Design Review Presentation - PowerPoint PPT Presentation

Senior design may06 01 headphone amplifier equalizer and sound stage l.jpg
Download
1 / 41

Senior Design May06-01: Headphone Amplifier, Equalizer, and Sound Stage Design Review Presentation Project Team Information Team Members Brandon BohlenEE Cory NelsonEE Tom ChenowethEE Travis FastEE Clients John Lamont Ralph Patterson III Presentation Outline

Related searches for Design Review Presentation

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Download Presentation

Design Review Presentation

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Senior design may06 01 headphone amplifier equalizer and sound stage l.jpg

Senior Design May06-01:

Headphone Amplifier, Equalizer, and Sound Stage

Design Review Presentation


Project team information l.jpg

Project Team Information

Team Members

Brandon BohlenEE

Cory NelsonEE

Tom ChenowethEE

Travis FastEE

Clients

John Lamont

Ralph Patterson III


Presentation outline l.jpg

Presentation Outline

  • List of definitions

  • Problem statement and proposed approach

  • Operating environment

  • Intended user(s) and use(s)

  • Assumptions and limitations

  • End product

  • Approaches considered and used


Presentation outline cont l.jpg

Presentation outline cont.

Accomplishments

Schedules and hours worked

Resource requirements and project costs

Project evaluation

Lessons learned

Risk and risk management

Closing statements


Acknowledgements l.jpg

Acknowledgements

Professors Lamont and Patterson III for their time and continued advice throughout the year

Ken Uhlenkamp for his work with the power supply

Jason Boyd for his help with the PCB layout


List of definitions l.jpg

List of Definitions

  • Audiophile – a person who is enthusiastic about high-fidelity sound reproduction.

  • mp3 – an audio compression format used for the playback of digital audio in home computers and portable devices.

  • PCB – a printed circuit board is an insulated board containing conductive strips that connect components into a compact circuit.

  • Sound stage – a circuit that simulates three-dimensional sound reproduction for headphone listening. The purpose of this circuit is to provide the user with an aural experience that sounds more like listening to two loudspeakers in a small room, rather than the typical binaural headphone experience.


Problem statement l.jpg

Problem statement

  • Design an amplifier for portable audio devices that has a 3-band equalizer, sound stage simulation and balance control built in for an enhanced user experience.


Proposed approach l.jpg

Proposed approach

  • Research, test, and analyze results for multiple circuits and decide the optimal circuit combination to meet the client’s requirements.


Operating environment l.jpg

Operating environment

Intended mainly for desktop use

Car compatible

Sustains a wide temperature range

-30o F to 120o F

Susceptible to random vibration

Not intended for mobile use

7.75” x 6.3” x 2.5”


Intended user s and use s l.jpg

Intended User(s) and Use(s)

  • General public

    • Specifically audiophiles

  • Use in conjunction with a portable audio source, such as a CD or MP3 player


Assumptions l.jpg

Assumptions

  • Product will drive headphones or self-powered speakers

  • Must at least have a 3-band EQ with ±20dB amplification

  • A battery supply that has a voltage rating of ±4.5 V

  • Product must run for a minimum of 8 hours

  • End product must stay under $150


Limitations l.jpg

Limitations

  • The system must at a minimum include:

    • 3.5 mm input jack

    • Two headphone jacks

      • one 3.5 mm (1/8” mini)

      • one 6.5 mm (1/4”)

    • Volume control

    • Balance control

    • Power switch and LED indicator

    • 3-band equalizer controls

    • Sound stage by-pass switch indicator

    • Labels for all controls


End product l.jpg

End Product

  • A completely encased prototype of a portable audio device capable of driving a set of high-fidelity headphones with a sound stage offering the user the ability to adjust a 5-band equalizer


Approach considerations l.jpg

Approach considerations


Approach used l.jpg

Approach used

There are five product components

Preamplifier

Balance control

5-band equalizer

Sound stage

Power amplifier


Preamplifier l.jpg

Preamplifier

  • Gain of 10 dB

  • High-pass filter implementation

    • Reduces noise

  • Dual in-line packages

    • Reduces size


Balance l.jpg

Balance

  • One channel can be completely cut while the other channel remains constant


Equalizer l.jpg

Equalizer

Three different equalizers were built and tested

Baxandall

Resonant frequency

Graphic equalizer


Baxandall equalizer l.jpg

Baxandall equalizer

  • Circuit used in last year’s amplifier project

  • Could not modify into 5-band equalizer


Resonant frequency equalizer l.jpg

Resonant frequency equalizer

  • Capable of having 5-bands

  • Never could get to work as desired


Graphic equalizer l.jpg

Graphic equalizer

Best of both worlds

Passive LC filter network

Only one op-amp per channel

Controllable Q and center frequencies

Problems

Inductors required for audio frequencies were not practical for this project (large, heavy)


Graphic equalizer23 l.jpg

Graphic equalizer

Solution: simulate induction using gyrators to invert the phase properties of a capacitor

Allows for any inductance value to be realized for the filters

Added quiescent current draw of each gyrator

Best compromise based on current draw vs. performance


Graphic equalizer24 l.jpg

Graphic equalizer


Sound stage l.jpg

Sound stage

Loudspeaker emulation

Time-delay

Cross-feed


Sound stage26 l.jpg

Sound stage

Two sound stage circuits were considered

Ohman cross-feed

Brungart

Pinna filter

Time-delay


Ohman cross feed l.jpg

Ohman cross-feed

  • Passive style cross-feed with time delay

    • Saves on current draw

  • Time delay set to be variable with maximum of 300 μs delay.


Brungart sound stage l.jpg

Brungart sound stage

  • Time-delay

    • Fourth order Bessel 150us time-delay

  • Pinna-related filter circuit

    • Mimics ear canal resonance curves

  • Cross-feed

    • Buffer, current-adder


Brungart sound stage29 l.jpg

Brungart sound stage

  • Sound stage was tested for audio qualities


Brungart sound stage30 l.jpg

Brungart sound stage

  • Pinna-related filter wasn’t considered aurally pleasing

  • Sound stage implemented with only the time-delay circuits


Power amplifier l.jpg

Power amplifier

  • Similar to pre-amp

  • Available gain of 20 dB


Accomplishments l.jpg

Accomplishments

  • Researched, tested and chose circuits to use in final product

  • Ordered casing and parts

  • Created final circuit on breadboard


Schedule l.jpg

Schedule


Hours l.jpg

Hours


Resources required l.jpg

Resources required


Project costs l.jpg

Project costs


Project evaluation l.jpg

Project evaluation

Project completed successfully

Design requirements were met

Cost exceeded requirements, but was deemed acceptable

Within size limitations

Provides user with a unique listening experience


Lessons learned l.jpg

Lessons learned

  • Gained knowledge about audio schematics

  • The importance of decoupling the audio signal

  • Have backup circuit choices

  • Importance of breadboard testing vs. PSpice simulations


Risk and risk management l.jpg

Risk and risk management

Anticipated

Loss of a team member

Circuit inadequacies

Many circuits were tested

All circuits were listened to in breadboarding

Unanticipated

Out of stock or discontinued parts

Different packages were ordered


Closing summary l.jpg

Closing summary

  • Problem

    • Design an amplifier for portable audio devices that has a 5-band equalizer, sound stage simulation and balance control built in for an enhanced user experience.

  • Solution

    • Designed and built a functional prototype that includes an amplifier, equalizer, sound stage simulator and balance control.


Questions l.jpg

Questions?


  • Login