The phrase "a marvelous effect" is correct and usable in written English.
You can use it to describe a positive and impressive outcome or result of an action, event, or object.
Example: "The lighting in the theater created a marvelous effect, enhancing the overall atmosphere of the performance."
Alternatives: "a stunning impact" or "an amazing result."
The performers sing parts of it — a marvelous effect.
At "La Bête" the night after the Adler benefit, Mr. Rylance said he felt that the improv had a "marvelous effect" on his stage work, which requires him, as Valere, to revel in his own perceived brilliance while chastising himself for going too far — all in rhyming couplets.
FFRF's attack on the housing allowance had a marvelous effect on the ecumenical movement.
That was followed by Ellis and her broad vocal range used to marvelous effect in "Feed The 'Burbs," a naughty spin on Mary Poppins and the tourist trade.
Its marvelous effect lay altogether in its artistic arrangement as a picture.
The boisterous and essentially harmless if overwhelming Mrs. Jennings is an ideal fit for Tucker, who here uses his imposing size to marvelous effect without ever stopping to caricature.
This competition can be used to marvelous effect.
Bit by bit, to marvelous effect, the choreography of the Broadway musical "Matilda" becomes central to the whole production.
"Many of us [can] never forget the marvelous effect produced upon all minds" by Garibaldi, William Gladstone, then Chancellor of the Exchequer, declared.
In the long dance sequences at the end of "Center Stage," Mr. Hytner's camera follows the performers without stepping on their toes, to marvelous effect.
A harlequin print of romantic triangles involving dancers, choreographers and the academy's fearsome artistic director (Peter Gallagher, Nicholas Hytnerr's film is best in dance scenes when it "follows the performers without stepping on their toes, to marvelous effect" (Scott).
