Yello!
I'm building a home theater subwoofer. I have managed to get hold of 8x cheap Logitech Z-2300 sound systems. I'm going to take their subwoofers and put in a new enclosure. I am 99% sure that the Z-2300 subwoofers are the same as a Tang Band W8-670C (see pdf below). Could someone help me design an enclosure with as low a tuning frequency as possible.
These subwoofers have the FS at 40Hz, is it then possible to tune a enclosure below this or what will happen then?
The place I have is 2,478mm wide, 450mm high and max 500mm depth. (It will be under the projector screen)
Thanks
//Rian
I'm building a home theater subwoofer. I have managed to get hold of 8x cheap Logitech Z-2300 sound systems. I'm going to take their subwoofers and put in a new enclosure. I am 99% sure that the Z-2300 subwoofers are the same as a Tang Band W8-670C (see pdf below). Could someone help me design an enclosure with as low a tuning frequency as possible.
These subwoofers have the FS at 40Hz, is it then possible to tune a enclosure below this or what will happen then?
The place I have is 2,478mm wide, 450mm high and max 500mm depth. (It will be under the projector screen)
Thanks
//Rian
With 8 drivers you want to build 4 push-push woofers, and use the multitude to deal with room response.
Home theatre woofers are often called”atmosphere generators” and go low, but often poorly.
Do not expect these to do the most dramatic train-wrecks and such, but it sounds an interesting project. I have little experience with that TB, but there are many i suspect who will chime in with their experiences.
dave
Home theatre woofers are often called”atmosphere generators” and go low, but often poorly.
Do not expect these to do the most dramatic train-wrecks and such, but it sounds an interesting project. I have little experience with that TB, but there are many i suspect who will chime in with their experiences.
dave
Sure it's not the W8-470p that DSL uses (used?) in their TH 'SPUD'?
As a general rule, not a good plan to tune a driver < ~0.707x Fs (1/2 octave).
As a general rule, not a good plan to tune a driver < ~0.707x Fs (1/2 octave).
There is other data where people have measured the Logitech driver.
The mechanical values are all slightly different. FS seems consistent, and the Gap height
is consistent.
Numerous different drivers in the 670 series, All about the same ish. 38-40 Hz Fs about 7mm xmax.
Mechanical properties are going to lead to a basic 18 to 22 liter box. Like many other 8" drivers with
similar mechanical abilities Tuned slightly above Fs 42 to 45 Hz
I looked at that 470 series driver. It is a much more larger magnet and more elaborate coil venting.
Looking at few disassembly videos of the Logitech sub.
Does appear close to the 670 series, same magnet and rear venting/basket etc etc
Running the actual 670C, a basic QB3 alignment seems to be the best
18.6 liters 42 Fb
You can tune lower, but bass response can be lower.
Often to tune about 10 Hz lower. The enclosure is made larger which will create a " Shelf" response
which sits at -3 dB. So technically it goes lower. But the shelf sits at -3dB.
The alignment is called Extended Bass Shelf
Tradeoff is larger box and power handling is reduced.
Below is transfer function of QB3 ( Quasi Butterworth 3rd order) =Grey plot 18.6 liters 42.5 Fb
EBS3 ( Extended Bass Shelf -3dB)= Green plot 38.28 liters 31.6 Fb
The mechanical values are all slightly different. FS seems consistent, and the Gap height
is consistent.
Numerous different drivers in the 670 series, All about the same ish. 38-40 Hz Fs about 7mm xmax.
Mechanical properties are going to lead to a basic 18 to 22 liter box. Like many other 8" drivers with
similar mechanical abilities Tuned slightly above Fs 42 to 45 Hz
I looked at that 470 series driver. It is a much more larger magnet and more elaborate coil venting.
Looking at few disassembly videos of the Logitech sub.
Does appear close to the 670 series, same magnet and rear venting/basket etc etc
Running the actual 670C, a basic QB3 alignment seems to be the best
18.6 liters 42 Fb
Running the numbers of posted data sheet driver works best in QB3 alignment 18.6 liters, tuned to 42.5 Hz
You can tune lower, but bass response can be lower.
Often to tune about 10 Hz lower. The enclosure is made larger which will create a " Shelf" response
which sits at -3 dB. So technically it goes lower. But the shelf sits at -3dB.
The alignment is called Extended Bass Shelf
Tradeoff is larger box and power handling is reduced.
Below is transfer function of QB3 ( Quasi Butterworth 3rd order) =Grey plot 18.6 liters 42.5 Fb
EBS3 ( Extended Bass Shelf -3dB)= Green plot 38.28 liters 31.6 Fb
Agreed, I never cared for Extended Bass Shelf. Not much benefit with the mechanical ability of this driver
and many others.
If you want lower tuning, you need to use a driver with lower Fs.
I was just giving a more basic visual representation to the OP. So he could see , not much benefit in tuning below Fs.
Of course there is exceptions.
Within basic generalization, free air resonance is about the end of the road.
and many others.
If you want lower tuning, you need to use a driver with lower Fs.
I was just giving a more basic visual representation to the OP. So he could see , not much benefit in tuning below Fs.
Of course there is exceptions.
Within basic generalization, free air resonance is about the end of the road.
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Ok I understand.
Probably not worth it to tune below FS then.
What about the port size and etc when using 8 of those.
Probably not worth it to tune below FS then.
What about the port size and etc when using 8 of those.
It might be possible to get it around 0db. Because I would have room for a 549 liter enclosure which would be 68.6 liters per subwoofer. I'm a little interested in this push-push idea of what benefits does this have?
It would be a long post to describe function and design for push pull.
To read up and research the topic " Isobaric Loading "
Your doubling mechanical properties of driver. so the required volume is cut in half.
suitable for drivers which require extremely large airspace.
https://www.kicker.com/how-to-build-a-subwoofer-box
You need to familiarize yourself with box calculators like VituixCad https://kimmosaunisto.net/or Winisd http://www.linearteam.org/
and many other, so you can calculate vent length.
If your box is going to be 18 liter according to simulator net volume. Gross volume will be larger
since bracing , port and driver displace volume. So Gross volume will be larger to make up for what they displace.
To read up and research the topic " Isobaric Loading "
Your doubling mechanical properties of driver. so the required volume is cut in half.
suitable for drivers which require extremely large airspace.
https://www.kicker.com/how-to-build-a-subwoofer-box
You need to familiarize yourself with box calculators like VituixCad https://kimmosaunisto.net/or Winisd http://www.linearteam.org/
and many other, so you can calculate vent length.
If your box is going to be 18 liter according to simulator net volume. Gross volume will be larger
since bracing , port and driver displace volume. So Gross volume will be larger to make up for what they displace.
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Sounds like a fun project.
Recently added a pair of Warfdale subs to the hi-fi for a larger sound in films than the Elsinores can handle. Because films on a nice big projector screen need rumble..
They initially didnt cut it. Bigger sound but terrible and uneven response. So ripped out the port and blocked the hole, then filled with more stuffing. This gave a response that rolled off evenly, but the tuning is too high. DSP fixed it. Wheras I was having a hard time using the DSP to currect them when ported.
Would suggest making a pair of sensibly sized sealed cabinets and also cheating with a DSP. I'm just using a Mini-DSP 2x4 recycled from another project.
Recently added a pair of Warfdale subs to the hi-fi for a larger sound in films than the Elsinores can handle. Because films on a nice big projector screen need rumble..
They initially didnt cut it. Bigger sound but terrible and uneven response. So ripped out the port and blocked the hole, then filled with more stuffing. This gave a response that rolled off evenly, but the tuning is too high. DSP fixed it. Wheras I was having a hard time using the DSP to currect them when ported.
Would suggest making a pair of sensibly sized sealed cabinets and also cheating with a DSP. I'm just using a Mini-DSP 2x4 recycled from another project.