# DIY ZDT3.5 Enclosure Shape



## ovillegas (Jan 30, 2012)

Here is another newbie question about DIY designs:

I want to build the ZDT3.5 from Zaph. I also would like to slightly modify the enclosure for aesthetics.

Here is the question: If I change the shape from "rectangle" to a "trapezoid" shape but leaving the same volume inside by making the enclosure longer to compensate for the shape change, will it change the sound quality of the speakers too much?

What I don't want to do is build this "modified" speaker design and find out I broke every speaker design rule and end up with a really bad speaker.


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## tshifrin (Nov 24, 2011)

The shape of the front baffle might affect the sound a small bit- is that the side you want to change? Other than that, your plan seems okay to me.

Tom


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## ovillegas (Jan 30, 2012)

I was thinking on reducing the size of the back wall a little bit. I plan on the front to stay the same size. 

I just don't like the rectangle look.


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## GranteedEV (Aug 8, 2010)

ovillegas said:


> Here is the question: If I change the shape from "rectangle" to a "trapezoid" shape but leaving the same volume inside by making the enclosure longer to compensate for the shape change, will it change the sound quality of the speakers too much?


It won't make too big a difference if it's just the top part with the tweeter. At worst it'll shift the balance a smidgen if the crossover was made to compensate for diffraction effects. As a positive, the trapezoid shape will have less diffraction effects


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## kadijk (Jan 23, 2011)

I'm no expert, but I have read alot of John's articles and design musings. The baffle on those speakers has to stay the same width, but height isn't critical at all. Other than that, volume would be the next important factor, and then internal damping. I love those speakers, and plan to build them some day. Enjoy the project!


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## ovillegas (Jan 30, 2012)

Another question is, would it be beneficial to line the inside of the cabinet with lead lining? or how about doing double walls and make a cavity in between and fill it with sand?


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## fbov (Aug 28, 2008)

ovillegas said:


> ...If I change the shape from "rectangle" to a "trapezoid" shape but leaving the same volume inside by making the enclosure longer ....





ovillegas said:


> Another question is, would it be beneficial to line the inside of the cabinet with lead lining? or how about doing double walls and make a cavity in between and fill it with sand?


The crossover input variables include baffle width and the location of drivers relative to the baffle edges, and each other. Baffle height and enclosure depth are not variables, and so open to modification within reasonable bounds. 

The questions of wall construction are part of a larger question of how your enclosure design handles extraneous inputs, backwave and driver frame vibration. There are a lot of options; you mention two that potentially address box wall vibration. In my builds, I like to use a combination of constraint layer damping and bracing, but all I use these days are roofing repair sheets, ceramic tiles and scrap wood. It's very effective, as far as it goes. The box still needs interior surface treatment or fill, as required by your design.

HAve fun,
Frank


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## ovillegas (Jan 30, 2012)

Thanks for the input. 

I have a question. 



fbov said:


> In my builds, I like to use a combination of constraint layer damping and bracing, but all I use these days are roofing repair sheets, ceramic tiles and scrap wood. It's very effective, as far as it goes. The box still needs interior surface treatment or fill, as required by your design.


Could you explain how would you use the roofing repair sheets or ceramic tiles? Also, what does exactly "constraint layer damping" mean? 

Sorry if I sound too uneducated, but I'm very new at this. 

Thank you in advance.


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