new to the DIY world...looking for some help / advice... - AVS Forum
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post #1 of 10 Old 11-30-2012, 06:52 AM - Thread Starter
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Just a little background on my DIY skills...almost non-existent...regardless of my diy skills...

I would like to build a sonotube subwoofer enclosure for a 12" sub to replace my current sub (was sunfire true sub mkii...now it is temporarily the bic f12)...my budget is probably around $350 (i know it is not too much...but I am hoping I can do something decent with it)....i would like to move up to a 15" sub but space is an issue as shown below...i want to place the sub in the same location as the bic f12 pictured below...there is nothing really stopping me from placing the sonotube sub in the corner...but even the slightest localization of the sub will bother me...



Question 1...is the list below a fairly complete list of materials needed to complete the project...
- 12" subwoofer (most likely the Dayton Audio DVC310-88...but more on this later)
- 12" diameter sonotube (question on this topic below)
- Amplifier (most likely the Bash 300W Digital Plate Amp as the sub is rated at 350 - close enough)
- PVC for port
- 3/4" MDF
- Terminal Plate or Binding Posts
- Spekaer Mounting Kit
- Damping Material
- Finishing Materials (will figure this out later)
- Wood Glue
- Clamps
- Table Saw
- Dremel (my router alternative)

Question 2....Will 14" sonotube diameter be a better option with a 12" sub due to the necessity of the enclosure's base legs and the enclosure will not have to be as tall?

Question 3...I chose the Dayton Audio DVC310-88 due to the decent excursion and frequency response plot in WINISD (can be seen below)...will this sub be a good choice for a sonotube design...

--- DVC310-88 ---
Power Handling (RMS) 350 Watts
Power Handling (max) 700 Watts
Impedance 8 ohms
Frequency Response 20 to 450 Hz
Sensitivity 87.4 dB 1W/1m
Voice Coil Diameter 2"
Magnet Weight 112 oz.
Resonant Frequency (Fs) 22.2 Hz
DC Resistance (Re) 2.8 ohms
Voice Coil Inductance (Le) 1.76 mH
Mechanical Q (Qms) 8.69
Electromagnetic Q (Qes) 0.40
Total Q (Qts) 0.38
Compliance Equivalent Volume (Vas) 4.25 ft.³
Mechanical Compliance of Suspension (Cms) 0.20 mm/N
BL Product (BL) 15.85 Tm
Diaphragm Mass Inc. Airload (Mms) 259.3g
Maximum Linear Excursion (Xmax) 15.1 mm
Surface Area of Cone (Sd) 502.7 cm²



Question 4...I am fairly certain the answer to this question is "NO" but i will ask nonetheless...should the port volume be subtracted the from the total internal volume of the enclosure...by that i mean if the design requires a 3.2 ft^3 enclosure with a 4" port of length 10.5"...should i add the volume of the port to the total internal volume of the enclosure > 3.2 ft^3 + (3.14 * .33^2 * .875 = .299 ft^3) = 3.499 ft^3

Question 5...What is the general protocol of attaching an end cap to the sonotube?...i believe it is just wood glue between the inner end cap (the smaller end cap) and the inside of the enclosure?...

Question 6...Are screws necessary at all when building a sonotube sub enclosure (aside from mounting the sub to the end cap)?...or is it all just wood glue...
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post #2 of 10 Old 11-30-2012, 10:06 AM
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Hi, I can't answer all your questions as I have never built a sonotube but I'm currently building a ported box.

#3 I'm not sure if it's a good choice or not but there are certain subs to use for a sonotube. It has something to do with the sag of the cone/voice coil. I'm sure that someone will be able to answer this for you.

#4 To calculate AVAILABLE internal volume you take your total internal volume - port volume - bracing volume - speaker displacement. So if you're working backwards and need a 3.2^3 ft. box you'd have to calculate the port volume then add that to 3.2 then add any bracing volume (I don't you need any for a sonotube) then add the speaker displacement volume. This would be the size box that you'd need to build. Be careful as you change the internal volume as it'll change your port tuning. If you're going for a specific tune you might have to add or subtract the length of the port to keep it the same tuning frequency.

BTW, I didn't model your speaker but it seems to me that you might be missing a HPF filter around tuning. When you add that your <20Hz signal will drop much faster. With a ported design you'll need to incorporate that into your model as there is no cone control on a sub below port tuning. I believe the Bash plate amp already has one built into it but i'm not sure at what frequency.


Hopefully, I could help you out somewhat as I'm still a noob myself.
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post #3 of 10 Old 11-30-2012, 01:42 PM - Thread Starter
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i have heard the same thing in regards to the sag...just wasnt sure what it is or how to calculate...hopefully someone will offer their advice...

thanks for answering the question on the enclosure volume...so the volume of the port displacement AND speaker displacement will have to be added to the modeled enclosure volume...because in WinISD...the current port required to achieve the FR above is something like 4 in diameter and ~ 27 in length...

also...by changing the modeled enclosure volume (by adding the port volume / speaker displacement)...how do I calculate the new length of the port...

any input is greatly appreciated...thanks...
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post #4 of 10 Old 11-30-2012, 02:45 PM
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post #5 of 10 Old 11-30-2012, 03:22 PM
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Have you moved your current sub around, say a corner of the room? I'd be surprised if you could localize it, but I don't know your room etc. Placement is super important and can make a huge difference.

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post #6 of 10 Old 11-30-2012, 08:45 PM - Thread Starter
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5242...nice...thanks for the sag calculators and sonosub calculator...i think i am using it correctly...temporarily i have used a dayton reference 12 instead of the DVC310-88 within the sonosub program...



also...i think i am okay in regards to setting up the DVC310-88 as a downward firing sub...the sag calculation returns 3.4 % sag which is within the acceptable range of less than 5 %.

pgwalsh...i have moved the sub around the room...and tried different crossover settings...but i always seem to notice subwoofer localization unless it is upfront near one of the main front speakers...maybe i need to use the audyssey setup on the receiver again with the bic f12 to correct any delays due to sound processing or distance and to setup the correct crossover and for the proper EQ for the main speakers...
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post #7 of 10 Old 12-01-2012, 06:59 AM
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cnp112, as I've stated before it looks like you don't have a HPF filter around your tuning frequency on your model. If you don't, you're going to need to add a HPF. If you do, then you're ok. You'll see that when you add a HPF it could change your model quite significantly (less of a low end).
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post #8 of 10 Old 12-01-2012, 12:31 PM - Thread Starter
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Quote:
Originally Posted by Audiophile1178 View Post

cnp112, as I've stated before it looks like you don't have a HPF filter around your tuning frequency on your model. If you don't, you're going to need to add a HPF. If you do, then you're ok. You'll see that when you add a HPF it could change your model quite significantly (less of a low end).


Audiophile...i see what you mean now...i have added the HPF at 20Hz...the design changes a bit...this may prompt me to make the move to a 15"...but i will have to look into the details of both the 12 and 15...

actually...a little background on what I am trying to achieve...i am trying to place emphasis on low end versus spl...and looking at the design/plot below with the HPF added...i am fairly certain that it should perform much better on the low end response than my current setup....do you think the plot below is pretty decent for low end response...or do i absolutely need to look into 15" designs instead...i feel that response down into the lower 20's @ -3db and below 20 @ -6db should be good...

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post #9 of 10 Old 12-02-2012, 07:46 PM - Thread Starter
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if i were to buy the 4" flared precision port kit from parts express...which is ~ 17" long...and i needed a port of length 23"...can i just use 4" PVC pipe to extend the length...thanks...
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post #10 of 10 Old 12-04-2012, 09:31 PM - Thread Starter
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I was wondering if someone could provide their thoughts on the following project...

I am more concerned with the port air velocity...i understand i will definitely need flared ends for the port...i also understand the air velocity is a bit high...but it is also shown at 300W input signal (max amp input)...

also...can someone let me know if i can use the white PVC pipes at my local hardware store to extend the 4" precsion port kit instead of buying the precision port extension...thanks...

DaytonAudio_DVC31088_375_2025.zip 1k .zip file
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