Motional Feedback (MFB) block diagram

the MFB speaker.

MFB signal

Frequency sweep without (B) and with MFB (A).

Original sinewave.

Sinewave MFB switched off.

Sinewave MFB switched on.

MFB overview

RH 532

Type: 22 RH 532 /00/15/44/50/65/66

Number of speakers: 3
Low unit: AD 8065/MF4
Mid unit: AD 5060/Sq8
High unit: AD 0160/T8

Number of amplifiers: 2
Output low: 40 W
Output mid/high: 20 W
Outputcapacitor amplifiers: yes
Cross-over frequency: 500 Hz (active) + 3500 Hz (passive)
Year :
Notes: first Philips MFB loudspeaker.

a MFB family

RH 541

Type: 22 RH 541 /00/15

Number of speakers: 2
Low/mid unit: AD 7066/W4
High unit: AD 0161/T8

Number of amplifiers: 1
Output: 30 W
Outputcapacitor amplifier: yes
Cross-over frequency: 1400 Hz (passive)
Dimensions (h x w x d): 295 x 230 x 175 mm.
Year : 1975
Notes: My favorit MFB speaker.

Type: 22 RH 541 /50/65

Number of speakers: 2
Low/mid unit: AD 7066/W4
High unit: AD 0140/T8

Number of amplifiers: 1
Output: 30 W
Outputcapacitor amplifier: yes
Cross-over frequency: 1400 Hz (passive)
Year : 1978
Notes:

Type: 22 RH 541 /80/85/89

As 22 RH 541 /50/65/79
However, the difference is the main-switch which has been added for the versions /80/85/89.

the RH 544 MFB loudspeaker

RH 544

Type: 22 RH 544 /00R/15R

Number of speakers: 3
Low unit: AD 8067/MF4
Mid unit: AD 0210/Sq8
High unit: AD 0160/T8

Number of amplifiers: 2
Output low: 40 W
Output mid/high: 20 W
Outputcapacitor amplifiers: yes
Cross-over frequency: 500 Hz (active) + 4 kHz (passive)
Dimensions (h x w x d): 387 x 287 x 216 mm.
Year :
Notes: includes 7 kHz adjustable roll-off filter (active).

Type: 22 RH 544 /65R/79R

As 22 RH 544 /00R/15R. However no adjustable 7 kHz roll-off filter, no switch automatic switch-on/off, no additional main outlet.

RH 567

Type: 22 RH 567 /00R

Number of speakers: 3
Low unit: AD 10100/MFB4
Mid unit: AD 0210/Sq8
High unit: AD 0160/T8

Number of amplifiers: 2
Output low: 40 W
Output mid/high: 20 W
Outputcapacitor amplifiers: yes
Cross-over frequency: 500 Hz (active) + 3500 Hz (passive)
Dimensions (h x w x d): 540 x 320 x 273 mm.
Year :
Notes:

Type: 22 RH 567 /80R/89R

Number of speakers: 3
Low unit: AD 10100/MFB4
Mid unit: AD 0211/Sq8
High unit: AD 0163/TE8
Year: 1978

RH 545

Type: 22 RH 545 /00R/16R

Number of speakers: 3
Low unit: AD 12100/MFB4
Mid unit: AD 0210/Sq8
High unit: AD 0162/T8

Number of amplifiers: 3
Output low: 50 W
Output mid: 35 W
Output high: 15 W
Outputcapacitor amplifiers: low: no ; mid/high: yes
Cross-over frequency: 500 Hz (active) + 3 kHz (active)
Dimensions (h x w x d): 650 x 436 x 320 mm.
Year :
Notes: Number of correction filters and roll-off filters.

the AH 586 and the AH 585 MFB , not shown the AH 587 and RH 545

RH 585

Type: 22 RH 585 /00/15/29

Number of speakers: 2
Low/mid unit: AD 07066/MFB4
High unit: AD 01635/T15

Number of amplifiers: 2
Output low: 30 W
Output mid/high: 5 W
Outputcapacitor amplifiers: no
Cross-over frequency: 1500 Hz (12dB active)
Dimensions (h x w x d): 350 x 230 x 200 mm.
Year : 1979
Notes:

RH 586

Type: 22 RH 586 /00/15/29

Number of speakers: 2
Low/mid unit: AD 8167/MFB4
High unit: AD 01635/T8

Number of amplifiers: 2
Output low: 40 W
Output mid/high: 5 W
Outputcapacitor amplifiers: no
Cross-over frequency: 1500 Hz (active)
Dimensions (h x w x d): 375 x 260 x 210 mm.
Year : 1979
Notes: additional corrections Rear to wall; Floor; Side to wall.

RH 587

Type: 22 RH 587 /00R/15/29

Number of speakers: 3
Low unit: AD 8167/MFB4
Mid unit: AD 0211/Sq8
High unit: AD 0163/T15

Number of amplifiers: 3
Output low: 50 W
Output mid: 20 W
Output high: 5 W
Outputcapacitor amplifiers: no
Cross-over frequency: 650 Hz + 3500 Hz (active)
Dimensions (h x w x d): 650 x 436 x 320 mm
Year : 1979
Note: additional corrections Rear to wall; Floor; Side to wall.

Type: 22 RH 587 /50/66

As 22 RH 587 /00R/15/29. However fronts are black anodised.
Year: 1983

A dedicated MFB Pre-Amplifier, the RH551 (1975).

High End MFB Pre-Amplifier, the AH280 (1980).