Double bass

Amplification of double bass is a hard job!

In general, amplifying a double bass is more difficult than amplifying a bass guitar. The intention is that the amplified sound resembles the acoustic sound of the instrument as much as possible. Sooner or later every bass player will find out that this cannot be achieved for the full 100%. The problem is easy to understand: the sound box vibrates and sets the air in motion. Using an amplifier means that not the instrument sets the air in motion, but the paper cone of the loudspeaker. The difference in material (wood versus paper) causes a different sound. In addition, the used pick-up and amplifier also influence the sound.

The last decades, amplification of double basses has been badly served. The standard double bass combos  overemphasized the mid registers of the sound spectrum; real low and high tones were almost absent. The fact that this rather bad reproduction has been a standard for so long seems almost  unbelievable, especially when you realize that amplification for bass guitars improved substantially in the same period.

To this very day, many double bass players use these midrange combos. The cause of this not only lies in habituation and imitation. The presence of  the mid tones as described before  makes the bass sound clearly audible on stage. Apparently, bassists were prepared to put up with the lack of low and high tones. Moreover, most bass amplifiers and combos on the market were and are more suitable for bass guitar than for double bass: there wasn’t much of a choice.

Hevos has worked out a few combos and amps that are specially suitable for double bass. Read more about these amps, combos, loudspeakers and pick-ups on the next pages.

Pickups for double bass (info Jonas Lohse)

Click at the pictures to link to the producer.

akg c4500b

Pick ups do what their name suggest: they pick up the sound of the double bass. Pick ups can be classified in three groups: microphones, contact pick ups and magnetic pick ups.

The so-called dynamic microphone, which is often used for singing and live performance, can be used for amplifying double basses. The use of this type is common in studios, where acoustic circumstances are more or less ideal.

condensmic

In live circumstances the condenser microphone is very useful for double bass. This type is often very small and can be attached to the double bass with ease. A disadvantage of the condenser microphone is that it needs a phantom power supply, which is not available at many bass amplifiers.

Furthermore, the output signal of a condenser microphone is so small that the use of a separate pre-amplifier is necessary. Another problem in using a condenser microphone is that its positioning is critical: a few centimetres more to the left or right often changes the sound radically. Studio recording does not encounter these problems, so the use of microphones is common there.

fullcircle

More common is the contact pick up. At the picture above one sees a qualitatively very good example, the Fishman Full Circle.

bband

The contact pick up is usually fixed up or under the bridge and transforms the vibration of the top into an electrical signal. The most common contact pick up is the piezo pick up, often designed as a small flat copper sheet. The piezo pick up is very popular amongst double bassists because it is user-friendly. The differences in sound between the various piezo pick ups are quite big. Some pick ups deliver a warm sound with an abundancy of low tones, others deliver more mid and high tones. This makes choosing the right pick up quite an undertaking.

shadow

The decisive factor in the process of choosing the right pick up are the acoustic properties of the instrument. A bass that produces deep low tones will benefit from a pick up that produces a lot of mid-high tones, whereas a double bass that sounds a bit thin in the lower registers will benefit from a pick up that pushes up the low tones.

underwood

The contact pick up is usually fixed at the bridge of the instrument. Best known type is the piezo pick up. This is a very easy to use pick up, but they differ very much in sound, from tight low but lean mid/high to the opposite. Choosing the  right one is difficult.

The decisive factor in the process of choosing the right pick up are the acoustic properties of the instrument. A bass that produces deep low tones will benefit from a pick up that produces a lot of mid-high tones, whereas a double bass that sounds a bit thin in the lower registers will benefit from a pick up that pushes up the low tones.

lohse

A disadvantage of piezo pick ups is that their impedance is high. As a consequence, the input impedance of the used bass amplifier should be very high to match the pick up and to handle the signal properly. Most bass amplifiers have an input impedance that matches the needs of bass guitars. As a result, double basses with piezo pick ups sound thin, the lower tones are almost absent. Hevos amplifiers have a very high input impedance so that all piezo pick ups can be connected directly, without the use of any special pre amp.

schertler

Experimenting with different pick ups is therefor inevitable. The use of 2 different pick ups can increase the bass sound too!A disadvantage of piezo pick ups is that their impedance is high. As a consequence, the input impedance of the used bass amplifier should be very high to match the pick up and to handle the signal properly. Most bass amplifiers have an input impedance that matches the needs of bass guitars. As a result, double basses with piezo pick ups sound thin, the lower tones are almost absent. Hevos amplifiers have a very high input impedance so that all piezo pick ups can be connected directly, without the use of any special pre amp.

A pick up that is less common is the electro dynamic pick up. It is often fitted to the top and its electric working is similar to the dynamic microphone, the difference being that the pick up is not put into vibration by air movement but by the top of the instrument.

magnetischpu

Finally there are magnetic pick ups, fitted right under the (metal) strings. They work by the movement of the string in the magnetic field of the pick up, causing an electric signal. The pick up of a bass guitar belongs to the same family.

Amplifiers  for double bass

As already mentioned above, a high input impedance of the amplifier is very important. Thanks to the very high input impedance of HEVOS amps, even the most exotic piëzo pick up can be connected without quality loss and without the use of an extra pre amp. However, the higher the input impedance, the more sensitive an input is for all kind of near field electromagnetic interferences. So there has to be a balance between the demand for a high impedance on the one hand and an undisturbed sound reproduction on the other. HEVOS amplifiers have an input impedance of 5 MegOhm. From a viewpoint of electronic engineering it is very easy to increase that impedance, but that would also increase the amps sensibility to disturbing signals. Furthermore, it is not necessary to do this, since 5 MegOhm is high enough to cope with all kinds of piezo pick ups. At the same time, you will enjoy a noiseless amplification.

Needless to say, a good amplifier should amplify and should not colour the original sound. That would certainly hinder the pure reproduction of the acoustic sound. Of course it must have an effective tone control. The acoustic differences between double basses make it sometimes necessary to adjust the sound, and so do differences between pick ups. Furthermore, bad acoustic circumstances on stage or in the hall make a good tone control an essential part of the bass amp.

Some double bass players like to use a condensor microphone to aplify their instrument.

condensmic

A condensor mic needs an extern power supply of 48V though, called phantom power supply. And the Hevos 400C amp lacks a phantom power supply. From an electronic point of view designing a phantom power supply is a piece of cake. The reason why we did not do so is because very few bass players use condensor mics nowadays. Furthermore there is not much room left inside the 400C for an extra input.

To serve our clients well Hevos delivers an extern phantom power supply if desired. There are several typs/brands available, but we have a preference for these two because of their good quality:

icon fantoom
Icon Neo Phantom

samson fantoom
Samson S-Phantom

Both types are small and have 2 inputs and outputs, so one can connect 2 mics if desired. A power adapter is supplied.