Here's my problem. For quality, you need good speakers, a good long-term home for them, and then to take the effort to tweet for that permanent location. That model doesn't fit a moving workstation.
Alternatively, you can have as good a speaker as you can devise (such as a great little box or something with a ribbon or even small ESL cell tweeters and with a sub woofer box somewhere, esp on the floor) and plop them down wherever you are working and be happy with what sonic pleasures you get.
If the latter, we aren't really talking about design for your setting as per post 1, just what's a good small speaker or maybe what's a good small speaker for close-range listening.
B.
Alternatively, you can have as good a speaker as you can devise (such as a great little box or something with a ribbon or even small ESL cell tweeters and with a sub woofer box somewhere, esp on the floor) and plop them down wherever you are working and be happy with what sonic pleasures you get.
If the latter, we aren't really talking about design for your setting as per post 1, just what's a good small speaker or maybe what's a good small speaker for close-range listening.
B.
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Yeah, I'm just looking for the latter.
I just want a really good close range speaker and let the sonic dice lie where they may when it comes to room variables.
I have a bad habit of reaching for the stars and I figured a ribbon/planar set-up would be superior to dynamic in just about any situation that can allow it.
But you seem to be implying otherwise?
I just want a really good close range speaker and let the sonic dice lie where they may when it comes to room variables.
I have a bad habit of reaching for the stars and I figured a ribbon/planar set-up would be superior to dynamic in just about any situation that can allow it.
But you seem to be implying otherwise?
I believe you want a full range planer, not a ribbon. About 10 inch wide and maybe 15 inch tall.
Basically a big pr of headphones set out in front of you
Use EQ to taste. Eather passive or active. You will be in near field so directivity not an issue.
You are close enough that big volume not an issue
Use small, maybe 1/4 inch wide by 1/8 inch deep magnets and space them out about 3/8 to 1/2 inch. You can space then at about 1/4 inch and get a bit more sensativity BUT will have a bit more ripple in response due to slot resonance. The wider spacing will tend to have a bit less ripple. Eather way you may need to EQ it out. Space the diaphragm about .06-.08 inch away from mags.
Just a simple flat diaphragm planer. Tension the film to get about a 50 hz resonance ( dont sweat this much just get it tight so it doesnt flap easily)and then ( very important) use thin felt on back side to EQ the bass rise
If you need more bass depth use a small sub. Maybe 6 inch with opposing woofers to cancel vibes ( you dont want the table vibrating into your arms as bass perception might be a broblem). Might have to add mass to cones to go deep.
None of this makes sense for a speaker listened to at a distance BUT up close is a different story.
This is where I would start.
Basically a big pr of headphones set out in front of you
Use EQ to taste. Eather passive or active. You will be in near field so directivity not an issue.
You are close enough that big volume not an issue
Use small, maybe 1/4 inch wide by 1/8 inch deep magnets and space them out about 3/8 to 1/2 inch. You can space then at about 1/4 inch and get a bit more sensativity BUT will have a bit more ripple in response due to slot resonance. The wider spacing will tend to have a bit less ripple. Eather way you may need to EQ it out. Space the diaphragm about .06-.08 inch away from mags.
Just a simple flat diaphragm planer. Tension the film to get about a 50 hz resonance ( dont sweat this much just get it tight so it doesnt flap easily)and then ( very important) use thin felt on back side to EQ the bass rise
If you need more bass depth use a small sub. Maybe 6 inch with opposing woofers to cancel vibes ( you dont want the table vibrating into your arms as bass perception might be a broblem). Might have to add mass to cones to go deep.
None of this makes sense for a speaker listened to at a distance BUT up close is a different story.
This is where I would start.
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You can even use some of the foil traces on the same diaphragm as the tweeter if ya want and make it a two way.
I would build in a way to allow this. Can always reconnect traces for full range if you dont like.
I built one once with two of the foil traces in exact center of diaphragm as the tweeter. A concentric planer. It was good at lower volumes where the diaphragm wasnt moving a lot. Also tryed with tweeter traces at the side sort of the way Maggie does bass - mid.
I would build in a way to allow this. Can always reconnect traces for full range if you dont like.
I built one once with two of the foil traces in exact center of diaphragm as the tweeter. A concentric planer. It was good at lower volumes where the diaphragm wasnt moving a lot. Also tryed with tweeter traces at the side sort of the way Maggie does bass - mid.
more windings = higher resistance AND LOWER sensitivity
if you double the number of "windings" , you increase the resistance by a factor of 4 because to fit more windings in u have to make them smaller in width. So a net loss in sensitivity of about 3 dB. Actually a bit worse than that really due to loss in space between windings
with ribbons and planers a single "winding" is the highest sens and lowest resistance
You are in near field so I would not worry about sensitivity. Just make enough winding and or foil thickness to get needed resistance.
if you double the number of "windings" , you increase the resistance by a factor of 4 because to fit more windings in u have to make them smaller in width. So a net loss in sensitivity of about 3 dB. Actually a bit worse than that really due to loss in space between windings
with ribbons and planers a single "winding" is the highest sens and lowest resistance
You are in near field so I would not worry about sensitivity. Just make enough winding and or foil thickness to get needed resistance.
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Doesn't more windings = more powerful magnetic field and thus better sensitivity?
If more windings = lower sensitivity then maybe a solid metalized sheet would be preferable?
I suppose in such a configuration the magnets would need to be arranged in an ESL type unipolar field on each side.
What's your opinion? Ignoring the impedance factor.
If more windings = lower sensitivity then maybe a solid metalized sheet would be preferable?
I suppose in such a configuration the magnets would need to be arranged in an ESL type unipolar field on each side.
What's your opinion? Ignoring the impedance factor.
BTW I would not try to make it a push pull with magnets on each side. So long as you are listening at very close range as I assume is the idea here? , the diaphragm doesnt have to move much and push pull not necessary( so long as the diaphragm is big)
Besides a push pull will have forces to deal with in building that will be a very serious issue
Likley your biggest problem will be control of diaphragm below about 300 hz. Standing waves down there can kill any bass response in a planer. Magie uses "dots" Apogee uses corrugations , both use diferential tunning and resistance to air flow through magnets etc.
In your case you are close to speaker and likley not as concerned with this issue as you dont need a strong bass rise at resonance to offset the falling response of a dipole. some felt on back side can tame an damp thigs enough to get around the tricky bizz of tuning a planer to do big bass. Just adjust the amount of felt to get a flat response at your ears. And of course if u use a sub then it gets even easyer
Besides a push pull will have forces to deal with in building that will be a very serious issue
Likley your biggest problem will be control of diaphragm below about 300 hz. Standing waves down there can kill any bass response in a planer. Magie uses "dots" Apogee uses corrugations , both use diferential tunning and resistance to air flow through magnets etc.
In your case you are close to speaker and likley not as concerned with this issue as you dont need a strong bass rise at resonance to offset the falling response of a dipole. some felt on back side can tame an damp thigs enough to get around the tricky bizz of tuning a planer to do big bass. Just adjust the amount of felt to get a flat response at your ears. And of course if u use a sub then it gets even easyer
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Only in that it has more resistance to air flow. You can get same by adding felt to single sided design.Actually best to use a tight weave "screen" and attach firmly to magnet structure. Perfectly solid and unmovable is ideal but no such thing but its close enough.
If look at commercial planer woofer you see only about 12% open area! This controls bass resonance and quiets down standing waves a bit between 100-400 hz
Planers have a whimpy motor, not good like a coil in strong magnet gap like cone, so planers need air flow resistance when diaphragm is tension ed to a high Q resonance
The best sounding bass I heard from a planer was one with NO tension. It sounded like a well damped sealed box woofer without the box color, BUT now you have super low sensativity thats basically unusable. It needs to be a very big diaphragm to work well.
push pull has magnetic flux lines that are more flat across the flat foil traces on diaphragm , SO they have lower distortion
However if you spread your magnets out about 2-3 times as far as typical designs AND put diaphragm really close to magnets, then the flux lines of a single sided magnet design are good enough. This of course will be lower sensitivity and lower peak volume capability BUT if your sitting only a foot or two away as I assume you will be then thats ok
If look at commercial planer woofer you see only about 12% open area! This controls bass resonance and quiets down standing waves a bit between 100-400 hz
Planers have a whimpy motor, not good like a coil in strong magnet gap like cone, so planers need air flow resistance when diaphragm is tension ed to a high Q resonance
The best sounding bass I heard from a planer was one with NO tension. It sounded like a well damped sealed box woofer without the box color, BUT now you have super low sensativity thats basically unusable. It needs to be a very big diaphragm to work well.
push pull has magnetic flux lines that are more flat across the flat foil traces on diaphragm , SO they have lower distortion
However if you spread your magnets out about 2-3 times as far as typical designs AND put diaphragm really close to magnets, then the flux lines of a single sided magnet design are good enough. This of course will be lower sensitivity and lower peak volume capability BUT if your sitting only a foot or two away as I assume you will be then thats ok
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Unlike electrostatics, the force generated by current carrying conductors placed in a magnetic field is orthogonal to the field direction, not parallel to it. So if the magnetic field was oriented front-to-back, current thru a ribbon conductor oriented top-to-bottom in the gap would generate a sideways force…and not much music.
Pictorial description of forces in magnetic planar posted here: I always wanted to ask...why Bias voltage on ESL?
Unfortunately no. Unlike dynamic drivers, the coupling between the acoustic/mechanical domain and the electrical domain is pretty weak. Any easy way to see this is to try and find the impedance peak at resonance…it is nearly non-existent even with push-pull planars. As an example, even diaphragm resonance with a 10-15dB peak results in barely perceptible wrinkle in Magnepan impedance. The only method left to add damping is with acoustic means, using felt or woven acoustic mesh as Lowmass has recommended.
Attachments
The force on the diaphragm scales with the B*L product, where B is the magnetic flux density, and L is the length of the conductor immersed in the magnetic field and carrying the music signal. The number of windings matters only to the extent that it affects L and the driver’s impedance (which determines how much current it draws and how happy your amplifier will be).
I found that by selecting thin aluminum, adjusting the width of traces, and running the traces through the magnetic field multiple times, I could get the impedance up to an acceptable level (4 - 8 ohms) without resorting to a transformer. I also increased L and therefore the sensitivity.
As Bolserst pointed out, the physics behind a planar magnetic driver is different than that of an ESL. The electric field between large parallel ESL stators is constant, and therefore generates a constant driving force (assuming the charge on the diaphragm isn’t allowed to move). It is widely assumed that devising a push-pull magnet system will have the same effect in a planar magnetic system but that is incorrect. Two “sheets” of spaced magnets, brought close to each other to duplicate the ESL stator arrangement, does not automatically yield a similarly uniform (in this case magnetic) field. The magnetic field lines tend to follow quite complicated paths between opposite poles in both the push-pull and single-sided arrangements. It is therefore up to the designer to decide whether the extra expense of many more NdFeB magnets, and the much more complicated structure required to deal with the forces between opposing sheets of magnets, yield benefits that justify the problems they introduce. I opted for a single-sided magnetic structure and am glad I did.
One nice feature of the nearfield listening arrangement you’re considering is that you can justifiably pay less attention to the effect of the room, and the directivity of the speakers. I find that when I’m listening carefully, my head is in the sweet spot anyway, and my ears are much closer to the speakers than to the walls or other large surfaces (other than the desktop) so the off-axis behavior is less important. I made the speakers tall, with the bottom of their radiating area close to the desktop so that the reflection off that surface would effectively extend the height of the speaker. Unfortunately, I ended up undermining that approach a bit when I tilted the panels back instead of keeping them vertical. While listening I don’t find the tilt to be a big problem.
I don’t think the assumption that ribbons, which are sometimes called “pure” but I think should be called “simple,” are inherently superior to planar magnetic drivers. There are excellent and poor examples of both breeds, and I’m not even sure the best of one type are consistently better than the best of the other.
I think you should forge ahead with your desktop dream!
Few
Danny Richie has a new project, with ribbon:
Closed speaker, without bass-reflex.
-3 dB: 75 Hz. About 89 dB/W/m.
New Studio Monitor
An externally hosted image should be here but it was not working when we last tested it.
