He is best known for playing in CMX, a band he joined in 1990, replacing Kimmo Suomalainen.

He has also released two albums with Sapattivuosi, a Black Sabbath tribute band.

[2] His playing has been influenced by bands such as the Sex Pistols, Judas Priest, Yes and Genesis.

[3] In addition to his guitar playing, he has also done radio work for Radio Helsinki, hosting a weekly show "Sabotaasi" and "Heviurpot", where he and Lasse Kurki played 1980s hard rock classics.

[4] Halmkrona has co-produced two CMX albums, Veljeskunta (1991) and Aion (2003), as well as Sodankylä (2004) by Maj Karma.