First DIY sub, Dayton Reference 18 - AVS Forum
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post #1 of 13 Old 03-09-2013, 10:12 PM - Thread Starter
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So, a few months ago I got the bug to do my first full DIY subwoofer. I had built one of the parts-express Dayton Titanic kits before, but I really wanted to make something special this time. After a lot of searching and reading and learning, I decided on what I was going to do and just want to take some time to share my experience in the hope that it can help others. I drew heavily on forums and posts like this to help me with my project. You’ll find a list of links at the bottom to the most prominent such articles.

This subwoofer was to go in a system comprising of all Klipsch Reference speakers (cherry finish). At this point I wish I had manned up and bought the RF-7s, but at the time I couldn’t justify the price. Here’s my component list:

Klipsch Reference:
RC-64
RF-82
RS-52
RB-61 (for 7.1)

Dayton Titanic 12’’ DIY Kit
Pioneer SC-65

The main reason that I wanted to build a second sub was for lower bass response and also to fill out the bass in the room. The enclosure for that Dayton 12’’ driver that they have in the kit is far smaller than it should be and makes it a little punchy. For those who own a titanic driver know that they have no problem with SPL, but are not good at very dynamic bass. They are boomy and not very tight. Due to that I decided to go with the Dayton Reference series since reviews seemed to place them more in the field of tight bass response. I couldn’t choose between a 15’’ driver and the new 18’’ and went back and forth several times. In the end I decided to go with the 18’’ driver, if for nothing else but the coolness factor of a woofer that big.

Since I wanted tight bass response I decided to go with a sealed enclosure, it was also recommended for that driver due to the venting they did on the motor. My next project will be a ported Dayton reference 15’’ HF, however that will be another post when I get around to it. My biggest regret in this project was not knowing about the Thiele small parameters and how they can help guide box size. I went about asking everyone I knew that had built before and kind of hacked together a rough estimate of how large the box should be. I ended up going with a ~3.7 ft^3 box, although I wish I added an extra cubic foot there.

Since the box was going with a cherry set I decided to veneer it and built the base out of 3/4’’ MDF. The final dimensions of the box came out to 21’’x21’’x19’’. I wish I had taken pictures of my plan sketches to put up here, though coming up with a box design is pretty easy.

I have plenty of pictures, however I started a little late in the game. My dad was very helpful in this project; I can’t help drawing on his 20+ years of woodworking experience. We built the enclosure using rabbited joints. We also used a circle-cutting jig for the router that you can find on Amazon or parts-express [link] to cut the hole for the woofer. We glued all of the joints together and since we were impatient we also countersunk some screws into it. The cross bracing we did in a tic-tac-toe style with some 1’’x2’’ hardwood from Home Depot.

The tricky part for us was doing the veneer. It was the first time that either of us had done a veneer project. After doing a lot of reading I decided to go with the 3M NF30 contact adhesive. It was pretty pricey, but according to numerous reviews it is worth the extra money. We used about 1/2 quart for this project. I was completely unaware that it came in two colors and accidentally bought the green version. I highly recommend that you don’t do that as it can show a little on the corners when closely examined.

My mother is an avid quilter, and surprisingly that turned out to be an advantage for us. Cutting veneer with a rotary cutter like they use in quilting was super easy and gave us nice clean edges. It also went much quicker than using scissors or a veneer knife.






The only other somewhat tricky part was building the grill. We used a scrap of MDF that we had left over and cut it down to size. We then cut 2’’ holes in each of the corners and used the table saw to cut out the middle. We ran the router around the edge with a 1/4’’ round-off and in the middle. For the grill cloth we cut 5/16’’ slits down each side and then used the same stuff that they use to put screen into screen doors to hold the grill cloth in place.




I also used magnets to mount the speaker grill to the face and they have been awesome! It makes showing off my speaker so easy, yet I never have a problem with it falling off.

Anyway, the rest was pretty straightforward. Enjoy the pics.










Sorry the pictures of it finished are a little washed out. My theater lighting is not conducive to photos and I had to use a flash. Here’s my full list of speaker parts that I used:

Dayton Reference 18’’ HO Driver
Dayton SPA1000 plate amp
Dayton spike set
AcouStuff fill (2 lbs)
Mounting magnets

My initial impressions were great. It pushes down into the upper 20’s pretty good, but definitely has a sweet spot right around 32-35hz. That aligns with the box since the tuning frequency is 35hz. It works great for movies and most all music. I have a very broad taste in music and occasionally listen to dubstep or electronic music and that is the only time that I wish it could reach a little deeper. However for all rock, folk and indie music it performs like a champion. It definitely rounds out the sound a lot compared to my titanic. Right now I’m running both of them in the front of my system. I need to experiment with placement a bit, but I’m so happy with it now. I watched a blu ray of Skyfall the other night (the DTS-HD MA track) and was just blown away by the output of the sub. It brought a big grin to my face several times during that movie. It is much tighter than the titanic and handles better. It moves so much more air when it engages and therefore is much more impactful on the body than the titanic. It isn’t so punchy, more like a moving wall of air that sweeps you along with it. I’m equally as happy-if not happier-with the finished look. It turned out beautiful and fits right in with my other cherry speakers.

Anyway, I just wanted to share this experience with others and maybe help someone avoid some of the pitfalls that I fell into. It was definitely a fun project and I look forward to more projects this summer.


Useful articles:
Contact adhesive
Veneer
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post #2 of 13 Old 03-09-2013, 11:12 PM
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Great job!
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post #3 of 13 Old 03-09-2013, 11:20 PM
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That sub looks gorgeous! Nice job on the veneer - That's one finish I have yet to try. Do you have any pictures with the grill on?
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post #4 of 13 Old 03-10-2013, 12:56 AM
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very nice work. definitely pro quality there.

the amp likely has a high pass filter around 20hz, most plate amps do (because most ported designs require them and dayton doesn't know if you have a ported or sealed).

as a result, you are likely getting significant rolloff under 30hz.

try setting the parametric eq to freq=20hz, q=1.00, gain=+6db to compensate.

that will help flatten your curve out significantly and move your -3db point from the mid 30's hz to the low 20's hz.

Listen. It's All Good.
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post #5 of 13 Old 03-10-2013, 07:21 AM
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Nice job on the sub. I would really love to see how it responds to low-end eq as suggested by LTD02. I am also building two 9 cu ft ported boxes with HO 18". It will be helpful if you can post some in-room FR with and without EQ, may be a REW response if you are using it.

Thanx

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The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
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post #6 of 13 Old 03-10-2013, 08:19 AM
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Jermeymef, what kind of veneer is that? How thick is the veneer? I have been looking for some veneer for my subs and all I can find at Lowes is the 1/4" Birch and Pine. Did I read your comments right when you said that you cut the veneer with some quilting shears?
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post #7 of 13 Old 03-10-2013, 09:21 AM
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Quote:
Originally Posted by Martycool007 View Post

Jermeymef, what kind of veneer is that? How thick is the veneer? I have been looking for some veneer for my subs and all I can find at Lowes is the 1/4" Birch and Pine. Did I read your comments right when you said that you cut the veneer with some quilting shears?
+1

I'd like to know where you bought it and price per sq ft if possible.

Builds: Maelstrom 21 Ottoman Build, Dual Opposed MFW's x 2, Statements, SEOS-12/TD12M x 5. 
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post #8 of 13 Old 03-10-2013, 12:16 PM - Thread Starter
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First, thanks for all of the encouraging comments! This project has been a test to see if I could build more complex speakers since i've come to love building and designing so much so quickly.

I'll try and respond to all of the comments here in this post.
Quote:
Originally Posted by domanskipaul View Post

That sub looks gorgeous! Nice job on the veneer - That's one finish I have yet to try. Do you have any pictures with the grill on?

Here's a picture with the grill on, the lighting is also a little better for the colors (not much, basement room with little natural light and low theater lighting).


Quote:
Originally Posted by LTD02 View Post

very nice work. definitely pro quality there.

the amp likely has a high pass filter around 20hz, most plate amps do (because most ported designs require them and dayton doesn't know if you have a ported or sealed).

as a result, you are likely getting significant rolloff under 30hz.

try setting the parametric eq to freq=20hz, q=1.00, gain=+6db to compensate.

that will help flatten your curve out significantly and move your -3db point from the mid 30's hz to the low 20's hz.

I must have bumped a knob accidentally because for some reason my parametric eq was set at 25hz, 1.00 and -6db. I've changed the settings but won't be able to crank it for a couple hours, so I'll get back to you when I can test it.
Quote:
Originally Posted by Martycool007 View Post

Jermeymef, what kind of veneer is that? How thick is the veneer? I have been looking for some veneer for my subs and all I can find at Lowes is the 1/4" Birch and Pine. Did I read your comments right when you said that you cut the veneer with some quilting shears?

I did not use quilting shears, but a rotary cutter. One like this. It made the veneer work so easy. I bought the veneer off of Amazon. For my sub since I did all sides I used 2, 2x8 sheets.

Veneer on Amazon
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post #9 of 13 Old 03-12-2013, 07:42 PM - Thread Starter
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So I took some time tonight to play with the parametric EQ settings. Putting that DB boost up to +6 helped a ton. I'm really glad I noticed that it was off like that.

I unfortunately don't have any software/equipment to record in-room freq. response. I'd be willing to purchase some if you guys could point me in the right direction.
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post #10 of 13 Old 03-12-2013, 08:26 PM
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Originally Posted by jeremymef View Post

So I took some time tonight to play with the parametric EQ settings. Putting that DB boost up to +6 helped a ton. I'm really glad I noticed that it was off like that.


What frequency did you boost?
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post #11 of 13 Old 03-12-2013, 09:58 PM
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Quote:
I unfortunately don't have any software/equipment to record in-room freq. response. I'd be willing to purchase some if you guys could point me in the right direction.

REW is free on home theater shack. Learning curve is a lil steep; but since I was able to master it, so could anyone. It is amazing program and helps calibrate the low end in seconds. You would know exactly where and how the bass energy is distributed in your room.

History is written by those who have hanged heroes ...

The best EQ is no EQ ...

Alpine SWR-1223D Slot Ported HT Sub

Dual Dayton RSS390HO-4 Reference 15 Build For HT

Main System: Klipsch RF-82 II, Klipsch RC-62 II, RS-52 II, Onkyo 5010, Rythmik FV15HP, PSB S300
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post #12 of 13 Old 03-12-2013, 10:16 PM - Thread Starter
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Originally Posted by fish323 View Post

What frequency did you boost?

I started at 20 and then pushed it to 25 with q 1.0. Since my f3 is at 35hz I thought pushing up the freq. a bit would help get a reasonable listening level in those mid to high 20's. Since i'm not ported getting all the way down to 20 is impossible. It sounded better at 25, I felt that I actually got more out of the low freq. that way. however, this is going by my ear, to give you accurate results I would have to invest in some equipment
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post #13 of 13 Old 03-13-2013, 11:05 AM
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I am the Dad. I thought it would be good for me to add a few things Jeremymeff left out of the process for those who want to do it yourselves.

1. Rabbeting the sides of the box is a much tighter, longer lasting design, but it requires foresight and a set of drawings. Rabbeting is when a 3/8" x 3/8" piece is cut along the edge of both adjoining edges so they nest together. This creates 3/8" more surface area, for the glue to attach the pieces. We also added counter-sunk grabber screws to strengthen the joint and hold it together until the glue set. We used regular wood glue.

2. Unless you have a mind like Stephen Hawkins, you must draw out your box, with details of the joints in order to get the measurements right. Below are some simple sketches we drew to avoid confusion.


This helped us remember what we were actually building. The numbers at the bottom were the cut list for the sides cut from 4'x8' MDF. 3-21"x21" were for the face, back and backer for the face. The 4-21"x18" were for the sides. These were just rough cuts and we then trimmed down the actual pieces as needed.


This is the detail of which sides needed to be rabbeted.


This showed how the pieces fit together. We purposely cut the rabbet deeper on one side than the other so there was an overhang of 1/16". We cut this off with a flush-cut router bit after assembly and touched it up with a palm sander. It made the box perfectly smooth on all corners.

Each joint was glued liberally, then we drilled pilot holes that were counter-sunk and inserted grabber screws. We also filled the counter-sunk screw heads with filler and sanded them to make a smooth, solid backing for the veneer. The veneer is so thin, any voids could cause the veneer to divot if hit hard.

Using the circle jig to cut the holes was a sweet deal. It is important to brace across the back side of the hole you are cutting BEFORE you cut it out. The router jig pivots on the center of the hole you are removing, so unless it is still connected to the box after you complete the cut, it is like cutting off the branch you are sitting on. Makes a real mess.

We had concerns about the face piece being strong enough to hold the speaker since we only had about 1 1/2" of material left around the edge of the hole and because we also counter-sunk the rim of the speaker, it left only 1/2" of material to bolt the speaker with. We choose to cut another piece of MDF and screwed it to back the face so we now had 1 1/4" of bulk to bolt to. This was cut to slide inside the box when we attached the face piece. It was glued and screwed.


This detail showed how the backing for the face piece fit together along with the rabbet for the speaker flange.


We also inserted T-nuts in the back side of the holes so we could bolt the speaker and amp on with machine screws rather than wood screws or nuts and bolts. Now is it easy to unscrew the bolts and remove the speaker or amp any number of times without damaging the holes or loosing nuts.

Applying the veneer was not that difficult. The important thing to remember is that once you coat both pieces and allow them to dry, if they touch, they stay there, whether it is where you want it or not. We used 2 pieces of parchment paper, one on each half, to separate the veneer and the box. It didn't stick to either surface. We could then move the veneer around until it lined up perfectly, (hanging over the edge 1/8" all the way around the box). We pulled out one piece of parchment and pressed that side down, then pulled out the other parchment and pressed the balance down. It was very slick and easy. The parchment paper is the kind used for baking and can be purchased at most any grocery store. You can also use visqueen, plastic, wax paper or any other semi-slick material. I would recommend using 2 smaller pieces rather than one large piece because it makes the job easier to remove half at a time.

The veneer is VERY thin, only about 1/16" thick. Avoid using a power sander unless you are very, very good or very, very stupid. You can ruin hours of work in about 10 seconds.

The slot for the grill cloth spline was only 1/8" thick and 1/4" deep. The screen spline we used can be purchased at Home Depot or Lowes. There is also a spline roller tool that makes it a snap to install. The corners were cut on a mitre and spot glued to hold them in place.
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