Exploring bass register switches on my Morino converter Bayan

[breezybellows]

Had a long productive practice session yesterday. I'm also exploring the options I have with the free bass decoupler and registers on the left hand. This Hohner Morino Converter Bayan provides a bunch of different combinations for the free bass. L, LL, LM, LH and LMH. I'm playing the LL switch in this video.

 

[debra]

I never quite understood why they make such accordions with LL free bass. It tends to produce a nasal sound. The two L reeds (on opposite sides of the block) influence each others' tuning, so you cannot tune both the single L and then LL perfectly. It's not quite as bad as on Russian bayans (that use a single resonance chamber for both L reeds causing more tuning and also voicing problems) but it's a problem on all bass sides with LL configuration that I know of.
Also, you say there is an option to get LMH but I doubt that this is really true (for the higher octaves). Inside I expect that you have an LLH setup and while you can get LM and LMH on the lowest octave (where there is no LL but LM) you cannot get LM or LMH on the higher octaves, unless your accordion has a four voice higher-octave melody bass which I believe would require an even bigger box.
Anyway, best of luck practicing Mozart's 40th symphony. It is quite challenging. I won't even attempt that in a solo performance on my bayan, but I do have an ensemble version which uses 9 voices. (8 accordions plus bass accordion).

 

[breezybellows]

I never quite understood why they make such accordions with LL free bass. It tends to produce a nasal sound. The two L reeds (on opposite sides of the block) influence each others' tuning, so you cannot tune both the single L and then LL perfectly. It's not quite as bad as on Russian bayans (that use a single resonance chamber for both L reeds causing more tuning and also voicing problems) but it's a problem on all bass sides with LL configuration that I know of.

I haven't played it enough to fully experience the pros and cons of the LL option. For now, I see that in certain tonal ranges, the LL option makes the sound thicker without adding octaves. It's like a nice chorus. I haven't really played the LL on the left with the L on the right (definitely not on the same octave). So I haven't observed the problem with tuning yet. I have a question. Is the timing a challenge only when the LL bass and L the combination is engaged? It is it a problem that's always there in a accordion that has these blocks?

Also, I don't really understand what makes this interference any different from other accordions that have only L and H on the left. How does adding another unison tuned L block change the interference?

What I have observed though is some really unpleasant sounds when I play stradella with the MM on right hand. It makes a weird buzzy tremolo when the bass bottoms are played. Only one of the bass register switch is usable with the right have MM option. I haven't experienced this in the other transformer accordion I have.

Also, you say there is an option to get LMH but I doubt that this is really true (for the higher octaves). Inside I expect that you have an LLH setup and while you can get LM and LMH on the lowest octave (where there is no LL but LM) you cannot get LM or LMH on the higher octaves, unless your accordion has a four voice higher-octave melody bass which I believe would require an even bigger box.

Yes. You are correct. The H set is added using the bass coupler switch (located near the air button). So it will be available only for the notes that are lower than the highest available octave.

One more set of reeds will make this accordion to heavy. I haven't put this on the scale yet. When I carry this on my high bag, my shoulders feel significantly more weight than my Petosa Cathedral (which weights a solid 35 lbs). But the ergonomics are very good (thanks to the right shoulder strap mount behind the keyboard) when I play it. I've been playing this for 2-3 hours a session and the weight hasn't created any problems yet.

Just started on Mozart's 40th. I really look forward to making progress on that. Your ensemble arrangement was wonderful!

 

[debra]

In your recording you can clearly hear the nasal sound that is a result of using the LL register. You call it a "chorus". The problem is caused by the two L reeds not playing exactly the same frequency. It's close but the result is that there is this chorus where every so often the two base frequencies want to cancel each other out and that causes the harmonics to sound louder than the base frequency, and that's what I call the nasal sound.
With the right hand, using a dry-tuned MM register, you don't have that issue because one M is in cassotto and the other is not, and two effects come into play: the physical distance between the two M reeds is large enough for their airflow to not influence each other and the M in cassotto has less pronounced higher harmonics than the M outside the cassotto.
The other thing is the effect of the octave coupler(s): normally they just add a higher octave to the lowest 12 notes. But in the past Hohner has uas an octave coupler that worked on all notes except the highest octave. (That was in the Solist MB 2.) Maybe this one has that too, I don't know. It would explain how an accordion with LLH configuration can have a meaningful setting for 7 bass registers. (The second generation Pigini Sirius for instance offers just 5 registers and definitely has just an octave coupler for the lowest 12 notes.)

 

[breezybellows]

In your recording you can clearly hear the nasal sound that is a result of using the LL register. You call it a "chorus". The problem is caused by the two L reeds not playing exactly the same frequency. It's close but the result is that there is this chorus where every so often the two base frequencies want to cancel each other out and that causes the harmonics to sound louder than the base frequency, and that's what I call the nasal sound.
With the right hand, using a dry-tuned MM register, you don't have that issue because one M is in cassotto and the other is not, and two effects come into play: the physical distance between the two M reeds is large enough for their airflow to not influence each other and the M in cassotto has less pronounced higher harmonics than the M outside the cassotto.
The other thing is the effect of the octave coupler(s): normally they just add a higher octave to the lowest 12 notes. But in the past Hohner has uas an octave coupler that worked on all notes except the highest octave. (That was in the Solist MB 2.) Maybe this one has that too, I don't know. It would explain how an accordion with LLH configuration can have a meaningful setting for 7 bass registers. (The second generation Pigini Sirius for instance offers just 5 registers and definitely has just an octave coupler for the lowest 12 notes.)

Interesting. Should this be a problem on the treble side as well in instruments that have MM with no time chamber?

 

[Vladimir M.]

I personally have two voices (L and M) and three registers for their possible combinations in my free base accordion: L, LM and M, each with a range of 57 tones. What I appreciate most is the use of one single choir only in the free-bass along with a single choir in the treble (most often in the cassotto). In my opinion, adding additional voices often obscures the tonal clarity and originality of the work. Or vice versa: the "organoid" sound is often at the expense of the sound transparency of the work.

Building two tonally equal free-bass choirs (L and L) seems to me of little benefit, especially if one needs to switch between L and M during the playing due to achieve a higher tonal range.

Just my humble two cents opinion...

 

[debra]

Interesting. Should this be a problem on the treble side as well in instruments that have MM with no time chamber?

It can be a problem on the treble side when you have MM with no cassotto, when MM is completely dry-tuned and when both M reeds are on the same reed block. To avoid tuning issues due to resonance many accordions have a metal bridge fitted between (over) the reed blocks to reduce that resonance.
When I tune an accordion I first tune the single M, then the second M and then I check what happens when MM is played. Whether there is tremolo or whether the accordion is dry tuned, MM always has to be checked (and adjusted if needed) because the two M reeds influence each other. The tuning of the single M takes precedence, so of MM is then slightly off, so be it. The same holds for the LL on the bass: if you can select a single L (on a Russian bayan you cannot) that L is tuned first and then the LL is checked for being completely dry, not for having the right frequency (which is most likely does not).
Most other deviations are typically negligible: when you have LM any influence between L and M on tuning is negligible, and when tuning an accordion with convertor tuning is always done using the melody bass. Any deviation you may get when using Stradella (standard) bass is negligible.