I've heard a couple of requests for shorting rings. I'd like to briefly give a couple of my thoughts, and hear a few of yours. First of all, I am not well versed in loudspeaker design. Most of WBAL is a combination of good networking and dumb luck. I'm learning all I can, and that is part of the fun.
I had the opportunity to compare back to back, a couple of Burro ancestors that had only two difference. One was mostly cosmetic, and the other was a shorting ring/copper pole sleeve. It's a tiny part that fits nicely on my pinky, but it makes an absolutely huge difference in the way the driver behaves. Basically, it eliminates a bunch of distortion, and causes the impedance curve to remain quite flat into the high frequencies. That sounds good, right?
Here is the rub: that rise in impedance, in combination with most amplifiers, helps keep the frequency response flat. Loudspeakers naturally have a rising frequency response above a frequency related to their diameter. Physics can be a bugger. When the impedance limits the power the amplifier puts out roughly in proportion to that rise, you get, for an 8" driver, maybe a 5 db rise on axis. Then, when you listen a little off axis and keep in mind that your room absorbs HF, you can get a pretty flat response out of a single driver.
But, when the impedance stays low, you get maybe a 10db rise on axis. Don't believe me? Check out the FE206E and FE207E response charts. See the difference? Think that is do to the 206's slightly lower Q? Take a look at the Betsy and BetsyK. They have a Q difference much greater than the 206 and 207, yet their rise is nearly identical. As a matter of fact, if you lay the BetsyK's response over the 207's (when measured on the same setup) they are very, very close. When you lay say, the BetsyK's ancestors (with the shorting ring) curve over that of the 206, you get, again, a response that is very, very close.
I can't tolerate the on axis rise of the driver with a shorting ring. In my system, they sound incredibly bright. Searingly bright. Shouty. It ain't a peak, it's a general trend. One of my customers owns another makers 8" driver with a shorting ring, and talks about a notch filter to cure it's ills. But, it isn't a break up mode, it's just 5-6db too much HF.
Folks tend to deal with it by using cabinets that have considerable bass gain, and gain up into the midrange. Some find that sound to be very detailed, and preferable. I also suspect that some shorting ring fans are a little older and have some hearing loss. Don't yell at me, there is nothing wrong with that. I'm 30 and I can only hear to 16K (I grew up on a farm, with shotguns, and went to play in incredibly loud orchestras and big bands). But, don't assume that the top end you like is the top end everybody likes.
If you like that sound, I won't stop you from using such a driver. I encourage everyone to use equipment they like, and I don't judge. I think different folks ears and brains prioritize different things. But for folks that like a reasonably flat in room response, with most cabinets, most rooms, and most amplifiers, if you have an 8" fullranger with a shorting ring, you need a compensation circuit.
That might be a good way to go. Theoretically, you could get lower distortion, and maybe better sound. Most of the customers I've heard from don't want to use any capacitors, inductors and resistors. I don't want customers unhappy with their speakers. But, for those that understand the effects of a shorting ring, not just those who assume it is better, I would consider offering a speaker.
So, who wants one? I would need a few customers to justify having them built. It wouldn't add more than a few bucks to the cost.
Speak up! Let's keep this thread focused on related motor issues though. If you're looking for something else, start a new thread.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
I had the opportunity to compare back to back, a couple of Burro ancestors that had only two difference. One was mostly cosmetic, and the other was a shorting ring/copper pole sleeve. It's a tiny part that fits nicely on my pinky, but it makes an absolutely huge difference in the way the driver behaves. Basically, it eliminates a bunch of distortion, and causes the impedance curve to remain quite flat into the high frequencies. That sounds good, right?
Here is the rub: that rise in impedance, in combination with most amplifiers, helps keep the frequency response flat. Loudspeakers naturally have a rising frequency response above a frequency related to their diameter. Physics can be a bugger. When the impedance limits the power the amplifier puts out roughly in proportion to that rise, you get, for an 8" driver, maybe a 5 db rise on axis. Then, when you listen a little off axis and keep in mind that your room absorbs HF, you can get a pretty flat response out of a single driver.
But, when the impedance stays low, you get maybe a 10db rise on axis. Don't believe me? Check out the FE206E and FE207E response charts. See the difference? Think that is do to the 206's slightly lower Q? Take a look at the Betsy and BetsyK. They have a Q difference much greater than the 206 and 207, yet their rise is nearly identical. As a matter of fact, if you lay the BetsyK's response over the 207's (when measured on the same setup) they are very, very close. When you lay say, the BetsyK's ancestors (with the shorting ring) curve over that of the 206, you get, again, a response that is very, very close.
I can't tolerate the on axis rise of the driver with a shorting ring. In my system, they sound incredibly bright. Searingly bright. Shouty. It ain't a peak, it's a general trend. One of my customers owns another makers 8" driver with a shorting ring, and talks about a notch filter to cure it's ills. But, it isn't a break up mode, it's just 5-6db too much HF.
Folks tend to deal with it by using cabinets that have considerable bass gain, and gain up into the midrange. Some find that sound to be very detailed, and preferable. I also suspect that some shorting ring fans are a little older and have some hearing loss. Don't yell at me, there is nothing wrong with that. I'm 30 and I can only hear to 16K (I grew up on a farm, with shotguns, and went to play in incredibly loud orchestras and big bands). But, don't assume that the top end you like is the top end everybody likes.
If you like that sound, I won't stop you from using such a driver. I encourage everyone to use equipment they like, and I don't judge. I think different folks ears and brains prioritize different things. But for folks that like a reasonably flat in room response, with most cabinets, most rooms, and most amplifiers, if you have an 8" fullranger with a shorting ring, you need a compensation circuit.
That might be a good way to go. Theoretically, you could get lower distortion, and maybe better sound. Most of the customers I've heard from don't want to use any capacitors, inductors and resistors. I don't want customers unhappy with their speakers. But, for those that understand the effects of a shorting ring, not just those who assume it is better, I would consider offering a speaker.
So, who wants one? I would need a few customers to justify having them built. It wouldn't add more than a few bucks to the cost.
Speak up! Let's keep this thread focused on related motor issues though. If you're looking for something else, start a new thread.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
I dont know
Do have any specs on voice coil inductance
Is it any issue at all with such "light" drivers
Better think about underhung
Ups, I did it, sorry
That's why we've all got such short coils, isn't it?
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
The rising response is an issue with 'normal amps' with the shorting sleeve.... The rising impedance emulates this in amps with higher output impedances, though not as dramatically. One can always EQ, if necessary, though some purists don't care for that approach.
The other concern with a loss of magnetic strength doesn't need to be addressed via changing the magnet, you have the option of adding a bucking magnet if your steel isn't saturated.
The other option, which can work for small batch production is plating. I'm betting you could do a thick(ish) layer of copper or silver easily enough on the pole.
The other concern with a loss of magnetic strength doesn't need to be addressed via changing the magnet, you have the option of adding a bucking magnet if your steel isn't saturated.
The other option, which can work for small batch production is plating. I'm betting you could do a thick(ish) layer of copper or silver easily enough on the pole.
Well the pole and top plate are somewhat shorting rings already.
not as efficient as copper or aluminum, but still a solid iron short.
I think the real magic might be in shorting extra turns that might
happen to overhang a given magnetic gap. Front and back, inside
and out.. Nothing but parasitic inductance to be lost here.
not as efficient as copper or aluminum, but still a solid iron short.
I think the real magic might be in shorting extra turns that might
happen to overhang a given magnetic gap. Front and back, inside
and out.. Nothing but parasitic inductance to be lost here.
The copper pole cap is probably the easiest to implement. Less labor than plating, methinks. I don't know if I have access to any VC's that would work for shorting turns. The loss of strength isn't too bad. I can't recall the exact numbers off the top of my head. It might mean a slightly bigger box, but as long as one is building the enclosure with the drivers in mind, it shouldn't be a big deal.
Paul
Paul
Not even close to as efficient, and the only thing the shorting turns does is act as an electromagnetic brake, it does nothing for distortion. Note the effect of lowered Qms on drivers with an un-split aluminum former.
Hi all
Shorting rings actually can/do reduce distortion. The voice-coil current causes fluctuations in the magnetic field, resulting in (mainly) 2'nd harmonic distortion. The induced eddy currents in the shorting ring help counter-act this.
Paul mentioned in another thread experimenting with whizzerless drivers.
Maybe a driver with a shorting ring (to clean up the distortion) but no whizzer (to tame the treble) would be a winner?
Regards - Godfrey
Shorting rings actually can/do reduce distortion. The voice-coil current causes fluctuations in the magnetic field, resulting in (mainly) 2'nd harmonic distortion. The induced eddy currents in the shorting ring help counter-act this.
Paul mentioned in another thread experimenting with whizzerless drivers.
Maybe a driver with a shorting ring (to clean up the distortion) but no whizzer (to tame the treble) would be a winner?
Regards - Godfrey
No one will argue that shorting rings reduce distortion. Funny that you should bring up the Betsy WoW (which I think will be my new acronym for With out Whizzer). I've read and talked to many folks who for some reason or another, want to believe the brightness of 8" fullrangers with a shorting ring is a single troublesome response peak, rather than an overall trend. It can sort of sound like a peak to the untrained ear, and of course, a peak might be a simpler idea to wrap your head around. Sometimes folk blame the whizzer, thinking it is responsible for all that nasty brightness, and then resort to cutting it off. I've seen even seen people endorse the result! But, while there is less treble overall, you've then got even bigger problems to address. The response still rises hard to 7k or so, and still needs shelving of some sort. Except, you also then need a tweeter!
Now, that isn't to say that a whizzerless widebander with a shorting ring doesn't have incredible potential, but you've got to be willing to design and build significant filters as well as add a tweeter.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Now, that isn't to say that a whizzerless widebander with a shorting ring doesn't have incredible potential, but you've got to be willing to design and build significant filters as well as add a tweeter.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
Seas once made drivers with copper plated poleplates, and ditto phase plug
Back then I thought of it like advertising design feature
Now I know it wasnt just that
It does make a real differense
Whether its significant and worth the cost is a different matter
Regarding rising response
Many fullrange drivers seem to be troubled with that, shortrings or not
I would think the absense of baffel step comp is more of an issue, especially with fullrange drivers
You really need drivers with a falling response, which points at less efficient drivers
May be something like coated cones
Back then I thought of it like advertising design feature
Now I know it wasnt just that
It does make a real differense
Whether its significant and worth the cost is a different matter
Regarding rising response
Many fullrange drivers seem to be troubled with that, shortrings or not
I would think the absense of baffel step comp is more of an issue, especially with fullrange drivers
You really need drivers with a falling response, which points at less efficient drivers
May be something like coated cones
Attachments
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It's true that you'll have a rising response with most fullrange drivers. However, it is possible to balance the right amount of rise with the impedance rise and an off axis listening position, netting a more or less flat in-room, in-system response. The problem is when you introduce a shorting ring, you often get too much rise to balance out that way. Then, the only way to approach a flat response is with a large, heavily furnished room and a cabinet that provides gain way into the midrange.
It would be nice to have drivers that provided some BSC (didn't Dan Wiggins do that?), but it would still have to occur at a fixed point. So, you'd be limited to baffles in a certain size range or you'd risk a lump or dip. On the other hand, we don't tend to be that obsessed with perfectly flat in the FR world. It's not as if the BIB's cabinet gain sums perfectly with the baffle step, yet most of us are happy.
You would, for the most part, be looking at higher mass, lower efficiency fullranger. And that brings with it it's own set or tradoffs.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
It would be nice to have drivers that provided some BSC (didn't Dan Wiggins do that?), but it would still have to occur at a fixed point. So, you'd be limited to baffles in a certain size range or you'd risk a lump or dip. On the other hand, we don't tend to be that obsessed with perfectly flat in the FR world. It's not as if the BIB's cabinet gain sums perfectly with the baffle step, yet most of us are happy.
You would, for the most part, be looking at higher mass, lower efficiency fullranger. And that brings with it it's own set or tradoffs.
Paul
Wild Burro Audio Labs - DIY Full Range Speakers
That response rise vs. inductance is an issue that can also go the other way. Current sources deliver more voltage into inductive top ends. This puts the way the rise behaves on a spectrum, from voltage------current sources and more-----less top end with a shorting ring in place.
Really, though, a single shorting ring around the base of an undercut pole goes a long way- it's the symmetricity we're after, more than anything else, we want to kill the Le(Xmax) increase on inward stroke
I know that Im getting back the very old thread into limelight.
Well first of all if shorting rings are not used the eddy currents will pull the coil without free movement. You need to stop that soft friction and now if you observe brightness in highs it means that especially in full range driver then you are hearing it because of the cone breakup becoz now your motor is able to go smoothly to upper frequencies.
Check scanspeak top of the line tweeters all have shorting rings and the response is flat to 20KHz so its not brightness its very smoothly opening up all the frequencies showing up the flaws in the system as well as the cone breakup is very clearly felt.
If felt bright design the crossover in such a way that it will compensate that brightness.
There is a big difference between the brightness and transparency.
Well first of all if shorting rings are not used the eddy currents will pull the coil without free movement. You need to stop that soft friction and now if you observe brightness in highs it means that especially in full range driver then you are hearing it because of the cone breakup becoz now your motor is able to go smoothly to upper frequencies.
Check scanspeak top of the line tweeters all have shorting rings and the response is flat to 20KHz so its not brightness its very smoothly opening up all the frequencies showing up the flaws in the system as well as the cone breakup is very clearly felt.
If felt bright design the crossover in such a way that it will compensate that brightness.
There is a big difference between the brightness and transparency.
I am measuring a few 4-5' mid-/fullrange loudspeakers for usage in high-quality hands-free terminals and see the same picture. The non-LTI distortions stay the same (re main) regardless of signal amplitude, even for very small SPL (AEC adaptive filters pick up everything). The reason for that seems to be an abnormal 3rd harmonic. In mid frequencies, it stays practically the same. Therefore, I can not model drivers with Volterra. In my experience, the constant level of a harmonic can be a result of feedback ... and that's a kind of what shorting ring does.
May anyone confirm or negate that this is the effect of shorting ring?
Attached are
1) residual distortions of 100mm Infinity Reference on Queen's Dust (15s, amplified by 30dB) and
2) 3rd harmonics sweep results for various SPL, 75dBSPL ... 94dBSPL @1m.
May anyone confirm or negate that this is the effect of shorting ring?
Attached are
1) residual distortions of 100mm Infinity Reference on Queen's Dust (15s, amplified by 30dB) and
2) 3rd harmonics sweep results for various SPL, 75dBSPL ... 94dBSPL @1m.
