GIRM 104. It is fitting that there be a cantor or a choir director to direct and support the people’s singing. Indeed, when there is no choir, it is up to the cantor to direct the different chants, with the people taking the part proper to them.

Sing to the Lord
The Cantor
37. The cantor is both a singer and a leader of congregational song. Especially when no
choir is present, the cantor may sing in alternation or dialogue with the assembly. For example, the cantor may sing the invocations of the Kyrie, intone the Gloria, lead the short acclamations at the end of the Scripture readings, intone and sing the verse of the Gospel Acclamation, sing the invocations of the Prayer of the Faithful, and lead the singing of the Agnus Dei. The cantor may also sing the verses of the psalm or song that accompany the Entrance, Preparation of the Gifts, and Communion. Finally, the cantor may serve as psalmist, leading and proclaiming the verses of the Responsorial Psalm.

38. As a leader of congregational song, the cantor should take part in singing with the
entire gathered assembly. In order to promote the singing of the liturgical assembly, the cantor’s voice should not be heard above the congregation. As a transitional practice, the voice of the cantor might need to be amplified to stimulate and lead congregational singing when this is still weak. However, as the congregation finds its voice and sings with increasing confidence, the cantor’s voice should correspondingly recede. At times, it may be appropriate to use a modest gesture that invites participation and clearly indicates when the congregation is to begin, but gestures should be used sparingly and only when genuinely needed.

39. Cantors should lead the assembly from a place where they can be seen by all without
drawing attention from the liturgical action. When, however, a congregation is singing very familiar responses, acclamations, or songs that do not include verses for the cantor alone, the cantor need not be visible.

40. The cantor exercises his or her ministry from a conveniently located stand, but not
from the ambo. The cantor may dress in an alb or choir robe, but always in clean, presentable, and modest clothing. Cassock and surplice, being clerical attire, are not recommended as vesture for the cantor.

Some congregations sing robustly, when a sympathetic, confident solo voice sings with them.

They follow that voice in the way the documents imagine that they ought to follow the instruments alone.

Amplifying with intent to pull the plug seems like a bait-and-switch. They get confident following a thing, and then it changes.

If you want to do the thing unamplified ever, then amplify never. Plant strong voices in the pews who follow the organ, and exemplify that, in order to achieve your desired result.

Imho, however, voices most naturally are led by other voices. In the ideal situation, after all, a choir leads the singing.

People do not sing better when a so-called 'cantor' is singing into a microphone. The impression of greater singing is given because all one hears is the amplified voice of the so-called 'cantor'. Cantors (and those who think that they are cantors) should never sing into microphones - and anyone who needs one to be heard should not be standing in place of a real cantor. Further, it is the organ people should be following for hymns and such - not a song leader.

You have it right. If I were you I would stop cantoring if I were expected or required electronically to amplify my voice.

At the end of para 37 of Sing to the Lord there is an important but much misunderstood point.

Finally, the cantor may serve as psalmist, leading and proclaiming the verses of the Responsorial Psalm.

The roles of psalmist and cantor are different, the role of psalmist is the one you have accepted. Song leadership is best done by the organ*, but it is not a charism posessed by everyone who can play the organ well. There is helpful advice in this series Do it Rite by Fr Anthony Ruff OSB (they are listed here in reverse order).
Also these two https://www.praytellblog.com/index.php/2014/09/29/the-organ-is-too-loud-and-so-is-the-piano/ and https://www.praytellblog.com/index.php/2014/09/30/the-organ-is-too-loud-as-so-is-the-piano-part-ii/
* GIRM is written from the stance of the ideal music being unaccompanied chant for which clearly a cantor is needed.

My own experience is a cantor in front of a microphone inhibits congregational singing by overpowering them. My cantors do not have microphones, they are in the loft with me, and they start the first phrase or so of the hymns then back off and sing with the congregation. It seems to work fine for us. I should note we don't routinely throw new material at the congregation - oops, assembly or whatever. Bleah!

I have had Sundays when the cantor did not show up for legitimate reasons. The congregation sang the mass Ordinary by following the organ.

Another significant comment in "Sing to the Lord" is

When, however, a congregation is singing very familiar responses, acclamations, or songs that do not include verses for the cantor alone, the cantor need not be visible.

IMHO an important point of liturgy is that the congregational responses acclamations and songs should be familiar. In other words: the Ordinary is the people's part, and the Common responses. You can, and may need to, ask the congregation to take on the role of choir, in part or whole, but in so far as you do they need direction just as the choir would.

CGZ - I don't see that as "certain limited circumstances", I see those as the normal circumstances; except when the cantor is acting as psalmist. Only when the congregation has taken on the role of choir/schola should there be any need to see the cantor. In a small church of course they may need to act as schola routinely. Even then music can, and I believe should, only require visibilty of the cantor if it has verses for the cantor alone, as STTL says.
OTOH cantor is a visible role in much of the Church's traditional liturgy.

Why is an altar boy giving you directives?

I act as cantor (and psalmist) every week at an OF Mass with an organist and I sing in the choir loft. I do sing into a microphone, but I am very careful to remember my place is as song leader and our parishioners are accustomed to hearing a song leader. I never sing solos or take liberties with the hymns to make them seem like solos. Our congregation does sing the ICEL English ordinaries with accompaniment of the organ and chants the Our Father very well. During the Our Father, which is unaccompanied, the celebrant leads and the people join in. When it is time to sing "For the kingdom..." I do use the microphone to get people started up again and all in the same key. All these choices are those of the organist.

Why is an altar boy giving you directives?

Because Father instructed so?
Similar to how I sometimes send one of my kids to tell the other kids something.

---

Re: congregational singing at a Vigil Mass, with/without a mic:
It has been my experience that most who habitually attend the Saturday night Vigil Mass don't want to sing, and would be more than happy with absolutely no music at that Mass, at all.

Pretending that priests don't tend to assume mic'd cantors/choirs will encourage congregational singing isn't helpful. And they aren't completely wrong - many non-vocalists simply aren't confident in singing along to "background music."
For that matter, they might not even know that they are supposed to be singing along, if they can't hear someone else!

Stuffing the pews with choir members, not even necessarily to be heard, but to be seen as PIPs interested in singing hymns, I think would encourage more actual PIPs to sing.

However, many may just not want to... no matter how much they may grumble about a lack of things with which to "participate."

Our parish sings well when they know the hymns. We use OCP and they recommend and our organist chooses the recommended hymns, which are often unfamiliar to PIPs and so having a song leader, in my opinion, does assist the PIPs to join in. The style of organ introduction, where there is a pause of indeterminate length and then the singing starts, makes it challenging to know the timing to begin singing unless one has eye contact with the organist. Somebody has to get the ball rolling in this case.

I agree that only in emergencies should an altar server be delivering instructions to the cantor.

I despise singing into a microphone at church, and have mostly been permitted not to use it. I sing everything from the loft except the Psalm, and I'd be happy(er) to do that from the loft as well.

The microphone (in my very much non-universal experience) encourages people to think of me as a 'soloist', which, at least in the sense that they mean it, is certainly not supposed to be how we operate.

People actually sang more when they knew it was all up to them.

That has been my experience too.

Our music director confirmed that the role of cantor in our parish does include song leading. I sang last night and it was not a big deal leading the songs, and I do think it brought out the congregation a wee bit. But, as I told the DM, I've been content with just being the psalmist mostly because my voice is so often "iffy." Once the Alleluia is sung, I always breathe a little sigh of relief that I'm "done" for that Mass. Also, I am very uncomfortable being up front in that role. (The organ is to the side of the altar which is where all singers sit as well.) So I told her I will continue until the end of the year or until a replacement for my spot on the rotation can be found.

Thank you all for your helpful input!

That being said, there is one large, newer church in town so acoustically dead that microphones are required.

Is a renovation project in order in this building, such that this parish become acoustically live and thus microphone free?