Hi guys
I’m planning to build my first subwoofer. The problem is that I don’t know anything technical. Of course I can just choose anything on the internet but I like to know what I’m doing.
So here’s my question.
There are a lot of technical specs. I don’t know how to read this. Where do I start learning this?
Here’s a list chosen from the Madison site. MA26WR09-04 10” Black Aluminum cone woofer
.
Vifa 10” Black Aluminum cone woofer
Rubber surround
Magnesium cast frame
Double magnet
F3 of 33Hz in 1.5 cubic foot sealed box!
Flange 271mm
Cut-out 231.2mm
Depth 124mm
Excellent for home or autosound
Very tight bass
Znom 4 ohm
Re 3.44 ohm
Le@1kHz 1.2 mH
fs 21 Hz
Qms 3.53
Qes 0.52
Qts 0.46
Mms 149.3 g
Cms 384.8 mm/N
Sd 333.0 cm2
BL 11.3 Tm
Vas 60.6 ltrs
Xmax 11.6 mm peak
VC Ø 50 mm
Sensitivity
2.83V / 1m 83.3 dB
Nom. Power DIN 300 W
Magnet weight 2.1 kg
I’m planning to build my first subwoofer. The problem is that I don’t know anything technical. Of course I can just choose anything on the internet but I like to know what I’m doing.
So here’s my question.
There are a lot of technical specs. I don’t know how to read this. Where do I start learning this?
Here’s a list chosen from the Madison site. MA26WR09-04 10” Black Aluminum cone woofer
.
Vifa 10” Black Aluminum cone woofer
Rubber surround
Magnesium cast frame
Double magnet
F3 of 33Hz in 1.5 cubic foot sealed box!
Flange 271mm
Cut-out 231.2mm
Depth 124mm
Excellent for home or autosound
Very tight bass
Znom 4 ohm
Re 3.44 ohm
Le@1kHz 1.2 mH
fs 21 Hz
Qms 3.53
Qes 0.52
Qts 0.46
Mms 149.3 g
Cms 384.8 mm/N
Sd 333.0 cm2
BL 11.3 Tm
Vas 60.6 ltrs
Xmax 11.6 mm peak
VC Ø 50 mm
Sensitivity
2.83V / 1m 83.3 dB
Nom. Power DIN 300 W
Magnet weight 2.1 kg
Hi,
picking out a few lines from the spec will help you read the information.
F3 of 33Hz in 1.5 cubic foot sealed box!
tells you what to expect for bass extension (this will suit music but less good with film sound effects)
Znom 4 ohm
needs an amplifier that is capable of driving a reactive 4ohm load
fs 21 Hz
allows you to design a cabinet.
Qts 0.46
tells you not to use a vented cabinet.
BL 11.3 Tm
tells you it has a medium strength motor.
Vas 60.6 ltrs
allows you to design a cabinet.
Xmax 11.6 mm peak
combined with the Sd, can be used to estimate the lowest frequency and SPL the driver can achieve (particularly important if you decide to equalise for deeper bass).
2.83V / 1m 83.3 dB
tells you it is atrocious.
picking out a few lines from the spec will help you read the information.
F3 of 33Hz in 1.5 cubic foot sealed box!
tells you what to expect for bass extension (this will suit music but less good with film sound effects)
Znom 4 ohm
needs an amplifier that is capable of driving a reactive 4ohm load
fs 21 Hz
allows you to design a cabinet.
Qts 0.46
tells you not to use a vented cabinet.
BL 11.3 Tm
tells you it has a medium strength motor.
Vas 60.6 ltrs
allows you to design a cabinet.
Xmax 11.6 mm peak
combined with the Sd, can be used to estimate the lowest frequency and SPL the driver can achieve (particularly important if you decide to equalise for deeper bass).
2.83V / 1m 83.3 dB
tells you it is atrocious.
Re: Re: Sub technical spec.
Hi,
Hardly the case. It tells you you need plenty of power to reach Xmax
and that you have chosen a driver that gives very good bass in a
small enclosure at the cost of sensitivity.
A driver with the same performance but say 86dB would need
a amplifier with half the power but need a box twice as big.
Horses for courses ........
/sreten.
AndrewT said:
Hi,
Hardly the case. It tells you you need plenty of power to reach Xmax
and that you have chosen a driver that gives very good bass in a
small enclosure at the cost of sensitivity.
A driver with the same performance but say 86dB would need
a amplifier with half the power but need a box twice as big.
Horses for courses ........
/sreten.Andrew T
I agree with sreten because: As sensitivity in dB is =112 + log No and the efficiency-bandwidth-volume equation is No = kn Vb f3^3.
This equation tells you that for a given efficiency, the efficiency constant No only depends on system order and (if) alignment and for a given driver, you can only trade volume requirement against f3.
But if No is held constant and one chose to alter the efficiency you are then free change both volume and f3.
It follows as sreten wrote: 'Horses for courses'; double No, 10 log No = + 3 dB implies 2xNo=kn (2 x Vb) f3^3 and as a consequence: is also valid for the driver in focus with 83 dB SPL/1m + 3 dB.
B
I agree with sreten because: As sensitivity in dB is =112 + log No and the efficiency-bandwidth-volume equation is No = kn Vb f3^3.
This equation tells you that for a given efficiency, the efficiency constant No only depends on system order and (if) alignment and for a given driver, you can only trade volume requirement against f3.
But if No is held constant and one chose to alter the efficiency you are then free change both volume and f3.
It follows as sreten wrote: 'Horses for courses'; double No, 10 log No = + 3 dB implies 2xNo=kn (2 x Vb) f3^3 and as a consequence: is also valid for the driver in focus with 83 dB SPL/1m + 3 dB.
B
Hi,
I can see the relationship in a complete speaker assembly. No disagreement. I had not realised there was a formula tying that lot together.
My question related to the basic driver parameters.
If sensitivity is increased and the parameters that follow that increase are altered, will the new sensitivity also DEMAND that the box volume increase pro rata.
I don't know and I cannot recall seeing a similar correlation
I can see the relationship in a complete speaker assembly. No disagreement. I had not realised there was a formula tying that lot together.
My question related to the basic driver parameters.
If sensitivity is increased and the parameters that follow that increase are altered, will the new sensitivity also DEMAND that the box volume increase pro rata.
I don't know and I cannot recall seeing a similar correlation
Hi Andrew,
I focused on ‘small enclosure at the cost of sensitivity’ thus system No.
The speaker specification mentioned a 1.5 cubic foot sealed box at an f3 of 33 Hz and I took that for an input parameter too.
For this case it narrows everything down for the specific driver in an enclosure and ‘No = kn Vb f3^3’ is the only equation one needs to tamper with.
The No in’ sensitivity in dB is =112 + log No’ is not same as No in ‘No = kn Vb f3^3’.
The first is driver No and the latter is system No.
But once within a driver specification and when not in prior deciding for system requirements like f3, Vb and so on, then there is a lot of parameters that can affect driver No: No = k x fs^3 x Vas/Qes.
You can double Vas or increase fs by about 26 % or lower Qes 50% or in any combination of fs/Vas/Qes to meet a decision of doubling the No(driver).
Now it looks like I agree with all of you including richieOOboy.
B
I focused on ‘small enclosure at the cost of sensitivity’ thus system No.
The speaker specification mentioned a 1.5 cubic foot sealed box at an f3 of 33 Hz and I took that for an input parameter too.
For this case it narrows everything down for the specific driver in an enclosure and ‘No = kn Vb f3^3’ is the only equation one needs to tamper with.
The No in’ sensitivity in dB is =112 + log No’ is not same as No in ‘No = kn Vb f3^3’.
The first is driver No and the latter is system No.
But once within a driver specification and when not in prior deciding for system requirements like f3, Vb and so on, then there is a lot of parameters that can affect driver No: No = k x fs^3 x Vas/Qes.
You can double Vas or increase fs by about 26 % or lower Qes 50% or in any combination of fs/Vas/Qes to meet a decision of doubling the No(driver).
Now it looks like I agree with all of you including richieOOboy.
B
Hi,
Semantics scmantics.
None of you are now making sense. Its a good driver for purpose.
All the parameters are interelated and magically doubling efficiency
is hardly an arguement, your talking about doubling the magnet size.
For a given magnet and excursion capability you increase efficiency by
reducing cone mass, for the same Fs you increase Vas = a bigger box.
Generally : spend more and you get a better driver.
GW : driver selection depends on a number of constraints - mainly
budget and what is deemed an acceptable box size, noting that
smallish subs and expensive drivers need expensive amplifiers.
Related to the above is acceptable SPL depending on application.
parts express sub drivers have near ideal parameters for cost.
But if you want something small or very large then ...........
/sreten.
Semantics scmantics.
None of you are now making sense. Its a good driver for purpose.
All the parameters are interelated and magically doubling efficiency
is hardly an arguement, your talking about doubling the magnet size.
For a given magnet and excursion capability you increase efficiency by
reducing cone mass, for the same Fs you increase Vas = a bigger box.
Generally : spend more and you get a better driver.
GW : driver selection depends on a number of constraints - mainly
budget and what is deemed an acceptable box size, noting that
smallish subs and expensive drivers need expensive amplifiers.
Related to the above is acceptable SPL depending on application.
parts express sub drivers have near ideal parameters for cost.
But if you want something small or very large then ...........
/sreten.Globalweb:
If you are really serious about learning, then you probably should stop listening to partial answers - which is sort of like half-truths. This will not get you very far and often in the wrong direction. You'll wonder who is right as the "experts" argue with each other.
Start with some good math skills. To really understand what is going on in a quantitative sense, you need to be pretty limber with the numbers. Get Testing Loudspeakers by Joe D'Appolito (about $35 US) and READ it. This will get you started. If you want to be truly expert AND you are pretty good at calculus, then get Audio Transducers by Earl Geddes (about $70 US - seriously math heavy acedemic treatment) and Loudspeaker Handbook by John Eargle (about $140 US - lots of real world examples.) If you read and understand these books, then for about $245 you will have an Audio Transducer education which will put most "high-end" "designers" and "engineers" (you know - the ones that tune by ear) to shame. Sorry, but this is a field where the answers are not always simple.
If you are really serious about learning, then you probably should stop listening to partial answers - which is sort of like half-truths. This will not get you very far and often in the wrong direction. You'll wonder who is right as the "experts" argue with each other.
Start with some good math skills. To really understand what is going on in a quantitative sense, you need to be pretty limber with the numbers. Get Testing Loudspeakers by Joe D'Appolito (about $35 US) and READ it. This will get you started. If you want to be truly expert AND you are pretty good at calculus, then get Audio Transducers by Earl Geddes (about $70 US - seriously math heavy acedemic treatment) and Loudspeaker Handbook by John Eargle (about $140 US - lots of real world examples.) If you read and understand these books, then for about $245 you will have an Audio Transducer education which will put most "high-end" "designers" and "engineers" (you know - the ones that tune by ear) to shame. Sorry, but this is a field where the answers are not always simple.
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