Need Help for DIY Sub (Dayton Audio HO Reference 18") - AVS Forum
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post #1 of 75 Old 03-07-2013, 09:35 AM - Thread Starter
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Hi everybody...need help in designing a ported box for Dayton HO Reference 18". This is my second DIY sub. The first one was sealed using car sub (Alpine SW-1223D), which proved a fantastic sub esp for music. Even in movies, it has tremendous low and midbass slam but lacks SPL below 30Hz in the ULF region. I can do a ported design for this sub, but decided to go for Dayton that is widely used by so many bassheads around.

Use will be 80/20 for Movies/Music. I have modelled it in WinISD with 9 cu ft box tuned to 18Hz having 3 ports (4 3/8 dia) and 900 watts input power. Port velocity is a tad over 18 m/s and SPL 115dB at 20Hz.

Following are the modelling graphs and require expert insight if they are OK;










HO 18 has low Xmax, but I read somewhere that Dayton Audio guys have been very conservative in the excursion spec and the cone can move till 20mm while still maintaining linearity with 70% BL.

Pls have a look at the graphs and guide if I'm doing it correctly. Thanx

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post #2 of 75 Old 03-07-2013, 12:34 PM
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I'm not seeing anything obvioiusly wrong, and yes, PE's specs for Xmax are very conservative for this driver, based on geometry rather than performance testing such as Klippel.

HAve fun,
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post #3 of 75 Old 03-08-2013, 10:15 PM - Thread Starter
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Thanks for the reply. I was thinking of duals. I have found dual stacked boxes to yeild better performance than putting them in different spots in my room. While later does give even response over a larger listening area but phasing becomes a huge problem between the subs themselves.

So, if I go with dual 18s, should i build 2 seperate ported boxes and stack them or build one tower and house both drivers in it??

For one dual drivers box, should i hook them up internally in parallel for a 2 ohm configuration and use one binding post OR use 2 seperate binding posts and drive each driver at 4 ohms??

Also, how much power do you think will be adequate for these subs to perform to their best in this configuration? I have a Crown XLS1000 and NU6000 DSP. While crown is 2 ohms stable but doesn't have enough juice to drive duals at 2 ohms and iNuke 6000 DSP isn't 2 ohms stable. I can buy another 2 ohm stable amp if the need be.

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post #4 of 75 Old 03-08-2013, 11:45 PM
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you are off to the races!

"I have modelled it in WinISD with 9 cu ft box tuned to 18Hz having 3 ports (4 3/8 dia) and 900 watts input power."

that design is fine. since you have a hang of winisd, you can see how extension and max spl are traded off.

a sonotube type large cardboard tube can be used if you want; a single port 8" diameter should work well for each enclosure. alternatively, a slot port is another option.

18-20mm is definitely a better xmax number to use for that driver in model.

the driver is 4 ohms, which is perfect for your inuke 6000. just put one driver on each channel and set the limiter so that you don't go over about 1000 watts initially and maybe a little higher later if everything is kosher. use this approach whether you use one enclosure or two. one driver per channel on the amp. no bridging.

one or two boxes doesn't really matter except 2 are easier to move around.

don't forget to use the high pass filter for safety.

those subs are going to make a lot more noise than your 12" sealed. that's for sure. :-)

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post #5 of 75 Old 03-09-2013, 12:25 AM - Thread Starter
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Hi LTD02.....thanx for the valuable info.

Sonotubes are beyond me at the moment, I would rather stick with box design only coz I built a sealed and one ported and have confidence I can do it. Moreover, um in Pakistan and don't have much access to such stuff. I ship most of my gear in fact all of it from US including wires. The 2 drivers are on their way and will be here in 2 weeks. Don't ask how much they are costing me eek.gif

I hope 2 of these drivers can belt out some serious shockwaves. Is it fine if I tune the boxes low (around 15Hz) and get away with not using HPF coz I do not want to make the sound chain longer than it currently is. BFD is already in the sound chain along with ART CleanBox Pro. I know signal boosters are not very popular on this forum, but things just do not cut it for at least for me without the ART Cleanbox Pro.

I was inclining towards one tower box housing two drivers only coz that box would fit in the bay window recess in the listening room. Or if requirement be, I can build 2 boxes and stack them in that area. But the size would be huge i.e. 9 cu ft x 2.

I saw designs of Gorilla83 who is using HO18s in dual opposed sealed design and he's using 8 subs in 4 boxes. The FR is unbelieveably flat down to 7hz. Fantastic. If I use that sealed dual opposed design, do you think it will serve my purpose? I want flat response till at least 17hz.

One more thing.....are Peak Limiters on NU6000 DSP for limiting RMS power or Peak??

thanx

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post #6 of 75 Old 03-09-2013, 12:34 AM
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i meant that you could use an 8" diameter piece of sonotube for the port as an option if that was easier.

your nu6000dsp has plenty of options for a high pass filter, so you should be set there. a 15hz tuning is fine if that is what you want to do, but every now and then there are notes that will hit with big power beneath that and if you have a powerful amp such as the 6000, you might get into trouble. it is a precaution that most would take.

if you put both drivers in one enclosure, the enclosure has to be twice as large as your single driver model.

1 driver per 9 cubic feet either way.

how much extension that you get is really based on the size of your room.

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post #7 of 75 Old 03-09-2013, 06:08 AM
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Hello

I have modeled that woofer as well. It seems to do alright in a 8-9 cu f box. Remember if you go with two woofers you must also double the box volume and the port area. There is no free lunch. Also remember that the calculated volume is net volume. You have to add the displacement of the woofer and the ports (including the air inside) to that volume. Also remember that many tubes (drain pipe and such) are dimensioned from the outside. It is the inside diameter you need for your calculations. Just a heads up..

I would advise you to incorporate the filters you intend to use in the model before you build as they have a big impact on cone excursion and port speed. I think it can be done in winisd, but I use “unibox” and “woofer box and circuit designer” for modeling so I am not sure.

I don’t know why you want to go as low as you want, but for most music it really isn’t necessary. A higher tune will give you a little more sensitivity and shorter ports with a higher port resonance. I my model a 20Hz tune looked good. It’s not much of a difference but remember the Inuke does not have filters below 20Hz so if you use a high pass filter you will roll of at 20 Hz anyway.

If you want smaller boxes you can go with sealed. It takes a lot more power but it is much easier to go really low in a box that is not gigantic. You kind of trade SPL for deep bass if you go sealed. Maybe the way to go is trying out a simple closed test box, to see if it will give enough SPL and if not, go ported instead.

Happy building smile.gif

Dan
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post #8 of 75 Old 03-09-2013, 06:32 AM
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Here is what I came up with. Graphs include filters.











Dan
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post #9 of 75 Old 03-09-2013, 07:16 AM
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Here is what two co-located boxes will do with 500W each. I think its safe to assume that this is enough for most people...





Dan
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post #10 of 75 Old 03-09-2013, 10:48 AM - Thread Starter
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Thanx guys for prompt input. Glad to know someone is using Dayton HO 18 in exactly the same box size as I am planning to build.

LTD02, dont mind my ignorance on sonotubes. I can use PVC pipes instead coz that's what I used in another project and it workd very well. With 17Hz tuning frequency in 9 cu ft net volume and 1 driver, I get port length at 46". Maximum port velocity is 22 m/s at 14Hz @ 900 watts input power. Is this correct? My only purpose for tuning low is to get away with not using HPF and keep the port velocity in limits within the audible range (20Hz) at least. There are very few movies, that I know of, that dig this low.

Also could u pls tell me if Peak Limiters on NU6000 DSP deal with RMS power or Peak?? By Peak I mean the sudden burst of power. Also, forgot to mention.....room size is 23L X 16W X 12H with hard flooring and very less damping. Drapes are not that thick either.


Hi Dan
Quote:
I don’t know why you want to go as low as you want, but for most music it really isn’t necessary.

My objective is 80% movies and 20% music, hence the requirement for lower tuning. Since I will be building two subs, stacking them would make up for the lower SPL in depth. I see you modelled your sub for roughly 14mm Xmax @ 700 watts input power though this sub can do 18-19mm with 70% BL and still maintain linearity. Did you do it to account for PEQ filters?? Also, have you already built the box and are you using it?? If so, can you pls post some pics and in-room FR at the LP??

Thanx

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post #11 of 75 Old 03-09-2013, 11:33 AM
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I don’t even have that woofer. I just modeled it to see what I could do with it. I don’t know where the claimed xmax numbers came from so I just used the factory spec. Also I don’t know what xmech is so what you see is a conservative estimate. The graphs include the little boost at 20Hz so it should be safe to use it (if factory spec is correct) and not worry about damaging the woofer. Also I don’t see the point in tuning low if you are using a high pass filter at 20Hz. If you don’t want to use a high pass at all you should be careful and investigate how to use the limiters and maybe the dynamic EQ in the Inuke.- That is if they even work below 20Hz. I just don’t know. I would -not- try to run a ported subwoofer with such a powerful amplifier and no protection at all.

I know it’s not a popular idea around this place, but in all honesty I think many bother too much about the really low frequencies. 20Hz is already very low and if you go even lower you need either a lot of space or very powerful amplifiers and woofers if you want decent SPL. Also in a ported subwoofer a really low tuning is not a free lunch. You give up both some of the sensitivity and power handling further up in the spectrum.

As I said before. If you want to go really low you might want to try the sealed approach first. Either in two boxes or maybe a dual opposed. I model the Dayton to 110db/20Hz in half space in a dual opposed. That IS loud and might just be enough for you, and it is a much easier build. Also the Inuke seems plenty powerful to drive it.

Dan
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post #12 of 75 Old 03-09-2013, 12:41 PM - Thread Starter
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Quote:
Originally Posted by splotten View Post

I don’t know where the claimed xmax numbers came from so I just used the factory spec. Also I don’t know what xmech is so what you see is a conservative estimate.
Dan

I read it here ........ http://www.data-bass.com/data?page=system&id=89
In the same article, the xmech is given as 32.5mm. I don't know if it is one way or two way

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post #13 of 75 Old 03-10-2013, 02:33 PM - Thread Starter
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Let me rephrase...... are Peak Limiters on NU6000 DSP used to limit RMS power or Peak??
What I actually means is do these limiters limit the max RMS power and the peak power (3000 watts @ 4ohms) remains unchanged???

Um not getting any responses, so pls chime in folks with the inuke dsp models.

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post #14 of 75 Old 03-11-2013, 10:01 AM
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Quote:
Originally Posted by braveheart123 View Post

Let me rephrase...... are Peak Limiters on NU6000 DSP used to limit RMS power or Peak??
What I actually means is do these limiters limit the max RMS power and the peak power (3000 watts @ 4ohms) remains unchanged???
Um not getting any responses, so pls chime in folks with the inuke dsp models.

The amp-tests I saw mentioned that you will blow the internal fuse/breaker before reaching the amp's output limits when using both channels. If I recall correctly, it was ~2kW RMS x 2 (real power) they said; which will require a 40amp breaker @ 120v.
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post #15 of 75 Old 03-11-2013, 10:45 AM - Thread Starter
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I brought this amp from US. In Pakistan we have 240V and um using it with step down transformer. I am currently using one channel with another DIY sub at full gates open on 20amp circuit breaker. IThe breaker never tripped.
My question was regarding the Peak Limiters. Do they control maximum RMS power or the maximum peak power? My aim is to limit NU6000 DSP to 900 watts RMS on Dayton Audio HO 18" diy sub coz I modelled it in WinISD and Unibox with this much input power in 9 Cu ft box tuned to 20hz. So when I set the limit to 900 watts, does it mean that the max continuous RMS power will be 900 watts or only the peak will be limited to 900 watts which is used during explsions or war scenes??

Any insight appreciated here coz um confused. Thanx

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post #16 of 75 Old 03-12-2013, 11:30 AM - Thread Starter
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Patience is virtue but anything in access is bad. Can anyone pls answer this;

My question was regarding the Peak Limiters. Do they control maximum RMS power or the maximum peak power? My aim is to limit NU6000 DSP to 900 watts RMS on Dayton Audio HO 18" diy sub coz I modelled it in WinISD and Unibox with this much input power in 9 Cu ft box tuned to 20hz. So when I set the limit to 900 watts, does it mean that the max continuous RMS power will be 900 watts or only the peak will be limited to 900 watts which is used during explsions or war scenes??

Any insight appreciated here coz um confused. Thanx

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post #17 of 75 Old 03-12-2013, 01:31 PM
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Quote:
Originally Posted by braveheart123 View Post

Patience is virtue but anything in access is bad. Can anyone pls answer this;

My question was regarding the Peak Limiters. Do they control maximum RMS power or the maximum peak power? My aim is to limit NU6000 DSP to 900 watts RMS on Dayton Audio HO 18" diy sub coz I modelled it in WinISD and Unibox with this much input power in 9 Cu ft box tuned to 20hz. So when I set the limit to 900 watts, does it mean that the max continuous RMS power will be 900 watts or only the peak will be limited to 900 watts which is used during explsions or war scenes??

Any insight appreciated here coz um confused. Thanx

My guess is that it is RMS, given the complex math required to calculate the definition of a 'peak' on a continuously varying function of both frequency and amplitude.

Since peaks are so quick, it would require a really high sampling frequency or analog circuits, which I doubt the nuDSP does.
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post #18 of 75 Old 03-13-2013, 12:05 AM - Thread Starter
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I guess you are right coz behringer is notorious for the nomenclature they use. I think they should lable it as power limiter and not peak power limiter. Peak is meaningless coz we design sub box to the RMS power of a driver.

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post #19 of 75 Old 03-14-2013, 04:48 AM
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Even though the driver rms maybe 900 watts, thermally it would probably handle 2x that for brief moments. Distortion would hurt the driver before excess power. You want the excess power for head room.
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post #20 of 75 Old 03-14-2013, 02:24 PM
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Quote:
Originally Posted by harleyhualersc0 View Post

Even though the driver rms maybe 900 watts, thermally it would probably handle 2x that for brief moments. Distortion would hurt the driver before excess power. You want the excess power for head room.

I think Ricci put close to 6000watts RMS into a HO-18, for a brief moment above 40hz.
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post #21 of 75 Old 03-16-2013, 02:36 AM - Thread Starter
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Thanx guys for your help. Unfortunately HO 18 went out of stock and wont be available till mid April next month. So, my project is delayed for a bit. However, I need some clarification on air velocity. I modelled HO 18 in 10 cu ft box with 900 watts input power and tuned to 19Hz. The port velocity is having me pull my hair. My objective is to avoid bends in the port and keep it short.



Yellow is port velocity with 8 3/8" size port. Sorry but the colours are not showing correctly in the attached graph.

The PVC pipes we have here are slightly bigger and are rounded off to the lower values, hence the extra 3/8" dia. Anyway keeping every other thing constant and with 8 3/8" port size, I get roughly 34" long port. And if I reduce the dia to 4 3/4", I have to deal with 3 ports of roughly 30 inches lenghts to keep the port velocity below 8% of air speed.

Will going by one 8 3/8" port be better than using three 4 3/8" ports? It will be easier to control the gross box volume with one large port than to account for the extra air volume occupied by three ports for the final box volume that includes bracing also.

One more thing.....By what percentage does falring reduce port velocity?? I mean WinISD doesn't simulate the effects of flaring on the velocity. Is there any program/software that can show this??

I hope I have clearly explained. Any help is appreciated, thanx

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post #22 of 75 Old 03-17-2013, 10:43 PM - Thread Starter
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Come on people.....the prefix to avsforum is www .... help this soul on the other side of world.

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post #23 of 75 Old 03-17-2013, 10:50 PM
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If you can fit the 8" port, you will be fine. You have the port air velocity down to a relatively low level. You will not notice a few % on the air speed when that sub is pumping at a high volume at 20hz.
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post #24 of 75 Old 03-17-2013, 10:52 PM
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both of those are well under 30ms your fine.
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post #25 of 75 Old 03-17-2013, 11:30 PM - Thread Starter
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Flaring, the word is, reduces port velocity. But by how much?? How is it determined how much flaring reduces port velocity by what percentage? I don't get it. Simply flaring the ports is like shooting in the dark. Is there any way to know?

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post #26 of 75 Old 03-18-2013, 06:03 AM
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".....By what percentage does falring reduce port velocity?? I mean WinISD doesn't simulate the effects of flaring on the velocity. Is there any program/software that can show this??"

flaring doesn't reduce velocity. it reduces turbulence at the ends of the port which is what causes chuffing and other noises.

http://www.subwoofer-builder.com/port-flares.htm

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post #27 of 75 Old 03-18-2013, 06:28 AM
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Quote:
Originally Posted by LTD02 View Post

".....By what percentage does falring reduce port velocity?? I mean WinISD doesn't simulate the effects of flaring on the velocity. Is there any program/software that can show this??"

flaring doesn't reduce velocity. it reduces turbulence at the ends of the port which is what causes chuffing and other noises.

http://www.subwoofer-builder.com/port-flares.htm
+1/2. Chuffing is caused by the friction of the air mass against the walls of the port and the turbulence cause by the abrupt transition from the port to the outside air. A flare reduces the turbulence, but not the friction within the port, so for best results you need to keep the port velocity down and flare the exit as well. You can't undersize the port resulting in too high a port velocity and then fix it by flaring the exit.

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post #28 of 75 Old 03-18-2013, 08:50 AM - Thread Starter
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I get it now. Thanx guys for clarification.

One more thing.....just when I was about to order HO 18, it went out of stock. The devil inside says to go ahead with the build coz I can't wait. I can order either two 390HO-4 or 390HF-4 instead. I been playing around with WinISD and both outperform single HO18. I am more inclined towards HO15 coz it can handle more power but has high Fs (24Hz). While the HF15 has lower Fs but cannot be fed more power. Also, HF has huge Vas and calls for a huge cab.

How do both these drivers stack up against one HO18 in dual box i.e. dual HO15 or dual HF15 against one HO18??

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post #29 of 75 Old 03-19-2013, 09:12 AM - Thread Starter
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Ordered dual RSS390HO-4 15" drivers. I modelled them in WInISD with 12 cu ft net box ported to 19Hz having two 6"x30" round ports (1000 watts input power) and they perform better than one HO 18 at least on paper.

I plan on using two binding posts on the box in order to feed them independent signals from both channels of iNuke 6000 DSP. Since the amp is not 2 ohms stable so I can't wire them in parallel. Is this OK??

Also, I' a little confused over the WinISD working. When we model 2 drivers in a box, does WinISD consider if the drivers having single voice coils are internally connected in parallel or series?? Is my model correct?


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post #30 of 75 Old 03-20-2013, 10:53 AM - Thread Starter
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Hi LTD02...... I just stumbled upon your following post;

http://www.avsforum.com/t/1464240/first-subwoofer-build#post_23103133

Pls check the SPL graph of Dayton RSS390HO-4 you modelled. Mine has a huge hump. I punched 550 watts input power. Same frquency and SPL scale, same box size, same tuning, but it's so different from yours. I'm sure I must be doing something wrong. Here is my simulation;



Can you pls have look at the T/S parameters and lemme know what wrong I am doing?? Thanks

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