WWMTM project

rinx

Member
2007-09-26 5:34 am
Hey all!

Fisrt of all have to tell you that my english is not yet the best but I try to get better:)
I am so far with my enclosure for WWMTM project that I am going to do a filter. So I know that everybody here dont have unlimited time and sometimes its easyer to tell-do your homework before coming to ask here. Well I have done so far homework on DIY field as posseble, but what is most harder for me is doing a filter. I am not so good in such techikal area, sometimes they say its mix from art and knolidge.
So, what I am looking is that somebody just can delve into my project.
I will give you information as much as posseble to make best decision. Most important is form me XO points and do I need to use notch or other things in filter.

Here is speakers I am using:
http://www.partsexpress.com/pdf/295-366g.pdf
http://www.hautparleur.fr/_audax/am130z2.jpg
http://www.madisound.com/catalog/PDF/seas/h881.pdf

Best regards from Ringo
 
I'm not an expert in this area, I readily admit that.

Your woofer and tweeters look reasonable, but I'm not sure about the Midrange (Audax AM130Z2). It seems very good on the low end, but not so great on the high end. It doesn't look like it will crossover much higher than 2000hz or at the most 3000hz. That is probably a comfortable place for the Seas H881 tweeter, but it is at the limit of the Audax Midrange.

Of course, this is just my limited opinion.

I think (again limited knowledge) that the woofer has to crossover low; 800hz or below.

Fortunately, your Midrange has a very low resonance and looks flat down to about 150hz to 200hz.

There are many other things to consider, but on a superficial analysis, I would say you could crossover Woofer-to-Mid any where in the range between 350hz and 800hz.

On the high side (Mid-to-Tweeter), I don't think you can go much higher than 2000hz to at the most 2500hz.

For the moment, I'm assuming 12db per octave crossovers, but if you need to push you Mid up higher, then you might want to consider 18db/octave.

I'm not saying 'Do This', I'm merely saying, in my limited opinion, these are the working ranges you have.

Whether these are practical ranges, I don't know. I have seen commercial ready-made crossovers that crossover at 375hz/3000hz, 500hz/4000hz, 625hz/5000hz, and others. These seem to be trying to maintain a 3 octave range across the midrange.

That is about the limit of what I can say. I would suggest finding some Crossover modeling software, and trying various crossover points and slopes, and see which works best.

Steve/bluewizard
 

rinx

Member
2007-09-26 5:34 am
Good job!
But yes unfortunately I dont have such technical knowledge about doing really good filter + right now dont have equipments to measure speakers or whole system.
I have some software, like SpeakerWorkShop and LSPCad, but again I am lack of knowledge. In our language there is not enough material also to read.
Kind a trouble:)
 

BlueWizard

Member
2007-06-29 8:49 pm
Have you already purchased your speakers, especially the Midrange?

If you change to a different midrange, you might be able to make this work.

You could consider a Tang Band full range for the Midrange speaker. You can pick anyone you want but these two might do the job -

Tang Band W3-879SC 3" Shielded Driver (264-810) $19.25 each

Tang Band W4-654SE 4" Shielded Driver (264-816) $20.28 each

http://www.partsexpress.com/webpage.cfm?webpage_id=3&CAT_ID=49&ObjectGroup_ID=576

You might want to consider the -

Dayton DC50F-8 2" Dome Midrange (285-010) $31.96 each

http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=285-010

My guess is that it is good from about 600hz to 800hz on the low end, to about 4,000hz or at the absolute most 5000hz on the high end.

As to Crossovers, you have a complication in that you are using TWO woofers, presumably 8 ohms each and presumably wired in parallel. That makes your woofer section 4 ohms, while your Mid and Tweeters are 8ohms. Not a problem if you are designing your own crossovers, but difficult for ready-made crossovers because they are usually designed assuming one impedance across low/mid/high.

One option would be to get 4 ohms woofers (Dayton makes them) and wire them in series for 8 ohms total. Another option, is to get Dual Voice Coil woofers (again Dayton makes them as well as others) wire the voice coils series for 16 ohms, then wire the woofers in parallel for 8 ohms.

These things are never easy.

Steve/bluewizard
 

rinx

Member
2007-09-26 5:34 am
Well, the thing is that I already have all those speakers. I have read about Audax a very good feedback, some people say they are one of the top midrange speakers, so thats why I wanted to use those and see how they sound.

One thing I would like to know is about phase, what I should consider in that case. What I should look about phase and does filter change phase?! and so on..
 

BlueWizard

Member
2007-06-29 8:49 pm
Regarding Low Bass/Mid crossover being low, it hinges on the midrange and tweeter you have. If you crossover low, that lowers the Mid/High crossover as well which makes it easier to find a Midrange but harder to find a Tweeter. It also hinges on how you define 'Low', do you mean 150hz low which is common in Subwoofers, or do you mean 500hz low, which is low for a standard 3-way design, or do you mean 350hz low, and again, can you find speakers to sufficiently span the necessary range?

Also, you say THE woofer is on the side, but your design has TWO woofers, are one or both of them on the side? If one is on the side, you might want to configure them in a Sub (side woofer), Mid-Bass (front woofer), Mid, and Tweeter combination. That complicates things, but is frequently done.

When you are shopping for speakers, you can't just go by the rated frequency response. A quick look at the Frequency Response Chart will tell you that specification can't be trusted. If the Frequency Response graph has high end peaks, as you commonly find in aluminum woofers, then you are going to have to stay away from those frequencies. You are going to have to crossover low or with a very steep slope or insert a filter specifically to reduce those peaks to make sure those peaks are sufficiently attenuated when you reach that frequency. Others have recommended to me that I leave a 3 octave gap, actually it's 36db attenuation, between the crossover and the trouble frequency. Again, this isn't a hard and fast rule, just a quick and easy guideline. So, as in the Daytons, with a peak at 7khz, you are going to have to crossover at 875hs or lower with a standard 12db/octave crossover.

Your Mids are easily going to have to functionally span the gap between where your woofer ends and your tweeter begins. As a general rule, you want to cross your tweeters over well above the resonance frequency of the tweeter. Most recommend 2 octaves above the resonance, but that's not an absolute rule, just a guideline. If you understand crossover design, you can crossover closer to the tweeter resonance, but in general, you want to stay away from it.

For both Midrange and tweeters, the listening field, or off axis response, will start to narrow as the frequency goes higher. For Mids, you want to stay out of this area as much as possible, that limits the available high end response of the Mids. Tweeters will frequently have a peak or a drop as they approach the 10khz to 20khz range. You need to decide if you can live with those inconsistencies as they are or whether you are going to have to compensate for them in the crossover design.

This is what makes choosing speakers and designing crossovers such a complex process. It is not as simply as matching speaker by their rated frequency response. You really have to study the Frequency Response and Impedance graphs and pay attention to dips and peaks as well as off axis response.

Hope that helps.

Steve/bluewizard
 
For experience sake and to figure out the phase realtionship (besides other things) I always build cheap separate enclosures with the correct (and calculated) volume for each involved chassis. This way you can shift them back and forth until the phase relationship (distance from the listening position) is perfect. Of course you need a preliminary version of the cross-over before you start this task. You'll see later on that changing the position will have an influence on the cross-over and vice versa. Further changes to the cross-over etc. are more likely to happen.
Another hint: make the enclosures as flat as possible in particular when using an MTM arrangement (D'Appolito setup). Then stack them in the order you had in mind - i.e. WWMTM, WMTMW, ...

That's so far the basic setup as a starting point for any measurements.

:bawling: The pitty is that you don't have (according to your own words) any measurement equipment at all. And right here IMHO ends all your efforts because of lack of an appropriate equipment :bawling: .

You desperately need some sort of audio measurement hardware and/or software :xeye: .
Without - it might be a painful trial and error method just based on hearing experiences and the result is more likely to satisfy only you and nobody else. :cannotbe:
 

rinx

Member
2007-09-26 5:34 am
Well, yes I have two woofers on side.
I am thinking that I should go approx 250hz, can I do that and will keep Mid/Tweeter XO approx. 2000-2500.
So then I should do first filter and start looking how well is my target? Also phase track, and when its not good start modifying filter?!


By the way, why I need active sub plateamp?! And if I am doing WWMMT, and MMT 2.5 system, then I am gonna have 3 XO points?!
1) Woofers/first mid
2)first mid/second mid
3)second mid/tweeter

My enclosure is pretty much done. Why I decided to put Woofers on side, is design, because I wanted front baffle to be narrow as posseble, and right now it is 20cm with lenght 145.
I am gonna do something like that:
http://www.audes.ee/?id=1840&tpl=1020

I have heard those, they sound OK, nothing really special. I think I can do better than those, because the speakers I use should be better (distortion and sound).
I have some software-SpeakerWorkshop, plus I bought Behringer mic to measure speakers. But I still feel that I am lack of knowledge how to create a good filter and how to chose speakers that will work together really well.
 

tinitus

diyAudio Moderator R.I.P.
2005-11-24 1:47 am
With the woofers on the sides I wouldnt cross higher than 100hz, hence the active plateamps, hence the 2.5way midsection

In line with that I suggested the MMT in a 2.5way to give you some BSC to compensate fore the SPL loss below 500hz
2.5way means that both mids will play midbass, but only one will play upper midrange...quite simple to handle
It could be regarded as a 2.5way with subs...yeah, it a compromise,which there will always be

"Standard 3way" WWMTM is much more complicated with the need fore low upper xo point and steep filters, not recommendable without measurements

Its easier to handle mid/tweeter xo with only a single driver playing mids

But its your game so your are free to choose what you like best
 
Well, it's a compromise, but your existing components might support a 375hz & 3000hz crossover. That is generally regarded as a very low crossover for a standard 3-way system. That is also pushing the upper limits of your midrange. It's not terrible at 3000hz, but lower would be better. Crossing over that low should leave the break up at 7khz well out of the circuit. If you are custom designing a crossover, then try to squeeze the Mid/High crossover a little lower. Still, everything is a compromise, we have to do the best we can with what we have.

Also, while I can say this can be done, I'm not able to say it should be done, there are many other factors to consider that are beyond my limited knowledge.

Now all you have to do is design the crossover and the box. Shouldn't be that hard (he said with a wry sarcastic smile).

Good luck.

Steve/bluewizard
 

rinx

Member
2007-09-26 5:34 am
Ok, thansk a lot! You made some things to me a much more clear.
So, what I decided is that I am planning to do Woofer/Mid 200Hz and then MMT 2.5 system. i just try and we will see how does it sounds.
So, the question is where I should stop First Mid?
I understand that Second Mid is going to approx. 3000Hz, I would say 2750-2800 is good.
 

tinitus

diyAudio Moderator R.I.P.
2005-11-24 1:47 am
Not sure about this...but anyway, here is a rough schematic of how it could look like... simplified and with estimated values
 

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I'm not really sure you understand what Tinitus is saying. I think he is saying you need to change your whole design approach, and skip the WW and just go with MMT. Or he is saying modify your existing design into what we might call a 3.5 system.

In your design, if you incorporate Tinitus's principles, you are simply adding a .5 to an existing 3-way system as seen in the attached diagram.

In my example/diagram, between 20hz and 200hz both Bass-1 and Bass-2 (WW) are in the circuit, but above 200hz Bass-1 starts to fade out and Bass-2 takes it the rest of the way to the normal 3-way crossover.

In a 2.5way system, as is commonly found in TMM systems, the 'M' stands for MidBass, not just Mid. Again, at low bass frequencies, both MidBass drivers are in the circuit, then one fades out, and the other MidBass carries the high-bass and mids up the the crossover point of the tweeter.

If you apply Tinitus's idea to your existing design, you are in a sense adding another component to the crossover system.

I think Tinitus, though he is free to correct me, is telling you to, in a sense, start over with a completely new design philosophy which will probably mean buying different speakers, which you don't seem to want to do.

Trying to crossover BOTH woofers at 200hz to the Mids, then crossing over from mid to high in the 3000hz range is less than ideal, but still possibly workable. You are getting down near the bottom end of your Mids workable range, and I would still recommend a minimum 375hz crossover bass/mid. Also, keep in mind that if you drop your low/mid crossover to 200hz, you can lower your mid/high crossover to 1600hz, but that's too low for your tweeter. But, I think it still might be functional in the 2000hz to 2500hz range.

Since you now have these odd and unusual crossover points, you will either have to design your own crossovers, or you will have to use two 2-way crossovers, assuming you can find them. One 2-way the crosses over at 200hz, and another 2-way that crosses over at 2500hz, feed the second with the High Out of the first.

But, every design is a compromise and every design is an experiment. So, try it, if you don't like it, you can always change it later.

Crossing over lower doesn't necessarily give you more bass. It only isolates the bass that is already there. I think that is the first flaw in your design.

Personally, in a straight 3-way system, I can see no point in crossing over below 500hz, but that's just me.

In short, I don't think you (or perhaps I) understand what Tinitus is getting at, and I don't think you are going to gain what you think you are going to gain by crossing over so low.

If you insist on using these speakers in at 3-way configuration, I would go with a straight 3-way 375/3000hz crossover. But using Tinitus's idea with your concept and your speakers doesn't necessarily help you. You still need a standard 3-way crossover for a WMTM confirmation, and an additional crossover component for the remaining W component to give you a W+WMTM configuration.

Tinitus?? Clarification??

Steve/bluewizard
 

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tinitus

diyAudio Moderator R.I.P.
2005-11-24 1:47 am
A bit confusion it seems :confused: but to me it seems that Rinx understood perfectly clear

1. I suggested to use active plateamp on woofers, with low xo point.... mids and tweeter in 2.5way configuration...not intended fore insane SPL

2. Rinx wants a somewhere in between with a 200hz xo point, with the mids in 2.5way...hence the shown filter is fore mids solely, woofers are still running straight in paralel

3. Bluewizzard, your suggestion may be fine, but you still have to consider that woofers are mounted on the sides, which may result in strange and problematic phase behaviour, especially with higher xo point

BTW...I dont suggest other drivers and if it wasnt the case that Rinx already had these drivers, I wouldnt suggest anything other than to build a wellknown and proven design
 
OK, now I've got it.

Yes, I certainly was confused. But Tinitus's new explanation makes it clear. If that is Rinx understanding then we are perhaps on the right track.

Still for the mids, a 200hz crossover is pushing it. That strikes me as the absolute limit on the low end. If he wants to try that, no problem, if it doesn't work out he can always try something else. Or, am I again misunderstanding?

Thanks for the clarification.

Steve/bluewizard
 

tinitus

diyAudio Moderator R.I.P.
2005-11-24 1:47 am
We agree that 200hz is low and demands fore bigger components, but in this case with side woofers I think its an ok compromise, and mids will take care of some BSC too
like you say it will not be so hard to make changes if needed, as long as its kept as simple as possible, woofers though will need inductors around 10mH
 

rinx

Member
2007-09-26 5:34 am
Ok, I understand what you both are meaning. I can thruly say that filter area is really complicated for me. We do not have literature in our language, so its not easy to understand such a techikal things in englis, well I try!
So, can I do so, I will first finish enclosure and then mount all drivers and start measuring phase, freq range and so on?! After that I can decide how to do filter?!

By the way, I am mounting woofers on side, I was thinking about that....fisrt I have heard that there is no difference for woofers, where they are located (it seems that still is), so to compensate that my woofers are a side, should I turn them a littlebit towards to the listeners point?! Maybe 15 degrees...did you understand what I mean?
Does it makes things better/ is there difference?
Maybe I can go then with W/M x-o pint towards 300-400Hz (I would agree with BlueWizard, that a littlebit higher is better for Mids).