Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Multi-Way Conventional loudspeakers with crossovers

Piezo compression
Piezo compression
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Thread Tools Search this Thread
Old 18th November 2004, 12:00 AM   #1
Pbassred is offline Pbassred  United Kingdom
diyAudio Member
Pbassred's Avatar
Join Date: Nov 2003
Location: N London
Send a message via MSN to Pbassred
Default Piezo compression

Are the terms: "piezo" and "compression" mutually exclusive when reffering to HF drivers?
Jeeees! I only asked
  Reply With Quote
Old 18th November 2004, 01:05 PM   #2
BillFitzmaurice is offline BillFitzmaurice  United States
Join Date: May 2004
Location: New Hampshire
No. Compression refers to when the diaphraghm rear is contained within a small sealed chamber, the intention being to raise the resonance of the system close to fc for maximum efficiency and to limit displacement. Piezoelectric is an alternative way of exciting a diaphraghm versus a voice coil. A driver therefore may be both piezo and compression. Or not.
  Reply With Quote
Old 18th November 2004, 02:53 PM   #3
Nappylady is offline Nappylady  United States
diyAudio Member
Nappylady's Avatar
Join Date: Feb 2003
Location: Salt Lake City
Send a message via ICQ to Nappylady Send a message via AIM to Nappylady Send a message via MSN to Nappylady Send a message via Yahoo to Nappylady
Which frequency is fc?
  Reply With Quote
Old 18th November 2004, 03:34 PM   #4
Puggie is offline Puggie  United Kingdom
diyAudio Member
Join Date: Oct 2004
Image Dynamics make a Piezo compression driver for use in the car, it doesn't like being drivern too hard but doesn't sound too bad.
  Reply With Quote
Old 18th November 2004, 06:01 PM   #5
bear is offline bear
expert in tautology
diyAudio Member
bear's Avatar
Join Date: Apr 2002
Location: New York State USA
Piezo compression
The term compression in speakers is actually used two ways, iirc.

One refers to the compression driver, the other to dynamic compression - which is the loss of linearity at high outputs.

The piezo tweeter is usually made with what is called a "bender" type piezo element. This is an element that moves by deforming its shape, bending. Sort of like imagining a coin that is flexible being held on the edge and pushed in the middle... but as it flexes, the diameter shifts as well. So, the bender element can not be held in a clamp. What they do is to sandwich the bender between a ring in the back and a small cone affixed to the center of the bender piezo element in the front and either use a compliant element to hold the front in place or else the flex in the cone itself to hold the thing in light compression.

The flexing of the piezo element is then transmitted via the cone to "phase plug" arrangement of sorts and then out through a horn...

There are expander piezo elements that *could* be set up to interface with a dome or in a true compression chamber, but since they are expensive and work best at ultrasonic frequencies I don't think anyone has made such a thing for commercial audio applications. Expanders move in one axis, like a regular speaker diaphragm does.

The way that the inexpensive piezo bender tweeter is made & works has many compromises that result in a rather non-linear speaker with relatively high distortions.

A compression driver is a type of driver - a generic term. It is not linked to a particular driver or means of generating the motion that creates the compression. Generally speaking what a compression driver does is to create a very strong but relatively small motion diaphragm excursion that is coupled via a phase plug (keeping the audio paths equal and in phase) to an acoustic impedance converter (a horn) that takes the very strong small motion and turns it into a large and much weaker motion (the output of the horn) and equalizes it for response over a wide bandwidth (as compared to the direct output of the compression driver it self in free air)

http://www.bearlabs.com -- Btw, I don't actually know anything, FYI -- every once in a while I say something that makes sense... ]
  Reply With Quote


Piezo compressionHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Compression ratio and diaphragm size in compression drivers inkasound Multi-Way 50 8th January 2009 03:38 PM
4" Seas long throw woofs, Motorola piezo compression drives, TangBand 2" widebands mr_ro_co Swap Meet 4 15th April 2008 01:16 AM
Piezo help shawn1972 Multi-Way 23 6th September 2007 07:09 AM
piezo switch? garbage Parts 5 31st July 2005 06:06 PM
Using piezo tweeters Rory Multi-Way 15 6th November 2001 08:46 PM

New To Site? Need Help?

All times are GMT. The time now is 10:27 AM.

Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio