First DIY - Fullrange on a €100 budget

[Hugo82]

I'm sorry i should have mentioned that, i was talking about the FE127e Fonken

Cheers

[planet10]

Hugo,

Designed to use 12 & 18mm material, the english units are then generated by the CAD software.

If you don't have a few spare bits of 18mm the front baffle can be doubled 12mm (but you do end up with a 12mm narrower baffle to mount the driver on. The other way to adjust would be to move where the 45 cut-off is and shorten the slot vent piece to end up at the same length (6mm?)

BTW, the best way to achieve the champher is to build the box with and then run the whole box thru the table saw,

dave

[chrisb]

Originally posted by planet10
Hugo,

BTW, the best way to achieve the champher is to build the box with and then run the whole box thru the table saw,

dave

slowly, and incrementally

[Hugo82]

Well, .... 2 months later and i still haven't finished the Fonkens for various reasons.

1st time i jotted down the wrong dimensions for some of the panels ruining some perfectly good wood
Bought some new wood and cut all perfectly to size, was almost done with essembly when my spare time got eaten up by another unforeseen project that was slightly more important so i put it away to finish at a later time.

So i finally had time this past weekend to get going again when i noticed that both cabinets had been ruined by a small leak in the roof right above them and now both are warped and completely crooked

So.... I hope the o'l saying "3rd time's the charm" holds true for me.
But before i get going again i have a few questions.

I'd like to use a different type of wood, birch plywood is the recommended choice for the enclosure but what about solid birch ?
I saw some really nice solid 18mm thick birch wood wich was infact small strokes of slightly differently toned dark colored birch I'm guessing glued together in 1 board.
It looks really nice, even better with a coat of varnish.
Is that suitable for the enclosures ?
I'm not quite sure it was birch but i'll check again tomorrow and take a picture for u guys to see what i'm talking about.

My 2nd question is about the sides of the baffle which are angled back in 45 degrees.
Is that important to the sound or is that just for the looks of the cabinet.
Can i make the cabinet rectangular in shape ?
I'm guessing that i have to shorten the inside of the bass port for the same amount it gets longer to the front so the length stays the same ?
The reason i'm asking is that i can't cut that whole 45 degree angle at once due to limitations on the table saw so it makes the process a bit easier for me.
I also quite like "simple" rectangular designs but I don't really want to change someones carefully designed plans without asking/permission so i'm hoping Planet10 could give me the thumbs up for that.

I'm going to finish up the ruined cabinets real quick (they are dry and clean now) to break in the fe127e's while i start my 3rd attempt.
If anyone has a valid reason why i shouldn't do that then by all means

[planet10]

Sorry to hear about your leak...

Originally posted by Hugo82
I'd like to use a different type of wood, birch plywood is the recommended choice for the enclosure but what about solid birch ?
I saw some really nice solid 18mm thick birch wood wich was infact small strokes of slightly differently toned dark colored birch I'm guessing glued together in 1 board.
It looks really nice, even better with a coat of varnish.
Is that suitable for the enclosures ?

Working with solid can be real iffy, but laminated butcher block tends to be suffer much less with cracking. I've been eyeing some laminated pine & eucylyptus shelving boards for a build...

My 2nd question is about the sides of the baffle which are angled back in 45 degrees.
Is that important to the sound or is that just for the looks of the cabinet.

The big champhers are there for sonic reasons -- they significantly reduce the boxes diffraction signature and help make the box "dissapear". That they look good is just a happy side effect.

Nothing in this box is there by accident.

Can i make the cabinet rectangular in shape ?
I'm guessing that i have to shorten the inside of the bass port for the same amount it gets longer to the front so the length stays the same ?

You can, and that is what you'd do.

dave

[Hugo82]

Originally posted by planet10
Working with solid can be real iffy...

Can u elaborate on that ?

The big champhers are there for sonic reasons -- they significantly reduce the boxes diffraction signature and help make the box "dissapear". That they look good is just a happy side effect.

I see, i didn't know what diffraction was but i guess this picture says it all.



Is that a noticeable effect also to the untrained ears or only when u can compare it with a chamfered cabinet.

[planet10]

Originally posted by Hugo82
[B]

Can u elaborate on that ?

Solid is very susceptable to changing shape with the humidity. Large swings of humidity can cause cracks. A takes a real pro to build a solid wood box that lasts and even those guys have failures. Butcher block solid changes that... still not as stable as plywood thou.

I see, i didn't know what diffraction was but i guess this picture says it all.



Is that a noticeable effect also to the untrained ears or only when u can compare it with a chamfered cabinet.

That could better be called edge diffraction. Diffraction is actually a continuous ohenomenom [f(frequency)], but at low frequencies is sufficiently different in nature to be called baffle step.

The big champher both reduces edge diffraction and smooths out the baffle step.

dave

[Hugo82]

There is be room for the same kind of chamfer at the top of the cabinet... would that be a good idea ?

[planet10]

Originally posted by Hugo82
There is be room for the same kind of chamfer at the top of the cabinet... would that be a good idea ?

It wouldn't hurt, but is less critical, but would need to be accomodated with extra material. Jeff (VinylKid) did this on his variation.

dave

[chrisb]

Based on current use of 15mm (nominally 5/8") material, the chamfer on the side panels of the "prime" Fonken cuts through 3 layers of material for approx 39.5mm depth and 56mm on the diagonal.

You could certainly add a couple more layers of material to top and bottom to allow for chamfers on all 4 edges - just keep the thickness in mind.

what the heck, I have an extra unfinished pair of boxes sitting in my listening room at the moment - I'll probably play with that when I get some time in the next couple of weeks