Objective Specifications

[ttonon]

I meant for this comment to be included in the thread on the Elise, but after composing it, I found that that thread got locked. Can someone explain the lock?

Maybe we should just start a thread comparing instrument performance data. Factors like air consumption, maximum reed amplitude, air flow economy/reed coasting, harmonics produced, pitch stability, equilibrium, key pressure, key travel, etc.. This is how instruments are normally compared, just like cars and other products: you compare measurable facts, not opinions. I am not going to start something like this, but if someone else does, I will be more than happy to include all our instruments, both with accordion and traditional reeds.

Hi Wim. This is a verrry interesting comment. I for one would be most interested in seeing a discussion involving such “measurable facts.” But before we need even start such a thread with actual data, let’s see how far we can get in simply defining the following parameters in terms of other, measurable quantities:

1) Air consumption

2) Maximum reed amplitude

3) Air flow economy

4) Reed coasting

5) Harmonics

6) Pitch stability

7) Equilibrium

8) Key pressure (force)

9) Key travel

Wim, I’m not sure how far along you are in this issue, but I think some of these quantities are much better defined than others. For instance, (1) can be measured by pressurizing the bellows to a standardized level (say 5” water column), then measuring the air flow required to maintain constant bellows pressure while a key to a specific reed is totally depressed. Thus, for each key, a particular “Air Consumption” value would be specified.

 

(2) Maximum Reed Amplitude could be defined by placing a test reed on a cavity made with standardized geometry, then delivering air to the cavity by a standardized air delivery system, with a corresponding measurement of the vibration amplitude of the very tip of the reed, which can be done by eye using a simple machinist’s scale, or even by a more sophisticated, yet still simple, scale.

 

(3) Air Flow Economy. Wim, here, I’m not sure how you would define this quantity. I see competing definitions, but I’d think that the best definitions would involve audio output. However, sound measurements introduce a tremendous complexity, thus, a simpler and more practical definition might include, in place of a sound measurement, a measurement of pressure drop across the reed. But we already have such a parameter in (1). Can you elaborate further?

 

(4) Reed Coasting. I’m not sure what you mean here, but I think this parameter might consider the transient vibration of the reed tongue that persists and finally dies out after the delta P across the reed is removed. How do you quantify this parameter? What value do you see in it? Can this parameter be changed without changing other, perhaps more important, reed parameters?

 

(5) Harmonics. Measurement and evaluation of harmonics can possibly lead to great confusion, though there might be something useful here. If so, then perhaps the criteria by which a definition is made must ultimately rely on subjective reactions. For me, I might for my own purposes look at amplitude ratios between different overtones, with respect to the fundamental, because I myself am averse to higher harmonics, and I see possibly an advantage to have the lowest overtones dominate. Can you reveal to us your own criteria here?

 

(6) Pitch Stability. Although I’m not sure, you may mean that pitch stability is the ability to maintain a constant pitch of musical tone as the delta P across the reed is increased. I’m sure we’re all aware that the free reed tends to flatten in pitch above a certain maximum pressure drop. In this case, a useful definition of Pitch Stability might be the ratio of pitches, or the percent drop in pitch when two standardized pressure drops are imposed – one at typical playing pressure, and the other at the largest expected to be encountered during actual performance.

 

(7) Equilibrium. I don’t understand what you mean here. Please explain.

 

(8) Key Pressure (force). I think this parameter has already been used now and then in the literature and on this forum, and I’d define it as simply the total force it takes to depress a key the maximum amount.

 

(9) Key Travel. Again, this parameter is relatively simple and is already in use.

 

Wim, do you mean to say that you have these nine parameters in numerical form as a way to quantify the performance of all of the instrument models you sell? Do you include them with purchase of the instrument? If so, I’m impressed. I think it would be a significant addition to the trade if such parameters – and perhaps others - could be adequately and rigorously defined, as a way to compare instruments – not only those between different makers, but also those by the same maker.

 

Can you please explain what "ampliphonicly" means?

 

Best regards,

Tom

www.bluesbox.biz

[Ransom]

I meant for this comment to be included in the thread on the Elise, but after composing it, I found that that thread got locked. Can someone explain the lock?

 

I'm sure it's because we all started accusing each other of being racist instead of talking about concertinas.

 

(7) Equilibrium. I don’t understand what you mean here. Please explain.

 

I think I know this one, too: the volume balance between the higher- and lower-pitched reeds. If you play a high note together with a low one, the low one tends to drown out the high one unless you've got good equilibrium.

 

Can you please explain what "ampliphonicly" means?

 

I took that to refer to the "pan"-style mounting traditional for concertinas, instead of the "block"-style mounting typical of accordions.

[Ardie]

Replacing the action does not have any effect on sound quality, only key pressure and action noise. You can only improve these parameters by installing a heavier (brass) action. Improvement will be around 10-15 grams of key pressure reduction. Noise reduction is too small to measure.

 

Wim, can you please explain: How the key pressure may be reduced by a "heavier" action ? How 10-15 grams reduction of key pressure may be achieved? You first say that replacing the action has an effect on action noise - and later "Noise reduction is too small to measure". How do you mean?

 

Reed quality classes relate to air flow resistant and harmonics they produce. Low end reeds produce less harmonics (less bright) and need a higher air flow value because of energy efficiency and reed resistance.

 

I am trying to understand this.Do you *generally* mean that

1) Low end (= lower quality?) reeds *both*

- are less efficient

- produce less harmonics and thus sound "rounder"

2) High end (= higher quality?) reeds *both*

- are more efficient

- produce more harmonics and thus sound "brighter"

 

or is there another category

3) high end (=higher quality) efficient reeds which do not sound harsh/bright?

If so - how are they designed? Does the frame venting have influence on the harmonic spectrum? Does the tongue tapering have influence on the harmonics?

 

Example: If you want an instrument to sound round, not harsh/bright, and the air flow value is 75, you can easily use reeds that need a 50 flow value and produce less harmonics...

 

But do these (more efficient) reeds not according to 1) and 2) above produce more harmonics? Or do you refer to another type of reeds according to 3) above ?