# Novices first leap into DIY speakers



## Moonfly (Aug 1, 2008)

Ive been doing subs for a bit and decided I would take a stab at speakers. Really its more than that as I want to eventually really build some worthy high end speakers, but there is so much to learn and a fair bit more involved than there is with subs, which are really much more simple comparatively.

So, I have decided to start with this kit from CSS. I want to build something usable with these, but for a final design to be the end of the journey with this kit. Initially I want to experiment a bit and learn as much as I can from a pure beginner POV. 

I have decided to mirror the design of my current speakers, and make some speakers that could be used as surrounds or mains. They are more of a style speaker than a real heavy hitter, but I figured that will be a better place to start and be better for this kit. My current speakers are Monitor Audio R270's, so the first design I have come up with is this:

















I'm going to build these from 1" MDF to give the slim design weight and stability. 

If anyone has any input, recommendations, or advice, I'm all ears :T


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## Dale Rasco (Apr 11, 2009)

I'll be following this one closely Dan as I to want to build my own speakers. Good luck! :T


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## zero the hero (Feb 24, 2008)

looks like a good start, although i dont know if i'd put the tweeter so far from the woofer - you'll get more off-axis nulls that way. Although at those frequencies doesn't matter much.


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## Moonfly (Aug 1, 2008)

I can move it closer no problem. I was toying with putting it to one side to create a left and right speaker, but it can go where ever is best. I put that gap in (30mm in that design) so as no to weaken the baffle too much. As I am doing it out of 25mm MDF I guess I am being a bit paranoid due to only having ever built subs.

Do you think 10mm would be close enough?


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## fbov (Aug 28, 2008)

I'm not familiar with the CSS line, so I thought I'd take a look:
"This kits adds the ERT26 to the EL70 and allows it to fill in the top which some people like over the EL70 by itself. A single capacitor rolls the ERT26 off at about 10KHz and a choice of 2 resistors allows the level of the tweeter to be adjusted to taste."

That's a full range speaker running wide open with a tweeter on a cap to fill in the highs. Very low on the sophistication scale, and at a price that could buy you a very well received MTM. 
http://www.parts-express.com/wizards/searchResults.cfm?searchFilter=tritrix

At the same time, assuming quality drivers it should sound fairly good, and there's nothing wrong with starting with a simple design. Driver placement is an input to crossover design, so without a crossover, there's no external restrictions. Good practice dictates drivers are placed close to one another, and aligned vertically for uniform horizontal dispersion. 

Box internal dimensions can be smaller than external, so small boxes can be made into towers. If you want a port, you should get one of the box modeling simulators (I use Unibox, WinISD is also popular). You'll input the EL70's Theil/Small parameters and the box volume and the simulator will calculate the resulting low-end frequency response. You then trade off box volume and tuning frequency to get the bass roll-off you want. 

However, beware internal shapes that look like pipes - your sketch looks more like a transmission line enclosure, and that's a bit advanced for a first design. (Note the Tritrix towers are TLs, but it's a proven design.) 

Also, plan to line the interior sides away from the port with an open cell foam (or purpose built acoustic absorber) to absorb internal reflections. 

1" MDF is overkill in a narrow tower, but it won't hurt. 

Now, if you haven't committed to the CSS kit, let us know. There are a lot of options. 

Have fun,
Frank


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## 1Michael (Nov 2, 2006)

+1 For the Tritrix. I am a bit of a fanboy for the classic series having built this... http://www.hometheatershack.com/forums/diy-speakers/18814-budget-8-dayton-classic-mtm-rocks.html


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## Moonfly (Aug 1, 2008)

OK, some info for you guys.

Ther CSS kit was chosen for its simplicity, and for experimentation for my first foray into DIY speakers. I already have the kit, and there is basically nothing in the UK for DIY, and this kit is cheap to import, which is important for me as a beginner that could mess this up.

The cab design is based on a WinISD model I already did. I'm aiming for 10 litres and that cab in the diagram is about 11 and a quarter before displacements. The port is 10mm x 100mm and about 160mm long, so its a bit shy of a TL. I plan to add some pyrosorb (acoustic closed cell foam) to the bottom and will do exact calcs for the volume, then add in MDF block to the bottom which will add low down mass and reduce the cabinet internal volume to exactly what I need, and the pyrosorb will goon top of that. I was then thinking of putting some polyfil inside to help with any resonance issues. IIRC, the first port resonance is at about 2.5khz according to WinISD. This flags up as an issue to me but on the flip side I kinda of want to hear this so I gain experience.

There is no crossover, and it is very simple, but that was the idea to begin with before moving up the ladder. If I can get something good from this, then I will be a happy bunny. If there is anything I'm doing badly though, shout out :T

Ive attached a better picture of the port.


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## GranteedEV (Aug 8, 2010)

Is it supposed to be a mass loaded transmission line? Do you have Martin King's worksheets?

Anyways with that thin baffle, I presume you will end up with tons of step loss. You will need to compensate for this, either with a passive filter or a digital boost with a DCX. Even though it's a full range driver, it likely won't have much bass below where the baffle step kicks in. Otherwise your best bet is to load these right up against or inside a wall.

I also recommend considering not making a tower at all. that way you can actively implement a bass woofer like an SDX-7 or JL 8W7 later on. Make it so that it'll work well atop a pair of bass stands 

For the box a few things are highly recommended:

-Flush Mounting
-rounded edges 
-low Q - something like .5


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## Moonfly (Aug 1, 2008)

My intention is only that it is a ported design to extend bass performance, with a simple port giving a tune point. Ive not studied TLs so cant really comment technically on comparisons between standard ports and TL designs. This is not intended to be a TL design, and as far as I was aware, it isnt?


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## Owen Bartley (Oct 18, 2006)

Well now you've gone and done it Dan. Asking for open advice will get you a pretty wide range of input (all good input, I'm just saying there will be a lot). I think if you're partial to this design to match some existing speakers, and already own the kit, focus on the things that can just improve what you have like moving the tweeter closer to the woofer (many designs even overlap the basket slightly to get as close as possible to a point source without going coaxial). Internal damping material to me is more trial and error than exact science, but generally lining the internal walls with some acoustic foam, fiberglass, or something similar will get you some benefits. I haven't done any port calculations for you, but I see you have rounded it over which is a good idea.

It looks like you're off to a good start, and I'll be watching to see the results. Good luck!!


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## Moonfly (Aug 1, 2008)

Ive been playing with the model again a bit here (not bought the materials yet), and I have come to realise something. This design works perfectly, exactly as it is, but sealed. Once I add the 80hz HPF the AVR will add, the response of the sealed and ported cabs will be the same, except of course the sealed one will probably be the more accurate. I think what I will end up with here is a speaker that can be run sealed as a surround, or have its port unplugged if I say wanted to use it as a front speaker in a smaller room setup. I would need some sort of HPF building into the design for these to be safely used as full range, but its doable I think, which should give me some options to play around with their use, and extend their usefulness as a learning project.

My next obvious question is, where do I start designing a HPF for the low end, that I could either place inside the cabinet, or separately perhaps in line in the speaker cable.


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## bambino (Feb 21, 2010)

I just found your thread Dan and am excited to see your outcome, i like the layout and box design. Looking forward to watching this one grow.:T


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## Moonfly (Aug 1, 2008)

Well I thought I would start with something simple to get me off the ground, so hopefully it will all go smoothly.


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## bambino (Feb 21, 2010)

Moonfly said:


> Well I thought I would start with something simple to get me off the ground, so hopefully it will all go smoothly.


That is probly the approach i should have taken but i tend to be one that goes against the grain. My entire project is hidden up in my head so far other then my crossover layout which looks very intimidating even on paper, i'll really start my second guessing of what i am getting myself into once all the components arrive.:yikes:

I look forward to seeing your project unfold as i still have abit of a wait on all my stuff to arrive.:T


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## Moonfly (Aug 1, 2008)

As this is a CSS build, I have decided this thread should be in their forum.

You can continue to follow the build here:

http://www.hometheatershack.com/forums/creative-sound-solutions/37541-el70plusert26-kit-build.html#post332267

I have re-done the model to be fully accurate now. I have taken the advice of getting the tweeter and driver much closer together, which you can see if you follow the link :T

I will close this thread now.

Cheers


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