first project

[audio_noob]

ok. im a student in my second yr at college (uk) and im making some three channel speakers. i know theres a lot of work that can go into designing speakers, but i only need to pass an a level here, not get a masters at uni 😉

my idea is to make a *rough* pentagon shape out of 1 inch mdf, witha slanted bottom inside. there will be a 12-inch driver in the top, with the tweeter and mid range speaker in the front. im not yet the best with CAD yet, so no pics as yet im afraid. i was planning on making them a little over a foot tall and the same in diameter. kind of like a sub (more shape than internals).....i know this is very vague but would there be any major problems with this design?

i was also wondering are there any good sites with circuit diagrams of crossovers? both active and passive. ultimately i am going to design my own, but first i need some research and i want to look at existing products. any ideas welcome.

cheers

alan

 

[Vikash]

Hi Alan,

but i only need to pass an a level here, not get a masters at uni

Is there a particular reason for the pentagon shape with a slanted base? Just aesthetics, or functional?

First thoughts are that you're taking this road to reduce diffraction/standing waves which is great. But it's a difficult enclosure shape to work with if that's not the case. Considering that each driver will be in its own compartment, do you have any ideas on how you'll split the insides? Some interesting maths coming up

Also, you will need to choose your sub carefully as it can sag over time. Some subs are better than others for upfiring/downfiring (there's a way of estimating the feasibility using TSP's).

We'll be able to help better if we know the drivers you're going to use? Are your thinking sealed or ported?

Overall I don't see any major problems, but rather an interesting enclosure design with potential 😉

 

[audio_noob]

Ok the pentagon shape was an idea, its slightly evolved now. the idea was to diffuse all the standing waves. In the attached picture, the top diagram is looking down onto the speakers, showing the rough shape. (not to scale, its something i quickly whipped up to illustrate the idea)
the lower one is showing my idea for the mid and high range cones(obv!?). is there anything i should be aware of here?

as far as buying the drivers goes....i was going to buy them from CPC, but i havent chosen any particular ones yet. some advice here would be useful too, i know some basics and im very willing to learn the rest 🙂

also a link to some designs of crossovers, if anyone can point me in the direction of one that would be great.

thanx a lot

alan

 

[pinkmouse]

Driver recommendations are totally budget dependant, how much do you want to spend?

The only thing that comes to mind when looking at your design, is that it may be difficult to partition inside for a separate chamber for the mids. As for crossover design, it is a frequently mentioned topic on the forum, I suggest you do a search first, then come back with specific questions. There is lots of good info on this board. 😉

 

[Ap]

The shape you have in mind is most likely going to be as nightmare to wood work, especially being your first project.
I would either just go for a simple pentagon with equal width sides (cutting will be a lot easier), or just make a rectangular box with internal sloping partitions/baffles.

As for the mid tweeter layout a vertical inline placement will give you superior results. Having the bass on top is quite a neat idea, just make sure the cone isnt too heavy to avoid sag.

 

[Vikash]

Ok the pentagon shape was an idea, its slightly evolved now. the idea was to diffuse all the standing waves

It may be better, albeit more laborsome, to use the transverse lamination (translam) technique. Downside is more wood, more waste, more expense. But MDF is cheap anyway.

Using the above, you could simply create a horizontal partition to seperate the sub and mid/tweet.

As for the mid tweeter layout a vertical inline placement will give you superior results.

Not sure I agree with that. Diffraction will be worse if drivers are equidistant from the baffle edges (and may also have effects internally for standing waves)