apologies in advance if anything sounds vague....
I`m wanting to build a smallish sub to complement my micro system for listening to music. But I`m having trouble trying to decide what to build that won`t be overkill. I don`t consider myself an audiophile but I like a nice clean sound.
1. What kind of curve should the sub have? flat , peak at some frerq., or other? I've looked at various designs but they won`t really tell me anything about the final sound and how loud/effective it will be.
being a poor student , I can't really experiment too much so I`m trying to determine what would suit my needs best in advance.
Also, I don`t need a lot volume, my living area is fairly small at the moment. The micro system fills it nicely without cranking it up ( except for bass of course.
Thanks for looking and hopefully making a suggestion or two.
Subs I have to play with are:
eclipse 8122.4 12" sub
fs: 23hz
qts: 0.355
Vas: 8 cubic ft.
Z:4 ohm
DCR: 3.6
xmax(one way) : 0.177in
pe: 150W
sd (approx): 550 sq.cm.
91db sens.
or:
max pentivent 1030
fs: 19hz
qts: 0.35
qes: .37
qms 3.6
Vas: 4.6cubic ft.
Z:4 ohm
DCR: 2.9
xmax(one way) : +/- 4mm
pe: 125W
sd (approx): 360 sq.cm.
85db sens.
I`m wanting to build a smallish sub to complement my micro system for listening to music. But I`m having trouble trying to decide what to build that won`t be overkill. I don`t consider myself an audiophile but I like a nice clean sound.
1. What kind of curve should the sub have? flat , peak at some frerq., or other? I've looked at various designs but they won`t really tell me anything about the final sound and how loud/effective it will be.
being a poor student , I can't really experiment too much so I`m trying to determine what would suit my needs best in advance.
Also, I don`t need a lot volume, my living area is fairly small at the moment. The micro system fills it nicely without cranking it up ( except for bass of course.
Thanks for looking and hopefully making a suggestion or two.
Subs I have to play with are:
eclipse 8122.4 12" sub
fs: 23hz
qts: 0.355
Vas: 8 cubic ft.
Z:4 ohm
DCR: 3.6
xmax(one way) : 0.177in
pe: 150W
sd (approx): 550 sq.cm.
91db sens.
or:
max pentivent 1030
fs: 19hz
qts: 0.35
qes: .37
qms 3.6
Vas: 4.6cubic ft.
Z:4 ohm
DCR: 2.9
xmax(one way) : +/- 4mm
pe: 125W
sd (approx): 360 sq.cm.
85db sens.
I would take the Eclipse and put it into a 2 Ft³sealed box. It should work out fine.
With the small excursion of the Eclipse, I would hesitate to put it into a sealed enclosure. However, there does not seem to be a good way to port it without making a big box.
The Eclipse is 6 dB more sensitive than the Max Pentivent. That is very significant.
With the small excursion of the Eclipse, I would hesitate to put it into a sealed enclosure. However, there does not seem to be a good way to port it without making a big box.
The Eclipse is 6 dB more sensitive than the Max Pentivent. That is very significant.
Horses for courses
Just to put a different slant on KC's suggestion.
As its a micro system with limited SPL capability I'd suggest the
Pentivent is a better bet. At low frequencies power handling is
excursion limited and it has better excursion, i.e. it will produce
more low bass.
It will need only nearly half the box volume of the Pentivent,
mainly due to the diffrence in Sd causing the diffrence in Vas.
The 100W or so of a sub amplifier will be better utilised.
Converting your micro system speakers to sealed box may help.
A stuffed sealed box with Q around 0.6 will be fine.
For the two drivers ~ :
Eclipse : Volume = 3.5cuFt, Fb = 42Hz.
Pentivent : V = 2.2cuFt, Fb = 33Hz.
If a near 0.71 alignment is used ~ :
E : Vb=2.5cuFt, Fb=47Hz.
P : Vb=1.5cuFt, Fb= 38Hz.
The trade off is efficiency vs. box volume and extension, I suggest
with a 100w sub amplifier its power that you have going spare.
sreten.
Just to put a different slant on KC's suggestion.
As its a micro system with limited SPL capability I'd suggest the
Pentivent is a better bet. At low frequencies power handling is
excursion limited and it has better excursion, i.e. it will produce
more low bass.
It will need only nearly half the box volume of the Pentivent,
mainly due to the diffrence in Sd causing the diffrence in Vas.
The 100W or so of a sub amplifier will be better utilised.
Converting your micro system speakers to sealed box may help.
A stuffed sealed box with Q around 0.6 will be fine.
For the two drivers ~ :
Eclipse : Volume = 3.5cuFt, Fb = 42Hz.
Pentivent : V = 2.2cuFt, Fb = 33Hz.
If a near 0.71 alignment is used ~ :
E : Vb=2.5cuFt, Fb=47Hz.
P : Vb=1.5cuFt, Fb= 38Hz.
The trade off is efficiency vs. box volume and extension, I suggest
with a 100w sub amplifier its power that you have going spare.
sreten.kelticwizard said:
Just for comparison, doing a 2 cu.ft. vented, tuned to 35hz, VS a 2cu.ft. sealed(yellow) would look like this. Would a curve like this sound bad?
I`ll be tracking down that speaker design book thats been mentioned here before. That should help, no??
Attachments
Re: Horses for courses
There seems to be some contradictions/confusion for me here...
Actually the eclipse has better excursion at 4.5mm vs 4mm one way. Or am I reading that wrong?
I`m assuming the pentivent only needs half the box vol. to what the eclipse needs.
How do you determine Q?
This I understand, wellll except maybe how you decided on the
.71 alignment
There seems to be some contradictions/confusion for me here...
sreten said:
Actually the eclipse has better excursion at 4.5mm vs 4mm one way. Or am I reading that wrong?
I`m assuming the pentivent only needs half the box vol. to what the eclipse needs.
How do you determine Q?
For the two drivers ~ :
Eclipse : Volume = 3.5cuFt, Fb = 42Hz.
Pentivent : V = 2.2cuFt, Fb = 33Hz.
If a near 0.71 alignment is used ~ :
E : Vb=2.5cuFt, Fb=47Hz.
P : Vb=1.5cuFt, Fb= 38Hz.
The trade off is efficiency vs. box volume and extension, I suggest
with a 100w sub amplifier its power that you have going spare.
This I understand, wellll except maybe how you decided on the
.71 alignment
Theli,
the curve of the vented box you showed doesn't look good - the tuning is too high and there is a bump in the response, so that its response it exaggerated at one point without really giving a significant gain over the sealed box - not a good design. Try tuning lower, closer to fs - more like 23 Hz as a starting point. Get the best looking response, and make a chart showing for your 2cu ft box both drivers vented and sealed. This would enable a better comparison, but it would seem to me a vented box would be the best way to go. All other things being equal, more efficient is better, but this doesn't always help for a subwoofer, as low end efficiency is determined by more than just the nominal efficiency.
regards,
Paul
PS - based on comments above, I don't think a satisfactory conclusion has been drawn as you need to compare on the basis of a simulation that shows the impact all the relevant factors - picking out numbers and comparing them won't really help you.
the curve of the vented box you showed doesn't look good - the tuning is too high and there is a bump in the response, so that its response it exaggerated at one point without really giving a significant gain over the sealed box - not a good design. Try tuning lower, closer to fs - more like 23 Hz as a starting point. Get the best looking response, and make a chart showing for your 2cu ft box both drivers vented and sealed. This would enable a better comparison, but it would seem to me a vented box would be the best way to go. All other things being equal, more efficient is better, but this doesn't always help for a subwoofer, as low end efficiency is determined by more than just the nominal efficiency.
regards,
Paul
PS - based on comments above, I don't think a satisfactory conclusion has been drawn as you need to compare on the basis of a simulation that shows the impact all the relevant factors - picking out numbers and comparing them won't really help you.
Re: Re: Horses for courses
A) I read it as 8mm vs 4.5mm
B) Q and F are raised by square root (Vas/Vb+1)
C) Q=0.71 is the classic maximally flat Butterworth alignment.
sreten.
Theli said:There seems to be some contradictions/confusion for me here...
Actually the eclipse has better excursion at 4.5mm vs 4mm one way. Or am I reading that wrong?
I`m assuming the pentivent only needs half the box vol. to what the eclipse needs.
How do you determine Q?
This I understand, wellll except maybe how you decided on the
.71 alignment
A) I read it as 8mm vs 4.5mm
B) Q and F are raised by square root (Vas/Vb+1)
C) Q=0.71 is the classic maximally flat Butterworth alignment.
sreten.
Sreten,
Both drivers are specified as having a one way xmax, so it should be 4.5mm vs 4 mm, not a significant difference.
It appears that you didn't show vented for both drivers.
Theli
From Sreten's chart, it appears that there is +3db at 40 Hz and about +5db at 30 Hz. At this point you will have higher power handling and increased output, however, the power will probably be more determined by the cone excursion above tuning for most music. The vented box gives you more output, and this may be important with a sub that doesn't have much xmax. It depends on your tastes and priorities. When you put it in a room, you will get a boost and this is likely to mess up the response of the vented box the most. With the smoother rolloff of the sealed sub, the boost from the room, especially if you put it in a corner, will be extended lower. You will probably get all the extension that you need for music. The sealed box is more likely to give you more articulate and accurate bass. If a vented box sounds boomy in the corner, you might move it out from the corner, or into the centre of the room if possible - try experimenting.
Is it possible for you to try a vent, then try plugging it with your box? That way you get to decide which you like best, and hear how it sounds in your actual room. You are the expert at what sounds best to your ears.
regards,
Paul
Both drivers are specified as having a one way xmax, so it should be 4.5mm vs 4 mm, not a significant difference.
It appears that you didn't show vented for both drivers.
Theli
From Sreten's chart, it appears that there is +3db at 40 Hz and about +5db at 30 Hz. At this point you will have higher power handling and increased output, however, the power will probably be more determined by the cone excursion above tuning for most music. The vented box gives you more output, and this may be important with a sub that doesn't have much xmax. It depends on your tastes and priorities. When you put it in a room, you will get a boost and this is likely to mess up the response of the vented box the most. With the smoother rolloff of the sealed sub, the boost from the room, especially if you put it in a corner, will be extended lower. You will probably get all the extension that you need for music. The sealed box is more likely to give you more articulate and accurate bass. If a vented box sounds boomy in the corner, you might move it out from the corner, or into the centre of the room if possible - try experimenting.
Is it possible for you to try a vent, then try plugging it with your box? That way you get to decide which you like best, and hear how it sounds in your actual room. You are the expert at what sounds best to your ears.
regards,
Paul
Tuning a port to 22Hz needs a massive vent and tuning is critical,
in practice this is very difficult to effectively achieve without measuring.
I prefer overdamped reflex alignments, this is not possible
with either driver you are considering, IMO the maximally
flat reflex alignment as shown will give poor in-room bass.
You stated volume capabilility is not an issue, so IMO a compact
sealed box is your best bet with the Pentivent. Around 50litres.
As shown, box volume is not a critical issue with sealed boxes.
BTW you don't mention the cost of the drivers, there may be
better options. Or the sub amplifier you are considering.
sreten.
in practice this is very difficult to effectively achieve without measuring.
I prefer overdamped reflex alignments, this is not possible
with either driver you are considering, IMO the maximally
flat reflex alignment as shown will give poor in-room bass.
You stated volume capabilility is not an issue, so IMO a compact
sealed box is your best bet with the Pentivent. Around 50litres.
As shown, box volume is not a critical issue with sealed boxes.
BTW you don't mention the cost of the drivers, there may be
better options. Or the sub amplifier you are considering.
sreten.
Depends on what you call "massive" and what diameter vent you use. A 90mm vent in a 2 cu ft box would need to be 640mm long, yes that would be massive. But instead if a 70mm flared vent (both ends) were used tuned a little higher, say 24 Hz, would be 310mm, which is not so bad.
I don't see why measuring is essential for a vented box. It is certainly helpful, but the differences arising from the parameters being different to the specs aren't likely to make the design a failure. Playing around with different numbers will give an idea of how sensitive the design is to a less than optimum design.
Perhaps a sealed box is the best way to go, and if you were to build from scratch, you might chooose this, given that you said SPL wasn't a big issue - and sealed does allow a smaller box. But since you already have a box that is reasonably large, why not try both?
If it sounds good do it ... if it doesn't, don't!
I don't see why measuring is essential for a vented box. It is certainly helpful, but the differences arising from the parameters being different to the specs aren't likely to make the design a failure. Playing around with different numbers will give an idea of how sensitive the design is to a less than optimum design.
Perhaps a sealed box is the best way to go, and if you were to build from scratch, you might chooose this, given that you said SPL wasn't a big issue - and sealed does allow a smaller box. But since you already have a box that is reasonably large, why not try both?
If it sounds good do it ... if it doesn't, don't!
sreten said:Tuning a port to 22Hz needs a massive vent and tuning is critical,
in practice this is very difficult to effectively achieve without measuring.
I prefer overdamped reflex alignments, this is not possible
with either driver you are considering, IMO the maximally
flat reflex alignment as shown will give poor in-room bass.
You stated volume capabilility is not an issue, so IMO a compact
sealed box is your best bet with the Pentivent. Around 50litres.
As shown, box volume is not a critical issue with sealed boxes.
BTW you don't mention the cost of the drivers, there may be
better options. Or the sub amplifier you are considering.
Well, the eclipse is free, since I`ve had it for a few years in my car and the pentivent was about $50 CDN. The best deals for sub amps was the Apex Jr. Sub Amp. Also there is one from Solen.ca or Creative sound solutions (Sub-100 amp, but i don`t know much about that one really)
paulspencer said:
I messed up on the box size, it`s actually about 1.5 cu.ft (~ 42 ltr)
I`m getting a SPL meter from a friend to determine what kind of sound levels I actually listen to at home. Would this help?
Measuring the levels you listen to probably won't help you much with choosing between a sealed and vented sub. For the range covered by music (mostly above 40 Hz) the output from a sealed will not be much less - only 3db. Room placement and the acoustics of the room itself will actually be more significant. If your system is a typical mini system then my guess is that in a small room, either sub will have plenty of SPL.
In a 42L box it becomes harder to get in a decent vent.
In a 42L box it becomes harder to get in a decent vent.
After much playing around with different subs and reading the info on this forum, I`ve decided to go with the max pentivent and a 1cu ft (28ltr) sealed enclosure maybe with some stuffing. Makes it easy to build and should put out enough bass. AND be cheap to make.
a big thank you to everyone.
a big thank you to everyone.
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