DVC Speed Feedback

steph_tsf

Member
2008-03-27 12:21 pm
hello, attached you will find a few speed feedback loudspeaker arrangements using a Dual Voice Coil (DVC) speaker driver, with one of the two coils being used as speed sensor. For maximizing the speed feedback, the loudspeaker needs to be current driven. The simulation results look interesting. See attached pictures. Can somebody help me refining the simulations, taking into account the electromagnetic cross-coupling effect of the two coils ? Thanks. Steph. Use the .zip at your will.
 

Attachments

  • Speed Feedback Type 8b (f2 equalized f1f2 current drive).jpg
    Speed Feedback Type 8b (f2 equalized f1f2 current drive).jpg
    121.8 KB · Views: 106
  • Speed Feedback Type 8b (f2 equalized f1f2 current drive) curves.jpg
    Speed Feedback Type 8b (f2 equalized f1f2 current drive) curves.jpg
    169 KB · Views: 104
  • Speed Feedback.zip
    39.5 KB · Views: 8

steph_tsf

Member
2008-03-27 12:21 pm
Adding a passive driver may be interesting. The driver excursion becomes lower around the natural resonance frequency.
 

Attachments

  • Speed Feedback Type 09 (f2 equalized f1f2 current drive and passive driver).jpg
    Speed Feedback Type 09 (f2 equalized f1f2 current drive and passive driver).jpg
    103.5 KB · Views: 92
  • Speed Feedback Type 09 (f2 equalized f1f2 current drive and passive driver) curves.jpg
    Speed Feedback Type 09 (f2 equalized f1f2 current drive and passive driver) curves.jpg
    161.2 KB · Views: 89
  • Speed Feedback.zip
    46.5 KB · Views: 6

steph_tsf

Member
2008-03-27 12:21 pm
Actually, the results are nice using a damped vented box (bass-reflex). Adding a hole is less costly than adding a passive driver.
 

Attachments

  • Speed Feedback Type 10 (f2 equalized f1f2 current drive in damped bass-reflex).jpg
    Speed Feedback Type 10 (f2 equalized f1f2 current drive in damped bass-reflex).jpg
    105 KB · Views: 87
  • Speed Feedback Type 10 (f2 equalized f1f2 current drive in damped bass-reflex) curves.jpg
    Speed Feedback Type 10 (f2 equalized f1f2 current drive in damped bass-reflex) curves.jpg
    160.1 KB · Views: 21
  • Speed Feedback.zip
    49 KB · Views: 4

steph_tsf

Member
2008-03-27 12:21 pm
The dual chamber bandpass is also a possibility, making a subwoofer.
 

Attachments

  • Speed Feedback Type 11 (current drive in dual chamber bandpass).jpg
    Speed Feedback Type 11 (current drive in dual chamber bandpass).jpg
    107.8 KB · Views: 24
  • Speed Feedback Type 11 (current drive in dual chamber bandpass) curves.jpg
    Speed Feedback Type 11 (current drive in dual chamber bandpass) curves.jpg
    156.7 KB · Views: 23
  • Speed Feedback.zip
    51.1 KB · Views: 6
Last edited:

steph_tsf

Member
2008-03-27 12:21 pm
Adding a few circuits using an incremental approach. Taking into account the coils cross-coupling. The cross-coupling has two effects :

- At a critical frequency equal to roughly 300 Hz, the speed feedback gets counteracted in phase and in amplitude by the coil cross-coupling effect making the system operating in open-loop.
- Above the 300 Hz critical frequency, the coil-cross coupling is dominant in the feedback loop. This induces a closed-loop 1st-order lowpass behaviour above 300 Hz.

Any inductance non-linearity will cause distorsion in the frequency band where the coil-cross coupling dominates the feedback loop. THD could thus increase above 200 Hz or so, when applying coil feedback.
 

Attachments

  • Speed Feedback (DVC woofer).zip
    107.4 KB · Views: 3
  • Schema.jpg
    Schema.jpg
    131.8 KB · Views: 15
  • Bode plot.jpg
    Bode plot.jpg
    123.4 KB · Views: 19
Last edited: