Headphone amplifier

© N. Lehmann 2004-2009 - All rights reserved
Reprinting and reproduction (also in extracts) only with reference to the source
Lehmannaudio Dipl.-Ing. Norbert Lehmann Richard-Zanders-Str. 54 51469 Bergisch-Gladbach
Tel.: 02202 - 280 62 40 Fax: 02202 - 280 62 39 email: info@lehmannaudio.de

Why headphones?
With headphones, excellent music reproduction can be achieved at a fraction of the price of
that would have to be spent on a comparable high-quality loudspeaker-based hi-fi system.
based hi-fi system. In terms of resolution and dynamics, high-quality headphones
headphones are not only in no way inferior to the best loudspeakers, but are in most cases
superior to them in most cases. There is also the option of listening at night or
enjoy music even at night or in less than perfectly quiet environments. The former maintains
peace, e.g. within the family or with neighbors, while the latter keeps out environmental
environmental noise.

What makes headphones different?
There are a number of parallels between (dynamic) headphones and loudspeakers.
Both are - technically speaking - complex loads for the connected amplifiers
and should therefore be operated at rather stable outputs. There are high-impedance
headphones, which in principle require a higher voltage level and
low-impedance versions, which require more current to achieve optimum results.
deliver optimum results. If you simply plug any headphones into a correspondingly labeled
output socket without taking into account the characteristics of the headphones in question
headphones, the result can be very disappointing.

As with loudspeakers, there is an immense variety of designs for headphones.
designs. Common headphones, however, have impedances between 30 Ohm
and 600 ohms. If you transfer this to loudspeakers, for example, you would get a
range between 4 ohms and 80 ohms. The same signal voltage therefore results with
headphones only due to the impedance in power differences of up to about twenty times!
twenty times!
Regardless of the impedance, headphones, like loudspeakers, have very different efficiencies.
efficiency, i.e. they convert the signal voltage applied to the headphone output
more or less effectively into acoustic energy. With loudspeakers
loudspeakers, the measure of effectiveness is usually the sound pressure achieved at 1W
power (dB/1W). The same applies to headphones, although here the
dB/mW, i.e. the sound pressure achieved at 1mW power (not per milliwatt!).
(not per milliwatt!), which is 1/1000 watt.

Every time the power is doubled, the sound pressure increases by 3dB. Conversely
headphones with a 3dB higher efficiency require only half the power to reach the same volume.
power to achieve the same volume. The rule with the 3dB more sound pressure
per doubling of power applies equally to headphones and loudspeakers. From the
efficiency, it is easy to calculate the power required for a desired sound level.
desired sound level. The power required for the same sound
sound pressure level can vary between the different headphone models by a factor of approximately
factor of 500 (!) for different headphone models.

Ultimately, when using and selecting headphones and headphone
headphone amplifiers, the decisive factor is whether the desired volume can be achieved without distortion.
can be achieved without distortion. Of course, it is also important at what level the respective
headphones or - far worse - damage your own hearing. The
maximum load of the respective headphones is usually specified in the data sheet as
maximum power. This in turn can be used to calculate the maximum voltage
that may be applied to the headphones. If the headphones are overloaded, i.e. there is
too much signal voltage is applied, the voice coil will burn out.

Strain on the hearing
Despite all the pleasure you can derive from listening to music, you should pay particular
the health of your own hearing when listening with headphones. For the
permissible acoustic exposure of the hearing depending on the duration, there is in
the so-called Workplace Ordinance, a federal law that has been in force in its current form since
federal law in force since 1975. This stipulates that - roughly simplified - the
exposure to noise at the workplace during so-called "other activities" must not exceed 85dBA (weighted
continuous sound level) must not be exceeded. In other European countries
similar limit values apply. The duration of a working day, i.e. eight hours, is assumed here.
is assumed. Again, there is a formula with 3dB: For every 3dB more
sound level, the permissible exposure time is reduced by half. The
table below shows that with increasing sound levels, very short permissible
permissible times are reached very quickly.

Permissible exposure times

These times should be taken seriously, as it has been proven that damage to health
damage cannot be ruled out (recourse claims against the polluter).
the polluter). It is therefore advisable not to put on the headphones until the volume has been
volume has been set accordingly beforehand in order to avoid unforeseeable acoustic
to avoid unpredictable acoustic strain on your hearing.
TIP: The data for any dynamic headphones can be found together with a
voltage level on the website www.kopfhoererverstaerker.de in the free online headphone
free online headphone calculator. The result is, among other things
the resulting volume level and can use the table above to assess how long
table above to assess how long you should expose yourself to the maximum volume level.

CONCLUSION
It is easy to see that even within a manufacturer's products there are major differences in terms of impedance
differences in terms of impedance and/or effectiveness. For
For this reason, it is important to either select the headphones and the headphone
headphone amplifier directly together, or a headphone amplifier with adjustable amplification.
adjustable headphone amplifier that harmonizes with most headphones on the market.
headphones available on the market.
1 All specifications are taken from generally available manufacturer data sheets and were partly converted from other data.
converted from other data. For voltage and power, the RMS value and not the peak value is given.
and errors excepted. All data without guarantee.

Delivery
Our standard delivery is free of charge from:

• Germany 90,- €
• Austria 200,- €
• Switzerland 300,- €

Return shipment

• A return shipment from Germany costs € 5.90

Please register your return with us, then you will receive a return slip by e-mail. This ensures that the return is always sent to the correct address.

The delivery times can be found in the delivery status display on the item. Click here for the detailed delivery status display.