Sonolink Studio Project

[sonolink]

Thanks for your replies, gentlemen.

are the soffits larger than your cabinet? it looks like the speaker box is centered.

They are indeed. You can see it in the last sketchup file I attached a couple post earlier.
Here's a Top View:

StudioSonolinkF8.png

I think I already asked this several times, but you never noticed, and now you have already built the soffits without taking this into account

I did notice your comments regarding this, Stuart, but as I previously answered, the cabinet I built is a copy of John's "Speaker Unit" in this file: http://johnlsayers.com/Stuff/components.skp (speaker unit tab)

1) What is the purpose of the OUTER box, surrounding the INNER box into which your speaker fits? I do not see the acoustic purpose of that box. Please explain what it is supposed to accomplish.

I don't really know the acoustic purpose of the upper part of the cabinet, as I'm no expert (and John would be more indicated to answer this since it's his design), but I would guess that being a modular design, it's purpose is to contain rockwool, still to be added as I mention next to the photo: "top insulation, speaker and cabling to be added..."
If it's bad, I can always saw the upper part off.

2) You have not extended your soffit panel down below the speaker, and have instead installed absorbent material underneath it. What is the purpose of that? Yes, you said it was supposed to deal with reflections off the back of the console, but you never did show the geometry that you used to calculate where it belongs and in any case you seem to have misunderstood the purpose, and John's design.

As I said before I used John's Speaker Unit, and I followed his directions on how to use it (or so I think...):

here's another modular design for small rooms. Select all the component parts and group them. Then re-scale to suit your room.
http://johnlsayers.com/Stuff/components.skp

The speaker front can change for any speaker, providing the depth is OK for the speaker size. It basically extends the speaker baffle to the floor except it adds an absorbent front to allow for reflections off the rear of the gear and puter screens etc. The port allows for floor/wall bass buildup to have somewhere to go where it hopefully dissipates.

Please let me know your thoughts and impressions, gentlemen.
Thanks for your time and help
Sono

[gullfo]

looking at it, i don't think it would be an issue but worst case you could bring forward and extend the middle section (on each end) to make it symmetrical although having slight asymmetry should be fine and some might consider desirable...

[Soundman2020]

I did notice your comments regarding this, Stuart, but as I previously answered, the cabinet I built is a copy of John's "Speaker Unit" in this file: http://johnlsayers.com/Stuff/components.skp (speaker unit tab)

Actually, yours is NOT the same as John's!

John's design does NOT have that intermediate box inside it: Yours does.

Take a close look:

First, John's design:

john-box.jpg

As you can see in that design, there is no inner box: There is only the box that contains the speaker itself, and the shell for the entire module (which you do not have in your design) to which the entire from soffit panel is attached, at the edges. Your front soffit panel is not supported on the edges, the way John's is.

Here is your design:

sono-box-1.jpg

As you can see, the designs are different: You have the speaker box that contains the speaker itself, tightly. Then you have that mysterious "intermediate box" which does nothing useful that I can see (acoustically), and then you do NOT have the full enclosure that supports all of the edges of the front soffit panel. In your design, the edges of the soffit panel are not attached to anything: they are just out there, flapping about in the wind, so to speak. This is what I have been trying to show you: Your desing is not the same as John's design, and I can't see the acoustic reasons for doing it the way you did it.


- Stuart -

[PandPstudios]

I've been following this threat and have noted Stuart commenting that you should extend the soffit at the bottom so that the Speaker "sees" the same or almost same amount of soffit length (extended baffle) from every direction. But I certainly DID notice that in john's design the soffit only extends to the sides and above. Why is this? did he prefer to avoid the reflections coming from the desk and therefore cover this section with insulation?

[gullfo]

it looks like John's design simply wasn't scaled to the size needed based on the drawings.

if you look at John's baffle design, you'll see below the hard baffle plate is another plate indented to allow absorption to be put there. the absorption is used to reduce reflections off the desk, the indented plate extends the baffle down to 300mm (12in) off the floor.

[sonolink]

Stuart,
I think I understand it now: basically, what you call the "intermediate" box should be my drywall (inner leaf).
The bass trap covers all the soffit width and is a sealed box only open at floor level.
Everything is held by a wooden frame (not depicted)
All the cavity is filled with wool.
The inner trap walls are covered with wool and hangers placed inside.
Please tell me if now this is correct or if I have left something out

Soffit1.jpg

Soffit2.jpg

What shape/size should I build the hangers?
Are the resonators ok?

Cheers
Sono

[gullfo]

you're missing out on the entire corner which could be used for bass trapping. do you need to build this out as modular units? if not, then framing out the baffle and taking advantage of the corner would be a good idea. the attached isn't modular but you can see the corners are filled with wide band absorption. maybe a compromise is to build out the slat units (as deep as needed, not angled per se) and frame out the baffle to allow the corners to be used.

[sonolink]

Thanks for your reply, Glenn.
No, it doesn't need to be modular at all. Ok, so to make sure I understood all this properly:

1- I should build a wooden frame to hold the soffit wall.
2- I should place/fix/screw/whatever the tight fix box holding the speaker to the soffit wall.
3- I should fill the cavity between the soffit wall and the drywall with wool, filling all along the front wall, corner to corner.

If all this is correct, I have one question: should I build a bass trap below the speakers, a sealed chamber with hangers inside and a single opening (bass port) 30cm tall at floor level? If so, should it occupy the width of each soffit wall?

As soon as I get a confirmation that this is correct I'll begin building it. I really need to clear my head on this and make sure I know what I'm doing.
Thanks a lot to all of you for your time and for helping me out with this.
Cheers
Sono

[gullfo]

smaller hangers under or over the speaker and full length hangers on the side. under and around the speaker (leaving some air space for venting) fill with some rigid and pink insulation. it is theoretically impossible to have too much bass absorption...

the speaker box should be supported separate from the face plate. there should be a gap between the baffle plate and the speaker box and you use a soft caulk to seal it.

[sonolink]

Glenn,
thanks for your fast reply
A couple more questions if you don't mind:
1-why not fill everything with wool instead of hangers?
2-On the previous pic you posted (room_11x15x8.jpg) are the hangers sections (corners) sealed from the central part and the angled side walls, meaning air exchange with the control room is only through a bass port under the speaker and a hole at the top of the soffit? (btw, my speakers are active Yamaha HS80M, so they need venting anyway).
Thanks for the pic, sometimes an image is worth a thousand words
Cheers
Sono

EDIT: I just noticed that in "example soffit.jpg" the speaker box has an open back Is this meant to be like that or is it just the drawing? Cheers

[gullfo]

the opening under the baffle plate is the entry point. not shown in the drawing (besides the closed speaker box and except for the box vent and wiring opening) is lot's of insulation lining the space and in areas other than the space left to allow the speakers to vent, you can filled with insulation - keeping in mind air space is good so consider using a combination of rigid and pink insulation to maximize the absorption characteristics. note also that the speaker box could sit on a shelf (as John's design), cement blocks, cast concrete, etc etc. there are quite a few examples on this site showing the options.

[sonolink]

Glenn,
Thanks for the advice. One last thing please: is the corner section sealed from the slat walls and the central section?
Cheers
Sono

[Soundman2020]

is the corner section sealed from the slat walls

In order to work, the slat wall module itself MUST be sealed: No seal = doesn't work. So yes, that part has to be sealed.

- Stuart -

[sonolink]

I know the Slat wall itself needs to be sealed to work, Stuart. My question was oriented towards the bass trap depicted on the pic Glenn posted, as it seems an interesting variation on John's design. Seems like the lower trap in John's design, here is the whole corner and speaker space, right?
That's why I was asking if the corner bit needs to be sealed from the sides and central part, or in other words, should air exchange only be allowed through the bottom bass port and the top vent opening?
Cheers
Sono

[gullfo]

Glenn,
Thanks for the advice. One last thing please: is the corner section sealed from the slat walls and the central section?

as a general rule - maybe, it's not critical to seal (as is a slat resonator) since it might be part of a larger wave guide structure and so on to expand the space your bass travels through (such as overhead wide band absorbers) and eventually back into the room. in your case, i'd make a best effort to seal it off and the vent on top of the baffle plate should provide enough release.