good looking sub, I like the beveled edges. Thanks for posting your impressions, it's not often we get a hands on comparison with the same sub. :T

 

[sub_crazy]

Thanks for the compliment Mike.

I consider it high praise coming from you:T

 

[spanish68]

sub_crazy, nice work! Keep the comparisons coming. I started my build of the PR sub but still I'm waiting for the AV15X sub to arrive. Hopefully, I'll have it done in the next couple of weeks and I'll be able to do some comparisons myself.

 

[sub_crazy]

Thanks Spanish,

I will really be looking forward to your build. Are you going to make a build thread?

I have plenty of drivers to try out but time has not been my ally as of late. I may change direction on a lot of them as well since I heard that TC Sounds might be back with the LMS 18" so I may dump all my plans and just go for a pair of those killers and be done with it.

Have fun on your build:T

 

[lsiberian]

too bad the sale is over on these drivers. I might have done a folded slot port with 1.

 

[sub_crazy]

I wouldn't be surprised to see them go on sale or even closeout as TC Sounds is back branding there own line and it sounds like Audiopulse will be phased out. The Axis is the equivalent of the TC-3000 which I believe will be making a comeback.

Care to share the plans for a folded slot port:bigsmile:

 

[lsiberian]

I didn't model it because the sale ended before I pulled the trigger.

Plus I found a steal on a TC sounds 1000 driver. It's only 2 or 3db less in max volume which is barely noticeable and it requires less power. Plus the slot port doesn't have to be ginormous to keep the rear port air velocity down.

Basically for a slot port you fold the port around the box. It allows you to get low tunes and low air velocity. Plus your distortion is gonna be lower since the air gets out of the port easier. We've got folks that used this design with the Infinity Kappa MidVQ and even at insane volumes they could barely see a paper move that was tapped in front of the port. I've found the design to give the cleanest bass for many drivers.

http://forums.audioholics.com/forums/showthread.php?t=45528 is a link to a very well designed sub using this concept. The box size is around 4.5 cuft and the port is tuned around 22hz. You can see how low the port air velocity is.

After some experience and lots of research I'm fully entrenched in this type of enclosure design.

 

[sub_crazy]

I did model a folded slot port to try on a box I already have. It would basically follow the outside of the box from the bottom to the top.

It is basically the same thing that is shown in the forum you linked except that it will run on the outside of the box due to the box already being assembled.

Thanks for the link. Are you going to post a build thread on your project? I would really like to see how it comes out.

 

[lsiberian]

It along with all of my builds will be documented. I'll post the link when I get started on the sub.

I still gotta get a portable work bench as I got married this summer and the kitchen table is no longer available.