First Project - Wife Pleasers

[jefe_de_estado]

I've been wanting to build my own speakers for quite some time now and have spent a fair amount of time digging through this website and several others. I finally have all the wood working tools that I need to build a set, now I just have to finalize my design and scare up a few dollars to pay for it all. I would like to toss my design out there and please critique.

Goals, Objectives, & Req's:
-Wife pleasing SMALL speakers
-Must perform as good or better than my Bose 201's (must be much smaller also)
-Main use as Home Theater Speakers
-I have a decent sub, so they are not required to produce huge amounts of bass
-Inexpensive ($50-$100 each)
-Room Size: roughly 20' x 15' x 10'ceiling
-did I mention the need to be small?

Design:
2-Way
Woofer: Peerless 830856
Tweet: Tang-Band 28-847SD
x-ed somewhere in the neighborhood of 2kHz

Unibox tells me that I can do a 2.2L vented box with fb=85Hz, but that requires a 1.5"dia x 6.25" port. So I decided to orient the port vertically (don't know if that is good or bad). This gives box dimensions of 3.75"x9"x4.5" (think I just saw a problem there... comments?)

Just to get an idea of the size and layout, I modeled it up: (see pic), I'm sure the final construction design will change before I build it.

Since the box is so small, the x-over will probably have to be outside the box somewheres

How am I doing so far? Any thoughts or comments would be greatly appreciated!!!

[Iain McNeill]

Firstly, welcome to the forum!

A couple of details to check:
The port tube subtracts volume from the enclosure so you need to add it to the simulated volume. or at least check that your design software accounted for it.

You can put angles in the pipe. Use a length down the center of the path as the length. Don't forget end effects that add 5-10% of length.

Also, consider the phase/delay of putting the port opening behind the acoustic center of the other drivers. Check your S/W accounts for that too.

I'm sure others will chime in too


BTW: nice drawing! what software did you use to draft it.

[planet10]

With the box sides that tight to the driver, you will get coloration (usually a honkiness) from relections back thru the cone.

dave

[Shaun]

Having the port exit at the bottom presents a problem in that there ought to be clearance around the port (both internally and externally), else the proximity effects add onto the port's effective length. You might consider putting the port at the back, and making it a smaller diameter, which will require a shorter length. The down side of using a smaller diameter port is that it will produce chuffing: argument no.1 for putting it at the back; no.2 is that there will be mid frequencies coming through the port. Not much you can do about the latter except to locate the port behind the tweeter, as opposed to behind the mid/bass driver. The chuffing can be reduced by using a flared port. This will require the total length of the port to be a bit longer than the calculated length.

[col]

you might want to spend an evening with the wife, cook her a meal, bottle of expensive wine etc... and see if you can get in her good books then drop the question "do you mind if I make the speaker cabinets 10 litres?"

col.

[Shaun]

Hehe. Wise words.

[Magura]

Originally posted by Shaun
Hehe. Wise words.

Yeah, it's just the wrong way of getting in her good books


Magura

[Geek]

Wife Pleasers

They don't exist

If you're lucky, she'll get used to them and you can buld the next a wee bigger and so on until you have floorstanders

(we've worked out a system here @ diyAudio)


Cheers!


P.S. - looking really good so far.

[bjorno]

..Any thoughts or comments would be greatly appreciated!!!..

Hi,

I wouldn't recommend to design a BR box if you have a sub that can be XO:ed at about 100 Hz and have a 2nd order LP LR slope for SQ reasons.
A closed box with a volume between 2-3 L should work well using the natural roll off at the - 6 dB point (at 90-100Hz) when summed with the woofer.

b

1(1)

[jefe_de_estado]

hahahahah!!! Nice responses... I think I like the idea of starting small and working my way up to this:
http://www.diyaudio.com/forums/showt...48#post1569248

Too bad I read some of those posts to her... now she's on to me!

Iain, I used Solidworks to draw that up. If I had more time I would have assigned everything the right material and made a photorealistic image, but since its all going to be black it makes it a bit difficult to work with as you can't see lines and edges. I use it quite a bit for work but this is way more fun than work.

Planet10, is there a general rule or guide as to how wide the box should be?

Shaun, I guess I should explain the idea behind the down firing port. I have a 1 year old that will be walking soon, accessible ports will soon be Cheerio collectors... :-) I guess i could cover the ports with the wire mesh that people use to keep squirrels out of the attic. Would more than 1 smaller port avoid the chuffing issue? The port in the drawing has one flared end, but you can't see it in that view

bjorno, I'll have to check my sub, but I'm pretty sure I could x-over at 100hz, which would get rid of port issues all together if I went sealed. Where did you get that Mathcad worksheet? That looks great!

Thanks for all the advice... Keep it coming!