Dayton 4 DIY Speaker Design

 I made a post here about my Dayton 4 speaker about 4 years ago for a class I was taking. I made this with the idea of the reader having no prior knowledge of speakers. As would be the case for my class mates. I am trying to add more data here that will help people actual trying to build a set.

The design goal was to build a speaker as low cost as possible with a crossover count less than 5 components. The cross over requirement was for a competition at the InDIYana event that year. I did not win the competition. But the speaker surprised many attendees. With less than $30 per speaker and only 4 component crossover it was a win for me.

Specs:

Drivers:            Dayton TCP115-4 and the Dayton ND16 Pressfit

Enclosure:         8” H, 6”W, and 8.5” D, 1/2" plywood.  I added a single brace tying the sides together and zip tied the cross over to it.

Crossover:        Series hybrid 2nd/1st order with tweeter "L-pad" @ ~3800hz

Measured Frequency Response: (Blue is showing inverted tweeter.)

Measured 0, 15 and 30 degrees off axis:

Distortion:

Plus 5db:

Plus 10db:

Crossover:

Please Let me know what I am missing.

How to model enclosures with WinISD

WinISD is a free program that models the effects of an enclosure on a speaker’s frequency response. This is used to design the best speaker enclosure and choose the best speaker for your needs. Ease of use, and the ability to model many drivers and enclosures at the same time makes this tool my favorite. Unfortunately, the software has not be completed. The last update was in 2016. It is still very usable. You can download the program at Linearteam.org 

My friend Johnny Richards did the original guide that I am basing mine off. His guide can be found at http://www.midwestaudioclub.com/resources/winisd-a-beginners-tutorial/

After installing and opening WinISD the first thing to do is add the driver you are going to model to the programs database.

Tip: WinISD come with 1121 drivers already installed. I recommend going to “My Documents > WinISD > drivers” and deleting them all before adding your own. They are outdated and not useful. This will help you to find the drivers you enter easier.

Select the speaker icon to add your speaker.

This opens the driver editor. Under the general tab enter the brand and model of your speaker. You can add comments at this time if you want. I often record the price and what my plans are for the driver. For this example I will be using the Dayton TCP115-4 used in my Dayton 4 build.

Next select the parameters tab. 

Data Sheet provided by Dayton Audio

This is where the Thiele/Small parameters are entered. They are used to accurately model the driver. This is where most new users run into problems. WinISD error checks these values and does not tolerate rounding. The key is to enter the least amount of data that the program needs to calculate the rest. These are Qes, Qms, Fs, Vas, Re, and Sd. I also like to enter Xmax and Pe. All respectable speaker manufacturers provide this data on their web page.

 If it is not available that is a good indicator that the manufacturer is hiding something. Tip: Don’t buy speakers that don’t have this data published. Pay close attention to the units. Most are metric, but some still use the American system. Simply clicking on the units will cycle through all unit types. No need to convert anything! This is one of the little touches that makes WinISD my favorite. I last two tabs are not needed. Now you can save your new driver. The hard, boring part is done.

Now that the driver is in the database we can finally get started. Click on the blank page icon, “Create new project”. Select the driver you just created in the last step.

Click next. WinISD will ask how many drivers. You can have fun with this later.  To start we will only use one.

Click next again. Now it needs to know what type of design. It will give a suggested box type. In this case vented. Tip: closed and vented are the most common and easiest to design. We will be using a vented enclosure so just click next.

Now we get to choose alignment. I often just go with the default choice which changes depending on the driver. These come from pre-computer days when you had to work this stuff out on paper. Since you couldn’t play with tuning the early pioneers came up with alignment formulas that got them close to what they wanted. Now that we use computers this is just a starting place.

Click next and enter a name for your project. Then click Create. Now your screen should look like this:

There is a lot of info presented here. I circled the two main areas on the picture above. First, I am going to go over the lower left side. In the corner there is a colored box titled “Color”. This changes the color of the graph above. This becomes a big deal when you are dealing with more than one driver. Simply clicking on it will bring up a palette to choose your color.

There are seven tabs above “color”. The important ones right now are “Signal”, “Vents” and “Box”.

Box is how big the enclosure is and the tuning frequency. This is where you can decide on how big the box will be and the tuning. This is where the power of using a computer is wonderful. Play with this to see how the graph changes. The goal is to get the lowest frequency response you can; While retaining the same loudness level. Loudness is on the vertical axis. It is measured in decibels. Frequency in hertz is on the horizontal axis. Playing with this will show you how box size and tuning work together. Tip: Click and hold the left mouse button on the image of the speaker and drag to mouse around to change this quickly.

Vents is the number of ports, size, and length. Change the size of the “Vent diameter” and watch what happens to the length. I entered 1.125 because that is what I recommended for my Dayton 4 speaker design in my last post. A larger port would be better but won’t fit in the box! In the screen shot above I changed the graph to “Rear port - Air velocity” by selecting the graph title at the top of the page. More on that later. (Note that port tuning is not quite the same in the real world and could need fine tuning once installed. But this should be very close in this case.)

Signal is all about the amp driving the speaker. The main part is “system input power” This is how much power you can use with the speaker. I am going to set it to 20 watts because that is my amps RMS rating. This affects “Air velocity”, as seen above. And in “SPL” and “Cone Excursion” graphs below.

Excursion is how far the cone moves.

This is a basic overview of this software. And how I used it to model the TCP115-4 woofer used in my Dayton 4 build in my previous post. Playing with the program can help show you how the enclosure has a huge effect on the sound of a speaker. WinISD can help you get the most out of your next speaker build.

Getting Your Feet Wet in DIY Speakers

Preface 

Building speakers is so fun and rewarding. I always get a thrill when I turn on a movie or music and hear my creations again. How awesome is it to tell people “I built that!”? If this sounds awesome then you are in the right place.

In this edition I will outline several ways to get started. What works best for you depends on how deep you want to go. Are you wanting to jump in the deep end or just get your feet wet?

I tried to come up with a step by step plan so anyone can design their own speaker. The problem with this approach is that everyone is on their own path and at different skill levels. So, one plan won’t work for everyone. The best way I have come up with to help the most people is just show how I went about a recent build. This will show you what all is involved. Then you can decide how much you want to undertake. I will also suggest two kits you can buy to make this much simpler. Many people start with a kit. They include everything you need including precut wood so you don’t even need power tools.

Everyone will have a different objective. This guide will not address them all. Instead I will pick one and walk through how to complete it. Even if your goal is very different the steps needed to get there are similar. In this case I have the goal of making very good sounding speakers for $100 or less. These will be used for computer speakers. So, I need them to fit on a desk. Also, I don’t want to have to use a subwoofer do to lack of space and cost.

Goals list:

1.       Small desktop size

2.       Less than $100

3.       Great full range sound

I have three different designs that loosely fit our goals. The first two designs are perfect for anyone that doesn’t want to do wood working. While I love wood working, I know it is not for everyone. Several top designers always have someone else build enclosures for them. They just don’t like to do it.

Speaker kits:

Overnight Sensations

I will start with the one that doesn’t quite fit my goals. That is because it is the most expensive at $138: This speaker was designed by Paul Carmody. It lives up to its name. I heard this at an event where I met Paul. And I have built several of these kits. All the pieces for the box are cut perfectly. It is almost fool proof. I say almost because by brother assembled and painted them – badly. As a tip the box need to be sealed. The edges are rabbited so that the pieces almost lock together forming a sealed edge. How you can leave gaps in the seams is something only my brother could accomplish. Luckily silicone caulk seals very well.  So after a bit of magic they worked fine. 

C-note

The next speaker is also from Parts Express. The C-note kit is the same basic setup as the overnight Sensations. As its name suggests it is $100. I have not used this one. I included it because it has the same goals as I set out.

Dayton 4

Last is my own design. I will outline how I went about it. I will do my best not to lose anyone. Think of this as the Cliff notes version. I will cover the programs I used in detail in future blogs.

I failed at my first attempt to build this. The woofer wasn't up to the challenge. This will happen if you are in this hobby long enough. Later, at a DIY speaker event, I had the opportunity to hang out with two of the people that work for parts express. They were talking about a new driver that they had just gotten in, gushing about it more than anything. And it is only $12. I looked at it and thought of the failed speaker I had given up on. It was a perfect drop in replacement. And it worked wonderfully. Everything seemed to fall into place after that. I call it the Dayton 4. Because I'm really bad at naming things. 

The Drivers

Dayton Audio ND16FA-6 5/8” tweeter – This is a tiny press fit tweeter. Just cut a hole with a 1 1/8” hole saw. Press it in. Done! Frequency response 3500-27000hz.

Dayton Audio TCP115-4 4” woofer – The budget woofer that can do everything. Very easy to design with. Frequency response 53-5000hz

A screenshot of the parts needed for a pair.

The Enclosure

The enclosure is 8” tall, 6”wide, and 8.5” deep. Made out of ½” plywood or MDF. I built a triangle port that caused some minor issues. Instead I recommend a 1.125”diameter port tube 6.5” long installed on the back behind the tweeter. You can find one here.

Test fitting drivers

The Crossover

The crossover is the brain of the speaker. It directs the sound to the correct driver. High frequencies go to the tweeter and lower frequencies to the woofer. This is can make or break a speaker. It is the hardest part to get right. I use a calibrated microphone to measure the drivers once I have them installed in the box. Then I import the results to Xsim. Xsim is a free program for modeling speakers. I used a series crossover. This type of crossover is not used often because they are hard to work with. I this case it worked very well with only 4 components.

Schematic for Dayton 4 Crossover

How do they sound?

Black = on axis. Blue = tweeter inverted.

This is the tricky part. They are my babies; So, I am very biased. They have a great frequency response of 48 – 27000hz. This doesn’t mean anything to most people. But that is very good for any small speaker. And unheard of for one that costs about $30. Treble is airy. Bass is amazing for a speaker this size. Listening to it puts a smile on my face. And that is my ultimate test. 

Cat approved!

All Photos by the author.