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Discussion Starter · #1 · (Edited)
I'm new to this hobby and as a result - even though I've spent a few days reading on topic, some things are still not quite "clear" to me.

Lets look at the following setup. Low budget build. 50%HT 50% music. Dayton Audio SD315A-88 12" driver and Yung SD200-6 200W Class D Subwoofer Amp Module with 6 dB @ 35 Hz ... or Yung 100w no boost.

First question - boost or no boost?

Max box size - 2.37 ft^3 (16" inside cube. - minus driver/vent).

Here's a couple of designs I've came up with.
Orange - Tuning freq 25Hz. f3 at 37.4Hz
Green - Tuning freq 31.01Hz. f3 at 34.33Hz

As far as I understand, I should aim at a tuning freq <30 - am I right?
What about f3? Should I keep it as low as possible?
Air velocity should be <25 m/s or is it <20 ?
SPL? What to look for?

And finally... which one is better - Orange or Green? Or maybe there's better option?

Thanks!
 

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The Yung 100 watt with no boost is your only option with this driver. With it's limited Xmax of 7 mm it can't handle any amount of boost. Here's the project file for it, save it to the Projects folder in WinISD.

View attachment The kehl Project.wpr

Are you wanting a sub for music, HT, or both? What is your budget for a driver and an amp?
 

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Discussion Starter · #5 ·
Thanks Mike! I've looked at your design - the port length is a bit longer that I can fit in 16" (inside size) box.
As far as amp goes - no boost it is than. Thank you. Didn't even think about boost driving Xmax over.

It is for both HT and music. 50-50 I'd say. The budget is 200 max. But the main goal atm is to learn how to design a better box. That's why so many questions. :)

For example - on Air Velocity. In some places they say to keep it under 5% of speed of sound. In some - 10%. Which one is it? Will I hear shuffling above 5% or 10%? Should I look at it at peak or RMS?

Looking at Cone Excursion should I be looking at peak or RMS? And Is it ok if it goes over below 20? (picture shows it at peak)

And other questions from first post :)
 

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For a 4" flared port keep the air speed under 26m/s peak or 18m/s rms.

At some point past Xmax the driver will reach its mechanical limits and bottom out and this can damage a driver. You can exceed Xmax by a few millimeters with no problem. Your cone excursion graph shows you haven't applied the hi-pass filter (subsonic filter) that the amp has. In the file I uploaded look at the EQ/Filter tab and copy that into your modeling.
 

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Discussion Starter · #7 · (Edited)
Got it! Thanks a lot!
So, it looks like Orange one is a better design after all. Even though f3 on orange is higher than on green. Am I right?
 

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I'd also vote orange, less "peaky" and more 20Hz SPL which could rumble a little more.
 

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Discussion Starter · #10 ·
Thanks!

And probably the last question. Does it matter where I put the port? Because it looks like I'll have to put it on the side to fit in.
 

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Rarely if ever would I advise someone to go commercial vs DIY instead of the other way around, but have you looked at just buying the Dayton Sub-1200 for $129? It even goes on sale every now and then for a little less, I think $119.

I advise this because what you are wanting to build is essentially this very sub (same driver, similar plate amp), but to do it DIY would actually be MORE expensive than buying it, and the fit and finish on this sub isn't too shabby, with its large rounded corners, fabric grill, and veneer. I use it with some bookshelves and a receiver for my computer audio system, and although the sub isn't spectacular, for $120, I don't know that it's physically possible to do any better.
 

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Rarely if ever would I advise someone to go commercial vs DIY instead of the other way around, but have you looked at just buying the Dayton Sub-1200 for $129? It even goes on sale every now and then for a little less, I think $119.

I advise this because what you are wanting to build is essentially this very sub (same driver, similar plate amp), but to do it DIY would actually be MORE expensive than buying it, and the fit and finish on this sub isn't too shabby, with its large rounded corners, fabric grill, and veneer. I use it with some bookshelves and a receiver for my computer audio system, and although the sub isn't spectacular, for $120, I don't know that it's physically possible to do any better.
I don't think that the SD315A-88 is the same drive used in the SUB1200. From what I've seen over the years I'm almost certain that the drivers used in the SUB1200 and the like are even cheaper than the low-end Dayton SD drivers. Then you take into consideration the high tuning and small ports on commercial subs, like the SUB1200, it's almost certain that a budget minded DIY project could do better. I'm not saying that the SUB1200 isn't a good value, though...
 

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The OP said he plans on using a 3" port - the 1200 uses a 3" port flared on both ends. The drivers, if not the same, are very similar - stamped basket, small magnet, low xmax. OP is thinking of tuning between 25-31hz, and the 1200 seems to be tuned ~30hz. Going DIY, the plate amp and driver alone are $133.

I'm extremely pro DIY subwoofer, but in this case, I'm just not seeing it. If he stepped up to a higher quality 12" driver, larger box, 4" diameter port, more power, and lower tune, then absolutely, but for what he's aiming at, the 1200 does it cheaper.
 

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Discussion Starter · #16 ·
If he stepped up to a higher quality 12" driver, larger box, 4" diameter port, more power, and lower tune, then absolutely, but for what he's aiming at, the 1200 does it cheaper.
Thanks for advice! Yes, rather often it is easier and more cost effective to get commercial... it's just that I really enjoy DIY. :) Anyway, after a lot of reading and playing with WinISD I did come up with a much better design for the same price.

This time I chose the Infinity Reference 1260w 12-Inch 1200-watt High-Performance Subwoofer (Single Voice Coil)

This is how it looks like using 300W RMS amp, in a 2.63ft^3 box with a 4"-20" port. Box is tuned at 23.6Hz and f3 is 26.1Hz.

Let me know what you think!
 

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