A Problem With Harmonics

[Michael Marino]

I own a 20 Keys lachnel Brass reeded concertina. I have restored as much as currently possible on the budget I have and am in the process of getting the money together to put new bellows on it (thank you mister Tedrow for that wonder video that will help with the assembly of the new bellows).

 

The item that Have come across in doing fine tuning on it is that you get multiple harmonics off of a reed and at times the secondaries show up as stronger than the primary that I want. Now this is not just a problem with my concertina. When tuning my wifes Violin I need to at times tune to the key wanted instead of the key the mic is picking up with the key wanted.

 

I am using TuneIt 3.43. Which as long as I calibrate it against the sound card before using it each time (I turn my computer off when not in use as they eat a good bit of current) I brring the computer up and the program up to tune something I get very good tuning out of it. Will be improving the sound in the future but tested independently with a concert tuner my tuning is with 3 to 4 cents and i tune to +/- 1.5 cents when possible (the concertina I tune to 3 cents as pressure changes cause a bit to much havoc at present, hopefully new bellows will fix part of that).

 

My question in this is there any way known to reduce/remove the secondary harmonics of the reeds by shaping and if so what are they? I realize that it is possible in theory, what I want to know is it possible practically. The concertina is a wonderful instrument and I am very much enjoying playing it and learning about it. Only the more I learn the more i am wondering how to refine the notes to a pure form with which to produce even better quality sound with. Yes I know that that 20 key Lachnel is a bottom of th barrel for its time concertina but the brass reeds sound wonderful and really need to get the new bellows to give a much more even pressure to it so that I can get even sound production across the movement (yes I work very hard to keep pressure even and speed even when tuning and when playing songs that require it).

 

Thanks already to Chris Algar for the information he has given and also to David Leese for his work and aid in getting the one I have right now up and playing.

 

So any discussion on the above question and pointers on possibilities would be greatly helpful. For tools I have a Jewelers loop #2.5 a set of jewelers files and a flex shaft tool similar to a dremel and a good selection of bits.

 

Again thanks for any information or ideas. NO I don't want to retune it to steel reeds that is my next project after this is fully working is either a steel reed Hohner 30 key Anglo or building a 36 key Anglo myself (using Czech reeds)

 

Michael

Edited September 10, 2007 by Michael Marino

[Robin Madge]

A friend of mine has been recording and analysing concertinas note by note using the audacity program for some time (about 20 so far) and quite often you see a spike of a harmonic that is higher than the "note" of the reed, but it is usually a narrow spike.

The interesting thing to my perception of the sound is that the overall instrument sound seems to be most affected by what's going on at lower frequencies thatn the "note". If you have a higher level of sound at muliple lower frequencies the sound is more mellow. I look at the size of the "hump" on the left of the graph.

 

Robin Madge

[David Barnert]

The item that Have come across in doing fine tuning on it is that you get multiple harmonics off of a reed and at times the secondaries show up as stronger than the primary that I want. Now this is not just a problem with my concertina. When tuning my wifes Violin I need to at times tune to the key wanted instead of the key the mic is picking up with the key wanted.

Are you complaining about how the instrument sounds, or how the sound is represented by an electronic tuner? If it sounds OK, then I wouldn't mess with the harmonics, because you never know how that will affect the sound. Sounds to me, since you're also having trouble tuning the violin, that the problem has more to do with the tuner (or what's expected of it) than the reeds.

[Johann]

TuneIt 3.43. should not be the problem of not beeing able to tune to the fundameatl.

It works quite well for fast jobs.

 

It is usal that some low reeds produce stronger harmonics, depends a lot on the construction of the chamber and the reed.

Yes one can change this by making new reed tongues and or chambers. But dont do it!

[Dana Johnson]

The harmonic content of a concertina is what gives it it's sound character. a good tuner will lock on and tune the fundamental ( or in the case of a piano or other specialized tuner)or will listen only for the pitch you want to tune. If you try for a purer sound you will end up with a concertiha that is trying to be a flute. ( generallly close to sine wave ) Tunit should show the fundamental, and if it is doing that, it doesn't matter for tuning purposes what the other harmonics are. If you notice it is starting an octave high or a fifth or some other interval indicating that it is not picking up the fundamental, then you need to change your mic position until you get the low note strong enough to register. Cheap electronic tuners can't deal with this and only go for the loudest pitch, but Tunit shouldn't have that problem. It is normal and natural for even the best concertinas to have strong harmonics.

 

If you are a maker and going for a specific sound, think about your reed profiles ( and the rest of the intrument which has a big effect on the timbre ) but for a casual tuning, leave the reeds alone as far as their profile goes and get some pretty good advice on the tuning process before you wreck the reeds you have.

Dana

Edited September 10, 2007 by Dana Johnson

[ragtimer]

The harmonic content of a concertina is what gives it it's sound character. a good tuner will lock on and tune the fundamental ( or in the case of a piano or other specialized tuner)or will listen only for the pitch you want to tune. If you try for a purer sound you will end up with a concertiha that is trying to be a flute. ( generallly close to sine wave )

 

It is normal and natural for even the best concertinas to have strong harmonics.

 

Dana

Dana is right. You dont' want to sacrifice the characteristic rich tone of the concertina jsut to make it easier to tune electronically! You only need to tune it once, but you hope to play it for years.

 

I doubt your wife would approve of stuffing rags into her violin to make the sound more "flutey" and easier to tune :-)

 

May I suggest using a stroboscopic tuner? Either a genuine mechanical strobe such as were found in school band rooms a decade ago, or a software simulation or a box with a pattern of LEDs? You want one that can be set to a given note (like B-flat), and then you tune for a stationary pattern.

 

Or, you could patch an audio low-pass filter between your mike and the PC tunign program, and adjust it to allow only the fundamental pitch to get thru. Not sure where you would find such a gadget outside of a laboratory, though. --Mike K.

Edited September 11, 2007 by ragtimer

[Michael Marino]

Thanks for the advise will take it in and see how goes. Here are some points I am looking at before doing anything to reed profiles:

 

1) Buying a better sound card as the one I have varies from -12 cents to +6 cents when TuneIt does auto calibrate (I do this every time that I set about tuning an instrument since I don't leave the computer on and temp' does make a difference).

 

2) Buying a better Microphone to get a good bit better pick up as moving the Mic' does change which note is being picked up and that is with any of the instruments we play not only those that can be/are tuned.

 

Since I know of a few professional who swear by TuneIt with the right Mic' and sound card that leaves only a few loose ends to get things better and more accurate in sound. As i plan on playing this both at church and also with other musicians in public the tuning is very important. With that said it seems the secondaries are wanted as long as they are not discordant or strong to the ear than the desired note. Basically a case of impurity creating purity. Not a problem as it part of the analog/digital/Live argument and i know which side of that one I am on.

 

This also helps with some of the other design work that i am doing so thanks twice.

 

Also does any know what the accidental keys are on a Hohner (German, notice 2 H's) 30 key anglo and the key structure on their English as the website doesn't say.

 

Michael