The towers I am building will measure 49"H x 7.75"W x 12"D, with the front baffle being 49" x 7.75". I want to create an MTMWW design, sectioning off the woofers into their own ported space. The space for the woofers will be 1.16 cu ft, leaving .55 cu ft for the midranges and tweeter.
The drivers:
Tweeter - Dayton Audio PT2C-8
Midrange - Dayton Audio ND105-4
Woofer - Dayton Audio DA175-8
I'll add some additional bracing, but the interior of the box will consist of 2 chambers, the bottom one for the woofers, which will be ported, and the top chamber for the midranges and tweeter, which will be sealed. Would someone be able to use some modeling software to help create a crossover system? I'm fairly open to different driver suggestions if these don't pair well. The amp needs to see between a 6 - 8 ohm load. At this point, the only reason of the mention of the center channel, is because I would like to use the same midrange, tweeter, and crossover (minus the woofer) in an MMTMM design, and would also like some input on that idea.
I'm extremely new to speaker building so any and all advice/criticism is welcome.
The drivers:
Tweeter - Dayton Audio PT2C-8
Midrange - Dayton Audio ND105-4
Woofer - Dayton Audio DA175-8
I'll add some additional bracing, but the interior of the box will consist of 2 chambers, the bottom one for the woofers, which will be ported, and the top chamber for the midranges and tweeter, which will be sealed. Would someone be able to use some modeling software to help create a crossover system? I'm fairly open to different driver suggestions if these don't pair well. The amp needs to see between a 6 - 8 ohm load. At this point, the only reason of the mention of the center channel, is because I would like to use the same midrange, tweeter, and crossover (minus the woofer) in an MMTMM design, and would also like some input on that idea.
I'm extremely new to speaker building so any and all advice/criticism is welcome.
Last edited:
Unfortunately my lack of woodworking skills and tools means they won't be changing a whole lot from start to finish... I found some nicely rated veneer on parts express that I want to try. I can prep the wood and everything, but I don't have anything for forming shapes; I might buy a router to round off the front baffle, but that'd be it. I need to edit and reword my main post since I think its a bit too scatter brained and asking for too much at once, but I think I have my drivers picked out. I need to measure inside to find the exact volume, but I want to section off the 7" woofers into their own compartment and tune it with a port, while the leaving the mid ranges and tweeter in a separate sealed compartment. Wherever I add the plank for the woofers, I'll count that as a brace, and maybe add a few at the top, with some holes in them so they won't seal off any other areas.
Any and all advice is welcome, I think I'm becoming pretty dead set on using (from top to bottom) MTMWW for the main speakers. I keep reading that MTM designs have good lateral dispersion and limited vertical dispersion, which would be perfect for our rather small basement with standard 8ft ceilings. I'm far from an audio engineer, but that plus ribbon or planar tweeters should help me achieve a pretty wide sound stage, wouldn't it?
Any and all advice is welcome, I think I'm becoming pretty dead set on using (from top to bottom) MTMWW for the main speakers. I keep reading that MTM designs have good lateral dispersion and limited vertical dispersion, which would be perfect for our rather small basement with standard 8ft ceilings. I'm far from an audio engineer, but that plus ribbon or planar tweeters should help me achieve a pretty wide sound stage, wouldn't it?
Could I use this, except wire the woofers and midranges in parallel with each other? It has a 2db bandpass gain which will help the midranges spl match the woofer's, and then I could use an l-pad for the tweeter. Assuming I would wire the other 2 speakers in my MTMWW in parallel with their match, using 8 ohm speakers would result in each driver circuit (mid or woofer) seeing a 4 ohm load, is that right? Then wire the woofers to the mids in series, to bring the load back to 8 ohms, then the tweeter in... series with the mids?
An externally hosted image should be here but it was not working when we last tested it.
My friend, I think this is WAY too ambitious for a first project. You don't even have a crossover, and I suspect 4 ohm midrange will take impedance far too low. Even conventional 3-ways often hover around 4 ohms impedance.
3-Way Classic
You COULD take any good conventional 2-way design, and double up the woofers wired in series for the same SPL or loudness. The bass crossover gets coils and resistors doubled up in value, and the capacitors halved in value, by one of those neat quirks of the maths. The treble filter is unaffected. That gets you your MTM with a highish impedance. Come to think of it, you could do something similar with a 3-way.
The parallel wired MTM, by contrast, takes impedance lower and drives the tweeter harder.
I don't think anyone here has the time to nurse you through this, so I'd suggest you build an established design within your capabilities.
DIY Loudspeakers
3-Way Classic
You COULD take any good conventional 2-way design, and double up the woofers wired in series for the same SPL or loudness. The bass crossover gets coils and resistors doubled up in value, and the capacitors halved in value, by one of those neat quirks of the maths. The treble filter is unaffected. That gets you your MTM with a highish impedance. Come to think of it, you could do something similar with a 3-way.
The parallel wired MTM, by contrast, takes impedance lower and drives the tweeter harder.
I don't think anyone here has the time to nurse you through this, so I'd suggest you build an established design within your capabilities.
DIY Loudspeakers
I didn't want to sound too discouraging, but I do think you're taking on a huge project there. At least, for someone new to this. 
I can suggest you look at some similar projects, like this Visaton Experience V20:
EXPERIENCE V 20
Visaton provide a free Sim program called Boxsim:
Downloads
They also give away the BPJ project files which you can copy to the projekte folder in Boxsim, and it has done all the work for you including cabinet:
Boxsim Projektdatenbank Experience V20
Maybe not exactly what you are looking for, but you could then try Visaton's own ribbon tweeter in the sim and see how it all looks. Boxsim is incredibly versatile when you get to know it. You can fiddle with cabinets and optimise to your hearts content. I got the hang of it in a couple of hours. Probably best to learn your way round with a simple 2-way at first.
BTW, your idea of wiring the drivers in series with an MTM to raise the traditionally low impedance is quite feasable. You can do that in the sim too.
I can suggest you look at some similar projects, like this Visaton Experience V20:
EXPERIENCE V 20
Visaton provide a free Sim program called Boxsim:
Downloads
They also give away the BPJ project files which you can copy to the projekte folder in Boxsim, and it has done all the work for you including cabinet:
Boxsim Projektdatenbank Experience V20
Maybe not exactly what you are looking for, but you could then try Visaton's own ribbon tweeter in the sim and see how it all looks. Boxsim is incredibly versatile when you get to know it. You can fiddle with cabinets and optimise to your hearts content. I got the hang of it in a couple of hours. Probably best to learn your way round with a simple 2-way at first.
BTW, your idea of wiring the drivers in series with an MTM to raise the traditionally low impedance is quite feasable. You can do that in the sim too.
Last edited:
Hi, I'm not a wood pro, but I can work a jigsaw and a router. I would ENCOURAGE you to start with the recommended project. Nothing worse than disappointment at your first try. Having built several 2- 3 way small speakers and now working on a big (2 cabinet 51 inches high) system, the hardest hart isn't the wood, it's the crossover !!
Again, a first attempt pre designed kit will really encourage you to do something more to what you like as your next attempt. Be warned, there will be many.
The DIY audio community will assist you as you go. They've helped me a lot.
Again, a first attempt pre designed kit will really encourage you to do something more to what you like as your next attempt. Be warned, there will be many.
The DIY audio community will assist you as you go. They've helped me a lot.
As it goes, I believe the drivers for Visaton are available in the US, Jvsantosmd.
There IS a way of making your own MTTM easily enough out of two-ways. You'd probably want to get the tweeters as close as possible to each other, but there is a school of thought that MTTM works even better than MTM because it matches the drivers for a cylindrical response.
Not as daft as it looks.
There IS a way of making your own MTTM easily enough out of two-ways. You'd probably want to get the tweeters as close as possible to each other, but there is a school of thought that MTTM works even better than MTM because it matches the drivers for a cylindrical response.
Not as daft as it looks.
Attachments
Thanks for the posts guys. System7, I checked out those links in your first reply, there are some really good designs. I have some questions about PCD if anyone is familiar with it. I admittedly havent read the manual yet so ignore these if they are super easy questions, but I did search and skim the manual, (search isn't the most friendly in excel).
If I'm trying to build a speaker for an 8 ohm receiver, what is the minimum recommended system impedance that should show? I get dips down to 3 ohms, I have a feeling it would throw my receiver into autoprotect almost right away.
Phase - I know phase is vital when talking about left and right phase of stereo speakers, so I bet it's just as important with crossovers. How far off can phase be before I would be able to hear it in the speakers? Do all the vertical phase lines need to be lined up, dead accurate?
System response vs power response. System response is what I'll actually hear, and power response is what the drivers are actually playing, is that correct?
How do I get PCD to display a wiring schematic?
If I'm trying to build a speaker for an 8 ohm receiver, what is the minimum recommended system impedance that should show? I get dips down to 3 ohms, I have a feeling it would throw my receiver into autoprotect almost right away.
Phase - I know phase is vital when talking about left and right phase of stereo speakers, so I bet it's just as important with crossovers. How far off can phase be before I would be able to hear it in the speakers? Do all the vertical phase lines need to be lined up, dead accurate?
System response vs power response. System response is what I'll actually hear, and power response is what the drivers are actually playing, is that correct?
How do I get PCD to display a wiring schematic?
I know it's a project that's over my head, but I'm determined to learn and build something to replace our home theater speakers. I'm not dead set on the MTMWW design, after realizing the amount of work that would go into it. I have been messing around with PCD and although I haven't changed any of the values to real values that can easily be found (33uF vs 35.4uF). I'm not jumping and spending any money on parts for a while, until I'm certain that whatever I come up with, will work and sound good. Can someone explain how I am supposed to align the driver phases?
An externally hosted image should be here but it was not working when we last tested it.
This is no trivial pursuit! Begin here and follow all the links to get an idea what you're up against and why few pursue it: Design_of_the_sound_system
GM
GM
Good phase comes with the filter topology usually. A 3-way, which is what you are really designing here, has certain styles of filter that just line up nicely on phase.
Start with this Troels design and similar drivers, and you should be close to lined up on phase anyway. It is a classic filter design.
3-Way Classic
I don't know how your software works, but in Boxsim, you just mark a few components in red and click on "optimise". I would add a couple of attenuator circuits on the mid and tweeter to let Boxsim adjust levels too. It does a decent job of adjusting for flat response and good phase and impedance usually. 3-ways are quite hard, but you'll get there. Phase should be matched within 10 degrees at crossover IMO.
Converting to an MTM style is then fairly trivial. I explained how you do it earlier. I also suggested you started with a two-way, because it's easier, but you're not listening.
Last edited:
For an AVR receiver spec'd for 8ohm speakers you are definitely good with a 6ohm minimum. Below that, the answer is it depends. You are probably good with 5ohm minima if the impedance phase angle is also benign. You might be good down to 4ohm if the phase angle is also shallow and you are not pushing the low frequencies through the speakers (ie, you are crossing at 80Hz to a sub) and you are not playing them very loud and the minimum impedance isn't at the lowest frequencies. Might. This article might offer you a little more insight.
Setting the A/V Receiver Impedance Selector Switch | Audioholics
So smartest thing to do would be to keep the speaker impedance above 5 or 6ohm and cross all speakers to your sub at about 80Hz. This means you don't really need a 3-way, though you can still go that way if you want.
You also have to live with the impedance you get when you wire 2 drivers together either series or parallel in each specific "way" - the tweeter, mid and woofers in a 3-way are already effectively wired in parallel but their impedances operate separately when they each have their own xo's.
So for your AVR, 2 x 4ohm mids either series but definitely parallel won't work. Even 2 x 8ohm drivers in parallel in a 3-way are probably going to result in a minimum impedance too low for your receiver. You must wire them in series or choose a higher impedance driver. Parallel is the better choice because you get an extra 6dB of sensitivity out of them and that means that your receiver has to do less work which is what you want.
You might want to look at something from GR Research who make some of their drivers in 16ohm versions. Speaker kits, loudspeaker design services, sub-woofers and amplifiers. - Drivers
The MTM decision is not a bad choice for your situation. Nor is the ribbon or planar choice. However the choice of a tall ribbon or planar means a larger center-to-center spacing between the mids which you want to keep as tightly spaced as you can. This might be a better choice but there are others too: Fountek NeoCD1.0 Ribbon Tweeter | 296-701. Even better if you cut the flange off at the top and bottom. There's also an advantage to choosing small mids in this respect and this works well too when converting the design to a center channel. I would try to keep the WMTMW format there as well. In home theater, the center channel is really the most important speaker. That and the sub(s).
You are on the right track with PCD. Stick with that. Phase in your example is well aligned where it needs to be - where the driver frequencies combine together in the xo regions. Having the vertical part of the phases line right up at the xo's is perhaps ideal but isn't necessary - sometimes the phases will track together for a greater frequency range at other points. Reverse the polarity on the mid in a 3-way and you will also see deep nulls at the xo's when the phases are properly aligned. But do yourself (and us) a favor and read the manual completely.
Power response is a mathematical construct of the total frequency response in 360* space, ie all around the speaker. It is correct for it to be lower in the higher frequencies. It's important because you hear not just the direct, on-axis sound but also the reflections of sound from all around the room.
PCD or any other program is only as good as the data that you feed in to it, so make sure that you get that right too. Box response, baffle diffraction and extracting minimum phase must be done correctly or you're just working with bad data. It can help to be using reliable 3rd party data when you are unable to measure yourself. Try Zaph|Audio. Some manufacturer's data are not to be completely trusted.
For more info, try the following:
The Speaker Building Bible
https://sites.google.com/site/undefinition/simulated-measurements
Designing Crossovers with Software Only
http://audio.claub.net/Simple%20Loudspeaker%20Design%20ver2.pdf
Tips, Volume 2- The setup!! - Blogs - Techtalk Speaker Building, Audio, Video Discussion Forum
Some optimization criteria... and some tips... - Blogs - Techtalk Speaker Building, Audio, Video Discussion Forum
https://app.box.com/s/3oybwh0qtil8qj9knd2l
And a PCD video (download for the whole thing):
https://www.dropbox.com/s/v73tkc8bywsm5nb/Untitled%208.avi
That should keep you busy for a while.
Setting the A/V Receiver Impedance Selector Switch | Audioholics
So smartest thing to do would be to keep the speaker impedance above 5 or 6ohm and cross all speakers to your sub at about 80Hz. This means you don't really need a 3-way, though you can still go that way if you want.
You also have to live with the impedance you get when you wire 2 drivers together either series or parallel in each specific "way" - the tweeter, mid and woofers in a 3-way are already effectively wired in parallel but their impedances operate separately when they each have their own xo's.
So for your AVR, 2 x 4ohm mids either series but definitely parallel won't work. Even 2 x 8ohm drivers in parallel in a 3-way are probably going to result in a minimum impedance too low for your receiver. You must wire them in series or choose a higher impedance driver. Parallel is the better choice because you get an extra 6dB of sensitivity out of them and that means that your receiver has to do less work which is what you want.
You might want to look at something from GR Research who make some of their drivers in 16ohm versions. Speaker kits, loudspeaker design services, sub-woofers and amplifiers. - Drivers
The MTM decision is not a bad choice for your situation. Nor is the ribbon or planar choice. However the choice of a tall ribbon or planar means a larger center-to-center spacing between the mids which you want to keep as tightly spaced as you can. This might be a better choice but there are others too: Fountek NeoCD1.0 Ribbon Tweeter | 296-701. Even better if you cut the flange off at the top and bottom. There's also an advantage to choosing small mids in this respect and this works well too when converting the design to a center channel. I would try to keep the WMTMW format there as well. In home theater, the center channel is really the most important speaker. That and the sub(s).
You are on the right track with PCD. Stick with that. Phase in your example is well aligned where it needs to be - where the driver frequencies combine together in the xo regions. Having the vertical part of the phases line right up at the xo's is perhaps ideal but isn't necessary - sometimes the phases will track together for a greater frequency range at other points. Reverse the polarity on the mid in a 3-way and you will also see deep nulls at the xo's when the phases are properly aligned. But do yourself (and us) a favor and read the manual completely.
Power response is a mathematical construct of the total frequency response in 360* space, ie all around the speaker. It is correct for it to be lower in the higher frequencies. It's important because you hear not just the direct, on-axis sound but also the reflections of sound from all around the room.
PCD or any other program is only as good as the data that you feed in to it, so make sure that you get that right too. Box response, baffle diffraction and extracting minimum phase must be done correctly or you're just working with bad data. It can help to be using reliable 3rd party data when you are unable to measure yourself. Try Zaph|Audio. Some manufacturer's data are not to be completely trusted.
For more info, try the following:
The Speaker Building Bible
https://sites.google.com/site/undefinition/simulated-measurements
Designing Crossovers with Software Only
http://audio.claub.net/Simple%20Loudspeaker%20Design%20ver2.pdf
Tips, Volume 2- The setup!! - Blogs - Techtalk Speaker Building, Audio, Video Discussion Forum
Some optimization criteria... and some tips... - Blogs - Techtalk Speaker Building, Audio, Video Discussion Forum
https://app.box.com/s/3oybwh0qtil8qj9knd2l
And a PCD video (download for the whole thing):
https://www.dropbox.com/s/v73tkc8bywsm5nb/Untitled%208.avi
That should keep you busy for a while.
Hi,
Build a pair of these and the matching center :
Zaph|Audio - ZDT3.5
Ponder the design details at your lengthly leisure
whilst you build something properly designed.
rgds, sreten.
Getting a passive crossover right is challenging for anyone. You have to know the impedance of the driver at the frequency you want to cross it over at. This is not likely to be very close to the advertised "nominal" rating. Then you have to equalize their efficiencies with resistors, before you can calculate the size of the reactive components (coils and caps). Then you need to consider baffle step response, and decide how you're going to deal with that, if at all. If the speaker will be out from any walls, baffle step is a pretty big thing. The size of the baffle will be one issue, and at lower frequencies any walls will come into play in a similar way.
Pay close attention to the frequency response graphs when choosing the crossover frequencies. Phase matters a lot when you are adding the output of two drivers at a crossover frequency. If the crossover components cause more than 90 degrees of differential phase shift, you'd need to reverse the wires on one of the drivers, relative to the other. I wouldn't worry about absolute phase, it's arguably inaudible. If the crossover is more than a one pole design, errors will be bigger. Everything will need to be very exact. Without proper equipment and knowledge, you'll be shooting in the dark.
I'd recommend picking one of the speaker projects at Zaphaudio.com. He's very sharp, has good well tested designs, and maybe the best bang for the buck.
Pay close attention to the frequency response graphs when choosing the crossover frequencies. Phase matters a lot when you are adding the output of two drivers at a crossover frequency. If the crossover components cause more than 90 degrees of differential phase shift, you'd need to reverse the wires on one of the drivers, relative to the other. I wouldn't worry about absolute phase, it's arguably inaudible. If the crossover is more than a one pole design, errors will be bigger. Everything will need to be very exact. Without proper equipment and knowledge, you'll be shooting in the dark.
I'd recommend picking one of the speaker projects at Zaphaudio.com. He's very sharp, has good well tested designs, and maybe the best bang for the buck.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.