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Old 4th January 2017, 05:23 AM   #1981
gkh is offline gkh  Austria
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Quote:
Originally Posted by Matthew Morgan J View Post
By the way , who was asking about refining some square piezo horns a while back? Was it GM or someone else? This conversation has grown so long now ..... I suppose i could scroll through the pages to find the exchange .... I have something that works VERY well as a piezo horn body with square dimensions ..... I was pleasantly surprised to find out that these measure better than the Goldwood 1016 horn body!
Hi MMJ,
glad you survived the holiday madness

IIRC it was @freddi who started the piezo discussion. I'm really looking forward to your new findings.

Regards
Gerald
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Old 5th January 2017, 06:29 AM   #1982
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Hi MMJ,
glad you survived the holiday madness
We are survivors! .... Hehe

I hope all of the DIYaudio folks had a great holiday season!!

Gerald, this time of year must be gorgeous in Austria ......

I have a question for you: Do you ever order from Thomann.de?

Thomann is carrying a driver that i thought i should mention, The 15LB100-8W, it was first brought to my attention by my friend Sebastian in Denmark, he owns a set of them ......

The 15LB100 has a respectable amount of motor strength for a budget PA 15 , enough motor force in fact to make it perfect for a KARLFLEX 15! (and also great for a few other 6th order designs i have been working on)...... The driver may not have seemed entirely attractive to some if they saw the same spec sheet that i was initially shown which stated a humble linear excursion rating of "5.5mm", but i noticed that the 5.5mm figure is based upon a very conservative formula ..... After looking at the gap depth and voicecoil length (which they also make available) and applying those measurements to the same formula that B&C, 18sound, JBL, and RCF uses to calculate their "Xmax" i end up with a much higher value for the 15LB100...... (Hvc-Hg)/2 + Hg/4 = 8mm+ of one-way XMAX!!

That formula above doesn't necessarily tell us where the 10% THD mark is, at least not precisely, it is only a rough approximation but still indicates that this driver is very conservatively rated making it an extraordinary performance value for that price!


https://www.thomann.de/intl/the_box_...speaker_15.htm

I have more driver options to share but i figured this would be a good place to start ...

Last edited by Matthew Morgan J; 5th January 2017 at 06:48 AM.
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Old 5th January 2017, 07:58 AM   #1983
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Quote:
Originally Posted by Matthew Morgan J View Post
We are survivors! .... Hehe

I hope all of the DIYaudio folks had a great holiday season!!

Gerald, this time of year must be gorgeous in Austria ......

I have a question for you: Do you ever order from Thomann.de?

Thomann is carrying a driver that i thought i should mention, The 15LB100-8W, it was first brought to my attention by my friend Sebastian in Denmark, he owns a set of them ......

The 15LB100 has a respectable amount of motor strength for a budget PA 15 , enough motor force in fact to make it perfect for a KARLFLEX 15! (and also great for a few other 6th order designs i have been working on)...... The driver may not have seemed entirely attractive to some if they saw the same spec sheet that i was initially shown which stated a humble linear excursion rating of "5.5mm", but i noticed that the 5.5mm figure is based upon a very conservative formula ..... After looking at the gap depth and voicecoil length (which they also make available) and applying those measurements to the same formula that B&C, 18sound, JBL, and RCF uses to calculate their "Xmax" i end up with a much higher value for the 15LB100...... (Hvc-Hg)/2 + Hg/4 = 8mm+ of one-way XMAX!!

That formula above doesn't necessarily tell us where the 10% THD mark is, at least not precisely, it is only a rough approximation but still indicates that this driver is very conservatively rated making it an extraordinary performance value for that price!


https://www.thomann.de/intl/the_box_...speaker_15.htm

I have more driver options to share but i figured this would be a good place to start ...
Hi MMJ,

weather is sunny but rather cold. Fortunately no snow here in the city

Sure I know Thomann, have also seen this particular driver before, but didn't think of it... Thanks for the hint. Now I just have to redraw the plans for the enclosure.

Best wishes
Gerald
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Old 6th January 2017, 10:20 AM   #1984
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Smile 15LB100 Karlflex chat

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Originally Posted by gkh View Post
Hi MMJ,

weather is sunny but rather cold. Fortunately no snow here in the city

Sure I know Thomann, have also seen this particular driver before, but didn't think of it... Thanks for the hint. Now I just have to redraw the plans for the enclosure.

Best wishes
Gerald
We ended up with a lot of rain, the change in weather is nice though as it is normally dry in Arizona Seems like it has been warmer than a typical winter here in the low desert so i just cleaned up my outdoor shop area, i think i might attempt to get a cabinet building project underway ...

Gerald, I hope your shop is indoors, i am sure it gets much colder at your latitude than it does here ....

That 15LB100 driver appears to be a good one for the price, my friend who owns the set doesn't have a DATS, WT3 (or similar device) so we were unable to verify T/S parameters but the driver performs as expected and matches simulations closely enough so that is a very good sign ....... If you like i can put you into contact with Sebastian and he can share his impression of those drivers with you ..... He has had the chance to compare them with various other drivers because he is always working on experimental DIY speaker projects over at his place ....... The Danish DIY audio community is incredibly active from what they tell me...



As with most drivers they will sound best once the suspension is broken-in (if you want to do it the fast way you can just drive the woofer with 30hz to 40hz sine waves overnight in free-air) ..



Gerald, what frequency do you plan on using these Karlflex 15s up to?

Being a 15" driver it should be good out to around 1khz before it's midrange dispersion starts getting too narrow as a general rule .... So 1khz is a good (maximum) crossover point limit unless you expect for your listening to always be straight out in front of the cabinet (on-axis) ......



NOTE: In theory there is a workaround to this "beaming" challenge using pattern controlling schemes.... One method is a slot shape aperture (obscuring the sides of the driver somewhat, or at least the upper portion of the sides) which acts like an acoustic lens of a sort (as i have heard it described by Mr XRK971) causing the upper-midrange energy to become more evenly dispersed in the horizontal plane ............... I tried the slot idea with the Karlflex and indeed it really does work , verified by polar measurements, but (for me)this effect was at the expense of knocking down the on-axis upper midrange output by some decibels and the PA310 really didn't have enough extra decibels to spare up in that range in my opinion so I decided to go without the K-slot on mine for the time being .....

The 15LB100 does have somewhat of a rising upper mid response according to it's published curves so it may do well with this sort of pattern control extending it's usefulness out to what looks like about 1.75khz ......... If someone really wanted to experiment with this it would be easy enough to do by first building the Karlflex cabinet according to the plans and then making easy modifications to the front panel (and taking measurements , refining, etc) ........

I personally plan to revisit the slot idea, because i now have some new tricks up my sleeve that i would like to try.

Last edited by Matthew Morgan J; 6th January 2017 at 10:27 AM.
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Old 6th January 2017, 02:09 PM   #1985
gkh is offline gkh  Austria
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Originally Posted by Matthew Morgan J View Post
Gerald, I hope your shop is indoors, i am sure it gets much colder at your latitude than it does here ....
My shop is definitely indoors, being either kitchen or linig room - and we have a temperature drop down to -20C forecasted...

Quote:
Originally Posted by Matthew Morgan J View Post
Gerald, what frequency do you plan on using these Karlflex 15s up to?

Being a 15" driver it should be good out to around 1khz before it's midrange dispersion starts getting too narrow as a general rule .... So 1khz is a good (maximum) crossover point limit unless you expect for your listening to always be straight out in front of the cabinet (on-axis) ......



NOTE: In theory there is a workaround to this "beaming" challenge using pattern controlling schemes.... One method is a slot shape aperture (obscuring the sides of the driver somewhat, or at least the upper portion of the sides) which acts like an acoustic lens of a sort (as i have heard it described by Mr XRK971) causing the upper-midrange energy to become more evenly dispersed in the horizontal plane ............... I tried the slot idea with the Karlflex and indeed it really does work , verified by polar measurements, but (for me)this effect was at the expense of knocking down the on-axis upper midrange output by some decibels and the PA310 really didn't have enough extra decibels to spare up in that range in my opinion so I decided to go without the K-slot on mine for the time being .....

The 15LB100 does have somewhat of a rising upper mid response according to it's published curves so it may do well with this sort of pattern control extending it's usefulness out to what looks like about 1.75khz ......... If someone really wanted to experiment with this it would be easy enough to do by first building the Karlflex cabinet according to the plans and then making easy modifications to the front panel (and taking measurements , refining, etc) ........

I personally plan to revisit the slot idea, because i now have some new tricks up my sleeve that i would like to try.
I have planned on using the K15 up to approx 250Hz, for the upper range I'll build some Mini-Karlsonators, 0,53 scale, with 2x TC9FD.

I'm really curious what you're gonna come up next!

Best wishes
Gerald
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Old 8th January 2017, 07:15 AM   #1986
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Thumbs up Modern K-variants on top of modern K-Variants!

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Originally Posted by gkh View Post
My shop is definitely indoors, being either kitchen or linig room - and we have a temperature drop down to -20C forecasted...
-20 c ! BRUTAL! Glad you have a way to do this indoors ..


Quote:
Originally Posted by gkh View Post

I have planned on using the K15 up to approx 250Hz, for the upper range I'll build some Mini-Karlsonators, 0,53 scale, with 2x TC9FD.
Gerald,
I love the sound of your plan! Be sure to get plenty of pictures to show us during the build and after you are finished building .....Would be very cool to see a system made entirely out of modern Karlson inspired speaker designs stacked! The Karlflex and Karlsonator are both modern K-Variants and at the same time are also both series tuned 6th order designs .....

The designs should play well together crossing over at 250hz but don't be afraid to move the crossover point up and down during listening tests to see what filter point sounds best to your ears (200hz , 250hz, 300hz etc) ...

If you are bi-amping then it should be very easy to get a pleasing tonal balance and will surely sound great!
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Old 9th January 2017, 04:45 AM   #1987
gkh is offline gkh  Austria
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Originally Posted by Matthew Morgan J View Post
-20 c ! BRUTAL! Glad you have a way to do this indoors ..




Gerald,
I love the sound of your plan! Be sure to get plenty of pictures to show us during the build and after you are finished building .....Would be very cool to see a system made entirely out of modern Karlson inspired speaker designs stacked! The Karlflex and Karlsonator are both modern K-Variants and at the same time are also both series tuned 6th order designs .....

The designs should play well together crossing over at 250hz but don't be afraid to move the crossover point up and down during listening tests to see what filter point sounds best to your ears (200hz , 250hz, 300hz etc) ...

If you are bi-amping then it should be very easy to get a pleasing tonal balance and will surely sound great!
As soon as the sawdust has settled, I'll start making fotos :-D Glad you approve of my idea!

One more question:
If I have to mount the K'nator 0.53x flush under the ceiling (not at home, another project), do I have to turn it upside down?
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Old 10th January 2017, 12:58 PM   #1988
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Talking There is no shame in the ole Trial & Error

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If I have to mount the K'nator 0.53x flush under the ceiling (not at home, another project), do I have to turn it upside down?
I would test both ways to see which yields better results, but yes upside down would probably be the first thing i would try...

After putting it up there you could play some music over the K'nator and walk around the room while listening to confirm that there is sufficient coverage .......

You can always tilt the cabinet down by several degrees+ if that is what it takes to optimize...
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Old 14th January 2017, 07:14 AM   #1989
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Talking Thomann will also ship to the other side of the planet

NOTE:
If any folks in the United States are curious about that 15LB100-8W driver from Thomann you guys should know that Thomann has a very reasonable shipping rate to the United States, as long as the order is under a certain weight limit (at least that was the deal when i checked a few weeks ago) ...
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Old 14th January 2017, 07:30 AM   #1990
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Thumbs up Brands unwilling to hype up their calculation

As i mentioned earlier: one of the things that makes the 15LB100 a good value is the fact that it's Xmax figure was calculated using a conservative formula, and when you apply the less conservative formula that many popular brands use currently (like B&C , 18sound , RCF and others) you find that the Xmax figure you end up with for the 15LB100 is very competitive, especially at that price!

There are other brands that also rate conservatively and likewise also offer competitive products that people may have passed up because their figures aren't as hyped.... But you don't have to take my word for it, recalculate and see for yourself!

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Last edited by Matthew Morgan J; 14th January 2017 at 07:38 AM.
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