English help with a Boxsim project?

[brkl]

Hi! I've been designing a speaker with Boxsim and I need someone who knows more about loudspeaker to look at the project and check out what problems it might have. I figured this is the best place to ask, except I don't speak German! I haven't designed a speaker before and I don't really know all that much about all the different mistakes I can make.

The project is to make 3-way loudspeakers out of two cabinets of an old desk. I don't have the actual desktop, only cabinets. They look nice, so I think the best way to make use of the cabinets is to turn them into loudspeakers!

I chose the drivers and made the crossover (I know very little about crossovers) in order to straighten out the frequency response. However, I don't know if I caused some other problems. If anyone could take a look at the project file and offer some comments (in English), they would be much appreciated!

[walwal]

Welcome.

Your crossover is ok, but this one should work a little better. Not so harsh anl less Resonances from the Sc 10. Also the tweeter has a steeper "Shoulder" and Phase fits better. The resistor 3 Ohm in the midsection has to be evaluated by your ears and in your room.

Good luck.

[Chaomaniac]

The SC 10 N will not work well at frequencies far below 3 kHz.
Why do you want to use 2 different tweeters?

[brkl]

The SC 10 N will not work well at frequencies far below 3 kHz.
Why do you want to use 2 different tweeters?

Ah, I suppose I should have known that. The frequency response simply seemed flat where I needed to bridge the gap between the tweeter and bass. Also, it was cheap I'll have to look at some other driver. Thanks

Also, thanks for taking a look at the crossover, walwal! I'll compare them and study what you changed.

[walwal]

Chao is right, i think. i had a blackout. Take the Al 130 (not cheap, but very fine) and you will be satisfied.

[zxlimited]

Hello brkl,

here´s my proposal for your speaker. Take the W 130 S as midrange. It is way cheaper than the AL 130 but still a very good midrange driver.
I optimized your simulation in order to obtain a very flat frequency response and good phasing. You can check for correct phasing very easily: Just reverse the polarity of one driver. You should see a deep dip in the overall frequency response where the two drivers cross. If the dip is not very deep, it is not optimal. If you have no dip at all or even at some points the overall SPL in the transition region is higher than the SPL of a single driver, you´ve done something terribly wrong

Please note that, as the W 130 S is a cone driver which is open at it´s rearside, you need an extra housing for it. You cannot put it in the same housing with the W 250 S! Just build a little wooden box or take a flower pot or something and glue it behind the hole of the W 130 S from the inside of your cabinet. The volume should be around 3 Liters, according to my simulation.

Best regards, Martin

[zxlimited]

Ah, almost forgotten: Does anybody of you also have a wrong/incomplete dataset of the DTW 72? When I load it, it has many values = 0 . That´s why it doesn´t give you a result for max SPL for example. As I didn´t thoroughly check what else might be wrong, I took the DT 94 instead.

[jama]

I would have a light modification in martin's simu...

The sound will so be warmer and English...

[GabbaGandalf]

OT

@zxlimited: Yes, the DTW 72 Data seems to be incomplete in my Boxsim too.
To use this driver i just assume Pmax=5W and xmax =0.1mm.

[brkl]

You really are a helpful bunch!

Yes, I think W130S would suit this project better than AL130. Simply because of cost. Thank you very much for taking the time to edit the project!

I don't like that dip in the highest frequencies that DT 94 has, but I suppose beggars can't be choosers. I can probably live with it. Very strange about the missing data of the DTW 72, good thing I didn't just start building!

Jama, is your modification just to change the impendance, or both the impedance and the frequency response? I'd prefer neutral to warm sound. I suppose low impedance would mean that I would have to be careful in regard to what amplifier I use.

There was a nasty dip in frequency response at the W 130 S - DT 94 crossover frequency around 30 degrees towards the top. Since the speakers are quite low, this could be a problem. I switched the places of the tweeter and midrange drivers, which made the dip happen 30 degrees towards the floor -- which is not a problem Any comments about this? Most speakers I see have the tweeter higher than the midrange.

Thanks again for your help

[jama]

@brkl
Can you see the images?

The additional capacitor (22 micro) acts only lies between 200 and 700 hertz...

In dotted line without her.

[Peter K]

Hallo Martin,

sorry, but I think this statement

If you have no dip at all ........you´ve done something terribly wrong

is not correct...

If this happens, you have designed a perfect third Order acoustical Butterworth-Filter.

As far as I am informed , there is nothing wrong about an ideal third Order Butterworth.....

best regards
Peter Krips

[brkl]

@brkl
Can you see the images?

The additional capacitor (22 micro) acts only lies between 200 and 700 hertz...

In dotted line without her.

Ah, sorry, I simply got confused because the scale changed.