Thx weltersys. I'm using 4 woofers per cab and I'm not exceeding 100 watts per woofer so 119db will be the limit. I was wondering what the db gain would b if I build another cab with identical specs(4 woofers with 100Watts per woofer). Would I get 119 + 12(4 woofers x +3db) = 131db spl + 3db transfer function of the floor?
I missed your reply forr....just read it.....let me give u my exact setup. 1 Bash plate amp [www.parts-express.com/bash-500s-digital-subwoofer-plate-amplifier-500w-rms--300-752]. 4 Dayton Audio 12" [www.parts-express.com/dayton-audio-dcs305-4-12-classic-subwoofer-4-ohm--295-204]. I am wiring each pair in series to give me 8ohms then both pairs in parallel to give me 4ohms. I also have an EP4000 that I can use but I don't wanna use because I want a self powered cab. What's the max spl from that setup Forr?
If I understand it correctly, you would only get a 3db gain if you added 1 driver to 1 driver, i.e. doubled them. (Assuming you do not add any additional power.)
Therefore, if you have 2 drivers already you will need to add 2 more to get +3dB (assuming power into the system does not change), 4 drivers you will need to add 4 more drivers, etc.
+3dB means you have to double the drivers, however many you already have.
+3dB is also achievable if you double the power.
So to get 6dB gain, you will have to add 4 more drivers to your existing 4 (+3dB) and then add another amplifier to the same power as your existing amplifier (+3dB).
Oh no !
If, everything being equal, the emitting area is doubled,
you get 6 dB when connected in parallel
and 0 dB when connected in series.
You apply voltage to drivers, not power.
With two drivers :
In parallel, with the 6 dB SPL increase, current and power are doubled.
In series, with no dB increase, current and power are halved.
In both cases, due to mutual coupling, the efficiency is doubled.
You do not need to have separate for each cabinet,
Anyway, it does not change the calculated values.
"each pair in series to give me 8ohms then both pairs in parallel to give me 4ohms" is right
Currently, your links do not function for me.
To calculate the theoretical max SPL of your loudspeaker with 4 drivers,
we need to know the initial nominal efficiency of one driver
and the amp nominal power in a specified load.
Dayton Audio DCS305-4 12" Classic
Subwoofer 4 Ohm. Nominal Diameter 12"
Power Handling (RMS) 250 Watts
Power Handling (max) 500 Watts
Impedance 4 ohms
Frequency Response 23 to 200 Hz
Sensitivity 89.4 dB 1W/1m
Voice Coil Diameter 2.57"
Resonant Frequency (Fs) 23 Hz
DC Resistance (Re) 3.2 ohms
Voice Coil Inductance (Le) 1.94 mH
Mechanical Q (Qms) 5.59
Electromagnetic Q (Qes) 0.44
Total Q (Qts) 0.41
Compliance Equivalent Volume (Vas) 4.12 ft.³
Mechanical Compliance of Suspension
(Cms) 0.33 mm/N
BL Product (BL) 12.31 Tm
Diaphragm Mass Inc. Airload (Mms) 145g
Maximum Linear Excursion (Xmax) 9.3 mm
Surface Area of Cone (Sd) 498.8 cm²
--------------------------------------------------------------Bash 500S Digital Subwoofer Plate
Amplifier 500W RMS
Specifications:
• 500 watts RMS @ 0.5% THD into 4 ohm
load
• Signal to noise ratio: 105 dB (A-
weighted)
• Dimensions: 12" W x 8" H x 3-1/2" D
• Cabinet cutout: 11" x 7"
• Line-in and high-level in crossovers:
Adjustable 50 to 150 Hz, 12 dB/
octave low-pass crossover, a fixed 230
Hz, 12 dB/octave low-pass crossover,
and a fixed 330 Hz, 12 dB/octave low-
pass crossover
• Two stacked LFE-in crossovers: A fixed
230 Hz, 12 dB/octave low-pass
crossover, and a fixed 330 Hz, 12 dB/
octave low-pass crossover
-------------------------------------------------------------- I wanna build 2 cabs: 4 woofers each with a slot port at the bottom tuned between 27-32Hz. Each cab has a Bash 500watt Plate amp powering it. My reason for choosing home woofers is: from my calculations pro woofers only give me 1Watt efficiency from 50Hz up, I wanna avoid power compression, I play lots of music with 30Hz notes, most of my WinIsd/Unibox modeling show drivers reaching xmax way b4 my target spl. I have 4 car subs (83db sensitivity). They play low and nice but require a bolt of lightning to get loud. (way too inefficient). My targets for this project are: +130db spl and any free spl from coupling or floor, minimal woofer damage(I want this rig for a long time) with 8hour continuous play periods, I want powered subs(no wires to trip the wife, she always mistakes them for snakes), 130db spl or more between 27-32Hz.
Subwoofer 4 Ohm. Nominal Diameter 12"
Power Handling (RMS) 250 Watts
Power Handling (max) 500 Watts
Impedance 4 ohms
Frequency Response 23 to 200 Hz
Sensitivity 89.4 dB 1W/1m
Voice Coil Diameter 2.57"
Resonant Frequency (Fs) 23 Hz
DC Resistance (Re) 3.2 ohms
Voice Coil Inductance (Le) 1.94 mH
Mechanical Q (Qms) 5.59
Electromagnetic Q (Qes) 0.44
Total Q (Qts) 0.41
Compliance Equivalent Volume (Vas) 4.12 ft.³
Mechanical Compliance of Suspension
(Cms) 0.33 mm/N
BL Product (BL) 12.31 Tm
Diaphragm Mass Inc. Airload (Mms) 145g
Maximum Linear Excursion (Xmax) 9.3 mm
Surface Area of Cone (Sd) 498.8 cm²
--------------------------------------------------------------Bash 500S Digital Subwoofer Plate
Amplifier 500W RMS
Specifications:
• 500 watts RMS @ 0.5% THD into 4 ohm
load
• Signal to noise ratio: 105 dB (A-
weighted)
• Dimensions: 12" W x 8" H x 3-1/2" D
• Cabinet cutout: 11" x 7"
• Line-in and high-level in crossovers:
Adjustable 50 to 150 Hz, 12 dB/
octave low-pass crossover, a fixed 230
Hz, 12 dB/octave low-pass crossover,
and a fixed 330 Hz, 12 dB/octave low-
pass crossover
• Two stacked LFE-in crossovers: A fixed
230 Hz, 12 dB/octave low-pass
crossover, and a fixed 330 Hz, 12 dB/
octave low-pass crossover
-------------------------------------------------------------- I wanna build 2 cabs: 4 woofers each with a slot port at the bottom tuned between 27-32Hz. Each cab has a Bash 500watt Plate amp powering it. My reason for choosing home woofers is: from my calculations pro woofers only give me 1Watt efficiency from 50Hz up, I wanna avoid power compression, I play lots of music with 30Hz notes, most of my WinIsd/Unibox modeling show drivers reaching xmax way b4 my target spl. I have 4 car subs (83db sensitivity). They play low and nice but require a bolt of lightning to get loud. (way too inefficient). My targets for this project are: +130db spl and any free spl from coupling or floor, minimal woofer damage(I want this rig for a long time) with 8hour continuous play periods, I want powered subs(no wires to trip the wife, she always mistakes them for snakes), 130db spl or more between 27-32Hz.
83 dB sensitivity (one speaker)
86 dB combined sensitivity (two speakers)
89 dB combined sensitivity (four speakers)
92 dB combined sensitivity (four speakers)
92 dB 1 watt
102 dB 10 watts
112 dB 100 watts
122 dB 1000 watts
16 of those drivers with 2000 watts would produce 128 dB, though probably not at 27 Hz.
If you want 130 dB between 27-32Hz you should be considering something serious like Josh Ricci's Gjallerhorn, at 2 meter, ground plane, outdoors it measures:
10hz 90.2db
12.5hz 105.2db
16hz 118.3db
20hz 122db
25hz 124.9db
31.5hz 125.8db
40hz 128.4db
50hz 127.2db
63hz 130.2db
80hz 130.9db
100hz 131.1db
125hz 123.6db
Add 6 dB to those figures for a one meter equivalency, and perhaps another 6 dB for indoor corner loading. Requires more power than any plate amp I know of other than a SpeakerPower unit that requires 240 volts.
Art
And then you closed the post with:
"I have 4 car subs (83db sensitivity)."
At any rate, using only 1000 watts the combined sensitivity of whatever speakers you choose must be 100 dB (at the frequencies of interest) to achieve 130 dB.
Art
Welter Systems, Inc.
8 x Dayton Audio DCS305-4 12" 4ohm 89.4db spl. 100Watts per driver. --------------- Power Handling (RMS) 250 Watts
Power Handling (max) 500 Watts
Impedance 4 ohms
Frequency Response 23 to 200 Hz
Sensitivity 89.4 dB 1W/1m
Voice Coil Diameter 2.57"
Resonant Frequency (Fs) 23 Hz
DC Resistance (Re) 3.2 ohms
Voice Coil Inductance (Le) 1.94 mH
Mechanical Q (Qms) 5.59
Electromagnetic Q (Qes) 0.44
Total Q (Qts) 0.41
Compliance Equivalent Volume (Vas)
4.12 ft.³
Mechanical Compliance of Suspension
(Cms) 0.33 mm/N
BL Product (BL) 12.31 Tm
Diaphragm Mass Inc. Airload (Mms) 145g
Maximum Linear Excursion (Xmax) 9.3
mm
Surface Area of Cone (Sd) 498.8 cm²
Power Handling (max) 500 Watts
Impedance 4 ohms
Frequency Response 23 to 200 Hz
Sensitivity 89.4 dB 1W/1m
Voice Coil Diameter 2.57"
Resonant Frequency (Fs) 23 Hz
DC Resistance (Re) 3.2 ohms
Voice Coil Inductance (Le) 1.94 mH
Mechanical Q (Qms) 5.59
Electromagnetic Q (Qes) 0.44
Total Q (Qts) 0.41
Compliance Equivalent Volume (Vas)
4.12 ft.³
Mechanical Compliance of Suspension
(Cms) 0.33 mm/N
BL Product (BL) 12.31 Tm
Diaphragm Mass Inc. Airload (Mms) 145g
Maximum Linear Excursion (Xmax) 9.3
mm
Surface Area of Cone (Sd) 498.8 cm²
My calculations are like this. 89db. : 1 woofers. 92db. : 2 woofers. 95db. : 3 woofers. 98db. : 4 woofers. 101db: Reflex Cab gain/ Floor gain etc but I'm settling at 100. 120db: 400watts 4 woofers. 126db: 800watts 8 woofers. (According to Forr: db doubling happens when cone area doubles. So after 4 woofers I need an additional 4 more to get +6db gain. - 120db: 1 cab, 4 woofers, 400watts. 126db: 2 cabs, 800watts. 129db: Floor/cab/room gain - These are my calculations. Am I right/wrong and if I'm wrong, how should I calculate woofer/db gain.
You are wrong, each doubling of cone area results in +3 dB, you added in 3 dB for a single driver addition.
It should be:
89 dB : 1 woofers.
92 dB : 2 woofers.
95 dB : 4 woofers.
98 dB : 8 woofers.
Add 30 dB going from 1 watt to 1000, and you are at 128 dB with 8 woofers powered with a total of 1000 watts.
Examples are all through this thread, but your specific details were already answered in #79 and #89.
Codefall
Sound pressure doubles (+6 dB) when the moving air volume doubles,
It is the case when the emitting area is doubled but its excursion unchanged.
Sensitivity specified for 1 W is very confusing.
The sound level of a loudspeaker depends of voltage across the voice-coil,
and the value of this applied voltage is directly accessible to be measured,
not the value of power.
According to the given data introduced in this in line calculator,
mh-audio.nl - Home
the nominal sensitivity of 87 dB for 2.83 V at 1 m.
Never mind, let's keep the data you provided from Dayton.
For 1 W at 1 m
one woofer, 4 Ohm : 89 dB,
a pair of woofers in series, 8 Ohm : 89 dB
two pairs of woofer in parallel, 4 Ohm : 95 dB
For an amplifier of 500 W (45 Vrms in 4 Ohm) at 1 m and one loudspeaker built as you said (each time you double the electrical power, you get 3 dB more SPL) :
1 W : 95 dB
2 W : 98 dB
4 W : 101 dB
8 W : 104 dB
16 W : 107 dB
32 W : 110 dB
64 W : 113 dB
128 W : 116 dB
256 W : 119 dB
512 W : 122 dB
A faster way :
1 W : 95 dB
2 W : 98 dB
4 W : 101 dB
5 W : 102 dB
50 W : 112 dB
500 W : 122 dB
Note that this is theoretical, there are the effets of the room with the proximity of the walls, floor and ceiling which have to be taken in account.
Sound pressure doubles (+6 dB) when the moving air volume doubles,
It is the case when the emitting area is doubled but its excursion unchanged.
Sensitivity specified for 1 W is very confusing.
The sound level of a loudspeaker depends of voltage across the voice-coil,
and the value of this applied voltage is directly accessible to be measured,
not the value of power.
According to the given data introduced in this in line calculator,
mh-audio.nl - Home
the nominal sensitivity of 87 dB for 2.83 V at 1 m.
Never mind, let's keep the data you provided from Dayton.
For 1 W at 1 m
one woofer, 4 Ohm : 89 dB,
a pair of woofers in series, 8 Ohm : 89 dB
two pairs of woofer in parallel, 4 Ohm : 95 dB
For an amplifier of 500 W (45 Vrms in 4 Ohm) at 1 m and one loudspeaker built as you said (each time you double the electrical power, you get 3 dB more SPL) :
1 W : 95 dB
2 W : 98 dB
4 W : 101 dB
8 W : 104 dB
16 W : 107 dB
32 W : 110 dB
64 W : 113 dB
128 W : 116 dB
256 W : 119 dB
512 W : 122 dB
A faster way :
1 W : 95 dB
2 W : 98 dB
4 W : 101 dB
5 W : 102 dB
50 W : 112 dB
500 W : 122 dB
Note that this is theoretical, there are the effets of the room with the proximity of the walls, floor and ceiling which have to be taken in account.
you get a boost over a restricted range of frequencies.
That range of frequencies is determined by the size of the emitting source.
The first part using voltage instead of power is more confusing for me.
The second part using the Power tables is relatively simple.
If a speaker has a sensitivity of 83dB per watt @ 1m in the pass band.
then applying 2W will get you to 86dB @ 1m in the pass band.
If one uses two close coupled speakers of 83dB per watt @ 1m in the passband and share the power between the two speakers so that each receives half a watt, then the pair give 86dB for that 1W @ 1m in the passband.
If you double the power, or double the speakers, you get that 3dB of gain in the passband.
If you double the speakers AND double the power you get 3+3 (=6db) of gain in the passband.
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How do you measure "power" injected to drivers ?
What kind of source are usual amps : voltage or power sources.
Most "powers" when related to loudspeakers and amps are, in fact, voltages converted to powers on a "nominal impedance" of fixed value, and, this impedance, in fact, is essentially variable. This is extremely confusing.
Thinking of voltages is the right way of reasoning.
Forr.....I now understand the coupling theory that u explained. But when it comes to measurement y not use power. All the woofers and amps use power as the noun to describe their load bearing capacity. I think Power = current X voltage(100 watts = 8.33 amps X 12 volts). With 2 woofers in series resistance doubles. My questions are (1) is the current halved since current = voltage / resistance or is the voltage halved. (2) is the voltage split between 2 woofer cones or does it remain constant when connected in series/parallel.