You have probably read the page which talks about the notes that are sounded when we press a particular button on the diminished 7th row (The Mystery of the Diminished Row) and are now wondering how diminished (or diminished 7th) chords are used in a musical setting.
There are 2 very common uses of the diminished chord so I will concentrate on them;
We play the appropriate chord by looking at the starting chord and the chord that comes after the diminished chord to decide which diminished row chord button to press.
In the first case above, the sounds may last for a period - perhaps seconds. Here you might consider putting much of the chord in the right had and using anything on the bass side that fits.
On the other hand, if the sound you want is short-lived I usually use the diminished chord note in the row of the named bass note (although I know that this is not really the chord requested).
In the second case above, I usually use the counter bass row. In the example above, I would play a C bass followed by a C major chord. I would then play an A counter bass (that is, a C# bass note) with the diminished row button in the E bass row. Then I would play a D bass note and then a D minor chord. The E diminished chord button will sound E, G and C# (it doesn't play the B flat more >>) which is, of course, C# diminished. There is one additional note here; I use my thumb (finger 1) to play this diminished button. Some people think this is an unacceptable practice.
The fingering described here should help you make sense of how to play bar 3 in Set 2 on the Bass runs and fills page.
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