Theoretically drivers with a lack of cone area, or a lack of excursion capability can benefit from the DCR design due to the improved cone loading and excursion control, making these same drivers a little more competitive ....
I attached some pics and data for DCRs so you can get a better idea of what we are talking about ...
I attached some pics and data for DCRs so you can get a better idea of what we are talking about ...
Attachments
Hi Matthew Morgan,
Post #795: "... I think .7 no longer has the "ABC" feature as they call it , but if i am wrong about that then i should update!"
In using WinISD 0.7.0.900, and it has the ABC(DCR) alignment feature, and seems to work fine. The biggest problem I found is the driver entry into WinISD in general, I'll attach some notes I copied out of a thread started by Zero D.
Another one to google is "DCR Claudio Negro", I see you already have some pictures from there in Post #801; I like that DCTT2 fold you are showing there, but you better make sure that the T/S parameters are correct, that does not look easily tuneable.
Regards,
Post #795: "... I think .7 no longer has the "ABC" feature as they call it , but if i am wrong about that then i should update!"
In using WinISD 0.7.0.900, and it has the ABC(DCR) alignment feature, and seems to work fine. The biggest problem I found is the driver entry into WinISD in general, I'll attach some notes I copied out of a thread started by Zero D.
Another one to google is "DCR Claudio Negro", I see you already have some pictures from there in Post #801; I like that DCTT2 fold you are showing there, but you better make sure that the T/S parameters are correct, that does not look easily tuneable.
Regards,
Attachments
ROUGH OFFSET-ML-TRANSFLEX FOR THE LAB12, 35HZ TUNE
To give you even more to chew on
, for giggles and the sake of science i worked out a rough plan for an OFFSET-MASS-LOADED-TRANSFLEX based around your (or Luuker's) Lab12 , or any Lab12 for that matter ...
The offset and stuffing really help to tame the 3rd harmonic peak/notch allowing much more bandwidth ... The offset also allows the box to be made smaller .... This worked out to about 60 liters ... 35hz is only 3db down according to the equivalent simulation, and the reason i say "equivalent" is because Hornresponse will not allow us to simulate an ML-transflex with this kind of offset (since we are relying upon the throat chamber which has no offset) , however a tapered (imagine reverse expansion) transflex CAN be offset and is also equivalent to what we want to build because bass waves are so damn long that they do not care if the changes in expansion or taper are smooth or stepped, it simply looks all the same to the bass wave ........ Mr Volvotreter used this stepped method in a tapped horn many years ago and other folks have also used this method with success since then ...
Hopefully nobody minds that i am having fun with my pulp art fonts in these attachments
hehehehe
The sketch is rough and subject to revision, if someone wants to actually build this thing i will flesh it out and give it more detail ..
To give you even more to chew on
, for giggles and the sake of science i worked out a rough plan for an OFFSET-MASS-LOADED-TRANSFLEX based around your (or Luuker's) Lab12 , or any Lab12 for that matter ...The offset and stuffing really help to tame the 3rd harmonic peak/notch allowing much more bandwidth ... The offset also allows the box to be made smaller .... This worked out to about 60 liters ... 35hz is only 3db down according to the equivalent simulation, and the reason i say "equivalent" is because Hornresponse will not allow us to simulate an ML-transflex with this kind of offset (since we are relying upon the throat chamber which has no offset) , however a tapered (imagine reverse expansion) transflex CAN be offset and is also equivalent to what we want to build because bass waves are so damn long that they do not care if the changes in expansion or taper are smooth or stepped, it simply looks all the same to the bass wave ........ Mr Volvotreter used this stepped method in a tapped horn many years ago and other folks have also used this method with success since then ...
Hopefully nobody minds that i am having fun with my pulp art fonts in these attachments
heheheheThe sketch is rough and subject to revision, if someone wants to actually build this thing i will flesh it out and give it more detail ..
Attachments
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This is great! Ok , i will update now , and yeah, the driver entry was buggy in my earlier version too ....
Yessir , i have read through all of Claudio's stuff trying to learn more about DCRs .... The DCTT2 was just one of the other examples i found out on the interwebz , some of those examples intrigue me because they have longer stretched out aspect ratios that are almost reminiscent of ML-TLs ...... It gives me an idea for a DCR-TL ... 🙂
A basic DCR script in Akabak is quite simple, literally could be done in 11 lines of script. Don Hills has a nice How-To for Akabak and it ends with a DCR example:
http://www.diyaudio.com/forums/multi-way/90362-akabak-simulator-2.html#post1840182
Here is the script from Don Hill's example in condensed 11 line format. Note that Akabak is smart and can use English or metric units, for example you can change the lengths and diameters of the ducts from 10cm to 2in - pretty convenient.
The basis of the design starts using a standard bass reflex program to estimate the volume and duct size for a typical tuning you desire. Take that system volume and use 2/3rds for upper chamber where driver is, 1/3rd for lower chamber, take duct prediction and put it in each chamber and same duct connecting two chambers. Use this as the baseline to tweak and refine the performance with a full blown DCR simulation. Reducing the length of the interchamber duct can smooth response at the expense of extension and level of bass. Reducing overall volume will increase SPL and reduce bass extension. Similarly, reducing duct length or increasing duct dia reduces bass extension but increases SPL.
Code:
System 'DCR' | Specs for system prescribed: vt=77L, f2=34.04Hz, v1=51.3L, v2=25.7L, f1=30.2Hz
Def_Driver 'AD8066W8' Meas_Dipole dD=16.5cm fs=39Hz Vas=49L Qms=4.2 Qes=0.52 Re=7.6ohm ExpoLe=0.618 | Define driver T/S params
Driver 'Driver' Def='AD8066W8' Node=1=0=2=3 | Define driver connections node 1=amp, node 0=ground, node 2=frontside of cone, node 3=back side of cone
Radiator 'Rad_Driver' Def='Driver' Node=2 | Radiator for driver face
Enclosure 'V1' Node=3 Vb=51.3L Qb/fo=0.5 Lb=10cm | Upper chamber
Duct 'P1' Node=3=4 dD=10cm Len=40.3cm QD/fo=2 | Vent for top chamber
Radiator 'Rad_P1' Def='P1' Node=4 | Radiator for upper vent
Duct 'P2' Node=3=5 dD=10cm Len=40.3cm QD/fo=2 | Duct connecting two chambers
Enclosure 'V2' Node=5 Vb=25.7L Qb/fo=0.5 Lb=10cm | Lower chamber
Duct 'P3' Node=5=6 dD=10cm Len=40.3cm QD/fo=2 | Vent for lower chamber
Radiator 'Rad_P3' Def='P3' Node=6 | Radiator for lower ventI have built several DCR's using full range drivers and they sound quite nice - very rich deep bass that is smooth and non-boomy. Using the Akabak script, the as-built DCR's measure close to predictions.
http://www.diyaudio.com/forums/full-range/252627-viva-la-vifa-curvy-cabinet-dcr-tc9fd.html
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They look like this, but replace the duct going to the outside with an 8 in hole in 3/4in ply facing the driver:
Xrk,
This is really good to know, and your Viva-Vifa cabinet is very crafty and cool ! 🙂
I have always wondered a few things about DCRs , such as how they might perform in TL form , or tapped , or with a small chamber in front of the driver , these are some of the reasons for me to learn Akabak
..
To give you even more to chew on
The offset and stuffing really help to tame the 3rd harmonic peak/notch allowing much more bandwidth ... The offset also allows the box to be made smaller .... This worked out to about 60 liters ... 35hz is only 3db down according to the equivalent simulation, and the reason i say "equivalent" is because Hornresponse will not allow us to simulate an ML-transflex with this kind of offset (since we are relying upon the throat chamber which has no offset) , however a tapered (imagine reverse expansion) transflex CAN be offset and is also equivalent to what we want to build because bass waves are so damn long that they do not care if the changes in expansion or taper are smooth or stepped, it simply looks all the same to the bass wave ........ Mr Volvotreter used this stepped method in a tapped horn many years ago and other folks have also used this method with success since then ...
Hopefully nobody minds that i am having fun with my pulp art fonts in these attachments
The sketch is rough and subject to revision, if someone wants to actually build this thing i will flesh it out and give it more detail ..
Mr. MMJ, I think you might have just given me a design =) that's a full 20 liters smaller than my reflex box AND outperforms it by a few dB. I'm guessing that's 1/2" ply? If not it will be a very tight squeeze with 13.5" outside panels and a 12" driver!
Placing the motor in the airflow path seems like it might give enough cooling to safely run the LAB12 at RMS voltage. I've read that for sine wave based music you should limit to less than "RMS" if the Pe was tested with pink noise.
XRK I haven't forgotten about you! I will sketch up that design soon and compare the finished outside volume, also a cool looking design!
Sent from my iPhone using Tapatalk
Palsa ,
That is correct! 1/2 inch ply 🙂
and yes , the motor on the Lab12 should run nice and cool this way , hopefully the "mechanical noise" on the lab12 wont be an issue ......
Luuker , i worked on it a bit last night , your 12TBX100 is an extremely capable driver and can be used in a very small cabinet ......
A prudent solution would be a 40hz tapped horn or maybe a rear loaded horn, but i will continue to look into other alignments as well ...
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Matthew.
12tbx100 speaker is brutal and I am glad that you can help me. I tried many times simulation with this speaker and I failed. I mainly go for the small size and 40Hz tuning 🙂
12tbx100 speaker is brutal and I am glad that you can help me. I tried many times simulation with this speaker and I failed. I mainly go for the small size and 40Hz tuning 🙂
Luuker , initially i can see that your B&C driver looks superb in a 100 liter tapped horn , roughly 3.15:1 compression ratio and a 272 centimeter path length .... very little offset with L12 and L45 set at 15cm ... 68 volts ...
Could be made a little smaller but you lose some performance ...
Now I am no expert with Tapped Horns, but you know who is VERY good at making this exact sort of thing? Brian Steele here on DIYaudio ..... He has even created a really handy Excel spreadsheet that calculates out your multi-fold TH box giving you a diagram and panel sizes, cutsheet and all ..... Pretty much all the info you need to build your cabinet ... You should ask him about it .. 🙂
Luuker ,
Take a look at this link, it is on Brian's website ..... You can see how he used the spreadsheet , and you can see his fold style along with what the cabinet actually looks like ..... The cabinet featured on this particular web page is about 100 liters net and tuned to 40hz .... If i remember right the compression ratio and path length are adjustable in his spreadsheet ...
The Subwoofer DIY Page v1.1 - Projects : "Proof of Concept #3"
Take a look at this link, it is on Brian's website ..... You can see how he used the spreadsheet , and you can see his fold style along with what the cabinet actually looks like ..... The cabinet featured on this particular web page is about 100 liters net and tuned to 40hz .... If i remember right the compression ratio and path length are adjustable in his spreadsheet ...
The Subwoofer DIY Page v1.1 - Projects : "Proof of Concept #3"
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So, a quick comparison between Xrk's 6th order BP and MMJ's OD-ML-Transflex:
Using a quick Excel spreadsheet to calculate volumes on the 6BP box, I arrived at outside dimensions of 18.5" x 16" x 15.5" Thats just 75.2 Liters!
(all upcoming judgments made based on sims)
With MMJ's box, the measurements were 36" x 13.5" x 10" giving just 79.6 Liters.
Extension: MMJ's box has a slight edge, it seems by about a 3Hz lower F3 than the bandpass box. Also, the location of the drivers motor in the mouth of the sub (while opening up the possibility for motor noise) should increase power handling and heat dissipation which seems to be what this driver needs most.
Output seems to be 1-2 dB better over the whole range with 2V less input on the Transflex box.
Convenience: While the Bandpass Box was only 4 Liters smaller, this was figured using 3/4 ply. Using 1/2", the box is only 70.5L external. This, along with absence of mass loading accounts for the slight drop in output and extension I would imagine. The 6BP box is much better for laying on its side and pole mounting a top on in a corner as well (more stable footprint, ports 90 degrees to one another to direct sound at 2 walls???)
Given my possession of 1/2" Baltic Birch, I am very keen on building both boxes and measuring them =) If I have a measurement mic from my Driverack PX, will that suffice or should I look into a different model? Can anyone recommend inexpensive measurement software? (College budget!)
Thanks everyone!
Using a quick Excel spreadsheet to calculate volumes on the 6BP box, I arrived at outside dimensions of 18.5" x 16" x 15.5" Thats just 75.2 Liters!
(all upcoming judgments made based on sims)
With MMJ's box, the measurements were 36" x 13.5" x 10" giving just 79.6 Liters.
Extension: MMJ's box has a slight edge, it seems by about a 3Hz lower F3 than the bandpass box. Also, the location of the drivers motor in the mouth of the sub (while opening up the possibility for motor noise) should increase power handling and heat dissipation which seems to be what this driver needs most.
Output seems to be 1-2 dB better over the whole range with 2V less input on the Transflex box.
Convenience: While the Bandpass Box was only 4 Liters smaller, this was figured using 3/4 ply. Using 1/2", the box is only 70.5L external. This, along with absence of mass loading accounts for the slight drop in output and extension I would imagine. The 6BP box is much better for laying on its side and pole mounting a top on in a corner as well (more stable footprint, ports 90 degrees to one another to direct sound at 2 walls???)
Given my possession of 1/2" Baltic Birch, I am very keen on building both boxes and measuring them =) If I have a measurement mic from my Driverack PX, will that suffice or should I look into a different model? Can anyone recommend inexpensive measurement software? (College budget!)
Thanks everyone!
is there a two chamber BP of modest size which will work with this cheap and cheerful dvc MCM driver? (I've probably got an ancient 9mm xmax Eminence 12 in my pile too but not sure of its Santoprene surround condition) http://www.mcmelectronics.com/product/55-1465
it could be fun to have a punchy helper woofer for my upcoming K10 midbass
Poly treated paper cone
Rubber surround
Stamped steel basket
2" voice coil
42.6oz. magnet
Specifications::
Power Capacity: 100W/200W RMS/peak (per coil)
Sensitivity: 93dB (W/M)
Impedance: 8ohm (per coil)
Re: 5.8ohm (per coil)
Le: 0.59mH (per coil)
Frequency response: 25Hz~3KHz
Fs: 25Hz
Qts: 0.30
Qes: 0.32
Qms: 3.13
Vas: 203.81 (liters)
Xmax: 5.0mm
it could be fun to have a punchy helper woofer for my upcoming K10 midbass
Poly treated paper cone
Rubber surround
Stamped steel basket
2" voice coil
42.6oz. magnet
Specifications::
Power Capacity: 100W/200W RMS/peak (per coil)
Sensitivity: 93dB (W/M)
Impedance: 8ohm (per coil)
Re: 5.8ohm (per coil)
Le: 0.59mH (per coil)
Frequency response: 25Hz~3KHz
Fs: 25Hz
Qts: 0.30
Qes: 0.32
Qms: 3.13
Vas: 203.81 (liters)
Xmax: 5.0mm
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The link does not take you directly to the sub - you will need to look for P/N 55-1465
Hey there Freddi ,
Do you have a DATS or some other sort of woofer tester that you can use to test the MCM? MCM's driver are notorious for having specs that are far different from the published specs, and sometimes that can be a good thing! 🙂 For example , you might find that your MCM woofer has a VAS half that large and an FS in the 35-45hz range , which would be much better for these sorts of designs ..
Let us know if that Eminence turns out to have a good surround , that could have good potential as sub if it has at least as much XMAX as the MCM ..