Drum recordings sound good!
Freddi,
I was able to find "The Beast" from DAFOS on youtube .... I first listened to it on my headphones , which are just mediocre studio style headphones but with a reasonably flat response .... The drum solo sounded just alright through the headphones but lacked dynamics and punch, it sounded somewhat 2-dimensional .......................
Then i went out to the living room where i currently have the Karlflex set up on the new Crown Drivecore amp, and i played "The Beast" on that system, which gave me a different impression.. Playing over the Karlflex this very same drum solo sounded more lively, and more dynamic! There was more subjective impact, and the drums really seemed to jump out at you (much more than the headphones anyway) ..... Turned up it sounds almost like having someone playing a drumset in the living room 🙂
I spent the next hour or more (lost track of time) listening to various drum solos on youtube ....😛
Freddi,
I was able to find "The Beast" from DAFOS on youtube .... I first listened to it on my headphones , which are just mediocre studio style headphones but with a reasonably flat response .... The drum solo sounded just alright through the headphones but lacked dynamics and punch, it sounded somewhat 2-dimensional .......................
Then i went out to the living room where i currently have the Karlflex set up on the new Crown Drivecore amp, and i played "The Beast" on that system, which gave me a different impression.. Playing over the Karlflex this very same drum solo sounded more lively, and more dynamic! There was more subjective impact, and the drums really seemed to jump out at you (much more than the headphones anyway) ..... Turned up it sounds almost like having someone playing a drumset in the living room 🙂
I spent the next hour or more (lost track of time) listening to various drum solos on youtube ....😛
Listen to Steve Clarke drum solos. He's really good. Yes, Karlsons have. Way of playing drum dynamics very well.
its probably "The Beast" track which gives DAFOS a max of 22dB dynamic range at the dynamic range database
Am i finding balance? =P
Ok guys,
I was really curious about what Freddi meant by "congested" when closing or narrowing the gap at the top of the K-slot .... Is the statement about "mids balancing" related to a midbass-to-midrange balance?
I decided i would just go all out and do something drastic to see if i could hear the change in midrange balance that Freddi is talking about, so i went ahead and just covered up the top 10 inches of the slot with cardboard to see what would happen, first i just held it by hand while playing music, then after that i taped it on and used a clamp to secure it solidly ..................
The difference? I like it
, and once again Freddi was correct ..... It did sound like it changed the midbass in relation to the midrange, and certain tracks that previously sounded too aggressive in the midrange now seem to balance out a little better with a bit more apparent midbass....... I suspect that this change gave me a little more subjective oomph and warmth between 80hz and 150hz or something along those lines but i will measure it to be sure of what is going on there ........ Sounds a little more "full" now, with well rounded bass on most recordings, even though i have confirmed that the fundamental is tuned too low now which is really not at all ideal, according to the DATS unit i am sitting at exactly 37hz for the FB, a 40hz tune should sound even better (because tuning any lower than 40hz is just counterproductive with the PA-310 driver in my opinion..
)......
I can see that the next Karlflex build will need to be tuned at least 3hz higher initially so that i can shape the K-slot in this same manner (looks kind of like an Inverted V shape right now) .......
I have a gameplan for this 🙂 , A Simple and easy-to-build 24" tall Karlflex with Freddi-mod cavity should do the trick, the Freddi-mod requires a few inches of internal vertical space which takes away enough length from the path to give me the 3hz or 4hz increase in tuning that is required to hit my 40hz target!
...
Everything is starting to come into focus now.
😀
............................................
I wasn't able to find the Steve Clarke drum solos that you guys are talking about but there are lots and lots of drum solo recordings out there to listen to on youtube (Including "The Beast" from DAFOS), here are a few other drum solos that i listened to:
https://www.youtube.com/watch?v=R1_DMYhr-aY
https://youtu.be/rorTZyGlLFA
https://youtu.be/F_T4YXhnveA
https://youtu.be/Wu3X6CQm56A
Ok guys,
I was really curious about what Freddi meant by "congested" when closing or narrowing the gap at the top of the K-slot .... Is the statement about "mids balancing" related to a midbass-to-midrange balance?
I decided i would just go all out and do something drastic to see if i could hear the change in midrange balance that Freddi is talking about, so i went ahead and just covered up the top 10 inches of the slot with cardboard to see what would happen, first i just held it by hand while playing music, then after that i taped it on and used a clamp to secure it solidly ..................
The difference? I like it
, and once again Freddi was correct ..... It did sound like it changed the midbass in relation to the midrange, and certain tracks that previously sounded too aggressive in the midrange now seem to balance out a little better with a bit more apparent midbass....... I suspect that this change gave me a little more subjective oomph and warmth between 80hz and 150hz or something along those lines but i will measure it to be sure of what is going on there ........ Sounds a little more "full" now, with well rounded bass on most recordings, even though i have confirmed that the fundamental is tuned too low now which is really not at all ideal, according to the DATS unit i am sitting at exactly 37hz for the FB, a 40hz tune should sound even better (because tuning any lower than 40hz is just counterproductive with the PA-310 driver in my opinion..)......I can see that the next Karlflex build will need to be tuned at least 3hz higher initially so that i can shape the K-slot in this same manner (looks kind of like an Inverted V shape right now) .......
I have a gameplan for this 🙂 , A Simple and easy-to-build 24" tall Karlflex with Freddi-mod cavity should do the trick, the Freddi-mod requires a few inches of internal vertical space which takes away enough length from the path to give me the 3hz or 4hz increase in tuning that is required to hit my 40hz target!
... Everything is starting to come into focus now.
😀............................................
I wasn't able to find the Steve Clarke drum solos that you guys are talking about but there are lots and lots of drum solo recordings out there to listen to on youtube (Including "The Beast" from DAFOS), here are a few other drum solos that i listened to:
https://www.youtube.com/watch?v=R1_DMYhr-aY
https://youtu.be/rorTZyGlLFA
https://youtu.be/F_T4YXhnveA
https://youtu.be/Wu3X6CQm56A
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Hi, following 🙂
I'm surprised that 3Hz would make such a negative difference ! I would have expected that 37Hz might be better than 40Hz.
Rather than clamping on cardboard, i would get some MDF etc. The cardboard is likely to flex.
I'm surprised that 3Hz would make such a negative difference ! I would have expected that 37Hz might be better than 40Hz.
Rather than clamping on cardboard, i would get some MDF etc. The cardboard is likely to flex.
MMJ - grab this at the lowest price at A-zon - much cheaper than the 3 copies in Germany currently on Ebay - its a reference recording and nothing but two extended drum solos Amazon.com: Buying Choices: Solo Drums
re:"congested" - here's one example I experienced - a 0.6" starting gap vs 1.2" in a small coupler loaded with an 18" - look at the graph - to the mic in one position, there was no significant difference - it sounded constipated with the 0.6" - the 1.2" gap was extremely nice sounding - imo some K-couplers need to be worked out by "ear" as a mic will not tell the story
perhaps there were many more slight changes in the aperture which would had similar effect (?)
but I guess the aperture on the left was just too constricted.
this is the same coupler to which I added a 20 liter cavity
here's a one-off higher aspect K18 which turned out nice sounding
re:"congested" - here's one example I experienced - a 0.6" starting gap vs 1.2" in a small coupler loaded with an 18" - look at the graph - to the mic in one position, there was no significant difference - it sounded constipated with the 0.6" - the 1.2" gap was extremely nice sounding - imo some K-couplers need to be worked out by "ear" as a mic will not tell the story
perhaps there were many more slight changes in the aperture which would had similar effect (?)
but I guess the aperture on the left was just too constricted.
this is the same coupler to which I added a 20 liter cavity
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An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
here's a one-off higher aspect K18 which turned out nice sounding
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
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24" for the simplified Karlflex will be great and about a half inch shorter than the original K12 which made its debut in the fall of 1954 and stayed the same size til Karlslon's death in Jan. 1973.
Balancing act
Zero D ,
Yes, exactly right, that cardboard did flex and moved a little too much, the duct tape i used provided a nice seal though, so i went ahead and placed some scrap ply over the front of the cardboard and then clamped it in place which seems to work 🙂
About the 3hz: this is just a prototype box, and i am just working out what fine adjustments to the design will need to be made in order to approach a 40hz extension with enough output to be useful as a small and highly portable PA system ... So why 40hz? .... The driver (A Dayton Pa-310) has a limited XMAX figure so it was never really meant to be a low-tuned subwoofer, although someone could use it that way in the right cabinet (if they really wanted to) it is just not ideal because the driver's modest excursion capabilities would severely limit the maximum output levels ... 40hz seems like a reasonable balance of extension and output and is fine for reproducing most modern music .....
Tuning lower also means that you lose some bottom-end efficiency unless you are willing to increase the size of the box, and i am trying to keep things somewhat compact, i am hoping to get it down to 60 liters but i may have to settle for 90 liters internal depending on how some of the next few experiments measure up ....
Another issue i am having is the fact that the Dayton PA-310 is an efficient woofer in the midrange frequencies and if i lose efficiency on the bottom end (due to a lower tuning or anything else) the midrange will easily outrun the bass range and it sounds too thin and mid-aggressive to me (NOTE: I have found that it can also sound terribly midrange-dominant and anemic to me if i remove the K-aperture's wings which eliminates the design's front chamber turning it into a direct radiating offset-driver-ML-TL and it sounds thin to the point of being repulsive set up that way, but that's not related to the FB, this box just seems to require a front chamber in order to sound pleasant) ......
Originally a strictly subwoofer application was what i had intended for this 6th order bandpass design but when it became apparent that much more bandwidth could be achieved i had to strive for it with the gentle urging and guidance of some of the respectable gentleman on these forums 🙂 It turns out that this Dayton driver will be carrying everything from around 40hz all the way up to 2000hz which really turns this project into a balancing act if i want things to sound good without employing the use of an equalizer or electronic bass-boost, so because of this challenge i think i would rather miss the target by ending up a few Hertz higher than 40, (rather than a few Hertz low) just for the sake of tonal balance...
😀
Zero D ,
Yes, exactly right, that cardboard did flex and moved a little too much, the duct tape i used provided a nice seal though, so i went ahead and placed some scrap ply over the front of the cardboard and then clamped it in place which seems to work 🙂
About the 3hz: this is just a prototype box, and i am just working out what fine adjustments to the design will need to be made in order to approach a 40hz extension with enough output to be useful as a small and highly portable PA system ... So why 40hz? .... The driver (A Dayton Pa-310) has a limited XMAX figure so it was never really meant to be a low-tuned subwoofer, although someone could use it that way in the right cabinet (if they really wanted to) it is just not ideal because the driver's modest excursion capabilities would severely limit the maximum output levels ... 40hz seems like a reasonable balance of extension and output and is fine for reproducing most modern music .....
Tuning lower also means that you lose some bottom-end efficiency unless you are willing to increase the size of the box, and i am trying to keep things somewhat compact, i am hoping to get it down to 60 liters but i may have to settle for 90 liters internal depending on how some of the next few experiments measure up ....
Another issue i am having is the fact that the Dayton PA-310 is an efficient woofer in the midrange frequencies and if i lose efficiency on the bottom end (due to a lower tuning or anything else) the midrange will easily outrun the bass range and it sounds too thin and mid-aggressive to me (NOTE: I have found that it can also sound terribly midrange-dominant and anemic to me if i remove the K-aperture's wings which eliminates the design's front chamber turning it into a direct radiating offset-driver-ML-TL and it sounds thin to the point of being repulsive set up that way, but that's not related to the FB, this box just seems to require a front chamber in order to sound pleasant) ......
Originally a strictly subwoofer application was what i had intended for this 6th order bandpass design but when it became apparent that much more bandwidth could be achieved i had to strive for it with the gentle urging and guidance of some of the respectable gentleman on these forums 🙂 It turns out that this Dayton driver will be carrying everything from around 40hz all the way up to 2000hz which really turns this project into a balancing act if i want things to sound good without employing the use of an equalizer or electronic bass-boost, so because of this challenge i think i would rather miss the target by ending up a few Hertz higher than 40, (rather than a few Hertz low) just for the sake of tonal balance
... 😀
Intrigue and mystery! Karlson Mystique!
Freddi ,
The fact that it could sound so entirely different by ear yet not look significantly different in the measurements is fascinating! What do you suppose was going on there? A relationship between phase and frequency? Is it possible that the phase response would look noticeably different?
I suspect that your "one-off" K-cab for the 18 (with the smaller gap at the top of the slot) is much like this Karlflex because it also needs the smaller gap (or in this case i covered up the gap) in order to balance the mids properly .... A little more presence in the midbass is just what it needed, and it could even be taken a little further without sounding muffled, congested or muddy but i can't make the gap any narrower than closed 😛 , so i guess this is it, and i can live with that ...🙂
Freddi ,
The fact that it could sound so entirely different by ear yet not look significantly different in the measurements is fascinating! What do you suppose was going on there? A relationship between phase and frequency? Is it possible that the phase response would look noticeably different?
I suspect that your "one-off" K-cab for the 18 (with the smaller gap at the top of the slot) is much like this Karlflex because it also needs the smaller gap (or in this case i covered up the gap) in order to balance the mids properly .... A little more presence in the midbass is just what it needed, and it could even be taken a little further without sounding muffled, congested or muddy but i can't make the gap any narrower than closed 😛 , so i guess this is it, and i can live with that ...🙂
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I don't know why it sounded so much different - maybe its like the time honored practice of drilling holes in a skull to let out the demons 😀
(btw- Karlson's X15 sometime used de-Q-ing holes flanking the vent - can make transients sound "faster")
although not like jazz soloing , Clarke has some real skill and imo its better sonically and musically than the old Sheffield disk - it should be worth your price sans shipping 🙂
(btw- Karlson's X15 sometime used de-Q-ing holes flanking the vent - can make transients sound "faster")
although not like jazz soloing , Clarke has some real skill and imo its better sonically and musically than the old Sheffield disk - it should be worth your price sans shipping 🙂
MMJ - have you drawn up the smaller K-flex? - if PA310 has nice mids then I might like one with an internal K-tube/compression driver (if that will fit so the tube's nose sits in the main aperture)
Final details and stuff, doing some listening tests
Hi Freddi!
It is so synchronous that you brought that up because I was just thinking tonight about how i should revise the sketch to include all of the recent changes .....
A few days ago i decided to again alter the upper part of the K-slot (which i had previously closed off) , instead i cut a narrow slit in the cardboard to make a narrow "cusp" shaped K-slot (like what you and X had both suggested) ..... The area in front of the driver's cone is still not obscured (which makes it conveniently easy to remove the driver without any need to remove the Aperture's wings)...... This narrow slot gap which starts as 1" wide just above the driver and comes to a point at the top is no more than 11 or 12 inches tall (above the driver) before reaching the top of the cabinet on a 24 inch Karlflex (it is about 13" on this prototype box which is 27" tall if i do not include the experimental parasitic chamber at the bottom of the cab)......
So over the last few days i have been doing some listening tests with this narrow K-slot contour (narrow slot above driver) and it certainly sounds a heck of a lot different than the old 2.75" width slot which sounded thin and the mids were relatively aggressive and screamy-hot on some tracks....... Of course i also recently tried closing off the slot gap altogether resulting in a considerably thickened and warmer sound compared to the old slot and i liked the new sound however i think that this narrow slot shape sounds very similar..
I tried covering up this narrow slot with a piece of ply numerous times while listening to music in an attempt to hear a difference between the slotted front chamber and non-slotted front chamber ( leaving the main terminus/mouth opening directly in front of the driver exactly the same for both tests) , and it is difficult for me to discern any difference, however i am getting the impression that the narrow slot produces a marginally more lively and dynamic lower-mid sound and possibly has a little more presence in that range which i like 🙂........ I am going to test this again from across the room while i have someone repeatedly cover the slot during various music selections to see if the difference is more apparent at a distance ...
Oddly enough i don't notice a lot of air being thrust through the top of the K-slot with kick drums or any other loud bass sounds whether transient/impulse or otherwise, i will have to try again at a higher volume but so far it looks like i might not have any problems with chuffing sounds (even when Akabak said it would definitely be a problem with aperture slots that are so narrow near the top) .....
I am sure this slot raised FB to some extent but i haven't tested for that just yet .. .
Steve Clarke drum solo CD is on it's way 🙂
Freddi, i am sure that a little K-tube compression driver combo would work for this Karlflex , a compression driver that can produce a reasonably flat 95-99db @1w-1m and can provide support down to 2k should do the trick ......
I also started to look into what other 12" drivers could produce as much useful bandwidth as the PA-310 in this cabinet and it turns out that the Eminence Kappalite 3012lf is an excellent candidate for someone who wants additional output thanks to the nearly doubled xmax rating.. Unfortunately the 3012lf also costs about three times as much as the Dayton but that option might still appeal to some people .... In my opinion (regarding value) the Dayton PA-310 is still the best bargain..
Hi Freddi!
It is so synchronous that you brought that up because I was just thinking tonight about how i should revise the sketch to include all of the recent changes .....
A few days ago i decided to again alter the upper part of the K-slot (which i had previously closed off) , instead i cut a narrow slit in the cardboard to make a narrow "cusp" shaped K-slot (like what you and X had both suggested) ..... The area in front of the driver's cone is still not obscured (which makes it conveniently easy to remove the driver without any need to remove the Aperture's wings)...... This narrow slot gap which starts as 1" wide just above the driver and comes to a point at the top is no more than 11 or 12 inches tall (above the driver) before reaching the top of the cabinet on a 24 inch Karlflex (it is about 13" on this prototype box which is 27" tall if i do not include the experimental parasitic chamber at the bottom of the cab)......
So over the last few days i have been doing some listening tests with this narrow K-slot contour (narrow slot above driver) and it certainly sounds a heck of a lot different than the old 2.75" width slot which sounded thin and the mids were relatively aggressive and screamy-hot on some tracks....... Of course i also recently tried closing off the slot gap altogether resulting in a considerably thickened and warmer sound compared to the old slot and i liked the new sound however i think that this narrow slot shape sounds very similar..
I tried covering up this narrow slot with a piece of ply numerous times while listening to music in an attempt to hear a difference between the slotted front chamber and non-slotted front chamber ( leaving the main terminus/mouth opening directly in front of the driver exactly the same for both tests) , and it is difficult for me to discern any difference, however i am getting the impression that the narrow slot produces a marginally more lively and dynamic lower-mid sound and possibly has a little more presence in that range which i like 🙂........ I am going to test this again from across the room while i have someone repeatedly cover the slot during various music selections to see if the difference is more apparent at a distance ...
Oddly enough i don't notice a lot of air being thrust through the top of the K-slot with kick drums or any other loud bass sounds whether transient/impulse or otherwise, i will have to try again at a higher volume but so far it looks like i might not have any problems with chuffing sounds (even when Akabak said it would definitely be a problem with aperture slots that are so narrow near the top) .....
I am sure this slot raised FB to some extent but i haven't tested for that just yet .. .
Steve Clarke drum solo CD is on it's way 🙂
Freddi, i am sure that a little K-tube compression driver combo would work for this Karlflex , a compression driver that can produce a reasonably flat 95-99db @1w-1m and can provide support down to 2k should do the trick ......
I also started to look into what other 12" drivers could produce as much useful bandwidth as the PA-310 in this cabinet and it turns out that the Eminence Kappalite 3012lf is an excellent candidate for someone who wants additional output thanks to the nearly doubled xmax rating.. Unfortunately the 3012lf also costs about three times as much as the Dayton but that option might still appeal to some people .... In my opinion (regarding value) the Dayton PA-310 is still the best bargain..
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Hi, I have been following this thread with great interest. Love when old ideas is taken to new heights. I've found this driver http://www.bluearan.co.uk/sales/faital_pro/15FH510_datasheet_8.pdf and it seems to fit the project perfect. High BL 21, x-max 9,25mm, high sensitivity 98db. For 157 euro = 175 $ it is a fair deal in my opinion.
My problem is that I can't simulate in akabak only hornresp. And the newest iterations is simulated in akabak. I would like a frequency response from 35 to 500hz. Hope some can help point out the right box model for this driver and suggestions for aperture.
A big thanx should go out to Mr. Matthew Morgan for taken the time to do all this work and infuse others including me, with great inspiration, thanx.
View attachment 15FH510_datasheet_8.pdf
Regards Sebastian
My problem is that I can't simulate in akabak only hornresp. And the newest iterations is simulated in akabak. I would like a frequency response from 35 to 500hz. Hope some can help point out the right box model for this driver and suggestions for aperture.
A big thanx should go out to Mr. Matthew Morgan for taken the time to do all this work and infuse others including me, with great inspiration, thanx.
View attachment 15FH510_datasheet_8.pdf
Regards Sebastian
Hi schlager,
That is: 157 £ = 213.65 € = 238.16 $
And for less money, 156 € 🙂, you can buy for instance a decent P.Audio 18" IMF-HP18B driver...
Cheers,
Djim
Eminence :: Eminence Kappa Pro 15 LF C 15" 600W 4 Ohm Loudspeaker Driver Twin Pack 276.34
7.9mm, two for £276.34 (£138.17 each in pairs)
7.9mm, two for £276.34 (£138.17 each in pairs)
You are perfectly right, pounds not euro, my bad 😱. Guess that plan went down the drain 😉 18" makes the box to wide but a good deal, nonetheless.
Cheers
Driver chat and ideas
Kappa12a might work, and i would imagine it would have a midrange dominant tonal quality because of it's very high efficiency (99db 1w/1m) combined with it's low QTS figure (.27) .......I cannot be sure if the bottom end would quite keep up with the mids in this case (unless EQ was used of course, but that would be cheating! 😛)............
The Dayton PA-310 has a combination of QTS=.34 and SPL=96db 1w/1m (Qts/Qes measured with the DATS, and the figure may decrease by a small amount after the driver is fully broken-in)..... With this combination i was struggling to get the bass and mids to balance out.... I finally managed to get the bottom end to keep pace with the midrange after changing the shape of the aperture, but i think that if this Dayton driver were any hotter in the midrange (or if it had a lower QTS) it would have been exceedingly difficult to achieve an acceptable tonal balance unless the box was tuned higher or the front chamber was made larger or some other drastic change made to the cabinet .....
With pro 15" drivers and 18" drivers (in scaled up Karlflex cabs) i think that a satisfying tonal balance would be relatively easy to achieve (compared to a high efficiency 12) ..
NOTE: For folks that are following this discussion, i think many people have a misconception about low QTS figures strictly equating to a strong motor, but that is not necessarily true, a low QTS can sometimes just be the result of a light moving mass and a very loose suspension (or in other words a high VAS figure) which is not ideal in this alignment.......... If i could build an ideal driver for the Karlflex it would (referring to the Pa-310 as an example) possess a much stiffer suspension (lower VAS), stronger motor and a QTS/QES in the .4 to .5 range with a high QMS figure, this would of course drive the FS (free-air resonance) of the driver upward but that is fine, a quarter-wave (eigenmode) based design like this box allows a driver to play below FS, no problem at all ........
Currently the Dayton is selling for about $67 and in that low price range it looks like the PA-310 is about as close to ideal for this box as it gets, if anyone is able to find anything more ideal for around the same price please let me know so i can add it to the budget driver list when i make the new sketch.......
So hey Freddi ! I have an idea!,
Speaking of drivers i think there might be an alternative strategy worth taking into consideration since you personally aren't really aiming for deep bass extension.... Your preference makes finding the right driver easier because it opens up some affordable options with different parameters that will compromise 40hz output in order to get some decent gains in the 65hz-150hz range ...... For example the Eminence Beta12a2 has very little output at 40hz in this small Karlflex cab but starts to provide good support around 55hz with a nice big bump in response between 65hz and 150hz (a curve that looks more like it belongs to a Classic Carlson cabinet! and the useful response will carry out to at least 2khz as long as the driver is capable of that) 😀 .... Let me know what you think of this idea Freddi 🙂
Kappa12a might work, and i would imagine it would have a midrange dominant tonal quality because of it's very high efficiency (99db 1w/1m) combined with it's low QTS figure (.27) .......I cannot be sure if the bottom end would quite keep up with the mids in this case (unless EQ was used of course, but that would be cheating! 😛)............
The Dayton PA-310 has a combination of QTS=.34 and SPL=96db 1w/1m (Qts/Qes measured with the DATS, and the figure may decrease by a small amount after the driver is fully broken-in)..... With this combination i was struggling to get the bass and mids to balance out.... I finally managed to get the bottom end to keep pace with the midrange after changing the shape of the aperture, but i think that if this Dayton driver were any hotter in the midrange (or if it had a lower QTS) it would have been exceedingly difficult to achieve an acceptable tonal balance unless the box was tuned higher or the front chamber was made larger or some other drastic change made to the cabinet .....
With pro 15" drivers and 18" drivers (in scaled up Karlflex cabs) i think that a satisfying tonal balance would be relatively easy to achieve (compared to a high efficiency 12) ..
NOTE: For folks that are following this discussion, i think many people have a misconception about low QTS figures strictly equating to a strong motor, but that is not necessarily true, a low QTS can sometimes just be the result of a light moving mass and a very loose suspension (or in other words a high VAS figure) which is not ideal in this alignment.......... If i could build an ideal driver for the Karlflex it would (referring to the Pa-310 as an example) possess a much stiffer suspension (lower VAS), stronger motor and a QTS/QES in the .4 to .5 range with a high QMS figure, this would of course drive the FS (free-air resonance) of the driver upward but that is fine, a quarter-wave (eigenmode) based design like this box allows a driver to play below FS, no problem at all ........
Currently the Dayton is selling for about $67 and in that low price range it looks like the PA-310 is about as close to ideal for this box as it gets, if anyone is able to find anything more ideal for around the same price please let me know so i can add it to the budget driver list when i make the new sketch.......
So hey Freddi ! I have an idea!,
Speaking of drivers i think there might be an alternative strategy worth taking into consideration since you personally aren't really aiming for deep bass extension.... Your preference makes finding the right driver easier because it opens up some affordable options with different parameters that will compromise 40hz output in order to get some decent gains in the 65hz-150hz range ...... For example the Eminence Beta12a2 has very little output at 40hz in this small Karlflex cab but starts to provide good support around 55hz with a nice big bump in response between 65hz and 150hz (a curve that looks more like it belongs to a Classic Carlson cabinet! and the useful response will carry out to at least 2khz as long as the driver is capable of that) 😀 .... Let me know what you think of this idea Freddi 🙂
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