Hey Matthew, DIYaudio says that you have run out off space for incomming post
Yeah , i just had to delete some old emails to make some room ......
all better now
Panel Flex perhaps
Sebastian,
Sounds like you initially had the s1 stuffing density about right ... It may have been beneficial to make the s1 section a little bit wider (yours is 2 or 2.5 inches or 6.3 cm right?) , a little more airspace in there with stuffing would provide some additional damping for the midbass ... In my Karlflex 12 prototype i gave the S1 section 4" width (10cm) ..
The extra break-in time should help those drivers to some extent which is a good thing but i suspect that it is only a small part of the equation, meaning something like "Panel Flex" may be what is causing the undesirable ringing resonance and colouration you are hearing ... The reason i say this is because the symptoms you describe match those of Panel Flex perfectly so i think this is a strong possibility ... Since you said the problem still occurs without the front-panel/front-chamber then it helps us narrow down the offending panels a bit A bifurcate or trifurcate style bracing strategy would fix this problem and tighten up your sound , this would be very easy to add to the panel that forms the interchamber duct (above the driver) .... but maybe not so easy to add to the s1 panel after the fact (post build)..
I will reply to your email now, and share some ideas with you about this ...
By the way Sebastian, I have an unrelated question for you, do the Danish include KRAMPUS into holiday traditions? I know Krampus has been revived in some parts of Europe like Germany and Austria .... This looks like fun!
https://www.facebook.com/jehlaweb/videos/1320641707946746/
Sebastian,
Sounds like you initially had the s1 stuffing density about right ... It may have been beneficial to make the s1 section a little bit wider (yours is 2 or 2.5 inches or 6.3 cm right?) , a little more airspace in there with stuffing would provide some additional damping for the midbass ... In my Karlflex 12 prototype i gave the S1 section 4" width (10cm) ..
The extra break-in time should help those drivers to some extent which is a good thing but i suspect that it is only a small part of the equation, meaning something like "Panel Flex" may be what is causing the undesirable ringing resonance and colouration you are hearing ... The reason i say this is because the symptoms you describe match those of Panel Flex perfectly so i think this is a strong possibility ... Since you said the problem still occurs without the front-panel/front-chamber then it helps us narrow down the offending panels a bit
A bifurcate or trifurcate style bracing strategy would fix this problem and tighten up your sound , this would be very easy to add to the panel that forms the interchamber duct (above the driver) .... but maybe not so easy to add to the s1 panel after the fact (post build)..I will reply to your email now, and share some ideas with you about this ...
By the way Sebastian, I have an unrelated question for you, do the Danish include KRAMPUS into holiday traditions? I know Krampus has been revived in some parts of Europe like Germany and Austria .... This looks like fun!
https://www.facebook.com/jehlaweb/videos/1320641707946746/
Matthew:
My S1 is 8 cm wide.
There is bracing it is just covered with stuffing. I had two bracings going from the bass magnet to S1 panel + a bigger one going from bass panel to S1 panel. Then one from the exit duct (p2) to the upper stubs. But it could still be a problem, so I'll try to do some more.
No we don't have the Krampus Holiday here, think it is a German thing
My S1 is 8 cm wide.
There is bracing it is just covered with stuffing. I had two bracings going from the bass magnet to S1 panel + a bigger one going from bass panel to S1 panel. Then one from the exit duct (p2) to the upper stubs. But it could still be a problem, so I'll try to do some more.
No we don't have the Krampus Holiday here, think it is a German thing
Celebrating Kramp(m)us
I was wondering how widespread the Krampus thing had become .... Some young folks here had taken an interest in the legend and had organized some Krampus themed holiday events a few years ago ..... This year there is a Krampus movie coming out, i think it is supposed to hit the theater any day now so many more Americans will suddenly become aware of Krampus through the movie ...
Ok, Sebastian, about the box , S1 section is 8cm? I see ..... NOTE: I feel as though that S1 panel should effect tonal balance in these boxes with some effect upon tuning as well, although Akabak will certainly show the latter effect but may not tell the entire story regarding the midbass presence effect , of course i would have to test this to verify the theory ......... I made mine 10cm but if i would have made it wider i think the Karlflex12 would not have had enough midbass presence (unless i reduced the density of the stuffing) .... Your situation is very different though since you seem to have an overabundance of midbass presence with both of your 15s , not surprising since that can be the nature of pro 15s (known for excelling in the midbass range) ....
I am sitting here reviewing the photo that you posted recently with the newly added bracing circled in red and some lining circled in blue ......
Good moves on the added bracing, just keep in mind that longer bracing tends to be more effective than point bracing when it comes to deadening offensive panels (just not always as easy to implement after the fact i know) ........
By the way, there is a fun and easy test that you can do which can sometimes help track down the problematic panel (if it happens to be one of the outside panels) : Just play some pink noise or some music with plenty of midbass content , play it with some volume, and proceed to feel all external panels by hand as the music is playing, and you may find that one or a few panels vibrate excessively (often can be a problem at the high pressure end of the cabinet, for example you may find that it is the side-panels down near the driver which are causing the problem) ........... Any panels that vibrate significantly need to be braced to reduce losses and reduce colourations ...
Ideally (but not realistically) there wouldn't be any panel flex or vibration anywhere to be felt on the box's panels as if it were made of thick concrete!
but that is not practical 
, there is a point of diminishing returns when it comes to bracing so we cannot go totally overboard, it is good practice to just use standard bracing methods and then go back and specifically reinforce "hot spots" if there are any ...
Sebastian, i had some additional ideas for bracing that you may find helpful ,I made a sketch for you ...
Matthew:
No we don't have the Krampus Holiday here, think it is a German thing
I was wondering how widespread the Krampus thing had become .... Some young folks here had taken an interest in the legend and had organized some Krampus themed holiday events a few years ago ..... This year there is a Krampus movie coming out, i think it is supposed to hit the theater any day now so many more Americans will suddenly become aware of Krampus through the movie ...
Ok, Sebastian, about the box , S1 section is 8cm? I see ..... NOTE: I feel as though that S1 panel should effect tonal balance in these boxes with some effect upon tuning as well, although Akabak will certainly show the latter effect but may not tell the entire story regarding the midbass presence effect , of course i would have to test this to verify the theory ......... I made mine 10cm but if i would have made it wider i think the Karlflex12 would not have had enough midbass presence (unless i reduced the density of the stuffing) .... Your situation is very different though since you seem to have an overabundance of midbass presence with both of your 15s , not surprising since that can be the nature of pro 15s (known for excelling in the midbass range) ....
I am sitting here reviewing the photo that you posted recently with the newly added bracing circled in red and some lining circled in blue ......
Good moves on the added bracing, just keep in mind that longer bracing tends to be more effective than point bracing when it comes to deadening offensive panels (just not always as easy to implement after the fact i know
) ........ By the way, there is a fun and easy test that you can do which can sometimes help track down the problematic panel (if it happens to be one of the outside panels) : Just play some pink noise or some music with plenty of midbass content , play it with some volume, and proceed to feel all external panels by hand as the music is playing, and you may find that one or a few panels vibrate excessively (often can be a problem at the high pressure end of the cabinet, for example you may find that it is the side-panels down near the driver which are causing the problem) ........... Any panels that vibrate significantly need to be braced to reduce losses and reduce colourations ...
Ideally (but not realistically) there wouldn't be any panel flex or vibration anywhere to be felt on the box's panels as if it were made of thick concrete!
but that is not practical , there is a point of diminishing returns when it comes to bracing so we cannot go totally overboard, it is good practice to just use standard bracing methods and then go back and specifically reinforce "hot spots" if there are any ... Sebastian, i had some additional ideas for bracing that you may find helpful ,I made a sketch for you ...
An externally hosted image should be here but it was not working when we last tested it.
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That Krampus thing looks like something from Lord of the rings, or people plaing those role play/games (don't know the english term)
Yes I think i'll have to go all in the bracing department, to see if that helps and then do the "handtest"
Making the cabinet sturdy is always a challenge, unless weight and cost is no problem.
What is your thought of combining different kinds of wood/material to get better dampning. I had a conversation with a hifi buddy, who's opinion I respect in this hobby. He believed that if you had to different materials with 2 different resonances, putting them together would not damp those resonances, you would just create another.
Lets say that material 1 has a resonance of 100 hz and nr. 2 has 200hz then put together it would be 150hz. So you just shift resonance not damping them
I know that many companies in the speaker industry does that, but his argument also rings a bell. He believes it comes down to thickness, not the combination of materials. Food for thought
Nice drawing, thanks
Yes I think i'll have to go all in the bracing department, to see if that helps and then do the "handtest"
Making the cabinet sturdy is always a challenge, unless weight and cost is no problem.
What is your thought of combining different kinds of wood/material to get better dampning. I had a conversation with a hifi buddy, who's opinion I respect in this hobby. He believed that if you had to different materials with 2 different resonances, putting them together would not damp those resonances, you would just create another.
Lets say that material 1 has a resonance of 100 hz and nr. 2 has 200hz then put together it would be 150hz. So you just shift resonance not damping them
I know that many companies in the speaker industry does that, but his argument also rings a bell. He believes it comes down to thickness, not the combination of materials. Food for thought
Nice drawing, thanks
Resonance chat
Yessir, i think the Roleplay/Cosplay aspect is a big part of it, like the twisted counterpart to this other popular holiday cosplay guy
hehehe
Right, and it is one of those things that Akabak cannot help us with, so we are just left to figure it out for ourselves...... The challenge of it can be fun (within reason) and when you finally do figure it out you get to enjoy a great satisfying feeling of accomplishment!
This is a great question I think your friend is generally correct as in slapping together two different panels made of different types of wood .... There are some types of material that do absorb energy in a way that is very different than wood so that scenario would not be the same ...
It is my understanding that when it comes to panel resonance you in essence will have all of the same factors that determine a driver's FS (free-air resonance) such as "compliance" which is the same as a driver's VAS figure (suspension stiffness), and "moving mass" weight just like a driver's MMS figure, and then also the "effective radiator area" which is equivalent to a driver's SD figure ......... It is the interplay between those above factors which will result in your resonant frequency ...... You can sort of think of it like a weight attached to the end of a spring ...
Then there is the behavior of that resonance: Q or Damping as in QES/QMS (electrical/mechanical damping) but since there is no motor attached to your panel i am guessing that only QMS would apply here ...
^This^ applies to a drum's resonant tuning too
NOTE: any chamber of air behind the diaphragm/cone/drum skin/Panel can have an effect upon resonance as well because it can act like an air suspension spring and changes the VAS (compliance) figure (but then it is not technically "free-air" anymore).
So , ok back to how this applies to wooden panels: when you add a long brace in a bifurcate fashion you drastically reduce the VAS, MMS and SD figures by basically splitting one big panel radiator into two smaller panel radiators which in turn will drive the panel's resonances up high enough to hopefully avoid any more problems
................ If the box is very wide a person could go with trifurcate style bracing to break up those larger panels ...
That Krampus thing looks like something from Lord of the rings, or people plaing those role play/games (don't know the english term)
Yessir, i think the Roleplay/Cosplay aspect is a big part of it, like the twisted counterpart to this other popular holiday cosplay guy
hehehe Yes I think i'll have to go all in the bracing department, to see if that helps and then do the "handtest"
Making the cabinet sturdy is always a challenge, unless weight and cost is no problem.
Right, and it is one of those things that Akabak cannot help us with, so we are just left to figure it out for ourselves...... The challenge of it can be fun (within reason) and when you finally do figure it out you get to enjoy a great satisfying feeling of accomplishment!
What is your thought of combining different kinds of wood/material to get better dampning. I had a conversation with a hifi buddy, who's opinion I respect in this hobby. He believed that if you had to different materials with 2 different resonances, putting them together would not damp those resonances, you would just create another.
Lets say that material 1 has a resonance of 100 hz and nr. 2 has 200hz then put together it would be 150hz. So you just shift resonance not damping them
This is a great question
I think your friend is generally correct as in slapping together two different panels made of different types of wood .... There are some types of material that do absorb energy in a way that is very different than wood so that scenario would not be the same ...It is my understanding that when it comes to panel resonance you in essence will have all of the same factors that determine a driver's FS (free-air resonance) such as "compliance" which is the same as a driver's VAS figure (suspension stiffness), and "moving mass" weight just like a driver's MMS figure, and then also the "effective radiator area" which is equivalent to a driver's SD figure ......... It is the interplay between those above factors which will result in your resonant frequency ...... You can sort of think of it like a weight attached to the end of a spring ...
Then there is the behavior of that resonance: Q or Damping as in QES/QMS (electrical/mechanical damping) but since there is no motor attached to your panel i am guessing that only QMS would apply here ...
^This^ applies to a drum's resonant tuning too
NOTE: any chamber of air behind the diaphragm/cone/drum skin/Panel can have an effect upon resonance as well because it can act like an air suspension spring and changes the VAS (compliance) figure (but then it is not technically "free-air" anymore).
So , ok back to how this applies to wooden panels: when you add a long brace in a bifurcate fashion you drastically reduce the VAS, MMS and SD figures by basically splitting one big panel radiator into two smaller panel radiators which in turn will drive the panel's resonances up high enough to hopefully avoid any more problems
................ If the box is very wide a person could go with trifurcate style bracing to break up those larger panels ...
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from the little C-path midbass horn I had built, I can tell with proper bracing, 5/8" Baltic birch should make a sufficiently rigid cabinet. 3/4" BB was used for the baffle and access panel http://i.imgur.com/7E9h3Bz.jpg
Matthew.
It is a good analogy with the panels vs speakercone, makes sence.
I did some more bracing and it surely helped. The sound is not so colored anymore, but I still get that weird wack/honk around 200 hz, especially from snares?!
I also did the handtest and I don't think I was getting "out of the ordinary", vibrations. The side panels is 1,5 cm plywood and there is internal deviders, due to design (s1, basspanel and interchamber duct).
Maybe S1 needs resizing?!
It is a good analogy with the panels vs speakercone, makes sence.
I did some more bracing and it surely helped. The sound is not so colored anymore, but I still get that weird wack/honk around 200 hz, especially from snares?!
I also did the handtest and I don't think I was getting "out of the ordinary", vibrations. The side panels is 1,5 cm plywood and there is internal deviders, due to design (s1, basspanel and interchamber duct).
Maybe S1 needs resizing?!
Yule-Horn
Freddi ,
Surely that box will be sturdy ... It is made of the right stuff, and with that dual bracing scheme (trifurcate) in the inside as well as mouth that horn should be rock solid ..
It is a little over 20" wide right? Access panel is on top?
Santa Claus needs to load this horn into his sleigh and get it over to your house!
Freddi ,
Surely that box will be sturdy ... It is made of the right stuff, and with that dual bracing scheme (trifurcate) in the inside as well as mouth that horn should be rock solid
.. It is a little over 20" wide right? Access panel is on top?
Santa Claus needs to load this horn into his sleigh and get it over to your house!
Thank you
HOORAY FOR PROGRESS!!
I am really glad to hear that it helped some ... Now that you have part of the problem worked out it would be a good time to pull the front panel off again to see if the strange clunk/honk colouration on snares will clear up, and if it does then we know that there needs to be a change made to the front chamber or stub-stack section ...
Possibly ... Just based upon the results that you reported from your recent S1 stuffing experiments it seems to me that you would be happier with the sound of a larger S1 size(CSA) using your original stuffing density ..... (maybe something to consider trying after you are done experimenting with the cab's front-chamber and if you still want further improvement at that point) .....
Matthew:
I tried different apertures and somehow the K- aperture was not so colored in the 200 hz region. The round aperture made this region more prominent (before it was the other way around, will have to do some more listening to be shure) Even with the aperture of I still had the problem and the weird sound seems to come from the cone and not above it. Could try with different stuffing (more) in the upper stubs.
The stuffing in s1 was back to normal density. Maybe I could try to move the s1 panel and make it 10 cm, it is 8 cm now, but that would also affect the entrance to the interchamber duct?! Maybe I could just widen the entrance of s1, so it would be like a waveguide??
I tried different apertures and somehow the K- aperture was not so colored in the 200 hz region. The round aperture made this region more prominent (before it was the other way around, will have to do some more listening to be shure) Even with the aperture of I still had the problem and the weird sound seems to come from the cone and not above it. Could try with different stuffing (more) in the upper stubs.
The stuffing in s1 was back to normal density. Maybe I could try to move the s1 panel and make it 10 cm, it is 8 cm now, but that would also affect the entrance to the interchamber duct?! Maybe I could just widen the entrance of s1, so it would be like a waveguide??
Exploring options
Sebastian,
Was this with the taller or shorter K-slot?
Looking forward to hearing what you will come up with through more listening tests ....
I was wondering if a K-slot would be a better choice with such a large front chamber (yours even exceeds the relative size of the front chamber in a classic Karlson)..
Yessir , S1 absolutely can be set up as a waveguide ... You could leave the top of S1 at 8cm then pull the bottom out to 12cm or even 15cm , giving you an expansion... You could even make the top of S1 a bit narrower if you wanted to try for more taper/expansion ..... Some of TB46's drawings were set up this way ..... The Karlsonator has an S1 that is shaped this way as well .....
I modeled this sort of thing in Akabak a number of times and it works well , although it doesn't tune as low for a given cab height (assuming interchamber duct length is the same, the difference was just a few hertz), but actually makes perfect sense for use in your taller complex Karlflex cabinet project
Sebastian,
Was this with the taller or shorter K-slot?
Looking forward to hearing what you will come up with through more listening tests ....
I was wondering if a K-slot would be a better choice with such a large front chamber (yours even exceeds the relative size of the front chamber in a classic Karlson)..
Yessir , S1 absolutely can be set up as a waveguide ... You could leave the top of S1 at 8cm then pull the bottom out to 12cm or even 15cm , giving you an expansion... You could even make the top of S1 a bit narrower if you wanted to try for more taper/expansion ..... Some of TB46's drawings were set up this way ..... The Karlsonator has an S1 that is shaped this way as well .....
I modeled this sort of thing in Akabak a number of times and it works well , although it doesn't tune as low for a given cab height (assuming interchamber duct length is the same, the difference was just a few hertz), but actually makes perfect sense for use in your taller complex Karlflex cabinet project
its 20" wide inside - here's a graph - its not far from a corner and virtual corner from a bunch of stuff
http://i.imgur.com/tHPM6Kx.gif
http://i.imgur.com/tHPM6Kx.gif
Freddi ,
Looks good to me from about 60 on up to almost 300hz, what driver is loaded?
Was this a measurement by some other builder? or the designer?
that was a Community 12" "buyout" driver in the horn - I measured it in my extremely cluttered living room - with a 511 and phenolic mid-driver plus titanium Audax bullet tweeter, it sounds somewhat horrid. What's odd is that I think I would take the very poor measuring 1.875" diameter K-tube's sound on top of the 115BK below as "more natural" - the little K-coupler is just midbass but with a K-tube on top sounds more real on bowed bass and voice. I think overall I would pick a good little K over all my horns - although I'm fond of Klipsch's Heresy. To put my little KK-audio Karlson into action, I need a very strong cement for their loose and thick carpet - - any ideas?
Acoustic Control 115BK
Acoustic Control 115BK
Hi freddi,
Is the 115BK the same basic box as the X15, or is it smaller? I'm making slow progress on the box from 1188/1668, had a not very fun medical week and too much work @ work, and a new assistant...(I better stop complaining, it could be worse).
Regards,
P.S.: What are your dimensions for a "...good little K..."?
Is the 115BK the same basic box as the X15, or is it smaller? I'm making slow progress on the box from 1188/1668, had a not very fun medical week and too much work @ work, and a new assistant...(I better stop complaining, it could be worse).
Regards,
P.S.: What are your dimensions for a "...good little K..."?
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hi tb46 115BK made of 3/4" good birch plywood if it didn't have the front wing inset would be 27" tall by 20.5" wide by 13.7" deep with only about 2 cubic foot rear airspace for the back and middle chambers combined and one cubic foot for the front chamber. Response wise, it would not go "deep" but would fit into a midbass/fullrange device and would be much like a K12 on the low end but somewhat less cone excursion for a given peak transient. A 12 could be pretty good for this purpose.
size wise - I think the Transylvania Power Company cabinet and clones were derived from Karlson's 1965 "X15" two way system
Karlson seemed to make several differnt vents for his X15 - normally it had one small central vent flanked by an array of de-Q-ing holes (those can make a K sound more "agile" less resonant) but apparently there was a version for organ with an exponential horn up front and a large vent - this version is the one I think which set the 115BK and Transylvania KHYBOE size. Imageshack has deleted my picture so will have to see if it still exists on an old PC
btw, there was no damping material at all in my 115BK other than perhaps 1/4" felt at the very bottom
which is the access panel
rough drawing of 115BK - its about 4.3 cubic foot external bulk
tuning of 115BK with EVM15L
distortion at 20vrms outdoors for three LF points
115BK ~ ground plane response outdoors on a hill side
115BK front - radial aperture I think - the outer edge bevel makes it looks less so
BC2 combo amp version of 115BK
https://www.youtube.com/watch?v=ghaS2h7ja5c
A K12 in contrast at 16.75" wide external is about a cubic foot smaller in bulk than 115BK - here's rough dimensions derived
from a Karlson kit paper - this kit from what I can gather was sold with a blank port panel and had instructions for porting
various speakers of its day
size wise - I think the Transylvania Power Company cabinet and clones were derived from Karlson's 1965 "X15" two way system
Karlson seemed to make several differnt vents for his X15 - normally it had one small central vent flanked by an array of de-Q-ing holes (those can make a K sound more "agile" less resonant) but apparently there was a version for organ with an exponential horn up front and a large vent - this version is the one I think which set the 115BK and Transylvania KHYBOE size. Imageshack has deleted my picture so will have to see if it still exists on an old PC
btw, there was no damping material at all in my 115BK other than perhaps 1/4" felt at the very bottom
which is the access panel
rough drawing of 115BK - its about 4.3 cubic foot external bulk
tuning of 115BK with EVM15L
distortion at 20vrms outdoors for three LF points
115BK ~ ground plane response outdoors on a hill side
115BK front - radial aperture I think - the outer edge bevel makes it looks less so
BC2 combo amp version of 115BK
https://www.youtube.com/watch?v=ghaS2h7ja5c
A K12 in contrast at 16.75" wide external is about a cubic foot smaller in bulk than 115BK - here's rough dimensions derived
from a Karlson kit paper - this kit from what I can gather was sold with a blank port panel and had instructions for porting
various speakers of its day
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