The departure from the breakfast slot of Adrian Goldberg from BBC WM contributed to a plunge in listener figures, the station has revealed.
Quarter-on-quarter, the station has taken a substantial knock with the number of people tuning in on an average week down from from 353,000 to 275,000.
Keith Beech, managing editor, said: "We knew the period following Adrian's departure the period might by difficult but our new presenter Phil Upton is in now in place and we're very confident for the future. Year-on-year the figures are roughly equivalent, but quarter-on-quarter they are disappointing."
The latest figures from industry number-cruncher RAJAR showed a broad trend for a dip in weekly reach – the number of listeners tuning in on an average week – in the quarter ending September 17, compared with the previous period.
One station bucking the trend was Kerrang! 105.2 which saw figures rising from 363,000 to 398,000.
Brand manager Andy Price said: "Overall, the best figures we've ever had. We're delighted. It's come on the back of a lot of hard work and lot of marketing work over the summer as well as a serious focus on live events. It's really worked for us."
Birmingham-based Saga 105.7fm saw a total 415,000 in the previous quarter drop in the latest round of figures to 382,000.
GCap's BRMB saw its reach figures drop to 483,000 from 519,000.
Chrysalis-owned 100.7 Heart fm based on Birmingham's Broad Street, also saw its figures drop - from 820,000 to 792,000. However the station said year on listening figures had increased "by a staggering 16 per cent" year-on-year.
Anita Wright, station director for Chrysalis Radio Midlands, said: "The fact that we’re up year-on-year is a great achievement and certainly news for our advertisers to feel good about.
"We’ve just had a record-breaking month for our revenue targets."
Sister Station Galaxy Birmingham dropped quarter-on-quarter from 348,000 to 332,000.