This is not a debate. This is about basic understanding of how a driver operates. Whether or not you choose to understand how it works does not change the laws of physics that operate here. This is my last post on this as you should be taking a physics class to get a basic understanding first.
Quite simply high inductance and more importantly variation in inductance has drastic effects on the distortion of the driver. Flux modulation has even more drastic effects. See the corner of the klippel distortion poster. Look at the lines for Le(x) and Le(i) and see which symptoms are checked off.
There is nothing to debate with this. In addition you have the change in the frequency response curve which will affect things at the crossover point whether you use a passive or active crossover. In a passive it is even more severe as the change in Le in turn changes the impedance at the crossover point.
Ok one more time with some worked through examples. While I have the time to debate the benefits of our drivers, I just do not have the time to go through basic physics but I will give you a few here anyway.
This is the equation we look at for force in a driver:
B*l*i = F and F = ma
That means B(flux density)*l(length of wire in gap)*i(current) = mass * acceleration.
Lets keep things very simple and say that B = 10 and l= 1 and mass = 100 grams
So 10*1*i = 100 * a
Lets put in 1 amp for i
10*1*1 = 100 * a
divide both sides and we get a = 0.10
Now lets put in more current and make i = 10amp
10*1*10 = 100 *a
divide both sides by 100 and 1 = 1.0 now. Increasing current increased acceleration.
now lets double the length of wire in the gap and double Bl which to you should make it accelerate much faster. B still equals 10. l now = 2. But now since there is 2x the length of wire, the resistance has doubled so current is cut in half.
10*2*5 = 100 * a
divide again and now a still equals 1.0. I hope this clears things up some for you.
Now lets double mass to 200
10*2*5 = 200 * a
divide by 200 and a now equals .50. By your statements this would prove your point. however what happens when we again double current
10*2*10 = 200 *a
Divide and now a again = 1.0. Current is the driving force that controls the acceleration. Without it, there is no acceleration.
Now imagine for a minute that inductance changes with excursion and as a result that current varies from about 10 amp on the outward stroke to 2amp on the inward stroke from +10mm to -10mm.
As the driver goes out current increases. As it goes in, current decreases. That may create a problem to the way the driver reacts. That may be something that should be taken care of in the design.
So you are saying that sine wave will not have the same time from rest to peak as it does from peak back to rest? You may also want to get a basic understanding of what a sine wave actually is. If these times are different, the actual frequency being played is changed. A 20hz sine wave has to oscillate 20 times per second. If it doesn't it is no longer a 20hz tone.
Yes there are distortions that actually alter this to some extent, but they will distort the shape of the curve, not the time that the cycle takes to be completed.
If your drivers are oscillating out of control, then they are not operating as they should. You can take a driver and play a full sine wave or even the first 1/2 of the pulse. You can also look at the position of the driver throughout this pulse and see where it is. If the permanent magnetic field is fixed and not moving, and if current is not changing throughout the stroke, it should track very close to where it should be.
Again though, 95% of drivers don't have flux fixed in the gap. It moves. 95% of drivers don't have constant inductance so the amount of current is continually changing. This leads to distortion of the signal.
Again see the equations solved above showing acceleration with relation to current. This is not a case of constant acceleration so you cannot compare it. If you throw the woofer off of 20 story building and if you throw the volvo off the top of the same building which accelerates faster? They are both the same because the force which is applied by gravity is the same in either case.
These of course are not my graphs. Adire was pretty much a direct competitor for a number of years. That doesn't change the fact that the findings of the paper shed some good insight into this. This also shows a quite small change in Le. Yes, 78% may seem large but I have seen drivers that will vary as much as 500% over their full travel.
Again, here is something more typical in the top curve here of a driver that has a typical S shaped Le curve. If you planned to take that driver to 500hz, 1KHz, etc, do you think the difference in response would have an issue with the implementation of the crossover?
The laws of physics do not know what size the driver is. They apply to all drivers.
If your only force came from the suspension then that would be the case. However your force comes primarily from the motor, or at least it should. You double mass and at the same time double the force that starts and stops it when you apply more current.
Again these were not my test. I have added mass to drivers before. Lots of it. You do hear a huge difference.... that being lower levels. Apply more current and you're back to the same point. However I can take 2 drivers, one with the full copper sleeve on the pole, and one without. The difference in sound is quite evident due to the distortion and inductance related issues.
Actually you could. The AV15X does have 2 resonances, a cone and dustcap resonance represented by the 2 bumps at 1Khz and 2.5Khz. They are caused by the aluminum so we'd need different materials to make a midrange out of them. They aren't intended to play this high though and we have TD woofers to do this. However other than those 2 spikes, they play very nice midrange. Some of the best vocal range I have every heard. They have a "big rubber surround"
John
Actually you could. The AV15X does have 2 resonances, a cone and dustcap resonance represented by the 2 bumps at 1Khz and 2.5Khz. They are caused by the aluminum so we'd need different materials to make a midrange out of them. They aren't intended to play this high though and we have TD woofers to do this. However other than those 2 spikes, they play very nice midrange. Some of the best vocal range I have every heard. They have a "big rubber surround"
John
I have been wanting to try my AV15X as a bass bin for my ribbon designs for a long time. I currently use the TD12S in a sealed box 60Hz to 400Hz but I could use the AV15X/2PRs to build full range 3 way and run it from 20Hz to 400Hz.
I have new RAAL ribbons coming (time for an upgrade over the Neopro5is). I also will be trying the 18sound 8ND460 out with those ribbons. Adding the AV15X with an active XO so I can have a gain structure to maximize the sensitivity would be cool.
I agree to disagree!
Hi John,
My whole argument in this thread driver ethos is to : “ Move the largest Sd with the lowest Mms and highest Bl that the required bandwidth allows. “
Most speaker designers agree this is the best way to reduce the vast majority of driver distortions.
Anyone reading my posts and attachments will clearly see where I am coming from, they are of course free to disagree, but I don’t do ambiguity!
So how can you possibly justify twisting my words to state that I am promoting greater driver travel...? You have either misrepresented my views or misunderstood them. See your post 97 –
“ Your statement above contradicts the other part. As you have stated, you want the driver to move fast or have high speed, meaning travelling farther over time. Again this means it has to travel farther over the same time period requires the driver moving to farther excursions. If you want to keep excursion down, then the speed is decreased.
I understand that your commercial interest forces you to respond with an avalanche of technical “ justification “ to defend AE’s USP, every manufacturer needs something to differenciate their product from the competition. But I am disapointed in your methods and statements.
Anyway, " Thats about all I have to say 'bout that!"
Cheers
Derek.
Hi John,
My whole argument in this thread driver ethos is to : “ Move the largest Sd with the lowest Mms and highest Bl that the required bandwidth allows. “
Most speaker designers agree this is the best way to reduce the vast majority of driver distortions.
Anyone reading my posts and attachments will clearly see where I am coming from, they are of course free to disagree, but I don’t do ambiguity!
So how can you possibly justify twisting my words to state that I am promoting greater driver travel...? You have either misrepresented my views or misunderstood them. See your post 97 –
“ Your statement above contradicts the other part. As you have stated, you want the driver to move fast or have high speed, meaning travelling farther over time. Again this means it has to travel farther over the same time period requires the driver moving to farther excursions. If you want to keep excursion down, then the speed is decreased.
I understand that your commercial interest forces you to respond with an avalanche of technical “ justification “ to defend AE’s USP, every manufacturer needs something to differenciate their product from the competition. But I am disapointed in your methods and statements.
Anyway, " Thats about all I have to say 'bout that!"
Cheers
Derek.
New PD 18 inch spec
Hi Tinitus,
PM received and understood!
I have just received the attached spec on the new PD 1850. Looks slightly worse than the old PD 1850 for my purpose but might suit some folks better.
A buddy of mine built a couple of coffee tables out of an old whiskey barrel. He basically ran the barrel through a band saw and fitted a circular MDF end plate to each half, fitted with a PD 1850 in it.
He then placed a glass table top ( circular ) on top of each barrel, ( the drivers were downwards facing ) and put 6 inch CNC 'd brass legs on the base to give the drivers an exit.
Cover the whole lot with a black velvet table cloth and Voila..! Twin killer subs, each approx 160 litres of air and you think they are part of the furniture.
The sound in his large home cinema room is very scary, a kilo watt of amp on each, a DEQX to Xover and room Eq and you are soon going down the rabbit hole when the big moments hit the screen.
He still dems the old T-Rex scene in the original Jurassic Park, he puts a glass of water on top of the table and it ripples even more than the one on screen... great fun!
Cheers
Derek.
Hi Tinitus,
PM received and understood!
I have just received the attached spec on the new PD 1850. Looks slightly worse than the old PD 1850 for my purpose but might suit some folks better.
A buddy of mine built a couple of coffee tables out of an old whiskey barrel. He basically ran the barrel through a band saw and fitted a circular MDF end plate to each half, fitted with a PD 1850 in it.
He then placed a glass table top ( circular ) on top of each barrel, ( the drivers were downwards facing ) and put 6 inch CNC 'd brass legs on the base to give the drivers an exit.
Cover the whole lot with a black velvet table cloth and Voila..! Twin killer subs, each approx 160 litres of air and you think they are part of the furniture.
The sound in his large home cinema room is very scary, a kilo watt of amp on each, a DEQX to Xover and room Eq and you are soon going down the rabbit hole when the big moments hit the screen.
He still dems the old T-Rex scene in the original Jurassic Park, he puts a glass of water on top of the table and it ripples even more than the one on screen... great fun!
Cheers
Derek.
PDF too big to post
Sorry PDF file too big to post.
If you PM me I can send it that way.
Cheers
Derek.
Sorry PDF file too big to post.
If you PM me I can send it that way.
Cheers
Derek.
Its ok, Blue Aran show the not yet released specs on their site
Oh, I see them on PD site now too
Thanks anyway, but its way too expencive
They sell perfectly good driver at around 160 english pounds
PDN.15BR40 looks perfect to me
And thats closer to my limit
But in this thread we better stick to AE drivers 😉
Though with the claims made, like "best bass I have ever heard", some comparison drivers is ok too
Please stay on topic
Driver comparisons
Hi Tinitus,
Yes the new 18 inch PD driver is very expensive, I think the 15 inch drivers are better value by far, diminishing returns and all that. Also the 15BR40 and 158 are really smooth out to 2KHz then gentle roll off, the 18 inch can’t do that.
Anyone got the AE 12 M or 15 M drivers in the UK that wants to do a comparison with the PD 12 MH and 15 inch 158 and 1550 drivers?
I have access to an anechoic chamber plus some cool measurement software.
Cheers
Derek.
Hi Tinitus,
Yes the new 18 inch PD driver is very expensive, I think the 15 inch drivers are better value by far, diminishing returns and all that. Also the 15BR40 and 158 are really smooth out to 2KHz then gentle roll off, the 18 inch can’t do that.
Anyone got the AE 12 M or 15 M drivers in the UK that wants to do a comparison with the PD 12 MH and 15 inch 158 and 1550 drivers?
I have access to an anechoic chamber plus some cool measurement software.
Cheers
Derek.
I just received two TD15Hs Wednesday. It took me until this afternoon to get them into my cabinets. My intention is to break them in with music.
Anyway, when they are broken in I will do some measurements and post the results.
I did a quick run with my Woofer Tester 2 and got an F3 of 24 Hz and the impedance curve was really impressive. They are replacing a pair of JBL 2235s.
When the suspension loosens up I'll do a complete test run and contrast/compare that with a run of one of my JBL 2235Hs.
Initial listening impressions seem to show an improved bottom end over the JBLs and the mid to upper mid bass seems cleaner to my ears. They are crossed at 400 Hz right now with a second order passive filter.
Even though the listening test is subjective, I think John did a very good job with these drivers. The mechanical construction is excellent as is the fit and finish.
This was a quick run (driver in open air) straight out of the box. I did not do a Vas test yet:
Anyway, when they are broken in I will do some measurements and post the results.
I did a quick run with my Woofer Tester 2 and got an F3 of 24 Hz and the impedance curve was really impressive. They are replacing a pair of JBL 2235s.
When the suspension loosens up I'll do a complete test run and contrast/compare that with a run of one of my JBL 2235Hs.
Initial listening impressions seem to show an improved bottom end over the JBLs and the mid to upper mid bass seems cleaner to my ears. They are crossed at 400 Hz right now with a second order passive filter.
Even though the listening test is subjective, I think John did a very good job with these drivers. The mechanical construction is excellent as is the fit and finish.
This was a quick run (driver in open air) straight out of the box. I did not do a Vas test yet:
An externally hosted image should be here but it was not working when we last tested it.
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