can someone help build me a passive crossover design?

[illnastyimpreza]

I am looking to build a passive crossover for a double mid, & single tweet settup.( this is a MTM home speaker) Is there anyone who can help me make one? Or Is there some good free web based software I can use to determine crossover components?

Peerless India W6-KA638-SH 6.5" Paper Cone Shielded Woofer
Peerless India W6-KA638-SH 6.5" Paper Cone Shielded Woofer | Parts-Express.com
Specifications: *Power handling: 40 watts RMS/80 watts max *VCdia: 1" *Le: 0.73 mH *Impedance: 8 ohms *Re: 5.0 ohms *Frequency response: 55-6,000 Hz *Fs: 67 Hz *SPL: 85.1 dB 1W/1m *Vas: 0.63 cu. ft. *Qms: 3.32 *Qes: 1.43 *Qts: 1.00 *Xmax: 3 mm *Dimensions: Overall diameter 6-1/2", Cutout diameter 5-3/4", Depth 3-5/8".

Dayton DC28FST-8 1-1/8 Dayton DC28FST-8 1-1/8" Silk Dome Truncated Shielded Tweeter | Parts-Express.com
Specifications: *Power handling: 50 watts RMS/75 watts max *VCdia: 1-1/8" *Impedance: 8 ohms *Re: 5.6 ohms *Frequency range: 1,600-20,000 Hz *Fs: 749 Hz *SPL: 89 dB 1W/1m *Dimensions: A: 4-5/16", 3-11/32" across flats, B: 3-1/8", C: 1-1/2"

How do I build the crossover in order to acheive an optimal 8ohms?

[6L6]

From Troels Graveson -

Most common e-mails go like this: "I have these and these drivers; can you please make me with a crossover?" I can't, because to make a crossover I need this:

- Frequency response and phase from actual drivers mounted on actual front panel.
- Impedance/electrical phase of all drivers mounted in actual cabinet.
- Acoustic distance from drivers to suggested listening point.
- In short: I need your finished speakers on my workshop bench.

In very few cases I may have the actual drivers and a suitable test cabinet and I can set up the drivers and do what's described above. We're then into diy-service work and it usually takes 5-15 hours depending on overall complexity. This only provides a crossover that actually works on some basic parameters like frequency response, phase integration, power response, etc., but no guarantee it also sounds good.

The question is whether we can make a crossover at all without measurements
- and the answer is NO. It cannot be done, and crossovers cannot be calculated.

We cannot use manufacturers' data sheets to simulate crossovers either. The SPL data may be taken from an infinite baffle that does not in any way resemble your cabinet. These data do not contain proper phase data, etc."

Here is the page that this was taken from - http://www.troelsgravesen.dk/crossovers.htm Lots of neat info on his site!

~~~~~~~~~

My suggestion is to buy a kit. The engineering is already done, and you know that the drivers chosen for it will work together. If you want to build your own cabinets, that's a great way to go, lots of fun and very rewarding. If you are after minimum hassle, use the kitmaker's cabinets, most of them these days are rather beautiful.

It's still DIY, and very fun. Also, it is great to know that at the end you will have a great sounding speaker that looks wonderful!!

[illnastyimpreza]

so lets say I just put in the basic perameters for drivers (from the manufacturer) and make a Basic 2nd order crossover. whats the worst that can happen?

Don't most off the shelf speakers use a similar aproach?

I am limited by funds, the drivers I have chosen I can get for under 50 bucks.

Are there any decent MTM driver projects for a super budget price like this?

where is the parts express TRITRIX TriTrix MTM TL Speaker Package: Cabinet Kit and Components | Parts-Express.com gonna come in as far as sound quality? I have seen Zaph's review of those dayton 5'' drivers and they are horible.

I'm just looking to put together an affordable surround system, which gets very expensive when you have 7 speakers as well as a subwoofer !

[6L6]

Originally Posted by illnastyimpreza

so lets say I just put in the basic perameters for drivers (from the manufacturer) and make a Basic 2nd order crossover. whats the worst that can happen?

Read the page I linked. All sorts of nasty stuff can happen, and you will have a speaker that you spent time and money that sounds awful.

Don't most off the shelf speakers use a similar aproach?

No

I am limited by funds, the drivers I have chosen I can get for under 50 bucks.

I suspected that. Good speakers on a budget actually make the xover design much more difficult.

Are there any decent MTM driver projects for a super budget price like this?

Let me see what I can find. Do you want to build your own cabinets? Are you married to MTM? (It raises cost...) What is your budget per speaker/system/etc...?? Any info would be valuable.

I'm just looking to put together an affordable surround system, which gets very expensive when you have 7 speakers as well as a subwoofer !

Well... first, build a 5.1 channel system, the rear surrounds are more of a sales gimmick than something actually worthwhile.

The biggest bang-for-the-buck is a good subwoofer. If you currently have some speakers, adding a good sub (10" or 12" with a decent amp) is the best thing you can do for making your theater sound more impressive. Then build some good front speakers (L C R) and then surrounds.

[Centvrion]

Originally Posted by 6L6

From Troels Graveson -

Most common e-mails go like this: "I have these and these drivers; can you please make me with a crossover?" I can't, because to make a crossover I need this:

- Frequency response and phase from actual drivers mounted on actual front panel.
- Impedance/electrical phase of all drivers mounted in actual cabinet.
- Acoustic distance from drivers to suggested listening point.
- In short: I need your finished speakers on my workshop bench.

Probably you can try this: it's and old an very powerful program to project crossovers; don't take care of the DOS look! It has been written by Renato Giussani more than 20 years ago...see here
I'm sorry but the website it's only Italian, but there's the translation utility.
There are also other interesting and powerful programs, but probably available only in Italian...
I hope it can help!

[Francec]

Go active and save yourself the hassle of the complexities of passive.

Frank

[PeteMcK]

re:'All sorts of nasty stuff can happen, and you will have a speaker that you spent time and money that sounds awful.' - this is a considerable over-exaggeration. With paper cone drivers in particular, while the response may be far from optimal, it will still sound reasonable.
The OP however is making a mistake mistake when trying to 'acheive an optimal 8ohms' - it is clear that he doesn't understand that impedance varies with frequency, and he will need to use the ACTUAL VALUE OF IMPEDANCE AT THE CROSSOVER FREQUENCY (the number of times this has been stated on this forum is approaching the infinite...)

The best way to do this is to run an impedance curve: Download ARTA: ARTA ARTA Download, Make this simple jig: ARTA Jig - AudioBlog: A simple loudspeaker measurement jig for ARTA

The OP will also need to calculate an L pad for the tweeter: L pad calculator - attenuation dB damping impedance decibel loudspeaker speaker - sengpielaudio Sengpiel Berlin

[Centvrion]

I don't want to be insisting, but...the program I've linked above is in english and calculates filtering networks considering all these parameters and also a zobel net if needed. Moreover it can simulate response in a particulare room (volume, floor...), polar response with distance between drivers...etc. I don't believe it exists something similar to an english manual, but you can learn to use it by yourself; however I'm here for any question (I'm only a simple user of the italian version, and I own the italian manual you can find on the website...but I will do what I can).

Try it.

[illnastyimpreza]

Originally Posted by PeteMcK

re:'All sorts of nasty stuff can happen, and you will have a speaker that you spent time and money that sounds awful.' - this is a considerable over-exaggeration. With paper cone drivers in particular, while the response may be far from optimal, it will still sound reasonable.
The OP however is making a mistake mistake when trying to 'acheive an optimal 8ohms' - it is clear that he doesn't understand that impedance varies with frequency, and he will need to use the ACTUAL VALUE OF IMPEDANCE AT THE CROSSOVER FREQUENCY (the number of times this has been stated on this forum is approaching the infinite...)

The best way to do this is to run an impedance curve: Download ARTA: ARTA ARTA Download, Make this simple jig: ARTA Jig - AudioBlog: A simple loudspeaker measurement jig for ARTA

The OP will also need to calculate an L pad for the tweeter: L pad calculator - attenuation dB damping impedance decibel loudspeaker speaker - sengpielaudio Sengpiel Berlin

wow that seems like an AWESOME cheap DIY speaker measurement tool.

I will definitely have to check it out. Have you used this method in the past? how did it go building the jig and everthing?

Does that program take your speaker values and basicly tell you what crossover parts you need ?


CentVrion, thanks for the link, unfortunitely I wasn't able to get the language translator to work at all.

[speaker dave]

Originally Posted by illnastyimpreza

so lets say I just put in the basic perameters for drivers (from the manufacturer) and make a Basic 2nd order crossover. whats the worst that can happen?

It won't destroy the ozone layer, if thats what you mean. It just isn't likely to give a good result.

6L6 and his reference are absolutely correct in that you can't design a crossover that works without the ability to measure the drivers on the cabinet and see the results of the network you apply. You can trial and error a working network without the ability to measure phase or impedance if you can at least measure response, see how the individual networks applied to woofer and tweeter shape the corners, and then see how the sections add up. Search the threads for measuring software and a cheap calibrated microphone.

Short of that, the results will be random and unpredictable. Going active will only be slightly better (the electrical filter will be known but the acoustical combination will not). Knowing the impedance curve, perhaps to textbook design a filter for the "right impedance" will not get you any closer.

Someone should write a sticky thread on this. It comes up so frequently.

David S.