[AMBROSE]

I posted the previous ? " how to built a dolby system ? " .The answer
was good.

So I can't built a dolby system without license from DOLBY inc . If so
can I built a 3d surround sound system amp that can support 4 speakers
of 400watts capacity .

Can anyone help me out how to built a 3D suround sound system from
scratch?

[Richard Crowley]

"AMBROSE" wrote ...
I posted the previous ? " how to built a dolby system ? " .The answer
was good.

So I can't built a dolby system without license from DOLBY inc . If so
can I built a 3d surround sound system amp that can support 4 speakers
of 400watts capacity .

Can anyone help me out how to built a 3D suround sound system from
scratch?

Again, what do YOU mean by "3D surround system"
And what do you mean by "from scratch"?

Preamp/controller/decoder? (Already discussed problem with "decoder")
Power amp(s)?
Speakers?
Just system integration with store-bought components?

If you don't precisely define what you are asking, you are
unlikely to get the answers you want.

[Richard Crowley]

"Richard Crowley" wrote ...
"AMBROSE" wrote ...
I posted the previous ? " how to built a dolby system ? " .The answer
was good.

So I can't built a dolby system without license from DOLBY inc . If so
can I built a 3d surround sound system amp that can support 4 speakers
of 400watts capacity .

Can anyone help me out how to built a 3D suround sound system from
scratch?

Again, what do YOU mean by "3D surround system"
And what do you mean by "from scratch"?

Preamp/controller/decoder? (Already discussed problem with "decoder")
Power amp(s)?
Speakers?
Just system integration with store-bought components?

If you don't precisely define what you are asking, you are
unlikely to get the answers you want.


If you are just asking about constructing a power amplifier,
can we assume that you mean 4 channels of 100 watts each?
What is your level of electronics construction experience?
There are various ways of doing this with varying degrees
of "from scratch". And what is your proposed budget?

[Dave Platt]

I posted the previous ? " how to built a dolby system ? " .The answer
was good.

So I can't built a dolby system without license from DOLBY inc . If so
can I built a 3d surround sound system amp that can support 4 speakers
of 400watts capacity .

Can anyone help me out how to built a 3D suround sound system from
scratch?

There are a number of things you can do without a license, which will
help create more realistic stereo ambiance using a multi-speaker
system. One or another of them may suit you.

The simplest is to implement the old "Dynaquad" system. This is a
method for hooking up four (identical) loudspeakers, in a
left/center-front/right/center-rear arrangement. It can be done using
just a normal stereo amplifier... it's a passive difference-extraction
system. Google around a bit and you'll surely find a page which shows
how it's hooked up.

A slightly more complex approach is to build a two-channel-in,
four-channel-out amplifier, and include the equivalent of the Dynaquad
summing/differencing logic prior to the amplifier section... using a
handful of high-quality op amps and some passive components would be
the way to go. This would give you a bit more leeway with your
loudspeaker selection, as the speakers might not need to be physically
and electrically identical. You could also include a line-level
low-pass/high-pass crossover system, moving the low bass out of the
left/center/right channel pathway and driving a separate subwoofer.

An even fancier approach is to take the two incoming signals, and
implement the ambience extraction (differencing) and even ambience
simulation (time delay and echo emulation) via time-delay electronics.
The old a/d/s ambience extraction system, and I believe some of the
earlier Yamaha models, used analog charge-coupled "bucket brigade"
chips. Newer systems will digitize the analog data, feed it to a DSP,
have the DSP do all of the signal mixing/processing via digital math
and a bucket of memory to hold the samples, and then reconvert to
analog using DAC chips and amplify the resulting analog signals for
the speakers.

There's probably an order of magnitude difference in difficulty
between the first approach (for which you can use a stereo amplifier
you already have) and the second (in which you actually build a
four-channel amp plus some analog circuitry). The third approach is
probably an order-of-magnitude more work than that.

As to the amplifier stages themselves... there's six boatloads of DIY
amp designs out there. The Leach amplifier design is well thought
of... it's a fairly traditional Class AB linear amp, capable of
excellent performance.

If you want something slightly more shrink-wrapped, you can buy power
amplifier modules (drivers, power transistors, and heatsinks) from
Marchand (www.marchandelec.com) and wire them up with a power supply
of your own construction. The Marchand modules can generally be
bought as complete kits, or fully assembled and tested.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
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