- Knowles

APPLICATION
NOTE AN-7
ELECTRONICS
FerrofluidTM Damped Receiver
Part Numbering System
To further assist designers in specifying the desired ferrofluid damped receiver, Knowles
Electronics has adopted the following part numbering system for ferrofluid receivers:
Series Designation - “F??”
The series name will be three (3) characters, starting with “F” to indicate ferrofluid damping,
followed by the existing two (2) characters of the base receiver series:
EF series
EC series
ED series
EP series
EH series
→
→
→
→
→
FEF series
FEC series
FED series
FEP series
FEH series
ES series
FC series
FD series
FH series
HC series
→
→
→
→
→
FES series
FFC series
FFD series
FFH series
FHC series
Base Model Number - “####”
The four (4) digit base model number will remain unchanged from the current non-ferrofluid
damped receiver.
Suffix - “-i##” or “-k##”
Suffices detail the amount of delta peak (∆peak) response that a particular ferrofluid damped
receiver has relative to it’s 1kHz sensitivity. The amount of damping / ∆peak response can be
selected for the first resonance peak (second resonance peak in units used with BTE tubing) and
will have an associated impact upon the other resonance peaks. The amount of ∆peak response
is selectable in 2dB increments from 2dB to the maximum undamped peak response of the
receiver series in question. All damping / ∆peak responses are for voltage drive conditions with
ITE tubing (10mm x 1mm) into a 2cc cavity (NOTE: For FEF receivers using BTE tubing, the -i##
delta peak values apply to the second resonance peak as the first resonance peak is due to the
BTE tubing arrangement).
The “-i##” suffices detail the first resonance ∆peak relative to 1kHz sensitivity:
FED-1739-i02 → First resonance ∆peak of 2dB relative to 1kHz sensitivity, ITE tubing
FES-7108-i06 → First resonance ∆peak of 6dB relative to 1kHz sensitivity, ITE tubing
FFH-3375-i04 → First resonance ∆peak of 4dB relative to 1kHz sensitivity, ITE tubing
application note
The maximum possible first peak ∆peak values are listed below:
FEF series:
FEC series:
FED series:
FEP series:
FEH series:
FES series:
FFC series:
FFD series:
FFH series:
FHC series:
8.0dB
8.0dB
8.0dB
8.0dB
9.0dB
7.0dB
6.5dB
6.5dB
6.5dB
6.0dB
max.
max.
max.
max.
max.
max.
max.
max.
max.
max.
∆peak; ∆peak values of 2dB, 4dB, and 6dB supported*
∆peak; ∆peak values of 2dB, 4dB, and 6dB supported
∆peak; ∆peak values of 2dB, 4dB, and 6dB supported
∆peak; ∆peak values of 2dB, 4dB, and 6dB supported
∆peak; ∆peak values of 2dB, 4dB, and 6dB supported
∆peak; ∆peak values of 2dB, and 4dB supported
∆peak; ∆peak values of 2dB, and 4dB supported
∆peak; ∆peak values of 2dB, and 4dB supported
∆peak; ∆peak values of 2dB, and 4dB supported
∆peak; ∆peak values of 2dB, and 4dB supported
* NOTE: For FEF receivers used with BTE tubing, these values apply to the second
resonance peak.
The “-k##” suffices detail any special damping requirements or other special features needed in
the ferrofluid damped reciever. Please note that “-k##” suffices will be selected on an individual
model and case-by-case basis and may not correspond to the above ∆peak numbering convention
(-i02 for 2dB ∆peak, -i04 for 4dB ∆peak, etc.).
Laser Marking
Ferrofluid damped receiver units are laser marked with the four (4) digit base model number plus
the appropriate suffix; examples are:
FEP-4108-i02
FFC-6171-i04
FEF-6348-i02
FED-7288-i04
→
→
→
→
Laser marked as “4108i02”
Laser marked as “6171i04”
Laser marked as “6348i06”
Laser marked as “7288i04”
The above part numbering system provides a framework for specifying ferrofluid damped
receivers; however, it cannot cover all aspects of custom receiver design. As always, please
contact your Knowles Electronics Account Representative for more detailed assistance relating to
your individual design(s).
Knowles Electronics LLC
1151 Maplewood Drive
Itasca, Illinois 60143
Phone: (630) 250-5100
Fax:
(630) 250-0575
www.knowles.com
Knowles Europe
York Road, Burgess Hill
West Sussex, RH15 9TT, England
Phone: (44) 1444 235432
Fax:
(44) 1444 248724
Knowles Electronics Japan KK
Kyodo Bloom Building
19-1 Miyasaka 2-Chome
Setagaya-Ku, Tokyo 156-0051, Japan
Phone: (81) 3 3439 1151
Fax:
(81) 3 3439 8822
Micromax Pty. Ltd.
P.O. Box 1238
Wollongong N.S.W.
2500, Australia
Phone: (61) 2 4226 6777
Fax:
(61) 2 4226 6602
Knowles Electronics Taiwan, Ltd.
53 Pao Hsing Road
Hsin Tien City, Taipei, Taiwan
Republic of China
Phone: (886) 2 2911 4931
Fax:
(886) 2 2918 6868
NOTE: Specifications are subject to change without notice. The information on this Application Note reflects typical applications. Specific test specifications
defining each model are available by requesting Outline Drawing Sheets 1.1 and Performance Specifications Sheets 2.1 of that model number. Knowles’
responsibility is limited to compliance with the Outline Drawing and the Performance Specification application to the subject model at time of manufacture.
Knowles Electronics LLC
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Issue 02 - 1003