Speaker Help

[dustruss]

Hello, I am having problems with the speaker I tried to make. It is a 3-way speaker. The speakers I am using are the Dayton 15" series II
http://www.parts-express.com/pe/show...number=295-130
, Alesis 5 1/4 woofer for the mid
http://www.parts-express.com/pe/show...number=299-160
, and selenium tweeter
http://www.parts-express.com/pe/show...umber=264-360.
I used a 2nd order crossover with low pass at 600 HZ and high pass at 4800 HZ.
I hooked everything up and my tweeter was very loud so I put a resistor across and in series with it sounded a little better.
The speaker still didnt sound that well the 15 inch woofer got distorted at too low of a level. I think it might be because the low pass should be set lower than 600 HZ. I was wondering if anyone had any ideas on what I should do or tell me what I am doing wrong. Maybe these speakers are not a good match I dont know.

Dustin

[Moondog55]

I just had a look at the performance graph at PE, and I would be crossing that woofer about 200Hz, no higher than 300. I didn't see any graphs for the mid or tweeter you chose so I can only offer a "generic" opinion.
Perhaps you should post some more information; such as box size type and constuction, along with a diagram of the XO with the values you used showing. and whether or not the box has any stuffing or damping material inside it.
Regards and welcome
XO for a 5.25" mid should probably be quite a bit lower at around 2700/3200

Regards
Ted

[dustruss]

The volume of the box is 6688 inches cubed or 3.87 ft cubed. I planned on having it vented but I havent made the hole yet and I havent really thought about damping yet but I know I need it. To be honest I used the calculator on Lalana.com for my crossover. But I would like to learn how to do all the callculations on my own. Do you know of any good sources for me to learn from.

Thank you
Dustin

[mjf]

volume of the box?when it is too big or too small the bass will not perform well.
or there is something wrong with your xo-design.
regards..........

[musgofasa]

Have to agree with Moondog55 on the crossover points. WAY too high on the 15. I would say start with 200 hz if going passive. 12db per octave or more. If you could post a diagram of what you built, we might could start there.

The enclosure size is a bit large for sealed. (if that is internal), but I am wondering if all three drivers are in the same space? If you have a cabinet within the cabinet for the mid and tweet, that would be better. Still that much air will need the port. According to PE, a 3.5 in port 10.8 inches long is about right. I haven't simmed the driver, but I am betting that won't be far off.

Other than the 15 sounding distorted too early, how do the mid and tweet sound? The xo could probably stand to be lower for the mid, but that might depend on the characteristics. There are people here with a lot more experience than me on that one. With this set up, you will run into all sorts of issues with the crossover. Not a bad selection of drivers. I don't know how well they will interact in the same box, but I can certainly think of ways I would use them.

Take care,
Robert

[Moondog55]

Just ran some numbers in a box program.
Transient perfect box if you add some polyfill and/or fibreglass to control standing waves inside the box, the box itself is a little small for vented according to Jeff Bagbys box calculator.

That box Fc = 37Hz, F6 = 20.25Hz.
75 watts will give about 109dB at about 100Hz and a shallow roll-off after that.

More than 90 watts in a box that big and X-max plus 20% so the box can be smaller ( if the mid is in its own smaller internal box. Have you deducted that volume from the internal volume you gave us??

[Moondog55]

Try this link for JBs programs

http://audio.claub.net/software/jbagby.html

[dustruss]

I attached a photo of the schematic I used. I added some resistors for the tweeter values were 5 ohm parallel and 20 ohm in series.

The mid is not in its own internal box. The volume I gave you was of the entire box. If I put it in it own internal box it will it improve the speakers overall performance.

The Midwoofer right now sounds really good the tweeter sounds ok.

Thank you for all of the help you are giving me

Dustin

[Moondog55]

Definitely needs a seperate section/box but only a couple of litres or so, sealed and fully stuffed; I think you need to rethink your box.
I have retrofitted small mids with a sealed section using largish steel coffee cans glued in with epoxy if reworking the box isn't an option.
If you have the mid sharing the same box the back pressure from the woofer makes the mid move in time with the woofers motion, really muddies up the sound, and worse.

Loosing a few litres to a small container for the mid will allow the woofer to handle a little more power and give you a better F3.

[dustruss]

What if I made the mid and the tweeter enclosures a little larger, large enough that I do not have to vent the main box. Or would that be a bad idea? I can really use steel coffee cans as enclosures?