AudioNirvana 12" 5.6 cabinet details

[tsiros]

Hello all

I am in the process of planning the cabinet construction for these audio nirvana 12" cast frame speakers. I am a complete and utter noob, the only time i have done anything remotely related to speaker DIY is when i took the silly two way yamaha satellite speakers and cut a hole in their back and inserted a toiletpaper center in there with hole diameter and tube length similar to those of similar speakers. ANYWAY.

I listen to all sorts of music, from full blown orchestra to chamber music... from Glass Hammer to All Shall Perish (i will save you the anguish of listening to an example. Imagine a diesel truck trying to start in a cold cold morning. I also play the electric and i am mostly a technical death metal player) and from a capella to... well... this ... or this... Anyway, again...

I am semi-decided to use the 5.6 cabinet, mostly because commonsense audio suggests it. If someone has a cabinet to suggest that is easy to build but doesn't sacrifice sound quality significantly, i am open to ideas.

I was planning to use plywood ~20mm, because i thought it would be more rigid than MDF, but a friend says that MDF has more uniform characteristics: its properties don't change as much as plywood does.

1. Do i want to use MDF or plywood? I am kinda cheap, BUT i also want it to sound decent.
2. Is 18mm thickness good? if i go 22mm would it be better?
3. Do i butt-joint it? do i glue it?
4. Does the speaker rim HAVE to be flush with the baffle? same friend says yeah or else the sound will suffer. But i see speakers from dynaudio (example) that don't seem to be flush I think making the 'step' in the front baffle will be a small challenge. I have no special tools... I have a dremel... and some duct tape though.

those are my main problems.

I want to paint it rather than lacquer it, because it is cheaper, i do not care AT ALL at the aesthetics of it (sorry if that sounds cheap to you. I want my amp's faceplate to look as pretty as possible, though... that counts for something, right?).

 

[4krow]

Heh Heh, I agree with a lot of what you say. I made quite a different cabinet for my AN speakers. They are the 8" cast, alnico magnet. Anyway, I tend to think that I like the plywood at 22mm better than the MDF. Gives some of it's own flavor I guess. Now, I don't really disagree with those that think the cabinet should not 'speak for itself', but you can dampen an unruly cabinet better than liven one up. Anyway, David Dicks, the founder of AN and I were talking once about this, and he said that regardless of speaker size, the experience can be maximized by nearfield listening, thereby lessening room acoustics,etc. As far as glue, I tend towards using polyurethane or at least Titebond III. This also helps seal the enclosure. Butt joints are fine, especially if your going to paint the cabinet, and don't care so much about the looks. Don't worry about the driver being flush with the cabinet, as that effect is minimal in the first place. More importantly would be speaker placement, room acoustics, etc. These drivers that you will be using are REALLY efficient, so what are you going to drive them with?

 

[tsiros]

lm4780

the reason is that i need something good enough but also simple to build NOT because i am bored or do not want to build something (i enjoy assembling things! from my tamiya nitro force, to a discrete 100W amp). The reason that i want something simple to build is that so i minimize the chance something will go wrong or that the end performance of the amp is affected by my building skills. It's far more certain that the end result will fall close to the specifications.

 

[planet10]

Keep in mind that it takes about 32mm of MDF to be as stiff as 18mm of good ply,

In a box this size, you have a lot of wall panel. It will need to be well braced to avoid the box panels becoming seconday radiators.

dave

 

[aptquark]

Ya..what Dave and 4krow said. You could use both MDF and ply to add diff res. frequencies into the mix. I did this with my 2.8 AN 8 inch boxes that I built for the cast frame 8's. I know that there are better options for the AN speaker boxes..but have yet to come across any (from these gurus here).

KALI TIXI MALAKA!

 

[tsiros]

I would very much appreciate it if you refrained from using such language.

 

[FullRangeMan]

Tsiros:
Hi, I would suggest these suggestions on this old topic about fullranges x cabinets.
Please Note the post #25 from ERIKB1971, very good tip to reduce inside resonances in a box.
http://www.diyaudio.com/forums/full-range/200763-how-treat-passively-peaky-fullrange-drivers.html
Good Luck and inform us from the obtained results please.

 

[tsiros]

i think those holes disperse the sound waves. something like that. not sure. don't know the correct english term, i'm a greek physicist

 

[FullRangeMan]

1. Do i want to use MDF or plywood? I am kinda cheap, BUT i also want it to sound decent.
2. Is 18mm thickness good? if i go 22mm would it be better?
3. Do i butt-joint it? do i glue it?
4. Does the speaker rim HAVE to be flush with the baffle? same friend says yeah or else the sound will suffer. But i see speakers from dynaudio (example) that don't seem to be flush I think making the 'step' in the front baffle will be a small challenge. I have no special tools... I have a dremel... and some duct tape though.

those are my main problems.

I want to paint it rather than lacquer it, because it is cheaper, i do not care AT ALL at the aesthetics of it (sorry if that sounds cheap to you. I want my amp's faceplate to look as pretty as possible, though... that counts for something, right?).

Questions:
1) Baltic Birch plywood is beter sound, But MDF 30mm could be more durable and strong to a baffle.

2) For a biig fullrange baffle I could use MDF 30mm or BB plywood also 30mm(not 20mm), and other sides plywood 20mm.

3) If possible do both butt-joint and glue, as FR made inside resonances in all the audible range.

4) I do not like flush mounting, it is a precision work, takes time and benefit are very low. I prefer instead to cover the outside baffle with 5 or 10mm black felt layer to the FR alloy frame and the wood baffle does not make contact with each other.

Some DYNaudio speakers use suspended, float mounting baffles;
If good looking not important you would coat/overlay the entire outside of the box with black felt 5mm, which reduces a little more resonances in the room and costs much less than prepare/sanding, paint and polish.
Regards

 

[FullRangeMan]

i think those holes disperse the sound waves. something like that. not sure. don't know the correct english term, i'm a greek physicist

Yes, the assimetric holes reduce internal ressonances which may disturb the paper cone.

 

[tsiros]

Ok i need some advice on the order with which i will construct the cabinets:

1. get the wood panels cut, 22mm plywood
2. acquire strong glue for plywood, 2mm drill for wood and appropriate screws
3. match left and back panel, drill holes. apply glue, stick together, screw the screws. use damp cloth to remove excess glue
4. match right and back panel, drill holes, apply glue, screw the screws, use cloth to remove excess glue
5. match bottom and back etc
6. match bottom and top, etc
7. match middle bracing, glue and screw in place.
8. staple dampening material (what material i don't know) on top HALF above the bracing: top, left, right and back
9. match baffle, drill, glue, screw.
10. drill holes for speaker on baffle, using the driver in place, as a guide
11. since cab is complete, spray paint it (does acrylic spray paint work well?). watch it dry.
12. connect cables on driver, with appropriate length to reach the back connectors
13. somehow fit the driver in place ... since i can't screw it, i need to use and need to be able to access both the front and rear of the baffle, how will i do this?

 

[tsiros]

step 8b: mount these T nut things on the back of the baffle, to prepare screwing the driver

step 13: fit the driver in place ... screws go into the T nut things from the front

 

[FullRangeMan]

Sorry, I fail to understand your post #11 & 12, as seems your plan are built only two speakers, a detailed production plan is important only if you will do a serial large production for various workers.
As I see it, if you do a task today or tomorrow the result will be the same.
Regards

 

[tsiros]

I mean, are the steps correct? Did i forget something? should i pay attention to some particular step, do it in a specific way? For example: what screws should i use? perhaps i should not use screws?

 

[FullRangeMan]

I will no tell about the step flux, but I prefer screws for wood, which had thick thread/flange.
But I already see many DIYers using bolts with thing flange, as this Yamamoto YS500 OB test:
http://www.6moons.com/audioreviews/yamamoto9/wooferbar.jpg

6moons audio reviews: Yamamoto SoundCraft YS-500
I would not used glue to fix the driver on the baffle, as it is permanent.

 

[tsiros]

of course no glue for the driver! i was talking about the speaker panels...

nice woofer bar

 

[FullRangeMan]

Bolts for the panels are used only for the back side, in case the speaker are for listening tests(to easily replace the inside stuff foam or parts), otherwise a good glue must be used.

 

[jimbro]

Don't really like t-nuts though some do. You can put a small screw in the back to hold them in place. If you're planning on recessing the driver I definitely would not use them because the baffle would be too weak. Best to just use wood screws for the driver. If possible, I would make the back removable and once you get your stuffing sorted out then glue it in place. Have a look at the construction forum for more tips.

 

[GM]

I've not have the various problems with t-nut as many have, but threaded inserts can't be beat AFAIK when there's little room for hardware: Thread Inserts for Wood by E-Z LOK

GM

 

[4krow]

T-nuts and threaded inserts have one thing in common, they bot should be mounted square with the panel. If they are even slightly tipped one way off axis, it's no fun trying to get a bolt thread to line up with them. I still think that they are superior to wood screws for mounting drivers though.