Questions about driver positioning.

[Wagge]

The other day I got an idea for a three-way speaker. The inspiration comes from down-facing subs and the thought is for it to be a compact, good looking three-way speaker with, not overwhelming amounts of bass, plenty of bass. Perhaps used as frontspeakers in a multifunctionell home-cinema (some stereo music as well). I have done some sketching and the result is shown below.

http://img23.imageshack.us/img23/1843/hgtalare.png
Enclosure volume 8.7 l.

Because of my lack of experience in speaker-building I'm planning to use a pre assembled crossover and cheap drivers to not waist to much money if i **** up. I choose the following setup:

Crossover 3-Way 8 Ohm 800/5,000 Hz 100W
Crossover 3-Way 8 Ohm 800/5,000 Hz 100W 260-210

JAMO 20414 6-1/2" Treated Paper Cone Woofer
JAMO 20414 6-1/2" Treated Paper Cone Woofer 299-911
JAMO 20470 4-1/2" Sealed Back Midrange
JAMO 20470 4-1/2" Sealed Back Midrange 299-952
Nuance TW5-2LR 1/2" Mylar Tweeter
Nuance TW5-2LR 1/2" Mylar Tweeter 279-061

And now to my questions.
First, are the drivers even worth the money or have I gone to cheap?
Second, will the downfacing woofer make any different?
My main thought is that the speaker is going to stand on the legs at my tv bench alt. on a specialmade speaker stand.
Third what happens if I one day would like to wallmount the speaker? Will it be catastrophic for the sound? Or would it be almost the same sound as if I would have the woofer front facing in a more traditionell way?

Gratefull for every tip I get! Love this forum and I feel glad to finally be a part of it!

[Inductor]

You have it all wrong.
Your speaker has a nice design but that's all.

Crossover 3-Way 8 Ohm 800/5,000 Hz 100W

That crossover is rubbish if you use it in your design.

JAMO 20414 6-1/2" Treated Paper Cone Woofer

Your woofer has a kind of high Fs (80'sHz) not very good for bass, and only 2mm of Xmax. Those subs like to move hair.
I bet the woofer you chosen would give a rather good mid.

JAMO 20470 4-1/2" Sealed Back Midrange

Has a very high Fs at ~700Hz, when your xover is about 800, usually a good idea to have 1 octave. The same with your tweeter.

[sreten]

Hi,

The whole endeavour is a a disaster area waiting to happen ........

See the links below especially the first few.

rgds, sreten.

undefinition
(see if nothing else, the excellent FAQs)
The Speaker Building Bible - Techtalk Speaker Building, Audio, Video, and Electronics Customer Discussion Forum From Parts-Express.com
Zaph|Audio
FRD Consortium tools guide
http://web.archive.org/web/200909021...esigningXO.htm
RJB Audio Projects
http://web.archive.org/web/200909022...ve99/Spkrbldg/
Speaker Design Works
HTGuide Forum - A Guide to HTguide.com Completed Speaker Designs.
DIY Loudspeaker Projects Troels Gravesen
Humble Homemade Hifi
Quarter Wavelength Loudspeaker Design
The Frugal-Horns Site -- High Performance, Low Cost DIY Horn Designs
Linkwitz Lab - Loudspeaker Design
Music and Design

Great free SPICE Emulator : SPICE-Based Analog Simulation Program - TINA-TI - TI Tool Folder

[AllenB]

You would want to cross between the woofer and mid at a low frequency to make this work. It could be done if you know what to expect.

Originally Posted by Wagge

not overwhelming amounts of bass, plenty of bass.

It's not so much about how much bass, as making sure it all gets to you with minimal colouration.

[Cal Weldon]

Hi Wagge,

The words may be tough to take but both Inductor and sreten are correct. If you want a down firing woofer, you will have to cross it very low so don't have directionality problems. You will also want to power it with it's own amp. Something to consider might be a fairly rugged full range like a Tang Band, Mark Audio, CSS or others and add a helper tweeter crossed over really high. The XO will be much more forgiving and rather easy even for a beginner. I have done something similar in an all-in-one. I am currently using this in my kitchen and absolutely love it. The pictures were taken when I used foam to seal the top if you are wondering why it looks a little funny.

EDIT: AllenB posted while I was typing.

[Wagge]

Thanks för all the feedaback. This is great a learning experience and Inductor thanks for the comment on the design But to sum up everything, you think I should design my own crossover with a much lower xo for the woofer and a higher xo for the tweeter. You also think I should rethink som of my driver choice. I have some questions about that.

Q- Is there any advantage to have the mid sealed back and not depending so much on the enclosure since it already kind of small?

Q- And a question from the first post. What will happen if I do the changes you suggest and get a decent playing speaker but then decide I want to wall mount it. What will happen with the down-facing sub will it sound awful? Does the down-facing sub depend alot on the material beneath it and how close it is to the ground?

Sorry sreten i haven't had time to read through all your posts hope I don't ask a question you already answered. And thanks Cal Weldon always inspiring to see someone having similiar ideas and gotten them to work!

Q- Cal what drivers did you use in your speaker? And what kind of amp did you use for the sub in your build? How do you get it to work in crossover?

[Inductor]

First things first. More important things should be done before less important things. You should establish priorities here. What do you want the speakers for. Is it to be on the floor or to hang from walls. Very nice monitor speakers are done that way. Also very nice subs are on the floor like in your design but having the advantage of a very wide dispersion that would not work in other cases. If you want a speaker for both uses fine, but you should go with kind of a different design. Have you checked the 4th Order Bandpass as an option. Your mid/woofer with go lower in this case (~100Hz) as your original design should be (your first main error). That would be a good idea for the design of your low frequencies sub. You can use a simulation like (from Google)
Shavano Online - Sub Woofer; 4th Order Bandpass Calculator or other (in metric).

Now if I was you I would choose an established design, because you don't have the total knowhow. Here, a nice place to go
DIY Loudspeaker Projects Troels Gravesen

So, for all the options you have you are going to need to come up with the (your) decision of your main speaker driver and that will be ?????. Is very difficult (easy) to speculate in a future design you don't have the drivers for. (If) You want to build a good 3-Way or 2-Way. In the first case choose a good mid/woofer. Notice I said first, only then the sub (or woofer) and tweeter. In the second case, for a good 2-Way system choose a good mid/bass. Notice that they probably will be very similar, the first speaker (with sub/woofer) would give you more extension.

Note: In this case (my opinion just for you) better mids are not sealed back. As I said choose your main mid driver with the quality point in mind, smooth curve and low Fs, and go from there.

[Inductor]

Just an idea for a start. Nice kit.
Ciare KHZ03
Paire d'enceintes Ciare KHZ03 en kit
You can add the woofer in the same or another separate box, at the same time or at a later date. You can look for availability of parts/drivers in your area, if you don't want to buy the wood and all. Kits are good because they bring in the crossovers.
THIS IS THE Ciare HS160 - 23.94 euro
Haut-parleur de grave Ciare HS160
Ciare subwoofer KSW 02
http://www.ciare.com/pdf/catalogo/KSW02.pdf
KSW02
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