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Discussion Starter · #1 · (Edited)
Hi, I am am new here and just want to say what a great forum it is, I have read up about many peoples projects and I fancy building a subwoofer myself, it will be used for gaming, music, movies and general tv.

Due to the availability of subwoofer drivers in the UK, the two drivers I am interested in are the Ascendant Audio Havoc 15 and JBL W15GTI. I have attempted to use Winisd to model these subs best I can but get stuck when it comes to high pass filters etc. I plan on using a Behringer EP4000 or similar to power it.

I would like to build a ported enclosure, can anyone help me design a suitable box or give me help designing one, and which one appears to work the best. It seems to me that both work well in around 9 to 10 Cu.ft Is it a real problem that the JBL is a dual 3ohm voicecoil and lower power handling than the Havoc?

I only have the free version of winisd, but when adding a high pass which is most appropriate with which settings as when I try to say add one at 18Hz with a 20Hz tuned enclosure the graph is effected both above and below the 18Hz?

Thanks for your help Ian
 

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Hi Ian,

Welcome to HTS :T

I wouldnt use either of the drivers you selected. Its not that they are bad, but the AA drivers are designed for the car audio world and arent best suited to home HT. The JBLs are generally pretty god for the money, but they wont perform as well as some other options out there. Knowing the UK market like I do, my personal choice would be the Fi Q series. Ive used these myself and they are fantastic, and obviously this means I can put you onto their distributor in the UK too :T. The word on the Q vs Havoc is that the Havoc is a slightly warmer sounding driver, but its not quite as articulate as the Q series. You may decide the Havoc is more what your after though, so take my choice as merely my opinion, you still might actually like the Havoc better.

Make sure you have the pro Alpha version of WinISD, as its the best version to use. When you add in a HPF, select Butterworth type and choose either 2nd or 4th order, depending on which is available to you. I can help sourcing that if you need it. If your building a large low tuned sub though (LLT), then a tune of around 15hz will mean you can get away with not using a HPF. If this is the case, then you need not include it in your model.

The EP4000 is a good amp for powering a sub IMO (I have also used these on a few occasions), but do bare in mind they use a fan to cool them which you will hear during quiet scenes. I located mine in a separate room to cure that which IMO is the best solution. Once its setup, you dont need to go to it again anyway.

If you want to look at the Fi drivers, just say and I'll link you to them. Once we know the driver you will use, we can model it :T
 

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Discussion Starter · #3 ·
When I attempted to model the subs in Winisd the Havoc appeared to give a flatter response than the Fi Q15 sub, from reading threads on various forums I thought the aim was to get as flat a response as possible, is this not right? The frequency response graph for the Fi had a dip between what I guess are the resonant frequencies of the driver and the port/box? whereas the AA Havoc was smoother and the JBL was virtualy level.

Should I be looking at "transfer function magnitude" graph or the "spl" graphs? Also i cant go for a LLT as I think it will take up too much room, thanks for your help
 

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Discussion Starter · #5 ·
Thanks for your help, your models look better than mine, not sure what I was doing wrong but mine had a dip in the curve/graph. Althought the Havoc 15 may not be the best driver for HT use does it look as though it will perform acceptably? I choose this driver as it appears easily available, would I notice a great benefit in using a Fi Q15 bearing in mind this is my first HT subwoofer, so I am no expert and will probably be pleased with either?
Thankyou.
 

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Discussion Starter · #7 ·
Thankyou for modeling the subwoofers, I have played around with them, for the Havoc 15 it appears that reducing the enclosure size to 7.5Cuft reduces the output at 20Hz by just over 1dB, would the speaker still be happy working in this size enclosure? or possibly smaller if you think it will not restrict performance too much. I am having trouble persuading the girlfriend that I need a sub in our living room so if I can make it smaller she will be happier, but I dont want to do this at the expense of the performance/sound quality.
 

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Discussion Starter · #9 ·
Can you tell me where I check the air velocity? when I select the rear port air velocity graph, and trace the graph with the cursor it peaks around 114m/s at around 18Hz on the model you gave me, I notice the port dimension is 1x 4" diameter port, when I increase this to 2x 6" ports it drops to a maximum of 25.6m/s at around 19Hz. When i decrease the box to 8Cuft rather than 9Cuft it appears to lower the port speed to 23.8m/s. I am doing something wrong?

Sorry for all the questions and thanks for your help.
 

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Can you tell me where I check the air velocity? when I select the rear port air velocity graph, and trace the graph with the cursor it peaks around 114m/s at around 18Hz on the model you gave me, I notice the port dimension is 1x 4" diameter port, when I increase this to 2x 6" ports it drops to a maximum of 25.6m/s at around 19Hz. When i decrease the box to 8Cuft rather than 9Cuft it appears to lower the port speed to 23.8m/s. I am doing something wrong?

Sorry for all the questions and thanks for your help.
It looks like Mike didn't attempt to properly model the port in the projects he attached (they default in WinISD to a single 4" cylindrical).

You are checking the port velocity in the correct place. You will need to adapt your port parameters based on your planned enclosure, which it sounds like you started playing around with. Mike's advice is sound in that less than 26 m/s is a good design goal.
 

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Discussion Starter · #11 · (Edited)
Ok, thanks, is there any other parameters that I need to be aware of or need to check? Also I have been reading up about port design, I feel that a slot port will probably be the way I will go due to limited sources for 5" diameter ports, although i may attempt to build a round flared port. I have been reading about end correction for ports, can someone please explain simply what this means? and also how it is effected depending on the position of the slot port and the enclosure walls that it is against? Thanks again.
 
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