Amplifier loudspeaker ohm impedance output input voltage impedance bridging impedance matching speakers - There are no 4 Ohm or 8 ohm amplifiers - 4 - 8 - 16 resistance resitance ohms - sengpielaudio Checker
 
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Amplifier, Loudspeaker, and Ohms
How do they work together? − The misunderstood topic

It is customary for the connection of audio devices to talk of the source and
load impedance or output and input impedance. If you hear something of
an "8 ohm amplifier", then we think usually of 8 ohm speakers.

These are amateurs asking for help in the forums, where you are told
something wrong about the "impedance" of the power amplifier and
about the speakers:

Will 4 ohm speakers work with an 8 ohm amplifier?
4 ohm output into 8 ohm loudspeakers
8 ohm speaker to 4 ohm channel?
4 ohm amplifier with 2 or 8 ohm subwoofer
Connecting 4 ohm speakers to an 8 ohm receiver
4 ohm speaker on 8 ohm amp?
8 ohm speakers - 4 ohm amp?
Can you use 4 ohm speaker on a 8 ohm amp?
4 ohm sub to a 6 to 8 ohm amp
4 ohm speaker on 8 ohm amp?
4 ohms speakers on a 8 ohms amplifier?
Matching speakers to amp (4 ohm to 8 ohm)?
Can I use 8 ohms amp to 6 ohms speakers?
Can a 8 ohm speaker damage 6 ohm amp?

All the questioners go out with a great determination from the fact that the
speaker amplifier has an output impedance of 4, 6, 8 or even 16 ohms.

Now you get a big disappointment:

 
There are only power amplifiers with an output
impedance of much less than 0.5 ohms.
 
 
Accordingly, all questions are wrongly put.

When "8 ohms" is written on the output of an amplifier, that does not
mean that there is present an output impedance of 8 ohms.
 
The output jacks of a power amplifier 
 
speaker output jacks 8 ohms
right     left              

It is told here, that these 8 ohms means only that loudspeakers wit
this ohms value are desired by the amplifier manufacturer. However, it
is customary for the connection of audio devices to talk of the effective
output and input impedances − here from the amplifier and the
loudspeaker.

Calculation of the damping bridging circuit devices damping factor - sengpielaudio

Power Amplifier     → Passive Loudspeaker
Leistungsverstärker
Passiver Lautsprecher
Output impedance Zsource =   ohms   |   Input impedance Zload =   ohms
         
   Signal or load loss Δ L =   dB
   Damping factor DF =   = Zload / Zsource = Z1 / Z2
In the audio technology even for speaker amplifiers (power amplifiers), we use only
voltage bridging. The frequent call for "real" matching Zsource = Zload is really wrong.
There is no speaker impedance matching. We got speaker impedance bridging.

The seldom specified source resistance Zsource is hiding in the damping factor DF.
A damping factor of at least DF = 100 is entirely in order. Loudspeaker and
amplifier connections have a source impedance (amplifier) of Zoutput less than
0.04 ohms, with a load impedance (loudspeaker) of Zinput greater than 4 ohms.
 
Zsource << Zload or Zoutput << Zinput
 
Impedance matching (power matching) Z1 = Z2 on the other hand, is used in the
telecommunications and the RF technology applied to antennas.

Aha!
Notice:
There are no 4 ohm amplifiers.
There are really no 8 ohm amplifiers
for the 4 ohm or 8 ohm loudspeakers.

 
In audio technology, even with power amplifiers and speakers we really use voltage
bridging Zout << Zin. The frequent call for "real" impedance matching Zout = Zin,
is wrong.
 

 
There is no impedance matching Zout = Zin between power amplifier and loudspeakers.
 

No matching speaker impedance (load) to amplifier - No loudspeaker load impedance
matching - Matching is a myth. We got speaker impedance bridging Zsource < Zload.

That is an ineradicable myth. The output impedance of the amplifier is always a
tenth or a hundredth of the value of the loudspeaker impedance. The value of
the output impedance of the amplifier
Zsource is always hidden in the damping factor DF and can easily be calculated:
 
Zsource = Zload / DF
 
Zload is the impedance of the loudspeaker.
The cable resistance (impedance) is a part of the output impedance of the
amplifier. Because of the high voltage of the source, cable screening (shielding)
is not necessary in this case.

The typical continuous query in the forums: "Can I use 4 ohm speakers to a
6 ohms amplifier?" (See reply under "Notice".)

These issues show that there must be storytellers underway. How can we get
rid of the nonsense of 2 to 16 ohms amplifiers?
The output impedance of an amplifier Zout is always smaller than 0.5 ohm.
Zout << Zin.

Amateurs are happy to speak of an 8 ohm amplifier, if they think not correctly
that the amplifier output should be connected to "8 ohm speakers".
Dealers use exactly these unclear expressions. In reality, the speaker
impedance curve of a loudspeaker is never a stright line; see:
Typical loudspeaker impedance curves vs. frequency

Impedances behave like an unloaded voltage divider. Zload = Z1and Zsource = Z2.

Signal loss in dB: 20 log [Z1 / (Z1 + Z2)]

Damping factor: DF = Z1 / Z2

Source impedance in ohms: Z2 = Z1 / DF

Please enter two values, the third value will be calculated.

Damping factor DF:    Magic Triangle DF
Load impedance Z1 = Zload    :  ohms 
Source impedance Z2 = Zsource:  ohms 

Z1 = load impedance and Z2 = source impedance.

Calculation of the damping of impedance bridging or
power matching an interface connecting Zout and Zin

Calculations: voltage divider (potentiometer) -
damping pad - loaded and open circuit (unloaded)

Please tell your friends: There are really no 4 or 8 ohms amplifiers to match the speakers.

The damping factor is usually given as numerical value, but also in decibels.

Enter a value in the left or right box, then press the TAB bar or make
a mouse click at an empty space at the side, to get the solution.
The calculator works in both directions of the ↔ sign.

Damping factor DF as number: 
Zin / Zout		  ↔  Damping factor as dB value:
dB
Formula DF   Formula in dB
DF = 10 ≡ 20 dB            DF = 100 ≡ 40 dB

Calculation of the damping factor.

How do I calculate the damping factor DF for example, at 1 kHz, if neither the impedance of
the source Z2 nor the impedance ofthe load Z1 is known?
Allow the source to send out of a 1 kHz sine tone and measure the resulting voltageV0 at the
output without any load. Then measure at this point the voltage VL, when the load is applied.
The damping factor is:
DF = Zin / Zout = VL / (V0 − VL)
(V0 − VL) is the voltage drop by the connected load.

The impact of input impedance and output impedance
of studio gear for bridging in audio engineering

Measurement of input impedance and output impedance
Calculations: voltage divider or potentiometer − Loaded and open circuit (unloaded)
Bridging (voltage) or matching (power) − Interface connecting Zout and Zin impedance
Voltage bridging or impedance bridging − Zout < Zin
Cable length, cable capacitance, and treble loss (Attenuation, cutoff frequency)

Fortunately, there are no amplifiers with an output impedance of
4-ohm or 8-ohm which have to fit to speakers with these values.
We have no power matching, we have voltage bridging, whereby
the power amplifier often has an output impedance of only one
hundredth of the speaker's input impedance.

At power amplifiers for musicians usually you can read at the
output plugs: 4 ohms to 8 ohms − to tell the user that only a
4-ohm speaker or an 8-ohm speaker has to be used and does
not give the "correct" output impedance value, which is around
0.1 ohms. This is often not known by users.

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