I'm going to be building a pair of tower loudspeakers soon, mainly for a good learning experience more than anything else, but I also want them to turn out good.
These are going to be a 4-way design...
My goals are to have a tower capable of full-range reproduction, be able to play to decent volumes (not loud), be able to play pipe organ music with believable bass extension, have good dynamics for pop/rock/jazz/blues, natural midrange, good, open top-end extension and convincing imaging and soundstaging that equals or betters really good bookself speakers.
So far, I think the driver lineup will be: (per tower)
(4) Dayton DC160-8 Woofers - 8 ohms - 2.25cf ported enclosure tuned @ 34Hz. Crossover point @ 150Hz.
(1) Dayton RS180-4 7" Reference Woofer - 4 ohms - Crossover @ 150Hz - 750Hz.
(1) Dayton RS52AN-8 2" Dome Midrange - 8 ohms - Crossover @ 750Hz - 5000Hz.
(1) Vifa D27TG-35 1" Silk Dome Tweeter - 6 ohms -Crossover @ 5000Hz.
I want to be able to get the best out of these drivers, keeping them far enough away from their lower and upper limits, resosnant peaks and breakup points and stay within the "meat & potatoes" section of each driver. I'm thinking that these crossover points should keep the drivers in line, and prevent any beaming and distorsion, which if I'm not mistaken would maximize the off-axis response and imaging/soundstaging, correct?
I do have a bunch of questions, but I'll only start with a few...
1) Are the crossover point I have chosen proper points to use? Again, I only chose them because I'm trying to keep within the best parts of the drivers selected.
2) Zobel Networks - Should this only be used on the bass drivers or can they/should they be inserted into the path of each driver?
3) Notch Filters - If I stay well enough away from the resonant peaks of the drivers via the crossover points, would I not have to worry about these notch filters?
4) What would be the best way to wire the (4) DC160 woofers together for a nominal 8 ohms, series-parallel or parallel-series? Does it matter? What would the overall output gain be roughly (SPL @ 1w/1m)?
5) What would probably be the best "Orders" for each crossover point?
Please keep in mind, I have never designed or built a crossover in my life, but I have been researching it left and right for the past several weeks now and am understanding more and more of it as I go along.
Thanks in advance for any info you can provide, and I will have more questions to ask, I'm sure.
These are going to be a 4-way design...
My goals are to have a tower capable of full-range reproduction, be able to play to decent volumes (not loud), be able to play pipe organ music with believable bass extension, have good dynamics for pop/rock/jazz/blues, natural midrange, good, open top-end extension and convincing imaging and soundstaging that equals or betters really good bookself speakers.
So far, I think the driver lineup will be: (per tower)
(4) Dayton DC160-8 Woofers - 8 ohms - 2.25cf ported enclosure tuned @ 34Hz. Crossover point @ 150Hz.
(1) Dayton RS180-4 7" Reference Woofer - 4 ohms - Crossover @ 150Hz - 750Hz.
(1) Dayton RS52AN-8 2" Dome Midrange - 8 ohms - Crossover @ 750Hz - 5000Hz.
(1) Vifa D27TG-35 1" Silk Dome Tweeter - 6 ohms -Crossover @ 5000Hz.
I want to be able to get the best out of these drivers, keeping them far enough away from their lower and upper limits, resosnant peaks and breakup points and stay within the "meat & potatoes" section of each driver. I'm thinking that these crossover points should keep the drivers in line, and prevent any beaming and distorsion, which if I'm not mistaken would maximize the off-axis response and imaging/soundstaging, correct?
I do have a bunch of questions, but I'll only start with a few...
1) Are the crossover point I have chosen proper points to use? Again, I only chose them because I'm trying to keep within the best parts of the drivers selected.
2) Zobel Networks - Should this only be used on the bass drivers or can they/should they be inserted into the path of each driver?
3) Notch Filters - If I stay well enough away from the resonant peaks of the drivers via the crossover points, would I not have to worry about these notch filters?
4) What would be the best way to wire the (4) DC160 woofers together for a nominal 8 ohms, series-parallel or parallel-series? Does it matter? What would the overall output gain be roughly (SPL @ 1w/1m)?
5) What would probably be the best "Orders" for each crossover point?
Please keep in mind, I have never designed or built a crossover in my life, but I have been researching it left and right for the past several weeks now and am understanding more and more of it as I go along.
Thanks in advance for any info you can provide, and I will have more questions to ask, I'm sure.
good learning experience...
chops,
I think you may have bitten off more than you can chew (not intended as an insult at all, so please don't take it that way).
What size room.? What amplification? What is your experience building crossovers, and cabinets?
Many times a simple 2nd order cross over can take 2 or 3 or more trys to get "right". I'd suggest a simple 2 way build using some Dayton drivers. Design it, including the box, tuned. Then design a crossover. Then do a search for similar designs on the 'net. Compare yours to others. Parts Express has a DIY design section for loudspeakers.
That way you can have the basis for a good performing system if your cross over doesn't sound "right". Now if doing a 4 way multiply the effort, cost and time by at least 8.
Large multiways are tough to design. The most likely success will be with simpler systems. The best success here (the 4ways) is to build an existing design (or stick with my faves, the single , fullrange types). Check out the Linkwitz Orion for some ideas and see if you can emulate it.
Just my opinion.
good luck
stew
chops,
I think you may have bitten off more than you can chew (not intended as an insult at all, so please don't take it that way).
What size room.? What amplification? What is your experience building crossovers, and cabinets?
Many times a simple 2nd order cross over can take 2 or 3 or more trys to get "right". I'd suggest a simple 2 way build using some Dayton drivers. Design it, including the box, tuned. Then design a crossover. Then do a search for similar designs on the 'net. Compare yours to others. Parts Express has a DIY design section for loudspeakers.
That way you can have the basis for a good performing system if your cross over doesn't sound "right". Now if doing a 4 way multiply the effort, cost and time by at least 8.
Large multiways are tough to design. The most likely success will be with simpler systems. The best success here (the 4ways) is to build an existing design (or stick with my faves, the single , fullrange types). Check out the Linkwitz Orion for some ideas and see if you can emulate it.
Just my opinion.
good luck
stew
Re: good learning experience...
No, I don't think I've bitten off more than I can chew. No offence taken.
My very first successful pair of loudspeakers were 3-way towers I built 11 years ago when I was 21, which I still have and in fact am listening to right now. I did a lot of research on designs at the time and came up with a nice, rugged and heavy enclosure design. It started off with a RatShack 8" woofer, Bose 5.25" mid, Bose 2" cone tweeter with RatShack 3-way xover, and a mini toggle switch on the rear to reverse the polarity of the tweeter 180*, which is quite effective. 7-8 years ago, I upgraded it with a Vifa 8" P21W0-20 woofer, Dynaudio 5.25" mid and Dayton xover @ 375Hz & 3000Hz. It will be further tweaked with upgraded caps, Zobel network and L-pad on Bose tweeter. The woofer has been moved to the 4 ohm tap (Re of Vifa is low @ 5.7 ohms), which has greatly improved the upper bass. The bass section of the cabinet is 2.34cf and tuned to 39Hz. These speakers sound better than a pair of AR towers I have, a pair of Infinity towers my brother has, and a heck of a lot better than a pair of Klipsch RB-75's my other brother has.
I have designed and built many of subwoofers, both home and car audio. My current home sub for my theater uses (2) Dayton 15" DVC drivers in a push-pull fashion in a 6.3cf sealed enclosure, massively braced, powered by a Crown XTi 1000, and gives me solid output down to 12Hz. The tightest, most musical subwoofer I have built, and blows away the SVS PB12-ISD/2 I used to have in every way imaginable.
Also speaking about subs, my fav was and still is the dual 15", twin dipole H-Frame subs I built several years ago. Those were THE BEST sounding subs I have ever heard, ever!
1) 13'x17' room.
2) 100W per/ch @ 8 ohms.
3) I rebuilt the crossovers in my Klipsch Cornwalls, then modified them with a true bandpass, then modded again for a lower tweeter xover point, then modded them again to 2-way and lower xover point for Altec 511B horn and 902-8T drivers, then reverted back to stock spec and completely removed when I moved to full active Rane xover and bi-amping. Also assembling and soldering together a Dayton xover for one of the bookshelf speaker kits for my brother.
4) Have built quite a few different cabinets over the years, including the ones I mentioned above.
Kind of already done this. Review #3 above.
Although I don't have all the money in the world, I have enough (and then some) to take on this project to completion and tweaking. And I have all the time in the world.
The only tough part I really see at the moment is knowing for sure if the xover points I chose will work the way I want and what slopes for the 4 different sections will be best. I'm guessing the xover points will be fine, and probably use a 1st order between the 4 woofers and midwoofer, 2nd order from midwoofer to dome midrange, and 3rd order from dome midrange to tweeter. I'm also guessing the combined output of the 4 woofers will be in the neighborhood of 91dB, which will blend in perfectly with the rest of the drivers, and the tweeter being slightly lower at 90dB, which is what I want.
Also, the 4 Dayton DC160 drivers would be configured in a push/pull fashion (not isobarik), 2 mounted on front baffle, 2 mounted inverted on rear baffle. And the reason for going with 6.5" drivers for bass?... Very fast, tight, accurate and controlled, especially when used in push/pull. Plus these particular drivers in my brother's bookshelf speakers put out tremendous amounts of low bass! I can only imagine what 4 of them in a slightly larger than required enclosure will do, tuned slightly lower.
The reason I want to take on a project like this is because I do not care for bookshelf speakers all that much with thier limits, and for music, I'd rather use full-range towers without the need of a sub. Plus I like a good challenge and something different from everything else out there.
No, I don't think I've bitten off more than I can chew. No offence taken.
My very first successful pair of loudspeakers were 3-way towers I built 11 years ago when I was 21, which I still have and in fact am listening to right now. I did a lot of research on designs at the time and came up with a nice, rugged and heavy enclosure design. It started off with a RatShack 8" woofer, Bose 5.25" mid, Bose 2" cone tweeter with RatShack 3-way xover, and a mini toggle switch on the rear to reverse the polarity of the tweeter 180*, which is quite effective. 7-8 years ago, I upgraded it with a Vifa 8" P21W0-20 woofer, Dynaudio 5.25" mid and Dayton xover @ 375Hz & 3000Hz. It will be further tweaked with upgraded caps, Zobel network and L-pad on Bose tweeter. The woofer has been moved to the 4 ohm tap (Re of Vifa is low @ 5.7 ohms), which has greatly improved the upper bass. The bass section of the cabinet is 2.34cf and tuned to 39Hz. These speakers sound better than a pair of AR towers I have, a pair of Infinity towers my brother has, and a heck of a lot better than a pair of Klipsch RB-75's my other brother has.
I have designed and built many of subwoofers, both home and car audio. My current home sub for my theater uses (2) Dayton 15" DVC drivers in a push-pull fashion in a 6.3cf sealed enclosure, massively braced, powered by a Crown XTi 1000, and gives me solid output down to 12Hz. The tightest, most musical subwoofer I have built, and blows away the SVS PB12-ISD/2 I used to have in every way imaginable.
Also speaking about subs, my fav was and still is the dual 15", twin dipole H-Frame subs I built several years ago. Those were THE BEST sounding subs I have ever heard, ever!
1) 13'x17' room.
2) 100W per/ch @ 8 ohms.
3) I rebuilt the crossovers in my Klipsch Cornwalls, then modified them with a true bandpass, then modded again for a lower tweeter xover point, then modded them again to 2-way and lower xover point for Altec 511B horn and 902-8T drivers, then reverted back to stock spec and completely removed when I moved to full active Rane xover and bi-amping. Also assembling and soldering together a Dayton xover for one of the bookshelf speaker kits for my brother.
4) Have built quite a few different cabinets over the years, including the ones I mentioned above.
Kind of already done this. Review #3 above.
Although I don't have all the money in the world, I have enough (and then some) to take on this project to completion and tweaking. And I have all the time in the world.
The only tough part I really see at the moment is knowing for sure if the xover points I chose will work the way I want and what slopes for the 4 different sections will be best. I'm guessing the xover points will be fine, and probably use a 1st order between the 4 woofers and midwoofer, 2nd order from midwoofer to dome midrange, and 3rd order from dome midrange to tweeter. I'm also guessing the combined output of the 4 woofers will be in the neighborhood of 91dB, which will blend in perfectly with the rest of the drivers, and the tweeter being slightly lower at 90dB, which is what I want.
Also, the 4 Dayton DC160 drivers would be configured in a push/pull fashion (not isobarik), 2 mounted on front baffle, 2 mounted inverted on rear baffle. And the reason for going with 6.5" drivers for bass?... Very fast, tight, accurate and controlled, especially when used in push/pull. Plus these particular drivers in my brother's bookshelf speakers put out tremendous amounts of low bass! I can only imagine what 4 of them in a slightly larger than required enclosure will do, tuned slightly lower.
The reason I want to take on a project like this is because I do not care for bookshelf speakers all that much with thier limits, and for music, I'd rather use full-range towers without the need of a sub. Plus I like a good challenge and something different from everything else out there.
chops: thanks for the info!
Ok, so now we know alot more about you and your capabilities, so I guess now we can bounce ideas instead of trying to convince you what you should or shouldn't build .
Ok, do you have an active Xover, and 4 amps (of almost any type)? Or could you borrow some? then I'd beginn designing the xover by actively amplifying them. That way it will allow you to tweek the slopes, and the frequencies.
Once set, then develop passive Xovers. Inductors for low cut off frequencies are $$$, so this might turn out to be more cost effective.
Even pawn shop intergrated amps would suffice.
Ok, so now we know alot more about you and your capabilities, so I guess now we can bounce ideas instead of trying to convince you what you should or shouldn't build
.Ok, do you have an active Xover, and 4 amps (of almost any type)? Or could you borrow some? then I'd beginn designing the xover by actively amplifying them. That way it will allow you to tweek the slopes, and the frequencies.
Once set, then develop passive Xovers. Inductors for low cut off frequencies are $$$, so this might turn out to be more cost effective.
Even pawn shop intergrated amps would suffice.
Re: chops: thanks for the info!
Oh, don't worry about amps. I have a plethora of amps laying around!
My Rane AC 22B is only a 2-way stereo or 3-way mono, and it unfortunately doesn't allow for different rate slopes. I guess I could test n' tune the top end first and get a circuit built for the tweeter, then use the Rane for the woofers, midwoofer and mid-dome. That's a great idea really. Why didn't I think of that?! LOL
Depending on how big of an inductor is needed for the woofers, I could always go with those Erse Super Q's.
Nanook said:Ok, so now we know alot more about you and your capabilities, so I guess now we can bounce ideas instead of trying to convince you what you should or shouldn't build
Ok, do you have an active Xover, and 4 amps (of almost any type)? Or could you borrow some? then I'd beginn designing the xover by actively amplifying them. That way it will allow you to tweek the slopes, and the frequencies.
Once set, then develop passive Xovers. Inductors for low cut off frequencies are $$$, so this might turn out to be more cost effective.
Even pawn shop intergrated amps would suffice.
Oh, don't worry about amps. I have a plethora of amps laying around!
My Rane AC 22B is only a 2-way stereo or 3-way mono, and it unfortunately doesn't allow for different rate slopes. I guess I could test n' tune the top end first and get a circuit built for the tweeter, then use the Rane for the woofers, midwoofer and mid-dome. That's a great idea really. Why didn't I think of that?! LOL
Depending on how big of an inductor is needed for the woofers, I could always go with those Erse Super Q's.
a page with some info...
look here , a "cookbook" stye Xover page for 3,4, and 5 way xovers
the output of the woofs would be about 91 dB if all four were on the same plane (and sharing the same acoustic enclosure), else 1 pr front, 1 pr back would end up with 88db/1W/1m
2nd orders for the tweet/mid seems good, and for the woofs. just try to keep an octave and a half away from the fs of the drivers. As for the single 7" woof, why?
I looked at using 2 mid/woofs in series(the reference 7") , same mid, same tweet. pretty simple .
Remember too, that the cross overs are reactive and will suck up a lot of energy, and roomgain will saturate the room with bass very quickly.
Back ta Lucile and company..
look here , a "cookbook" stye Xover page for 3,4, and 5 way xovers
the output of the woofs would be about 91 dB if all four were on the same plane (and sharing the same acoustic enclosure), else 1 pr front, 1 pr back would end up with 88db/1W/1m
2nd orders for the tweet/mid seems good, and for the woofs. just try to keep an octave and a half away from the fs of the drivers. As for the single 7" woof, why?
I looked at using 2 mid/woofs in series(the reference 7") , same mid, same tweet. pretty simple .
Remember too, that the cross overs are reactive and will suck up a lot of energy, and roomgain will saturate the room with bass very quickly.
Back ta Lucile and company..
haha... I've already been to that page, since I have TrueRTA. Totoally unrelated, but, the thing that stinks is that I upgraded my computer a while back and am now running Windows XP Pro 64-Bit, and apparently TrueRTA doesn't operate with a 64-bit processor. So now I have a $100 program that I can't even use! I guess I'll have to try it again on my laptop, but it usually inserts too much noise into the readings.
Eventhough all 4 woofers will be in one common chamber, being that 2 of them would be in the back would drop the output down to 88dB? Hmm... Maybe I'll have to have all 4 of them up front, but still have 2 of them inverted. That should get them back up to 91dB.
So you think I should do 2nd order for all drivers, both low and high pass? Any particular reason why? I think I'm keeping more than 1.5 octaves away from any of the drivers Fs with the selected xover points except for the dome-mid. I guess I should bump that xover point up to 850hz.
Why have the single 7" midwoofer in the mix? Well, I was originally planning on building just a 3-way bookshelf system using the same 3 top drivers. Then I decided to build another set of towers instead, pretty much leaving the top drivers as is and adding the 6.5" woofers for the bass section, which those DC160 drivers are very good at reproducing. Plus, that 7" RS180 is a very light aluminum cone (w/ phase plug) and is very good at realistically reproducing lower midrange information. I feel it is a much better match to the aluminum dome-mid driver. That and the fact that I don't want the DC160 drivers extending up to 850Hz to xover to the dome-mid.
Of course the xovers are reactive and will suck up "some" power, but that's the nature of the beast. The nice thing about using these drivers is that there is pleny of documentation on the net about them, measurement charts, graphs, reactions with xovers, etc, etc, so I think from going off all of that, I can probably get these speakers in the ballpark right off the batt. Then all I have to do is listen and tweak.
I'm not really too concerned with roomgain and bass saturation all that much. For whatever reason, either one of the two rooms I would choose to have these speakers in, the strongest roomgain kicks in the sub-40Hz range, and leaves you with very little to no boom at all. Maybe it has somthing to do that both rooms are physically connected via a large 4'Wx8'Hx23'L hallway and both vent in the kitchen which is exactly halfway down the hallway. All I know is that no matter what subwoofer I have ever used, or how many I have used, they have always measured really flat and extended very low in both rooms. Even a pair of Definitive Technology BP10B's I had a couple years ago worked out really good in these rooms and extended easily down to 20Hz, although at a reduced level of course.
Couple random thoughts.....
....Crossovers seem a little close together and a lot of overall in the driver selection. The Classic series 8" seems out of place with the other drivers.
Here is a thought:
WMTMW config. with the RS 7" as the Woofer (sealed), CSS FR125 as the Mid and the Vifa D26NC55 tweeter. I would est. crossover points at 300 for the RS to the CSS and ~ 3k for the CSS to the Vifa.
http://www.planet10-hifi.com/css.html
Each driver should be working in well within their "happy zones". This setup should have F3 around mid-70 Hz for sealed and 40-Hz if the RS are ported.
Another random thought, have the 7" RS ported and put a high-pass filter on the 7" such that the driver never operates below the tuning, has a low-pass filter before the 1st port resonance, Possible?
For the low-bass, have a integral powered sub, say a RSS210HF…
....Crossovers seem a little close together and a lot of overall in the driver selection. The Classic series 8" seems out of place with the other drivers.
Here is a thought:
WMTMW config. with the RS 7" as the Woofer (sealed), CSS FR125 as the Mid and the Vifa D26NC55 tweeter. I would est. crossover points at 300 for the RS to the CSS and ~ 3k for the CSS to the Vifa.
http://www.planet10-hifi.com/css.html
Each driver should be working in well within their "happy zones". This setup should have F3 around mid-70 Hz for sealed and 40-Hz if the RS are ported.
Another random thought, have the 7" RS ported and put a high-pass filter on the 7" such that the driver never operates below the tuning, has a low-pass filter before the 1st port resonance, Possible?
For the low-bass, have a integral powered sub, say a RSS210HF…
The 150Hz Xover point is (relatively) low. Below that frequency the drivers would have a near spherical radiation pattern (of course this will depend of the enclosure shape as well). So mounting the drivers on the back shouldn`t make much difference what concerns efficiency.
I don`t think it would drop by 3db.
Quite the opposite:
4 of the same drivers (be it parallel-seriell oder serial-parallel wired) working 'in-phase' in the same frequency range will have an efficiency boost due to an acoustic effect called "mutual coupling".
Search the forums, You`ll find plenty.
What I think might give trouble is mounting drivers on the backside and that depending of the low-pass slope for the woofers, higher frequency sound radiated from the back could interfere not so nicely with what the mid-bass unit radiates from the front baffle.
IMO, mounting drivers (woofers) on the backside of an enclosure is complicating things unnecessarily without gaining much except maybe some sort of cancellation effect of enclosure vibrations at very low frequencies. I´d do that only for 'real' subwoofers under
about 100Hz with high(er)-slope crossovers.
I wouldn`t do it in this case... and... your intended 4-way speaker project is complicated enough.
If You invert two of the four drivers, You`d get (near) zero acoustical output.....
cocolino said:
This is a very nasty and rough drawing, but this is similar to what I'm thinking at the moment. And when I said inverting 2 woofers, I meant phyically inverting them but keeping them in phase.
In the pic below, the rear woofers would be open to the outside world, just recessed in a little so that the baskets/magnets don't stick out the back of the enclosures. Something else I didn't mention before is that the upper enclosure could be ported as well, at what frequency I don't know, but maybe is better to be left sealed.
Hopefully, this pic will clear a few things up.
An externally hosted image should be here but it was not working when we last tested it.
Oh well, then I misunderstood You, the picture makes it clear now.
Still, it doesn`t make a difference regarding what I said about the "mutual coupling" thing and it needs to be adressed if You`re going passive.
When You`re going active this is not an issue as You can compensate for this much more easily.
Whatever You do, I´d recommend to go active at least for the bass.
It doesn`t cost You more, it`s easier to handle, it`s more flexible and finally I bet the result will be better too.
It could be but I would not do it. I can`t see any advantages in doing this.
Here a rough sketch what I would do:
I`m not familiar with the drivers You use but if You keep the bass-mid enclosure sealed You`ll end up somewhere between 80-100Hz resonance frequency for the 7" bass-mid driver in its enclosure (I´d aim approximately for a system Q=0.7).
When You decide going active You can now high-pass the mid-bass driver with an electronic 12dB crossover at the drivers resonance frequency, which would make for a total of 24dB acoustically (12db driver in enclosure + 12dB electric crossover).
When You low-pass the 4 bass drivers with about the same 24dB slope (experimentation required) You`ll end up with a nice symetrically (acoustic) 24dB crossover.
Due to the slope and the lower Xover frequency (as to what You have planned) for the bass You`d also possibly minimise trouble from the rearwards firing woofers at higher frequencies and furthermore likely would make the speakers less dependend from room positioning (think reflections from the rear walls).
As for the slopes and the final Xover frequencies of the crossover for the rest of the system. I think it will be hard to predict what will be the best solution.
When You`re sure that You want to use this drivers and in this configuration You should just build the thing and then take measurements of the individual drivers "in situ", without any crossover. It will be more clear then what is to do or what You could try first (or next).
BTW:
Another thing to keep in mind is "baffle-step".
Depending on the width of the baffle this will occur somewhere inbetween the frequency range of the mid-bass driver and has to be compensated in the crossover.
How do you figure it doesn't cost more than a passive network?!
I would have to buy more amps and another electronic crossover. I don't know about you, but that would cost a heck of a lot more than going passive.
As far as "this" speaker system is concerned, the entire xover network is going to be passive.
I was thinking about this. If I have the rear woofers recessed into the cabinet as shown in the pic, I would put acoustic padding on all 4 sides of that recess. After I did that, I would attach a cover plate to the rear of the cabinet over the recessed area, also with acoustic padding on it, that would block the rear waves exiting directly behind the drivers, but the sides of the cover plate would have gaps large enough to allow the bass to vent through unrestricted. Think of it as a kind of phase shield like those found on some metal dome tweeters. I think something like that might work to help kill the higher frequencies.
I'm glad you brought this up. I haven't done a whole of studying on this yet. Do you know of any good sites online that go into detail on this? I want to and need to learn more about it.
The woofer setup you drew is a kind of dipole and will cancel out as the frequency goes lower. I don't think you want this? I don't understand what you mean about the plastic cover...
BSC is one of the most basic concepts in speaker design. Pick up Speaker Building 201 for a good primer on design.
Here is a great thread to read, not so much because it uses similar drivers, but for a perspective on the design method of a "pro": http://htguide.com/forum/showthread.php4?t=26574
BSC is one of the most basic concepts in speaker design. Pick up Speaker Building 201 for a good primer on design.
Here is a great thread to read, not so much because it uses similar drivers, but for a perspective on the design method of a "pro": http://htguide.com/forum/showthread.php4?t=26574
As "Nanook" mentioned already, good inductors for low frequency Xovers are expensive and You`d need more than those You finally use in the crossover. A passive 4-way is complex, You need a big parts box to play with.
I`d really advise to reconsider this.
Getting a passive 4-way crossover right isn`t exactly a trivial thing.
I`m convinced that in this case doing the woofer part active, will simplify the contruction of the crossover considerably.
Altough I´m now messing about 25 years with DIY speakers and I have all the equipment one can think of and that could be handy, I wouldn`t want to do a 4-way passive anymore.
I don`t say it can`t be done and the last thing I`d want is to spoil Your fun but my gut feeling tells me that You`ll probably run in much more trouble that You can think of in the moment.
You`ve got quite a big project there. I`d suggest not to hurry too much (very near future project), let sink things in a bit more and collect a few more opinions meanwhile.
Who is talking about buying?
I thought this site is about DIY
Seriously, even if You can`t or don`t want to DIY, for making only the woofer part active all You need is one stereo amp more. The amp for the woofer needn`t to be of the best quality, more power is better in this case.
The active crossover could be a more of a problem though. I don`t know what`s the cost of commercial ones as I never waste a thought about this because I make mine myself.
OTOH an active crossover with op-amps is easy to built. You don`t have to understand much of electronic crossover theory, there are spreadsheets for this which makes things quite easy.
If You want to get Your feets wet, here only one example to begin with (the two links are about the same crossover):
http://www.diyaudio.com/forums/showthread.php?threadid=74420
http://mysite.verizon.net/vze3xvxs/audio/id20.html
It might work but I doubt it. I´d imagine You`d need LOTS of padding to absorb something like 250Hz waves.
Here only two examples:
http://www.t-linespeakers.org/tech/bafflestep/index.html
http://sound.westhost.com/bafflestep.htm
The net is full on this topic, just google for "baffle-step" and You`ll find plenty to read.
Uhhmm no, this isn`t an open baffle construction where low frequencies cancel out. The enclosure prevent this.
When there will something cancel out here, it`s at "higher" frequencies (shorter wavelength) when the waves from the rear firing woofers bounds back from the walls (or bent around the enclosure) and join the directed radiated sound from the front firing woofers.
No it's not an open baffle, but it is a dipole as drawn. The OP says the back of the rear woofers is open. If the woofers are all wired the same polarity then the output from the back of the rear woofers is out of phase with output from the front woofers. Being as these will handle bass duties the outputs will cancel, depending on the length from front to back. I could be wrong but that's how it looks on the drawing.
augerpro said:
It's a push/pull configuration to cancel out even-order harmonic distorsions from the motor, suspension, etc, etc of the woofers. It's the same exact way my DIY subwoofer is in my theater system, which is just like the M&K subs.
The front woofers are wired in phase, the rear woofers out of phase. When the cones on the front baffle move backwards into their baskets into the cabinet, the woofers on the rear baffle move forward out of their baskets, but also into the cabinet. It's really not that complicated.
And if you want to get technical about it, it wouldn't be considered a dipole, it would be considered a bipole if anything.
It´s correct that the woofers would be out of phase if all were wired the same polarity as You assume.
Considering the Xover point of only 150Hz, the acoustical output would be indeed almost zero.
But ...it obviously can`t have been the purpose of this 4 woofer arrangement to get zero out of them.....or can it
Besides this "chops" said....(You probably only overlooked it)
... which, as I understood it, can mean nothing else than that he intended to electrically reverse the polarity of the rear woofers.
P.S. haven´t seen that chops has responded while I was writing so this post is redundant
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