|
Copyright © 2009 through 2016 by Wayne Stegall
Audio Home Page
Circuits
or
calculations
should
not
be
breadboarded
until
they
are
proven
by
SPICE
simulation.
Even
then
breadboard
and
test
a
prototype
before
committing
to
a
final
circuit.
Unproven
circuits
or
ideas
are
for
mental
stimulation
only.
Note
also
that
mistakes
usually
go
unnoticed
until
I
find
and
fix
them;
therefore
I
recommend
letting
ideas
sit
for
a
while
before
considering
them
complete.
For this same reason I try to provide proofs where
reasonable or possible so that the user of an idea can
verify it before use.
First Things
Theory
- Phono Equalization Calculations
Updated February 6, 2014 .Added
schematic and design equations for op-amp based
current-input circuit. Updated March 17,
2014. Expanded derivation of two stage
equalization equations to more easily show how
current-input equalization derives from them.
Added more topologies and detail for current input
designs..
- When Is Phase Shift
not Phase Shift? January 2, 2009
- Linear Phase Sinc
Compensation Filter for Zero-Oversampling DACs
January 26,
2009
- Mathematical
Consideration of Some of the Limitations of Digital
Audio May 23, 2009
- Phono Termination
Calculations and Calculator August 10, 2009.
Updated September 13, 2012 Raised program
version to 3.3.0 adding shortcuts for entry of
Bessel and Butterworth Q values.
- Active Inductor Load
Updated March
11, 2010. Changed designation for MOSFET
constant to proper kn.
- Power Supply Ripple
Calculations and Capacitor Size December 6, 2009
- Simple Noise Calculations
Updated
February 27, 2010. Recalculated RIAA noise
bandwidth by numerical integral.
- Musical Feedback
Amplifiers Updated November 2, 2010. Added AD847 to list
of Possibly
Musical IC Operational Amplifiers and a link to its
datasheet.
- Simple DC Servos
Updated July
21, 2010. Spice verified. First order
servos reduce amplifier DC offset without fear of
oscillation. Musical Feedback Amplifier
example. Elaborated servo equations to
better clarify integrator response.
- A Musical View of
Distortion August 31, 2010
- Transfer Curve Shape
and Distortion
January 1, 2011. Multiple bends in transfer
functions reduce distortion quality. Updated
January 6,
2011. Added investigation into distortion
masking and
made
an immediate model correction to same.
- Flicker Noise
Calculations
January 26, 2011. Noise of unknown origin
causes a rise in noise at low frequencies.
- Managing TIM February 26,
2011. Practical means to avoid a
difficult-to-measure form of distortion.
- Distortion Cancelation May 26,
2011. Three simple distortion cancelation
concepts. Updated May 31, 2011.
Added SPICE verification of voltage mirrors. Updated June 8,
2011. Recommended use of voltage mirror for
BJT circuits only for unity gain pending further
investigation. SPICE results problematic with
gain, only unity gain producing the desired
results. See text. Updated June 11, 2011
Added SPICE verification of integer-gain BJT voltage
mirror.
- Optimizing the Class B
Emitter Follower August 5, 2011. Is current
drive better than voltage drive?
- Local Feedback August 27,
2011. Is Local Feedback the same concept as
Global Feedback? Updated September 26,
2022. Correct Compensated Phase Margin in
chart where values transposed.
- Apples and Oranges October 2,
2011. A simple proof that class-A and class-B
distortion specifications are not comparable.
- Phono Preamp Input
Protection November 3, 2011.
- Transistor
Preference December 14, 2011. The
effect of transistor choice on distortion
performance
- One-Bend
Amplifier January 31,
2012. Part
1: Compare a current-feedback
amplifier allowing a one-bend distortion
characteristic to its voltage-feedback
equivalent. Updated March 14,
2012 Added correction concerning output
stage transconductance factor and added a link to
the next article.
- Digital
Audio Formats April 18, 2012. Updated
April 19, 2012 Added graph illustrating how
oversampling improves analog filter
application. Updated April 20, 2012
Added extra material correcting presumptions
contrary to the limitations of the
successive-approximation ADC.
- Feedback
Distortion Analysis August 11,
2012. Taming the capricious transfer
curve. Updated August 11, 2012.
Added footnote about polynomial representation,
improved some wording, added derivation of gain
polynomial from transfer curve polynomial, and
added an example of long division.
- Understanding the S-Domain October
26, 2012.
Updated October 27, 2012. Added Q to
legend of figure 6 and another link under
examples.
- Delta-Sigma
Modulators
January 15, 2013. Their basic theory of
operation. Updated January 16, 2013.
Corrected some grammar and added an extra phrase
of text and graphs of analog FIR filter kernels.
- Single-slope
Safe-area
Limiter
March 16, 2013. And other transistor
limiters. Updated April 5, 2013.
Added an improved component calculation sequence
and additional power calculations.
- Electrical-Mechanical
Equivalence
April 27, 2013.
- Analog is
Digital
May 24, 2013. Quantum mechanics defines
quantization of analog signals comparable to
that of digital audio.
- Thermal
Design July 12, 2013. Part 1:
Thermal design for gainclone and one-bend
amplifiers is used to illustrate the presented
theory.
- Thermal
Design
August 17, 2013. Part 2:
Thermal design for one-bend amplifier is used to
illustrate theory advanced to include thermal
capacitance. August 23, 2016.
Restored missing subfile to SPICE model.
- Square Law September 17,
2013. How the square-law of field-effect
devices arises from physics.
- Room Effect and
Speaker Alignment December 6,
2013.
- Differential
Equalization
May 27, 2014. Differential circuit
transformation has application to differential
RIAA equalization.
- Perspective August 16,
2014. The mathematics of the perception of
acoustic distance and the possiblity of altering
it with equalization. Updated August 18,
2014. Corrected some misspellings and
grammar, improved some wording, and completed
footnote.
- Decibels November 21,
2014. The calculation and use of decibels
in audio.
- Noise
Shaping Music
April 3, 2015. DSD-like coding inside PCM
digital audio content increases its
resolution. Updated May 27, 2015.
Corrected equations 2 and 3 making pole only
dependent on b1; the a0
coefficient only affects gain. Updated
July 1, 2020 Added text to Final Remarks
better clarifying why high bit resolution
(32bit?) is desired in audio DACs...
- Digital Phono
Equalization
June 6, 2015. Updated September 1,
2015. Added capability to digitally
equalize a current-input preamplifier.
Updated September 7, 2015. Added results
of an actual test recording. Updated
May 3, 2016. Added inverse RIAA
functionality to software.
- Turntable Geometry October 26,
2015. Theory, calculator, and protractor
useful to setup your turntable's tonearm.
October 26, 2015. Added a more precise
statement about what software will print the
protractor. October 29, 2015. Added
explanation of overhang to the end of the theory
section. Updated November 14, 2015.
Added |φerr/r| graph to calculator to
give feedback that calculations are correct.
- Dual-slope
Integrator
January 16, 2016. Reduce high frequency
amplifier distortion.
- Lossy
Compression
February 27, 2016. How does compressed
audio like mp3 work and what effect does it have
on sound? Updated February 29, 2016. Added
time anomalies to Analysis of sound effect
- Butterworth
Filter Synthesis November 18,
2016. Updated November 25, 2016.
Added highpass bode plot and example of
calculation of pole angles and Qs.
- Chebychev
Filter Synthesis December 31,
2016.
- State Variable Tone
Control
July 14, 2017.
Application
- Line Level Class A
Power Supply Updated March 11,
2010. Corrected for improper gfs
presumptions.
- Low Noise
2-Stage All JFET Phono Preamp Updated July 2,
2010. SPICE verified. Recalculated
with 48V power supply and RIAA standard gain.
- A Linear Logarithmic Volume
Control September 29, 2010.
- Low-noise
Hybrid Op-amp/Discrete Phono Preamp
October 29,
2010. SPICE verified. Desire discrete
output buffer to add neutral euphony to nearly
distortionless op-amp preamp. Updated October
29, 2010 Improved visibility of graphs.
Updated October 30, 2010 Added links to
semiconductor datasheets in parts list. Move
class-a bias to connect to positive supply, and
verify no operational changes.
- Cascode
Selector
November
17, 2010.
SPICE
verified. Audiophile-grade
semiconductor selector for input or other
switching.
Updated
November 27, 2010.
Added power supply
recommendations and a schematic for an LED
indicator.
- Cascode Phono Preamplifiers May 3,
2011. SPICE verified. Capacitively
coupled cascode enables an easily adjustable
single-stage preamp. Updated March 3,
2012 Added transfer error curve analysis for
both circuits.
- One-Bend
Amplifier March 14, 2012.
Part 2:
Improving important details of a current-feedback
amplifier.
- One-Bend
Amplifier June 6, 2012. Part 3:
Modified circuit adds a predriver stage.
- Floating
Source-follower Regulator July 7,
2012. One-Bend Amplifier Part 4: Hum
injected in stage 2 of amplifier required the
design of a useful general purpose voltage
regulator. Updated July 8, 2012. Added
comment about the MOSFET's limited hum suppression
capability after equation 11.
- Warp Filter September 22,
2012. Highpass notch filtereliminates dangerous
LP warp signals.
- DAC Cascode December 1,
2012. Analog DAC circuit designed with one
BJT. Updated December 2, 2012.
Added text recalculating a new C4 value for the
second circuit under load. Updated December
7, 2012 Correcting SPICE model error changed
distortion results somewhat. Reworded
statement about useful DACs to indicate that the
AD1955 will require an NPN design. Added
paragraph on the interpretation of the
datasheet. Updated January 1, 2013.
Added an NPN design and analysis based on the
AD1955. Updated January 2, 2013.
Changed schematics to show how unused DAC outputs
should be terminated.
- Voice Control October 26,
2013. Circuit enables adjustable euphonic
control.
- Distortion
Grapher March 5, 2015. Circuit
enables distortion error to be graphed.
- One-Bend
Amplifier August 20, 2016. Part 4:
Improvements include lower hum
- Sealed-box Speaker
Equalizer January 14, 2017 Part 1:
Chebychev design methods allow the design of
speaker equalizer. Updated January 14, 2017
Added missing last curly brace not copied with
program and added mention of use of SPICE
Opus. Updated January 14, 2017 Added input for user to
input his own C1/C2 choice to program
- Sealed-box Speaker Equalizer March 18, 2017 Part 2:
Design of equalizer with n-channel JFETs.
Updated March 19, 2017. Corrected incorrect
filenames in program use instructions and added a
brief paragraph on buffer design. Updated
March 21, 2017. Added section Determining speaker
parameters.
- Input/Output Bypass Board February 6, 2018.
- One-Bend Amplifier May 15, 2018. Part 5: Set bias
for class B/AB and evaluate results.
- DIY Mogami Speaker Cables July 5,
2022. Coaxial speaker cables improve the sound
of my stereo.
.
.
Downloads
- CD Exerciser – Improve
your CD player with a homemade test disk April 20, 2009
- Op Amp Noise Calculator
Updated
January 17, 2011. Added considerable new
program functionality including accounting for
flicker noise.
- Phono Termination
Calculations and Calculator Details in Theory above.
- FETCurve June 26,
2011. A FET parameter calculator.
Updated May 31, 2012. Added SPICE
verification. Updated program to version
1.1.0 to flag alias error and to show kn
for transconductance factor to avoid confusion
with SPICE parameter KP. Updated June 2,
2012. Updated program to version 1.2.0
adding input checking for numeric entries.
Immediatedly released version 1.2.1 to allow
negative number entry.
- Turntable Geometry Theory, calculator,
and protractor useful to setup your turntable's
tonearm. Details in Theory above.
Obsolete
External Links
- Affordable$$Audio Internet audio
magazine archives, just merged into HiFi Zine
below (subjectivist, some advertising)
- Audiophilia Internet audio
magazine (subjectivist, some advertising)
- AudioWorld
Web Directory This website has reverted to an
Audio Web Directory again for now.
- AudioXpress Website of
print audio magazine emphasizing DIY
(subjectivist/objectivist, some articles on
website)
- Enjoy the Music Internet audio
magazine (subjectivist, some advertising)
- High-end
Audio
The personal audio website of Arthur Salvatore
(subjectivist, no advertising).
- High
Fidelity Internet audio
magazine (subjectivist, some advertising)
- Hi-Fi
Choice Website of print audio
magazine (subjectivist/objectivist,
some articles
on website)
- Hi-Fi News
& Record Review
Website of print audio
magazine (subjectivist,
some articles
on website)
- HiFi Zine Independent
internet audio magazine (philosophy?, some
non-audio ads)
- Positive
Feedback Internet audio
magazine (subjectivist, some advertising)
- Six
Moons
Internet audio magazine (subjectivist, some
advertising)
- SoundStage!
HiFi
Internet
audio magazine (subjectivist, some advertising)
- Stereophile Website of print audio
magazine (subjectivist,
some articles
on website)
- Stereo
Times
Internet
audio magazine (subjectivist, some advertising)
- TNT-Audio Independent
internet audio magazine (subjectivist, no
advertising)
- Ultra High
Fidelity Magazine
Website of print audio
magazine (subjectivist,
interesting
general hifi reading on website, but no magazine
articles)
|
|