Ισοκράτημα Δεύτερου Ήχου / Isokratema of Second Mode
Can ison be BOY sometimes?
Questions and Answers
What should the isokratema be in Second mode, especially in temporary endings on BOY?
Here are some recordings that demonstrate the case in question. A detailed analysis of each of them is pending.
From the Pasapnoaria of Second mode:
Emmanouilidis-Isokratema-BOY.mp3
Ierodiakonou-Ison-BOY.mp3

Notice how Taliadoros/Karakasis have changed the classical cadence
Taliadoros-Isokratema-DI.mp3
Karakasis-Ison-DI.mp3

From other recordings:
Asteris-Ison-DI-end-BOY.mp3
Maistores-Ison-DI.mp3
Batopedinoi-Ison-DI.mp3
Firfiris-Ison-DI.mp3

Notice the continuously moving ison of Vasilikos' choir
Vasilikos-Ison-BOY.mp3

Discussion on Typikon and ByzantineChant forums:
G. K. Michalakis:
Ths ison, according to Tsolakidis, and concerning the children, was DI for everything of the above (2nd mode Di, Second mode Vou, Pl. 2nd heirmologic bou, even fourth mode Di). The same goes for Katavasiai of 6 Jan: The Pa of the "hard chromatic" heirmologic 2nd is considered as the Di of th "soft chromatic" heirmologic 2nd. Now, there are those that "soften" the "hard chromatic heirmologic" tetrachord, and in the canon of the Holy Monday provided in Constantinos Doxastarion, the lines he provides make this easier. I've tried to "mix" a bit these intervals in the "Kalophonikos Heirmos " of 2nd mode "hard chromatic" fthora I sent you (for instance, Ga is not always closse to Di, an Bou isn't always close to Pa. If I were singing a True Pl 2nd, I'd do my best ot keep Ga up, regardless of the way the melody progresses (now, there is a whole debate about the functuation of this Ga: but my opinion is that it should be lowered only when the fthora of plagal 2 is used in 2, whereas as it should barely move in Pl 2nd.) Now, some Arabs do an isson on Ni for pl2nd BOU. It doesn't sound bad.... I don't know where they hold that from. Elie Khoury did have a Greek clergyman as a teacher... So, I don't know...
D. Koubaroulis:
Ok, but would you (I mean Tsolakidis) follow melos at the end of "H Asomatos Fysis" for example or keep DI throughout the piece? Would you follow melos at the long cadences to BOY in the slow "Agapesw Se"?
G. K. Michalakis:
That's a very good question. The children who were beginners would continue to keep Di throughout. The first Canonarch was a "partial domestichos", just as some of the adult isokrates, the isokrate being all as well divided into two groups: those who knew and those who were beginners. Beginners would keep isson an octave lower than the melody. Otherwise, they would be on the melody line, but where the "initiated" ones would follow the melody, the "beginners" would fade out (lower the volume) so a not to intefere. As I was saying, the first canorch was an "initiated one". He therefore had authorisation to be a "partial domestichos (a true domestichos would sing along from a to Z, except maybe parts of "Triadi", or parts of "Doxa soi of the Evangelical reading), which means he would sing along just before the martyriai (partial , complete and total catalixeis), which Tsolakides resumed in the phrase "o canoa=narchos ito pragmatikos psaltis. Gnorize olo to mathima ek stithous. Ochi monon canonarchouse, alla synepsalle kai eis ++++olas tas katalixeis++++(The First canonarche was a true Psaltis. He knew the chanted lessons in full and by heart. Not only did he precede the chantor by calling out rapidly what was to be chanted, but he would sing along ++++all the conclusive musical lines++++. So, the First canonarche and the isokrates (non initiated group) had differnt isokratima functions. Let's take the "I Asomatos fysis".

I A so ma tos fy sis ta Che rou bim
1can: DI...................................
IsonB DI..................................
a si gi tois se hYm nois do xo lo gei
1can: DI...............MELOS.............DI.
IsonB Di...........lowervolume.......Normal

For Agapiso se, I don't have a direct answer. But I suppose it would be the same as Epinikios hYmnos (Sanctus) of Meg. Basil. . The question is, what happens during modulations (fthora) in that peiece. I don't know, because he was kind enough to let me explore various isson. So i did what is current use. If ever I did "too much", however, he'd let me know, so "explore" did not mean just about anything. But I won't give you facts that are not from his sayings. But for the chants of Holy big Tessarakosti, I know so, because he told me so.