Enclosure options for Focal 6m115

[NcHalfrican]

As the title says. I can't link the T/S, because I'm on my phone. I'd like to cross it in the 3.5k-4k Hz range. It will be a two way setup with goldwood piezo tweeter.

[NcHalfrican]

Bump

[mdocod]

I suggest against the piezo but understand this is probably for budgeting reasons? Looks like that woofer is priced pretty low so I assume you are aiming for a very budget build.

If you are going to use a piezo, might have a read here: Piezo Tweeter Crossovers | J Risch

Otherwise I seriously suggest trying to use a proper dome, and crossed over lower if at all possible. Off-axis performance on a 6.5" driver that does not have a "phase plug" above ~3K isn't "ideal" IMO. Just find a $5-10 dome and make a simple 1st over crossover for it cheap with crossover components.

As for box design you have a lot of flexibility and it depends on how big you want to go. The woofer characteristics along with the budget nature of the build has standard vented enclosure written all over it IMO.

1 cubic foot with a 4" diameter x 8" long port will result in a tuning frequency of ~55hz, ~1db of gain in the ~70-120hz range and an F3 of ~50hz. This can be done as a relatively largish bookshelf. I would not suggest going smaller than 1ft^3 with this driver as the bottom end will really get lost and the top of the bass range will get boomy.

1.5-2.5ft^3 in a floor standing design would fill out the bottom end very well with this woofer.

1.5ft^3 tuned to ~45hz (again about a 4"D x 8"L port) will give useful extension to ~40hz.

2.25ft^3 tuned to ~41hz (4"D x 6"L port) will give useful extension to ~35hz

I don't suggest going over 2.5ft^3. Things will just get weird.



Best of luck,
Eric

[Godzilla]

I've not simmed it but my gut tells me to seal this driver up in a smaller cabinet than 1cf and add a sub later. There's no frequency response chart so i cannot 'see' if a piezo will work well with it. I like piezo's regardless of their price.

Thanks for running the sims Eric!

[mdocod]

Hi Godzilla,

If there were definitely going to be a sub then I tend to agree that a small sealed box would make for a nice natural rolloff up high and a more composed sound. Not a bad idea if you don't need any extension from these. Vented is required to get any extension from these though.

Eric

[NcHalfrican]

Thanks for the responses and sim. Yeah, its a budget build...had some extra cash and wanted to build something Would this tweeter be more appropriate for my application? Size is really no problem. If I were to make a tall, floorstanding bass reflex for the focals, would quarterwave theory affect the response dramatically? I remember reading somewhere that with any "long" enclosure that it begins to work more as a quarterwave resonator as opposed to helmholtz resonator, is this true?
I don't plan on running it with a sub, at least not anytime soon.

[mdocod]

That tweeter would be much better IMO. Probably need ~12 ohm in series with it to match the woofer sensitivity. I would be tempted to look for something 8 Ohm with similar sensitivity so that I could minimize the use of resistance to match the drivers but that's more a personal approach thing I imagine.

As far as the box goes... Brace and dampen. My understanding is that when the box has adequate bracing and dampening, the shape is not very important. You'll see speakers made at all price points using all sorts of cabinet shapes.

Eric

[lawbadman]

Any updates on this project?
Im thinking of buying 2 pairs of these speakers.