老外的文章，在没有测试设备下设计分频器

dodo1116

http://www.diyaudio.com/forums/m ... ut-measurement.html先收藏一下。哪位高手能翻译过来就最好了

chenqitong

回复 1# dodo1116

你把原文贴上来.

dodo1116

Introduction to designing crossovers without measurement
This tutorial is designed to get you started and tweaking a decent crossover… whether you're new to crossovers, or have built speakers

before and are looking for a design method that relies on listening and doesn't require measurements.

This is a simple but effective crossover. With it you will achieve a much higher quality of crossover than possible using basic online

calculators, and there is enough explanation to enable you to take it to the next level. Math has been kept light.

For illustration, I will be assuming a dome tweeter and a mid sized mid/woofer but with a little common sense this tutorial can apply to

more than just two-way systems using typical drivers.


INDEX

Preparation
Post 2 - Choosing the crossover frequency - Part 1       
Post 3 - Choosing the crossover frequency - Part 2       
Post 4 - Directivity       
Post 5 - Choosing the level       
Post 6 - Baffle step diffraction       
Post 7 - The design process - why the following stages are necessary       

Design
Post 8 - Flattening the woofer's impedance       
Post 9 - Flattening the tweeter's impedance       
Post 10 - The woofer's crossover       
Post 11 - The tweeter's crossover

Tweaking
Post 12 - Phase and diffraction       
Post 13 - Tweaking the woofer
Post 14 - Tweaking the tweeter
Post 15 - Tweaking the system       


You'll need to achieve these goals…
As this tutorial covers more than you may need, here is a list of the essential steps in case you don't plan on reading all of it.

1. Choose a crossover frequency based on your drivers

2. Choose the tweeter level (how loud it should be)

3. Flatten the impedances

4. Add the crossovers

…then on to tweaking. The rest of this tutorial helps in understanding how it works which will make the tweaking process more successful.

The goal of a crossover
Is to blend the sound from the two drivers (woofer and tweeter) so they work together as one. It may need to make the drivers as loud as

each other, to divide the frequencies between them, and to correct or sidestep the limitations each driver will have.

Crossovers will not cut the drivers off suddenly at some frequency. There is a more gradual roll-off, somewhat like rolling a treble or

bass control down. This means the drivers will be working together near the crossover frequency.




CHOOSING THE CROSSOVER FREQUENCY - Part 1
You will firstly need to choose a crossover frequency that gets the best out of the drivers. If we choose too high a frequency, we risk

poor sound from the woofer, and poor matching to the tweeter. If we choose too low a frequency we risk distortion and power handling issues

with the tweeter.

Get some spec sheets
If you haven't already, collect the specifications for each of the drivers which you'll likely find at the manufacturers website. (if not,

read on… but there'll be more on what to do at the end of this section.)

A spec sheet should show a bunch of numbers relating to things such as - how much power it can handle, how big is the cone and how far does

it travel, how loud it plays compared to other speakers etc…

The spec sheet should also show a graph with a couple of lines plotted on it. One line will show how the speaker produces sound by plotting

how loud the speaker will play at each frequency. The other will show how the speaker behaves electrically by plotting how it conducts

electricity at each frequency.

Woofers - choosing where to cross
If you look at the woofer's frequency response plot shown below, you will see that the woofer has a peak in its response at 4kHz (4,000

Hertz) just before it rolls off above 7kHz. In other words, it will play too loud at these frequencies. This peak is not uncommon for a

woofer but it will not always be obvious when looking at some plots.

It is the region of cone breakup, and it is the result of the cone flexing when working at these frequencies. Woofers don't normally sound

good here and it is best to cross them over below this point which prevents them receiving as much energy at these frequencies.

A rule of thumb is to leave at least an octave (or two) between the crossover point and the cone breakup. An 'octave' means a doubling or a

halving in frequency, so in the case of the woofer shown below, our crossover should probably be at or below 2kHz.
Attached Thumbnails
CHOOSING THE CROSSOVER FREQUENCY - Part 2
Tweeters
If you look at the spec sheet for the tweeter below, you'll see one spec named "fs". This is the resonance frequency of the tweeter (550Hz

in this case) and you shouldn't cross this low. The response plot below (image 2) shows that the tweeter can't produce useful sound this

low in frequency although the dome or cone will still move about freely if you ask it to. You can overdrive a tweeter if not careful. This

may produce distortion, or cause damage.

The rule of thumb here is to cross the tweeter an octave above, and preferrably two octaves above the resonance frequency. In our case,

this means our crossover should be higher than 1,100Hz and if possible 2,200Hz.

The best crossover frequency for this example set of drivers
With the woofer's maximum of 2kHz and the tweeter's minimum of 1100Hz, the crossover should be somewhere in this range. I would tend

towards 2kHz as this way, when the volume is turned up the tweeter shouldn't be the first thing to strain (as it probably would if we chose

1100Hz for the crossover frequency). Sometimes a woofer will have particularly bad cone breakup and a tweeter may be known to handle a low

crossover frequency so the option may be there to take yours lower as required.

If you can't get specs…
…then your crossover will be based largely on trial and error (unless you can measure the drivers or find out from someone else) First

you'll need a starting point. If the rated impedance is not written on the driver, you can estimate this by measuring the resistance with a

multimeter (on the speaker terminals) and multiplying this by 1.25 and rounding to the nearest whole number.

When choosing a crossover point, most dome tweeters will happily work down to 5kHz, and some down to 2kHz or less. You should choose a high

crossover frequency to start with as this will reduce the risk of damage. Once you learn the capabilities of the drivers through listening,

you can lower the crossover frequency as this will stop the woofers working at their upper extremes where they may not sound as good.

Generally, smaller woofers can be crossed over at higher frequencies.
Attached Thumbnails
  DIRECTIVITY
Note -- The first time crossover builder may want to skip to the next section…this is here only to make a point about driver selection,

and is slightly technical.

At higher frequencies, a woofer will be producing less sound off to the sides (off-axis). Its forward (on-axis) sound may measure good and

flat across the frequencies we want it to produce, and this may seem to be all that matters.

The attached image shows a plot for a 6" full range driver showing the on-axis response (top line), 30 degrees off-axis (dotted) and 60

degrees off-axis showing the driver is becoming directional at around 2kHz. The total sound (from all angles) reverberates around the room

and comes back to the listening position. The on-axis sound is most important but the total sound is also an issue.

A dome tweeter radiates over a wider angle near the crossover as the dome is smaller. If a crossover was set above a few kHz in this case,

and we based it solely on the on-axis frequency response, there would be less total sound from the woofer just below the crossover. This

could contribute to tonal problems and may cause the tweeter to stand out rather than blending in.

All the same, there are good reasons to use a woofer into this upper region where the design specifically calls for it, usually where a

tweeter with controlled directional qualities is used.

CHOOSING THE LEVEL
This is how loud the speaker will play compared to how much power you give it, and is called it's sensitivity. This is normally how loud

the driver will be if we feed it with one Watt, after screwing it to a large flat baffle and setting the microphone back one metre from it.

As we need to set the tweeter to be around as loud as the woofer, we first need to discover how loud the woofer will be. Our tweeter needs

to already be at least as loud as the woofer because we will be reducing the tweeter's level, not the woofer's.

Discovering the woofer's level
Looking at the woofer specs (image 1), we see that the sensitivity is listed as 87.5 dB/W/m. Looking at the woofer graph you'll see that

much of the plotted response is at that level except for the cone breakup region (image 2).

This will be the level of our example system. If you choose to do some baffle step compensation (next post), this will come down further.

Setting the tweeter level
Later, we will use resistors to make the tweeter more quiet until it matches the woofer level. You should write down the published tweeter

sensitivity specification as well as the chosen system level (in dB).

BAFFLE STEP DIFFRACTION
Note -- The first time crossover designer may want to skip this section as it is slightly technical and is not an essential part of the

basic crossover. It is addressed in the system tweaking section and can be worked on later with little trouble.

What is the problem?
If we were to mount a speaker in the middle of a solid wall, none of the sound would be able to go behind it, but if we mount it on a

narrow baffle some of the sound wraps around the sides and goes off in other directions. The higher frequencies will stay in front, and the

lower ones will wrap around the cabinet. (This is a matter of wavelengths being larger at lower frequencies.) If we were to measure the

response from on-axis, it may seem as if the lower frequencies have gone quiet by up to 6dB (see the attached graph).

The common reaction to this is to use the crossover to cut the woofer's upper response down by 6dB to match the bass as shown in the image.

The problem with this approach is that even though the lower frequencies seem to have disappeared, they haven't. They are still in the

room. If we try to fix the on-axis response we may be creating a new problem of overall balance. Still, baffle step compensation is a

useful tool that may prove useful with some speakers.

It is feasible to do a partial compensation and I would suggest trialling this kind of compensation in small steps.

What to do
If you decide to do any baffle step compensation, you will be lowering only the woofer's higher frequencies. You then need to lower the

tweeter by the same amount.

There are three ways to do this. Firstly, if you use a narrow baffle, your baffle step will happen at a higher frequency nearer to the

crossover. You might simply set your woofer's crossover to a lower frequency (make the inductor larger) which can offset the rising

response.

Secondly, you can use extra components in your crossover, as will be discussed later…

…and thirdly, you can design a speaker that doesn't require compensation, (not something I will cover here), or just leave it for now and

tweak it later after listening tests.


THE DESIGN PROCESS - Why the following stages are necessary
Note -- If you are looking for a 'cookbook' approach, feel free to skip this section. It is a discussion post, and is slightly technical

but recommended. It covers the interactions between the crossover and the speaker, and how to approach the design process. (I will be

ignoring baffle step compensation here as it can be dealt with separately, isn't always necessary, and would needlessly complicate the

following sections).

The first image below shows the example published woofer and tweeter response, with the desired final response. Now, it should be clear

that the woofer and tweeter need to be treated differently… something you wont get following standard formulas.

In order to achieve this target response you'll want to make the individual responses look like the second graph shown below (around the

crossover region). For this no-measurement crossover, I am going to use a first order electrical filter on the woofer and a second order

electrical filter on the tweeter. Although these are not equal, it is more important that the drivers cross well acoustically and this

combination typically works well.

This has the advantage of being a fairly straightforward crossover, whilst offering a fair range of control over the responses, and enough

protection for the tweeter. Even for a 'measured' style crossover, this format is a common final result. I encourage you to think 'outside

the box' once you get the feel for it… for the time being without measurement it may be prudent to start with something like this.

Impedance
This is the final hurdle to cross before we can get down to designing the crossover itself. First though a short explanation of the word

impedance. For our purposes, impedance is the same as resistance except that it applies to alternating current like music signals.

Impedance can be a combination of plain resistance, inductance, and capacitance. The difference being that resistors behave the same at all

frequencies but inductors and capacitors have a varying effect that shows greater influence at higher or lower frequencies.

A crossover is electrical, and when you put one on to a speaker, the impedance plot shows how the speaker will be 'seen' by the crossover.

An example impedance plot is shown as the third image below, and it is fairly typical.

The problem here is that the crossover will have a varying effect as the impedance of the driver varies (i.e: the impedance will present a

lighter or heavier load to the crossover depending on the frequency, which may upset the balance).

How to deal with the impedance issue
Without measurements, we are not as free to design a crossover that works directly around this issue, but this won't be a problem as we can

approach it another way. We will first correct the impedances which then frees us to apply more standard crossovers successfully. This

means flattening the impedance plots near the crossover region, which makes the speakers 'look' more like resistors, which are predictable

and consistent.

FLATTENING THE WOOFER'S IMPEDANCE
We'll need to use one resistor and one capacitor (per woofer). The first image below shows the before and after impedance plot

(grey/yellow). The impedance is now the same at all frequencies around the proposed crossover. The second image shows the schematic

(electrical) diagram so far.

Working out the values
Looking at the specs (image 3) you'll see one called either 're' or 'Rdc'. When working out the value for the resistor in this circuit you

should multiply this value by 1.25. For our example this is 5.5 x 1.25 Although this equals 6.875, there is no easy to find resistor of

this value, but 6.8 ohms will do nicely.

For the capacitor, look for a spec called "Le" which for our example is 0.4mH (that is 0.4 milli, also known as 0.0004). Take your value of

Le and divide it by R squared. For example, our resistor was 6.8 ohms, and 6.8 squared is 46, so 0.0004 divided by 46 gives us a value for

our capacitor of 8.7uF, which is close enough to the easy to find value of 8.2uF.

FLATTENING THE TWEETERS IMPEDANCE
In this section, you need to choose a value to use as the tweeter's impedance in an upcoming section, as well as choosing a resistor to add

to the tweeter circuit.

Adding the resistor
The tweeter has an impedance peak at its resonance like the white curve shown in the first image below, at 550Hz. If we don't take care of

this it may cause the tweeter to play loud around the resonance as our crossover will be less predictable. It may also reduce power

handling.

The simple way to deal with this is to put a resistor in parallel with the tweeter. The entire impedance will be reduced, but the peaks

will be reduced by the greatest amount. The smaller the value of resistor the more effective it will be but don't go too low… you may

lower the total impedance too much which some amps won't like. (It isn't so bad if you plan to add some series resistance later, as will be

shown in the crossover section.)

The first image below shows the effect (from top to bottom) of no resistor, a 20 ohm resistor, and a 10 ohm resistor. This will be a matter

of trial and error for your tweeter. The circuit so far is shown in the second image.

If you are interested in taking this further or have a difficult tweeter, you can look at resonance peak filters. One of these could remove

the peak altogether.

The new impedance
We'll need to know what the impedance is now, in order to work out the values to use later in the crossover. Estimating the 'typical'

impedance value near the crossover frequency will be good enough for our purposes, and is not too difficult.

This example tweeter is a 6 ohm tweeter. Looking at the white curve on the plot below (which is the published curve from the spec sheet),

the impedance goes to around 6 ohms at 2kHz, where our crossover will be. This impedance 'dip' region is not uncommon for the chosen

crossover point because it happens above the resonance where we often choose to cross. For an 8 ohm tweeter we might assume it will be 8

ohms at this point (it isn't really that critical as long as we don't do anything unusual or assume too much).

Because the two blue plots in the image below will not be given on the spec sheets, we need to figure in the effect of the resistance we

put in parallel with the tweeter, and this is how to do it. Start with the rated impedance of the tweeter (such as 8 ohms but in this

example it is 6 ohms). Multiply this by the resistor you put in parallel, then divide this by the amount you get when you add the two. For

example, a 6 ohm tweeter and a 10 ohm parallel resistor…. (6 x 10)/(6 + 10). This equals 3.75 ohms. Write your value down.
THE WOOFER'S CROSSOVER
What we will need here is an inductor. This is a coil of wire that has the property of impeding the flow of high frequency energy whilst

letting the low frequencies pass. The final basic woofer crossover is shown in the image below (…more in the tweaking section).

Choosing the inductor value
Since we have flattened the impedance, we can use the standard formula to find the starting value of inductance. First take the driver's

rated (nominal) impedance and divide this by 6.3 times the crossover frequency. For example, 8 ohms divided by (6.3 x 2000Hz). In other

words, 8/12600 which equals 0.000635 This is also written as 0.635m and the nearest easily available value of inductor should be 0.68mH,

which will make a good starting value.

The second image below shows the frequency response of the woofer with and without the crossover. It isn't quite there yet, but in a later

post on tweaking I will discuss how changing the values of each of the three woofer crossover components gives us a finer control over the

woofers response.

THE TWEETER'S CROSSOVER
There are three components we need to add to the tweeter. A capacitor and an inductor will prevent the low frequency energy below the

crossover from overwhelming the tweeter, and will shape the response near the crossover. A resistor will be used to set the overall level

of the treble. The complete tweeter schematic is shown below.

The capacitor
Take the value of impedance you wrote down two posts ago (for our example it was 3.75). Multiply it by 12.6 and then multiply it by the

crossover frequency. For example, 3.75 x 12.6 x 2000 equals 94500.

Now, if your calculator has an invert function, use it on this number, or simply do 1 divided by your answer. ie: 1/94500 is 10.6uF which

is close enough to 10uF.

The inductor
Take the value of impedance and divide this by the result you get when you multiply the crossover frequency by 3.15

For example, 3.75/(2000 x 3.15) which equals 0.000595, or 0.595m. The closest value of inductor is 0.56mH.

The resistor
If you subtract the woofer sensitivity figure from the tweeter sensitivity figure, you'll have a starting point for how much to lower the

tweeter's level. Lower it a couple of dB more for good measure, if desired (there are several reasons for wanting to try this).

To choose the value of resistor to use, look at the following. To attenuate the tweeter by 1dB, take the tweeter impedance value we've been

using here and multiply it by 0.12 to get the resistor value. For 2dB multiply instead by 0.25, 3dB by 0.4, 4dB by 0.6, 5dB by 0.8, and

finally for 6dB of attenuation use a resistor which is equal to the impedance value.

You'll likely tweak this later, it is a very commonly adjusted component.

Polarity
One final point is the polarity of the tweeter. Try reversing the connections and listen each way. There will be more on why in the next

post.

Finally
The entire response is shown below (image 2). It is a good starting point and will be tweaked later.

PHASE and DIFFRACTION
Note -- This section is slightly technical and may be skipped over if desired.

Phase
A speaker cone moves back and forth in cycles. Each cycle is analysed as a rotation. Phase is an indicator of a point in that rotation, and

is measured in degrees. It is important to consider phase because where you have two drivers sharing the crossover region, they need to

work together. If one is moving out when the other is moving in they will cancel each other to some degree and the direct sound will not be

balanced around the crossover region.

I put this section before the tweaking sections to create awareness as every crossover change you make is going to affect phase to some

extent and to put it simply, this may cause unexpected results in the frequency response. For now, it is enough to just be aware of this

fact.

With regards to the polarity of the tweeter, which is simply the order that the positive and negative wires are connected, both ways should

be tried on each speaker designed this way. As there are only two ways it can be, it is a broad kind of tweak but we need to find which is

best.

As an experimental tweak you can do if there seems to be a problem in blending the tweeter to the woofer, and in keeping with our trial and

error approach… it may be worth changing one of the major components, either the woofer inductor or the tweeter capacitor, then alter the

other driver's crossover to match up. For example, increasing the tweeter's capacitor a little and then increasing the woofer's inductor by

a similar amount will push the crossover lower but shouldn't necessarily change the balance. The point is that the difference in phase

between the drivers may have changed which may have altered how well they blend.

Diffraction
For our purposes, diffraction is when sound encounters a change in direction. For example, if sound is travelling sideways across the

baffle and it reaches the edge, it will expand to reach around the sides. This produces a new (and normally unwanted) wave in return, which

is out of phase and out of time with the original sound.

There is sometimes confusion between this and baffle step diffraction although they are about the same phenomenon. The baffle step shows a

specific and easily measureable effect that gets its share of attention. Diffraction in general tends to be a less easily identifiable

source of problems that should be dealt with by reducing or treating sharp edges where possible.

Diffraction is the reason that drivers are sometimes flush mounted (sunk into the baffle), and why the ratio of baffle height to width and

driver placement on it, is considered. Cabinet edges ought to be rounded as well.

TWEAKING THE WOOFER
There are three components in the woofer crossover. Between them, there is plenty of room for adjustment. Since the resistor and capacitor

are doing a specific job of fixing the impedance, the inductor may seem to be the component that ought be adjusted first, but as we will

see there are no hard and fast rules here.

Fixing our example system
Although we won't see what's going on if we don't measure it, we can still hear it. The top half of image 1 shows the starting crossover,

and it has a small peak at around 1kHz which I will use to illustrate the point. I decided to increase the value of the inductor (to 1mH)

to bring down the woofers response near the crossover.

Adjusting the inductor
Making the inductor larger will reduce the upper midrange by cutting off the woofer at a lower frequency (image 2). This can help to tame

some kinds of harshness, or to give the impression of more bass. It is useful for when the woofer is too loud at its top end to begin with

so if it sounds better, do it. Be aware however that the desire to turn up the bass is sometimes the result of room based cancellations

which have little to do with the crossover.

Going the other way with the inductor can give the bass more punch by increasing the level of bass harmonics. On the other hand if your

tweeter isn't blending, it may be because the woofer is not meeting it at the crossover (not producing enough upper midrange, for example),

so reducing the inductor value might help.

Adjusting the resistor
Reducing this resistance should increase the woofer's output near the crossover without changing the crossover frequency (image 3). This

causes the woofer crossover to more closely resemble a second order filter. In practice, adjusting the resistor gives somewhat similar

effects to the control you get with small changes in the size of the inductor, but there will be differences between the two in response

and phase. With a no-measure type of crossover you should try both if necessary, as one may work better than the other.

Adjusting the capacitor
Also affects the region just below the crossover, and changes the frequency of the crossover. If you found that you had too much upper

midrange but increasing the inductance made the sound too dull, increasing the capacitance value is worth a try instead.

With and without having flattened the impedance
The fourth image below shows the woofer response when using the inductor before fixing the impedance (light blue). Green shows the proper

crossed over response and grey is the raw woofer response for reference. It is obvious that without the resistor and capacitor, the

response is not following the same downward trend. It fails to reduce the cone breakup region sufficiently (above 3kHz).

Notch filters
The fifth image shows the effect of using a notch filter to reduce the breakup region even further. Although I'll leave the design of notch

filters for another time, it can be seen that one is useful in reducing the breakup region by a significant amount. It is usually good to

try to have this region playing 20dB less than the rest of the spectrum. The green trace is the normal crossover and the light blue trace

shows the notch filter in place. It was made using a 0.4mH inductor, a 2uF capacitor and a 3.3 ohm resistor.

Going second order
This will reduce the woofer's output above the crossover where only the tweeter should be heard. If you feel this is necessary, start

reducing the value of resistance in the woofer crossover. This is likely to produce a peak in the response as discussed above and this can

be offset by increasing the inductance. You will have moved closer to a second order electrical crossover.
TWEAKING THE TWEETER
The series resistor
This is the normal method of setting the level and is probably the first thing you'll try when sorting out treble issues. Changes to the

woofer crossover may need an adjustment here as well. Changing this resistor will have the side-effect of bringing about some minor changes

in the tweeter's tonal balance (image 1).

The capacitor
This will change the crossover point for the tweeter. This is a fair tweak if it gives you what you need, even if you don't do anything to

the woofer. Larger capacitors will give you an increase in the response at the tweeter's lower end, and will also increase the level of the

tweeter just above the crossover point (image 2).

The inductor
A larger inductor will also lower the crossover point, but it will reduce the level just above the crossover (image 3).

It may not always be clear whether to adjust the capacitor or the inductor until you try it.

The parallel resistor
Reducing this value will typically reduce the level of the tweeter (image 4). In some cases there will be an emphasis around the resonance,

and top end. In some cases it will produce a better result than adjusting the other resistor, just don't use extremely small values for

this one.

TWEAKING THE SYSTEM
Don't forget to try reversing the tweeter polarity to see which way works best. This should be repeated after significant crossover

adjustments.

Tweeter level
Playing a tweeter louder than it is meant to be played may sound good for a while, but can become tiring. If you find that some recordings

sound a little harsh or bright, and annoying, start by reducing the level of the tweeter. When a tweeter blends, you should only just hear

it, and not specifically…it shouldn't stand out.

General issues
When listening for problems, try to identify which driver is involved (if only one), and which frequency range is involved. Try to repeat

the problem using different types of music. Is it due to some range being too loud or is it some other kind of distortion. Problems due to

some frequency range being too quiet tend to be more difficult to identify. Be persistent, it sometimes takes time to sort out issues like

this.

Not enough bass
Problems around a lack of bass are often due to the room, not the speaker. If you have lowered the midrange and treble with the crossover,

but your bass is still not satisfactory, you might try moving your speakers around and using subwoofers in an attempt to augment the room

affected bass response. It is a commonly held belief that subwoofers are a poor fix for small speakers but subwoofers tend to have a

special case relationship with domestic listening rooms, and are not a bad idea, even overlapping with large speakers.

If you seek more pluck, or punch to the bass lines you'll find this in the midrange, even the upper midrange which is often a matter of

adjusting the woofer inductor or resistor. You might need to correct the tweeter to match.

Dealing with baffle step diffraction
This may be approached by simply increasing the inductance in the woofer circuit until it sounds right. If this lowers the midrange too

much you might lower the resistor value in the woofer circuit. There should be enough control in adjusting the three woofer components in

most cases to bring this issue into line, with some trial and error.

If you are specifically trying to increase the bass a little for whatever reason, you could use a circuit that is usually used for fixing

baffle step issues. Place a second inductor in series with the one already in the woofer circuit, then place a resistor across (in parallel

with) that inductor to limit its effect and prevent it cutting off too much midrange. The resistor should be equal to or less than the

woofers nominal impedance (ie. 8 ohms for an 8 ohm woofer). I'd suggest starting with 4 ohms. Continue to listen for problems and try to

correct what seems to need it. Experiment with the size of the inductor and adjust the tweeter level afterward if required.

A woofer that has been crossed over too high
Two issues here. Apart from cone breakup which has been covered, a woofer that is becoming directional might sound thin in the upper

midrange, which can be worked around by reducing the resistor value in the woofer crossover and/or reducing the tweeter's capacitance

and/or trying different values for the tweeter resistors.

A word on component quality
You may have heard that quality components can make a difference, and this is true to a point. A properly designed crossover using

appropriate off the shelf parts will sound better than a generic crossover using the most expensive parts. You can achieve very good

results using moderately priced components.

dodo1116

我挑重点闲时翻译下

lanfang

好在我使用的是谷歌浏览器马上就给翻译了

dodo1116

8压低低音扬声器的阻抗
我们需要使用一个电阻和一个电容（低音扬声器）。下面的第一张图片显示之前和之后的阻抗图（灰色/）。现在是一样的，在周围所有的频率建议交叉的阻抗。第二个图像显示的原理图（电气）。工作价值观 的规格来看（图3），你会看到一个叫做是're'或'rdc“。你应该在这个电路中工作时的电阻值，这个值乘以1.25。在我们的例子中，这是5.5×1.25，虽然这等于6.875，是不容易的找到这个值的电阻，但，6.8欧姆会做的很好。 电容，寻找一个规范的“le”在我们的例子中是0.4mH （即是0.4毫秒，也被称为0.0004）。勒你的价值和除以它的R平方。例如，我们的电阻为6.8欧姆，6.8平方是46，因此0.0004除以46为我们提供了一个8.7uF，这是足够容易找到价值的8.2uF的电容值。

dodo1116

高音喇叭阻抗变平
在本节中，您需要到选择的值使用的高音喇叭的阻抗在后面的章节，以及选择一个电阻，以增加高音单元电路。增加的电阻 ，高音有一个阻抗峰值在其共振一样的白色曲线示于下面的第一图像，在550Hz显示。如果我们不照顾，它可能会导致高音喇叭大声播放的共振，因为我们的交叉将是难以预料的。它也可能降低功率处理。 处理这个问题最简单的方法是把一个电阻并联的高音喇叭。整个阻抗将减少，但将减少量的最大的峰。电阻值越小，这将是更有效的，但不要太低太多你可能会降低总的阻抗。（这是不是如此糟糕，如果你打算添加一些串联电阻后，将显示在交叉部分）。 下面的第一张图片显示效果（从上到下）无电阻，一个20欧姆的电阻，并一个10欧姆的电阻。这将是一个问题，你的高音喇叭的试验和错误。电路，使显示在第二个影像。 如果您有兴趣进一步采取这种或有困难的高音喇叭，你可以看看共振峰过滤器。其中一个可以完全删除的峰值。新的阻抗， 我们需要知道的阻抗是现在，为了工作的价值，以供日后使用中的交叉。估计'典型'的阻抗值接近交叉频率不够好，我们的目的，是不是太困难。 这个例子高音喇叭是6欧姆高音单元。在下面的情节（这是出版的曲线从规格表）白色曲线，阻抗6欧姆左右在2kHz，我们的交叉。这个阻抗的“探底”地区的情况并不少见，所选择的交叉点，因为它发生上述的共鸣，我们常常会选择交叉。对于一个8欧姆高音单元，我们可能会认为这将是8欧姆，在这一点上（是不是真的那么重要，只要它，因为我们没有做任何不寻常或承担太多）。 由于两个蓝色的地块在下面的图片不能给予的规格表，我们需要弄清楚的阻力的影响，我们将在并联高音喇叭，看看是如何做到的。高音喇叭的额定阻抗（如8欧姆，但在这个例子中，它是6欧姆）的开始。乘你把并联的电阻，然后除以你当你添加两个量。例如，一个6欧姆的高音喇叭和一个10欧姆的并联电阻器.... （6×10）/（6 + 10）。这等于3.75欧姆。写下这个值。

zf45

阻抗补偿，国内书籍都有，但是怎么用呢？怎么用的好的。喇叭音圈电感不好确定，补偿的转折频率要多少合适？楼上这种补偿老实说，效果并不理想。

dodo1116

回复 9# zf45

粗看了下，这都是围绕知道喇叭参数后再做的事。我第一次看到，权当学习吧
还有现在一些大厂的喇叭，基本也有参数可查。看此文过之后就是胡弄分频，也能知道点rcl在网络中的作用。，至少对我有用

yang_aj

收藏一下，慢慢学习。

dodo1116

10.低音的分频点
我们需要的是一个电感。这是一个过滤高音，而让低频通过的导线线圈。下面的图片中显示的最后一个的基本低音单元交叉（在调整部分）。选择电感值， 因为我们已经拉平了阻抗，我们可以使用标准式的电感值。首先，驱动器的额定阻抗（标称值），再除以6.3倍的交叉频率。例如，8欧姆除以（6.3×2000Hz时）。换句话说，这等于0.00063512600分之8也作为0.635米写的，最近的容易获得的电感值应该是0.68mH，这将使一个很好的起点值。 下面第二个图像显示的低音单元的频率响应并没有交叉。这还没完，在上调整以后的文章中，我将讨论如何改变重低音扬声器分频点的三个组件的值给了我们一个更精细的控制的低音扬声器响应。

dodo1116

11高音的分频点
有三个组成部分，我们需要添加的高音喇叭。一个电容器和一个电感器将阻止低频能量低于交叉压倒高音喇叭，将形成的反应接近交叉。将一个电阻，用来设置整体水平的高音。完整的高音喇叭原理图如下图所示。电容器 的阻抗值，你写的前两个职位（在我们的例子中是3.75）。它乘以12.6，再乘以它的交叉频率。例如，3.75×12.6×2000 = 94500。 现在，如果您的计算机具有翻转功能，使用这个数字，或者干脆1除以你的答案。即：九万四千五分之一10.6uF这是足够接近到10uF。电感器 的阻抗值以划分这个结果，你当你乘的交叉频率， 例如3.15 ，3.75 /（2000×3.15），等于0.000595，或0.595米。最接近的值的电感0.56mH 的电阻， 如果你减去的低音扬声器灵敏度数字的高音喇叭灵敏度数字，你就会有一个出发点为多少，以降低高音的水平。降低了几个分贝的好措施，如果需要的话（有几个原因想尝试）。 要选择使用的电阻值，看下面的。衰减了1dB高音喇叭，高音喇叭的阻抗值，我们已经在这里使用，并乘以0.12得到的电阻值。对于2分贝繁殖，而不是0.25，3分贝0.8 0.6 0.44分贝，5分贝的，并最终为6dB的衰减使用一个电阻的阻抗值等于 您可能会调整这个，这是一个非常普遍的调整组件。极性 最后一点是，高音单元的极性。请尝试扭转连接和听各的方式。将会有更多的原因在未来的职位。最后， 整个反应如下所示（图片2）。这是一个很好的起点，以后将进行调整。

dodo1116

相位和衍射
注-这部分是轻微的技术，并如果需要的话，可以跳过。阶段 一种扬声器锥来回移动在循环。每个周期分析作为旋转。阶段是一个指示器中的一个点的转动，以度为单位来测量。重要的是要考虑阶段，因为你有两个驱动器共享的交叉区域，他们需要共同努力。如果一个人移动时，另一种是移动的时候，他们会相互抵消，在一定程度上，直接的声音不会被周围的交叉区域平衡。 我把这个部分，然后再调整部分创建意识，你做的每一个交叉变化在一定程度上影响相，并把它简单，这可能会导致意想不到的结果的频率响应。就目前而言，这是不够的，只是知道这个事实。 的极性的高音，这是一个简单的正，负极电线连接的顺序方面，两种方法应该尝试这种方式设计的每一个扬声器。它可以有两种方式，它是一个广泛的一种调整，但我们需要找到，这是最好的。 作为实验调整可以做，如果有似乎是一个问题，在混合高音单元，中低音单元，并在符合我们的试验和错误的方法，它可能是值得改变的主要成分之一，无论是低音单元电感或高音喇叭电容，然后改变其他驱动程序的交叉匹配。例如，增大的高音的电容一点点，然后增加低音扬声器的电感器由一个类似的量会推低交叉，但不一定要改变平衡。的一点是，驱动程序的不同阶段之间可能会有所改变，可能会改变他们如何融合， 我们的目的。衍射，衍射声音时遇到的变化方向。例如，如果声音正在行驶侧身整个挡板，它达到的边缘，这将扩大到达周围的两侧。这将产生一个新的（而且通常是不需要的）回报，这是波的相位和时间与原来的声音， 有时是混乱这和挡板步骤衍射之间，虽然他们同样的现象。挡板步骤显示了具体和容易衡量的效果，得到它的关注份额。一般衍射往往是一个不太容易识别的源减少或治疗锋利的边缘，在可能的情况下应处理的问题。 衍射的原因是，驱动程序有时齐平安装（陷入挡板），为什么比挡板的高度，宽度和驱动器设置，它被认为是。内阁边缘应该四舍五入。

dodo1116

.调整低音
有三个组成部分中的重低音扬声器分频点。在他们之间，有很大的调整空间。由于电阻和电容做了具体的工作，固定的阻抗，电感器可能似乎应该先调整的组件，但正如我们将看到的是这里并没有硬性的规则。修复我们的例子中， 虽然我们赢了“T看看会发生什么，如果我们无法衡量它，我们仍然可以听到它。1图像的上半部分显示了交叉，在1kHz附近的声音，我将用它来 ​​说明这一点，它有一个小高峰。我决定增加值的电感器（米高）的低音扬声器附近的交叉反应。调整电感， 使大的电感会降低上中端切断低音单元，在较低的频率（图片2）。这可以帮助驯服一些生硬，给人的印象更多的低音。重低音扬声器声音太大时，在它的顶端开始，因此，如果听起来更好，做到这一点是非常有用的。请注意调高低音的愿望，但是有时是有一点点做交叉的会议室取消的结果。 与电感可以去其他方式的低音更有力度通过低音的谐波水平不断提高。另一方面，如果你的高音喇叭不配合，可能是因为低音单元不符合它的交叉（不能产生足够的中频上限，例如），从而减少了电感值可能会有所帮助。调整电阻 减少这种阻力要提高低音单元的输出接近交叉，交叉频率不改变（图3）。这会导致重低音扬声器分频点，使其更接近二阶滤波器。在实践中，调节电阻器给出了有些类似的效果控制，您可以与小的电感器的尺寸变动，但会有响应和相位中的两者之间的差异。使用无措施类型的交叉，你应该都试一下，如果有必要，可能有些人比其他的更好的工作。调节电容 也影响该地区的正下方交叉，并改变频率的交叉。如果你发现你有太多上的中端，但是增加了电感的声音太沉闷，增加电容值是值得一试。并没有扁平的阻抗 时，第四下图显示了低音单元的响应之前使用的电感器固定阻抗（淡蓝色）。绿色显示了正确的回应越过灰色的原始低音响应，以供参考。这是明显的，如果没有电阻器和电容器，响应不遵循相同的下降趋势。它不能减少足够的圆锥体破裂区（3千赫以上）。陷波滤波器 的第五个图像显示效果的使用陷波滤波器，以减少进一步解体区域。虽然我会留下为另一时间的陷波滤波器的设计，它可以看出，一个由一个显着的量是有用的减少解体区域的。它通常是很好的尝试有播放低20dB比的其余部分的频谱的这个区域。绿线是的正常交叉和淡蓝色的跟踪显示的陷波滤波器。它是由使 ​​用0.4mH电感，2UF的电容和一个3.3欧姆的电阻。展望第二阶， 这将减少低音单元的输出只高音单元应该听说过上面的交叉。如果你觉得这是必要的，减少电阻值在重低音扬声器分频点。这是可能的，在响应中产生一个峰值，如上面所讨论的，这可以通过增加电感抵消。您将移动到第二级的电交叉。

dodo1116

14.调整高音
串联电阻
设定水平，这是正常的方法，可能是你首先会尝试进行排序时，高音的问题。的重低音扬声器分频点的更改可能需要调整。改变这个电阻会产生的副作用带来的一些细微变化的高音喇叭的音调平衡（图片1）。电容器， 这将改变交叉点的高音喇叭。这是一个公平的调整，如果它给你你所需要的，即使你什么也不做的低音扬声器。更大的电容会给你增加高音的低结束的响应，并会同时增加的高音喇叭的交叉点（图片2）的正上方水平。电感器 一个较大的电感会也降低了交叉点，但会水平降低的正上方交叉（图3）。 也许并不总是明确是否调整电容或电感，直到你试试吧。并联电阻 减小该值通常会减少的高音水平（图4）。在某些情况下，会有一个强调周围的共振，并且上端。在某些情况下，它会产生更好的结果比其他电阻调整的，只是不使用这一个极小值。

chenqc1626

看了,就一个字"晕",我才疏学浅没办法

slquan

直搬谷歌的翻译而不作语法和词意的调整~~~~~~

伯乐快马

记号，顶老外。