Mozart: Mozart – Symphony No. 35 in D, K. 385 (Haffner) (Click to view)
Beethoven: Coriolan Overture, Op. 62; Symphony No. 4 in B flat major (Click to view)
When comparing any two examples of any created work we must be careful (as far as is possible) to consider it objectively, eschewing the subjective. These two pieces by Mozart and Beethoven are both powerful and multi-faceted, requiring a broad palette of tonal colour to be available to the conductor. I’ve listened to both pieces a number of times by both ensembles and what differences exist I believe can be whittled down to two factors: number of musicians in the orchestra and physical construction of the instruments themselves.
Number of musicians:
As mentioned in the textbook, (p. 139) getting musicians together to rehearse and perform was (is) an expensive and involved task. It generally fell to the wealthy few to arrange and subsidise the creation of even a small orchestra so it became more usual for ensembles to have as few musicians as possible to create the desired aural effect. Modern musicians with access to arts funding, large concert halls (with accompanying large ticket sales), corporate sponsorship, recording deals and concert hall residencies may still feel financial pressure but the money will become available if the product is right. Employing more musicians for a particular section will allow for a more robust overall tone with an evening-out of inconsistencies merely by having more instruments playing the part. This effect can be seen weekly on BBCs “Songs of Praise”. One old lady singing a hymn in a Cathedral on her own might sound a little “off” and weak but when we get two hundred of them singing at once and the inconsistencies are evened out and it sounds delightful.
Construction of the instruments:
When a bow is drawn across a string a set of resonant frequencies (one big fundamental with lots of weaker frequencies underneath it) are set up and we hear the tone of the instrument as expected. Different instruments do this in different ways which is why (along with attack and decay characteristics) a trumpet sounds different to a violin. The construction of an instrument has an enormous bearing on its overall tone.
In the eighteenth century, instrument manufacture (especially for stringed instruments) was very different and presented problems that don’t really exist any more.
Modern cutting tools give the luthier cleaner, more accurate cuts which would allow her to join two pieces of wood with greater accuracy. Modern PVA (white) glues and refined hide glues are stronger with greater resilience to moisture, shocks, etc., making a more stable instrument. Consider just one joint, where the neck joins the body of a violin or cello. This is a notoriously weak area so string tension must be kept to a manageable level, allowing the instrument to play without running the risk of it folding in two under the tremendous pressure in that one small area.
Modern glues and accurate cuts have allowed instruments to be strung with more robust strings at a higher tension, allowing greater amplitude to be pushed through the bridge to the body which in turn sets up a stronger (not just louder) resonance and allows the instrument to sing.
Couple this with the greater number of musicians as mentioned previously and we experience a different tonal quality from the two orchestras.