Why are octaves not good to end a phrase on in a Minuet?

I have gotten this response from some people giving feedback on my Minuet in Bb:

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The octaves at the end of the first phrase and the whole piece lose some weight, where a different harmony could have been more effective.

I addressed why I ended the phrase and the piece in octaves, but got no response back on this forum, so I thought I would address it here. Here was my reasoning behind ending it in octaves:

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Well, I wanted to make sure it sounded closed at the end of the A section and at the end of the piece, and I was doing 2 voice counterpoint, so I had it end in octaves for that reason(in my mind, the octave is the most closed of cadential intervals, especially when preceded by a leap in the bass). Also for that reason, I had the bass leap from F to Bb in the final cadence of both the A section and the piece.

Here is the A section of my Minuet with the structure highlighted:

As you can see, it is structured as a question and answer type of phrasing. The first cadence at measure 4 is open, it poses a question, because, while yes, it is a Bb major harmony, it ends on an interval of a fifth, and fifths give a sense of openness. Also, the diminuendo combined with the left hand arpeggiation further adds to that questioning feel. The fifth poses a question which is then answered by the consequent phrase. The second cadence at measure 8 closes off the section. It ends in octaves, and as I said in the previous quote, I think of octaves as being the most closed of cadential intervals, especially when preceded by a leap in the bass as it is in measure 8. The loud dynamic further reinforces that closing off of the A section. 

However, when I adressed this reasoning to more people, they weren't on my side of the argument at all. They also thought that a different harmony would be more effective at measure 8.

So now, I'm a bit confused. Octaves are the most closed of cadential intervals and yet aren't effective in the ending cadence of a section of a Minuet? How can that be? In a lot of works from Haydn onwards and even works by Bach, having a closed cadence end in octaves is not only common, it's the norm. From Beethoven onwards, octaves become the norm in all circumstances, be it tremolo like in a lot of Beethoven's own works, or leap like in those of Chopin and Liszt. So how is it that octaves are the norm in closed cadences, yet my own closed cadence in the A section of my Minuet is not effective, even though it ends in octaves?

Hi

What you hav there in the end of the Phrase A' is not a perfect authentic cadence in terms of baroque-classicism.

The authentic perfect cadence is this:

1. Harmonic movement V - I. 

2. The bass must be the fundamentals and move an ascending 4th or descending 5th. And the conclusion has to be in strong position. 

3. Melody moves the leading tone to the tonic.

In this case n.2 and n.3 are not written. OK, take the F in the bass in first part of next to las measure as the strong note (is the first in the measure)..... The Bb in the bass should be also in the firt pulse of the last measure, not in the third.

The melody doesn't go from leading tone to tonic.

That's the authentic perfect cadence, usually reserved for the finals of sections, movements, etc....

At least that's how I was taught. OK, you can call it whatever you want, but any cadence that goes out of those "rules" is weaker.

On the other hand, octaves (and unison)  is the weakest interval in counterpoint. If you have several octaves one after the other, your are not making harmony. That's why parallel octaves were avoided in counterpoint (the same happens with fiths).

In the other cadence, happening before, there are parallel sevenths, which was considered dissonant.

I don't know exactly what it means open and close authentic cadence ¿? Do you mean imperfec and perfect authentic cadences ?

6 minutes ago, Luis Hernández said:

In this case n.2 and n.3 are not written. OK, take the F in the bass in first part of next to las measure as the strong note (is the first in the measure)..... The Bb in the bass shoul be also in the firt pulse of the last measure, not in the third.

This is the main reason. The bass sounds like it's doing a typical V6/4 - 5/3 - I motion (or V8-7 - I), while the soprano sounds like a prolongation of tonic scale degree 1. Sounds like you're trying to have it both ways.

This is an interesting post - I will have a listen to this later and look to make some recommendations. On first glance I find it unusual for you to cadence with a Ic chord (F in the bass) whilst not considering modulation to the dominant. You could certainly consider an upward moving bass to the F, whilst a falling upper voice to an A natural. This would constitute a converging cadence to the dominant. In addition, your harmony in bar 3 is unusual, as I am unsure why you have opted for paralell sevenths between the bass and upper part. 

Though as I said I will revert. 

I have written some variations on your theme, to help organize your ideas more coherently. It is very important to clearly define your bassline as much as your upper voice. The cadences should be the most straightforward part, especially if we are working with two parts.  Any questions feel free to continue on this thread, or by private message.

You can see that in the first and second variations, the music modulates towards the dominant just before where would be the end of the A section. This is in line with the direction of many, dare I say, thousands of minuets composed during the 18th century. The B Section would typically begin with a Fonte, or a Minor to Major 4 bar passage (to modulate to the Major one would simply lower the previous 2 bar phrase by a step). Followed would be a phrase leading to a cadential flourish towards the Tonic.

There are of course endless possibilities within such apparatus', however the greater deviance from norms and the less definition, so to speak, in the overall direction, renders the minuet less fit for purpose as a dance. Composers such as Mozart and Haydn took the idea of a minuet and expanded its structure to the point where it was no longer intended to accompany a dance, so to speak. However, the underlying bass and its relationship with the upper voice was at least predictable to an extent thus retaining many of the characteristics and formula established long ago.