New combinations of old ideas =) More listening tests have been performed
GM,
Yessir, i have been told that the technique of using these sorts of tuned chambers and pipes to smooth response has been around for a very long time ....... I really appreciate Freddy's idea not for the device itself alone necessarily, but especially for the specific PLACEMENT of his tuned cavity in a Karlson-style system, because not only is it effective for what it was originally intended (verified now that i built it) but this placement also seems to have other benefits such as effectively increasing the size of the front chamber (also verified by a significant downward shift in front chamber resonance in the real world model), and also helps by smoothing out the upper resonant response of the front chamber and reducing some of the obnoxious ringing reverberant resonances i was hearing in the midbass and midrange before adding the mod, Freddy's mod provides all of these benefits along with performing it's original intended purpose of taming the upper harmonics of the main pipe path (these particular harmonics were previously causing problems between 180hz and 300hz) ........
So i guess what i am saying here is that the idea of the tuned cavity itself is nothing new, but it's placement (Freddi's idea from one of his sketches) is absolutely brilliant!
It has really made very wideband operation possible with this Karflex which is essentially a type of 6th order "bandpass cabinet" , but with the appropriate drivers like the PA-310 the response extends far beyond any typical bandpass box ..... Many of the other drivers that i had in mind when designing this cab are strictly sub drivers and would be limited to around 200 to 250hz on the high end, the Dayton on the other hand may reach upwards of 1k of useful response using the K-slot type aperture ....
I have been doing lots of listening tests just using this simple clamped on plank aperture, originally this box was fatiguing to listen to before the Freddi mod, and now after the mod it sounds so much smoother, tighter and pleasant to listen to
huge improvement ..
Next step will be to make the K-slot and take some measurements and do some listening with that , it requires working outside for a bit though which is currently unpleasant with our 110+ degree heat we have been experiencing here lately in the Phoenix area, so i guess i am just avoiding that heat and progress has slowed down
After some thorough testing with the K-slot the next step will be to build a wide Karflex (without the Labyrinthine parasitic chamber) but including the Freddi-Mod for these Daytons , then i will consider this mini PA speaker project finally complete ..... I would then also release some updated detailed sketches including the new tuned cavity mod .....
GM,
Yessir, i have been told that the technique of using these sorts of tuned chambers and pipes to smooth response has been around for a very long time ....... I really appreciate Freddy's idea not for the device itself alone necessarily, but especially for the specific PLACEMENT of his tuned cavity in a Karlson-style system, because not only is it effective for what it was originally intended (verified now that i built it) but this placement also seems to have other benefits such as effectively increasing the size of the front chamber (also verified by a significant downward shift in front chamber resonance in the real world model), and also helps by smoothing out the upper resonant response of the front chamber and reducing some of the obnoxious ringing reverberant resonances i was hearing in the midbass and midrange before adding the mod, Freddy's mod provides all of these benefits along with performing it's original intended purpose of taming the upper harmonics of the main pipe path (these particular harmonics were previously causing problems between 180hz and 300hz) ........
So i guess what i am saying here is that the idea of the tuned cavity itself is nothing new, but it's placement (Freddi's idea from one of his sketches) is absolutely brilliant!
It has really made very wideband operation possible with this Karflex which is essentially a type of 6th order "bandpass cabinet" , but with the appropriate drivers like the PA-310 the response extends far beyond any typical bandpass box ..... Many of the other drivers that i had in mind when designing this cab are strictly sub drivers and would be limited to around 200 to 250hz on the high end, the Dayton on the other hand may reach upwards of 1k of useful response using the K-slot type aperture ....
I have been doing lots of listening tests just using this simple clamped on plank aperture, originally this box was fatiguing to listen to before the Freddi mod, and now after the mod it sounds so much smoother, tighter and pleasant to listen to
huge improvement ..Next step will be to make the K-slot and take some measurements and do some listening with that , it requires working outside for a bit though which is currently unpleasant with our 110+ degree heat we have been experiencing here lately in the Phoenix area, so i guess i am just avoiding that heat and progress has slowed down
After some thorough testing with the K-slot the next step will be to build a wide Karflex (without the Labyrinthine parasitic chamber) but including the Freddi-Mod for these Daytons , then i will consider this mini PA speaker project finally complete ..... I would then also release some updated detailed sketches including the new tuned cavity mod .....
Noteworthy observations and exciting projects for the future!Start a new discussion?
NOTE: Even though i will go without the parasitic chamber/labyrinth section on the next more simple Karlflex builds i have to say there is something intriguing going on with this labyrinthine parasitic chamber, it is producing some amount of deep resonances that are well below the current FB impedance minimum of 40hz , those lower resonances are not loud necessarily but they are there, and cone control is actually pretty good down to 32hz ......... This is very reminiscent of an enigmatic TL-DCR that we built for a friend ( the design was another one of my experimental spinoffs of the Augsperger-Weems method adapted to pipe resonances instead of Helmholtz) ... These were MTM towers tuned to a 75hz fundamental with a parasitic pipe resonance of 125hz for the second section, these towers were to be used with a friend's home theater system as his front mains channels .... The little midbass drivers we used had high QTS/QES figures and very high FS (free-air resonances) of around 100hz, yet this cabinet (tuned to 75hz , ) gave solid response right down to 58hz with equally fantastic cone control! The cones barely moved actually even while producing a significant amount of full range sound and rich bass (the tests were performed with an unfiltered signal), we were more than pleasantly surprised, we were fully astonished and frankly a little bit baffled by the results, that was over a year ago ....... I would like to design another cabinet with similar characteristics (like the prominent strange below-fb resonance and below-fb support) but scaled up and tuned lower than my friend's towers to provide decent useful response down to 40hz, so i am figuring that a tuning of 50hz would do the trick since cone support and output seemed to be solid and useful to around 80% of the FB in the original experimental home theater towers....... The higher tuning in such a design would provide a significant savings of excursion, higher effiiciency , as well as increased power handling, therefore much improved output for all of these reasons ..... This concept is exciting to me and if i can prove that it works it will definitely be worthy of starting an entirely new conversation, the only problems i foresee are possibly a difficulty finding an appropriate driver (will the very high driver QES/QTS and high FS be essentially required to make this work?? I hope not ..... Hard to say since the simulators do not model the mysterious bonus extension in this alignment properly, maybe i will try with a PA310 first to see what happens) ......ANYHOW...... This is all for the future, in the meantime i have to finish up this Karlflex project ...
NOTE: Even though i will go without the parasitic chamber/labyrinth section on the next more simple Karlflex builds i have to say there is something intriguing going on with this labyrinthine parasitic chamber, it is producing some amount of deep resonances that are well below the current FB impedance minimum of 40hz , those lower resonances are not loud necessarily but they are there, and cone control is actually pretty good down to 32hz ......... This is very reminiscent of an enigmatic TL-DCR that we built for a friend ( the design was another one of my experimental spinoffs of the Augsperger-Weems method adapted to pipe resonances instead of Helmholtz) ... These were MTM towers tuned to a 75hz fundamental with a parasitic pipe resonance of 125hz for the second section, these towers were to be used with a friend's home theater system as his front mains channels .... The little midbass drivers we used had high QTS/QES figures and very high FS (free-air resonances) of around 100hz, yet this cabinet (tuned to 75hz , ) gave solid response right down to 58hz with equally fantastic cone control! The cones barely moved actually even while producing a significant amount of full range sound and rich bass (the tests were performed with an unfiltered signal), we were more than pleasantly surprised, we were fully astonished and frankly a little bit baffled by the results, that was over a year ago ....... I would like to design another cabinet with similar characteristics (like the prominent strange below-fb resonance and below-fb support) but scaled up and tuned lower than my friend's towers to provide decent useful response down to 40hz, so i am figuring that a tuning of 50hz would do the trick since cone support and output seemed to be solid and useful to around 80% of the FB in the original experimental home theater towers....... The higher tuning in such a design would provide a significant savings of excursion, higher effiiciency , as well as increased power handling, therefore much improved output for all of these reasons ..... This concept is exciting to me and if i can prove that it works it will definitely be worthy of starting an entirely new conversation, the only problems i foresee are possibly a difficulty finding an appropriate driver (will the very high driver QES/QTS and high FS be essentially required to make this work?? I hope not ..... Hard to say since the simulators do not model the mysterious bonus extension in this alignment properly, maybe i will try with a PA310 first to see what happens) ......ANYHOW...... This is all for the future, in the meantime i have to finish up this Karlflex project ...
Hmm, don't currently have access to my notes from way back when we discussed it, but from dim memory he learned it from others, but could be wrong. Regardless, he proofed it quite awhile back and as you've found out, like most paths through life it's all about location, location, location, so now with proper software it can be further fine tuned and expanded upon.
GM
I am sold
Gm ,
You are right about location and it's importance, ever consider a career in Real Estate? hehe
I was unable to figure out how to implement such a thing in Hornresp but i did work out some scripts in Akabak that look great, and the real-world built version matched the Akabak simulated response very closely so i am very happy about that ..
In post #1331 i posted the results of a few Karlflex sims in Akabak both with and without Freddi's proposed mod (these sim comparisons looked like such an improvement that they motivated me to build the cavity right on top of an already constructed Karlflex prototype to test this idea) :
http://www.diyaudio.com/forums/subw...d-series-tuned-6th-order-134.html#post4336429
Gm ,
You are right about location and it's importance, ever consider a career in Real Estate? hehe
I was unable to figure out how to implement such a thing in Hornresp but i did work out some scripts in Akabak that look great, and the real-world built version matched the Akabak simulated response very closely so i am very happy about that
.. In post #1331 i posted the results of a few Karlflex sims in Akabak both with and without Freddi's proposed mod (these sim comparisons looked like such an improvement that they motivated me to build the cavity right on top of an already constructed Karlflex prototype to test this idea) :
http://www.diyaudio.com/forums/subw...d-series-tuned-6th-order-134.html#post4336429
Not really, though we did fairly well in our youth with rentals until the justice system made it where the renter had more rights than the land owners, though we did turn a tidy profit in the '70s 'seller' market. Nowadays it's just too much hassle to waste my waning years on.
Yeah, over time, HR has become a pretty powerful program, but for specialized alignments, AkAbak, AJhorn are the only consumer available programs I know of and I forget the name now, but there was/is? an intake/exhaust system designer for several thousands that's the ultimate.
GM
Yeah, over time, HR has become a pretty powerful program, but for specialized alignments, AkAbak, AJhorn are the only consumer available programs I know of and I forget the name now, but there was/is? an intake/exhaust system designer for several thousands that's the ultimate.
GM
Hi Y'all,
I haven't found the time to play w/ ABEC yet, but I've heard good things about ABEC. I guess it's from the same gentlemen who created AkAbak, there is a free demo version, and also a student license for non-commercial use:
ABEC3
R&D-Team - Products
I think xrk971 has already looked into it?
Regards,
I haven't found the time to play w/ ABEC yet, but I've heard good things about ABEC. I guess it's from the same gentlemen who created AkAbak, there is a free demo version, and also a student license for non-commercial use:
ABEC3
R&D-Team - Products
I think xrk971 has already looked into it?
Regards,
Yes, very nice package but is completely different in that it is 3d finite element solver. It does have a lumped element solver (akabak core) somewhere but I played in the demo mode for a day or two. Looks very powerful for things like a waveguide or horn or a K aperture/lens. For multi route ducts and chambers akabak will get you the answer faster.
GM , TB46 , XRK ,
Is ABEC the one used to design intake/exhaust systems?
GM,
The rental biz eh? Neat! but yeah i bet it was a hassle at times .....
I live in a state with courts that have a notoriously landlord-friendly bias when deciding disputes which i'm sure must have a low-risk sort of appeal to people who buy up properties for usage as rentals...
Is ABEC the one used to design intake/exhaust systems?
GM,
The rental biz eh? Neat! but yeah i bet it was a hassle at times .....
I live in a state with courts that have a notoriously landlord-friendly bias when deciding disputes which i'm sure must have a low-risk sort of appeal to people who buy up properties for usage as rentals...
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I don't know anything about intake and exhaust systems. Are you guys talking about how modern sports cars use active tuning of intake manifold and exhaust pipes with butterfly valves and passive radiators to pipe throaty sports car sounds into the cockpit? I think Porsche and BMW do this.
If they do, I think the software would be COMSOL Multiphysics. $25k for the package. Typical price for commercial quality CAD/analysis software. I have seen a couple of guys use COMSOL here - Cookiemonster I think and someone else.
If they do, I think the software would be COMSOL Multiphysics. $25k for the package. Typical price for commercial quality CAD/analysis software. I have seen a couple of guys use COMSOL here - Cookiemonster I think and someone else.
XRK ,
I am really glad that you like it!
Has high quality high efficiency amplification ever been this affordable?? This set is one heck of a value!
You are running it at 8 ohms right now? Do you suppose it could operate at 4 ohms per channel for 400w total output with the single supply, or would a person need to use a two separate supplies in that case? (one supply per amplifier board) ....... I was looking at the PDF for that power supply recently trying to figure it out and as far as i can tell it should be able to pull it off as long as a person's music is dynamic and not just full scale sines for 5+ minutes straight
So all in all it could potentially be 400w output at less than 60 dollars or less than 15 cents a watt for some high quality class D amplification
I see the guys in the other discussion about this set (in the class D forum) seeming a little skeptical about this power supply, almost as if they think it is too good to be true or something, and so instead are suggesting the other brand which costs three times as much .... Screw the naysayers!If this supply holds up you have the deal of the century!
Not to ruin your hopes but a friend of mine bench tested that power supply and RMS power is close to 100W, still a great deal but the specs are quite off. YMMV.
X,
I don't know anything about intake or exhaust systems either, i was just asking because i was curious ..... Some guy said something about it earlier , and i think his name started with the letters GM
.... hehe
Sabaspeed , Xrk
Sabaspeed!
Hello !
Long time no see!
Yes, about that surplus Abletec power supply, i had seen someone else say the exact same thing in the "200w IRS2092" discussion that XRK started in the Class D forum .... The guy he said he bought a few quite a while ago, tested them and was able to draw up to 100 watts out of them before some sort of overcurrent foldback occurred .....If i remember correctly he said it never got hot at all, it just cut out early.... (i hope i didn't butcher his statements too badly)..
I guess the big question is whether the currently available surplus Abletecs still have that exact same flaw .... If so that would explain the outrageously low price ...
I think XRK was talking about setting those amps up on some sort of dummy load or something so he could do more testing ...
@ XRK ,
Have you had a chance to really push those amps yet to see if the supply holds up well?
Sabaspeed!
Hello !
Long time no see!
Yes, about that surplus Abletec power supply, i had seen someone else say the exact same thing in the "200w IRS2092" discussion that XRK started in the Class D forum .... The guy he said he bought a few quite a while ago, tested them and was able to draw up to 100 watts out of them before some sort of overcurrent foldback occurred .....If i remember correctly he said it never got hot at all, it just cut out early.... (i hope i didn't butcher his statements too badly)..
I guess the big question is whether the currently available surplus Abletecs still have that exact same flaw .... If so that would explain the outrageously low price ...
I think XRK was talking about setting those amps up on some sort of dummy load or something so he could do more testing ...
@ XRK ,
Have you had a chance to really push those amps yet to see if the supply holds up well?
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Not yet, looking for a 4 to 12ohm 1kW hot plate as dummy resistor. The ps spec sheet says it can do 900w momentarily and 450w sustained. Although ps needs to be bolted to heat sink to do so. So a few more items needed before doing the manly man power test.
IFF it holds up to 450w sustained then $20 is the deal of the century.
IFF it holds up to 450w sustained then $20 is the deal of the century.
*crosses fingers*
Not yet, looking for a 4 to 12ohm 1kW hot plate as dummy resistor. The ps spec sheet says it can do 900w momentarily and 450w sustained. Although ps needs to be bolted to heat sink to do so. So a few more items needed before doing the manly man power test.
IFF it holds up to 450w sustained then $20 is the deal of the century.
Perhaps something useful going on here
Ok , I have a K-slot on the Karlflex now and the results are very good , but before moving on to that i want to say something about the strange phenomenon mentioned in post #1382
http://www.diyaudio.com/forums/subw...d-series-tuned-6th-order-139.html#post4367436
Upon some more contemplation and looking over the impedance graphs and response graphs i am now under the impression that with these Augsperger-Weems TL adapted parasitic chamber designs it is possible to not only develop a new resonance above the fundamental (which is the whole idea behind a DCR) but ALSO there is some other resonance generated below fundamental that can be very prominent and useful as in my friend's DC-TL towers (which used a parasitic section made out of an offset vented pipe , a quasi-halfwave approach, which produced a strong useful resonance at about 80% of the fundamental, improving it's bass extension and cone control dramatically), versus the labyrinthine parasitic section design used in my prototype Karlflex which did not generate enough resonance below the fundamental to be useful in this regard , so i may try to redesign a cabinet for the PA-310 based upon a parasitic section like we used in the DC-TL towers, but scaled up some for a lower tuning .....
Nevertheless , what should we call this strange sub-fundamental resonance? An aperiodic resonance? Phantom resonance? hmmm ...
You can see evidence of it in the DC-TL tower's impedance measurements ..... The lower impedance peak is somewhat subdued (compared to the upper impedance peak) and you can see a tiny dip at 59hz (well below the fundamental of 75hz) indicating that there may be some extra resonance centered around 58hz but it is spread out enough to mellow out the impedance peak in that region somewhat , once again indicates some sort of loading and also allows more power to be delivered to the driver down there ...
If i can figure out how to optimize this effect it could be used as a method for cheating Hoffman's Iron law to some extent , and that is why i find this exciting! (this DC-TL box has a fundamental of 75hz but had strong output down to 60hz) ....
Then (below) is the Impedance measurement for the prototype Karlflex with Labyrinthine parasitic section .... You can see how i missed the mark here with the upper peak being more suppressed than the lower peak , and there was not enough useful resonance below FB to improve the bass extension......
I need to redesign this with a parasitic pipe section driven in an offset fashion (by the interchamber vent) just like we used in the DC-TL , and that way i could potentially tune the box's fundamental to 50hz and still get great output and cone control down to 40hz while still retaining all of the benefits of the higher tune! (such as better power handling, better efficiency, less path length required, improved cone control in the 45hz-70hz range etc)
Anyhow, i won't muddy the waters any further by ranting about this weirdness in this particular discussion, if i can build another box and get this to work properly again then i will start an entirely new discussion about this method ...
Ok , I have a K-slot on the Karlflex now and the results are very good , but before moving on to that i want to say something about the strange phenomenon mentioned in post #1382
http://www.diyaudio.com/forums/subw...d-series-tuned-6th-order-139.html#post4367436
Upon some more contemplation and looking over the impedance graphs and response graphs i am now under the impression that with these Augsperger-Weems TL adapted parasitic chamber designs it is possible to not only develop a new resonance above the fundamental (which is the whole idea behind a DCR) but ALSO there is some other resonance generated below fundamental that can be very prominent and useful as in my friend's DC-TL towers (which used a parasitic section made out of an offset vented pipe , a quasi-halfwave approach, which produced a strong useful resonance at about 80% of the fundamental, improving it's bass extension and cone control dramatically), versus the labyrinthine parasitic section design used in my prototype Karlflex which did not generate enough resonance below the fundamental to be useful in this regard , so i may try to redesign a cabinet for the PA-310 based upon a parasitic section like we used in the DC-TL towers, but scaled up some for a lower tuning .....
Nevertheless , what should we call this strange sub-fundamental resonance? An aperiodic resonance? Phantom resonance?
hmmm ...You can see evidence of it in the DC-TL tower's impedance measurements ..... The lower impedance peak is somewhat subdued (compared to the upper impedance peak) and you can see a tiny dip at 59hz (well below the fundamental of 75hz) indicating that there may be some extra resonance centered around 58hz but it is spread out enough to mellow out the impedance peak in that region somewhat , once again indicates some sort of loading and also allows more power to be delivered to the driver down there
... If i can figure out how to optimize this effect it could be used as a method for cheating Hoffman's Iron law to some extent , and that is why i find this exciting! (this DC-TL box has a fundamental of 75hz but had strong output down to 60hz) ....
An externally hosted image should be here but it was not working when we last tested it.
Then (below) is the Impedance measurement for the prototype Karlflex with Labyrinthine parasitic section .... You can see how i missed the mark here with the upper peak being more suppressed than the lower peak , and there was not enough useful resonance below FB to improve the bass extension
...... I need to redesign this with a parasitic pipe section driven in an offset fashion (by the interchamber vent) just like we used in the DC-TL , and that way i could potentially tune the box's fundamental to 50hz and still get great output and cone control down to 40hz while still retaining all of the benefits of the higher tune! (such as better power handling, better efficiency, less path length required, improved cone control in the 45hz-70hz range etc)
An externally hosted image should be here but it was not working when we last tested it.
Anyhow, i won't muddy the waters any further by ranting about this weirdness in this particular discussion, if i can build another box and get this to work properly again then i will start an entirely new discussion about this method ...
K-SLOT APERTURE ON THE KARLFLEX PROTOTYPE!!
As a wise man once said :
"It resembles a giant wooden vagina" (and i would like to add) from which wonderful sounding music is given birth!!
This is a BIG improvement over that plank aperture i was using ..... Upper mids have really opened up and i think that cutoff at 500hz is alleviated or smoothed over, i cannot be sure until i get a measurement though, i just know it sounds much better ......... Vocals have just the right amount of warmth now and do not sound overly aggressive or muddy, all instruments are sitting in the mix properly.... The bottom end seems less stifled and has more presence ...... It is now more enjoyable to listen to overall, with a wider variety of music... Non fatiguing, some tracks even sounded so good that it was sort of "haunting" and immersive, I can live with this sound
As a wise man once said :
"It resembles a giant wooden vagina" (and i would like to add) from which wonderful sounding music is given birth!!
An externally hosted image should be here but it was not working when we last tested it.
This is a BIG improvement over that plank aperture i was using ..... Upper mids have really opened up and i think that cutoff at 500hz is alleviated or smoothed over, i cannot be sure until i get a measurement though, i just know it sounds much better ......... Vocals have just the right amount of warmth now and do not sound overly aggressive or muddy, all instruments are sitting in the mix properly.... The bottom end seems less stifled and has more presence ...... It is now more enjoyable to listen to overall, with a wider variety of music
... Non fatiguing, some tracks even sounded so good that it was sort of "haunting" and immersive, I can live with this sound
it is possible to not only develop a new resonance above the fundamental (which is the whole idea behind a DCR) but ALSO there is some other resonance generated below fundamental that can be very prominent and useful as in my friend's DC-TL towers.........
Nevertheless , what should we call this strange sub-fundamental resonance? An aperiodic resonance? Phantom resonance?
Driver specs?
GM
As a wise man once said :
"It resembles a giant wooden vagina" (and i would like to add) from which wonderful sounding music is given birth!!
An externally hosted image should be here but it was not working when we last tested it.
This is a BIG improvement over that plank aperture i was using ..... Upper mids have really opened up and i think that cutoff at 500hz is alleviated or smoothed over, i cannot be sure until i get a measurement though, i just know it sounds much better ......... Vocals have just the right amount of warmth now and do not sound overly aggressive or muddy, all instruments are sitting in the mix properly.... The bottom end seems less stifled and has more presence ...... It is now more enjoyable to listen to overall, with a wider variety of music
It sounds good and you don't even have a tweeter yet? Is that a PA310-8?
Nice work - round off the sharp angles to get a true K aperture and it will sound even better. Make the aperture go to zero a the top like a cusp and you will get more bass extension and a smoother response.
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