Balancing String Bass & Cellos

[ejr]

Does 1 string bass = 2 cellos? If so, in general terms, when would you want to break this "rule"?

I am writing for a small pit orchestra with one string bass and two cellos. I sometimes encounter a situation where I want to have the cello line doubled by the string bass an octave below (cello and bass parts being played arco). Almost as frequently, I have a bass line that alternates between cello & bass in unison and divisi (again, cello and bass arco). In these cases, do I want to have two cellos on the cello line or just one? What will balance best? I am looking for a blended sound here, where the individual instruments are not easily distinguished. Just a nice, solid support for the higher instruments that doesn't call much attention to itself.

Elsewhere in the score, the bass is played pizz and functions more like part of the rhythm section and the strings are divided in one of two ways: 2 part harmony with unison violins over unison cellos, or unison violins over divisi cellos (with the first cello playing what would have been the viola line.) This seems to be working quite well.

But I hear little difference between using one cello or two with the bass as described above. I am not sure that I can trust my software because it is just too easy to adjust the volumes of the virtual instruments to make them balance (especially when I am using samples from different libraries that were recorded at different levels and some compensation is needed in any case.)

Thanks.

[Poolman]

Two instruments of the same type are not twice as loud as one. It takes 10 violins to sound twice as loud as one (standard acoustical knowledge), and this works out as a 23% increase every time we double the number of instruments. So it is only to be expected that two instruments in unison will not sound much louder than one. When two instruments play in octaves however, this appears far more like double volume subjectively (say 160%)

Be careful if your cello(s) and bass alternate between unison and octaves; you can see that this makes the subjective loudness vary.


Terry

[Ranger]

try separating the instruments by pushing one more right or left in the mix

[sonata5920]

Gday ejr,

I assume, that you want to balance the sound of acoustic instruments

The bowed double bass produces a SPL (Sound Pressure Level) of +3dB above the SPL of a cello. The SPL of two cellos add up geometrically (as in total SPL= square root over [SPL1 squared +SPL2 squared]) to +3dB confirming your statement.

At the low pitch end of the instruments, the perceived sound level drops off dramatically over one octave, perhaps by 20 dB at lower SPL. At a concert, people in the last row of the concert hall usually do not hear the double bass at all.

Best wishes,

Herbert

PS: It takes four violins to produce twice the SPL as square root of 4 equals 2.

[Dean L. Surkin]

Both Sonata 5920 and Poolman are correct, but Poolman's answer is more useful for the OP's question.

The dB scale is logarithmic to base 10. An increase of +10 equals ten times the acoustic energy. I.e., if one jack hammer generates 115 dB, ten jackhammers generate 125 db. An increase of +3 represents twice the acoustic energy.

However, our ears operate logarithmically. If it were otherwise, we could never hear the dynamic range that would allow us to survive in the wild (enduring the sound of thunder without permanent damage all the way down to hearing a breaking twig that signals the approach of a predator). Since we hear logarithmically, and increase of +10 dB has the psycho-acoustical effect of twice the volume.

Thus, as guitar players eventually learn, a 100 watt amp sounds only twice as loud as a 10 watt amp going through the same speaker cabinet (more expensive amplifiers often have more efficient speaker cabinets, but that's a different topic).

With all this in mind, it does take 10 violinists to sound twice as loud as one violinist.

Finally, we can't ignore the acoustics of the performing venue. I once attended a concert, seated in the mezzanine of the hall, where all frequencies below about 100 Hz were sharply attenuated, perhaps 20 to 30 dB, with frequencies below 50 Hz inaudible. So the basses would have needed amplification of 1000 watts to restore their balance. Alternatively, a re-design of the concert hall would have helped.

[ejr]

Okay, I'm confused. Your answers have a lot more detail than I think I need. And, while interesting, I don't see a clear cut aswer to my question: Do I want to use one cello or two when playing in octaves with the double bass (or alternating octaves and unison)?

[DPDAN]

Okay, I'm confused. Your answers have a lot more detail than I think I need. And, while interesting, I don't see a clear cut aswer to my question: Do I want to use one cello or two when playing in octaves with the double bass (or alternating octaves and unison)?


I don't blame you for being confused.

Let's see, a cello when played arco produces 72 decibels at one meter, but when compared to a flute producing 72 decibels,, the distance of one meter and the frequency of the note that the flute is playing needs to be subtracted from the root of 14.7 decibels to the fourteenth power of 20KHz. :rolleyes:

In my opinion, it really depends on the players and their instruments.
I would have both cellos play the same octaves, and let the bass play the lower fundamental. On the last note of each song if the cellos can play the root, let one of them play the same octave as the bass for additional color and emphasis on the low end.
Dan

[sonata5920]

Gday,

ejr – My apology, my post may have been a bit cryptic to you. What I meant, was that you are right, two cellos equal one double bass in volume. But this is only true if you stand close to the musicians. As you move away to the back of the concert hall, the double bass playing one octave below the cellos, will increasingly sound fainter, compared to the cellos. There will be no balance of sound at the back of a larger hall, due to the characteristics of our hearing (loudness).

The fact is that you cannot balance low notes an octave apart for the whole of a concert hall, unless it is a very small concert hall. If you know the dimensions of the concert hall, it is easy to predict a point, say half way down the concert hall, where you could expect a reasonable balance between cello and bass. One cello and one base could be a reasonable compromise. Of cause it would also depend on the musicians.

Dean – You must be careful not to mix up energy, power and SPL (Sound Pressure Level). Our ears do not register sonic power or energy but SPL, just as microphones do. For SPL ratios as well as for microphone voltage ratios, the dB is used as: level=20*log(V/Vo).

A 100W amp is not only twice as loud as a 10W amp. The power ratio=square root over 10 = 3.2.

The SPL of 10 violins equals 3.2 times the SPL of one violin.

Best wishes and Marry Christmas,


Herbert

[ejr]

Thanks for the clarification. I should have said that this is for the theater, where the string bass is almost always played into a mic (as would be the case for the violins as well in most houses and all the instruments in the larger ones). So, the ACTUAL balance (volume) would be controlled by the mixer as well as the conductor. What concerns me is making a small orchestra sound as close as possible to a larger one when amplified. It's about the PERCIEVED weight, depth, or richness of the sound (but perhaps I am not using the best descriptors here).

Maybe the best way to ask the question is simply: What would just "sound better", assuming that all the instruments could be heard equally well, through the electronics? In that case, I think what you are saying is 1 bass = 2 cellos and to keep the parts at least an octave appart.

[DPDAN]

Two cellos does not equal one bass, two cellos equals two cellos. That's like saying two bassoons equal two french horns.

They sound totally different, and since there is mixing involved,
it will be up to the mix engineer to balance the instruments as he or she sees fit.

If you are asking for arranging opinions, there is no clear cut answer. It would totally depend on the style of the music and the emotion that is trying to be conveyed.

Having both cellos play just an octave above the bass is kind of a waste of the cellos. To me, the cellos should be playing a harmony hovering a fifth up from the bass line, but not constantly.... it just depends.

Dan

[Dean L. Surkin]

Herbert:

You're exactly right about the logarithmic formulas, but I was referring to the psychoacoustic properties. I remember reading years ago that 10 dB increase in SPL subjectively sounds twice as loud to the human ear. I just did a quick Google search to see if my memory was wrong, and I found a few sites saying the same thing. Here's an example: http://www.sengpielaudio.com/calculator-levelchange.htm. Of course, information on the Internet is always suspect.

I think we were comparing apples and oranges, SPL and perceived loudness.

[sonata5920]

Dean,

You said:

“Of course, information on the Internet is always suspect.”

This is so. However Eberhard Sengpiel is a highly respected and well qualified engineer. You can trust him.

We have been taking about different things. ejr was trying to mach sound levels. Here SPLs need to be matched.

You were right when you said:

“I think we were comparing apples and oranges, SPL and perceived loudness.”

To come back to the OP’s original subject, we now know, that ejr’s orchestra is supported by a sound system. This makes things different. I still would use two cellos with one double bass, when doubling the cellos one octave below. Doubling cellos with basses one octave below is often used and good orchestration, when a fuller sound is required. It just depends on the music.


Best wishes,

Herbert

[ejr]

Of course, I am not "wasting" the cellos by doubling the bass an octave higher THROUGHOUT the score. I was simply asking for whether I should use both cellos (or just one) for those times when doubling the bass in this manner is necessary and appropriate. In deciding when and how to use harmony, I am guided by the style of piece, the instruments available and their relative "weight".

It's not so much their volume that is at issue because they can be mixed to sound balanced; it's whether 2 cellos or one on the upper octave will sound better. By "better" I mean what will make the orchestra sound larger and fuller than it actually is. I am finding that sometimes using more harmony helps. Other times, octave doubling, or having more instruments in unison does the trick. In the portions of the score that I am referring to here, doubling the bass at the octave seems to produce the best effect. The sticking point for me is trying to decide whether one or both of them should play the upper part. And the impression I am getting is that two is better. I corresponded with someone who has orchestrated Broadway shows and he says that he writes one cello part and has two players on it, throughout. I have a copy of the score for COMPANY and this is how Jonathan Tunick used the cellos as well. So, I am now feeling that doubling the cellos (whenever I don't need them to be divided for harmony) is probably the best approach for me.

[Raymond62]

....To me, the cellos should be playing a harmony hovering a fifth up from the bass line, but not constantly.... it just depends. Dan

The "oldies" often used the basses to play one octave lower than the celli.
See: Symphony 5 Schubert, most of the symphonies of Mozart (as I remember well), etc.

Raymond