33102
From: mikeported, [border0.tekotago.ac.nz]
Subject: °°°Types of Distortions °°°
|
hello we had that discussion on distortion,but i want more its easy to find general ideas,but harder to find exact details especialy on the net 1-in push pull,woofers cancel their own 2nd harmonic distortion.. if so,what is going on in the spring mass system to cause this in ths first place! -frequency doubling occurs on woodwind instruments also when u dont play it properly lol- 2-what sort of distortion do the magnet circuits cause/? harmonic structures/ or random noise 3-what sort do the actual cones make/? not much until they flex/? 4-when operated below Fs,speakers generally exhibit 'frequency doubling' is this simply the result of a floppy suspension ..whats going on here 5-why do speakers seem to 'bungy' really far when u drive the amp too hard,theres no reason for it to go REALY excessive excursion,or is this simply me playing too low sinewaves-is it because of the damping factor changing,or something -and why does my jbl have such high quality it doesnt sound bad when tuned below Fs.saying its 'higher quality' isnt enough detail for me. cya! :^) |
Responses:
[33105] [33259] [33260] [33261] [33271] [33275] [33296] [33142] [33169] [33188] [33203] [33144] [33145] [33123] [33124] [33108] [33122]
33105
From: Adrian Mack, [dialup-196-157.wasp.net.au]
Subject: Re: °°°Types of Distortions °°°
URL: My website, Peerless XLS 12 Dual PR Sub Project, 18LW1400 vented sub, Horns, etc.....
|
Hi Mike! > 1-in push pull,woofers cancel their own 2nd > harmonic distortion.. Push-pull configuration will reduce second order hamonics, but it would not cancel them completely. This happens in situations where the two drivers have their cones directly coupled and are wired out of phase. They produce the same distortion, but out of phase to each other and results in it being "cancelled" and hence a reduction of even order harmonic distortion. Odd ordered harmonics will always be added though. > 2-what sort of distortion do the magnet circuits > cause/? harmonic structures/ or random noise Are you referring to the magnetic structure? Or basically the motor? This is the prime contributor of distortion. Gap and pole piece geometries and flow of magnetic flux, materials used, cooling arrangements, voice coil windings and a lot of other things are all factors in this regard. > 3-what sort do the actual cones make/? not much > until they flex/? Thats it, cone flex is the issue here. Other than that theres no issue to deal with. > 4-when operated below Fs,speakers generally > exhibit 'frequency doubling' is this simply the > result of a floppy suspension I've found that on all drivers, distortion rises as they near their mechanical resonance region. This is primarily a result from the magnetic structure, and not the suspension or the diaphram. > 5-why do speakers seem to 'bungy' really far when u > drive the amp too hard,theres no reason for it to > go REALY excessive excursion,or is this simply me > playing too low sinewaves-is it because of the > damping factor changing,or something I dont know what you mean by "bungy", but on your ported 2226H sub, and in all ported systems, excursion rises dramatically below resonance. At frequencies below Fb, the woofer and port are moving togethor so that the woofer goes out when the ports air mass goes in. This results in complete cancellation and the system is unloaded and excursion is increased dramatically. As freqeuncies move through Fl and to Fb, the two resonators are moving towards providing an in-phase signal where they are "pushing against one another" and excursion begins to reduce again. By "bungy" and your words "driving the amp too hard", you might be referring to clipping, which will sound like a hard and harsh distortion of a high frequency, and increases in volume each time the volume knob is turned up more. > -and why does my jbl have such high quality it > doesnt sound bad when tuned below Fs.saying > its 'higher quality' isnt enough detail for me. Exactly. You've choosen an EBS alignment for this driver, and by definition they produce more distortion as they are thrown in a larger than optimal box and also tuned lower than optimal (below resonance). You've limited distortion by merit of motor quality using Professional Series JBL parts, and this driver works better with lower distortion and tighter cone control in EBS enclosures than most commercial drivers do. See "JBL's Tech Note 8" for more information on the 2226H and its distortion reduction methods. We've been through this all before Mike when we had a discussion on driver selection for your new EBS subwoofer and the reasons for choosing this driver. But I hope I've shed some new light on this issue anyway. Take care! Adrian |
Responses:
[33259] [33260] [33261] [33271] [33275] [33296] [33142] [33169] [33188] [33203] [33144] [33145] [33123] [33124] [33108] [33122]
33259
From: Brian, [206.48.63.223]
Subject: Re: °°°Types of Distortions °°°
|
>I've found that on all drivers, distortion rises as >they near their mechanical resonance region. This is >primarily a result from the magnetic structure, and >not the suspension or the diaphram. I somewhat agree here. With all drivers, the more excursion the driver is asked to perform, the more distortion you can expect to get. For example, consider a free-air (or infinite-baffle) system. If power input is kept the same while the input frequency drops, the driver's cone will undergo increased excursion. With that increased excursion comes increased distortion. This distortion can be caused by a nonlinear motor, and/or a nonlinear spider/surround combination. Now, let's put that driver in an acoustic suspension alignment. With this type of alignment, the air in the box exerts greater control over the driver's excursion than the driver's spider/suspension. Distortion due to these factors might therefore decrease. However, distortion due to a non-linear motor will not. As a result, generally speaking you can expect distortion caused by the the suspension to form a greater part of the overall distortion as the alignment approaches an infinite-baffle type of configuration (e.g. free-air, very large box, or even vented systems below Fb). |
33260
From: Adrian Mack, [dialup-196-172.wasp.net.au]
Subject: Mechanical resonance of speakers
URL: My website, Peerless XLS 12 Dual PR Sub Project, 18LW1400 vented sub, Horns, etc.....
|
Hi Brian! > For example, consider a free-air (or infinite- > baffle) system. If power input is kept the same > while the input frequency drops, the driver's cone > will undergo increased excursion. With that > increased excursion comes increased distortion. Exactly. And in systems where excursion is reduced, which is best handled in vented systems, distortion is reduced also. And the point about Acoustic Suspension and IB systems and overring, also applies too, and a reduction in overring is a reduction in harmonic distortion too. But since the biggest culprit in this region is magnetic and not mechanical, I'm not sure how much shift is done to distortion figures in that area. I am sure that overall distortion is reduced, however, and that's a good thing. A cabinet built around Davies implementaion of the Thiele/Small works or a PiAligned cabinet will yield even greater results and less overring than the two aforementioned cabinets. But the magnetic structure does play a major part in distortion, and poor drivers typcially having really loose suspensions (high Qms) will simply "ring all day long" once you hit them with a few short bursts at resonance, no matter what cabinet we put them in in attempt to damp the driver. Data published by JBL and others attributes this to a concern primarily from the magnetic structure, and not the suspension or diaphram. But just look at the distortion graphs of any woofer, and you'll notice that from about a half octave above resonance, distortion rises dramatically. Certain motors have actually been designed to operate the driver below resonance, so it may be that distortion drops here again. But it is a common trend that I've not seen an exception for - That woofers peak distortion is in the resonance region. Adrian |
33261
From: Brian, [206-48-63-223.caribsurf.com]
Subject: Re: Mechanical resonance of speakers
|
>But the magnetic structure does play a major part in >distortion, and poor drivers typcially having really >loose suspensions (high Qms) will simply "ring all >day long" once you hit them with a few short bursts >at resonance, no matter what cabinet we put them in >in attempt to damp the driver. I think once an amplifier is connected to that system, (or the voice coil is shorted out) its response will be primarily determined by Qes, not Qms. This can be readily verified: take any speaker, disconnect the amplifier from the terminals, then tap on the cone. You may hear a boingy sound, and the speaker's cone will visibly ring -the higher the Qms, the more boingy the sound and the longer the ring. That's because Qms dominates when there are no connections to the speaker's terminals. Now, short the terminals with a piece of cable and tap on the cone again. The boingy sound should disappear immediately and the speaker will cease to ring (unless its Qes is also high, of course). Qes now dominates. The conclusion that can be drawn here is that the effect of Qms on the system's frequency response can typically be ignored once its several orders of magnitude greater than Qes. >Data published by JBL and others attributes this to a >concern primarily from the magnetic structure, and >not the suspension or diaphram. Perhaps, but if JBL is referring to a weak magnetic structure that's not exerting sufficient control over the cone, this suggests that it is Qes is the issue, not Qms - the weaker the motor, the higher the Qes of the driver. Obviously though, the higher the Qms, the greater the problem as Qes itself increases (Qts will approach Qms). >But just look at the distortion graphs of any woofer, >and you'll notice that from about a half octave above >resonance, distortion rises dramatically I'm not surprised - excursion rises dramatically as frequency decreases. The rate of increase will depend on the driver's Qts (the higher the Qts, the greater the increase). |
33271
From: Adrian Mack, [dialup-196-193.wasp.net.au]
Subject: Re: Mechanical resonance of speakers
URL: My website, Peerless XLS 12 Dual PR Sub Project, 18LW1400 vented sub, Horns, etc.....
|
Hi Brian! > I think once an amplifier is connected to that > system, (or the voice coil is shorted out) its > response will be primarily determined by Qes, not > Qms. I think I didn't explain myself well, what I was trying to say is motors with real high Qms tend to sound really "muddy". Thats not to say all motors with high Qms sound bad though. These sorts of "bad" motors are ones that have Qms that is way high, in attempt to tune the woofer very low. This is done to encourage maximum bass extension and motor strength is necessarily weakest. And the magnet is likely to be made of what is probably a cheap non-homogenous ceramic "cake" and an ineffective and non-symmetrical magnet geometry. It is overall just a poor performer, and sounds real bad. Often though, they'll have very low resistance and the value of Qes is "shunted" across the mechanical Qms, which is much higher. Qts is then made relatively low by virtue of the low Qes shunted across what is a fairly high Qms. In this case it needs motor braking in the extreme. But with motors with very high Qms, say 20, they are just real bad, and could be desribed as a "mudmotor". Even the example above, is not a driver I would like - and it has poor filter characteristics, the way the driver has been designed too, is poor, and is not a good performer. Distortion is in the triple digits on a device like this. > I think once an amplifier is connected to that > system, (or the voice coil is shorted out) its > response will be primarily determined by Qes, not > Qms. Again, thats not exactly what I was arguing, but being connected to the system - the motors filter characteristics dont change, and these high Qms mudmotors still perform badly. > Now, short the terminals with a piece of cable and > tap on the cone again. The boingy sound should > disappear immediately and the speaker will cease to > ring (unless its Qes is also high, of course). Qes > now dominates. Thats right. Shorting the terminals is like having an amplifier with infinite damping factor, and it should control the cone. But thats not to say Qms is not relevant, because it is - what we have in this situation with the shorted terminals, is what would look like extremely low output impedance of the amplifier - but of course, theres no amplifier there, its just a wire shorting the terminals which also has very low resistance. Output impedance is inversely proportional to damping factor, and it highly affects Qes. Shorting the terminals essentially provides infinite motor braking to the driver. Increasing magnet strength, by more magnet, or more coil, also affects Qes. Of course though, it needs to be connected to the system for it to operate! But you've made a good point though, and motor braking is typical of drivers having high Q and low resonant. And these sorts of "mudmotors" typically have distortion over 100 percent. But we cannot say that Qms is not relevant, because it describes a large part of how the driver is damped and what we can expect of these kinds of drivers, often showing how manufactures cut costs in attempt to maximize bass extension - but throw away just about everything else, to put it loosely. > Perhaps, but if JBL is referring to a weak magnetic > structure that's not exerting sufficient control > over the cone, this suggests that it is Qes is the > issue, not Qms - the weaker the motor, the higher > the Qes of the driver. Obviously though, the higher > the Qms, the greater the problem as Qes itself > increases (Qts will approach Qms). Total Q and the figures that make it up, Qes and Qms, are not the only factors of distortion. Having a perfectly symmetrical magnet field, underhung voice coils, voice coil windings, magnet material, flow of magnetic flux, magnetic geometries, copper shorting rings, cooling techniques, and more, all are contributors to distortion, and all primarily arise from the magnetic structure. > I'm not surprised - excursion rises dramatically as > frequency decreases. The rate of increase will > depend on the driver's Qts (the higher the Qts, the > greater the increase). The increase in distortion is not just due to an increase in excursion, rather, the entire magnetic structure is responsible for this. This area is what I call the "critical resonance region", and distortion rises as a function of frequency here. You'll also notice that at the upper cutoff of the driver where response starts to drop again - distortion rises too, partly due to breakup modes. But the distortion at resonance is a much bigger concern. All drivers exhibit least distortion midband. Adrian |
33275
From: Brian, [206-48-63-223.caribsurf.com]
Subject: Re: Mechanical resonance of speakers
|
>These sorts of "bad" motors are ones that have Qms >that is way high, in attempt to tune the woofer very >low. This is done to encourage maximum bass extension >and motor strength is necessarily weakest. From the time you start to mention motor strength, you're talking about Qes, not Qms. >Often though, they'll have very low resistance and >the value of Qes is "shunted" across the mechanical >Qms, which is much higher. Qts is then made >relatively low by virtue of the low Qes shunted >across what is a fairly high Qms. In this case it >needs motor braking in the extreme. Which is exactly what will be happening if Qes is low. There is a direct correlation between Qes and the ability of the motor to stop and start cone motion - the lower the Qes, the greater this ability. Therefore, in this case the output characteristics of the driver are primarily dependent on Qes. >But with motors with very high Qms, say 20, they are >just real bad, and could be desribed as a "mudmotor". I haven't come across any drivers with Qms that high. The highest I've seen is Qms=12. In any case, you're likely to find that, even with those drivers, performance is more affected by Qes, which is usually an order of magnitude smaller than Qms. >What we have in this situation with the shorted >terminals, is what would look like extremely low >output impedance of the amplifier - but of course, >theres no amplifier there, its just a wire shorting >the terminals which also has very low resistance. If you repeat the test, this time instead of using a cable, you use an amplifier that's turned on but no input signal, you'll get a similar response to the tap test. Good amplifiers have high damping factors (30 and above is typically the case). We can even work out an estimate of the amplifier's DF on the Qes of the amplifier/speaker system: Qes' = Qes * (1 + 1/DF) For example, a driver with Qes of 0.30 connected to an amplifier with a DF of 30 (at the driver's rated impedance) will result in a system with Qes = 0.30 *(1+ 1/30) = 0.31. >Shorting the terminals essentially provides infinite >motor braking to the driver. Nope. The motor braking won't be infinite - it's dependent on the driver's Qes :-). >But you've made a good point though, and motor >braking is typical of drivers having high Q and low >resonant. Motor braking is typical of all drivers. The ability of a driver's motor to control the motion of the cone is reflected in Qes. The greater the ability, the lower the Qes figure. >But we cannot say that Qms is not relevant, because >it describes a large part of how the driver is damped ...only if there's nothing connected to the driver. Once we connect an amplifier (or anything else across the driver's coils), Qes dominates, unless of course Qes approaches Qms in value (in the vast majority of drivers, there's an order of magnitude of difference between the two). There's one factor that Qms does affect significantly - the driver's impedance response. The greater the Qms, the high the impedance peak at resonance. As for how this would affect the driver's frequency response or distortion characteristics, I'm not sure. >Total Q and the figures that make it up, Qes and Qms, >are not the only factors of distortion. Having a >perfectly symmetrical magnet field, underhung voice >coils, voice coil windings, magnet material, flow of >magnetic flux, magnetic geometries, copper shorting >rings, cooling techniques, and more, all are >contributors to distortion, and all primarily arise >from the magnetic structure No argument there. |
Responses:
[33296]
33296
From: Adrian Mack, [dialup-196-228.wasp.net.au]
Subject: Re: Mechanical resonance of speakers
URL: My website, Peerless XLS 12 Dual PR Sub Project, 18LW1400 vented sub, Horns, etc.....
|
Hi Brian! > From the time you start to mention motor strength, > you're talking about Qes, not Qms. Motor strength is relevant to Qms and Qes. > Which is exactly what will be happening if Qes is > low. There is a direct correlation between Qes and > the ability of the motor to stop and start cone > motion - the lower the Qes, the greater this > ability. Therefore, in this case the output > characteristics of the driver are primarily > dependent on Qes. Yes, thats motor braking. But I've already described the significance of Qms. From about 10 to 12, is about when the cones getting pretty loose, and distortion and harmonics in these types of devices is typically much higher than others. From about 20, it just gets real bad. I've not overlooked Qes at all - in fact, I've used that on a number of occasions, and stated drivers that absoluetely require an amp thats a good current sink/source, and also, others when its "less needed". Qms describes mechanical damping and motor strength and cone weight are relevant to this, and Qes is the ratio of series motor circuit resistance to the square of BL, or basically electrical damping. The main purpose of this was originally distortion - and I described how high mechanical Q speakers typically have much higher harmonics and ringing because of the way they are built. But on this side-discussion thats branched out, both Qms and Qes tell the story of the motors filter characteristics. > I haven't come across any drivers with Qms that > high. The highest I've seen is Qms=12. In any case, > you're likely to find that, even with those > drivers, performance is more affected by Qes, which > is usually an order of magnitude smaller than Qms. I agree, theres little drivers with Qms of 20, but Parts Express do have some when I was flicking through their catalogue. These "mudmotors" I talk about absolutely require motor braking, and I described high Qms speakers having very low DC resistance and a requirement of an amplifier with good damping factor - but these still have triple digit distortion figures, and thats a real bad thing. So these ones will be worse, even once taking advantage of motor braking. But not all manufactures do this, and some will make both Qms and Qes very high, and therefore Qts too, and these motors just plain suck, lots of overring. One look at Qms - and the motor with Qms of 12, probably has a lot greater control over the cone at resonance than one with a Qms of 20. But these devices still "arn't as good". You've overlooked the important of Qms in my last post, and how the driver is constructed. > Nope. The motor braking won't be infinite - it's > dependent on the driver's Qes :-). Yes, but the wire is just about infinite damping - DC resistance and BL still has the ability to change Qes. Just because the cone seems stiff when we tap it with the terminals shorted - you see the effect of motor damping, but you dont know how much system performance is affected. Sure, electrical damping does play a major part in how the driver is damped - my argument is that high Qms speakers have a poor design to realize maximum bass extension, and the driver is not balanced for anything else, and have high distortion at resonance and high harmonics too. You know the ones I'm talking about - you've seen them, and you've probably avoided them too, and we've all joked about it. Its the one you hear blaring from that kids racing car down the street, with the really crap sound system installed. They just go to Wal-Mart and buy a 50 dollar woofer and stick it in one of those wedge-shaped pre-made boxes. Then the trunk lid rattles and they think it's cool. So getting back to the main argument; the magnetic structure is the prime contributor to distortion. These high Qms mudmotors typically are built very poor to realize maximum bass extension which necessitates poor motor contol, an on devices like this, it's the case that they've cut costs in attempt to tune the woofer very low, and thats the reason they have to tune their woofers this way. And on poor motors like these often they'll use really crap non-symmetrical cheap magnets and these drivers are the ones with triple digit distortion. It all comes back down to how the manufacture decides to "spend his money". That doesn't mean all high Qms speakers are mudmotors, but all these "mudmotors" I've seen - typically sound real bad, and typically, most designed this way are. Theres much more 80Hz and 120Hz and such harmonics being generated from speakers like this, and thats distortion which we can avoid - using better parts. Adrian |
Responses:
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33142
From: Richard Greene, [frasier.ford.com]
Subject: JBL 2226 is not intended to be a subwoofer driver
|
That's a very efficient pro woofer with an FS of 40Hz. which is about an octave too high and and XMAX of only 7.62mm which is about half of what you should look for. The 15" Adire Audio Tempest driver I use with an FS of 19Hz. and DUMAX of 16.4mm would be a much better choice for a subwoofer driver. It would easily outperform the JBL 2226 and only costs $150. I'd guess the 2226 price is at least triple that amount. I strongly doubt that JBL's product literature recommends the 2226 for use as a home subwoofer driver. The low distortion specs for the JBL have been misinterpreted -- they only apply to 100Hz. to 500Hz. which are well above subwoofer frequencies. Distortion at under 50Hz. is probably much higher (although output under 30Hz. is likely to be weak unless boosted a lot by cabin gain). Very few people could hear subwoofer harmonic distortion under 5% while listening to music -- often 10% distortion is required before most people would notice. That's one reason subwoofer maximum output tests often use a 10% harmonic distortion limit. Paying a lot more money for a pro woofer to reduce already inaudable harmonic distortion by a few percentage points may please the owner of the driver, but is probably not an audible improvement. reducing harmonic distortion bhear v |
33169
From: mikeported, [proxy.ia2.marketscore.com]
Subject: shiva vs 2226
URL: jbl2226h
|
which is about an octave too high and and XMAX of only 7.62mm which is about half of what you should look for excuse me,but i know what i want,not you 7.6mm is heaps for a 15inch ,you are thinking of 15mm on a shiva which is 12inch The low distortion specs for the JBL have been misinterpreted -- they only apply to 100Hz. to 500Hz. which are well above subwoofer frequencies. Distortion at under 50Hz. is probably much higher probably,perhaps not. still lower than a shiva/adire audio cheepies. the 'almighty subwoofer' 2226g tuned to 24hz has 2.5%THD at 110db spl,so my 33hz tuning will certainly have better or similar specs/. i do not want 2nd and 3rd order harmonics appearing in music that wasnt here> im going basshorn soon. it was my choice-shiva or 2226h 2nd hand. i chose 2226h for quality and efficiency ,those are what made me get it instead of a shiva which would require 350watt rms to make decent spl. + i dont need 21hz from a 12inch speaker which will need high excursion to do it anyway. |
33188
From: Brian, [206-48-63-219.caribsurf.com]
Subject: Re: shiva vs 2226
|
>7.6mm is heaps for a 15inch ,you are thinking of 15mm >on a shiva which is 12inch 7.6mm is still low for a 15 inch subwoofer driver these days. The Adire Audio Tempest driver is a 15" driver, and its Xmax is similar to that of the Shiva (which is approx double that of the JBL driver). Doubling Xmax nets you a theoretical 6dB increase in peak SPL output. However, your amplifier must be able to provide enough power to take advantage of the larger Xmax, and the driver itself should be able to handle the higher power. >the 'almighty subwoofer' 2226g tuned to 24hz has >2.5%THD at 110db spl,so my 33hz tuning will certainly >have better or similar specs/. Way too many variables here to make such an assumption. For example, if you use a port that's 1" in diameter, I'll bet you'll get a lot more than 2.5% THD @ 110dB :-). >i chose 2226h for quality and efficiency ,those are >what made me get it instead of a shiva which would >require 350watt rms to make decent spl. Remember: the greater the efficiency of a driver, the larger the box size requirements, or the higher the cutoff frequency of the alignment. |
Responses:
[33203]
33203
From: Adrian Mack, [dialup-196-64.wasp.net.au]
Subject: EBS 2226 vs distortion
URL: My website, Peerless XLS 12 Dual PR Sub Project, 18LW1400 vented sub, Horns, etc.....
|
Hi Brian! > 7.6mm is still low for a 15 inch subwoofer driver > these days. The Adire Audio Tempest driver is a 15" > driver, and its Xmax is similar to that of the > Shiva (which is approx double that of the JBL > driver). Doubling Xmax nets you a theoretical 6dB > increase in peak SPL output. Before we continue, the 2226H is not intended as a subwoofer by JBL. But there is merit in using this in an EBS design as Mike has. They are really excellant drivers. But your right, in comparison, Tempest certainly has more excursion than 2226H. But that does not make it a better driver, and there is just too many other things to consider. And drivers with huge excursions are usually ones that are tuned very low, and efficiency of the driver is decreased. The 2226H is tuned a little higher, but is a much more efficient driver. An EBS 2226H in 175L and 33Hz tuned cabinet, with the negative slope of it compensated to achieve a flat response from 33Hz and up, it is capable of 118db using 300W, and is still within its linear excursion limits of 7.6mm. They arn't really suited to subwoofer applications due to their relativily high Fs and low Qms, so a person can certainly find a woofer that runs lower. They're not likely to find that generates less distortion, however. Even at 20Hz, the 2226 rises to 10% THD which is better than what most woofer generate. At 50Hz, its 1% THD. At 30Hz, I cant exactly remember, but off the top of my head, it rises to 3% THD at this point. This in mind, an EBS 2226 in the enclosure Mike is using it in is an attractive way to extend the low frequency response of his sytem. His sacrificed below 30Hz extension, but his retained very low distortion. I dont think anyone would be disgusted by JBL Professional Series parts by any standards, because they really are great parts. > Remember: the greater the efficiency of a driver, > the larger the box size requirements, or the higher > the cutoff frequency of the alignment. Thats right, and EBS 2226 Mike has is 175L, which is pretty big. In itself, increasing magnet strength will increase the resonant frequency and also efficiency as you've pointed out. But its possible to have low-resonant high efficiency motors still. JBL's done an excellant job on balancing motor strength and cone weight to achieve a true 20Hz motor with 95db 1w/1m sensitivity, the 2245H. The 2235H is also tuned in a similar way and is a high efficiency 20Hz motor too. Adrian |
Responses:
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33144
From: Adrian Mack, [dialup-196-113.wasp.net.au]
Subject: Re: JBL 2226 is not intended to be a subwoofer driver
URL: My website, Peerless XLS 12 Dual PR Sub Project, 18LW1400 vented sub, Horns, etc.....
|
Hi Richard! Your right, and Tempest is a better choice for 20Hz bass. And its also not intended as a subwoofer either. Or an even better choice would be the JBL Professional Series 2235H and 2245H which are both 20Hz woofers. > The low distortion specs for the JBL have been > misinterpreted -- they only apply to 100Hz. to > 500Hz. which are well above subwoofer frequencies. > Distortion at under 50Hz. is probably much higher Exactly, they are all measured midband, as with most drivers. But JBL provides the distortion graphs for their woofers, and for the 2226 is rises to 10% at 30Hz which is very good compared to commerical woofers, and also very good as a woofer tuned a half octave below. But I would rather use a woofer tuned differently for 20Hz operation, however the 2226H was the only JBL woofer available to Mike at the time, and also he was after high efficiency due to limited amp power (<100W), and he did not require 20Hz operation. But I've used various JBL and 18-Sound low distortion professional woofers before and also use these in my own system, and I can honestly say they do sound a lot cleaner than commercial woofers. I personally believe 3% THD to be very, very good, which is what Adire Tumult achieves. > reducing harmonic distortion bhear v Looks like something got cut out there, could you repost it for me? Adrian |
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[33145]
33145
From: Richard Greene, [frasier.ford.com]
Subject: Re: JBL 2226 is not intended to be a subwoofer driver
URL: 18
|
I've heard many DIY infinite baffle subwoofers that used multiple 2235's or 2245's. Excellent drivers if one can afford them and have room for large ported enclosures or an opportunity to use the basement as the enclosure. North Creek's Leviathan 18" (similar to old Aura 1808) is better if you wanted to spend about $849 on a driver! -- its 19mm XMAX is double the linear stroke of the JBL 2245 but the driver is not double the price! The few words on the bottom of my prior post should have been deleted. |
Responses:
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33123
From: mikeported, [netcache2-acld.auckland.clix.net.nz]
Subject: Re: °°°Types of Distortions °°°
|
Push-pull configuration will reduce second order hamonics, but it would not cancel them completely. ofcourse,if they canceled completely then the forces would be linear and equal and perfectly opposite. i was just checking to be sure that it was 2nd order harmonics. I've found that on all drivers, distortion rises as they near their mechanical resonance region. This is primarily a result from the magnetic structure, and not the suspension or the diaphram interesting. speakers seem to 'bungy' really far by 'bungy'i meant go VERY far in excursion your words "driving the amp too hard", you might be referring to clipping i might be yes. |
Responses:
[33124]
33124
From: mikeported, [netcache2-acld.auckland.clix.net.nz]
Subject: oops hit post message to soon.
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its 'higher quality' isnt enough detail for me. You've limited distortion by merit of motor quality using Professional Series JBL parts, and this driver works better with lower distortion and tighter cone control in EBS enclosures than most commercial drivers do. See "JBL's Tech Note 8" for more information i read that,its good they used FEA to make it better . not many people actualy know anything about this,notice only you reply ,no one else how do you think the shiva motor compares to jbl 2226h? simply less effort went into it/? |
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33108
From: Adrian Mack, [dialup-196-157.wasp.net.au]
Subject: Magnetic Circuits
URL: My website, Peerless XLS 12 Dual PR Sub Project, 18LW1400 vented sub, Horns, etc.....
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Hello Again! If you are looking to model magnetic circuits, then check out the magnetic FEA offerings by "Vector Fields" and "Ansoft". There are free downloadable student versions of various FEA models on the Ansoft site. Its pretty good stuff too, so I reccomend you take a look at it if your interested in magnetic circuits. Adrian |
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33122
From: mikeported, [netcache2-acld.auckland.clix.net.nz]
Subject: Re: Magnetic Circuits
| Cool! |
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