It is not quite the same as your original configuration, but have you considered doing it the way I've shown in the attached diagram?
The speakers are electrically out of phase, but mechanically IN phase, meaning when they move, they move in the same physical direction as in they both move north, then the both move south.
It's just a thought.
Steve/bluewizard
The speakers are electrically out of phase, but mechanically IN phase, meaning when they move, they move in the same physical direction as in they both move north, then the both move south.
It's just a thought.
Steve/bluewizard
An externally hosted image should be here but it was not working when we last tested it.
Hey Bluewiz,
I have considered that idea which is push/push design and would give better bass response,not same with even order canceling though.
When I start on bass cabinet first will try push/pull,maybe even try placing driver under enclosure like M&K do with their subwoofers.
I'm not to keen on exposed drivers but will see how it works,if not may end up with your advice.
Also,this is very much an experiment/hobby for me and if I did purchase 604's before I would've modded them,making better cabinets,crossovers ect...
Cheers,
Steven.
I have considered that idea which is push/push design and would give better bass response,not same with even order canceling though.
When I start on bass cabinet first will try push/pull,maybe even try placing driver under enclosure like M&K do with their subwoofers.
I'm not to keen on exposed drivers but will see how it works,if not may end up with your advice.
Also,this is very much an experiment/hobby for me and if I did purchase 604's before I would've modded them,making better cabinets,crossovers ect...
Cheers,
Steven.
I'm, as usual, going off on my own tangent. But hopefully it will generate some worthwhile and relevant information.
To the group in general, this idea of Push/Pull woofers makes sense for a sealed cabinet, but I'm wondering if it can be applied to a bass reflex cabinets, and what considerations would need to be made?
In either sealed example, mine or Doobie's, one woofer is re-enforcing the other, and, more or less, maintaining stable air compliance inside the cabinet.
When one woofer tries to compress the air inside the cabinet, the other woofer is counteracting that by trying to rarefy the air in the cabinet.
By my interpretation, this should make the woofers very sensitive and require less electrical input to make them move.
But, what if there is a Bass reflex port, is that counteracting of compression and rarefication, more or less, nullified, or do we still get the push/pull effect?
Next, seal cabinets are typified by a somewhat high and gradual roll-off on the low end. Does this Push/Pull arrangement lower the -3db point and does it effect the roll-off rate and location?
Finally, which is better from a low frequency perspective, two front facing woofer in a seal cabinet wire in phase, or two woofers on opposite sides of the cabinet in a push/pull arrangement? Assuming of course, all other factors being equal.
Perhaps 'better' is not the right word, I'm probably asking for the advantages and disadvantages of each configuration.
A little knowledge is a good thing, though, admittedly, it can be dangerous.
Just curious.
PS: to Doobie/Steven,
...both are designs are doing exactly the same thing. They are both Push/Pull, but in my case, both speakers are inside the cabinet.
If you completely control your environment, then having a speaker hanging outside the cabinet may not be such a bad thing. Though, you might want to give some consideration to balance and center of gravity.
However, if you are inclined to throw parties, or to move the speakers from place to place, then there is a certain hazard as well as inconvenience to having that speaker hang on the outside.
Steve/bluewizard
To the group in general, this idea of Push/Pull woofers makes sense for a sealed cabinet, but I'm wondering if it can be applied to a bass reflex cabinets, and what considerations would need to be made?
In either sealed example, mine or Doobie's, one woofer is re-enforcing the other, and, more or less, maintaining stable air compliance inside the cabinet.
When one woofer tries to compress the air inside the cabinet, the other woofer is counteracting that by trying to rarefy the air in the cabinet.
By my interpretation, this should make the woofers very sensitive and require less electrical input to make them move.
But, what if there is a Bass reflex port, is that counteracting of compression and rarefication, more or less, nullified, or do we still get the push/pull effect?
Next, seal cabinets are typified by a somewhat high and gradual roll-off on the low end. Does this Push/Pull arrangement lower the -3db point and does it effect the roll-off rate and location?
Finally, which is better from a low frequency perspective, two front facing woofer in a seal cabinet wire in phase, or two woofers on opposite sides of the cabinet in a push/pull arrangement? Assuming of course, all other factors being equal.
Perhaps 'better' is not the right word, I'm probably asking for the advantages and disadvantages of each configuration.
A little knowledge is a good thing, though, admittedly, it can be dangerous.
Just curious.
PS: to Doobie/Steven,
...both are designs are doing exactly the same thing. They are both Push/Pull, but in my case, both speakers are inside the cabinet.
If you completely control your environment, then having a speaker hanging outside the cabinet may not be such a bad thing. Though, you might want to give some consideration to balance and center of gravity.
However, if you are inclined to throw parties, or to move the speakers from place to place, then there is a certain hazard as well as inconvenience to having that speaker hang on the outside.
Steve/bluewizard
This is getting interesting.
The idea of push pull drivers as depicted in both variations begins looking like an open baffle driver.
As Steve explained, the push/pull would maintain a constant pressure in the cabinet, i.e. cancel out the effect of the volume's compliance as a spring loading the woofers.
I think that this design would not result in significant low frequency response as the output from both LF drivers would cancel each other out.
The idea of push pull drivers as depicted in both variations begins looking like an open baffle driver.
As Steve explained, the push/pull would maintain a constant pressure in the cabinet, i.e. cancel out the effect of the volume's compliance as a spring loading the woofers.
I think that this design would not result in significant low frequency response as the output from both LF drivers would cancel each other out.
Hi Steve/Bluewizard,
I've add link that goes into little detail about push/pull design.
http://www.diyaudio.com/forums/showthread.php?threadid=107910
To be clear,my proposed design is out of phase push/pull.
It is generally accepted that design you provided is not true push/pull but variant of one,more akin to bi-pole,where drivers are acoustically in phase as compared to acoustically out of phase drivers,with not the same even order harmonic canceling characteristic effects.
The out of phase approach has many benefits acting as instant real time machanical servo instead of electrical accelerometer with active ic controller within amplifier for correction.Inverted driver has greater control due to more frontal surface cm2 area.Driver transient response increases nearly 2x fold and is equivelent to smaller driver in speed and detail.
Also,there is increase in sensitivity with your suggested design of +3db approx because drivers are more linear working as active passive drive like bi-pole,though both designs are still considered as complimented single drivers in spl power.
These speakers will be used mainly for personal music/home theatre listening,not big on parties.
I think design does compensate for center of gravity and driver uses lighter neodymium magnet than standard.
Will be trying ways to mount rear driver on inside baffle for less driver exposure or even try underneath,but agree your design suggestion is much more tidier.
Cheers,
Steven.
I've add link that goes into little detail about push/pull design.
http://www.diyaudio.com/forums/showthread.php?threadid=107910
To be clear,my proposed design is out of phase push/pull.
It is generally accepted that design you provided is not true push/pull but variant of one,more akin to bi-pole,where drivers are acoustically in phase as compared to acoustically out of phase drivers,with not the same even order harmonic canceling characteristic effects.
The out of phase approach has many benefits acting as instant real time machanical servo instead of electrical accelerometer with active ic controller within amplifier for correction.Inverted driver has greater control due to more frontal surface cm2 area.Driver transient response increases nearly 2x fold and is equivelent to smaller driver in speed and detail.
Also,there is increase in sensitivity with your suggested design of +3db approx because drivers are more linear working as active passive drive like bi-pole,though both designs are still considered as complimented single drivers in spl power.
These speakers will be used mainly for personal music/home theatre listening,not big on parties.
I think design does compensate for center of gravity and driver uses lighter neodymium magnet than standard.
Will be trying ways to mount rear driver on inside baffle for less driver exposure or even try underneath,but agree your design suggestion is much more tidier.
Cheers,
Steven.
Steven,
Of course your drivers are electrically in-phase, because they are both facing in the same direction, but the underlying principle is the same.
With your design, when the front speaker moves forward and tries to rarefy the air in the cabinet (create something of a vacuum) the back speaker moves forward and tries to compress the air if the cabinet by the same amount. This keeps the compliance of the air in the cabinet very stable.
In my design, exactly the same thing happens, but because my bottom woofer is pointing the wrong direction, relative to yours, it must be wired backward.
But in operation, everything happens exactly the same way. When the front speaker moves forward (north) and tries to rarefy the air in the cabinet, the bottom speaker also move in the same direction (north) and counteracts the rarefication with compression.
The only difference is the placement of the speakers. Yours are directly in line, and that may provide some small advantage. But in both designs, when one speakers is pulling on the air, the other speakers is pushing on it.
Neither design strikes me as a design to be used in a tight space like the average living room. However, in a larger room with a reasonable space behind the speaker, this seems like a very intriguing and appealing design.
Considering all the odd designs I see out there, I'm surprised this one isn't used more often.
- - - - - - - - - - - - - - - - - - -
Back to my previous questions, if anyone knows the answers; it seems that this only works in a closed cabinet, is that right? I mean you certainly can build a bass reflex cabinet of this design, but would it work? Would you actually get the advantages of the push/pull effect?
Next, in a standard sealed cabinet, I assume the roll-off starts early and falls slowly because, at low frequencies, the speakers are fighting the tension of the air in the cabinet. There is a limit to the speakers ability to create a vacuum or rarefy the air in the cabinets. In short, there is just too much spring-tension in the cabinet air to allow the speaker to move properly.
With the push/pull design, the 'spring tension of the air' is gone. So as frequencies go lower, there shouldn't be any resistance to the speaker movement from the tension of the air in the cabinet. This then implies, I speculate, that the speaker could respond lower. Its -3db cut-off point should move down.
Am I on the right track?
Steve/bluewizard
Of course your drivers are electrically in-phase, because they are both facing in the same direction, but the underlying principle is the same.
With your design, when the front speaker moves forward and tries to rarefy the air in the cabinet (create something of a vacuum) the back speaker moves forward and tries to compress the air if the cabinet by the same amount. This keeps the compliance of the air in the cabinet very stable.
In my design, exactly the same thing happens, but because my bottom woofer is pointing the wrong direction, relative to yours, it must be wired backward.
But in operation, everything happens exactly the same way. When the front speaker moves forward (north) and tries to rarefy the air in the cabinet, the bottom speaker also move in the same direction (north) and counteracts the rarefication with compression.
The only difference is the placement of the speakers. Yours are directly in line, and that may provide some small advantage. But in both designs, when one speakers is pulling on the air, the other speakers is pushing on it.
Neither design strikes me as a design to be used in a tight space like the average living room. However, in a larger room with a reasonable space behind the speaker, this seems like a very intriguing and appealing design.
Considering all the odd designs I see out there, I'm surprised this one isn't used more often.
- - - - - - - - - - - - - - - - - - -
Back to my previous questions, if anyone knows the answers; it seems that this only works in a closed cabinet, is that right? I mean you certainly can build a bass reflex cabinet of this design, but would it work? Would you actually get the advantages of the push/pull effect?
Next, in a standard sealed cabinet, I assume the roll-off starts early and falls slowly because, at low frequencies, the speakers are fighting the tension of the air in the cabinet. There is a limit to the speakers ability to create a vacuum or rarefy the air in the cabinets. In short, there is just too much spring-tension in the cabinet air to allow the speaker to move properly.
With the push/pull design, the 'spring tension of the air' is gone. So as frequencies go lower, there shouldn't be any resistance to the speaker movement from the tension of the air in the cabinet. This then implies, I speculate, that the speaker could respond lower. Its -3db cut-off point should move down.
Am I on the right track?
Steve/bluewizard
Hi Steve/Bluewizard,
Respectfully,I think that we have misunderstanding between our two design approaches.
I understand that if drivers are traveling in same direction there is even air compliance.
This is not case with implementation I'm seeking.
The arrangement in my design,front driver is firing forward electrically in phase with rear driver firing backwards 180 degrees electrically out of phase at a given time.
It wouldn't make sense to have a driver inverted with both drivers traveling together when same goal could be achieved,as in your suggested design,except for more frontal surface area,being much tidier.
I have used,what I considered "push/push" approach,in many home theatre and car audio sub applications,but never considered them as true "push/pull".
My understanding is that "push/push" uses rear wave as spring with same air compliance moved,where "push/pull" completely cancels rear wave instantly creating constant forced air pressure,both being very good but different in desired effect.
I added picture of difference between our design and another link that describes both a little.
http://www.djsociety.org/Speaker_1.htm
Cheers,
Steven
Respectfully,I think that we have misunderstanding between our two design approaches.
I understand that if drivers are traveling in same direction there is even air compliance.
This is not case with implementation I'm seeking.
The arrangement in my design,front driver is firing forward electrically in phase with rear driver firing backwards 180 degrees electrically out of phase at a given time.
It wouldn't make sense to have a driver inverted with both drivers traveling together when same goal could be achieved,as in your suggested design,except for more frontal surface area,being much tidier.
I have used,what I considered "push/push" approach,in many home theatre and car audio sub applications,but never considered them as true "push/pull".
My understanding is that "push/push" uses rear wave as spring with same air compliance moved,where "push/pull" completely cancels rear wave instantly creating constant forced air pressure,both being very good but different in desired effect.
I added picture of difference between our design and another link that describes both a little.
http://www.djsociety.org/Speaker_1.htm
Cheers,
Steven
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