Dayton 18" HO Ported Build Thread

[Haoleb]

Now I have had a chance to play with the DCX and setup a little bit here are a couple of initial graphs of my in room response. Needs a little work but my setup and placement options are somewhat limited for a little while.

Subwoofers Only. Main speakers muted.

Subwoofers and Main speakers together.

 

[TLS Guy]

Thanks for that post. I suppose that rise from 45 Hz and down is room gain.

It would seem that makes a very effective sub. The response seems more extended than the model. The response does not seem to be falling even at 15 Hz, and I don't understand that given the F3 of the driver.

How do they sound? I hope the bass is good and tight.

 

[lsiberian]

are you using a house curve? Remember to not go overboard with eq.

 

[Haoleb]

No, I have not set a house curve. I read the article on it over at the HTS but it seemed like it was geared more towards an analog EQ with 20 or so adjustments. Not sure where I would start setting a house curve with the DCX..

I should also add that the response with some EQ. On one subwoofer I have -8.7db@56Hz and -5.5@20Hz and on the other I am -10@48Hz and -2.5@90Hz though I am not sure how much that last one is doing as they are crossed over at 75Hz with a butterworth 24db slope at the moment. As far as the subs go that is all the EQ I am using at the moment.

And for sound they do sound very clean. As i stated before I have been very surprised how punchy they can sound for such a large driver. I am currently listening to the interstellar soundtrack I got in 44khz/24 bit and the bass is fantastic. The way of thinking I used to believe that small drivers are fast and big ones are only good for really deep stuff seems like bologna to me. Its really pretty funny to see how much output they have when I look at the driver and it is barely moving. I suspect they have much more to give than I have tried so far.

 

[TLS Guy]

No, I have not set a house curve. I read the article on it over at the HTS but it seemed like it was geared more towards an analog EQ with 20 or so adjustments. Not sure where I would start setting a house curve with the DCX..

I should also add that the response with some EQ. On one subwoofer I have -8.7db@56Hz and -5.5@20Hz and on the other I am -10@48Hz and -2.5@90Hz though I am not sure how much that last one is doing as they are crossed over at 75Hz with a butterworth 24db slope at the moment. As far as the subs go that is all the EQ I am using at the moment.

And for sound they do sound very clean. As i stated before I have been very surprised how punchy they can sound for such a large driver. I am currently listening to the interstellar soundtrack I got in 44khz/24 bit and the bass is fantastic. The way of thinking I used to believe that small drivers are fast and big ones are only good for really deep stuff seems like bologna to me. Its really pretty funny to see how much output they have when I look at the driver and it is barely moving. I suspect they have much more to give than I have tried so far.

Relieved to know there is another happy customer.

You are now correct, the size of the driver has nothing to do with it. It all comes down to the T/S parameters and designing the enclosure right.

There is a common error on these forums that only sealed enclosures have tight bass, and ported ones boom and are no good for music. This is nonsense, you can design for a horrid boomy sealed sub and many commercial sealed subs are. As you have found out a ported sub can be very tight.

The only advantage of sealed is small size, and that comes at the expense of massive power requirements, for amp and driver, because of the Eq required.

Your sub I'm glad to hear is nice and tight. Ares told me that also, so you are number 2. Because your sub is large and does not try and work around the laws of physics, it is highly efficient, will couple well to the room and need very little power, much less than your mains likely. I highly doubt you would run one out of gas, let alone 2 in a domestic environment.

Thanks to your wonderful drawings, this is now a really nice DIY project, producing good results at a very reasonable price.

Thank you once again for advancing this project along.

 

[lsiberian]

I think it was your Kappa thread that started me on the DIY side of audio.

 

[ToddMorrill]

Read this a couple times and I am thinking of trying to do this. Awesome work!


But I have a couple of questions. This is my first time project (uhh ophh), but my buddy is an experienced carpenter who will help me


Couple of parts questions (i live in south america and need to order all)

1. regarding the threaded inserts, can you possible send me an exact link to them and corresponding screws?

2. where did you use the socket cap screws? I think i missed this is this for the driver?


Other qusetions
1. regarding rounding all of the internal holes of the bracings, i couldnt follow the logic? why did you do that again / can i skip

2. so you epoxied the threaded inserts and put PL between the driver and the case right? If you wanted to take the driver out later, could you unscrew and leverage it out with a screwdriver or is this thing set for life?

3. I noticed you said first timers shouldn't try which made me nervous, i guess if things don't quite fit, PL is the secret ingredient? Is that the biggset obstacle, measurement precision?

Super solid work, I am about to get started on my own if you want to follow it, if you think i should try a dumbed down schematic lmk! http://forums.audioholics.com/forums/threads/building-a-sub-box-for-dayton-18-driver-1000watt-inuke.94925/#post-1085505

 

[Haoleb]

You will find some of the answers to your questions here:

http://forums.audioholics.com/forums/threads/build-plans-18-dayton-slot-port.93946/#post-1076296

The threaded inserts and allen head screws were from McMaster-Carr and the part numbers are in that link. The allen head screws were used to hold the driver in place.

I rounded over all the edges inside to minimize any turbulence in airflow and it just looks better. I don't see why you couldn't skip that step. Most people do not do anything near as detailed as what I did and they are perfectly happy.

I epoxied the threaded inserts but the driver itself is just held in with the screws. It has a thin gasket material that is supposed to seal the hole already installed on the driver. It can be unscrewed and pulled back out.

I do not think it is a good build for a first timer unless you are experienced in woodworking and have patience. There are a lot of parts and requires a fair amount of precision and again patience. You could speed up the build with a brad nailer but I was not going for speed with this one. I wanted to build the ultimate cabinet for this driver and a few months later I am still extremely pleased with the outcome of my efforts. PL will fill small gaps better than wood glue but when you have over 40 pieces that need to fit together properly for it to come out as planned that is just a bit much for the skills of some builds I have seen. That's why I would say not for a first timer.

Finally, good luck with the build! If you have questions I will try to answer them. I would suggest downloading the sketchup software and taking apart the box to look at how it goes together and dimension your parts. And of course feel free to change it how you please! This was my second set of subs I built and far and away they are better than my first pair of 12" infinity kappa subs. I think you will be quite pleased.

 

[TLS Guy]

You will find some of the answers to your questions here:

http://forums.audioholics.com/forums/threads/build-plans-18-dayton-slot-port.93946/#post-1076296

The threaded inserts and allen head screws were from McMaster-Carr and the part numbers are in that link. The allen head screws were used to hold the driver in place.

I rounded over all the edges inside to minimize any turbulence in airflow and it just looks better. I don't see why you couldn't skip that step. Most people do not do anything near as detailed as what I did and they are perfectly happy.

I epoxied the threaded inserts but the driver itself is just held in with the screws. It has a thin gasket material that is supposed to seal the hole already installed on the driver. It can be unscrewed and pulled back out.

I do not think it is a good build for a first timer unless you are experienced in woodworking and have patience. There are a lot of parts and requires a fair amount of precision and again patience. You could speed up the build with a brad nailer but I was not going for speed with this one. I wanted to build the ultimate cabinet for this driver and a few months later I am still extremely pleased with the outcome of my efforts. PL will fill small gaps better than wood glue but when you have over 40 pieces that need to fit together properly for it to come out as planned that is just a bit much for the skills of some builds I have seen. That's why I would say not for a first timer.

Finally, good luck with the build! If you have questions I will try to answer them. I would suggest downloading the sketchup software and taking apart the box to look at how it goes together and dimension your parts. And of course feel free to change it how you please! This was my second set of subs I built and far and away they are better than my first pair of 12" infinity kappa subs. I think you will be quite pleased.

Thanks for the follow up and positive review.

 

[mikectm2]

What if this design was built (using 1" mdf ) with just no internal bracing ? ..just a wooden cube, with the slot port of course......

 

[TLS Guy]

What if this design was built (using 1" mdf ) with just no internal bracing ? ..just a wooden cube, with the slot port of course......

1" will make little difference. Bracing is key.

 

[lsiberian]

What if this design was built (using 1" mdf ) with just no internal bracing ? ..just a wooden cube, with the slot port of course......

I would not suggest it. You need bracing for the box to withstand the forces. I also suggest using plywood if you can because it's significantly lighter.

 

[mikectm2]

HI
We're going to throw in about 6 dowel sticks ..for some internal bracing

This woodworker uses that Baltic Burch.

thank u ...why u on a Bridge in Fort Worth ?

 

[ARES24]

You might be able to get away with 6 well attached dowels but you will also require rib bracing as well IMO. 1x3 hardwood running along the long span on edge should help with flex but I can't verify that, it's just the woodworker in me.

 

[Rob Harrison]

TLS and Haoleb,

Thanks to you both for posting the info and experiences. It's appreciated.

I'm about to upgrade my velodyne sub with a DIY sub in my dedicated HT. Was pretty much sold on the ultimax 18, sealed with an iNuke 3000DSP until I read the blogs on the HO 18" ported design. I plan on building the cabinet whatever way I choose to go.

With that, I'm heading down the rabbit hole to join you. Several reasons.... I already have a QSC RMX1450 sitting here from my old band days so I won't need to buy another amp. And... the woofer doesn't need EQ so I won't need to get DSP (either from the iNuke DSP or form miniDSP) saving more money. My pre/pro is an Anthem AVM20 - so I have some control over the crossover point and it has balanced outputs that will make it easy to feed the QSC amp and I have a bunch of cables laying around, saving more money). I'm saving so much money now that I should go spend it... on a new woofer and wood.

I can always do a second woofer, although I don't really have space for one. My room is 13-foot wide, 20-foot long and has 8-foot ceilings.

With respect to bracing and damping the cabinet, it's gorgeous and definitely takes extra work. Wierdos do this kind of stuff hoping it will make a difference - even though it's based on some sound science. And no one but wierdos looking at the construction photos would recognize the extra work.

I'm wierd just like you guys. I overbuild everything. Just ask my wife.

BRACING: I'm thinking the bracing on the HO sub in this thread could be less and much more simple yet just as effective and still allow the use of 3/4" MDF. Benefits would be 1) internal volumes wouldn't be impacted by as much bracing, and 2) the cabinet is lighter. (Understanding that heavy usually connotes "better". In this case, if the bracing and damping is adequate, I don't believe a heavier cabinet would necessarily perform better.) I"m basing this off the principles that columns are much stronger at supporting a load than a beam (although beams definitely have their place, e.g. large open /unobstructed spaces like a house or office space).

In the case of the interior of a subwoofer... having a series of dowels running from side to side will be very effective at damping the sides when using 3/4 mdf. The biggest force/reaction is produced by the woofer itself... running bracing from the baffle to the opposite side would provide significant support to the back wall as well as the baffle and woofer. Particularly if you coincide the columns to accept the driver screws.

This is what the stonehenge design does. You can check it out at diy soundgroup as well as the build by clemsonjeeper on avsforum (I couldn't include the link or address as i"m such a newbie...)

I really like the stonehenge design. But... the wierdo in me causes me to believe that additional damping of the large panels would be beneficial. This is easily accomplished with some dowels or additional MDF pieces tying the sides and existing column braces together. Thoughts? Flaming?

JOINERY METHODS... I have yet to see sub build that utilizes biscuit joinery. I'm a huge fan of it, way better than pocket screws. I subscribe to the tenet that the glue holds the parts together and fasteners are there merely to align, clamp and support the pieces until the glue sets. Biscuits do this very well while being unseen. And they are super easy to install... very forgiving. I use the straight clamp guides for aligning biscuits as they are very handy (and I have no affiliation to the mfr or rockler, but here's where you can get them at rockler. These are great for routing and cutting large panels with a circular saw as well.

PORT LOCATION: I do note that the port on the stonehenge does not open on the baffle, but on a side. TLS mentions somewhere in these build threads that the port should open on the same face as the baffle. Care to comment more on this??? I do recognize it seems intuitive that the port work with the woofer.... is the length of the port set to have the port vibrations in phase with the woofer? If not, that would be bad...

A suggestion on the existing HO build: the port construction could benefit by leaving out the "back" upright piece as it's redundant. Just use the back wall for the port. You would reduce the impact on internal volume and gain a bit back. I do see why the port has the exra piece of mdf on the bottom... as it raises the port opening on the baffle so it's more aesthetic. I like this touch. Also love that you routed the roundover on the port inside the sub. It's all about fluid flow and the reduction of turbulence......

So....I'm not wanting to flame or criticize, but to gain some knowledge from you, and hopefully contribute some of mine so we can all make better subs. Please accept my questions and observations in this light.

In appreciation and comaraderie,

Rob

 

[Rob Harrison]

Just pulled the trigger on the Dayton 18" HO Reference sub driver.....

Haoleb, may I borrow your ranger to go to home depot and get a few sheets of MDF?

 

[TLS Guy]

TLS and Haoleb,

Thanks to you both for posting the info and experiences. It's appreciated.

I'm about to upgrade my velodyne sub with a DIY sub in my dedicated HT. Was pretty much sold on the ultimax 18, sealed with an iNuke 3000DSP until I read the blogs on the HO 18" ported design. I plan on building the cabinet whatever way I choose to go.

With that, I'm heading down the rabbit hole to join you. Several reasons.... I already have a QSC RMX1450 sitting here from my old band days so I won't need to buy another amp. And... the woofer doesn't need EQ so I won't need to get DSP (either from the iNuke DSP or form miniDSP) saving more money. My pre/pro is an Anthem AVM20 - so I have some control over the crossover point and it has balanced outputs that will make it easy to feed the QSC amp and I have a bunch of cables laying around, saving more money). I'm saving so much money now that I should go spend it... on a new woofer and wood.

I can always do a second woofer, although I don't really have space for one. My room is 13-foot wide, 20-foot long and has 8-foot ceilings.

With respect to bracing and damping the cabinet, it's gorgeous and definitely takes extra work. Wierdos do this kind of stuff hoping it will make a difference - even though it's based on some sound science. And no one but wierdos looking at the construction photos would recognize the extra work.

I'm wierd just like you guys. I overbuild everything. Just ask my wife.

BRACING: I'm thinking the bracing on the HO sub in this thread could be less and much more simple yet just as effective and still allow the use of 3/4" MDF. Benefits would be 1) internal volumes wouldn't be impacted by as much bracing, and 2) the cabinet is lighter. (Understanding that heavy usually connotes "better". In this case, if the bracing and damping is adequate, I don't believe a heavier cabinet would necessarily perform better.) I"m basing this off the principles that columns are much stronger at supporting a load than a beam (although beams definitely have their place, e.g. large open /unobstructed spaces like a house or office space).

In the case of the interior of a subwoofer... having a series of dowels running from side to side will be very effective at damping the sides when using 3/4 mdf. The biggest force/reaction is produced by the woofer itself... running bracing from the baffle to the opposite side would provide significant support to the back wall as well as the baffle and woofer. Particularly if you coincide the columns to accept the driver screws.

This is what the stonehenge design does. You can check it out at diy soundgroup as well as the build by clemsonjeeper on avsforum (I couldn't include the link or address as i"m such a newbie...)

I really like the stonehenge design. But... the wierdo in me causes me to believe that additional damping of the large panels would be beneficial. This is easily accomplished with some dowels or additional MDF pieces tying the sides and existing column braces together. Thoughts? Flaming?

JOINERY METHODS... I have yet to see sub build that utilizes biscuit joinery. I'm a huge fan of it, way better than pocket screws. I subscribe to the tenet that the glue holds the parts together and fasteners are there merely to align, clamp and support the pieces until the glue sets. Biscuits do this very well while being unseen. And they are super easy to install... very forgiving. I use the straight clamp guides for aligning biscuits as they are very handy (and I have no affiliation to the mfr or rockler, but here's where you can get them at rockler. These are great for routing and cutting large panels with a circular saw as well.

PORT LOCATION: I do note that the port on the stonehenge does not open on the baffle, but on a side. TLS mentions somewhere in these build threads that the port should open on the same face as the baffle. Care to comment more on this??? I do recognize it seems intuitive that the port work with the woofer.... is the length of the port set to have the port vibrations in phase with the woofer? If not, that would be bad...

A suggestion on the existing HO build: the port construction could benefit by leaving out the "back" upright piece as it's redundant. Just use the back wall for the port. You would reduce the impact on internal volume and gain a bit back. I do see why the port has the exra piece of mdf on the bottom... as it raises the port opening on the baffle so it's more aesthetic. I like this touch. Also love that you routed the roundover on the port inside the sub. It's all about fluid flow and the reduction of turbulence......

So....I'm not wanting to flame or criticize, but to gain some knowledge from you, and hopefully contribute some of mine so we can all make better subs. Please accept my questions and observations in this light.

In appreciation and comaraderie,

Rob

The biggest forces are not from the driver directly. It is the huge pressure forces generated inside the box. Dowels alone will NOT brace a cabinet like that.

It is best to put the port on the front panel. In a properly designed enclosure the phase of the rear speaker output is reversed, so that the port is in phase with the front of the speaker cone.

 

[Rob Harrison]

Thanks for the quick response! Agree that the air pressures are significant. The woofer cone moving is the origin of the force.... it definitely needs to be resisted and is one of the main reasons why we all agree a thick baffle is important. Coupling the woofer from the baffle to the back wall using dowels (aka columns) is the most efficient way of doing this. Haoleb's bracing does this to a certain extent, other than the "ribs" are angled and transfer the axial forces to the angled pieces... not as efficient as a straight dowel would be. I.E. a thinner dowel would need to resist less axial force than an angled brace that now has to resist the axial force that's been transmitted in two axes... it's a simple statics problem.

(Also, in this case, I don't necessarily mean that a dowel needs to be circular in x-section.... I'm planning to use MDF pieces.)

A column (aka dowel) is more suited to the task than a rib (beam), if placed and sized properly, to brace against these forces. A long slender column will buckle, or vibrate in the case of subwoofer, under extreme axial compression. Definitely do not want this. It would need to be sized properly, but would be sized much less than the angle brace to do the same job.

The pressures inside the box... they will alternate from negative to positive. Thus, pushing the sides outwards and then pulling them inwards. The "dowels" or columns are very suited to resisting this, much more than a beam (rib) would be, per volume/mass of the bracing. THis is a difficult thing for me to put into words... I'll need to figure out how to insert pics and draw up some sketches to help clarify my positions.... I don't think we're necessarily saying opposite things.

It's not that the rectangle bracing used by Haoleb isn't beneficial: not only is it acting as bracing to reduce resonances, it also resists racking of the cabinet and aids in construction. Very significant things.....

I am only suggesting the bracing could be more efficient, reduce the weight, increase internal volume, as a refinement on Haoleb's design. Many sub designs I see rely solely on ribs/beams.. not Haoleb's, as his bracing backs up the ribs (beams) with cross connections (columns).

Haoleb... are you using washers on the hex head screws to mount the driver? Mcmaster has black oxidized washers that have a .625" OD. Do you think this will interfere with the driver's surround?

THanks

 

[Haoleb]

Regarding the bracing and using dowels vs what I came up with- First, I am not a mechanical engineer and have not performed any sort of scientific resonance tests or anything on the cabinet. I simply build things which to my own eye look damn strong. I think the reason most DIY builds use dowels or simple cut pieces glued from one side to another is because its just plain easy to do and most of the DIY builders lack the skill or tools (or patience) to do something as intricate. One of my favorite speakers, the B&W 800 uses a similar cabinet bracing scheme to what I have done here- albeit a bit more complex and no doubt they actually tested it instead of just eyeballed it.

My goal was to ensure each and every panel was interlocked together on all sides. With the port I chose to avoid using any of the side panels as a port wall because 1) I just don't like that idea and 2) it enables me to reinforce the areas that did not get bracing (by using double thickness of material) Overall weight was so low on my list of priorities for what I wanted to do with these subs it was not even taken into consideration.

I did not use washers on the driver. The 5/8 washers will definitely interfere, the rubber gasket they glued onto the basket was not lined up properly around the screw holes on either of my drivers and the heads just had to push that gasket out of the way a little bit. The heads on the screws are pretty much the biggest thing you will get in there.

I would have loved to use some fancy interlocking joints on the parts but that was just beyond the time I wanted to spend on these and the skill to do it.

I know there are plenty of folks out there that look at this cabinet and will say it was a complete waste of time and totally unnecessary to have all that bracing but quite honestly... what-ever. This is what I dreamed up and it is what I wanted to build and I did just that and I am still extremely happy 1 year later. Designs like the stonehenge, well it has a lot of columns in one direction but pretty much all of the other side panels are left completely untouched. It does not make sense to me personally to brace the crap out of the front and back but not the sides and leave the port flopping around in the breeze?

That's my take on it. But I look forward to seeing what you will come up with and hearing your impressions!

 

[Rob Harrison]

Yeah agreed withall your points... b&w is not likely to be winging it and like i said... i get the drive to go the extra effort for what may be only a small incremental benefit.

I have the same issuewith the stonehenge, and it would simple to add additional bracing. Also i dont like the port opening location not being on the baffle.

Appreciate these interactins and the efforts u have taken to document your work so others like me can learn and carry forth. In this light, i bring forward the biscuit method for joinery... hoping to expose other diyers to options that havent shown much coverage.
Im at work... typing on my incredibly small phone and will respond more later tonight.
Regards.