Get him a DH-500. Then he can do his weightlifting at the same time.
Mine is currently holding down a workbench in my anti-gravity lab.
Mine is currently holding down a workbench in my anti-gravity lab.
Ahh the unrealistic boomy bass speaker ideas I get,lol. Ok to the point.
If you have a speaker with a sensitivity of 93 db and place it right beside the same speaker you'd have a sensitivity oif 96 db? So say you were to place 4 drivers (like pictured) as close to each other as possible where each driver will have two identical drivers placed on two of it's sides would the sensitivity rule still Carry out as normal which I think would give you a sensitivity gain of 12 db giving you a sensitivity of 105 db. Is that the sensitivity you'd get from the driver placement? I'm curious as to what it would be and if I'm wrong what would the sensitivity be?
If you have a speaker with a sensitivity of 93 db and place it right beside the same speaker you'd have a sensitivity oif 96 db? So say you were to place 4 drivers (like pictured) as close to each other as possible where each driver will have two identical drivers placed on two of it's sides would the sensitivity rule still Carry out as normal which I think would give you a sensitivity gain of 12 db giving you a sensitivity of 105 db. Is that the sensitivity you'd get from the driver placement? I'm curious as to what it would be and if I'm wrong what would the sensitivity be?
Attachments
You are likely to get lots of different answers to this one but I remember that everytime you double the drivers, you add 3 dB. So 2 = +3dB. and 4 = + 6dB. But I think in the real world that translates to about 5 dB.
I don't think they have to be right next to each other for +3dB
I think Cal's right - you add 3dB every time you double the number of drivers. Each 3dB is double the volume, so it makes sense that twice as many speakers would double the volume, But your ears only hear it as somewhat louder, that's just how ears are... , so that's why they use dB to measure it - a logrithmic scale. I believe 10 dB SOUNDS twice as loud.
Now if you wire up 2 8 ohm drivers in parallel , then their combined load on the amp is 4 ohms instead of 8. That may give you significantly more power, maybe doubling the dB again, IF your amp can handle it. I believe most pro amps CAN handle 4 ohms loading. BUT going down to 2 ohms will blow many amps.
So its possible that two drivers hooked in parallel will be more
like +6dB
If you hook up 4 8ohm drivers to one amp the total will be 2 ohms or 8 ohms depending on how its wired
Starting with efficient drivers is the way to go!
As Cal said, there are various opinions about this stuff so we'll probably get some more input!
I think Cal's right - you add 3dB every time you double the number of drivers. Each 3dB is double the volume, so it makes sense that twice as many speakers would double the volume, But your ears only hear it as somewhat louder, that's just how ears are... , so that's why they use dB to measure it - a logrithmic scale. I believe 10 dB SOUNDS twice as loud.
Now if you wire up 2 8 ohm drivers in parallel , then their combined load on the amp is 4 ohms instead of 8. That may give you significantly more power, maybe doubling the dB again, IF your amp can handle it. I believe most pro amps CAN handle 4 ohms loading. BUT going down to 2 ohms will blow many amps.
So its possible that two drivers hooked in parallel will be more
like +6dB
If you hook up 4 8ohm drivers to one amp the total will be 2 ohms or 8 ohms depending on how its wired
Starting with efficient drivers is the way to go!
As Cal said, there are various opinions about this stuff so we'll probably get some more input!
yeh, I know the best way to go is efficeient drivers but I was just curious about this because I've seen at some car SPL comp they'll place each driver right beside aqnothe kinda like in the pic only it'll be more like 12-14 drivers like that.
Perhaps it's even simpler than this, in that if you have two drivers beside each other at the same SPL, the on axis SPL is simply up by 6dB.
I cite the second order Linkwitz-Riley crossover with 6dB of attenuation at the crossover point, phase coherence between the drivers and a flat on axis combined SPL. A text book first order crossover is 3dB down at the crossover point but only achieves the flat on axis SPL by way of the phase difference between the drivers, otherwise there would be a 3dB peak.
At least at those frequencies.
Hi,
BUT
there is a condition.
The distance across the speakers must not exceed about half to a quarter of the wavelength of the highest frequency that the speaker reproduces. Suppose the speaker goes upto 100Hz then one wavelength=3.4m and wl/4=0.85m then that is the maximum spacing across the drivers to achieve the full benefit from the +6db for each doubling of drivers and power.
I have not seen a definitive description of how one measures the limiting distance across the drivers. I do not think it is the centre to centre distance of the farthest apart drivers.
that's confirming you have doubled the power into the pair of speakers. This cannot be achieved by wiring the two drivers in parallel. You need two amplifiers each driving their own speaker.
confirms that if you double the power and double the number of speakers you gain +6db SPL (four times the output power=twice the sensitivity).
BUT
there is a condition.
The distance across the speakers must not exceed about half to a quarter of the wavelength of the highest frequency that the speaker reproduces. Suppose the speaker goes upto 100Hz then one wavelength=3.4m and wl/4=0.85m then that is the maximum spacing across the drivers to achieve the full benefit from the +6db for each doubling of drivers and power.
I have not seen a definitive description of how one measures the limiting distance across the drivers. I do not think it is the centre to centre distance of the farthest apart drivers.
Punkr,
These discussions tend to run on. It is a little complicated in fact.
You'd think we would have and answer- sorry to disappoint you 😉
Andrew, if the speakers are wired in parallel, then the impedence is halved, and you are getting double the power, no? (if the amp is capable of doubling its output into 4 ohms, which many solid state designs can I think.- that's why they are rated at different outputs into different impedences.)
These discussions tend to run on. It is a little complicated in fact.
You'd think we would have and answer- sorry to disappoint you 😉
Andrew, if the speakers are wired in parallel, then the impedence is halved, and you are getting double the power, no? (if the amp is capable of doubling its output into 4 ohms, which many solid state designs can I think.- that's why they are rated at different outputs into different impedences.)
I thought we were discussing the sensitivity of the speakers not making an allowance for the extra power now available from the amp due to a change in impedance.
We do have an answer. You get a potential 6 dB increase from 4 drivers versus 1 at the same input power. Never mind the amp for now. We never run them at full power (or shouldn't) so I don't see the significance.
For some reason(s) you never get the expected increase so that's why I guessed at 5dB in the real world.
We do have an answer. You get a potential 6 dB increase from 4 drivers versus 1 at the same input power. Never mind the amp for now. We never run them at full power (or shouldn't) so I don't see the significance.
For some reason(s) you never get the expected increase so that's why I guessed at 5dB in the real world.
This must be a confusing topic, because the debate seems to go on and on. And we don't always hear the same thing. 😉
I'll admit that it confuses me, too. But how I understand it this:
Let us keep the amplifier voltage the same for all these examples. Don't touch that dial! And we will set our voltage at our favorite 2.83 volts. 1 watt into 8 ohms. We are going to stay at 2.83 volts, no matter what.*
We have an 8 ohm driver that will give us 95 dB at our 2.83 volts. (1 watt)
Add a second driver and it is said that we get a 3 dB gain in efficiency. But we can't just "add another driver" we have to connect it. How? In series or in parallel.
When we connect the 2nd driver in series, we get a 3 dB efficiency gain by adding the extra cone and motor. But... we now have a 16 Ohm load, so only 1/2 as much current flows, so 1/2 the power. We lose 3 dB. So no net gain as long as voltage remains the same. We would need to go to 4 volts to get back to 1 watt, and find the 3 dB gain.
When we connect the 2nd driver in parallel, there is now a 4 ohm load. So we gain 3 dB efficiency by adding the 2nd cone/motor - and - we pick up 3 dB because twice as much current flows. Net SPL gain - +6 dB. But we are now using twice as much power as before - 2 watts.
But wait a minute. Why do we get 3 dB more? The total load is now 4 ohms, sure, but each driver is still 8 ohms, so it is still putting out 95 dB because it is still pulling the same amount of current, thus the same power - 1 watt each. The drivers don't know that there is another driver connected. They are still dissipating 1 watt each, producing 95 dB. So shouldn't the gain be just 3 dB?
Well, yes. Except that the 2 drivers can be seen as a system. The system is now 3 dB more efficient than it was with a single driver. So it will give us 98 dB/watt. And the system is now dissipating 2 watts because the voltage stayed the same. So 3 more dB. We now have 101 dB at our 2.83 volts.
But this voltage is now producing 2 watts.
When we connected the 2 drivers in series, the system efficiency increased by 3 dB, but the power was cut in half because of the series wiring. No increase in SPL at the same voltage.
* The reason this example keeps the amplifier voltage constant is because that is what tends to happen in the real world. We talk about watts, but it might be better to talk about volts. As long as you don't change the volume (gain) the amp will supply the same voltage into a wide range of loads. You can see how changing the load will cause more or less current to flow, thus more power will be used.
And as Cal has noted, you usually don't get the full 3 dB, for various practical reasons.
(corrections welcome!)
I'll admit that it confuses me, too. But how I understand it this:
Let us keep the amplifier voltage the same for all these examples. Don't touch that dial! And we will set our voltage at our favorite 2.83 volts. 1 watt into 8 ohms. We are going to stay at 2.83 volts, no matter what.*
We have an 8 ohm driver that will give us 95 dB at our 2.83 volts. (1 watt)
Add a second driver and it is said that we get a 3 dB gain in efficiency. But we can't just "add another driver" we have to connect it. How? In series or in parallel.
When we connect the 2nd driver in series, we get a 3 dB efficiency gain by adding the extra cone and motor. But... we now have a 16 Ohm load, so only 1/2 as much current flows, so 1/2 the power. We lose 3 dB. So no net gain as long as voltage remains the same. We would need to go to 4 volts to get back to 1 watt, and find the 3 dB gain.
When we connect the 2nd driver in parallel, there is now a 4 ohm load. So we gain 3 dB efficiency by adding the 2nd cone/motor - and - we pick up 3 dB because twice as much current flows. Net SPL gain - +6 dB. But we are now using twice as much power as before - 2 watts.
But wait a minute. Why do we get 3 dB more? The total load is now 4 ohms, sure, but each driver is still 8 ohms, so it is still putting out 95 dB because it is still pulling the same amount of current, thus the same power - 1 watt each. The drivers don't know that there is another driver connected. They are still dissipating 1 watt each, producing 95 dB. So shouldn't the gain be just 3 dB?
Well, yes. Except that the 2 drivers can be seen as a system. The system is now 3 dB more efficient than it was with a single driver. So it will give us 98 dB/watt. And the system is now dissipating 2 watts because the voltage stayed the same. So 3 more dB. We now have 101 dB at our 2.83 volts.
But this voltage is now producing 2 watts.
When we connected the 2 drivers in series, the system efficiency increased by 3 dB, but the power was cut in half because of the series wiring. No increase in SPL at the same voltage.
* The reason this example keeps the amplifier voltage constant is because that is what tends to happen in the real world. We talk about watts, but it might be better to talk about volts. As long as you don't change the volume (gain) the amp will supply the same voltage into a wide range of loads. You can see how changing the load will cause more or less current to flow, thus more power will be used.
And as Cal has noted, you usually don't get the full 3 dB, for various practical reasons.
(corrections welcome!)
oik well everyone kinda jumping around on this mainly because they don't know what I intend for and amp.
For arguments sake let's say I'm using 4 speakers with a sensitivity of 93db. They are beside each other like I originally pictured.
The speakers are powered by 2 equal amps. An amp for the bottom pair and an amp for the top pair.
Each pair of 8ohm speakers are wired in parallel to give an impedance of 4ohm.
right?
Sp let's say each is putting out 1 watt/2.83 volts @ 8 ohm which translates to each speaker getting 1 watt. to each speaker right?
So saying that's the case what would the sensitivity of all the speakers total be?
BTW for the record when I'm talking about amps and speakers I'm referring to the econo $60 MJ-18 18" subwoofer and the Europower 2500 amps. But let's not focus on that. I've set up a pretty much very optimistic setup (^) so what would my results be?
For arguments sake let's say I'm using 4 speakers with a sensitivity of 93db. They are beside each other like I originally pictured.
The speakers are powered by 2 equal amps. An amp for the bottom pair and an amp for the top pair.
Each pair of 8ohm speakers are wired in parallel to give an impedance of 4ohm.
right?
Sp let's say each is putting out 1 watt/2.83 volts @ 8 ohm which translates to each speaker getting 1 watt. to each speaker right?
So saying that's the case what would the sensitivity of all the speakers total be?
BTW for the record when I'm talking about amps and speakers I'm referring to the econo $60 MJ-18 18" subwoofer and the Europower 2500 amps. But let's not focus on that. I've set up a pretty much very optimistic setup (^) so what would my results be?
Attachments
If you are starting out with a 93dB/watt driver, then with 4 hooked up the way you want, you be getting about ~102dB with 4 watts. That's 2 watts from one amp, 2 from the other.
That's only 3dB more than you'd get running 4 watts (higher voltage) into a single driver, but all that cone surface will probably have more impact, and 4 drivers will handle a lot more power, when you really get it cranking.
You'd do well to use one amp for one side, another amp for the other side. Put the amps right behind the speakers. Using one amp per set of 4 drivers will give you a lot more punch than a single amp for both sides.
It will get crazy loud, no worries. 8x18 is a big PA rig, don't fool yourself.
That's only 3dB more than you'd get running 4 watts (higher voltage) into a single driver, but all that cone surface will probably have more impact, and 4 drivers will handle a lot more power, when you really get it cranking.
You'd do well to use one amp for one side, another amp for the other side. Put the amps right behind the speakers. Using one amp per set of 4 drivers will give you a lot more punch than a single amp for both sides.
It will get crazy loud, no worries. 8x18 is a big PA rig, don't fool yourself.
Well...Er...Precision Devices 18s...Er... Just a tad more expensive...🙂
edit: Still, it wasn't as nice as two dual 15" Renkus Heinz boxes on top of a Turbosound horn with a single PD 2450 per side.
edit: Still, it wasn't as nice as two dual 15" Renkus Heinz boxes on top of a Turbosound horn with a single PD 2450 per side.
TAD is always more expensive. 😉
Don't know if Mr. P is planning 4x18s total or 4x18s per side.
But with those $60 drivers, at least they won't be too stressed. Might be a good idea. Can move lots of air without taxing the cheap drivers too much.
If he just wants a Wall O' Bass, then 4 in the middle like his drawing could be cool. Then he could put his 12" "satellites" on left and right.
Don't know if Mr. P is planning 4x18s total or 4x18s per side.
But with those $60 drivers, at least they won't be too stressed. Might be a good idea. Can move lots of air without taxing the cheap drivers too much.
If he just wants a Wall O' Bass, then 4 in the middle like his drawing could be cool. Then he could put his 12" "satellites" on left and right.
, i know people here have heard of it, hehe I'm thinking of goin from 18/12 to 24/12, any comments?
so just so you know when I say I want the serious stuff I mean I want drivers like the 24" beast called a pd2450, if someone has a problem with the pd2450 or thinks they know of a bigger badass than the pd2450 please do let me know and bring it to the table cause a 60lb 24" speaker doesn't seemto have much competiton from what I've seen.
How about this 31.5" woofer from Fostex?
FW800N
I honestly don't know of a larger diameter woofer that a consumer can purchase. Is that what you meant by competition?
Your Precision Devices driver didn't list an Xmax, but if I figured it correctly (voicecoil winding depth minus magnet gap depth), then you'd see about 4.3 liters of displacement from this driver. The fostex has about 3 liters of displacement, but it's bigger.
On the other hand, for the cost of that Fostex driver you could get ten Soundsplinter RL-P 15". They would have about 28 liters of displacement.
For just a little more, you could get a rotary subwoofer that plays down to zero hertz.
Sorry, but for me this thread lost it's point a long time ago. I'm glad you got the other thread about the BIB- that actually looks like it could make some loud noise for you within a reasonable budget and sound OK doing it. How's that going?
FW800N
I honestly don't know of a larger diameter woofer that a consumer can purchase. Is that what you meant by competition?
Your Precision Devices driver didn't list an Xmax, but if I figured it correctly (voicecoil winding depth minus magnet gap depth), then you'd see about 4.3 liters of displacement from this driver. The fostex has about 3 liters of displacement, but it's bigger.
On the other hand, for the cost of that Fostex driver you could get ten Soundsplinter RL-P 15". They would have about 28 liters of displacement.
For just a little more, you could get a rotary subwoofer that plays down to zero hertz.
Sorry, but for me this thread lost it's point a long time ago. I'm glad you got the other thread about the BIB- that actually looks like it could make some loud noise for you within a reasonable budget and sound OK doing it. How's that going?
- Status
- Not open for further replies.