Rumble is a low frequency noise between 25 and 200 Hz that appears in old turntables, affecting the quality of reproduction. This noise is due to low frequency variations of engine rpm. The filter below cuts these noise, thereby facilitating the recovery of old recordings on turntables when passed on to other media. The component values depend on the cut-off frequency and the operational amplifiers 741 are of the type with symmetrical supply. We found the basic circuit in anold publication, making the necessary changes so that it becomes feasible in our times. The power supply must be symmetrical 9-15 V, with excellent filtration. Equivalent operational amplifiers can be used. Input is medium impedance and the output has sufficient signal level to excite most amplifiers.
| Cut Frequency | C | R |
| 25Hz | 100 nF | 62k |
| 50 Hz | 100 nF | 33k |
| 100 Hz | 100 nF | 15 k |
| 200 Hz | 100 nF | 7k5 |
