Austrian composer, born in Linz to parents both of whom were musicians. His father, Johann Weichlein, was organist in the monastery of Zwettl (Lower Austria), later moving to Linz, where he was employed from 1639 to 1677 as city organist, and where he owned a restaurant. Johann had nine children with his wife Sabina, of whom Romanus and his older brother Magnus became musicians. Probably both brothers attended the Humaniora in the Lambach monastery; both entered the Benedictine order as novices, Magnus in 1666 and romanus in 1671. Both studied and got their doctorates at the University of Salzburg, where Romanus reportedly met Biber, although it is difficult otherwise to trace their musical education. Undoubtedly one of their moist influential teachers was Beniamin Ludwig Ramhaufski (ca. 1631-1694), organist of the Lambach monastery, who may well have been thir initial connection with Lambach since his first wife Anna (née Siemer) was born in Linz. Ramhaufski himself was from Prague, also spending time in Passau, and had personal connection to Linz, the capital city of Upper Austria. The close relationship with the Weichlein family became even clearer after the death of Anna in 1678: documents from Lambach monastery record the marriage in May 1679 of "H. Beniamin Ludovicus Ramhaufski, organist" to Anna Barbara Weichlein of Linz, the marriage ceremony being performed by "Pater Romanus."
In fact, after his ordination, Romanus rarely went to Lambach. A letter from a fellow monk, Pater Georg Schönberger, reveals that in 1684 he was the spiritual father in the small parish of Oberkirchen in Lower Austria, when he was promoted to chaplain and musical prefect of the Benedictine convent of Nonnberg (the oldest continually existing nunnery in the world) in Salzburg. On September 22, 1691, the Nonnberg abbess wrote to the abbot of Lambach requesting the services of the venerable P. Roman Weichlein, for the newly founded Expositur in Säben in the Southern Tyrol as chaplain and musical instructor. The request was granted, and Weichlein took up his post on October 16, 1691, remaining in service until January 1705. After briefly returning to Lambach, he left again for Kleinfrauenhaid in present-day Burgenland, and incorporated parish of Lambach, where he died a year later in 1706 of the plague.
Reports are mixed of Weichlein as a personality. The Salzburg abbess praised him highly in seeking his services, and he left Säben with the warmest of references. However, the aforementioned letter from P. Georg Schönberger tells a different tale: he was sent to Säben as a monastic visitor to investigate the riots caused by Weichlein's violent outbursts. According to Schönberger, Weichlein told his cook "if you say only three words to me that I don't like, I will beat you so that you will remember it for the rest of your life." When the scolded cook attempted to defend herself verbally, Romanus chased her to her room and then reportedly broke down the door, whereupon they fought using objects to hand.
Weichlein published two collections during his lifetime: Parnassus Ecclesiastico-Musicus (Ulm 1702), a collection of works composed for the liturgy in Säben, and Encaenia Musices (Oeneponti 1695). Manuscripts survive in the Kremsmünster, Salzburg-Noonberg and Lambach abbey archives. Although Romanus Weichlein remains in the shadow of his great contemporaries Schmelzer, Biber and Muffat, he nevertheless developed, perhaps in part arising from his eccentric nature, a quite individual personal style, justly securing him a solid place in the history of music.