My Dual 15" Dayton HO How should I build it Thread? - AVS Forum
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post #1 of 87 Old 11-02-2012, 06:47 PM - Thread Starter
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I want to start off by saying this subwoofer or these subs are wife approved, atleast somewhat. When I brought my THT home my wife almost killed me. This time I kind of ran it by her. With that being said I'm a builder coming out of the closet ready to build my first true DIY sub(one that someone else didn't desing, sort of).

I was thinking of building either a single dual 15" ported sub or 2 single ported subs. I'm 95% sure I'm going to build 2 singles unless I"m convinced otherswise?

I don't have much experience with driver parameters and what they mean or WinSD, so I'm hoping to read up tonight and find other builds that us the HO. So if you have a good HO build thread please post it.

My first question is what is a good tuning frequency to start with using these subs.
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post #2 of 87 Old 11-02-2012, 07:41 PM
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since it is a 50/50 performance/waf build:

5 cubic feet net internal
20 hz tuning
2 x 4" ports (flared) 31" long

the shape of the enclosure doesn't really matter so long as the net internal volume doesn't change.

inuke 3000dsp for power and high pass filtering.

best,

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post #3 of 87 Old 11-02-2012, 07:47 PM - Thread Starter
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Does the flare in the ports matter, I was thinking of using PVC. Thats probably the only thing I could use given the length I guess. How many braces would you suggest? How much do I have to work with as far as the 5 cu ft. Say if I can't calculate the brace right because of the holes in it? I bet I sound like a total newb, lol.
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post #4 of 87 Old 11-02-2012, 08:01 PM
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"Does the flare in the ports matter"

sure. it cuts down the point of chuffing. http://www.subwoofer-builder.com/flare-testing.htm

"How many braces would you suggest?"

a simple 1x2 mounted from the center of each panel that is larger than 12"x12". in other words, use a simple stick brace where ever you have a panel that is larger than 12"x12" with no bracing on it.

"How much do I have to work with as far as the 5 cu ft. Say if I can't calculate the brace right because of the holes in it?"

don't worry about it. a few stick braces don't take up much room at all.

outer dimensions of 18"x20"x36" will net you about 5 cubic feet internal and allow you to run your ports with no bends.

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post #5 of 87 Old 11-02-2012, 08:12 PM - Thread Starter
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1x2's that's great it cuts down the amt of work in building the sub.

Do both ends of the ports need to be flared?

I don't want a super long sub so I will probably curve the ports up.

Should I use MDF, or Birchplywood, or something else and how thick would you suggest?
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post #6 of 87 Old 11-02-2012, 09:33 PM
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"Do both ends of the ports need to be flared?"

turbulence in your sub will be less audible than outside. as to how much it matters, who knows?

"Should I use MDF, or Birchplywood, or something else and how thick would you suggest?"

3/4" plywood would be just fine, the more layers the merrier. mdf is fine, but it is hard on tools and your lungs.

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post #7 of 87 Old 11-03-2012, 03:24 AM - Thread Starter
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If I chose to go with a slotted port are there any rules of thumb for not getting port chuff. I've been using WinISD pro and a box calculator from to figure out what the length and width needs to be. I calculated that I should be able to do a port that is 17" X 1.75" and about 30" long. Would the 1.75" Height of the slot port cause chuffing.

Also I'm using Winisd and when I use the files from the shack for the HO and HF driver, the graph shows the HF dominating in SPL, I thought the HO was suppose to be the one with higher SPL's, maybe I'm doing something wrong.

If I wanted to build the box 6 cu ft and tune to 18hz would this cause any sound quality issues or would it just be sacrificing DB's for LF?

I stayed up late but learned a lot tonight. That Winisd is pretty sweet.

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post #8 of 87 Old 11-03-2012, 11:00 AM
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"If I wanted to build the box 6 cu ft and tune to 18hz would this cause any sound quality issues or would it just be sacrificing DB's for LF?"

just sacrificing DB's for LF as you said. that is the tradeoff that i was talking about.

"Would the 1.75" Height of the slot port cause chuffing."

the rough rule of thumb is 17 meters/second at around 20-25hz (rear port air velocity in winisd), but there are folks with higher velocities that don't complain at all.

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post #9 of 87 Old 11-03-2012, 11:04 AM - Thread Starter
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I'm almost ready to begin designing the panels.

Does the size of the enclosure affect sound quality, if I opt for 6 cu ft and 18hz tuning will that make the sub sound boomy?

Would I even truly notice the extra 2 DBs in lfe from going bigger and tuning lower?
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post #10 of 87 Old 11-03-2012, 11:43 AM
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Quote:
Originally Posted by Evolvo View Post

I'm almost ready to begin designing the panels.
Does the size of the enclosure affect sound quality, if I opt for 6 cu ft and 18hz tuning will that make the sub sound boomy?
Would I even truly notice the extra 2 DBs in lfe from going bigger and tuning lower?

My bet is that you would notice the extra 1 cubic foot the most, then the 2dB, then the 2Hz in tuning.

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post #11 of 87 Old 11-03-2012, 11:45 AM - Thread Starter
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So in other words just forget about it, probably not worth it unless I go to 7 cu ft or something.
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post #12 of 87 Old 11-03-2012, 12:14 PM
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"Does the size of the enclosure affect sound quality"

no.

"...if I opt for 6 cu ft and 18hz tuning will that make the sub sound boomy?"

no.

"Would I even truly notice the extra 2 DBs in lfe from going bigger and tuning lower?"

yes, but not a night and day type difference.

each time that you tap on the key of a piano, the lower you go, you can tell the difference. that is the same idea.

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post #13 of 87 Old 11-03-2012, 12:17 PM - Thread Starter
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Just when I was creating the dimensions, now I'm second guessing my size and how deep I want to go rolleyes.gif. You should have just lied to me, Lol
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post #14 of 87 Old 11-03-2012, 12:21 PM
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Evolvo are you building ported subs to go with the THT? Or replacing it?I thought I read it was a bad idea to use ported and horn subs together.
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post #15 of 87 Old 11-03-2012, 12:22 PM - Thread Starter
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The hell with it I'm going 6 cu ft 18hz tune.
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post #16 of 87 Old 11-03-2012, 12:24 PM - Thread Starter
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I'm selling the THT.
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post #17 of 87 Old 11-03-2012, 01:08 PM - Thread Starter
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Ok so dimensions are going to be 30" Tall 20" Wide and 23" Deep. The port length is 32.5".

My panel sizes are Front Baffle 30" Tall X 20" Wide, this is for front and back panels.

The side panels will be 30" Tall X 21.5" Deep.

The top and bottom panels will be 18.5" wide X 21.5" Deep.

I calculated this to be 5.887 Cu Ft with driver volume and port volume. Bracing might bring it down a bit.

Let me know if you guys see any problems with the calculations, I'm about to head to lowes.
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post #18 of 87 Old 11-03-2012, 07:57 PM
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seems like a good plan from over here.

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post #19 of 87 Old 11-04-2012, 02:09 AM - Thread Starter
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Ok, the build is under way but I need a high pass filter and I have no idea, what this really means other than it's something that will roll off sound below a given point and will only allow sound over the HPF.

My question is what are rules or calculations when it comes to what your HPF should be and were do I find this info?

Secondly, what are my options when it comes to getting a HPF? I own a behringer ep2500 and a feedback destroyer, I'm not sure if these can assist me in being setup to be a Highpass Frequency?

Also do you absolutely need a HPF, what if I don't plan on pushing sub super hard?

Is there another term for HPF, because I run searches and don't seem to see many electronics associated with being a HPF?
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post #20 of 87 Old 11-04-2012, 08:28 AM
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below the tuning point of the sub, the driver will "unload" which means that it will behave more or less as though it is in free air and can easily be damaged.

plate amps typically have one built in even if they don't make mention of it.

the least expensive option that i am aware of is the behringer mic2200, about a hundred bucks. it has an adjustable high pass filter that can go down to 10hz iirc. if you tune your enclosure to 18hz, then you will want to place the filter point at or just below that point.

your amp has one built in, but i think it is around 35hz, which is too high for your purpose.

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post #21 of 87 Old 11-04-2012, 09:03 AM - Thread Starter
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I see, that's why you reccommend the Inuke because it has built in adjustable high pass filter. I guess I need an amp anyway, because the behringer I have is not mine even though I've been using it for almost 2 years. I'm using someone's who's sub blew a couple years ago and they haven't take the time to replace the driver.

I'm also wondering would using 1 4" Port cause Chuffing. Winisd shows the port velocity at 6. I was thinking of maybe doing 2 X 3" ports which also show about 6, I kind of don't want to deal with the curve.
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post #22 of 87 Old 11-04-2012, 09:29 AM
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I'd double check, but I believe the HPF in the iNuke only goes down to 20Hz.
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post #23 of 87 Old 11-04-2012, 01:22 PM
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"I'd double check, but I believe the HPF in the iNuke only goes down to 20Hz."

that's right, but you can fudge it a little in combination with the shelf filters.

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post #24 of 87 Old 11-04-2012, 01:26 PM
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"I see, that's why you reccommend the Inuke because it has built in adjustable high pass filter."

yeah...in the dsp models.

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post #25 of 87 Old 11-04-2012, 03:57 PM
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A little hint where slot ports are used.......max suggested height/width ratio is 1:8 so a 2" high port should be no wider than 16".
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post #26 of 87 Old 11-04-2012, 04:03 PM
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"A little hint where slot ports are used.......max suggested height/width ratio is 1:8 so a 2" high port should be no wider than 16"."

that seems reasonable, but do you have any data or a source on that?

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post #27 of 87 Old 11-05-2012, 12:41 PM - Thread Starter
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Ok, so I finished one up last night and man does that bass sound absolutely incredible. Things were shaking that had never shook before and bass was tighter and hit harder, and that was only 1 of the 2. It sounded deep and thunderous. Here's the kicker I had the EP2500 set with the high pass at 30hz and it still rumbled I cannot imagine what's going to happen when I get that fitler down to 18hz.

I used 2 18.5" ports and so far haven't heard any chuffing either. I'm hoping that once I get the lower frequencies I won't hear anything but my port velocity should only be around 8ft per second at max or 2.8 m/s, I thinks that sounds right.

One question that I have is exactly what happens if you have no High Pass Filter, how is it that the woofer could burn out. If the DB's are rolling off naturally at 18hz due to box tuning why would the sub reach Xmax. Is there a point at which the air will not be compressed inside the sub anymore and the woofer moves freely. It just seems that the graph predicts a rollof that is close to second order anyway, so I don't understand why the sub could fry? It seems like if the subs can't play below the tuning frequency very loudly why would you need high pass, does the high pass filter just rollofff the DB's quicker the winisd curve shows. With my Tuba HT I never used a HPF.

I'll post pics later.
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post #28 of 87 Old 11-05-2012, 03:36 PM
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Quote:
Originally Posted by LTD02 View Post

"A little hint where slot ports are used.......max suggested height/width ratio is 1:8 so a 2" high port should be no wider than 16"."
that seems reasonable, but do you have any data or a source on that?

Been a rule of thumb for a few decade. Severe compression results.
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post #29 of 87 Old 11-05-2012, 03:47 PM
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Quote:
Originally Posted by Evolvo View Post

Ok, so I finished one up last night and man does that bass sound absolutely incredible. Things were shaking that had never shook before and bass was tighter and hit harder, and that was only 1 of the 2. It sounded deep and thunderous. Here's the kicker I had the EP2500 set with the high pass at 30hz and it still rumbled I cannot imagine what's going to happen when I get that fitler down to 18hz.
I used 2 18.5" ports and so far haven't heard any chuffing either. I'm hoping that once I get the lower frequencies I won't hear anything but my port velocity should only be around 8ft per second at max or 2.8 m/s, I thinks that sounds right.
One question that I have is exactly what happens if you have no High Pass Filter, how is it that the woofer could burn out. If the DB's are rolling off naturally at 18hz due to box tuning why would the sub reach Xmax. Is there a point at which the air will not be compressed inside the sub anymore and the woofer moves freely. It just seems that the graph predicts a rollof that is close to second order anyway, so I don't understand why the sub could fry? It seems like if the subs can't play below the tuning frequency very loudly why would you need high pass, does the high pass filter just rollofff the DB's quicker the winisd curve shows. With my Tuba HT I never used a HPF.
I'll post pics later.

The natural acoustic response of a vented alignment will roll off at that rate but that doesn't mean teh signal has been attenuated. That's what HPF's are for. wink.gif Below Fb the box and woofer unload and the excursion skyrockets.

This is why you have to use a high pass filter:

DaytonHO152010overexcursion.gif

My Dual 18" LLT subs 120dB down to 10hz

 

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post #30 of 87 Old 11-05-2012, 05:58 PM
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"I used 2 18.5" ports and so far haven't heard any chuffing either."

those seem a little short. what diameter? also, post a couple pics. :-)

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