Hi, just a quick one.
I'm trying to understand baffle step correction a little better.
As far as I understand basicaly there is a reduction in sound energy at the listening position due to sound being radiated like a point source (like a lightbulb) at low frequencies, but then becomming directional at higher frequencies (like a car's headlamps), and the cutoff point is determined/influenced? by the baffle...
I hope I got it right so far to some extent.
Now my question relates to useing all the oline calculators etc. and comprehending the source papers most quote.... They refer to the width of the baffle. Is this litleraly the width, i.e. from left to right side, or just the longest dimensions? If not just the longest dimension, why is that not incorporated into the calculations also?
Then a second unplaned question that just occured to me.
In a multi-way system, is there any benefit in designing a a box with dimensions that creates the step at frequencies that are the same as the crossover network's switching points.
I'm trying to understand baffle step correction a little better.
As far as I understand basicaly there is a reduction in sound energy at the listening position due to sound being radiated like a point source (like a lightbulb) at low frequencies, but then becomming directional at higher frequencies (like a car's headlamps), and the cutoff point is determined/influenced? by the baffle...
I hope I got it right so far to some extent.
Now my question relates to useing all the oline calculators etc. and comprehending the source papers most quote.... They refer to the width of the baffle. Is this litleraly the width, i.e. from left to right side, or just the longest dimensions? If not just the longest dimension, why is that not incorporated into the calculations also?
Then a second unplaned question that just occured to me.
In a multi-way system, is there any benefit in designing a a box with dimensions that creates the step at frequencies that are the same as the crossover network's switching points.
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I think that it has to be related to what the loudspeakers are supposed to do , i.e. create a sound stage which may have 3D connotations ,like (other than the distance between the speakers ) depth and height .
me too ...reading here on the forum about the subject from enlightened minds makes me immediately comprehend the argument ,then ...next day is total dark !!Well ,it is scientifically true everything that has been written on BSC ...
For me it's just the lowpass of a woofer giving a certain Q ....
It's about baffle width and the space where the speaker is working. To calculate the F3 at the baffle step use 115/baffle width in metres.
I'll give you a visual example of baffle step using ants.
With a speaker against the wall (2PI space), picture the baffle covered in ants. As some ants escape to the back of the speaker they can't hide so you see them all (no baffle step reduction).
With a speaker in free space (4PI space), the escaped ants now can hide behind the box so you can't see them, only the remainder. That's the SPL reduction from baffle step.
I'll give you a visual example of baffle step using ants.
With a speaker against the wall (2PI space), picture the baffle covered in ants. As some ants escape to the back of the speaker they can't hide so you see them all (no baffle step reduction).
With a speaker in free space (4PI space), the escaped ants now can hide behind the box so you can't see them, only the remainder. That's the SPL reduction from baffle step.
That's generally used in 3-way designs. You address the baffle step issue by crossing over to a higher SPL woofer at around the baffle step F3. This provides the necessary BSC without needing additional crossover components.
An example is an enclosure 350mm wide, so the woofer would crossover at around 328Hz to help with BSC. The mids etc do not need correction as are operating far above the baffle step.
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Not exactly. There is still the same amount of energy being radiated, it is just being spread at a wider angle at lower frequencies. To say that it will not be heard at the listening position is a little naive (for want of a better word
), especially at the lowest frequencies where it matters little where the sound went, only how much there is.Rather than use those, you might play around with a baffle diffraction simulator app or spreadsheet. These won't indicate the total sound put out into the room but only the direct sound to the listening position from the baffle, including edge diffraction which causes ripples higher up. I think this will teach you visually what is happening.
Thanks for your time so far.
Ok so lets say I have the following, a driver in box 332mm from left to right.
It as an Re of 7.4R and is rated at 86db/W
According to the calculator the components I need for the correction is a147k resistor and a 65mH inductor. I assume it needs to be able to handle the current from the amplifier, lets say it can supply 4A, thats a GIANORMOUS inductor, certainly not in digikey catalogs etc.... am I doing something wrong?
Ok so lets say I have the following, a driver in box 332mm from left to right.
It as an Re of 7.4R and is rated at 86db/W
According to the calculator the components I need for the correction is a147k resistor and a 65mH inductor. I assume it needs to be able to handle the current from the amplifier, lets say it can supply 4A, thats a GIANORMOUS inductor, certainly not in digikey catalogs etc.... am I doing something wrong?
I'm gonna make this a seperate post as I'm not sure to what extent these are linked yet. If the driver is 226mm wide (outer edge of frame) and you had a microscopicaly small tweeter (for the sake of the experiment), placed right on this border. The shortest wavelenght that could span from center to center would be just over 1500Hz. Does this mean that to approximate a point source, the highest frequency the woofer should cross at( Or possibly the correct frequency) would have to be under 1500, (under becasue as the tweeter size grows the frequency would drop a little). Which would correspond with the corner frequency of a baffle width of 22.9cm. (lol, thats less than the width of the driver, I think my brain just had a phase inversion...)
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Hi,
I think, you are...Are you designing a passive or active compensation?
b
Touche, yes, this would be doable at line level and I do intend to play with active. I have a bunch of drivers, tweeters and boxes, none properly optomised for each other, I am trying to identify which things will complement each other best if optimised properly... but that is beside the scope of my inquest, I'm simply trying to understand the very basic fundementals (lacking any calculus schooling, we only had algebra and trigonomentry and that was decades ago), to help me make informed choices and starting points for experiments.
No, The system would not approximate a point source but Lambda/4 would, ie at ~380 Hz.
I really don't not what you are after...To use the 'Edge correctly you need to specify the baffle size, driver sizes involved and the supposed listening height above the floor. Prior to this I suggest you use the Xdir program to make a decision on where you want to put your summed FR loobes, i.e. by choosing the acoustic XO, whether a odd or even order is to be picked...
You don't need more...as this subject is very basic..b
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Good article. BSC equals bass boost equalization to speakers with small baffles placed away from a wall that would otherwise reinforce bass acoustically. The article points out the advantages of providing this boost by active equalization before the power amplifier, the disadvantages of providing it passively with an inductor after the power amplifier, and why that is the way it is commonly done anyway because of the nuttiness of the way audiophiles view the world. It's certainly one way to increase cost.
Soundminded ,I don't follow you . Are you suggesting to put a 'black box' before the amplifier to give the correction to a precise loudspeaker ?
I remember I saw those things (Myst ) in the digital world many years ago ,and you did have to put on a EEPROM the correction curve for that kind of loudspeaker system . I don't see any around ,now .
A simple meter of copper ( or more)is simple ,elegant ,unique !!
I remember I saw those things (Myst ) in the digital world many years ago ,and you did have to put on a EEPROM the correction curve for that kind of loudspeaker system . I don't see any around ,now .
A simple meter of copper ( or more
)is simple ,elegant ,unique !!
No, there is no benefit...regardless, even, of how many drivers and where their crossover points are. There will still be a transition from full space radiation to half space radiation at the baffle imposed step frequency.
Soundminded ,I don't follow you . Are you suggesting to put a 'black box' before the amplifier to give the correction to a precise loudspeaker ?
I remember I saw those things (Myst ) in the digital world many years ago ,and you did have to put on a EEPROM the correction curve for that kind of loudspeaker system . I don't see any around ,now .
A simple meter of copper ( or more
The referenced article makes it clear. The FR is designed depending on where the speaker is anticipated to be placed compared to adjacent walls and other reflecting surfaces including the driver's own baffleboard. With no acoustic reinforcement from a narrow front baffleboard or nearby walls the bass output relative to the rest of the spectrum is reduced especially when the speaker is pulled away from the back wall. This will make the speaker sound bass shy unless bass output is increased in one of two ways. Either boost the bass input signal to the power amplifier stage or cut down on the output above the bass after the power amplifier in the crossover network with power wasting passive devices for the rest of the spectrum. But since audiophiles reject the use of active equalizers to boost bass, the second far less efficient and less controllable method is invariably preferred by them. This also opened up a market for a whole new class of devices that was never seen before the last decade or two, the outboard subwoofer as a supplement for what are touted to be full range high quality speaker systems.
Sorry Digits -I hope you dig it - but I have another question to Soundminded , that I thought it was implicit with my previous sentence.
So you think that a non..audiophile would need the 'black box' ,then rotate some knobs to fit them to their like ....
I've got the answer !!! Google Traduttore
which doesn't relate to BSC ,of course
The problems are the audiophiles and their wives !!!
- but I have another question to Soundminded , that I thought it was implicit with my previous sentence.So you think that a non..audiophile would need the 'black box' ,then rotate some knobs to fit them to their like ....
I've got the answer !!! Google Traduttore
which doesn't relate to BSC ,of course
The problems are the audiophiles and their wives !!!
Above the schroeder frequency, adjacent surfaces some distance away will contribute a series of peaks and cancellations rather than a certain level of overall reinforcement.
Trying to specifically boost a cancelled part of the spectrum would be futile and is ill-advised.
Floyd Toole has written extensively on bass response and how to achieve uniformity. That IMO is his one major contribution to audio knowledge. Where does he recommend locating LF speakers and how many?
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