I've seen at least 5 Onken bass enclosures
1) The smallest: La Mini-Onken. A 80 liters BR using a Focal 10C01.
2) La petite Onken: A 140 liters BR using an Altec 414
3) L'enceinte Onken: A 288 liters Br using a 416-8A as described in the previous links.
4) L'Onken W: a 360 liters using TWO 416-8A
5) L'Onken pavillon: This one is a front loaded horn that uses TWO 515B. This can be considered as a modified JBL4550.
Please, have a look at the http://www.artec-france.com site. Mr Voiturier runs the Artec company but also provides free plans. This represents the results of his researchs. I personnaly built my bass speakers using these information.
Kind Regards,
J.P.
1) The smallest: La Mini-Onken. A 80 liters BR using a Focal 10C01.
2) La petite Onken: A 140 liters BR using an Altec 414
3) L'enceinte Onken: A 288 liters Br using a 416-8A as described in the previous links.
4) L'Onken W: a 360 liters using TWO 416-8A
5) L'Onken pavillon: This one is a front loaded horn that uses TWO 515B. This can be considered as a modified JBL4550.
Please, have a look at the http://www.artec-france.com site. Mr Voiturier runs the Artec company but also provides free plans. This represents the results of his researchs. I personnaly built my bass speakers using these information.
Kind Regards,
J.P.
I was working on my cross-overs (N2400) today and verified which version of the JBL D130 I have.
They are the early 16 ohm version, dcr is about 15 ohms, and according to JBL FS is 37Hz, efficiency rated at 102.8dB/W/M. These are really not exactly the same drivers listed in the current JBL driver database although there may be some similarities beyond the model designation and size.
The specific description of this driver is the signature series D130 Full Range driver. It has the aluminum dustcap, 16 ohm impedance, aluminum edge wound voice coil (not copper) and is rated optimistically for 30 - 17kHz operation. Power rating is 25 watts, not the 75 cited for the later version. Does anyone have T-S parameters for this driver, not the later version?
They are the early 16 ohm version, dcr is about 15 ohms, and according to JBL FS is 37Hz, efficiency rated at 102.8dB/W/M. These are really not exactly the same drivers listed in the current JBL driver database although there may be some similarities beyond the model designation and size.
The specific description of this driver is the signature series D130 Full Range driver. It has the aluminum dustcap, 16 ohm impedance, aluminum edge wound voice coil (not copper) and is rated optimistically for 30 - 17kHz operation. Power rating is 25 watts, not the 75 cited for the later version. Does anyone have T-S parameters for this driver, not the later version?
Greets!
The only older D130 measured specs I have are some '73 woofers:
Fs = 37.5 Hz
Re = 6.24 ohms
Vas = 19.222126 ft^3 (544.31 L)
Sd = 130.698"^2 (843.212 cm^2)
Le = 0.72 mH
Qts = 0.197
Xmax = ~0.8 mm
Anyway, in the good ol' days we normally built cabs that were big enough to be tuned to around 40Hz and used electronic damping to 'fill up' the cab as required to get a ~full sounding bass, so if it were me, I'd add enough series R to get it down to around 38-40 Hz at the desired 'n' factor and hopefully it won't be too big.
GM
The only older D130 measured specs I have are some '73 woofers:
Fs = 37.5 Hz
Re = 6.24 ohms
Vas = 19.222126 ft^3 (544.31 L)
Sd = 130.698"^2 (843.212 cm^2)
Le = 0.72 mH
Qts = 0.197
Xmax = ~0.8 mm
Anyway, in the good ol' days we normally built cabs that were big enough to be tuned to around 40Hz and used electronic damping to 'fill up' the cab as required to get a ~full sounding bass, so if it were me, I'd add enough series R to get it down to around 38-40 Hz at the desired 'n' factor and hopefully it won't be too big.
GM
Hi GM,
Thanks for all the tips and useful information. I have noticed how series R seems to have a big effect on low frequency extension obviously at some loss in efficiency.
Most of the variations I have attempted are based on revising only Re, Fs, and Sd, (known to be different) otherwise I have stuck pretty much with the parameters JBL lists for the later 8 ohm version. I get a calculated Qts of 0.253 which agrees closely with the published spec, however it is not close to what you measured.
I am assuming (perhaps naively hoping) that despite the difference in impedance the electrical Q of the voice coil should not be that different, slightly more than twice the Re of the 8 ohm driver based on crude measurements, and I would expect inductance to about twice, so in theory Qes should be about the same? (This parameter along with Qts has a pretty big influence on the box tuning.)
I am just wondering whether I am deluding myself into thinking these are going to work well, and I need to face reality and buy some A416??
Based on the calculator program and what limited information I have for these drivers they should (might) work quite well, but others have expressed concerns about limited xmax, presumably if this were going to be a problem for me I would have had this issue already with the C37 reflex cabs I currently use? One of the attractions is that the large cone area negates the need for large excursions at the volume levels I habitually listen at, and hence I subjectively get cleaner bass, and they seem to get a lot further down than that 37Hz Fs would seem to imply.
Also these will never see the far side of 100dBspl in regular use, I don't have the amplifier power usually. (Although I do have a pair of 30W PP 300B monoblocks sitting in my closet and they have a very high source impedance on the 16 ohm tap > 8 ohms.)
Thanks for your encouragement and assistance - it is appreciated.
Thanks for all the tips and useful information. I have noticed how series R seems to have a big effect on low frequency extension obviously at some loss in efficiency.
Most of the variations I have attempted are based on revising only Re, Fs, and Sd, (known to be different) otherwise I have stuck pretty much with the parameters JBL lists for the later 8 ohm version. I get a calculated Qts of 0.253 which agrees closely with the published spec, however it is not close to what you measured.
I am assuming (perhaps naively hoping) that despite the difference in impedance the electrical Q of the voice coil should not be that different, slightly more than twice the Re of the 8 ohm driver based on crude measurements, and I would expect inductance to about twice, so in theory Qes should be about the same? (This parameter along with Qts has a pretty big influence on the box tuning.)
I am just wondering whether I am deluding myself into thinking these are going to work well, and I need to face reality and buy some A416??
Based on the calculator program and what limited information I have for these drivers they should (might) work quite well, but others have expressed concerns about limited xmax, presumably if this were going to be a problem for me I would have had this issue already with the C37 reflex cabs I currently use? One of the attractions is that the large cone area negates the need for large excursions at the volume levels I habitually listen at, and hence I subjectively get cleaner bass, and they seem to get a lot further down than that 37Hz Fs would seem to imply.
Also these will never see the far side of 100dBspl in regular use, I don't have the amplifier power usually. (Although I do have a pair of 30W PP 300B monoblocks sitting in my closet and they have a very high source impedance on the 16 ohm tap > 8 ohms.)
Thanks for your encouragement and assistance - it is appreciated.
other Onken sources
If you look up the Joe Net archives http://mailman.io.com/pipermail/sound/ (which alas can’t be searched, though I recall there was a flurry on Onkens in October last year; or search Audio Asylum http://db.audioasylum.com/ there’s quite a bit on Onkens.
If you look up the Joe Net archives http://mailman.io.com/pipermail/sound/ (which alas can’t be searched, though I recall there was a flurry on Onkens in October last year; or search Audio Asylum http://db.audioasylum.com/ there’s quite a bit on Onkens.
Greets!
FWIW, here's another Onken thread I responded to: http://www.audioroundtable.com/HighEfficiencySpeakers/messages/2466.html
GM
FWIW, here's another Onken thread I responded to: http://www.audioroundtable.com/HighEfficiencySpeakers/messages/2466.html
GM
You're welcome!
Correct, all you're doing is trading efficiency for a flatter BW (lowering its DF).
When you change just those values, it changes BL, Mms, Cms, so if the program you're using requires any of these to be inputted, then the calc'd design can be pretty far off:
Cms = Vas/(Sd^2*rho*c^2)
where:
Vas is in m^3 (liters*0.001)
Sd is in cm^2
c is in meters/sec*0.0001 to get Cms in mm/N
then:
Mms = 1/[(2*pi*Fs)^2*Cms]
BL = [(2*Pi*Fs*Re*Mms)/Qes]^0.5
Since Qes = (2*Pi*Fs*Mms*Re)/BL^2 your ~naive assumption is correct.
Any point source driver is inherently capable of working just fine down to ~0.707*Fs in a typical sealed, BR, etc., alignment with the caveat of will it play loud enough at low distortion for the app once the room's effect (if any) is factored in, so the D130 is quite capable of being used in a ~26-28 Hz alignment, though historically (pre T/S) they would have been tuned around 1.4142*Fs to ensure decent efficiency/dynamic headroom (protect it against consumers) and the fact that there were precious few sources with any output of note below 45-50 Hz. Today of course, we have music with content down to 16 Hz, so a much wider BW signal chain is required if reproducing these are required, and in the case of movie and other special effects, it will need to be solid down to <8-9 Hz, so not for the impecunious or faint of heart.
WRT the D130, let's assume you build the 416 Onken and 'fill it up' electronically till its ~half space flat (up against a wall position). It will be Xmax limited to ~3 W/107 dB/m/stereo peaks in the ~50-70 Hz BW before any room/boundary gain is factored in. Ignoring organ/special effects/room gain, this equates to a minimum of 83 dB/m and as much as 92 dB/m average depending on the source material, so for most folks this is more than enough SPL. If not, then a more efficient cab alignment is best and fill in the bottom end with a complementary sub system.
That said, our hearing acuity rolls off with decreasing frequency and any driver with an accordian surround has a rising rate suspension that allows it to be overdriven up to a point without its distortion being objectionable to most folks, kind of like the euphonic distortion of a typical tube amp.
For instance, my Altec 515Bs can be safely driven to at least 2x Xmax, which increases its effective power handling by a factor of four. Assuming the D130 is typical (and it is IIRC), then this increases the above SPLs ~6 dB if the amp's willing.
Anyway, if it were me I would stick them in ~15 ft^3 net cabs tuned to ~35 Hz, and since it will be tube driven, use a signal level network to convert it to a current source and reduce DF till it's ~flat in-room. If you happen to have an old theater or similar design amp with a ~4-20 ohms bass control, then you're set.
GM
Correct, all you're doing is trading efficiency for a flatter BW (lowering its DF).
When you change just those values, it changes BL, Mms, Cms, so if the program you're using requires any of these to be inputted, then the calc'd design can be pretty far off:
Cms = Vas/(Sd^2*rho*c^2)
where:
Vas is in m^3 (liters*0.001)
Sd is in cm^2
c is in meters/sec*0.0001 to get Cms in mm/N
then:
Mms = 1/[(2*pi*Fs)^2*Cms]
BL = [(2*Pi*Fs*Re*Mms)/Qes]^0.5
Since Qes = (2*Pi*Fs*Mms*Re)/BL^2 your ~naive assumption is correct.
Any point source driver is inherently capable of working just fine down to ~0.707*Fs in a typical sealed, BR, etc., alignment with the caveat of will it play loud enough at low distortion for the app once the room's effect (if any) is factored in, so the D130 is quite capable of being used in a ~26-28 Hz alignment, though historically (pre T/S) they would have been tuned around 1.4142*Fs to ensure decent efficiency/dynamic headroom (protect it against consumers) and the fact that there were precious few sources with any output of note below 45-50 Hz. Today of course, we have music with content down to 16 Hz, so a much wider BW signal chain is required if reproducing these are required, and in the case of movie and other special effects, it will need to be solid down to <8-9 Hz, so not for the impecunious or faint of heart.
WRT the D130, let's assume you build the 416 Onken and 'fill it up' electronically till its ~half space flat (up against a wall position). It will be Xmax limited to ~3 W/107 dB/m/stereo peaks in the ~50-70 Hz BW before any room/boundary gain is factored in. Ignoring organ/special effects/room gain, this equates to a minimum of 83 dB/m and as much as 92 dB/m average depending on the source material, so for most folks this is more than enough SPL. If not, then a more efficient cab alignment is best and fill in the bottom end with a complementary sub system.
That said, our hearing acuity rolls off with decreasing frequency and any driver with an accordian surround has a rising rate suspension that allows it to be overdriven up to a point without its distortion being objectionable to most folks, kind of like the euphonic distortion of a typical tube amp.
For instance, my Altec 515Bs can be safely driven to at least 2x Xmax, which increases its effective power handling by a factor of four. Assuming the D130 is typical (and it is IIRC), then this increases the above SPLs ~6 dB if the amp's willing.
Anyway, if it were me I would stick them in ~15 ft^3 net cabs tuned to ~35 Hz, and since it will be tube driven, use a signal level network to convert it to a current source and reduce DF till it's ~flat in-room. If you happen to have an old theater or similar design amp with a ~4-20 ohms bass control, then you're set.
GM
Hi GM,
Thanks for the confirmations and the additional information.. The simulations I am running are starting to come into line with what I would expect to see if the Onken enclosure is going to work with these drivers.
There is definitely a process to be followed to get the best overall compromise between extension, flatness and efficiency. Given that they are so efficient to start with and taking into account the halfspace/ room boundary effects I think it is feasible to get what I want.
The vent geometry I am contemplating is just inside the Onken ratio of .85 - 1 of S vent to Sd, anything larger (than 0.9) seems to cause problems both with box tuning and effective length of the ports.
One viable tuning looks like about -3dB around 42Hz which keeps things reasonable in size, and maintains about 97dB efficiency before room effects are accounted for.
Box volume is 9cu ft total for this configuration, amplifier and x -over is 4 ohms which imho might be a tad low for my se amplifiers + inductors. I can always make the DF/efficiency trade off and go for a lower tuning larger box combo.
Linear Xmax is only 0.8mm, but I bet the actual xmax is a lot greater than this. I have measured usable output at 25Hz with the stock box driven by my pp 300B amplifier, and I am sure the excursion at 25Hz has got to be much greater than this at meaningful spls..
I am staying right around the onken tuning of 6.34 - I believe this is nothing more than the system q multiplied by 10, I have got that right or am I all wet...
Tuning to a lower cut off is appealing as long as I don't too carried away, plus I suspect there are other JBL woofers that will sub with minor retuning later if I want more efficiency & spls..
Again thanks for the sanity check..
Thanks for the confirmations and the additional information.. The simulations I am running are starting to come into line with what I would expect to see if the Onken enclosure is going to work with these drivers.
There is definitely a process to be followed to get the best overall compromise between extension, flatness and efficiency. Given that they are so efficient to start with and taking into account the halfspace/ room boundary effects I think it is feasible to get what I want.
The vent geometry I am contemplating is just inside the Onken ratio of .85 - 1 of S vent to Sd, anything larger (than 0.9) seems to cause problems both with box tuning and effective length of the ports.
One viable tuning looks like about -3dB around 42Hz which keeps things reasonable in size, and maintains about 97dB efficiency before room effects are accounted for.
Box volume is 9cu ft total for this configuration, amplifier and x -over is 4 ohms which imho might be a tad low for my se amplifiers + inductors. I can always make the DF/efficiency trade off and go for a lower tuning larger box combo.
Linear Xmax is only 0.8mm, but I bet the actual xmax is a lot greater than this. I have measured usable output at 25Hz with the stock box driven by my pp 300B amplifier, and I am sure the excursion at 25Hz has got to be much greater than this at meaningful spls..
I am staying right around the onken tuning of 6.34 - I believe this is nothing more than the system q multiplied by 10, I have got that right or am I all wet...
Tuning to a lower cut off is appealing as long as I don't too carried away, plus I suspect there are other JBL woofers that will sub with minor retuning later if I want more efficiency & spls..
Again thanks for the sanity check..
Greets!
You're welcome!
Yes, and why I recommended a large enough cab tuned low enough to allow for a wide range of alignments/driver choices.
Hmm, 9 ft^3 tuned to ~41 Hz only requires 12" long vents with SV = 1, considerably shorter than the Grande Onken.
I'm not sure how the 'n' value is derived, but n = 6.34 is a 4th order Butterworth and n = 5.7 is a T/S max flat 0.7 alignment, so I'm thinking you're 'all wet'.
Anyway, when I load the D130 specs I posted into my calculator, I get a net Vb = 11.993 ft^3 using n = 6.34 and 4 ohms series R, so I'm curious how you arrived at 9 ft^3 total, which I assume includes the vents also.
GM
You're welcome!
Yes, and why I recommended a large enough cab tuned low enough to allow for a wide range of alignments/driver choices.
Hmm, 9 ft^3 tuned to ~41 Hz only requires 12" long vents with SV = 1, considerably shorter than the Grande Onken.
I'm not sure how the 'n' value is derived, but n = 6.34 is a 4th order Butterworth and n = 5.7 is a T/S max flat 0.7 alignment, so I'm thinking you're 'all wet'.
Anyway, when I load the D130 specs I posted into my calculator, I get a net Vb = 11.993 ft^3 using n = 6.34 and 4 ohms series R, so I'm curious how you arrived at 9 ft^3 total, which I assume includes the vents also.
GM
Hi GM,
I actually ended up going to slightly over 10 cu ft for the current pass..
Tuning is just below 40Hz. I haven't a lot of amplifier power so I need to maintain reasonable efficiency.. LOL
Umm, I'm taking a bath right now.. LOL So the N number describes the box alignment. (I think that was sort of what I was thinking of. ) I did ultimately stick with the 6.34 alignment. The 5.7 T/S flat alignment would be attractive but results in a very deep box or alternately a much higher tuning.
The calculator indicates that port lengths in excess of 35cm corrected length are not advisable. (Basically it states that ports lengths longer than this indicate the driver is not suitable for the enclosure.)
Rg is currently 7 ohms with about 3.5 of that coming from the amplifier and the rest from a resistor and the inductor dcr...
The measured Re of my drivers is a little over 14 ohms.
Will keep you posted. Thanks!
I actually ended up going to slightly over 10 cu ft for the current pass..
Tuning is just below 40Hz. I haven't a lot of amplifier power so I need to maintain reasonable efficiency.. LOL
Umm, I'm taking a bath right now.. LOL So the N number describes the box alignment. (I think that was sort of what I was thinking of.
) I did ultimately stick with the 6.34 alignment. The 5.7 T/S flat alignment would be attractive but results in a very deep box or alternately a much higher tuning. The calculator indicates that port lengths in excess of 35cm corrected length are not advisable. (Basically it states that ports lengths longer than this indicate the driver is not suitable for the enclosure.)
Rg is currently 7 ohms with about 3.5 of that coming from the amplifier and the rest from a resistor and the inductor dcr...
The measured Re of my drivers is a little over 14 ohms.
Will keep you posted. Thanks!
I am no expert on the subject of speaker design in general or in regards to the Onken which I am currently having built. I used the cited calculator to do my design with some revisions to translate from metric lengths and volumes to US measures. Lots of people I understand have used this calculator successfully for designing Onken speaker systems.
There seem to be certain constraints applied in order to follow the Onken methodology, which is closely based on the Jensen Ultraflex.
For example the Onken port area should be no less than 85% of the driver surface area, and no more than 100%, the port size has a very direct bearing on the box volume in this design as does the source impedance of the amplifier, and hence the low frequency cutoff.
Alignment can be the Onken 4th order butterworth (N=6.34) or maximally flat (N=5.7) I choose the Onken alignment because the port length is influenced by the tuning chosen, and the 35cm port length limit listed which I elected to respect. I have subsequently heard of Onken variants with longer ports than this.
GM was very helpful to me in resolving a bunch of issues and I designed my boxes based largely on his recommendations, hopefully he will be able to explain this further in a way that I cannot.
I will post more information and impressions once I receive the new cabinets, install the drivers and do some preliminary tweaking.
Interestingly enough my enclosures are only slightly different in size and volume to the originals shown in the manual.
There seem to be certain constraints applied in order to follow the Onken methodology, which is closely based on the Jensen Ultraflex.
For example the Onken port area should be no less than 85% of the driver surface area, and no more than 100%, the port size has a very direct bearing on the box volume in this design as does the source impedance of the amplifier, and hence the low frequency cutoff.
Alignment can be the Onken 4th order butterworth (N=6.34) or maximally flat (N=5.7) I choose the Onken alignment because the port length is influenced by the tuning chosen, and the 35cm port length limit listed which I elected to respect. I have subsequently heard of Onken variants with longer ports than this.
GM was very helpful to me in resolving a bunch of issues and I designed my boxes based largely on his recommendations, hopefully he will be able to explain this further in a way that I cannot.
I will post more information and impressions once I receive the new cabinets, install the drivers and do some preliminary tweaking.
Interestingly enough my enclosures are only slightly different in size and volume to the originals shown in the manual.
Greets!
Different alignment philosopy. N = 5, RG = 0 is the closest to a typical box calculator's T/S max flat. Larger, longer vents can cause excessive comb filtering with the driver's output above Fb and why you often see damping material in folk's Onkens even when the vents are <35 cm long and the minimum recommended area.
GM
Different alignment philosopy. N = 5, RG = 0 is the closest to a typical box calculator's T/S max flat. Larger, longer vents can cause excessive comb filtering with the driver's output above Fb and why you often see damping material in folk's Onkens even when the vents are <35 cm long and the minimum recommended area.
GM
What do I do with L'? Do I use it together with the vent volume to recalculate the vent width?
I get the given width. But what is L then?
No matter, I am happy that everything fits. Ciare HX201 in a 30*30*100cm floorstand speaker (omnidirectional), 33cm port lengt at onken alignment with 85% Sd.
I get the given width. But what is L then?
No matter, I am happy that everything fits. Ciare HX201 in a 30*30*100cm floorstand speaker (omnidirectional), 33cm port lengt at onken alignment with 85% Sd.
Greets!
L vent is the acoustic length required to tune the cab to Fb. L' vent is how long it should be to achieve it, so when you design the cab its depth must either be at least whatever L' vent is + whatever its width for minimum depth or L vent + the difference between L vent and L' vent + a near boundary factor of the effective radius of the vent.
GM
L vent is the acoustic length required to tune the cab to Fb. L' vent is how long it should be to achieve it, so when you design the cab its depth must either be at least whatever L' vent is + whatever its width for minimum depth or L vent + the difference between L vent and L' vent + a near boundary factor of the effective radius of the vent.
GM
Hi GM,
I have been reconsidering the D130 as a driver in my Onken cabinet, and determined that the Eminence Delta Pro 15A T-S parameters line up as well or even better than the D130 with the box parameters I have chosen. (The boxes are being built as we speak.) It has a higher xmax and much higher power handling and everything else lines up pretty nicely. Efficiency will be comparable. Box tuning is slightly more favorable than the D130, changed from 6.34 to 6.24.. I can post the ts parameters later if this is helpful.
Cone mass is close to that of the D130, so I assume transient response should be ok even into the low mids(?). Sd is a little larger which means vent area is 84.4 % of Sd, but I think this ought to be ok. (I was a little over 85 % with the D130.)
In this scenario I might use a mid horn of some description and one of the following tweeters: JBL 2402, JBL 075. No idea what to do about mids right now. (Edgar horn??)
Alternate scenarios include a radia ribbon from bohlender-graebner (sic) or possibly a JBL 175, both of these can be crossed over low enough to allow for a 2 way system at least initially.
I am thinking either ussound or partsexpress as suppliers.
Any thoughts on why I ought not to go this route? I figure driver distortion is not going to be an issue at the SPL levels I listen at or can achieve with the available power. I plan to push the woofer with a 30Wrms pp triode amplifier max.
System will be bi or tri-amped depending on drivers used.. I have LOTS of amplifiers..
Thanks for your thoughts.
I have been reconsidering the D130 as a driver in my Onken cabinet, and determined that the Eminence Delta Pro 15A T-S parameters line up as well or even better than the D130 with the box parameters I have chosen. (The boxes are being built as we speak.) It has a higher xmax and much higher power handling and everything else lines up pretty nicely. Efficiency will be comparable. Box tuning is slightly more favorable than the D130, changed from 6.34 to 6.24.. I can post the ts parameters later if this is helpful.
Cone mass is close to that of the D130, so I assume transient response should be ok even into the low mids(?). Sd is a little larger which means vent area is 84.4 % of Sd, but I think this ought to be ok. (I was a little over 85 % with the D130.)
In this scenario I might use a mid horn of some description and one of the following tweeters: JBL 2402, JBL 075. No idea what to do about mids right now. (Edgar horn??)
Alternate scenarios include a radia ribbon from bohlender-graebner (sic) or possibly a JBL 175, both of these can be crossed over low enough to allow for a 2 way system at least initially.
I am thinking either ussound or partsexpress as suppliers.
Any thoughts on why I ought not to go this route? I figure driver distortion is not going to be an issue at the SPL levels I listen at or can achieve with the available power. I plan to push the woofer with a 30Wrms pp triode amplifier max.
System will be bi or tri-amped depending on drivers used.. I have LOTS of amplifiers..
Thanks for your thoughts.
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