Most writings on the history of the early clarinet are based on theoretical knowledge and this means that in a lot of cases the same old history is churned out yet again. I hope that you will find this article slightly different in that it is based on my personal experiences with early clarinets, from measuring them and making them, and most importantly, playing them.
One of the earliest instruments we know of is the J.C.Denner chalumeau, which is in the Bavarian National Museum in Munich. It has a recorder-like bell with two diametrically opposed keys (but no speaker pipe, as far as we know) and very little flaring at the lower end. The bore is very large at 15mm., and the tone holes are small, being on average only 5mm in diameter. It is possible that this was an early experimental instrument by the Denner family, as it does not play at all well, the tone being very muffled and restricted. I think that this is due to the bore being far too large and the tone holes too small, as well as the non-existent bell; and as it stands, it cannot have been a very successful instrument, although probably quite a novelty.
It is possible of course, that it has been bored out at some stage (this is occasionally found on clarinets; as the pitch was raised, they were bored out to sharpen them). Incidentally, it will play in the clarinet register with the back key open, and if this was intentional, it leads us to speculate whether this is a chalumeau or a clarinet. What is the definition of a chalumeau? It is possible that the higher-up speaker key (with its tube into the bore) was merely an improvement to stop water coming through the bore.
There are two other things worthy of note on the J.C.Denner chalumeau - first the keys and second the length. The keys are mounted on the mouthpiece joint, and this joint is almost as long as the body joint. You can see from the photograph that the keys are very long, and you have to be careful when assembling the joints as the keys protrude from the end. The length of the whole instrument seems quite strange at first, as it is even shorter than the Denner D clarinet (which is a tone higher). The reason for this strange phenomenon is very simple; it is entirely due to the lack of a flared bell joint.
It cannot be said for certain who invented the first true clarinet with a proper speaker key and a flared bell, as there is not enough documentary evidence or instruments surviving. There is a strange clarinet in the University of California. The middle joint appears to be stamped J.C.Denner, and the bell has a third key on it. I have not seen this instrument personally, but I understand that positive identification is difficult because the stamp is almost illegible.
The mouthpiece joint is missing. Also, the bell (with its third key, which is not found on other clarinets for another 50 years) is not stamped; all other Denner clarinets have stamps on the bell. Add to this the notorious practice of name stamps being passed down through generations, and you can see that the whole position becomes very unsure. The bell joint could easily be a later addition, as this style of bell is still found on clarinets made 40 years later (see the Zencker clarinet). It is, however, very interesting that the other two keys are not diametrically opposite and it is provided with the improved speaker key.
If the middle joint of the above instrument is genuine, then it seems that J.C. Denner may well have invented the first clarinet with a proper speaker key. In either case, we cannot assume that the enlarged bell was developed at the same time as the correctly placed speaker key.
One thing that is sure is that Jacob Denner (died 1735) made very fine clarinets. They are beautifully turned instruments, with a speaker key, a key on the front, and a large flared bell. They are made in boxwood with brass keys, and have a large bore of about 14.7mm. with quite large finger holes. The D clarinet is in three joints: a short barrel and mouthpiece combined, a middle joint, and a bell, which is almost as long as the middle joint and incorporates the lowest finger hole. On the C clarinet, the middle joint is split into two joints.
The mouthpiece has no table as such, and if you take the reed off there is just a large slot underneath. It is also very large compared to a modern one, and will take a soprano saxophone reed quite comfortably. The result is an extremely flexible and loud instrument, which sounds like a trumpet in its clarinet register. I have played this instrument in the Bach B-minor Mass, where people in the audience did not realise that baroque clarinets were being used instead of trumpets. In fact, I would suggest that it is very possible these clarinets were sometimes used instead of trumpets for such pieces.
On two-keyed clarinets there is no key to produce a B between the two registers, all fingers down giving a written C. However, there is no problem in getting this B, as the clarinet is so flexible that the normal fingering for Bb can be lipped up to obtain the B. In fact, almost all notes can be lipped up or down about a semitone. The pitch of these instruments by Denner is between A-415 and A-420, and they are in C and D.
I should mention here the notes that can be obtained on these clarinets. In the low register the number of "good" notes is restricted to the scale of F, and there is of course no low E. In the clarinet register all the notes are available, and the only difficult ones are (going upwards) C#, Eb and G#. Works written at this time use the clarinet register mostly, and when they do digress into the low register, it is usually for basic arpeggio passages.
From playing these instruments, it is obvious that the embouchure was completely different from that of a modern clarinet. A soft reed is necessary, together with a very relaxed embouchure. This helps to widen the twelfths which otherwise are very narrow, and it is probable that to play with the reed on the top would also assist.
The Zencker D clarinet in the Nuremberg Museum represents the next stage in development, and is dated at about 1740. From the outside it looks very much like the Denner D, but importantly it has a much smaller mouthpiece (only 11mm. across at the tip), and a smaller bore of 13.5mm. Also the mouthpiece has a table under the short reed. The result is a slightly sweeter sound, not quite so trumpety or flexible, and capable of producing a high G. It probably dates from about Molter's time and is ideally suited to his concertos. I have a recording of Mr. Snorrason of Iceland playing the A major concerto on one of my Zencker copies, and it certainly sounds very impressive (and difficult!). The range of notes produced is the same as the Denner, except that the middle B is more difficult because of the reduced flexibility. However, the very high notes are easier due to the smaller mouthpiece.
As clarinets became gradually less flexible, so it became necessary to have a third key on the bell section to produce a proper B. One of the earliest of these instruments is by R.Paur (or R.Baur), and it is a C clarinet in the Nuremberg Museum. It is dated about 1765 and again has a very small mouthpiece and a bore of 13.8mm. The third key is on the back of the bell and is operated by the thumb. Although this seems a curious way in which to operate the B key, it should be pointed out that with the key on the back it was still possible to play the clarinet with either hand on the lower joint. In fact, this must have been a common problem, because this particular clarinet has two G/D holes (covered by the little finger), one of which is sealed by a wooden plug. So even with a third key, the clarinet is still ambidextrous.
There are two clarinets by J.B.Willems in the Brussels Conservatoire Museum that show two developments in design. Willems was a Brussels maker working in the period 1760-1800. The first is a four-keyed C clarinet similar in shape to the Paur. The fourth key is for Ab/Eb, and the E/B key is again operated by the thumb. The second instrument is later and is in A. It has five keys (the E/B key is now operated by the little finger), and the lower part is split into two sections. So for the first time we see a separate bell joint with no keys on it. It is in fact a standard continental classical clarinet, except that the barrel and mouthpiece are still in one piece. We now have an instrument that is much sweeter in tone and has completely lost the early trumpety sound. They are now mostly pitched in Bb and C, with the occasional A, and the D clarinets (which were once the most common) have become rare.
If we now look at clarinets of about 1800, we find that they have five or six keys and a separate mouthpiece. This means that the mouthpiece can now be made in a much harder and more stable wood - usually ebony. It also has become slightly larger and is about the size of a modern Eb clarinet mouthpiece. These clarinets were probably still played with the reed on the top, as name stamps are usually found on the reed side (i.e., on the top).
The English mouthpieces had long tenons which went right through the barrel joint and butted against the tenon of the upper finger joint. They were mostly standardised, which makes it easier when it comes to replacing them (mouthpieces are only rarely usable on early clarinets, as they are usually broken or too short). A lot of mouthpieces are stamped "J.Wood", and he seems to have made most of the mouthpieces for English makers. They had cylindrical bores of about 14.3mm. on the Bb and 14.1mm. on the C. On the continent things were very different, and many different conical bore sizes were used. The continental mouthpieces had short tenons and a raised ring to hold on the ligature cord. They were also slightly larger than the English pattern, although they were often very narrow at the tip and the slot was smaller.
On all the mouthpieces of this period, it is best to have a tip opening of less than 1mm., combined with a fairly soft reed. If the mouthpiece is more open or the reed too hard, then the forked notes become very muffled and difficult to obtain.
The bodies were still made in boxwood and the keys brass (they were mostly sand castings). The springs were riveted onto the keys and were also made of brass and burnished to harden them. The supporting rings around the sockets were now usually ivory, whereas they were once part of the wooden body. The pitch by this time was A-440. Most of the baroque ornamentation had disappeared with only the ivory rings being slightly ornamentally turned.
The keys on a standard five keyed classical clarinet are speaker, A, G#/Eb, F/C, E/B (which is now operated by the left hand little finger). A sixth key is very common, and on continental instruments this is a C#/G# key, while English makers preferred a long key on the side of the top joint to give a B and C over the break, which is actually very useful for quick passages that ascend to B or C and back down again.
It is interesting to note that on all these early instruments the G#/Eb hole is below the G/D hole. This is necessary in order that the little finger on the right hand can cover the G/D hole, and consequently the Eb hole is enormous and usually still flat in pitch, while the D hole is small and drilled obliquely downwards into the bore. This problem was not solved until later, when Muller provided a key instead of the finger-hole for this note.
This classical system of clarinet lasted into the 1830s without much development apart from adding more keys to the basic framework (anything up to 13). Even with this number of keys, it is rare to find one that has a thumb rest. The occasional German clarinet has a thumb rest, and it is usually integral with the wooden body. One thing worthy of note is that the basic fingerings remained the same, and the additional keys were used only where necessary in order to improve some of the forked notes.
Quite a few of the surviving instruments have had their extra keys removed and the holes plugged. This is not really surprising, as the fairly primitive keys tended to be unreliable, and extra keys just got in the way. I owned a 13-keyed clarinet for some time, but parted with it in the end, preferring to play on a six-keyed instrument. This is why six-keyed clarinets were still being made in the 1840s. The most useful keys to have in addition to the basic five are C#/G#, B/F# and Eb/Bb.
Extra keys were mostly mounted on additional turned blocks. By this time all the blocks were carved away flush with the body except where they were needed to support the keys. Some keys were mounted in brass saddles which were held onto the body with small screws. The pads were made of flat leather and the seatings were also flat. The "cups" were of course flat as well and up until the 1820s were square in shape. After this date they were sometimes circular (but still flat). The keys were held in the blocks with brass pins which were just pushed through and acted as the pivot.
This is where I intend to stop my brief history of the early clarinet, as keywork developed very quickly after this and the first Boehm clarinets were being made by the 1850s. This huge progress in so few years became possible because of the increased reliability of keywork, due to rod and point screws, pillars, modern types of pads and cups and better materials.
I would just like to end with a few hints on playing the early clarinets. You cannot expect to pick up an early clarinet and play it the same way as a Boehm, as they take a while to become accustomed to. A soft reed is essential, otherwise the forked notes will be muffled. You also have to be prepared to adapt reeds; they usually need shortening at the stub end, and often need scraping. Cross-fingerings take a while to master unless you play the recorder, as it is difficult to raise one finger and lower another at the same time without a slight "double sound".
Modern phrasing sometimes does not suit old clarinets, and it is quite interesting to hear how subtle changes affect the music. One extreme example can be found in the Mozart concerto, which in its modern version has phrases that are impossible to play on classical clarinets. They are the phrases which have been transposed up an octave from the original basset clarinet part.
When playing on early clarinets, one quickly becomes aware of how technically demanding the music was at the time, and this should be remembered when you stroll through a classical work on your modern Boehm. Although the players of the time were obviously more familiar with their early clarinets, works like the Molter concertos become as difficult as many modern pieces, and imagine playing a Spohr concerto with only 10 primitive keys!
I would certainly recommend the playing of early clarinets as a rewarding and educational experience.