I am a senior and a cradle Catholic. During all my years I was taught that during the Gloria of the Holy Thursday Mass bells were rung and the organ & choir sang. And then after that there was to be no musical accompanament until the Gloria of the Easter Vigil. But, in many recent years our choir has the organ play...even with the singing during Good Friday's Seven Last Words Service. When did this change occur??? I could not find the answer in a 2 hour search on line/ Thanks, Eileen
I don't know, Eileen: I've been at Good Friday services, and have heard the Reproaches sung, but without instrumental accompaniment.
I hadn't noticed!
I DID NOTICE they played the Celtic Alleluia!!!!!!!!!
That is MY favorite! I have been humming and singing it since I got home from Easter Vigil. I just really like that song a LOT!:D
I don't know when they changed that custom, but I do know that musical accompaniment is to be minimized, only to be used in aiding the congregation in song. That is, no "fill-in" music.
Paschales Solemnitatis, the Vatican document regarding the Holy Week liturgies and their rites, written in 1988, says the following about musical accompaniment between the two Glorias:
- During the singing of the hymn "Gloria in excelsis," in accordance with local custom, the bells may be rung but should thereafter remain silent until the "Gloria in excelsis" of the Easter Vigil, unless the conference of bishops or the local ordinary, for a suitable reason, has decided otherwise.  During the same period, the organ and other musical instruments may be used only for the purpose of supporting the singing. 
I'm only a young Catholic (in my 20s), but I remember our priest sending me up to the organ loft as a young server to tell the organist to stop the organ voluntary before the Good Friday service. The organ was then used during the service itself. Which would be in line with the note from Paschales Solemnitatis given above.