Hi,
Killjoy: The link to the Ciare 15" you modelled does not seems to work, and going on usspeaker.com the only Ciare 15" that is listed - Model 15.00SW - has considerabley different parameters. Must be a different model.
Anyhow, enclosed is the hornresp input and SPL for that speaker in your box dimensions. Obviously,it does not look smooth, but seems to be a good example to point out some of the tuning that may apply to the tapped horn in general:
1. Active high pass filter to prevent excessive cone deflection below the passband, and to control any low peaking (e.g.: in this case @ 21Hz),
2. Series passive filter element (L) to control the peaking @60Hz and to modify the speaker parameters. (As an aside, the Jensen Transflex paper recommended a 45hz 2nd order passive cross-over network.)
3. Tuned resonators to reduce the first few resonant peaks, maybe @ 94Hz, 150Hz, 235Hz, 330Hz.
4. Lining of parts of the horn walls to reduce the higher frequency hash.
I feel, that even if one does (obviously) a better job of speaker selection and box tuning, all of the above will apply to just about any tapped horn. Which, if nothing else, makes this quite a project to get right. This is really interesting.
Killjoy: The link to the Ciare 15" you modelled does not seems to work, and going on usspeaker.com the only Ciare 15" that is listed - Model 15.00SW - has considerabley different parameters. Must be a different model.
Anyhow, enclosed is the hornresp input and SPL for that speaker in your box dimensions. Obviously,it does not look smooth, but seems to be a good example to point out some of the tuning that may apply to the tapped horn in general:
1. Active high pass filter to prevent excessive cone deflection below the passband, and to control any low peaking (e.g.: in this case @ 21Hz),
2. Series passive filter element (L) to control the peaking @60Hz and to modify the speaker parameters. (As an aside, the Jensen Transflex paper recommended a 45hz 2nd order passive cross-over network.)
3. Tuned resonators to reduce the first few resonant peaks, maybe @ 94Hz, 150Hz, 235Hz, 330Hz.
4. Lining of parts of the horn walls to reduce the higher frequency hash.
I feel, that even if one does (obviously) a better job of speaker selection and box tuning, all of the above will apply to just about any tapped horn. Which, if nothing else, makes this quite a project to get right. This is really interesting.
Attachments
I dont think the peaks and nulls above the passband is such a big problem as Hornresp simulates. I cant hear any of the peaks as any kind of distortion when playing loud with my small tapped horn. If I realy had 10 dB higher efficiancy around the second and third harmonics of the bass coming out of the horn, it would sound terrible, but it dont. The bass is much cleaner and purer than any closed box/BR/BP i have ever heard. (of comparabel size)
Johannes.
Johannes.
@tb46: I have finally read the paper and it looks interesting, but for the moment I'll refrain from trying to model it in AkAbak. Since a TH Sub is mostly for a rather limited bandwidth I don't consider resonators an issue for extending the response.
I removed the "radiator" elements from my script above, as the only part that connects to the outside air is the mouth of the horn. (Why didn't I think of that earlier?)
The SPL plot is now what I would expect from a TH. The upper and lower knees of the passband are now clearly defined and the average sensitivity is as predicted in Hornresp.
However ... there is a broad dip over the passband that I don't have in the equivalent TH in hornresp. Since I'm using Hornresp as my reference, I'm wondering if this could be because of a difference in horn theory between AkAbak and Hornresp? Maybe someone can explain this?
for reference: here is my equivalent script in AkAbak:
-----------------------------------------------------------------
Def_Reflector TopCorner
Left=1.0m Top=1.0m Right=1.0m
HAngle=45.0°
Def_Driver 'SPH-212'
dD=21,2cm dD1=6,5cm tD1=2,5cm |Cone
fs=30Hz Vas=82L
Qms=2,21 Qes=0,5 Re=6,2ohm fre=8kHz Le=0.6mH
System 'RLDCTH'
Driver Def='SPH-212'
Node=1=0=200=300 |Driver connected to node 200 and 300
Duct 'FrontCompchamber'
Node=200=201 |driven by node 200 (front driver) and it drives/connects to node 201 (open end of resonator)
sD=0,206m2 Len=1cm Vf=0,1L
Duct 'Resonator' |80Hz one end closed resonator
Node=0=201 |def "resonator" with node 0 as closed end and connected to node 202
sD=0,206m2
Len=40cm
Waveguide 'Conical Horn'
Node=201=301 |Conical horn between nodes 201 and 301
STh=0,206m2 SMo=0,250m2
Len=300cm Conical
Duct 'BackCompchamber'
Node=300=301 |Driven by back of driver and drives/exits in the conical horn
sD=0,206m2 Len=1cm Vf=0,1L
Horn 'Endhorn'
Node=301 |Horn driven by node 301 (conical horn+output back comp chamber)
STh=0,250m2 SMo=1m2
Len=60cm T=1
x=0 y=0 z=0 HAngle=0 VAngle=0 dEdge=3m Reflection
---------------------------------------------------------------
With the SPL plot attached:
I removed the "radiator" elements from my script above, as the only part that connects to the outside air is the mouth of the horn. (Why didn't I think of that earlier?)
The SPL plot is now what I would expect from a TH. The upper and lower knees of the passband are now clearly defined and the average sensitivity is as predicted in Hornresp.
However ... there is a broad dip over the passband that I don't have in the equivalent TH in hornresp. Since I'm using Hornresp as my reference, I'm wondering if this could be because of a difference in horn theory between AkAbak and Hornresp? Maybe someone can explain this?
for reference: here is my equivalent script in AkAbak:
-----------------------------------------------------------------
Def_Reflector TopCorner
Left=1.0m Top=1.0m Right=1.0m
HAngle=45.0°
Def_Driver 'SPH-212'
dD=21,2cm dD1=6,5cm tD1=2,5cm |Cone
fs=30Hz Vas=82L
Qms=2,21 Qes=0,5 Re=6,2ohm fre=8kHz Le=0.6mH
System 'RLDCTH'
Driver Def='SPH-212'
Node=1=0=200=300 |Driver connected to node 200 and 300
Duct 'FrontCompchamber'
Node=200=201 |driven by node 200 (front driver) and it drives/connects to node 201 (open end of resonator)
sD=0,206m2 Len=1cm Vf=0,1L
Duct 'Resonator' |80Hz one end closed resonator
Node=0=201 |def "resonator" with node 0 as closed end and connected to node 202
sD=0,206m2
Len=40cm
Waveguide 'Conical Horn'
Node=201=301 |Conical horn between nodes 201 and 301
STh=0,206m2 SMo=0,250m2
Len=300cm Conical
Duct 'BackCompchamber'
Node=300=301 |Driven by back of driver and drives/exits in the conical horn
sD=0,206m2 Len=1cm Vf=0,1L
Horn 'Endhorn'
Node=301 |Horn driven by node 301 (conical horn+output back comp chamber)
STh=0,250m2 SMo=1m2
Len=60cm T=1
x=0 y=0 z=0 HAngle=0 VAngle=0 dEdge=3m Reflection
---------------------------------------------------------------
With the SPL plot attached:
Attachments
Hi,
Circlomanen: Thanks, that is very useful information, especially the comparison to other subs of similar size. Just like GM said:"...the 'ripple' isn't as bad as predicted...".
Cordraconis: I hope you had some fun with the Jakulis paper. In your script you have a number of area values as e.g.: STh=0,206m2 is that how AkAbak denotes cm^2? I think normally 206cm^2 would be 0,0206m^2, right? Anyway, you'll get me into AkAbak yet, as soon as the oil price falls and we're getting back to a sane work schedule around here (Texas).
Circlomanen: Thanks, that is very useful information, especially the comparison to other subs of similar size. Just like GM said:"...the 'ripple' isn't as bad as predicted...".
Cordraconis: I hope you had some fun with the Jakulis paper. In your script you have a number of area values as e.g.: STh=0,206m2 is that how AkAbak denotes cm^2? I think normally 206cm^2 would be 0,0206m^2, right? Anyway, you'll get me into AkAbak yet, as soon as the oil price falls and we're getting back to a sane work schedule around here (Texas).
tb46 said:
DOH!
Thanks tb46!
After correcting this (me and mathematics don't mix
), the SPL plot looked even stranger, whith a huge and broad dip around 80Hz. After looking for 1meter resonances in the system, I finally stumbled upon the Reflector element that simulates corner loading. Changing the distances to 0,5meter finally gave me the SPL plot Hornresp produces!
Some quick observations from my simulations:
- the cross sectional area of the 80Hz resonator can be made smaller at no penalty, (unless you need the HF cutoff to be broader.) --> less cabinet volume!
- a front compression chamber and/or any compression rate <1 (but same throat and mouth of conical segment!) gives a little more on the very low end, but reduces the lower knee. Omitting this gives less cabinet volume.
- a back compression chamber gives more output at the Higher knee. Usefull to make a gentle rising slope for room gain.
- the exit of the back compresssion chamber can be made quite small without penalty for the LF response. A Unity/Synergy Horn also has these small holes. (More backpressure = more cone control? = higher freq output on front of driver)
- the efficiency rises as you put the mouth more into the corner. I wonder how far you can go with that.
Todo:
- make the script more user friendly by using constants for the volumes and cross sectional areas
- add an active highpass and lowpass filter to simulate these on the plate amplifier module and to adjust for the desired SPL response of the finished active TH sub
- make the corner loading/reflectors more realistic (more pushed-against-the-wall instead of floating-at-45°-near-corner) or investigate the corner loading and listening point.
Cordraconis - Slowly getting there!
- find a way to simulate room gain into the acoustic outputCordraconis said:
So far I put the active LP (150Hz) and HP (25Hz) filtering of the plate amp into the script so now I have an SPL plot of the full available bandwidth of the sub. The cutoff freq was a bit of curve fitting and trying out untill it was similar to the curve found here:
http://www.lautsprechershop.de/hifi/index_en.htm?/hifi/verst_en.htm
(Edit: it's the DT-50 module. Look into the detailed description.)
Based on that, I removed the resonator at the beginning. I tried to adjust it to reduce a peak around 160Hz, but if I lower the filtering freq I can filter it out enough and have less cabinet volume. Mind you I can also filter in the sofware of my 5.1 card (I added a second LP filter in the script), so the slope can be made steeper.
I sorted out the Reflection to make it simulate more accurately how it will behave from its intended position in a corner of the room. It is now 3dB lower as the 1/8th space prediction of Hornresp. Why is something to find out later, but I can live with that for the moment.
So all that is left to do is try to simulate the room gain here. This should affect the acoustical output and NOT the electrical input as to give accurate results for the Xmax of the driver.
Ideally I can give the room dimensions and position of the doors and windows so a program can calculate the room gain function. Does anyone know of a program capable of this? (I'll google directly after this.)
Alternatively I just put a gain function at the desired freq into the script, but I haven't found a way to do this for the acoustical output. Anyone knows how to do this?
TIA,
Cordraconis, having a day off at work ;-)
Re: Tang Band Comments
There was considerable more output in the very low 20's, with a rather narrow ripple around 30Hz. As expected there was a narrow dip in the cone movement at 35Hz, but it split the peak in 2 halves so I was left with 2 slightly smaller peaks of about the same amplitude.
The resonator however was 120liters large, effectively doubling the size of the system! I think it would be safe to say that resonators are not too usefull for lower freq. Maybe for the upper freq, but due to lesser cone movement there active filtering/EQ can be used without the penalty of the stored resonant energy in the system.
Are you sure this is the plot at xmax? Try the Tools>Maximum SPL ... dialogue in the roll down menu of Hornresp. My Monacor SPH-212 is also an 8" driver and for the moment it runs into xmax at 113dB at 35Hz.
On the bottom it refers somewhere to the Thiele whitepaper, which said just the same.
There are no free lunches in audio, merely some seasoning to suit your tastes.
@tb46: I put a 35Hz 1/4 WL resonator in my script at the exit of the back compression chamber to see if it would reduce the excursion peak and what it would do to the SPL plot.Patrick Bateman said:
There was considerable more output in the very low 20's, with a rather narrow ripple around 30Hz. As expected there was a narrow dip in the cone movement at 35Hz, but it split the peak in 2 halves so I was left with 2 slightly smaller peaks of about the same amplitude.
The resonator however was 120liters large, effectively doubling the size of the system! I think it would be safe to say that resonators are not too usefull for lower freq. Maybe for the upper freq, but due to lesser cone movement there active filtering/EQ can be used without the penalty of the stored resonant energy in the system.
Killjoy said:
Are you sure this is the plot at xmax? Try the Tools>Maximum SPL ... dialogue in the roll down menu of Hornresp. My Monacor SPH-212 is also an 8" driver and for the moment it runs into xmax at 113dB at 35Hz.
The article basically states that you can interchange smaller cabinets and amplifier power for the desired extention. Or larger cabinets but then you run into excurstion limits.Killjoy said:
On the bottom it refers somewhere to the Thiele whitepaper, which said just the same.
There are no free lunches in audio, merely some seasoning to suit your tastes.
resonance attenuation
Hi,
cordraconis: Thanks for keeping us informed as to your progress in AkAbak, this thread is turning into a mini AkAbak toutorial (I hope, because I need it). As to the volume of the resonators I have been pondering about: your original Monacor SPH212 tapped horn showed some strong resonances @: 86Hz/+11dB_117Hz/+10dB_165Hz/+10dB_225Hz/+8dB_277Hz/+7dB_350Hz/+10dB, etc..
If one where to apply simple tube resonators with one end close and an I.D. in the vicinity of 1.5" to 3" (PVC pipe) the volumes would be relatively small; e.g.assuming a 2" pipe I.D.: 86Hz/2liter_117Hz/1.4liter_165Hz/1.0liter_225Hz/0.7liter_350Hz/0.5liter. (Total volume: 5.6liter internal volume.)
Now, as these would have to be one end closed tubes with some polyfill internal stuffing they resonate @ f,and @ 3f, 5f and so on, i.e.: a 77Hz tube would affect the 86Hz and the 225Hz resonance, and the 117Hz tube will also resonate @ the 350Hz resonance point. Which would leave one with the 165hz resonance to attenuate (or what the 77Hz resonator did not get). In other words three resonators would clean up the upper response irregularities, and would establish a base condition where active filtering/EQ would have a chance to work. Stuffing would be used to broaden the resonance peaks of the tubes, the tube volume determines the attenuation, and the tube length the resonance point. AkAbak should be helpful to determine the effectiveness of such a resonance attenuation scheme. I see the big problem more in the testing and tuning, this is also where the practical experience of the actual builders comes in.
I agree with your contention that resonators tend to grow quite large at the lower frequencies, and that any system of stored resonant energy will introduce its own possible problems, but, these tuning resonators would be quite small in comparison to the total tapped horn resonant system, and they seem be an elegant solution to the upper frequency enclosure resonances and comb filtering. Otherwise, I agree in general with the KISS principle and Hoffmann's iron law, but, this is supposed to be fun, right (and I'm in no positon to be even thinking about building right now, that leaves we with pondering)?
For a tube resonance formula see: http://en.wikipedia.org/wiki/Acoustic_resonance
Hi,
cordraconis: Thanks for keeping us informed as to your progress in AkAbak, this thread is turning into a mini AkAbak toutorial (I hope, because I need it). As to the volume of the resonators I have been pondering about: your original Monacor SPH212 tapped horn showed some strong resonances @: 86Hz/+11dB_117Hz/+10dB_165Hz/+10dB_225Hz/+8dB_277Hz/+7dB_350Hz/+10dB, etc..
If one where to apply simple tube resonators with one end close and an I.D. in the vicinity of 1.5" to 3" (PVC pipe) the volumes would be relatively small; e.g.assuming a 2" pipe I.D.: 86Hz/2liter_117Hz/1.4liter_165Hz/1.0liter_225Hz/0.7liter_350Hz/0.5liter. (Total volume: 5.6liter internal volume.)
Now, as these would have to be one end closed tubes with some polyfill internal stuffing they resonate @ f,and @ 3f, 5f and so on, i.e.: a 77Hz tube would affect the 86Hz and the 225Hz resonance, and the 117Hz tube will also resonate @ the 350Hz resonance point. Which would leave one with the 165hz resonance to attenuate (or what the 77Hz resonator did not get). In other words three resonators would clean up the upper response irregularities, and would establish a base condition where active filtering/EQ would have a chance to work. Stuffing would be used to broaden the resonance peaks of the tubes, the tube volume determines the attenuation, and the tube length the resonance point. AkAbak should be helpful to determine the effectiveness of such a resonance attenuation scheme. I see the big problem more in the testing and tuning, this is also where the practical experience of the actual builders comes in.
I agree with your contention that resonators tend to grow quite large at the lower frequencies, and that any system of stored resonant energy will introduce its own possible problems, but, these tuning resonators would be quite small in comparison to the total tapped horn resonant system, and they seem be an elegant solution to the upper frequency enclosure resonances and comb filtering. Otherwise, I agree in general with the KISS principle and Hoffmann's iron law, but, this is supposed to be fun, right (and I'm in no positon to be even thinking about building right now, that leaves we with pondering)?
For a tube resonance formula see: http://en.wikipedia.org/wiki/Acoustic_resonance
I have read and looked over all 42 pages and still have a question.
I have attempted to come up with a TTL to fit in a small space. Say 23 inches wide by 24.5 inches tall and 19.5 inches deep. These being the internal dimensions.
I came up with a design that may work as such, but only came up with a line length of 7.14 feet with an SD of 86.25. Equaling a 1/4 wave of 39hz. This seems fairly good if I was using a 12" driver, but making this for a 15" driver.
I drew it up and will post what I think will work, if anyone can let me know if it will or not.
My questions tho are these.
With such a small SD for the throat length, will it be benificial to make this over a standard reflex/ported box ?
Will having the the line equaling 39hz be acceptable for playing in the lower frequencies. Say 30hz and below ?
After I get the picture up of my design I have a few other questions to add.
The driver I am planning on useing has these specs.
Sens of 87.8 at 1w/1m
QTS or .42
FS of 24hz
RE of 3.9 ohms
One way Xmax of .59 inches
RMS Power of 750 watts
VAS of 7.92 cubic feet
If needing any other specs, feel free to ask.
Thank you for the responses.
I have attempted to come up with a TTL to fit in a small space. Say 23 inches wide by 24.5 inches tall and 19.5 inches deep. These being the internal dimensions.
I came up with a design that may work as such, but only came up with a line length of 7.14 feet with an SD of 86.25. Equaling a 1/4 wave of 39hz. This seems fairly good if I was using a 12" driver, but making this for a 15" driver.
I drew it up and will post what I think will work, if anyone can let me know if it will or not.
My questions tho are these.
With such a small SD for the throat length, will it be benificial to make this over a standard reflex/ported box ?
Will having the the line equaling 39hz be acceptable for playing in the lower frequencies. Say 30hz and below ?
After I get the picture up of my design I have a few other questions to add.
The driver I am planning on useing has these specs.
Sens of 87.8 at 1w/1m
QTS or .42
FS of 24hz
RE of 3.9 ohms
One way Xmax of .59 inches
RMS Power of 750 watts
VAS of 7.92 cubic feet
If needing any other specs, feel free to ask.
Thank you for the responses.
HornBass said:
Greets!
First: make/model of driver for my records? Any other specs such as Qms, Qes, Sd, Le, BL? Note that the listed sensitivity is way off WRT the rest of the specs, ditto if you meant efficiency. Qes would have to be around 0.8, which doesn't compute with a 0.42 Qts........
I assume from your Qs that you haven't simmed it in Hornresp or other horn designer.
If I understand you this is a tapped pipe, i.e. zero taper with a cross sectional area (CSA) = 86.25"^2 and that its 1/4 WL path = 7.14 ft = 85.68" x 86.25"^2 = 7389.9"^3 gross Vb.
Anyway, the specs need sorting out before pursuing this further.
GM
I'll have to buy the driver and measure those specs for you, as the manutacture doesn't have them.
Only number I do have in that list is the SD, which is 191 sq inches.
I tried Hornresp a little, still very new to the program and all that is involved in it. Will take a bit of time to get use to that over the normal winisd I use often. LOL
Thank you for responding so fast.
BTW, the design I drew out is just a straight tl line with no flare to it. Will this be a problem with a taped box ? Also will a multiple of bends hender the outcome of these boxes ?
Thank you again
Only number I do have in that list is the SD, which is 191 sq inches.
I tried Hornresp a little, still very new to the program and all that is involved in it. Will take a bit of time to get use to that over the normal winisd I use often. LOL
Thank you for responding so fast.
BTW, the design I drew out is just a straight tl line with no flare to it. Will this be a problem with a taped box ? Also will a multiple of bends hender the outcome of these boxes ?
Thank you again
You're welcome!
If it's a 15", Sd is no where near 191"^2, this would be its entire surface area including its metal frame and then only if its diameter is ~15.6".............
If this was published by the manufacturer you might want to consider buying a different brand as you're likely going to be disappointed with this one's performance/build quality.
Yeah, I find it anything but intuitive, but the price is right and I'm not willing to take the time right now to unravel Akabak's Byzantine construct just to sim simple tapped pipe/horns and for sure not going to spend what little cognizant quality time I have left indulging in learning enough computer programming to design my own software.
No, AFAIK tapped TLs were invented by Jensen ~56 yrs ago, though it was a flop for reasons I can only speculate, such as the serious delay problem and inability to inexpensively make a low insertion loss passive XO, forcing them to be severely BW limited to a very low acoustic XO, but IMO they are the best bang/buck/size/construction ease for a typical HIFI app now that relatively cheap digital EQ/TD is available.
No, multiple bends will actually help damp down some of its out of passband resonances.
GM
If it's a 15", Sd is no where near 191"^2, this would be its entire surface area including its metal frame and then only if its diameter is ~15.6".............
If this was published by the manufacturer you might want to consider buying a different brand as you're likely going to be disappointed with this one's performance/build quality.
Yeah, I find it anything but intuitive, but the price is right and I'm not willing to take the time right now to unravel Akabak's Byzantine construct just to sim simple tapped pipe/horns and for sure not going to spend what little cognizant quality time I have left indulging in learning enough computer programming to design my own software.
No, AFAIK tapped TLs were invented by Jensen ~56 yrs ago, though it was a flop for reasons I can only speculate, such as the serious delay problem and inability to inexpensively make a low insertion loss passive XO, forcing them to be severely BW limited to a very low acoustic XO, but IMO they are the best bang/buck/size/construction ease for a typical HIFI app now that relatively cheap digital EQ/TD is available.
No, multiple bends will actually help damp down some of its out of passband resonances.
GM
Chris8sirhC said:
Hello Chris8sirhC, sorry I took so long to respond. The 15.00 W2 is not a subwoofer. The driver specs are available on the www.assistanceaudio.com website under the Ciare manufactorer tab. It has a very high Qms = 25+. That's why I modelled it in Hornresp. It seems to me that if you keep the Qms high (above 6-8) and the Qes = .4-.6 (as mentioned elsewhere in this thread) you get an easy to mod driver as a TH.