How do I Tune Bass Reeds that share the same hole?

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Sebastian Bravo
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Re: How do I Tune Bass Reeds that share the same hole?

Post by Sebastian Bravo » Sun Jan 14, 2018 6:12 am

So... I did what i said. I put all the Arietta Bass reeds on my concerto III reed block (It has individual holes for the reeds)

This is the measure of the Bigger reeds inside the accordion (closed all the other blocks with masking tape on the bottom):

(O = Opening the bellows, C = Closing)

A) O: -10c C: -18c
A#) O: +1c C: -12c
B) O: -12c C: -35c
C) O: -36c C: B+42 (very detuned)
C#) O: -35c C: -30c
D) O: C+48c (very detuned) C: -35c
D#) O: D+44c (very detuned) C: D +48c (Very detuned)
E) O: -15c C: -30c
F) O: -11c C: -7c
F#) O: -10c C: -17c
G) O: -12c C: -37c
G#) O: -4c C: -22c

So i will tune these ones, then the other reeds. I will use the method that Paul De Bra mentioned, correcting the difference measured here.

Thanks to everyone for the support, please wish me success!

Last question: Will the tuning change when i move the reeds from the reed block with individual holes, to the original reed block with the big hole?
I'm Sebastian and i Play on a Hohner Concerto III called Modesto.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by debra » Sun Jan 14, 2018 8:30 am

These deviations are absolutely not normal. Do not ruin the reeds by attempting to just tune them!
When a reed is off by a lot in many cases the reeds themselves are not the problem but the valves are. The leather becomes stiff over the years and then the valves either do not open wide enough (note goes flat) or do not close properly (opposing note goes sharp). It is also possible for the valve on the inside to touch the end or sides of the reed block and then not open and close smoothly. So it is imperative that you do some good detective work trying to find sources of large deviations other than the reed itself!
The lowest reeds also have very pressure-dependent frequency. When it starts it may be 10 cents off from where it is after playing for 2 to 3 seconds. You then need to take some kind of average.
As to the question whether the tuning may change when you move the reeds back to the original block the answer is a very likely yes. Moving to a different resonance chamber can certainly influence the frequency.
The overall conclusion is: tuning bass reeds is hard and often unpredictable. (I wish I had a more positive message here...)
Paul De Bra (not Debra...)
http://www.de-bra.nl

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Sebastian Bravo » Sun Jan 14, 2018 8:18 pm

debra wrote:
Sun Jan 14, 2018 8:30 am
These deviations are absolutely not normal.
Yes, i thought the same.

I inspected the valves and they are in a good condition. The problem was with the reeds, they were covered with rust on the back part (the blue part of the reed) so i removed all the rust from all the reeds and got this strange tuning.

I will tune the "normal ones" and try to tune the very detuned reeds but very carefully, like 5 cents up, wait 5 minutes, then tune up again, trying to avoid overheatig the reeds and affect their tone.

I measured the last 3 sets of reeds and they seem to be normal (obviously detuned but no more than 15 cents) so i won't have problems with them.

I will post results in 5 hours!
I'm Sebastian and i Play on a Hohner Concerto III called Modesto.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by debra » Sun Jan 14, 2018 8:23 pm

Sebastian Bravo wrote:
Sun Jan 14, 2018 8:18 pm
debra wrote:
Sun Jan 14, 2018 8:30 am
These deviations are absolutely not normal.
...
I inspected the valves and they are in a good condition. The problem was with the reeds, they were covered with rust on the back part (the blue part of the reed) so i removed all the rust from all the reeds and got this strange tuning.
...
That the valves are in good condition is good news. That the reeds are rusted is not so good. Depending on where on the reed the rust is the frequency may indeed go up by quite a lot or down by quite a lot. In hindsight it would actually be better to have all reeds on the original block again so you can start making corrections and hear the effect on the pairs of reeds sounding together. Perhaps you should stop making corrections when you are no more than 5 cents off and then put the reeds back.
Paul De Bra (not Debra...)
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Re: How do I Tune Bass Reeds that share the same hole?

Post by Sebastian Bravo » Mon Jan 15, 2018 1:55 am

Depending on where on the reed the rust is the frequency may indeed go up by quite a lot or down by quite a lot.
The rust covered all the back blue part of almost all the biggerbass reeds (are those 16' or 32'?)

First i removed all the rust, then i got that tuning chart with very detuned reeds.

Today i tuned all the smaller reeds. And half of the big bass block (it is 4 reeds on the bass) i got all the notes on good tuning (almost +/- ~0.3c of detuning on all the reeds) so the bass is sounding really perfect.
I'm currently working on the bigger reeds but i have to eat something! So, i hope i finish with the basses tomorrow by the morning, it's 22:46 and i don't want my neighbours calling the police because of the reeds/dremel sound :lol: :lol: :lol:
I'm Sebastian and i Play on a Hohner Concerto III called Modesto.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Sebastian Bravo » Tue Jan 16, 2018 3:53 pm

https://www.youtube.com/watch?v=qLdUG6y1v7g

this is how it turned after first tuning... some notes are still out of tune, but it is getting better...

The girl asked it for monday so i had to give it to her... the accordion will be back in 5 days because she is going to a small town in the south just to practice on the wild side... she doesn't know how to play basses so she didn't care that much.

D big bass reed is still D - 35 after a lot of work (It was C# +44 before work) but i had no time to tune it better.
I'm Sebastian and i Play on a Hohner Concerto III called Modesto.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Geronimo » Tue Jan 16, 2018 5:09 pm

Sebastian Bravo wrote:
Tue Jan 16, 2018 3:53 pm
D big bass reed is still D - 35 after a lot of work (It was C# +44 before work) but i had no time to tune it better.
Have you cleaned it thoroughly from rust (using a glass fiber pen and/or some oil which you need to completely remove afterwards)?

If you did, then with that amount of material rusted away from the weakest point of the bass reed, this one is likely to break at some point of time. I mean, right now you can probably mostly file from the weight, but you'll have a misfit between reed profile and weight afterwards which is bad for pitch stability under pressure.

If you did not, do that first thing before any more tuning on it.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Sebastian Bravo » Tue Jan 16, 2018 6:48 pm

Geronimo wrote:
Tue Jan 16, 2018 5:09 pm
Sebastian Bravo wrote:
Tue Jan 16, 2018 3:53 pm
D big bass reed is still D - 35 after a lot of work (It was C# +44 before work) but i had no time to tune it better.
Have you cleaned it thoroughly from rust (using a glass fiber pen and/or some oil which you need to completely remove afterwards)?

If you did, then with that amount of material rusted away from the weakest point of the bass reed, this one is likely to break at some point of time. I mean, right now you can probably mostly file from the weight, but you'll have a misfit between reed profile and weight afterwards which is bad for pitch stability under pressure.

If you did not, do that first thing before any more tuning on it.

Thanks for the tip Geronimo, i think what you say is probably the problem. Because i removed a lot of mass from the reed and i couldn't get it to perfect tuning. Maybe another reed would do the job.
I'm Sebastian and i Play on a Hohner Concerto III called Modesto.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Edocaster » Fri Jan 26, 2018 8:09 am

Must be a Hohner thing. I have the same shared hole thing with a pre-war Verdi (plus that was glued in :roll: ).

Tape won't help, as they share more than just a hole, more like a quarter the chamber.

Trying to silence one reed will affect the tuning of the other, I believe.

What I found worked was recording the sound in audacity or audition) and using frequency analysis to see the two peaks.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Geronimo » Fri Jan 26, 2018 9:11 am

Edocaster wrote:
Fri Jan 26, 2018 8:09 am
Must be a Hohner thing. I have the same shared hole thing with a pre-war Verdi (plus that was glued in :roll: ).

Tape won't help, as they share more than just a hole, more like a quarter the chamber.

Trying to silence one reed will affect the tuning of the other, I believe.

What I found worked was recording the sound in audacity or audition) and using frequency analysis to see the two peaks.
Well, FFT does not work well for that: a time window of 1s gives you just 1Hz of resolution. Stroboscopic tuners are one possibility: you use eye sight to lock onto the period of the respective frequencies. Using visuals for discriminating between various rather constant frequencies and their overtones and noise works reasonably well. LPC analysis might also work but is more sensitive to noise and overtones.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Edocaster » Sat Jan 27, 2018 10:51 am

Geronimo wrote:
Fri Jan 26, 2018 9:11 am
Edocaster wrote:
Fri Jan 26, 2018 8:09 am
Must be a Hohner thing. I have the same shared hole thing with a pre-war Verdi (plus that was glued in :roll: ).

Tape won't help, as they share more than just a hole, more like a quarter the chamber.

Trying to silence one reed will affect the tuning of the other, I believe.

What I found worked was recording the sound in audacity or audition) and using frequency analysis to see the two peaks.
Well, FFT does not work well for that: a time window of 1s gives you just 1Hz of resolution. Stroboscopic tuners are one possibility: you use eye sight to lock onto the period of the respective frequencies. Using visuals for discriminating between various rather constant frequencies and their overtones and noise works reasonably well. LPC analysis might also work but is more sensitive to noise and overtones.
I'm not an expert on FFT, but I've found the results more than acceptable. Playing steady notes for two seconds duration, the readings are accurate enough to show differences between push and pull that I can't really hear. Set an FFT size of 65536 (the highest on most software), and for a 48khz sample rate that will use up most of the two seconds.

This is what you see on Audition:
freqanalysis-graph.jpg
The choice of window function can help how the data is represented. 'Hamming' in this case gives a nice visible peak.

Audition will also let you see the underlying data - i.e. the amplitude at each frequency. In the example above each reading is 0.732Hz apart (48000/65536). But you can easily interpolate from the available values to work out the location of the peak just by looking at three or four values on either side. I reckon 0.25-0.5Hz accuracy is quite possible.

Counter-intuitively, dropping the sample rate to 24khz would also increase the frequency resolution, although then the note would have to be played for over three seconds (I wonder if looping the note would achieve the same result?).

Finally, as this tuning method is only used when two octaves are played together, the best approach would be to use the better available accuracy on the higher octave bass note, and then finally correct the lower octave bass note by listening for beats.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Geronimo » Sat Jan 27, 2018 11:19 am

Edocaster wrote:
Sat Jan 27, 2018 10:51 am
Counter-intuitively, dropping the sample rate to 24khz would also increase the frequency resolution, although then the note would have to be played for over three seconds (I wonder if looping the note would achieve the same result?).
Looping the note would achieve the same result if you looped after an exact length of the note's period. To do that, you'd need to know the exact length of the note's period, and if you knew that, you'd already be finished. So yes, it would work if you did it right, but to do it right, you'd already need to know the end result.
Finally, as this tuning method is only used when two octaves are played together, the best approach would be to use the better available accuracy on the higher octave bass note, and then finally correct the lower octave bass note by listening for beats.
Accordion tuners (and organ tuners, the people, not gadgets) basically do everything by laying down a central reference octave first, tuning it in fifths tempered with the correct beat frequencies. Then they tune everything to be without beats with regard to the reference octave. That way, the tuning accuracy is invested where one can hear it. Any tuning method working with absolute pitches needs to be done doubly as exact for the same audible accuracy since then the tuning errors for both ends of hearing-critical intervals are independent.

Tremolo tuning is an additional complication.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Sebastian Bravo » Fri Feb 09, 2018 6:57 am

Edocaster wrote:
Fri Jan 26, 2018 8:09 am
What I found worked was recording the sound in audacity or audition) and using frequency analysis to see the two peaks.
I will try to use that method tomorrow, with a a Hohner Contessa II that came recently for a full restoration (rust removal, cleaning, new valves, wax and tuning)

https://youtu.be/9qg4LC8XPjg
The girl came back from her vacation and got me her accordion for the final tuning. I recorded this video days ago and forgot to upload it, it sounds really better now.

Thanks everyone for the support, suggestions and everything. I wil make the D.I.Y. accordion microphones tutorial in some days!
I'm Sebastian and i Play on a Hohner Concerto III called Modesto.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Morne » Wed Feb 14, 2018 8:21 am

Sebastian Bravo wrote:
Fri Feb 09, 2018 6:57 am
https://youtu.be/9qg4LC8XPjg
The girl came back from her vacation and got me her accordion for the final tuning. I recorded this video days ago and forgot to upload it, it sounds really better now.
Well done. That is indeed much better.
How much did the tuning change going from the Arietta block to the Concerto block and back again?
And how did you measure the final tuning inside the accordion? Did you block the reeds somehow, or did you tune by ear?

With the shared hole, glued-in block I'm working on now, I find myself weaving a wide strip of paper over the valves and under the reeds in order to silence the one side. Now this probably affects the pressure to some degree since the one side is now no longer releasing air properly. But that's as close as I'll get until I figure out a trick I have in mind with the Tuner app I use.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Sebastian Bravo » Wed Feb 14, 2018 5:31 pm

Morne wrote:
Wed Feb 14, 2018 8:21 am
Well done. That is indeed much better.
How much did the tuning change going from the Arietta block to the Concerto block and back again?
It was Ok, just 1 or 2 cents changed, to correct them i removed one of the reeds and put a piece of wood on it's place, so i could play just one note. Then the same with the other reed. Got a perfect tuning. I used this chart from a russian forum, to get a "bassier" sound:
bas33.png
bas33.png (162.73 KiB) Viewed 444 times
The tuning is OK, treble side is 5hz tremolo on the first notes, then 4hz on the middle, 3hz on the higher notes.

The girl is very happy with her accordion now because it had a really big change. I did all the tuning, valves and wax process in 2 weeks, i think i got this one pretty quick.

Try using Dirk's Accordion tuner Trial version. It has some notes missing for tuning, but it will work on most notes correctly to tune in octaves perfectly. For the missing notes on the App, use your method.
I'm Sebastian and i Play on a Hohner Concerto III called Modesto.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Morne » Thu Feb 15, 2018 10:35 am

Sebastian Bravo wrote:
Wed Feb 14, 2018 5:31 pm
I used this chart from a russian forum, to get a "bassier" sound:

bas33.png
While I can make sense of the Russian on the chart, I am not 100% sure if I am interpreting it correctly. Are they saying for a 4 reed bass you would (de)tune the reeds as follows:
- low bass +4
- high bass +2
- low chords -2
- high chords +0

Actually, if you still have the link where you got it from, I would like to have a look at it.

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Re: How do I Tune Bass Reeds that share the same hole?

Post by Sebastian Bravo » Thu Feb 15, 2018 7:09 pm

Morne wrote:
Thu Feb 15, 2018 10:35 am

- low bass +4 cents
- high bass +2 cents
- low chords -2 cents
- high chords +0 cents

Actually, if you still have the link where you got it from, I would like to have a look at it.

It is correct Morne, try that tuning!

http://forum.mirbajana.com/viewtopic.php?f=10&t=36

This is where i got that tuning chart. There are other 3 versions of it.
I'm Sebastian and i Play on a Hohner Concerto III called Modesto.

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