The Double Bass FAQ


  1. Introduction
  2. All about age
  3. Materials
  4. Processing
  5. Tobring in
  6. Age and repair
  7. Recording, how to
  8. In case you need new strings
  9. Bridge adjuster
  10. About humidity
  11. Air condition
  12. The never ending drama (piezos and microfones)
  13. Piezo based pickups
  14. Microfones
  15. Strings
  16. Gut,  synthetic materials, steel?
  17. All set and done, or what?
  18. Orchestra
  19. Jazz
  20. Cleaning of strings
  21. How long do they last?

 
 

Introduction

Some years ago when I first considered buying a double bass I had no chance to ask friends about information, but there was the internet and several newsgroupgs like www.acousticbass.com and www.talkbass.com. This was realy helpful and I got a lot of tips. But most helpful was to talk to several luthiers about what is important and what not. But all in all it was very time consuming therefore I thought about writing my own double bass faq.

Obviously this kind of faq will never be complete and it lacks a lot of important topics, but I may help to do the first steps without stumbling. Very important for this to work is that you, the reader, take action and help me to find mistakes, additions and your personal experience. With regards to this I would like to mention Achim Göbel, Gerrit Hamacher, and my wife Christiane Schönharting-May.

My very special thanks go to Christian Veltman from Sweden for his nice pictures who help to make this faq more beautiful. Not to forget the people at www.geba-online.de who host a copy of these pages.

Regards,
Stephan Schönharting
(stephan@schoenharting.de)

 

All about age

Like with violins there are these rumors, that your instrument needs a certain age before you can use it seriously. This age is usually counted in centuries. And like with all rumors, there is something true about it. But only something and this is only one part of the story. There are others, like materials used, craftmanship and tobring in, which are at least of the same importance.

Material

Although not restricted to, but most common, a double bass is made of wood. But you can't go to the next forrest and cut some wood to build a double bass. As long as the wood is kind of wet, you can't use it as it bends and gets twisted while drying. This drying out is a very time consuming process if done properly and can take some years. There is the oportunity to dry wood by climate control, but by this process the wood dries out unevenly and tends to bend later on. Therefore good luthiers try to buy very old and broken double basses just for the wood.

But before drying out the wood needed to grow and this is where mankind comes into play. Environmental changes, like climate changes or toxics, have a strong influence on how wood grows. Only a very steady and slow growing leads to an even structure of the wood which has a very positive influence on the sound. For example, if during one year the precipitation was very high the wood growed quickly and makes it soft. A very dry year can almost stop the process of growing and makes a very hard wood. The same is true for toxics like acid rain and so on.

But in my opinion you can't say that only wood that is older than lets say a hundred years is good for a double bass. Even in the old days there was the prolem of how to conserve wood, and climate change did always happen (but maybe not as fast as today). In addition there was the problem of getting grip of some special materials, like ebony, which is very easy today. Therefore they took rosewood as a substitute, which does not sound as well.

Processing

Is the art of building a double bass of the former days already lost? Certainly not! Of course, the art evolved during the years as the vision and the most seek after sound of the instrument itself too. Not to forget the ways of comunication we have today and the possibility of hearing different instruments. In former days all luthiers worked more or less alone and learning meant walking across the country to meet other luthiers. Good ideas and new approaches spread very fast and easily today. Especially restauration and repair of old instruments broadened the knowledge massively. Therefore I think the most important factor it the luthier himself (or herself). If he tries to build as much double basses in no time, there is only a slight chance to build a masterpiece. As I already said, the wood needs time to dry, the glue need time to harden to avoid unwanted tension which leads to cracks. And the finish needs time to avoid harming the wood (especially true for acrylic finish).

For these reasons, you can find a good mixture of old and new double basses in the professional community. But in the end this discussion is kind of academic, as only your money and your ears can decide what you like and what you can afford.


Tobring in

On a fully carved double bass you usually take special wood, which resonates at predefined frequencies. If all parts and woods would resonate at the exact same frequency, you would get an instrument wich would sound very strange. Full feedback at that given frequency and a very dull and damped sound at all the others, like wolftones. Only the even harmonics would resonate substantially. Therefore shape, the distance from top to bottom and the resonating frequencies of all parts have to be taken into account. Typically the bottom is tuned two halfsteps different from the top. All this is done to achieve an almost even resonating corpus. But this does not mean mathematically even, but like the ear works. The lower the tone played the more energy it needs to sound with equal loudness to our ears. To be more precisely it is a logarithmic proportion.

And here comes a very important quality of wood into play. If wood is forced to resonate at different frequencies over a long period of time it changes it property. This is partially due to the resin within the wood which crystallizes over time and does this differently if it vibrates during this process. Let's think of hair. The hair is glued by resin and if it hardens all hair vibrate at a certain frequency. But if the resin crystallizes the clue can break and the hair can swing more freely. It is just an analgon, but may help to understand that matter. The time it takes for the resin to crystallize properly depends on many factors. How often the instrument is played, the surrounding climate and climate changes. This is why old instruments which were played very often may sound kind of more open and why a new instrument changes it's tonal qualities during the first years of playing.


Age and repair

There he is, our object of appetency and he is marked by the years. Almost all old and carved instruments show marks of playing and scratches or even fissures. Do not despair! This is what a good luthier is good for and quite a lot of times your instrument sounds better after the repair. Wood can build up a lot of tension and if the tension is released by a fissure it can vibrate more freely again and this is good with regards to tonal quality. But as you can imagine a fissure at the shoulders is quite hard to repair. The only obvious place to get into the double bass are the f-holes. Quite small you might think. For this reason a good luthier has a rich variety of different, often selfmade, tools. But there are situations when you have to take off the bottom. This can be a taunting task. Hopefully no one did took the wrong glue before! The proper glue can be weakend by humidity and temerature and gets the characteristic of chewing gum. So taking off the bottom is no big deal.

I remember me playing on a gig with a lot of sunshine direct onto me and my double bass. But suddenly a thunderstorm with huge amounts of humidity came up while playing. What happened was, that I got some very deep insights into my double bass while playing and while loosing the bottom of my instrument. At first I was quite shocked, but my luthier repaired it for almost no money and within a day.

So, what is the moral of this story? Never ever glue your double bass yourself to stop him from buzzing or other nasty things. Go to a luthier and let it done. If you have no chance to get to a luthier, at least order some of this special glue from a luthier. But beware, it smells like he**!

I think this is a nice moment to talk about a tip. You all know this situation, you are on a recording and suddenly you hear this buzzing while a certain pitch is played. No time for a luthier as time is ticking. Get some wax, maybe from a candle and some assistance. Find the buzzing spot while pressing the finder of your assistant on different locations of you instrument. Next put some wax on a place near this location and try to make it stop vibrating. At last go to a luthier some day after the recording. Or did it stop all by sudden? May be the room you recorded at was to dry/wet?.

The finish. I think you should be very careful here. There are so many different kinds of finish, oil based, acrylic based, water based, and so on. If you try do repair anything with the wrong finish you are into deep trouble as the finish may wrinkle up. Expensive, very expensive. Ask your luthier  at any time you are near, what kind of finish your double bass has and he may give you some cleaner for very small money. These cleaners are very good to even out small scratches.


Recording, how to

Tonight is the night. Rehearsals were intense and the decision is made. We are going to do a recording! But how do we record a double bass? Do I have to get all the technical terms straight, do I need to know all the gear that is available? This is a question of money. If you have enough money, you don't need to bother with these things, but if you don't, yes, you have to learn some things.

To start with you need some basic knowledge about recording technique and a vision about what your double bass should sound like as there are many different approaches to recording a double bass.

The most basic approach

You need a piezo pickup and a decent DI-box and you are almost set. I like the avalon U5 most, but there are lot's of different DI's on the market. But there is one important thing you have to take into account. It's called impdance. A piezo pickup can't just be  plugged into any preamp, because you need an input impedance of at least 1MOhm. Piezos don't produce a big output and if you have an impedance mismatch the sound get's thin and noisy. There are preamps like the acoustic-q which offer specialized inputs for piezos which is definitely the way to go.

If you choose a Balsereit, Fishman, Underwood, K&K, Wilson is a matter of taste. But be aware, a piezo alone can not reproduce the sound you hear when you are playing alone. You will almost always get a sound that is very close to the sound of your strings alone. You might consider a combination of piezos and microphones, but we are talking about that a little later.

If you setup your piezo, tuned your double bass and chose your preamp or DI it is time to record. Or not?

If you do the recording yourself, I would recommend using eq's at a later stage of the process. But you might consider eq-ing in the range of 100-150 Hz to get a more balanced input. But be careful, this can't be undone later!

Here some hints:

up to 50 Hz        simply cut off, there is nothing a plain stereo could reproduce with quality

100-150 Hz        here you can reduce boomy sounds

800 Hz                kind of presence

3-5 kHz               treble or brightness, definition

6-8 kHz               air, good for arco

If you have a decent instrument and setup, try to avoid compression or use it very carefully as it changes the sound and tends to pump or click.


Midsize approach

More problematic, but much more promising is a recording with a condenser. There are quite a lot of microfones on the market, but just a few are suitable for the double bass. You could choose a Neumann TLM 103, U87ai,  a ribbon microfon, or a dynamic.  Right now the ATM S25b seems to be a very nice condenser which already comes with a mounting system suitable for the double bass. The Rode NT6 with an omni capsule is also a nice and cheap solution. If bleeding is a problem, and it almost always is, you should take something with a cardoid pattern

Now it comes to positioning of the microfone or microfones. To get a balanced and natural sounding double bass positioning of the microfone is substantial. What I like most is using two mics, one with more string and another one with more body. So, if you put one mic at the end of the fingerboard pointing straight to the fingerboard you get a lot of strings, but almost no body. The second one could be put in front of the f-hole or close to this position. Now you get body but very less strings. If you blend both you get a nice sounding bass.


A similar but also different approach is to take a Rode NT6 and the ATM S25b. The Rode you should mount on the bridge with the swivel mount already supplied with the NT6. If you get yourself a screw with imperial measures, in Germany you can get it by the Astronomers supply for cheap, it can easily be mounted on the bridge using the heart shaped hole. Direct it in an angle of 45 degree downwards. Now blend it with the ATM S25b and now you have a very nice sounding double bass which is moveable!!

Sometimes you need some baffles to reduce further bleeding from the drums. Here the stuff from clearsonic is very nice.
 


Live approach

If you want to record your double bass live, you have quite a lot of difficulties to fix. I would definetely recommend to track your piezo pickup just to be on the safe side. Not that I like that sound very much, but bleeding can be a big problem and the piezo can give you some more definition. Now you could mix this signal with a microfone you like, but this time it has to be one with a cardioid pattern. And in the end you have to take care for phase cancelations. Because of the difference in time the sound travels to the piezo and the mic you will have cancelations. In addition these differences are frequency dependent as sound has different speeds reagarding to the frequency within wood. This effect could be as strong that the sum of both signals is much more quiet than each signal on its own. But most of the time some frequencies will be shifted or dampened. You can deal with this using a decent eq.


In case you need new strings

Talking about strings is very difficult. Too many aspects have to be taken into account to make a suggestion. But some basic topics can be discussed.

If your strings are worn out you need new ones. You might think, "hey, I didn't know that", but how do you determine that your strings are old? It gets more difficult if you play a lot, as strings degrade slowly and you adjust yourself to the changed sound. Usually the first thing you might notice is the lack of sustain and brilliance. But some people like exactly that, which is called "old school sound".
But after you made your decision to put up new strings it is getting much more difficult as strings are expensive and there are quite a lot of different brands and types. More about this a little later.

If you have never changed strings before, you might consider a few things in advance. First you should take the save way and change them one by one, never all at the same time, because if you take down all strings at once at least the bridge will slip and fall down. Remember, the bridge is not fixed! It only gets hold in place by the pressure of the strings. Another thing that might happen is that the soundpost might fall. In this case there is nothing you could do without a luthier and his special tools. Otherwise you could damage your instrument easily!

By the way, now would be a good time for some extensive cleaning of the fingerboard! There are some very good products available, like Pirastro String Oil, to do this. You should never ever take anything with alcohol as it would dry out the wood. One last step would be to put on some graphite from a soft pencil into the carved wood where the strings run through. This make tuning a lot easier. And at least after the first tuning check if the bridge is in place and upright or a little bit turned to the bottom of the instrument. If it is not, just loosen the strings a little bit, put your thumb on top of the bridge and hit your thumb with the fist of your other hand. Easy trick, if you hit to hard, your thumb hurts, to soft and nothing happens :-)

Another hint, don't cut the strings to short. Some more windings will help the instrument to stay in tune!


Bridge adjuster

Bridge height adjuster offer the simple possibility to change the string height by dialing the adjusters. Although this is very easy to set up, they alter can alter the sound of your instrument. In addition all bridges with adjusters can be bend more easily when new strings are set up or get tuned. Under all circumstances you should ask you luthier for help and andvice. My personal opinion is that usually you don't need them. If your instrument is set up porperly it changes according to climate changes but not as much as to render the instrument not playable.


About humidity

More to come next time!

Air condition

More to come next time!

The never ending drama (piezos and microfones)

More to come next time!

Piezo based pickups

More to come next time!

Microfones

Trying microfones is something very expensive because there is a wide variety of diffent microfones on the market. There are quite a lot of microfones starting with mics for a small budget and going up to several thounsand euros for a single mic.

Here in this FAQ I  try to focus on the special needs a double bass player has, which include moveability, different playing styles, a hassle free setup and reproducebaility under different situations. The microfones available right now are all of a very different quality and it would take too much time tot present them all in this FAQ. So only my personal favorite gets presented here.

Usually when you use microfones, you are in a recording situation and therefore feedback is of no concern. Bleeding from the other instruments can be a problem, but keep in mind that some kind of bleeding could be useful to glue the sound together. But it does this only if the bleeding is not heavily colored. This means that the sound picked up from the other instruments does not make them sound odd.

Microfones that do not color too much are often so called omni condesor microfones. This is a big advantage, but on the other hand they pick up bleeding very easily as they take the sound from every direction evenly. If you want to keep moveability high, the microfone has to be attached to your instrument. And certainly, you don't want something of high weight using big clamps on your instrument. So a small mic might be what you are looking for.


Small mics don't pick up extended bass clearly, is this a problem? Good question, and a difficult answer - yes and no. Usually all frequencies below 50 Hz are kind of muddy and can be cut off. About 100 Hz it gets different. Here the quality of your instrument gets very important, if your instrument is muddy here, no microfone can pick up something useful. But if you have a quality instrument, what could we do? Hey, just take two!
As you can see on the pictures, I usually take two very small condensor mics (2x DPA 4061 Lavaliermicrofones, omni and low sense). If you buy them in a set, you get very nice tools to fit them on your instrument, too. Below you can hear a short sample with this setup. The preamps used were an Avaln M5 for the mic on the bridge and an Avalon 737 for the mic on the strings. Only some light tone shaping was used to cut down frequencies below 80 Hz of about 3-4 db:

sample.mp3

Ok, this setup is not really cheap, but the most setups I know are even more expensive or lack moveability or do both. Even if you use just one of the miniture mics, the results are stunning. The position of the mics can vary very much depending on the strings used, the instrument played, style and  taste. Therefore the pictures above may be a good starting point. The measurement of the ruler is in cm.



Strings

More to come next time!

Gut,  synthetic materials, steel?

More to come next time!

All set and done, or what?

More to come next time!

Orchestra

More to come next time!

Jazz

More to come next time!

Cleaning of strings

More to come next time!

How long do they last?

More to come next time!