Need Help Urgent

[beefa]

Hello all

My name is Curtis. Im in year 9 and for D & T were doing speakers. Ive got myn picked out and all the information, but my dt teacher is not giving me the help i need. I have all the info, thanks to www.jaycar.com.au, and i just need a little more to get me off.

Nominal impedance: 4 Ohms
Power Handling: 125 Watts rms
Sensitivity - SPL - 1Watt @ 1 metre: 88.17
Voice Coil Resistance (Re): 3.5 Ohms
Resonant Frequency (Fs): 33.298Hz
Mechanical Q Factor (Qms): 8.193
Electrical Q Factor (Qes): 0.534
Total Q Factor (Qts): 0.502
Equivalent Volume (Vas): 29.55 Litres
Cone Area: 0.0346 Square metres.
Voice Coil Diameter: 50mm
Xmax: 9mm
Speaker dimensions: A 255, B 245, C 233



Typical application
Vented box:
Box volume (litres) 48lt
Tuning Freq (Hz) 26.54Hz
-3dB point (Hz) 25.15Hz
Cabinet dimensions (internal)
591(H) x 365(W) x 226(D)mm
Port size 66mm dia, 270mm long



What dimensions do i need to order for my wood? Im getting it professionally cut, and i was told to leave 1 mm or so? And the thickness of the wood is also unknown to me. If any information could be forwarded, it would be appreciated.

I also know that i may have missed anything, so if u pick up anything i need to know, please, tell me :)

Thankyou for your time,

Curtis

[ozwinner]

Run for your life Beefa, the spelling Nazis are coming, RUN Beefa, RUN

Sorry I cant help with your question.

Al :D

[beefa]

whats wrong with my spelling?

[ozwinner]

As far as Im concerned, nothing!

But other people here have this thing for pulling people up for their spelling.
So you better RUN.....................
Im not having a go at you Beefa. :)

Cheers, Al

[GeoffW]

Appears the spelling Nazis may have been flamed into silence, or maybe they have gone to a spelling board. :eek:

Sorry Beefa, can't help with your question either - all that talk about frequencies and factors is far too testical for me. :o :o

Geoff :D

[silkwood]

Dear Mr. Curtis Beefa, I also know close to bugger-all about resonance, impedance etc. However I do know something about buying magazines, and, coincidentally, Fine WoodWorking Dec. 2002 edition has an article on building an entertainment centre. The chappie who wrote it does appear to know what he's talking about. He suggests speaker boxes could best be built from 1/2 inch (okay he's a yank) MDF with 1/8 hardboard laminated either side.

Hope this helps. If you want further info from this atricle you should find it at your local TAFE which specialises in woodcrafts.

PS: Ozwinner, you win tonight's prize for making wine come out of my nose from laughing too hard! :D

Cheers,

[gatiep]

Curtis

First off: If you put your location in your profile, members of this forum may be able to give you help as where to go to get the right advice or materials. Australia is a large place tho.

I would use 18 mm MDF with veneer, which makes it 19 mm thick. Then you should use 45Deg joints so as not to have the MDF showing. This means that you have to allow 2 x 19 mm to the width, height and depth. Have you got the use of a tilting arbor table saw...if not it is not worth the trouble to calculate the dimensions.

The size to cut the MDF depends on the amount you have to allow for the joint type. Have you got a plan of how you want to construct the box?


If you get your MDF from a specialist supply shop you can give the inside dimensions that you have to them and their machinist will cut the mdf to the correct size including the 45 deg chamfer all round. Ask him nicely and he may even glue it up for you. Then like hundreds of other D&T students, your part of the D&T is to fit the speakers and finish the verneer. If you use unverneered MDF, you just need to paint it.



Gee D&T has come a long way since it was called "Woodwork" and the students actually did the work themselves overseen by the "Woodwork Teacher".

[hcbph]

If the person machining your material can make miter-lock-corners, I'ld suggest you have the corners prepared this way. You can get them for either a shaper or to use in a router table.

For an image, check out http://www.grizzly.com/products/item.cfm?itemnumber=C2125 to see what a cutter looks like.

They make holding miter corners while gluing much easier if done properly.

Good luck on your speakers.

[KevM]

Soundman, come on down, but in his absence I'll have a go.

Beefa,
You have provided the internal dimensions for the box,
Cabinet dimensions (internal)
591(H) x 365(W) x 226(D)mm
Port size 66mm dia, 270mm long

Use these to draw up your design, determine how you are going to make your joints, determine whether you are using pre veneered board, veneering afterwards or painting, ring an mdf supplier and get dimensions of the board you intend to use. Complete your design.

Surely Beefa, part of design & technology(I'm guessing that that is what D&T stands for) is to actually be able to draw up what you intend to build.

My 2cents worth, I'll get off my soap box now.

regards

Kev M

[fxst]

apparently its all too hard to study or use the resouces supplied by a school nowdays. Instant answers is what they want now not study and learn.....you supply the answers and he puts it into his paper and there ya go instant A
Peter :mad:

[Sturdee]

Instant answers is what they want now not study and learn.....you supply the answers and he puts it into his paper and there ya go instant A



Peter, we went through this a little while back with TheFool who also wanted us to do his work.

At least Beefa's spelling is a lot better than his was :D :D as so far only Ozwinner picked on his spelling. :)

Maybe we are now on a mailing list for doing everybody's schoolwork :eek:

Peter.

[ozwinner]

Now come on Peter!!!!!!!!!!!!!!!!!!!!

Im NOT the spelling Nazi. :eek:
There are enough of them already without me joining in.
I was just warning the poor kid before it was too late.............

Al :p

[eddie the eagle]

Kev M's picked it up guys.

The 'design' part of D&T is that you should be able to figure out how/what sizes you need to cut given dimensions. (hint - draw this out on a piece of butcher's paper and all will become obvious)

The research part is done in part as beefa's found some of the info he's been asked to find (well . . . almost . . . what material are you going to use, and how thick is it? - you'll need thickness to determine the lengths to which you'll need to cut the timber. Depth of the cabinet (=width of timber) is also in your specs that you've cut & pasted off the Jaycar site).

The 'technology' part of D&T includes the making part


If you can't figure it out Curtis, try going to your teacher and explaining exactly what you have done and then what you can't figure out, not a general: "I don't know". Just a guess on my part as to what you said.

Teachers will generally help those that have a go, instead of those that sit around and expect things to be given to them. Sounds as though you could be one of the ones that's had a go to date but have hit a snag.

(By the way, the D&T syllabus that the teacher is working to requires you to do the research and the working out, with the teacher there to help/guide you to solutions and ways around problems. eg: you're meant to be learning how to solve problems. I'd hazard a guess that the teacher's doing what's required - I'm a D&T teacher now, as well as a cabinetmaker)


Just a wild guess - is this urgent because it's due Monday?

Cheers,

eddie

[Bob Willson]

Ozwinner

Im NOT the spelling Nazi.

Sorry, too late by far.

Ozwinner's a spelling Nazi, ozwinner's a spelling Nazi. :D :D :D :D

[ozwinner]

I waz warning him before yuz got to him,,,,,,,,,,,,,,,,,,,,,,,

See, I dont care if their speld rong.

Al http://instagiber.net/smiliesdotcom/otn/violent/ketten.gif

[Sturdee]

Now come on Peter!!!!!!!!!!!!!!!!!!!!

Im NOT the spelling Nazi. :eek:
There are enough of them already without me joining in.
I was just warning the poor kid before it was too late.............

Al :p

So sorry :o Al, I accept that you are not a spelling nazi. But in warning Beefa you raised some doubts. :p

Peter.

[Sturdee]

Ozwinner
Ozwinners a spelling Nazi, ozwinners a spelling Nazi. :D :D :D :D


Dear honourable spelling Nazi,

Don't you mean "Ozwinner is a spelling Nazi " :p


Peter.

[ozwinner]

Thats ok Peter, its just that the spelling Nazis realy me, and to be lumped in with them.......well you know. :(


Cheers, Al http://instagiber.net/smiliesdotcom/otn/animals/imubashing.gif

[popawisky]

D&t???? Is that like the DT's????

Used to get that years ago fron too much booze.

[eddie the eagle]

D&t???? Is that like the DT's????

Used to get that years ago fron too much booze.

D&T = Design & Technology, but it has been known to drive you to drink.

Have a good one.

eddie

[Bob Willson]

Dear honourable spelling Nazi,

Don't you mean "Ozwinner is a spelling Nazi " :p


Peter.

Yes I do. :) Or rather, as it now reads, Ozwinner's a spelling Nazi

[kenmil]

whats wrong with my spelling?

Let us start with "im" - I presume you meant "I am" ?
&
then there was "ive" - did you mean "I have" ?
&
followed by "were" which I think you meant to be "we are"
&
my personal favourite, "myn" - you no doubt meant "mine"
&
then there was "u" - which I take it to mean "you"
&
to be really picky, "thank you" is two words, not one.

That is on the first reading, and I found it too distressing to give it a second.

Sieg Heil !
Spelling Nazi. ;)

[Caliban]

All
As one who has the very deep psychological scars incurred in the honourable pursuit of raising the spelling standards on this otherwise exceptional BB, I feel that it is an insult to have Ozwinner included in our rapidly diminishing number. (No offense Ozzy, but you need to earn your stripes, although your smart **** comments show potential :D ) I don't know where to put Sturdee, he tends to agree with us until he thinks it is funny to put excrement on one of us-usually a good enough reason to be one of us ;)
Now it seems to be only Kenmill, Bob Wilson and me :eek: )
when the going gets tough the tough melt into cyberspace. :confused:
Stand up and be counted you big girls :cool:
Cheers
Jim recently un retired spelling Nazi :D :D :D

[Sturdee]

Jim, in another post I said:

......... that the spelling issue has got out of control. What used to be a friendly dig has taken on a life of its own and is becoming way too serious .....

and

......I have always been wary about the fine line between someone being discouraged from posting and having a good natured dig. From now on I feel that the spelling issue is dead, and I will not post on it anymore...........


I sincerely feel that way so I will no longer comment on any spelling issue. Enough is enough. :( :( :(


Peter.

[Caliban]

Peter
Now you're making me feel guilty. I've never had anything other than a good natured dig at anyone. However, it seems that the Aussie ability to laugh at ourselves has sadly disappeared. So from now on I too will not post any comments about spelling or punctuation, even if it is really asking for comment. Instead I might put spelling hints or punctuation tips as my signature and see if it is taken as being helpful or smart alec. (Have you noticed that has been made obsolete by the automatic rude word editor, so when I write a word like **** it is changed like this. :) )It helps me be nice.
cheers
Jim ;)

[beefa]

ok. the kind of feedback im getting from you guys is that you think i should do all work by myself. thats from some. But i think that everyone is getting off topic with the spelling.

Anyway, i've managed to pick out some, some!, reasonable information. Thanks to the guys with info, and the guys who said they didnt. But people baggin me out, no thanks. Not needed.

Ive managed to understand that i need 19mm MDF and that i just add this to my original dimensions.

To those who were asking questions, Im getting my wood from Mitre 10 and getting it cut there as well. As im in year 9, nobody cares what kind of joins we have. Im just gonna get a butt-joint. (not in that way :) )

Any questions, dont mind to ask. By the way, my spelling is perfect, or close to, :cool: , BUT, my grammar isnt the best :D

SEEYA
BEEF

[Zed]

you tell 'em beef! communicaiotn is more important than the speling...

I dont know too much about the acoustics (thats a whole different bag) but I understand that heavy/dense is best - it propogates the sound more efficiently (By this I think they mean that dense timbers should be used - hence MDF) If you being a young bloke are gunna listen to doof doof music I might suggest that you use a thicker dimension of MDF than 19mm.
I wouldnt worry about laminates and all that stuff unless you are going to put it in your lounge room.
the boys are right you need to draw a good plan and construct a solid box your self not just copy and paste thier words.

I remember that good heavy speakers always allow for vents so dont forget to build them in too.

I feel sorry for your mum - may I suggest frank zappa as an alternative to doof doof ?

Cheers Zed - wating to be flamed or corrected. :D

[Caliban]

Zed
I (now that I've reformed) tend to agree that communication (no matter how you spell it) is more important than spelling. When I finally work out what people are trying to say I find that I enjoy their posts, especially when they suggest Frank Zappa as an alternative to doof doof. However, if my mum had ever heard the words to Frank's songs that I used to listen to I doubt I would have lived to pick on anyone's spelling. :D :D :D
I also hate small, yappy dogs.
Does anyone still put insulation batts in speakers? Seems to me you could use thinner mdf if you put some pink batts in there. Or does that deaden the quality of the doof doof? :confused:

[kathy]

Bloody hell you guys, this is better than tellyany day. :rolleyes:

See Ya
The Blonde

[soundman]

Back to the problem at hand

almost any board product will produce a reasonable speaker unless you are some golden eared freak.

mdf. ply, chip. all fine for a school boy project.

anything thicker than 15mm will be ok at the power you are talking about.

but joints will be fine for your first few attempts at speaker construction.
make sure you glue & screw the joints well. & that the fit is good and airtight.

as for size
If you ahve already established your internal dimensions

draw a cube (irregular) representing the interior surface.
draw boards for the front & back the same size of the front & back of the cube & ## thick.
draw the top & bottom flush with the back of the back board you have just drawn and extend 30 to 40mm past the front of the front board you have just drawn. and flush with the edges of the interior cube.
draw the sides flush with the extents of the top & bottom you have just drawn.
the top & bottom but to the front & back. the sides but onto the sides.
the most important dimension to get consistent is the width of the top,bott, & sides & to flush them up spot on at assembly.
the front overlaps & is thus less critical
the other joints can be flushed up with a belt sander. tend to overlap them a fracrion of a mm

post again if you have problems.

[Caliban]

why is the girl allowed to swear? :D
cheers
Jim

[kathy]

Am i rite in asuming u r refering to moi in regardz 2 tha swerring hobo*
pleaz acept mi moast humbile apoligyz if i afendid u.

The Blonde

[beefa]

soundman, wonderful, beautiful, boost of information :D :D :D thankyou so much.

this information is what i was looking for. noot bluddy speilling (muhahahaha :eek: )

thankyou so much for the info again. 20mm is the size im using now. teach says that i need to leave round an extra 2mm or so, this right?

thanks again,
beefa

[eddie the eagle]

soundman, wonderful, beautiful, boost of information :D :D :D thankyou so much.

this information is what i was looking for. noot bluddy speilling (muhahahaha :eek: )

thankyou so much for the info again. 20mm is the size im using now. teach says that i need to leave round an extra 2mm or so, this right?

thanks again,
beefa

Sounds as though you're further down the track now, Curtis, than your original position - [which I read as: "I have internal dimensions, I don't know what I'm going to use, my teacher's useless, tell me the final sizes that I need to cut, even though I don't know how thick the board is]

If it's a full butt joint and the top & bottom go full width (ie: MDF end grain from the top/bottom panels are visible at the sides of the carcase) then you cut the side to the same height as the internal dimension and the top/bottom at the internal height plus (2 x 20mm) = 40mm.


Do you know why the teacher wants an extra 2mm all round? if it's allowance for cleaning up damage in transit then OK, or is it allowance for error in glueup/measurement - better to be a fraction over than a fraction under, especially if the inside dimensions are critical.

Is the joint butt or butt/nailed or butt/biscuit?

If you're getting it professionally cut and handle the cut boards carefully, you may get away from needing the 2mm allowance, providing that you can align
your joints accurately.

To keep it square if you're only gluing up the carcase without a front and back, nail a false back temporarily onto the thing to hold it square as the glue dries.

As I said, why did the teacher say to include this 2mm allowance - did s/he call it trimming allowance or the like?

Cheers,

eddie

[Caliban]

Kathy
You did not offend me .
It's an old gripe I have with who edits any rude post I make, but lets others go unedited. Nothing personal, it's just a matter of equity. :D

[kathy]

No worries Hovo, just joking. :)

See Ya
The Blonde