Microphonics: Difference between revisions
Add reference for piezo effect of High K caps |
m simplify link |
||
| (61 intermediate revisions by 41 users not shown) | |||
| Line 1: | Line 1: | ||
{{Redirect|Microphony|the similarly titled compositions by Karlheinz Stockhausen|Mikrophonie}} |
|||
{{Unreferenced|date=January 2008}} |
|||
{{Redirect|Valve hammer|the level editor|Valve Hammer}} |
|||
{{Use dmy dates|date=January 2020|cs1-dates=y}} |
|||
| ⚫ | |||
| ⚫ | '''Microphonics''' describes the phenomenon |
||
| ⚫ | '''Microphonics''', '''microphony''', or '''microphonism'''<ref name="ActaTechnica_1956"/><ref name="Korn_1956"/><ref name="Electronics_1956"/> describes the phenomenon wherein certain components in [[Electronics|electronic]] devices transform mechanical [[vibration]]s into an undesired electrical signal ([[noise (electronics)|noise]]). The term comes from analogy with a [[microphone]], which is intentionally designed to convert vibrations to electrical signals. |
||
| ⚫ | When electronic equipment was built using [[vacuum tube]]s, microphonics |
||
==Description== |
|||
With the advent of [[solid state electronics]] ([[transistor]]s), this major source of microphonics was eliminated but smaller sources still remain. The [[ceramic]] [[dielectric]]s used in [[high-K]] [[capacitor]]s ("[[Z5U]]" and "[[X7R]]") are [[piezoelectricity|piezoelectric]] and will directly transform mechanical vibration into a voltage in exactly the same fashion as a ceramic microphone <ref name="Kemet">[http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/vaFeedbackFAQ/118EBDDDFA5D532C852572BF0046B776/$file/2007%20CARTS%20-%20Reduced%20Microphonics%20and%20Sound%20Emissions.pdf], Capacitors for reduced sound emissions.</ref>. Wiring and cables can also exhibit microphonics as charged conductors move around and various materials can develop [[triboelectricity|triboelectric]] ("static") charges that couple to the electronic circuits. |
|||
| ⚫ | When electronic equipment was built using [[vacuum tube]]s, microphonics were often a serious design problem. The charged elements in the vacuum tubes can mechanically vibrate, changing the distance between the elements, producing charge flows in and out of the tube in a manner identical to a capacitor microphone. A system sufficiently susceptible to microphonics could experience [[audio feedback]], and make noises if jarred or bumped. To minimize these effects, some vacuum tubes were made with thicker internal insulating plates and more supports,<ref name="Tomer_1960"/> and tube-socket assemblies were sometimes [[shock-mount]]ed by means of small [[rubber grommet]]s placed in the screw holes to isolate them from vibration.<ref name="Korn_1956"/> |
||
[[File:Valve hammer.jpg|thumb|Radio and TV repairman's tool for testing microphony in vacuum tubes. The black rubber grommet gives the tube a firm but safe impact. Pen for scale.]] |
|||
| ⚫ | |||
A special tool, called a valve hammer, or tube hammer was sometimes used to safely tap the device suspected of being microphonic, while it was operating, so checking if such a tap would produce objectional audio effects.<ref name="ActaTechnica_1956"/> |
|||
Microwave tube designers took numerous steps to reduce microphonics in [[klystron]]s. Where tuning was essential, a compromise usually was made between the resistance of the klystron to microphonism and the obtainable performance.<ref name="Electronics_1956"/> |
|||
==Other uses== |
|||
* The term is sometimes used to describe the sounds physically produced by mechanical [[vibrations]] or knocks on the wires of a [[headphone]] or [[in-ear monitor]], where no current induction occurs. [http://www.macworld.com/article/55152/2007/01/canalphones.html] |
|||
With the advent of [[solid-state electronics]] ([[transistor]]s), this major source of microphonics was eliminated but smaller sources still remain. |
|||
| ⚫ | |||
The [[ceramic]] [[EIA Class 2 dielectric]]s used in [[high-κ]] [[capacitor]]s ("[[Z5U]]" and "[[X7R]]") are [[piezoelectric]] and directly transform mechanical vibration into a voltage in exactly the same way as a ceramic or piezoelectric microphone.<ref name="Kemet_2007"/> [[Film capacitor]]s using soft (mechanically compliant) [[dielectric]] materials can also be microphonic due to vibrational energy physically moving the plates of the capacitor{{Citation needed|reason=unable to find source. might be original research.|date=August 2018}}. Likewise, variable capacitors using air as a dielectric are vulnerable to vibrations moving the plates. Capacitors using [[glass]] as the dielectric, while quite expensive, can be made to be essentially non microphonic. |
|||
| ⚫ | |||
Wiring, cables and even [[printed circuit board]]s (PCB) can also exhibit microphonics as charged conductors move around, and various materials can develop [[triboelectric]] charges (a type of [[static electricity]]) that couple to the electronic circuits. |
|||
| ⚫ | |||
| ⚫ | |||
| ⚫ | [[Guitar amplifier]]s that incorporate the electronic [[chassis]] into the same cabinet as the speaker are susceptible to microphonics. Though a guitar amplifier's microphonics distortion is sometimes appreciated as part of the "special sound" of a guitar amplifier, a faulty vacuum tube or other component can cause out-of-control [[positive feedback]]. Unwanted microphonics-related audible distortions can often be alleviated by using commercially available vacuum tube mechanical dampers. |
||
{{tech-stub}} |
|||
The term may also be used to describe a video artifact common in older video cameras. Before the introduction of solid-state [[charge-coupled device]] (CCD) sensors to produce the image, [[Video camera tube|vacuum tubes]] performed this task. Loud noises in the studio, such as rock bands or gunshot effects would cause the tubes to vibrate, producing a characteristic undesirable horizontal banding in the image.<ref name="Demtschyna_2002"/> |
|||
[[de:Mikrofonie]] |
|||
The effect can also be observed when operating a [[record player]] in the same room as the loudspeakers. Depending on the construction of the player the sound may acoustically couple into the record player's dust cover or other mechanical parts and cause a feedback loop into the pickup cartridge. |
|||
Many [[In-ear monitor]]s exhibit microphonics when headphone cables transfer vibrations due to cable movement directly to the wearers ears.<ref name="Frakes_2007"/> |
|||
== See also == |
|||
* [[Audio spill]] |
|||
* [[Cable grommet]] |
|||
* [[Crosstalk]] |
|||
* [[Ringing (signal)]] |
|||
== References == |
|||
| ⚫ | |||
<ref name="ActaTechnica_1956">{{cite book |title=Acta Technica - Academiae Scientiarum Hungaricae |author-first=Iván Péter |author-last=Valkó |author-link=:hu:Valkó Iván Péter |volume=15 |date=1956 |publisher=[[Magyar Tudományos Akadémia]] |location=Budapest, Hungaria |pages=229–231 |url=https://books.google.com/books?id=dKAIAQAAIAAJ |access-date=2013-04-17}}</ref> |
|||
<ref name="Korn_1956">{{cite book |author-first1=Granino Arthur |author-last1=Korn |author-first2=Theresa M. |author-last2=Korn |title=Electronic analog computers (d-c analog computers) |date=1956 |edition=2 |publisher=[[McGraw-Hill]] |pages=157, 248–249 |url=https://books.google.com/books?id=l4BQAAAAMAAJ |access-date=2013-04-17}}</ref> |
|||
<ref name="Electronics_1956">{{cite book |title=Electronics |chapter=Nonmicrophonic Klystron |author-first=Roger A. |author-last=La Plante |location=Philips Laboratories, Irvington-on-Hudson, NY, USA |volume=29 |date=July 1956 |publisher=[[McGraw-Hill Publishing Company]] |pages=238, 241 |url=https://books.google.com/books?id=_DkjAQAAMAAJ |access-date=2013-04-17}}</ref> |
|||
<ref name="Tomer_1960">{{cite book |author-first=Robert B. |author-last=Tomer |title=Getting the most out of Vacuum Tubes |chapter=Chapter 3: Subjective Failures: Microphonics |pages=48–50 |publisher=[[Howard W. Sams & Co., Inc.]] |series=Photofact Publication |location=Indianapolis, USA |date=July 1960 |edition=first printing, first |id=VTT-1 |lccn=60-13843 |url=http://www.tubebooks.org/Books/Atwood/Tomer%201960%20Getting%20the%20Most%20Out%20of%20Vacuum%20Tubes.pdf |access-date=2020-01-31 |url-status=live |archive-url=https://web.archive.org/web/20190715223356/http://tubebooks.org/Books/Atwood/Tomer%201960%20Getting%20the%20Most%20Out%20of%20Vacuum%20Tubes.pdf |archive-date=2019-07-15}} [https://archive.org/details/Tomer_1960_Getting_the_Most_Out_of_Vacuum_Tubes/mode/2up]</ref> |
|||
<ref name="Demtschyna_2002">{{cite web |title=Video Artefacts - Microphony |author-first=Michael |author-last=Demtschyna |work=Michael D's DVD |date=2002 |url=http://www.michaeldvd.com.au/Articles/VideoArtefacts/VideoArtefactsMicrophony.html |access-date=2020-01-31 |url-status=live |archive-url=https://web.archive.org/web/20190611185854/http://www.michaeldvd.com.au/Articles/VideoArtefacts/VideoArtefactsMicrophony.html |archive-date=2019-06-11}}</ref> |
|||
<ref name="Kemet_2007">{{cite web |title=Capacitors for Reduced Microphonics and Sound Emission |author-first1=Mark |author-last1=Laps |author-first2=Roy |author-last2=Grace |author-first3=Bill |author-last3=Sloka |author-first4=John |author-last4=Prymak |author-first5=Xilin |author-last5=Xu |author-first6=Pascal |author-last6=Pinceloup |author-first7=Abhijit |author-last7=Gurav |author-first8=Michael |author-last8=Randall |author-first9=Philip |author-last9=Lessner |author-first10=Aziz |author-last10=Tajuddin |publisher=[[KEMET Electronics Corporation]], Electronic Components, Assemblies & Materials Association (ECA), Arlington, VA. |date=March 2007 |series=CARTS 2007 Symposium Proceedings |location=Albuquerque, NM, USA |url=http://www.kemet.com/kemet/web/homepage/kfbk3.nsf/vaFeedbackFAQ/118EBDDDFA5D532C852572BF0046B776/$file/2007%20CARTS%20-%20Reduced%20Microphonics%20and%20Sound%20Emissions.pdf |access-date=2020-01-31 |url-status=live |archive-url=https://web.archive.org/web/20191116171801/http://www.kemet.com/Lists/TechnicalArticles/Attachments/62/2007%20CARTS%20-%20Reduced%20Microphonics%20and%20Sound%20Emissions.pdf |archive-date=2019-11-16}} (8 pages)</ref> |
|||
<ref name="Frakes_2007">{{cite web |title=In-ear-canal headphone primer |author-first=Dan |author-last=Frakes |series=Headsets |journal=[[Macworld]] |publisher=[[IDG]] |date=2007-01-31 |url=http://www.macworld.com/article/55152/2007/01/canalphones.html |access-date=2020-01-31 |url-status=live |archive-url=https://web.archive.org/web/20190328053228/https://www.macworld.com/article/1055152/canalphones.html |archive-date=2019-03-28}}</ref> |
|||
}} |
|||
== External links == |
|||
* [http://www.thevalvepage.com/valvetek/microph/microph.htm Valve microphonics] at The Valve Page |
|||
| ⚫ | |||
[[Category:Radio technology]] |
|||
| ⚫ | |||
Latest revision as of 18:28, 28 November 2024
Microphonics, microphony, or microphonism[1][2][3] describes the phenomenon wherein certain components in electronic devices transform mechanical vibrations into an undesired electrical signal (noise). The term comes from analogy with a microphone, which is intentionally designed to convert vibrations to electrical signals.
Description
[edit]When electronic equipment was built using vacuum tubes, microphonics were often a serious design problem. The charged elements in the vacuum tubes can mechanically vibrate, changing the distance between the elements, producing charge flows in and out of the tube in a manner identical to a capacitor microphone. A system sufficiently susceptible to microphonics could experience audio feedback, and make noises if jarred or bumped. To minimize these effects, some vacuum tubes were made with thicker internal insulating plates and more supports,[4] and tube-socket assemblies were sometimes shock-mounted by means of small rubber grommets placed in the screw holes to isolate them from vibration.[2]
A special tool, called a valve hammer, or tube hammer was sometimes used to safely tap the device suspected of being microphonic, while it was operating, so checking if such a tap would produce objectional audio effects.[1]
Microwave tube designers took numerous steps to reduce microphonics in klystrons. Where tuning was essential, a compromise usually was made between the resistance of the klystron to microphonism and the obtainable performance.[3]
With the advent of solid-state electronics (transistors), this major source of microphonics was eliminated but smaller sources still remain.
The ceramic EIA Class 2 dielectrics used in high-κ capacitors ("Z5U" and "X7R") are piezoelectric and directly transform mechanical vibration into a voltage in exactly the same way as a ceramic or piezoelectric microphone.[5] Film capacitors using soft (mechanically compliant) dielectric materials can also be microphonic due to vibrational energy physically moving the plates of the capacitor[citation needed]. Likewise, variable capacitors using air as a dielectric are vulnerable to vibrations moving the plates. Capacitors using glass as the dielectric, while quite expensive, can be made to be essentially non microphonic.
Wiring, cables and even printed circuit boards (PCB) can also exhibit microphonics as charged conductors move around, and various materials can develop triboelectric charges (a type of static electricity) that couple to the electronic circuits.
Guitar amplifiers that incorporate the electronic chassis into the same cabinet as the speaker are susceptible to microphonics. Though a guitar amplifier's microphonics distortion is sometimes appreciated as part of the "special sound" of a guitar amplifier, a faulty vacuum tube or other component can cause out-of-control positive feedback. Unwanted microphonics-related audible distortions can often be alleviated by using commercially available vacuum tube mechanical dampers.
The term may also be used to describe a video artifact common in older video cameras. Before the introduction of solid-state charge-coupled device (CCD) sensors to produce the image, vacuum tubes performed this task. Loud noises in the studio, such as rock bands or gunshot effects would cause the tubes to vibrate, producing a characteristic undesirable horizontal banding in the image.[6]
The effect can also be observed when operating a record player in the same room as the loudspeakers. Depending on the construction of the player the sound may acoustically couple into the record player's dust cover or other mechanical parts and cause a feedback loop into the pickup cartridge.
Many In-ear monitors exhibit microphonics when headphone cables transfer vibrations due to cable movement directly to the wearers ears.[7]
See also
[edit]References
[edit]- ^ a b Valkó, Iván Péter [in Hungarian] (1956). Acta Technica - Academiae Scientiarum Hungaricae. Vol. 15. Budapest, Hungaria: Magyar Tudományos Akadémia. pp. 229–231. Retrieved 2013-04-17.
- ^ a b Korn, Granino Arthur; Korn, Theresa M. (1956). Electronic analog computers (d-c analog computers) (2 ed.). McGraw-Hill. pp. 157, 248–249. Retrieved 2013-04-17.
- ^ a b La Plante, Roger A. (July 1956). "Nonmicrophonic Klystron". Electronics. Vol. 29. Philips Laboratories, Irvington-on-Hudson, NY, USA: McGraw-Hill Publishing Company. pp. 238, 241. Retrieved 2013-04-17.
- ^ Tomer, Robert B. (July 1960). "Chapter 3: Subjective Failures: Microphonics". Getting the most out of Vacuum Tubes (PDF). Photofact Publication (first printing, first ed.). Indianapolis, USA: Howard W. Sams & Co., Inc. pp. 48–50. LCCN 60-13843. VTT-1. Archived (PDF) from the original on 2019-07-15. Retrieved 2020-01-31. [1]
- ^ Laps, Mark; Grace, Roy; Sloka, Bill; Prymak, John; Xu, Xilin; Pinceloup, Pascal; Gurav, Abhijit; Randall, Michael; Lessner, Philip; Tajuddin, Aziz (March 2007). "Capacitors for Reduced Microphonics and Sound Emission" (PDF). CARTS 2007 Symposium Proceedings. Albuquerque, NM, USA: KEMET Electronics Corporation, Electronic Components, Assemblies & Materials Association (ECA), Arlington, VA. Archived (PDF) from the original on 2019-11-16. Retrieved 2020-01-31. (8 pages)
- ^ Demtschyna, Michael (2002). "Video Artefacts - Microphony". Michael D's DVD. Archived from the original on 2019-06-11. Retrieved 2020-01-31.
- ^ Frakes, Dan (2007-01-31). "In-ear-canal headphone primer". Macworld. Headsets. IDG. Archived from the original on 2019-03-28. Retrieved 2020-01-31.
External links
[edit]- Valve microphonics at The Valve Page