[Roko]

Hi all,


I'm new here, and for starters I have a really noobish question:

Why exactly is it impossible to connect HiFi Speakers to a computer (except because of the fact that they don't have a mini-jack plug (at least mine don't) )?

I know it's possible to connect a computer to a HiFi system (by plugging it into "Line In"/"AUX"), but I would like to be able to do it without the Hi-Fi system, only with the speakers.

I guess what I really want to know is what kind of a 'converter' is there inside the Hi-Fi system..? Does it modify the signal from the computer, or is it merely a small circuit just adapting the amperage/voltage/impedance/whatever..?


Thanks in advance

[ShadowTek]

On 2010-02-12, Roko wrote:

Hi all,


I'm new here, and for starters I have a really noobish question:

Why exactly is it impossible to connect HiFi Speakers to a computer
(except because of the fact that they don't have a mini-jack plug
(at least mine don't) )?

I know it's possible to connect a computer to a HiFi system (by
plugging it into "Line In"/"AUX"), but I would like to be able to do it
without the Hi-Fi system, only with the speakers.

I guess what I really want to know is what kind of a 'converter' is
there inside the Hi-Fi system..?

The main value of your receiver is that it has an amplifier inside of
it, which allow you to send a respectable amount of power to the
speakers. As you may have seen before, some PC speakers *do* plug right
into the computer's audio output jack, but they aren't very good/powerful
speakers, since they aren't getting enough juice to really do anything.

[Dave Platt]

Hi all,

I'm new here, and for starters I have a really noobish question:

Why exactly is it impossible to connect HiFi Speakers to a computer
(except because of the fact that they don't have a mini-jack plug
(at least mine don't) )?

Well, it isn't impossible. In most cases, though, you won't get
enough sound to be useful.

Loudspeakers require that a significant amount of power be delivered
to the drivers (the "speakers" themselves mounted in the cabinet) in
order to create a useful amount of sound. Typically, a HiFi speaker
is driven by an amplifier that can deliver a maximum of tens to
hundreds of watts. For most hi-fi speakers, average listening levels
run in the range of a few watts. Speakers have a relatively low
"impedance" (measured in ohms)... this means that they draw a fairly
large amount of current for any given amount of voltage. 8-ohm
speakers are quite typical. Stereo receivers and amplifiers are
designed to drive these low impedances, with enough voltage and
current to deliver their rated power.

Most computer sound-card outputs do *not* include a speaker amplifier.
They aren't designed to deliver large amounts of power, or to drive
low impedances. They are typically designed to drive efficient
headphones (drawing a fraction of a watt, at impedances of 32 ohms on
up), or to drive "line-level" devices (amplifier inputs or
"self-powered" computer loudspeakers, drawing a tiny fraction of a
watt with impedances of thousands of ohms).

In short, computer sound-card outputs are "wimpy" - they don't have
strong enough electronic "muscles" to deliver the power needed to move
a heavy loudspaker driver's cone back and forth to make sound.

Many computer loudspeakers have built-in power amplifiers, required to
boost the line-level signal and drive the computer speaker properly.

Most hi-fi loudspeakers do *not* have a built-in amplifier... there
are some exceptions, but most do not.

I know it's possible to connect a computer to a HiFi system (by
plugging it into "Line In"/"AUX"), but I would like to be able to do it
without the Hi-Fi system, only with the speakers.

To do that, you'd need one of two things:

- A hi-fi speaker with a built-in amplifier (they do exist), or

- A new computer sound-card with a built-in speaker-level power
amplifier. Once again, these do exist, but they're not very common,
and typically can't deliver more than a couple of watts per
channel.

I guess what I really want to know is what kind of a 'converter' is
there inside the Hi-Fi system..? Does it modify the signal from the
computer, or is it merely a small circuit just adapting the
amperage/voltage/impedance/whatever..?

It's an active amplification stage (or several stages). It takes an
incoming signal with only a few milliwatts of power (a typical
line-level signal is 2 volts peak-to-peak into 5k ohms or so, which is
less than a thousanth of an ampere), boosts the voltage upwards by a
factor of 10 or more, and is capable of driving the speakers with
currents of several amperes. In short, the amplifier is delivering
thousands of times more power to the speaker, than it's taking in from
the computer's sound-card output.

The signal coming out of the amplifier looks like a "big brother" of
the signal going in... the waveform should have the same shape (if it
doesn't, the amp is distorting it) but it's larger in both voltage and
current.

The additional power is drawn from the building's AC power mains. Not
all of the power pulled from the mains ends up going to the speaker...
there's a significant amount of waste in most amplifier designs, and
this ends up being dissipated as the heat which warms up the amp.

--
Dave Platt AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

[Roko]

wow... thank you all for your replies, you've definitely answered all of my questions.
I have new ones now, of course

So this means I would be able to connect the HiFi speakers to the computer if I had an amplifier (of satisfactory quality) which would be put between the two? Of course, that would require some necessary tweaks and I would actually end up building a receiver? And another of course: if not building a brand new amplifier from the very beginning, I would have gotten it from another HiFi receiver, and that again would make no sense doing because the amplifier, as ShadowTek said, is the main value of a receiver and then I could have just as well connected the speakers through the existing receiver?
Sooo, if the answers to the above questions are all "yes", the only sane thing to do is to buy a new HiFi receiver - that would actually prove to be the cheapest solution then?

Once again, thank you all for your time and patience

[David Nebenzahl]

On 2/13/2010 2:13 PM Roko spake thus:

wow... thank you all for your replies, you've definitely answered all of
my questions.
I have new ones now, of course

So this means I would be able to connect the HiFi speakers to the
computer if I had an amplifier (of satisfactory quality) which would be
put between the two? Of course, that would require some necessary tweaks
and I would actually end up building a receiver? And another of course:
if not building a brand new amplifier from the very beginning, I would
have gotten it from another HiFi receiver, and that again would make no
sense doing because the amplifier, as ShadowTek said, is the main value
of a receiver and then I could have just as well connected the speakers
through the existing receiver?
Sooo, if the answers to the above questions are all "yes", the only
sane thing to do is to buy a new HiFi receiver - that would actually
prove to be the cheapest solution then?

Yes. You're waaaaay overthinking this.

My computer is connected to my old receiver (bought used in 1975), which
provides more than adequate sound both in terms of volume and quality.
The line-level connections (line in and line out) are pretty standard
between computer sound cards and audio equipment.

Used audio receivers of sufficient quality for what you want to do are a
dime a dozen. Often you can scavenge them for free.

You don't need to "build" anything (well, except maybe a cabinet or
shelf to hold this stuff).


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[geoff]

Roko wrote:
So this means I would be able to connect the HiFi speakers to the
computer if I had an amplifier (of satisfactory quality) which would
be put between the two? Of course, that would require some necessary
tweaks and I would actually end up building a receiver? And another
of course: if not building a brand new amplifier from the very
beginning, I would have gotten it from another HiFi receiver, and
that again would make no sense doing because the amplifier, as
ShadowTek said, is the main value of a receiver and then I could have
just as well connected the speakers through the existing receiver?
Sooo, if the answers to the above questions are all "yes", the only
sane thing to do is to buy a new HiFi receiver - that would actually
prove to be the cheapest solution then?

Once again, thank you all for your time and patience

Yep a new hi-fi amplifier (commonly confusingly misnamed 'receiver'), or
your old one if physically close to your computer.


geoff

[David Nebenzahl]

On 2/13/2010 10:17 PM geoff spake thus:

Roko wrote:

So this means I would be able to connect the HiFi speakers to the
computer if I had an amplifier (of satisfactory quality) which would
be put between the two? Of course, that would require some necessary
tweaks and I would actually end up building a receiver? And another
of course: if not building a brand new amplifier from the very
beginning, I would have gotten it from another HiFi receiver, and
that again would make no sense doing because the amplifier, as
ShadowTek said, is the main value of a receiver and then I could have
just as well connected the speakers through the existing receiver?
Sooo, if the answers to the above questions are all "yes", the only
sane thing to do is to buy a new HiFi receiver - that would actually
prove to be the cheapest solution then?

Yep a new hi-fi amplifier (commonly confusingly misnamed 'receiver'), or
your old one if physically close to your computer.

Hmm; misnamed? Dunno which side of the Atlantic you're on, but over here
('Merkin), a receiver is an amplifier + tuner, to distinguish it from an
amplifier, which normally lacks a tuner. (And of course, speaking of
confusion, the amplifier actually consists of a preamplifier + a power
amplifier, which are sometimes separate things ...)


--
You were wrong, and I'm man enough to admit it.

- a Usenet "apology"

[Mr.T]

"David Nebenzahl" wrote in message
.com...
Hmm; misnamed? Dunno which side of the Atlantic you're on, but over here
('Merkin), a receiver is an amplifier + tuner, to distinguish it from an
amplifier, which normally lacks a tuner. (And of course, speaking of
confusion, the amplifier actually consists of a preamplifier + a power
amplifier, which are sometimes separate things ...)

And a pre+power amplifier in one box is commonly called an integrated
amplifier for that reason, and a separate pre-amp or power amp are almost
always named as such.
Just to add to your list, a phono pre-amp may be separate as well, and a
moving coil cartridge pre-amp is sometimes called a pre-preamp.

MrT.

[Roko]

OK, since my mother tongue is not English (of any "kind", no matter what side of any ocean from) and since I'm a noob when it comes to HiFi, help me understand this:

Picture 1: http://www.audio-video.com.hr/img/pr...wood/6300s.jpg - a HiFi *receiver*? (which I referred to as a "HiFi system" in my first post up there. (a "HiFi system" would be a receiver+speakers?))

Picture 2: http://www.quasarelectronics.com/ima...c-kit/3050.jpg - a HiFi *amplifier*?
You say I could get one of these easily, and for a fair price? Would it be everything I needed if I just wanted to connect passive speakers (which I already have) to the computer?

[geoff]

Roko wrote:
Hi all,


I'm new here, and for starters I have a really noobish question:

Why exactly is it impossible to connect HiFi Speakers to a computer
(except because of the fact that they don't have a mini-jack plug
(at least mine don't) )?

It isn 't impossible, but you won't hear much.


I know it's possible to connect a computer to a HiFi system (by
plugging it into "Line In"/"AUX"), but I would like to be able to do
it without the Hi-Fi system, only with the speakers.

The 'hi-fi system' includes an amplifier, which is necessary to provide
sufficient power to make the speakers sound liud enough.


I guess what I really want to know is what kind of a 'converter' is
there inside the Hi-Fi system..? Does it modify the signal from the
computer, or is it merely a small circuit just adapting the
amperage/voltage/impedance/whatever..?


It amplifies the signal from a computer, CD, Tuner, DVD, turntable,
whatever, to enable the sound to be heard from speakers.


geoff

[Arny Krueger]

"Roko" wrote in message

Hi all,


I'm new here, and for starters I have a really noobish
question:

Why exactly is it impossible to connect HiFi Speakers to
a computer (except because of the fact that they don't
have a mini-jack plug (at least mine don't) )?

Most computer sound cards are designed to drive headphones and speakers with
their own power amplifiers built into them.

I know it's possible to connect a computer to a HiFi
system (by plugging it into "Line In"/"AUX"), but I would
like to be able to do it without the Hi-Fi system, only
with the speakers.

This won't be sucessful.

I guess what I really want to know is what kind of a
'converter' is there inside the Hi-Fi system..?

The "converter" is called a power amplifier.

Does it
modify the signal from the computer, or is it merely a
small circuit just adapting the
amperage/voltage/impedance/whatever..?

These things vary, but at the minimum they are fair-sized circuits that
adapt the amperage/voltage/impedance, as you put it. Their size is
nontrivial because of the power levels that are involved.

It turns out that most desktop PCs have fairly healthy internal 12 volt DC
power sources that have considerable reserves. Power amplifiers of the kind
that are used with automotive sound systems (which are designed for 14.7
volt power) can be adapted to exploit this source of power.

[Mr.T]

"Arny Krueger" wrote in message
...
Most computer sound cards are designed to drive headphones and speakers
with
their own power amplifiers built into them.

In fact not very many headphones have power amps built in, but many computer
soundcards can drive 32 ohm headphones directly.
However you are correct for speakers.

MrT.