Whilst I would normally aim for as close to Zero deviation as possible, raher like Stephen Chamber's 0/+1, there is sometimes quite an amount of pitch change with pressure variation. I notice that instruments with longer scale reeds tend to be more pitch/pressure stable... a generalisiation perhaps.
When tuning to Equal Temperament a greater degree of accuracy is needed, because this tuning system only works tolerably well if all is equal however, where there is to be deviation from exact pitches due to the inevitable inaccuracies and pressure/pitch variances, then let them fall on the sweet side, if possible. As Greg Jowaisas suggests, don't let the major thirds get sharp.
What is meant by not letting this interval sit on the sharp side is that a Perfect major Third has 386 cents between the two notes and a Equal Tempered major Third has 400 cents. Better to have the ET thirds being not wider than the 400 cents and, if anything slightly narrower... at least in the most used Keys.
Might I suggest that for an accuracy Tuning Tolerance one could do this in E.T. :
Notes; A and D as close to Zero as possible. Bb,Eb , Ab = 0 / +2. C#,D# G# = 0/-2. B,E,F#= 0/-1. and G,F,C = 0/+1 . This should keep things leaning slightly towards the SWEET side.
The Major Third is a very harsh interval in Equal Temperament, especially on a Concertina, which is why I use a Meantone system on my Englishes. I've chosen to use 1/5th Comma Meantone ( Homogenous ) and whilst this is a halfway house compromise from the full 'perfect thirds' meantone (1/4 Comma) it still has notes that are quite widely spread away from Equal Temperament.... But I have yet to have another musician question the position of my notes, when playing in groups or sessions.
What I mean here is that if an instrument is 'in tune' with itself and is close to the Pitch standard ( in my case spread evenly around it) then other players will not think it out of tune.
When using the 'sweeter' tempéraments I think it is possible to have more tuning latitude..... I currently have two Concertinas tuned to Meantone and two that are Equal Tempered... it is always the ET instruments that I think need another 'fine tune'.
I own 7 different electronic Tuners ranging from the very inexpensive up to a Peterson 490 but in the end one's Ear and sense of touch are just as important.
When selecting a person to tune and set up your concertina it is best to find someone who plays your keyboard because it is only when you start driving the beast that you find the faults.
I recall my days living in Co Clare. and the Knock on the door of someone needing a quick fix or tune up... on their way to a gig or before their Examination the following day at Limerick University!
PS: to hear how the Homogenous Meantone sounds (and copes with Key changes) go to 'tune of the month' for May 2013, page 2... there you will get a link to my Soundcloud recording of the Playford tune 'Parson's Farewell' played in Seven keys... complete with plenty of mistakes
Edited by Geoff Wooff, 16 March 2014 - 07:28 AM.