Japanese Version @@@@Ver.1.12 Rev. 2014/05/21

Speaker Network Design
Welcome to Speaker Network Design RoomI

Excel Design Sheet for Speaker Network is publised.


Number of speakers is 2-4way, circuit type of network is 6-24dB/oct. Data in this design sheets are the
pure theory value that I made by the calculation of the electric circuits, and not the experimental value.
Windows‚V+Excel 2010,WindowsXp/Me+Excel 2000 were used in a development stage, with no trouble.

Design Sheet for 2way@@ Design Sheet for 3way@@ Design Sheet for 4way

Applied example 1@@ Applied example 2

Guidance of Speaker Network Circuit

Knowledge of Speaker Network Patrs

Circuit Diagram of 2way Speaker Network

Circuit Diagram of 3way Speaker Network

Circuit Diagram of 4way Speaker Network

Calculation Sheet for Speaker Network Parts

If you want to obtain above files, please download compressed files followed, and melt them in the same folder.
Download File 1/4@@ Download File 2/4@@ Download File 3/4@@ Download File 4/4

(The design of the speaker network circuit from an electric circuit theoretic point of view)
The speaker network circuit is the constitution that is very simple for an electric circuit, but the influence to
give the quality of the speaker system is big. And there are some points that I feel not a little doubt in the
present conditions of the speaker system, which include current design thought and which is made by famous
manufacturer also. It may be thought too particular about trifles, and it seems to be one of few fields left
behind in the modern advanced electric industry by an electric theory. It is the one of these causes to feel doubt in
calculating the impedance of the speaker as pure resistance, and to downplay a theory. As for another one, the sound
is often in some situation so that a theory is ignored because prominent expertise of the listening is given priority and
is considered to be the field of the art. However, when you lost the judgement of a theoretical route, you should not
have given priority to a theory in all situation, there can be that solving by auditory capability is a shortcut. However,
I do not need to say daringly, and the electric circuit theory is a tool that it seems to be like the car navigation system
which guides to the neighborhood of the destination for the field of the audio system, and it is not the thing which
should never make light of it. I compiled the main point about the design of the speaker network which I felt from
the electric theoretical standpoint. The contents of this sentence extracted the purpose of the attached document.
1. Alternating current resistance, not direct current resistance is to be used for calculation of speaker network.
The impedance of the speaker is mentioned in a catalogue so that the maker says 4ƒΆ or 8ƒΆ as nominal impedance.
If the impedance of the speaker is not pure resistance in calculating formula, a calculation of impedance becomes
complicated, and a calculation becomes difficult, and the network circuit in a speaker system is not desirable because
the unevenness of the frequency characteristic grows big. Therefore, the reproduction range must be chosen
without contradiction as a frequency range in which the impedance is similar with pure resistance. But this is a
case of the multi-way speaker and it is used without minding even if impedance is disturbed in the case of the full-range
speaker if an output response is good. Pure resistance to say here is not direct current resistance by alternating
current resistance. It is a too unconcerned story that the alternating current resistance substitutes by the direct
current resistance because alternating current resistance are 10-30% big values than direct current resistance.
Emission resistance (while it is installed in a speaker box), eddy current loss are included in alternating current
resistance other than direct current resistance. Because it is a formula that (impedance = alternating current
resistance + reactance composed by LC), in the case that reactance composed by LC equal to zero, the alternating
current resistance and the impedance become equal. Therefore, you may regard minimum impedance (nominal
impedance) as alternating current resistance. Such a virtual alternating current resistance is called effective resistance.
2. Total output voltage is important at the low frequency, and the output power is important at the high frequency.
A full-range speaker has no responsive difference between the voltage and the power, but in the case of a multiway
speaker, a phase change occurs to the voltage of each speaker, and a difference between response of electric
power and response of the total voltage may occur. Because a wavelength is long in the case of the low tone, a phase
difference caused by the position in the sound field becomes small. Therefore, it is important that a total output voltage-
frequency curve is flat through low frequency band so that it is thought that the total voltage is in proportion to sound
pressure. Because a wavelength is short in the case of the high tone, a phase difference caused by the position in the
sound field becomes big. In the case of total output voltage-frequency curve being flat, it is only an angle on the axis of
the speakers that sound pressure-frequency curve becomes flat, and if the angle is different, a phase difference will
change, and sound pressure will change. Therefore, the output level of the sound field will depend on output power.
You need not to do the useless effort that you move the installation of the tweeter 1cm to match the phase.
It is surely desirable for both the total voltage curve and the electric power curve against the frequency to be flat, for the
output response of the network.
3. It is important that the input impedance of the network circuit must be equal to speaker resistance.
The output voltage of the audio amplifier is constant voltage regardless of frequency when input is given constant voltage.
Generally it is called constant voltage source. This is a digression, and in case of constant current source, internal
resistance is nearly infinite, because dumping of speaker is very bad, sound quality of constant current source is not good.
The constant output power is produced when constant resistance is connected to the constant voltage source.
When the input impedance of the network changes by frequency, both the output power and the input electric current
change, and the output power curve for the frequency is not flat.
4. Both the phase distortion and cost of parts increase when the crossover of the network is set to low frequency.
The fixed number of the network parts becomes big when crossover frequency is taken low. When they make the part
fixed number big, a cost rises, a phase change becomes big, and phase distortion increase. Therefore, it is not good to
lower the crossover frequency of the network more than required.
5. The coil without core is good for speaker networks.
The coil with iron core make reducing size and lowering the direct current resistance, but is not good for sound quality
because distortion increase by the non-straightness of the B-H curve. The coil with iron core forming closed magnetic
circuit (a toroidal core, an E-I core, an U-U core and e.t.c.) is especially unsuitable for a network part because
distortion will be big. On the other hand, coil with large-scale ferrite core forming open magnetic circuit will be available
because structure is near to coil without core. I recommend you to make the coil without core if you have
means to measure inductance. It is not necessary to wind coil in rows, and there is no changing in performance between
a coil being wound in rows and a coil being wound at random even if it was formed around one hand. However, I think
that you had better to practice tape winding and varnish processing or adhesive fixing because stability of the shape is
necessary.
6. A film condenser is suitable for a condenser for speaker networks.
Except a super high-cost speaker system, aluminum electrolysis condensers and coils with silicon steel sheets forming
open magnetic circuit are usually used. However, a frequency characteristic of the aluminum electrolysis condensers is
bad, and the function as the condenser is not so sure at more than 1kHz. When they become the low temperature, they
have not good reliability at all by influence of a capacitance deviation and an inferior frequency characteristic. The use
of the aluminum electrolysis condenser is limited to only low frequency, and at more than an middle frequency the use
of the film condenser is recommended. The film condenser can expect stable characteristics till the frequency more
than 100kHz.
7. The 6dB/oct and 18dB/oct network circuits have good performance.
If the characteristic of the speaker is good, 6dB/oct network circuit is very suitable and superior. There is no
phase distortion in 6dB/oct circuit, and it communicate the wave form of the transient phenomenon faithfully.
Even if a corrective circuit may be added, amount of the phase distortion can be limitted to small, but the
separation of the midrange is not clear, and you will hear an middle tone from the speaker of the low tone and the
speaker of the high tone in the case of 3 - 4way. When the change of the characteristic of the speaker is big, 
and the output in stop band is big, though phase distortion increases, a 18dB/oct network circuit is suitable.
Instead of that the separation of the midrange becomes clear, phase distortion will increase, and it does not
communicate the wave form of the transient phenomenon faithfully. However, the network circuit will be chosen
by interest because it is low level of phase distortion that is collateed with a CCIR standard of transmission of
high quality, and is estimated to be no problem.
8. When the phase difference is 90 degrees at the crossover frequency, the characteristic becomes the best.
In 18dB/oct and 24dB/oct network circuit there are about 270 degrees phase difference of the speaker voltage,
and can obtain a almost level curve of frequency response without trouble by the same aspect connection.
However, the phase distortion can be considerably decreased by making one of speakers a reverse aspect
connection and adjusting the phase difference to about 90 degrees like a level curve of frequency response.
This fact can be confirmed in the Excel design sheets for speaker network. In "SpeakerCorrection1" of excel
sheet all the cell data of "Lower cross over" and "Higher cross over" are cleared, and data of the "Polarity
after correction"is input. In case of 2way woofer only might be selected for the reverse aspect and in case of
3way sqawker only might be selected. When you select a sheet of "18dB2wayType" or "24dB2wayType" or
"18dB3wayType", and you fill the data of "1" to the cell of the "Sp correction1-4 add", you should be able to
confirm the decrease of phase distortion.
9. Phase distortion increases when you use a speaker corrective circuit.
Phase distortion increases when you use a 6dB/oct corrective circuit or a 12dB/oct corrective circuit.
Because circuit development and the theory analysis about the corrective circuit are the poor at present, they
have not watched the article in which calculated influence after the correction either. However, it is a fact that
phase changes after correction, and connection polarity of speaker can turn over depending on a case.
10. For the calculation in the resonance type network circuit must be used the formula of the band pass filter.
You can not set attenuation at the crossover frequency by the general calculating formula precisely, but you can
set crossover in -3dB precisely by using the formula of the band pass filter.
11. Even if several stacks Zin constant type networks repeat it, Zin becomes constant.
Even if the network circuit of the Zin constant type that I devised repeats the number of the arbitrary stacks, you
can design the network circuit of the Zin constant in 6way or even 11way much less 4way freely, because Zin
becomes constant. It is the different theme of course whether such large number of speakers are necessary.
The Zin constant circuit devised by the present has two kinds, 6db/oct and 12dB/oct, and there are series type
and parallel type in each. Because a characteristic is good, as for the Zin constant type of 6dB/oct in particular, 
without a limit of number of speakers freely, you can design the network circuit of the good characteristic that has
flat curves of total voltage and an electric power vs. the frequency, and has zero phase distortion.
In addition, you can use modifying the network circuit of the Zin constant type as a speaker corrective circuit for
the good point of the impedance characteristic.


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