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Would the AE TD15M be a good high end replacement for the K-33?


prerich

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The AE TD15M is currently used in the Avalon Acoustics Tessaract, I'm wondering if it could replace the K-33 in the Cornwall, La Scala, or Klipschorn? Here's the specs:

 

TD15M-8ohm
Fs: 34.7Hz
Qms: 5.09
Vas: 312 L
Cms: .3 mm/N
Mms: 70 g
Rms: 3 kg/S
Xmax: 6 mm(peak)
Xmech: 10 mm(peak)
Sd: 855 sqcm
Vd: 1.02L (p-p)
Qes: .35
Re: 6.6 ohm
Le: .2 mH
Z: 8 ohm
Bl: 17 T/m
Pe: 300W (cont.)
Qts: .33
1WSPL: 97.8 dB
2.83V: 98.56 dB
 
Would this be a fit or what?
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The TD15M is a monster woofer, it's considered one of the great ones from what I've read.  However, I've never heard of it being used in a CW, LS or Khorn.  There must be a reason for that.

 

Certainly the smart guys on those models will weigh in and give you solid advice.

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Well, the specs do vary from the K-33, so that is the first problem. The cabinet geometry and the throat sizes and reactance annulling are all dependent on these specs. 

 

A more fundamental question is why are you focused on the woofer. These systems do have their weaknesses, but the woofer would not be high on the list of things to "correct". 

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This is the one you want.

 


TD15M-4ohm
Fs: 34.7Hz
Qms: 5.09
Vas: 312 L
Cms: .3 mm/N
Mms: 70 g
Rms: 3 kg/S
Xmax: 6 mm(peak)
Xmech: 10 mm(peak)
Sd: 855 sqcm
Vd: 1.02L (p-p)
Qes: .35
Re: 3.2 ohm
Le: .2 mH
Z: 4 ohm
Bl: 11.81 T/m
Pe: 300W (cont.)
Qts: .33
1WSPL: 97.7 dB
2.83V: 101.7 dB
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Well, the specs do vary from the K-33, so that is the first problem. The cabinet geometry and the throat sizes and reactance annulling are all dependent on these specs. 

 

A more fundamental question is why are you focused on the woofer. These systems do have their weaknesses, but the woofer would not be high on the list of things to "correct". 

Naw, I've just got one sitting around doing nothing and wondered if I could put it in my Cornwall vertical that's all. If it's not a good match or fit, I'm going to sell it cheap.

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I ended up going with the K48 over the TD15M after conducting a week of side by side comparisons in a cabinet similar to a Cornwall. Hurd was there the entire time too - it actually surprised us a ton because we were going to purchase a ton of those drivers for our setups. These were older versions of the TD15M (like so far back it was a different company name) and I think the problem was related to a known issue with the suspensions - the suppliers could never get it right. I think all of that has been remedied now so I'd like to give it another try sometime using the modern stuff.

 

B&C makes some really good drivers too. I've only played with their 12" drivers, but I think they have 15" versions that'd work for horn loading.

 

I forget the model number, but Eminence makes a driver similar to the K48 too....is it Kappa Pro 15LF? Or something like that. Although for horn loading you'll probably want something else.

 

Speaking of which, I've always felt that the K33 was designed for the Khorn/Lascala and just happens to work well enough in a Cornwall....but really a Cornwall design is going to benefit from a driver optimized for a vented cabinet of that size. So really it's gonna be very application specific. Heck, even for Lascala versus Khorn - one might argue that it'd be worth the minor efficiency gains to go with a driver that doesn't dig as low.

Edited by DrWho
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I ended up going with the K48 over the TD15M after conducting a week of side by side comparisons in a cabinet similar to a Cornwall. Hurd was there the entire time too - it actually surprised us a ton because we were going to purchase a ton of those drivers for our setups. These were older versions of the TD15M (like so far back it was a different company name) and I think the problem was related to a known issue with the suspensions - the suppliers could never get it right. I think all of that has been remedied now so I'd like to give it another try sometime using the modern stuff.

 

B&C makes some really good drivers too. I've only played with their 12" drivers, but I think they have 15" versions that'd work for horn loading.

 

I forget the model number, but Eminence makes a driver similar to the K48 too....is it Kappa Pro 15LF? Or something like that. Although for horn loading you'll probably want something else.

 

Speaking of which, I've always felt that the K33 was designed for the Khorn/Lascala and just happens to work well enough in a Cornwall....but really a Cornwall design is going to benefit from a driver optimized for a vented cabinet of that size. So really it's gonna be very application specific. Heck, even for Lascala versus Khorn - one might argue that it'd be worth the minor efficiency gains to go with a driver that doesn't dig as low.

Yes, I'm familiar with that - I have one of the newer ones made by Acoustic Elegance. Bob's stuff is great!!!! I love his upgrades. I'm just curious to see how this would work.  I've heard of people using this driver in two way configurations too, it will run all the way up to 2khz. 

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I've got some of the td12h's on the way. Couldn't see spending that much on woofers that only had 6mm xmax so I bumped up to the h version. The 12 lets you cross over a little higher before it starts beaming as well. I've chatted with John quite as bit and you can tell he really has some old school pride of work. If nothing else I'm excited to have an American made product that was hand made with care by an expert craftsman. But, woofers that can be used as subs with 0.3 mh voice coil impedance (le)? Voice coil tolerances the width of a human hair? This stuff is likely way beyond what most people are used to. There's a 4-6 week waiting period on most everything and these things are used in several speakers that are well into the 5 digit price tag range, can't imagine they'll be anything but the cats meow.

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5mm will have excessive FMD when trying to cover three octaves (or more).

A normal woofer will, yes. Read their latest facebook post on this exact subject. They did a real world test at 100 db where actual material was being played rather than a simple test tone. A standard woofer had 15-20 db more distortion. Notice on the pictures, the gap on the bottom graph.  For whatever reason they have claimed elsewhere that their dipole woofers have virtually eliminated this issue.  This is exactly why I shelled out over a grand for three raw 12" drivers.  Otherwise, whats the point?  

https://www.facebook.com/aespeakers/posts/10153778505096866?comment_id=10153779314496866&notif_t=like

DOES THAT FULL COPPER FARADAY SLEEVE REALLY MAKE A DIFFERENCE? YES!

This is a question we are asked often. It is usually asked along with the question "why don't you have any distortion measurements then?" People often assume we have something to hide. You will see from the third party measurements here, that is definitely not the case. There are a few reasons we don't publish curves. The biggest to this point has been the time requirement to measure these curves. Most who want that data are able to measure it themselves and would be skeptical of our results anyway. Measuring THD curves is something we plan to work on over the next year though. Secondly if you look at a distortion sweep and take a quick snapshot of it at any frequency, you realize there is only one fundamental tone being played at a time. This isn't how music works. A kick drum creates excursion while a vocal is sung. A bass guitar note creates excursion while a guitar is played. These things happen simultaneously and the excursion created by the low tone affects the upper tones being played in a negative way. The current draw from the low frequencies creates flux modulation that affects the upper frequencies. Addressing the Le(x) distortion and Le(i) distortion in the motor is critical in solving this issue. A real world test should be able to measure distortion under excursion and with current applied. We are working on a test that will do just that to show what real world distortion looks like.

In the meantime, we are able to rely on some 3rd party tests to verify what we already know. Nearly all driver manufacturers claim their woofers to be the best, lowest distortion, etc. The reality is not everyone can be the best even if they claim to be. Our OEM customers choose our woofers because they do their own testing that verifies our woofers are the best. We have known this for over 15 years when our measurements and listening first proved that the Lambda Acoustics woofers were the lowest distortion and most accurate woofers available anywhere. When Lambda decided to close down over 10 years ago, we were not about to allow these woofers to disappear. We continued to make them here and improve upon them.

Now to look at some third party results. A few years back a DIY user took it upon himself to do a series of tests on different drivers. We of course provided several models that could be compared. Our woofers showed to be superior in terms of distortion and response for nearly every test. A few things really stand out. The first is in the distortion sweeps. Specifically the 3rd harmonic, H3 test. This third harmonic shows the effects flux modulation and also Le(x) non-linear distortion. When looked at on separate graphs shown on separate pages it is difficult to compare and see the significance of the measurements. When curves are isolated and compared directly it shows something much easier to distinguish. We took the original graphs and pulled the fundamental F1 and H3 distortion curves out for a comparison. Attached here are curves showing the TD12M vs three other drivers that are well known in the industry. The TD12M H3 distortion is significantly lower than the others throughout the midrange region by as much as 15-20dB over a significant range. This is a HUGE difference of distortion!

As a side note on these curves, look at the smoothness in the upper end of the TD12M response curve in comparison to all other drivers. This is something we work very hard to achieve.

Next we looked a multitone test that created a distortion spectrogram. Three tones were played with the center frequency at 500hz. Anything outside of these tones is distortion generated somewhere in the woofer. We took the TD12M and used its distortion plot to mask the plots of the other drivers. The red seen is how much MORE distortion those drivers have than the TD12M. They all have more. A LOT more. This is at 100dB output level. Here again we can see the H3 distortion clearly much higher than the TD12M in all of these drivers around and above 1500hz. Again, this is the issue with inductance related distortions. At the same time, we see significantly more distortion throughout the entire frequency range on the other drivers.

So does the FCFC work to lower distortion? ABSOLUTELY! We will have published measurements and data sheets to show our own results as time permits. In the meantime, these independent measurements speak significantly about the low distortion of our woofers. As you can tell we have nothing to hide other than the tricks we use to get these results!

 

10624574_10153778451121866_1481700713482

 

1929725_10153778451106866_90205241079415

Edited by MetropolisLakeOutfitters
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Dennis has a point....

 

That distortion info from AE is showing amplitude modulation distortion. Frequency modulation distortion doesn't create harmonics - it changes the actual pitch of the music based on how fast the diaphragm is moving. Amplitude distortions can create frequency modulation effects, but at some point the size of the diaphragm and the bandwidth it's covering will dominate.....and there's nothing more you can do at that point unless you add more drivers, or hornload the system. Even then, you will have a finite amount of frequency modulation distortion - so really the bigger question is how much is too much?

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Dennis has a point....

 

That distortion info from AE is showing amplitude modulation distortion. Frequency modulation distortion doesn't create harmonics - it changes the actual pitch of the music based on how fast the diaphragm is moving. Amplitude distortions can create frequency modulation effects, but at some point the size of the diaphragm and the bandwidth it's covering will dominate.....and there's nothing more you can do at that point unless you add more drivers, or hornload the system. Even then, you will have a finite amount of frequency modulation distortion - so really the bigger question is how much is too much?

I'm sufficiently all kinds of tripped out now.

To be honest the biggest reason I got the 14mm xmax version was so I could use them as subs in my jeep if I totally jack this project up. :) Hopefully the additional mass won't mess up the tone too much and it won't hurt anything in terms of noticeable sound quality vs. the M version with 6mm xmax.

Edited by MetropolisLakeOutfitters
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  • 2 years later...
On 12/26/2015 at 11:58 PM, DrWho said:

Speaking of which, I've always felt that the K33 was designed for the Khorn/Lascala and just happens to work well enough in a Cornwall....but really a Cornwall design is going to benefit from a driver optimized for a vented cabinet of that size. So really it's gonna be very application specific. Heck, even for Lascala versus Khorn - one might argue that it'd be worth the minor efficiency gains to go with a driver that doesn't dig as low.

Yep, like a K43, as I discovered. But for those who want some really great drivers. AE are tops. Expensive but worth it.

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