18 Sound 15" W750 design ideas? - diyAudio
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Old 27th June 2014, 07:37 AM   #1
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Default 18 Sound 15" W750 design ideas?

I was going to sell these four 15's I have because I was unable to do a project that they were intended for. Now after seeing that there is not any interest in buying these 15's I wondered what would be the best design to use these 15's in?

I looked at doing a TH but never really found any designs I like. I started designing a FLH and they dont look half bad in that. I also thought about trying to design something like the BC415 with the four 15's just because I can. When I say best design I just want a good design outcome with 35hz extension no bigger than something like the BC415.

I wont be moving this cabinet but I would like to try and stay around 1300liters total which is what the BC415 is externally. I know my 15's prefer a larger sealed chamber than the BC's 15's. SO maybe 1300liters internal with all four if possible. If not then a pair of cabinets would be fine. And I would be shooting for a PA design. Extension would be nice to about 35hz. My current design is just a thrown together idea that needs a Hpass at 35hz.

I know there are others out there that can do better in just as small of a space. Just trying to get some ideas of what can be done with these 15's since I seem to be stuck with them. I have a rising response at the beginning because it proved to be quite flat with the 35hz Hpass.

Either way thanks to anyone's help or guidance.

Click the image to open in full size.
Click the image to open in full size.

My simple design will take about 46v to hit Xmax with the Hpass in place. I know the W750's like about 80-95liters of space in the FLH. Like I said these are just what I have on hand and figured why not use them.

Last edited by chrapladm; 27th June 2014 at 07:41 AM.
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Old 27th June 2014, 03:11 PM   #2
sine143 is offline sine143  United States
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i believe the BC 415 uses a different driver (not BC) like maybe the MTX thunder

Anyways, 35hz in 325 L is not going to be pretty. 40hz in 400 liters is still kinda eh.

heres what I sketched up real quick. Stuck to 2 segments as adding a third didnt really do much. Rear chamber is intentionally undersized so that it will flatten out after hipass.
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Old 28th June 2014, 01:48 AM   #3
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Ya I have not gotten any amazing results but keep looking. Will just have to see what volume looks great with this woofer and go from there. If I need more room then I need more room.(volume)

I do want extension but may have to squash the BC size idea.
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Old 28th June 2014, 12:47 PM   #4
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Quote:
Originally Posted by chrapladm View Post
...
I do want extension but may have to squash the BC size idea.
If you want extension go reflex, la JBL (18") SRX700. (SRX728S) Frequency Response (3 dB): 33 Hz - 220 Hz
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Old 28th June 2014, 01:52 PM   #5
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you said you did not find any designs you like for a Tapped Horn.
What about a design like Danleys TH812 or TH412?

Can you post the groupdelay? If its to high at crossover frequency you will get a bad resonant sound and you will need a lower crossover freq.
If this is the case, you can reduce the bandwith with via youre enclouse to get a higher efficiency.

Otherwise, you can fold youre own horn. There enough toturials in our holy world wide web
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Old 28th June 2014, 03:51 PM   #6
sine143 is offline sine143  United States
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Quote:
Originally Posted by Inductor View Post
If you want extension go reflex, la JBL (18") SRX700. (SRX728S) Frequency Response (3 dB): 33 Hz - 220 Hz

Actually, TBH the 728 does not dig very low.

Here's my estimation in hornresp. box sized is undersized due to the drivers massive VAS of 330 liters.

shown is spl at 2.83v for 2 of the the horns, and a single, dual 18 srx clone (using same drivers as srx). The horns are roughly twice the size of the srx.
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Old 28th June 2014, 05:30 PM   #7
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Sine was that horn design using the JBL 18's?

I am wanting to use my 15's I have. Not ideal but I have four of them already. I was hoping for a horn design because I love building them. Ported are easy and I like something out of the ordinary.
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Old 28th June 2014, 05:45 PM   #8
sine143 is offline sine143  United States
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no. the above picture is 2 x 400l FLH with your 15s vs my rough approximation of the JBL srx728 (400 liters net).
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Old 28th June 2014, 05:54 PM   #9
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A Tapped horn is possible to do, but this driver needs a very big throatside to work linear. i think youll need about 500 liters per driver to realize linear response until 40Hz.
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Old 29th June 2014, 12:25 AM   #10
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The bigger this cabinet gets, to hit 35hz, the more I wonder if I should try and sell them again but just for enough money to buy 2 other drivers. I have a pair of 18 Sound NLW9300 also which do much better in horns. I also know those would do well in BFM T48 but do like 35hz performance. Just having six 15's laying around collecting dust has be bored and wanting to build something.

Would be nice to be able to use the four 15's instead but these T/S arent the greatest. 400l is not bad. Although we are reaching the size of the TH18 for a 15". Why cant money grow on trees.
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