building boxes for speakers

[rlogjk]

This might be to advanced for me to design in Illustrator in order to cut it in a laser machine using 4mm plywood.
How much this bass reflex is important? Assuming I'm not looking necessarily for a high end sound

 

[Galu]

You said at the outset that the sound quality was a consideration.

Your design in post #14 is likely to give satisfactory results.

 

[rlogjk]

what about this idea?

 

[rlogjk]

Looking at the speaker dimension - what should be the hole size for mounting it? 72.5x72.5mm?

Edit:
Is my latest dimension make sense?
The depth should be bigger assuming 47mm depth of speaker?

 

[Galu]

The volume of your sealed enclosure design is around 7 litres or 0.25 cu ft.

That should be satisfactory. Obviously you must tweak the dimensions of the box to match the dimensions of the driver - so maybe a touch deeper.

The mounting hole size is indicated on the driver diagram as 72.5 mm. The circle diameter for the screws to front mount the driver is indicated as 83 mm.

P.S. I presume you to be quoting internal dimensions.

 

[rlogjk]

I have changed the depth to be 70mm. I'm still wondering regarding the length. If 138mm is too short?

 

[Galu]

If the depth is increased, then the height should be decreased to a figure that keeps the internal volume at 7 litres.

Volume of rectangular box = height x width x depth

My calculator suggest the new height should be 105 mm.

 

[rlogjk]

If the depth is increased, then the height should be decreased to a figure that keeps the internal volume at 7 litres.

Volume of rectangular box = height x width x depth

My calculator suggest the new height should be 105 mm.

So when ever I change one of the parameters (height width depth) I should make sure that the Volume is at 7 litres?

 

[Galu]

The problem is how to attach it to the box, since it has a non-existent frame. Probably it's meant to be mounted from the back

Stop press! Looking at the driver photograph , I agree with pico that rear mounting of the driver would be necessary.

This means that the back panel of the box must be removeable so that you can mount the driver on the rear of the front speaker board or baffle.

It's not clear what the diameter of the opening should be, so I'll have a further look at that.

The alternative is to choose a driver that is capable of being front mounted on the baffle.

 

[rlogjk]

Regarding the mounting of the driver. Because I'm printing all box parts I could connect the driver from "the back" and only after glue the box so that should not be so much of a problem, right?

regarding the 7 liters volume of box. Why this particular volume?

 

[Galu]

Here is a photo (courtesy of member hm) showing the driver rear mounted.

connect the driver from "the back" and only after glue the box

That's OK.

regarding the 7 liters volume of box. Why this particular volume?

Because that's the volume you chose to use in post #14 and it seems reasonable to me. I don't know what the optimum sealed volume is for this driver.

EDIT: Regarding the cut-out diameter for rear mounting see next post.

 

[Galu]

Visaton recomends 75 mm diameter, in which case the circular (annular) gasket would sit inside the mounting hole.

It would need to be a snug fit to avoid air leaks.

 

[Richard Ellis]

"...I don't know the optimum sealed volume for this driver." Gotcha"...sealed for a Qtc of 0.71 response, One liter of volume. Because the efficiency bandwidth product is steeply oriented towards that of a vented larger box, there is no bass performance at all...the "bottom-end" rolling away at minus 3.04 decibels at 179.77 hertz.

--------------------------------------------------------------------------------------------------------------------------------------------------------Rick...

 

[Galu]

Thanks Richard.

I don't think the OP has made it clear whether these gallery speakers are intended to project music or speech.

If the latter, a 1 litre sealed enclosure may be adequate for the job.

 

[rlogjk]

I don't think the OP has made it clear whether these gallery speakers are intended to project music or speech.

music. Mainly female singing specific musical note

Edit: regarding the screws needed for mounting the driver is it should be 4M or 5M is not so obvious (at least for me) from the Datasheet

 

[Galu]

The lowest female voice frequency is 165 Hz, so you might just get away with a 1 litre sealed enclosure.

Richard's earlier bass reflex design would obviously be the better option.

 

[rlogjk]

The lowest female voice frequency is 165 Hz, so you might just get away with a 1 litre sealed enclosure.

1 litre is very small isn't it?

using this calculator and entering my previous dimensions of 105 75 90 the calculator show volume of 0.7~ and not 7~

 

[Galu]

Correct, I got my decimal point in the wrong place!

Blame the Christmas cheer.

 

[abstract]

1 litre sealed sounds about right. I wouldn't trust extended bass response where the xmax is 0.25mm and the VAS is 1 litre. Box joints should be nice and strong, but if the volume is too big, the design may require additional bracing, which seems like overkill.

 

[Galu]

regarding the screws needed for mounting the driver

The diameter of the head of the screw must exceed 4.5 mm.