Jussi said:
I'm just saying that the design itself I think has more potential..
1. no acoustic resistance near driver (..which might work with the cardoid.. don't know what your plans are here.)
2. more limited range for the mid (lower excursion, less distortion, no need to worry about baffle step comp., etc.)
3. better segregation between bass region and sub-bass (allows for a subwoofer with lower distortion)
with the exception of #1 - most of it has nothing specifically to do with cardoid vs. dipole operation.
Scott,
1. What's wrong with acoustic resistance?
2. Better limited yes but harder to find a driver for that range. Not that much BSC but much more dipole cancellation and EQ. 90dB efficienct 7" driver is about 75dB efficient at 300Hz. Poor.
3. Yep. Subwoofer is one of my perversions. I've tried few commercial combinations and never got them working without input limitations (works with one album, doesn't with other) but it sure is a intresting challange in the future. Call it desire to bang head to the wall etc. 😉
Jussi
1. What's wrong with acoustic resistance?
2. Better limited yes but harder to find a driver for that range. Not that much BSC but much more dipole cancellation and EQ. 90dB efficienct 7" driver is about 75dB efficient at 300Hz. Poor.
3. Yep. Subwoofer is one of my perversions. I've tried few commercial combinations and never got them working without input limitations (works with one album, doesn't with other) but it sure is a intresting challange in the future. Call it desire to bang head to the wall etc. 😉
Jussi
I also had an idea of this rather large 4-way configuration. Separated woofercolums with WMTMW mains (see attachment), mids in totally open environment (just circles in the air) and upper bass drivers in their small baffles. It just gets way too large and complicated. Height is also a problem, very tough to get such system physically stable while kids are around...
Jussi
Jussi
Attachments
A bit shame how narrow band that midrange would be. In fully open dipole structure 7" drivers performance is limited to 300-400Hz at bottom end because lack of efficiency and they just can't play that much over 2Khz at the top. At least many metal cone drivers like W18EX would be almost a waste driving 350-2K or so.
Unfortunately there are not so many good midrange drivers around. Most manufacturers are concentrated to midwoofer production, AT and Excels just as examples.
In dipole cone should be at least that 7", perhaps even more. Smaller driver has lower sensitivity and with smaller cone dipole cancellation and EQ requirements are even greater.
Jussi
Unfortunately there are not so many good midrange drivers around. Most manufacturers are concentrated to midwoofer production, AT and Excels just as examples.
In dipole cone should be at least that 7", perhaps even more. Smaller driver has lower sensitivity and with smaller cone dipole cancellation and EQ requirements are even greater.
Jussi
Pasi,
Intresting to explain this issue to you in English but I'd give it a try...
This fully open midrange idea isn't 100% proof. I have some doubts it's transient behavior and like mensioned efficiency drops dramatically. But in theory it doesn't have any possibly co-radiating surface around it and polar response should be as close to dipole as it can with a dynamic driver. But it's a two blade sword. Seas Hexadym motors would propably be best option but they lack efficiency. High eff drivers have huge motors, propably stuffed basket construction and so on.
I have those MTM acoustic resistance prototypes ready and I'll propably give them a try. Higher WAF option as well.
Jussi
Intresting to explain this issue to you in English but I'd give it a try...
This fully open midrange idea isn't 100% proof. I have some doubts it's transient behavior and like mensioned efficiency drops dramatically. But in theory it doesn't have any possibly co-radiating surface around it and polar response should be as close to dipole as it can with a dynamic driver. But it's a two blade sword. Seas Hexadym motors would propably be best option but they lack efficiency. High eff drivers have huge motors, propably stuffed basket construction and so on.
I have those MTM acoustic resistance prototypes ready and I'll propably give them a try. Higher WAF option as well.
Jussi
Pasi,
Basically I'm not so comfortable to drop this WWMT full dipole plan away from my near future constructions. I have used pretty considerable amount of time to draw that damn thing and it has rather many small details that suit my present perversions. No need to dress them as features since I can't proove their strengths.
Overally plan is pretty ready. I have those Scan Speak woofers for upperbass duty, I like to hammer my head against the wall while trying to get subwoofer integrated and operational and I guess those Dynaudio tweeters I have could serve treble.
But midrange is a problem. Custom AT Flex unit can have 94dB efficiency with 4 ohm coil and +-3mm overhung motor. Further more they could deliver mids with very low loss suspension which combined with strong motor suits my vision of precise midrange. With some potential flipsides of cource.
Naturally I could use acoustic resistance with the midrange but 7" mid in AR cabinet can easily extend downt to 200Hz which makes 25W woofers unadequate for their task. I could use heavier woofers and that changes the whole construction.
Ideas?
Jussi
Basically I'm not so comfortable to drop this WWMT full dipole plan away from my near future constructions. I have used pretty considerable amount of time to draw that damn thing and it has rather many small details that suit my present perversions. No need to dress them as features since I can't proove their strengths.
Overally plan is pretty ready. I have those Scan Speak woofers for upperbass duty, I like to hammer my head against the wall while trying to get subwoofer integrated and operational and I guess those Dynaudio tweeters I have could serve treble.
But midrange is a problem. Custom AT Flex unit can have 94dB efficiency with 4 ohm coil and +-3mm overhung motor. Further more they could deliver mids with very low loss suspension which combined with strong motor suits my vision of precise midrange. With some potential flipsides of cource.
Naturally I could use acoustic resistance with the midrange but 7" mid in AR cabinet can easily extend downt to 200Hz which makes 25W woofers unadequate for their task. I could use heavier woofers and that changes the whole construction.
Ideas?
Jussi
Jussi said:
Nothing per se, rather acoutic resistance coupling to the driver (i.e. stuffing near the driver) tends to "suck the life out of the driver" (..or effects decay unnaturally).
Jussi,
Yes. For me it will be much easier to use one northern language instead, but maybe i will try some words more in english..
No doubt that you have investigated things quite thoroughly. This fully open dipole thing however pays my attention because your "colleague" (designer of these "saddly named" towers, you know..)
mentioned when he visited to listen my Orions that maybe too narrow baffled dipole is bad for transients as you mentioned also. I understood that he supposed so when he compared Orions to narrower baffle dipoples that he has investigated.
Yes. For me it will be much easier to use one northern language instead, but maybe i will try some words more in english..
No doubt that you have investigated things quite thoroughly. This fully open dipole thing however pays my attention because your "colleague" (designer of these "saddly named" towers, you know..)
mentioned when he visited to listen my Orions that maybe too narrow baffled dipole is bad for transients as you mentioned also. I understood that he supposed so when he compared Orions to narrower baffle dipoples that he has investigated.
Pasi,
Know the project and we had a thought to investigate this thing together someday. According to mr Gradient this lack of transients is just a room acoustic mather and I guess he knows considering the construction of their 1.x series.
Shame there are not that many 7" size pure midrange drivers around. Most manufacturers just concentrate to produce midwoofers for 2-ways which leads to extended bass reproduction and lack of efficiency. Top end isn't that great either and xmax capacity is way too much for a mid.
Audio Technology could serve my needs in this aspect but I don't know facts about them. Sure they are praised units but from some psychotic reason I'd like to know why. Scan Speak new sliced paper drivers are also very praised and at least one 15W driver from that range absolutely sucks in THD measurement.
Pigs in a pretty bag. Shame AT doesn't support my thought to invest the drivers and still have a return card on them if they don't serve well in simple serie of measurements.
Naturally there is a backdoor for AR cabinet if fully open dipolemid truely has issues that aren't caused by the room and are more than subjective problems.
In terms of new invested material and less all over again designing this would be the easiest solution. Best? Propably not but its nice to have a thick skin in your forehead, right? 😉
At least Scan Speak - Audio Technology - Dynaudio combination might be "musical" combination over few other technically brilliant options. Unfortunately this term "musical" has suffered some inflation cause of one priest messing around at one domestic forum about this issue.
Jussi
Know the project and we had a thought to investigate this thing together someday. According to mr Gradient this lack of transients is just a room acoustic mather and I guess he knows considering the construction of their 1.x series.
Shame there are not that many 7" size pure midrange drivers around. Most manufacturers just concentrate to produce midwoofers for 2-ways which leads to extended bass reproduction and lack of efficiency. Top end isn't that great either and xmax capacity is way too much for a mid.
Audio Technology could serve my needs in this aspect but I don't know facts about them. Sure they are praised units but from some psychotic reason I'd like to know why. Scan Speak new sliced paper drivers are also very praised and at least one 15W driver from that range absolutely sucks in THD measurement.
Pigs in a pretty bag. Shame AT doesn't support my thought to invest the drivers and still have a return card on them if they don't serve well in simple serie of measurements.
Naturally there is a backdoor for AR cabinet if fully open dipolemid truely has issues that aren't caused by the room and are more than subjective problems.
In terms of new invested material and less all over again designing this would be the easiest solution. Best? Propably not but its nice to have a thick skin in your forehead, right? 😉
At least Scan Speak - Audio Technology - Dynaudio combination might be "musical" combination over few other technically brilliant options. Unfortunately this term "musical" has suffered some inflation cause of one priest messing around at one domestic forum about this issue.
Jussi
Pasi,
To this transient lacking is pretty difficult issue. It can be caused by the room while dipole rear radiation gets its bounce from frontwall. But I guess in that case all dipole systems have similar problems at some frequency where they behave as real dipoles. And if they don't have sharp trancient attack does it make it less accurate? How much gutt effect normal trancients in live music have? And which one is more correct, does dipole have some impulse response problems like we this issue handeled or is dipole just more cabinet resonance free and that way less punchy?
And for example with 7" midrange there are no real need to produce whole midrange with dipolar radiation. Adding some damping material behind the mid I guess it's avoidable to collide to these problems. So radiation pattern would change from dipole to dipoles front radiation only over certain frequencyrange. With 7" mid this would be approximately 1200Hz to mid-treble crossover frequency. The point where midrange cone takes over direcitivity from dipole behavior I don't see that much use for that rear radiation so it can be damped off the equation. This should also even and smooth energy response as well since transition from dipolar mid to cardioid tweeter isn't so sudden.
One issue is also bass. 25W pair can't play that much deep bass. It drops off about 6dB or 50% from Orion and Gradient Revolutions mean SPL capability. So at least those would need a subwoofer below 40-60Hz or so.
That WMTMW also crossed my mind but like mensioned, I didn't got those potential physical stability issues solved and it would also be very low WAF construction so I think I'll pass that. Shame, would have some very intresting aspects where for example our fellow DIY builder is digging into right now.
Jussi
To this transient lacking is pretty difficult issue. It can be caused by the room while dipole rear radiation gets its bounce from frontwall. But I guess in that case all dipole systems have similar problems at some frequency where they behave as real dipoles. And if they don't have sharp trancient attack does it make it less accurate? How much gutt effect normal trancients in live music have? And which one is more correct, does dipole have some impulse response problems like we this issue handeled or is dipole just more cabinet resonance free and that way less punchy?
And for example with 7" midrange there are no real need to produce whole midrange with dipolar radiation. Adding some damping material behind the mid I guess it's avoidable to collide to these problems. So radiation pattern would change from dipole to dipoles front radiation only over certain frequencyrange. With 7" mid this would be approximately 1200Hz to mid-treble crossover frequency. The point where midrange cone takes over direcitivity from dipole behavior I don't see that much use for that rear radiation so it can be damped off the equation. This should also even and smooth energy response as well since transition from dipolar mid to cardioid tweeter isn't so sudden.
One issue is also bass. 25W pair can't play that much deep bass. It drops off about 6dB or 50% from Orion and Gradient Revolutions mean SPL capability. So at least those would need a subwoofer below 40-60Hz or so.
That WMTMW also crossed my mind but like mensioned, I didn't got those potential physical stability issues solved and it would also be very low WAF construction so I think I'll pass that. Shame, would have some very intresting aspects where for example our fellow DIY builder is digging into right now.
Jussi
Jussi said:
the transient (quick changes in spl) is strictly a function of the driver and the excursion required.. those excels are not exactly "snappy" drivers. the increased excursion (by increasing their lower freq. limit), doesn't help matters. Most Hi-Fi drivers suffer this problem, despite often having better THD. specs.. (..its a shame people get so caught up in THD, for the most part conventional levels are innocuous. IMD however is DEFINITLY something to look at.)
rear in-phase reflections can create tonal problems and accentuate a particular freq. - ESPECIALLy if the rear of the speaker is "aimed" into a room corner.
the feeling of "punch" (60-120 Hz) and "slam" (30-50 Hz) often occurs at an "event", however it isn't something that is on the recording to any great degree. (..and its usually severly compressed.) In this respect a dipole is often more accurate to the source while being less accurate to the "event". You can change this to some extent with higher Bl drivers and/or utilizing two drivers in a normal acoustic suspension cabinet with different sealed-off compartments for the rear reverse-phase (i.e. front driver with its rear output enclosed in enclosure #1, rear driver reversed in phase with its "rear" output enclosed in enclosure #2). The problem with the acoustic suspension technique is that it re-introduces the problems that a normal diple gets rid of (..namely compression and back-emf).
Jussi,
This "lack of bunch" (=you do not_feel_bass) of dipoles is very clearly noticeable compared to boxwoofer but for me it is difficult to say wich one is more near real thing..
But (my experience is very limited though) i can not think to go back to box woofers in my room and my taste. Ok, maybe i am also too lazy to investigate best placement of speakers but my room has some quite difficult room modes that seems to be much easier to partly "solve" with dipoles.
When moving towards midrange, things can be more complex and i have not noticed any dramatical difference compared dipolemid to some box or cardioid mids i have heard.
About woofers. Would even Peerless XXLS be more suitable to your application than 25W:s?
This "lack of bunch" (=you do not_feel_bass) of dipoles is very clearly noticeable compared to boxwoofer but for me it is difficult to say wich one is more near real thing..
But (my experience is very limited though) i can not think to go back to box woofers in my room and my taste. Ok, maybe i am also too lazy to investigate best placement of speakers but my room has some quite difficult room modes that seems to be much easier to partly "solve" with dipoles.
When moving towards midrange, things can be more complex and i have not noticed any dramatical difference compared dipolemid to some box or cardioid mids i have heard.
About woofers. Would even Peerless XXLS be more suitable to your application than 25W:s?
The point was lack of snap in midrange. And this in totally open driver versus driver in some size dipole baffle. But like mensioned, no hard evidence, at least not yet. It's very propable that the problem is in room acoustics or related to one persons personal preference of "snap".
Scott,
It's also depending on acoustic design. With same driver closed cabinet and dipole have very different impression of transient. Which one is correct? Propably neither. Some like feel in your skin snap, others consider this tiring.
Pasi,
I've considered XXLS series. Would make me draw that bottom part of the system all over again since driver dimensions are so far apart. But since woofers need to reach pretty high to assist midrange there can't be that much deep bass at the same time. And personally I'd like to make a compromisse in the bass end since it can be assisted later with subwoofer (and which is propably better solution below 40Hz than dipole) than compromisse integration in midrange. I thought to even try something else than steep 4th order slope between woof and mid. 1st order is out while no electrical highpass on a dipole midrange is bit a bad idea. Maybe its ok in Beethoven style system where whole main speaker is highpassed a bit lower.
Jussi
Scott,
It's also depending on acoustic design. With same driver closed cabinet and dipole have very different impression of transient. Which one is correct? Propably neither. Some like feel in your skin snap, others consider this tiring.
Pasi,
I've considered XXLS series. Would make me draw that bottom part of the system all over again since driver dimensions are so far apart. But since woofers need to reach pretty high to assist midrange there can't be that much deep bass at the same time. And personally I'd like to make a compromisse in the bass end since it can be assisted later with subwoofer (and which is propably better solution below 40Hz than dipole) than compromisse integration in midrange. I thought to even try something else than steep 4th order slope between woof and mid. 1st order is out while no electrical highpass on a dipole midrange is bit a bad idea. Maybe its ok in Beethoven style system where whole main speaker is highpassed a bit lower.
Jussi
One possibility is to draw this thing all over with similar idea. Maybe slam 2x12" XXLS to the front, have a small H-frame hidden in the structure (already have an old idea how to make it) and use normal MT with acoustic resistance midrange and waveguided tweeter for the top. Bit like Gradient Revolution but since bass cabinet doesn't need to turn H-baffle is possible obtaining some more capacity. Steep crosses, 150-250Hz and something around 1,8-3Khz. Well naturally upper cross can be gentle if mid-treble unit allows it.
Using AR midrange with 25W isn't that great idea. Nice midwoofer playing 150-250Hz up leaves pretty narrow band for 25W and since they aren't exactly high displacement drivers bass capacity is also modest. And using higher cross, maybe with gentle slope, doesn't leave that much advantage for AR cabinet since plain damping material behind dipole mid can reduce rear radiation when midrange cone gets directive.
I assume 2x12" XXLS doesn't need that much subwoofers to assist anymore. At least not in this modest size room and with music material.
Jussi
Using AR midrange with 25W isn't that great idea. Nice midwoofer playing 150-250Hz up leaves pretty narrow band for 25W and since they aren't exactly high displacement drivers bass capacity is also modest. And using higher cross, maybe with gentle slope, doesn't leave that much advantage for AR cabinet since plain damping material behind dipole mid can reduce rear radiation when midrange cone gets directive.
I assume 2x12" XXLS doesn't need that much subwoofers to assist anymore. At least not in this modest size room and with music material.
Jussi
On the other hand this discussions topic has some advantages as well. I have nothing against normal MT construction but having to all directions leaking AR cabinet combined with High WAF rating it's pretty tough equation.
HQ tweeter and 7" midwoofer in compact "2-way" MT monitor as mains. Midrange in AR cabinet. No need to find drivers with huge efficiency and the whole thing is pretty simple. Bass, below 150Hz or so, to separated dipolewoofers. I've asked around and seems like RCF L18P401 would be a nice solution for this. Sounds like a overkill having stereo 18" woofers but it isn't that much in dipole. Actually in free space they are pretty much as strong as Orions or Revolutions bass when it comes to raw SPL capacity. Separated woofers have propably higher WAF (can be disguised as flowertable etc) and only things clearly visual are small 2-way mains. Nothing that really jumps on peoples face while entering room.
Separated woofers can also be turned to different angles and move a bit to find best tonal accuracy and least room mode problems and all this without messing up mains normal listening triangle. Mains MT structure would also be very safe from bass frequency vibrations since they are meter apart.
Flipsides and flipsides... 😉
Jussi
HQ tweeter and 7" midwoofer in compact "2-way" MT monitor as mains. Midrange in AR cabinet. No need to find drivers with huge efficiency and the whole thing is pretty simple. Bass, below 150Hz or so, to separated dipolewoofers. I've asked around and seems like RCF L18P401 would be a nice solution for this. Sounds like a overkill having stereo 18" woofers but it isn't that much in dipole. Actually in free space they are pretty much as strong as Orions or Revolutions bass when it comes to raw SPL capacity. Separated woofers have propably higher WAF (can be disguised as flowertable etc) and only things clearly visual are small 2-way mains. Nothing that really jumps on peoples face while entering room.
Separated woofers can also be turned to different angles and move a bit to find best tonal accuracy and least room mode problems and all this without messing up mains normal listening triangle. Mains MT structure would also be very safe from bass frequency vibrations since they are meter apart.
Flipsides and flipsides... 😉
Jussi
Jussi,
This is joke.
Somebody, do not remember who (maybe you?), has said that perfectionism + loudspeaker design = early death
😉
😉
Happy new year to everyone in diy-audio !
This is joke.
Somebody, do not remember who (maybe you?), has said that perfectionism + loudspeaker design = early death
😉
😉
Happy new year to everyone in diy-audio !
Member
Joined 2003
Scott,
How near is near? Can you point me to any recommended reading in this area?
Thanks
Jussi,
Do you have a description or drawings of how you might implement the cardioid mid?
Paul
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