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good books on amplifier construction

F

Fred Stevens

Jan 1, 1970
0
pil said:
I am interested in buying the following books:


PRACTICAL AUDIO AMPLIFIER CIRCUIT PROJECTS
Author : Andrew Singmin



HIGH-POWER AUDIO AMPLIFIER CONSTRUCTION MANUAL: 50 TO 500 WATTS FOR
THE AUDIO PERFECTIONIST
Author : G. Randy Slone; Randy Slone; Slone



Any comments on these books?

Which books would you recommend for a third year EE student who is very much
into amplifiers and sound? I am looking for a book which actually have
circuits that I can construct.

Thanks

Johan Wagener


Have a look at the book on Audio Ampifier design by Douglas Self. He
also has a website which you could find using Google.

Fred.
 
B

Ban

Jan 1, 1970
0
Ben said:
The Class D amps are certainly making many inroads in many consumer
products, but how fast it replaces analog power amplifiers remains to
be seen. For stereos sold at Wal-Mart, the transition may already be
100 percent, but I doubt you could find a 'Class D' amp in high-end
audio stores, or if so, that it sounds as good as any analog amplifier
in the store. Analog amps in that area (admittedly not a large
consumer market) will surely be around for a long time, unless Class D
amps show substantially more improvement over current state of the
art.
It's still an art to develop a digital amp. There is a company Tripath
http://www.tripath.com/ which has specialized in high quality digital amps.
They use a delta sigma approach with feedback directly from the output of
the switching stage. The results are really good sounding amps, satisfying
even high-end requirements.

Pulse width modulation is digital. It fulfills the basic requirements of
digital, which means quantized and time discreet. The output stage has only
2 states and the repetition of that switching follows a fixed time pattern.
If the width is continously variable or in steps doesn't make it analog. The
advantage of a digital output stage is the high efficiency and subsequently
much higher power you can achieve with the output devices. So the main
fields of application are in very high power amps or very small lowish
(0.5-2W) output stages for cellphones and PDAs. But I'm sure in future most
if not all amps will be working like this.
That (punse-width modulation) is the traditional Class D approach.
Some "Class D" amps work just like sigma-delta modulators in A/D
converters. The output is either a 1 or a 0, and the time is also
quantized: the output only changes states at specific times, at the
sample rate, which is very much higher than the audio range, usually
around 2 MHz. These have advantages over straight PWM, but with an odd
disadvantage that there can be significant delays (as in a few
milliseconds) between input and output.
The delays ocurr only with long digital FIR filters, not necessarily. The
output needs to be filtered as well, usually a L/C passive filter, which
adds a delay according to its minimum phase characteristic. With a second
order filter this delay is usually only a few(2-5) microseconds.

That was maybe 20yrs ago. It is still cutting edge technology, but since
Sony has introduced SACD with a fixed 2.8224MHz modulation, this argument is
totally bogus. It outperforms by far any CD quality. Sony offers all-digital
amps as well, which are optically coupled to the SACD-player, no analog in.
Sure there must be an analog output voltage because our ears work analog,
but this is done with that passive L/C lowpass mentioned before.

I'm currently designing a digital amp. It has analog inputs, and an analog
delta-sigma modulator, but then the signal is digitized and processed
digitally. Since this is not a commercial product, but for my own delight,
I'm willing to share my approach with anybody interested and can post the
schematics on ABSE when done. You can also drop me a mail to have a look at
the current state.
 
K

Karl Uppiano

Jan 1, 1970
0
That was maybe 20yrs ago. It is still cutting edge technology, but since
Sony has introduced SACD with a fixed 2.8224MHz modulation, this argument is
totally bogus. It outperforms by far any CD quality. Sony offers all-digital
amps as well, which are optically coupled to the SACD-player, no analog in.
Sure there must be an analog output voltage because our ears work analog,
but this is done with that passive L/C lowpass mentioned before.

There are many who would disagree that SACD is in any way superior to CD
audio. Several respected pioneers in digital audio believe that SACD is
fundamentally flawed; that it ignores some very fundamental principles
necessary for a high quality sampled data system. As far as my argument
being totally bogus, you'll have to explain that. Distortion figures for the
best class "D" amplifiers I've seen so far exceed the best linear amplifiers
by a factor of at least ten.
 
N

Neil Preston

Jan 1, 1970
0
The Class D amps are certainly making many inroads in many consumer
products, but how fast it replaces analog power amplifiers remains to
be seen. For stereos sold at Wal-Mart, the transition may already be
100 percent, but I doubt you could find a 'Class D' amp in high-end
audio stores, or if so, that it sounds as good as any analog amplifier
in the store. Analog amps in that area (admittedly not a large
consumer market) will surely be around for a long time, unless Class D
amps show substantially more improvement over current state of the
art.

Pro audio is wholeheartedly embracing the fully digital amplifier. Crown
Audio makes the CE4000 and other models that are fully digital, and Peavey
has been making digital amps since the '80s. I'm sure there are others.....

Neil Preston, CET
Preston Electronics, LLC
 
I

Ian Bell

Jan 1, 1970
0
Neil said:
Pro audio is wholeheartedly embracing the fully digital amplifier. Crown
Audio makes the CE4000 and other models that are fully digital, and Peavey
has been making digital amps since the '80s. I'm sure there are
others.....

Please define 'fully digital'

Ian
 
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