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

[Sebastian Bravo]

I have a problem with this reed block... it has the same hole for both bass reeds.

So, i can't tune each reed with my tuning bellows... (I don't own the Dirk Accordion Tuner App, i just use Datuner for Android)

I had an idea of putting the reeds on another block, but that's a lot of work to tune each reed.

Any Suggestions? Just A and B are tuned...

 

[JerryPH]

Maybe some green or blue painters tape onthe inside/outside reed you don't want to resonate?

 

[Sebastian Bravo]

Maybe some green or blue painters tape onthe inside/outside reed you dont want to resonate?

Thanks for the tip Jerry, ill try tomorrow and post results.

 

[Morne]

I cant give you any tips from experience regarding the physical process. Obstructing the reeds from the outside might work, but youll still have some air leaking into the cavity. You could also consider building a little container that will let you test a single reed, but that would still require removing the reed.

So, i cant tune each reed with my tuning bellows... (I dont own the Dirk Accordion Tuner App, i just use Datuner for Android)

On the software side I would recommend you look at this app called Tuner which can detect multiple reeds/notes:
https://f-droid.org/en/packages/org.billthefarmer.tuner/

As far as I know its not on the Google app store. You can download the APK directly from that link or you can get it from the F-Droid app store (which contains only libre/open source apps). The Tuner app is written by Bill Farmer (a melodeon player, I believe). Ive been using F-Droid app store for 4 years and Ive had that Tuner app running (but only for single reeds) when I spent some time with the guy who worked on my accordions. So I can vouch for the safety of both that app store and the app itself.

 

[debra]

This tuner is a great find. I will check it out immediately (tuning an accordion right now).
Dirk's Accordion Tuner is of course the way to go on a windows pc. It can handle 2 different notes or 3 reeds of the same note but with tremolo.
Bass blocks that share a hole are not that common nowadays except in bayans which indeed do have them (because they have no registers to block one or the other reed. (Some do have a register to block out 2 of the 4 reeds that share the same hole.)
The blue painters tape method is not a great idea. When you block the airflow to one set of reeds it changes the airflow in the chamber and that causes a change in pitch. (Basically anything you do inside an accordion can potentially change the pitch of notes. For instance, taking one reed block out may throw off the pitch of the notes on the other reed blocks. No kidding!)

 

[debra]

Hmm.. I don't know what I'm doing wrong but nothing changes when I check the "show multiple notes" checkmark on my phone it shows it as being checked but when I go back to the tuner and again to settings it is unchecked again. On my tablet I managed the checkmark to stay on but it makes no difference... Maybe I'm doing something wrong or maybe this is still "future work"?

 

[Morne]

Ive noticed that checkbox behaving weirdly as well. You can turn multiple notes on/off by long pressing on the center block that normally displays the details for a single note.

For anyone else looking, heres the documentation: https://github.com/billthefarmer/tuner/wiki

 

[TomBR]

A finger on the other side of the reed block to hold the reed still and the valve shut? That's what I do.
That's about the smallest change you can have whilst stopping the other reed speaking.

Obviously where the reeds interact they can only do so when both are speaking, so you may have to tweak them individually to get them exactly as you want together.

 

[boxplayer4000]

Two Bass Reeds.
Interesting discussion here. I agree with TomBR’s approach while at the same time agreeing with Debra when he says that taping off or otherwise stopping one reed operating will change the air flow to the other and thereby alter the pitch. The biggest change to the pitch of one reed by stopping the other might well be because the reed that’s left playing will be getting will be getting all the air available; ie a change in pressure resulting in a change of pitch.
It might be easy here to get lost in the theoretical and forget that at low bass frequencies its going to take quite big difference of reed pitches to generate ‘beats’ as well as the fact that the lowest sounding reed will tend to ‘pull’ the other into resonance.
Maybe somebody with a good stroboscope can cast light on our theories.

 

[JerryPH]

I have no experience in real life, but I have a feeling that the difference will be negligible to all but the most discerning. I doubt it would make a 0.5 cent difference because of the added airflow... and if it did, just reduce airflow slightly to compensate... just my Canadian penny on this.

 

[debra]

Ive noticed that checkbox behaving weirdly as well. You can turn multiple notes on/off by long pressing on the center block that normally displays the details for a single note.

For anyone else looking, heres the documentation: https://github.com/billthefarmer/tuner/wiki

Thanks. That works on my phone at least. (It doesnt work on my tablet, maybe the android version is too old.)
But it doesnt work for multiple reeds of the same note, at least not for me. I check MH for instance and then press a note and very briefly a few octaves flash by but after just a second or so only the lowest of the two remains on the display. The higher note seems to be filtered out as just being a harmonic. (Of course, I am testing it now that the instrument is tuned.)
It does work with two different notes (not octaves).

 

[debra]

Two Bass Reeds.
Interesting discussion here. ...
It might be easy here to get lost in the theoretical and forget that at low bass frequencies its going to take quite big difference of reed pitches to generate ‘beats’ as well as the fact that the lowest sounding reed will tend to ‘pull’ the other into resonance...

Good point here. The tuning needs to be really very bad before you will hear a beat. Yet some people (like me) are bothered with even a slightly mistuned reed. Blocking one reed with your finger while measuring the other may throw off the playing reed by a few cents, but at these low frequencies that is almost nothing to worry about. The variation in frequency between the reed starting to play and going full blast will be much larger with bass reeds. (They tend to be very pressure-dependent.)
The best solution is still Dirks accordion tuner. This product exists for a reason... but for an amateur it is overkill. You need to tune many accordions to make it worth the price.

 

[TomBR]

Tuning aside, for octave tuned reeds I think you want to check with both speaking when adjusting the gapping of the lower one. The big reeds are quite sensitive at the best of times, and the higher reed acts as a "starter" for the lower one. When it's on its own I'll quite often give the lower reed a nudge to help it get started.

 

[Sebastian Bravo]

Bass blocks that share a hole are not that common nowadays

This Reed block is from a Hohner Arietta IM, a girl came to my house and asked for a complete tuning. (She dont know how to play the accordion and wants to start with a tuned one)

Its strange how the Concerto and Arietta models are the same box. But the Ariettas have that common bass hole. Quite annoying.

I think i will remove all the medium size bass reeds and tune them on another reed block. Its annoying because i already waxed them. I will have to re wax everything again...

 

[Morne]

I think i will remove all the medium size bass reeds and tune them on another reed block. Its annoying because i already waxed them. I will have to re wax everything again...

Have you considered making something like this single-reed container so that you dont have to wax the one set onto a separate block:
<YOUTUBE id=Bl8K8_TrI6c m=6 s=12 url=></YOUTUBE>

 

[Morne]

Ive noticed that checkbox behaving weirdly as well. You can turn multiple notes on/off by long pressing on the center block that normally displays the details for a single note.

For anyone else looking, heres the documentation: https://github.com/billthefarmer/tuner/wiki

Thanks. That works on my phone at least. (It doesnt work on my tablet, maybe the android version is too old.)
But it doesnt work for multiple reeds of the same note, at least not for me. I check MH for instance and then press a note and very briefly a few octaves flash by but after just a second or so only the lowest of the two remains on the display. The higher note seems to be filtered out as just being a harmonic. (Of course, I am testing it now that the instrument is tuned.)
It does work with two different notes (not octaves).

Ive actually only figured out the long press trick this week, so I havent tested the multi reed functionality much. But what Ive seen is similar to what you said. On my Morino, where the reeds are in tune, I had a hard time getting it to show same-note octaves.

On a different accordion where the reeds are not quite in tune, I managed to get it to show me all 3 notes for some LMM notes (I got something like L+3, M+5, M+8). The trick seems to be to touch the middle of the screen to freeze the information once the notes have stabilised. That will allow you to keep it on-screen. It seems like if you dont freeze the screen, it will keep only the most likely/correct note. However, this might be impractical depending on your setup and if you have any hands available.

So I would say that if the app does not pick up multiple notes then it might be okay to assume the notes are relatively well in tune. The last stretch will then have to be done by ear (or a better tool, but then you couldve probably used that from the beginning).

 

[Sebastian Bravo]

Have you considered making something like this single-reed container?

It looks very good but, does it change the pitch when i put the reed back on the reed block? and also, when i put the reed block inside of the accordion?

 

[TomBR]

I think i will remove all the medium size bass reeds and tune them on another reed block. Its annoying because i already waxed them. I will have to re wax everything again...

Why will you do this? :?

 

[debra]

Have you considered making something like this single-reed container?

It looks very good but, does it change the pitch when i put the reed back on the reed block? and also, when i put the reed block inside of the accordion?

A tuning table can be used to measure a difference: if a reed is say 4 cents too high when measured in the accordion, and when you put the reed block on the tuning table it shows 7 cents too high, then you can lower the reed down to 3 cents and when you then put the block back in the accordion it will be close to 0 cents off.
What you cannot reliably do is tune a reed so the deviation reeds 0 cents and then have it also be 0 cents off when you put the reed block in the instrument. Tuning would be a lot easier if this were the case, but alas... it may work on high notes that are not in cassotto, but it wont work for lower notes and it certainly wont work for lower notes in cassotto. It also often does not work on bass notes. The reasons for this is that the pallets do not open far enough to not add any resistance to the air flow.
In most cases when you put reed blocks in the accordion the tuning is pretty much the same whether the accordion is placed on its feet or in the playing orientation, and also whether the bellow pins are inserted or removed. Only with the very cramped bayans (russian or italian alike) does any of this have an influence. What I do instead of inserting the bellow pins is to tape the holes shut. (Careful that the accordion does not fall open.)

Common sense and good ears may help in circumstances where the tuning table and software is of little help, like with the non-removable lowest bayan reed block where no less than 4 reeds share the same hole! With the bass block with 2 reeds sharing a hole what you need to hear is whether the higher octave plays higher than the low octave or the other way around. Then you make a small adjustment and measure again, and repeat the process as often as needed until it is right. Trying to correct any tuning offset in one go often leads to overshooting the correction. Typically when I need to make an adjustment to a reed it takes 2 or 3 tries to get it right, and then another try the next day and sometimes another try again one day later. After 2 days the reed should be stable. (If it keeps deviating the valves are more likely the problem than the reeds.)

 

[MikeS]

What worked for me was a common eraser, cut to a little larger than the reed opening, with a sharp knife. held in place with my thumb while the fingers of the same hand are holding the block down to the tuning table.