mp3 player output volumes
 

Hi all, never posted in here before but seems you might be able to
help.

I'm looking for an MP3 player to use with an FM transmitter in my car
and occasionally an external speaker via the earphone socket.

Not headphones.

Both of the aforementioned devices benefit from a player with a high
output volume.

I've asked elsewhere but keep getting told that some headphones are
more efficient than others even though I clearly stated that I do NOT
want to use the player with headphones.

I'm also aware that some players have a switchable volume level.

I have tied a Sandisk, Creative and a Sony. None seem to go as loud as
my daughter's 3rd gen ipod. Trouble is I hate iTunes with a passion.

I've got a large mp3 library and don't want to re-record at higher
levels.

So, any websites that have reviews that include output level info?
Anyone got any ideas for players with a reputation for a decent
output?


TIA
--

blackbat /\x/\

mp3 player output volumes
 

I wonder what the output of these devices is supposed to drive, impedance
wise? I know they all vary, but into different phones, they do not all seem
to vary by the same amount, which leads me to think, that like many other
portable devices, they are sensitive to what they are driving, and not
always in a good way.


Of course some have that awful sounding ear protection limiter, which from
what I hear is designed to make the device sound so bad, you have to turn it
down!

Brian

--
Brian Gaff -
Note:- In order to reduce spam, any email without 'Brian Gaff'
in the display name may be lost.
Blind user, so no pictures please!
"blackbat" wrote in message
...
Hi all, never posted in here before but seems you might be able to
help.

I'm looking for an MP3 player to use with an FM transmitter in my car
and occasionally an external speaker via the earphone socket.

Not headphones.

Both of the aforementioned devices benefit from a player with a high
output volume.

I've asked elsewhere but keep getting told that some headphones are
more efficient than others even though I clearly stated that I do NOT
want to use the player with headphones.

I'm also aware that some players have a switchable volume level.

I have tied a Sandisk, Creative and a Sony. None seem to go as loud as
my daughter's 3rd gen ipod. Trouble is I hate iTunes with a passion.

I've got a large mp3 library and don't want to re-record at higher
levels.

So, any websites that have reviews that include output level info?
Anyone got any ideas for players with a reputation for a decent
output?


TIA
--

blackbat /\x/\

mp3 player output volumes
 

On Sat, 30 Jan 2010 16:53:21 +0000, blackbat
wrote:

Hi all, never posted in here before but seems you might be able to
help.

I'm looking for an MP3 player to use with an FM transmitter in my car
and occasionally an external speaker via the earphone socket.

Not headphones.

Both of the aforementioned devices benefit from a player with a high
output volume.

I've asked elsewhere but keep getting told that some headphones are
more efficient than others even though I clearly stated that I do NOT
want to use the player with headphones.

I'm also aware that some players have a switchable volume level.

I have tied a Sandisk, Creative and a Sony. None seem to go as loud as
my daughter's 3rd gen ipod. Trouble is I hate iTunes with a passion.

I've got a large mp3 library and don't want to re-record at higher
levels.

So, any websites that have reviews that include output level info?
Anyone got any ideas for players with a reputation for a decent
output?



As you are going to be using it with an external amplifier - whether
that is an FM transmitter or an external speaker, presumably via an
amplifier - the volume should not really be an issue. You just adjust
for the right level. Anything should be able to do that.

I have a Tomtom sat nav that stores MP3s on an SD card, and plays them
via the car's FM radio. That seems to work very well, and I imagine
that people in the surrounding cars can enjoy it too.

d

mp3 player output volumes
 

On Sat, 30 Jan 2010 17:10:08 GMT, "Brian Gaff"
wrote:

I wonder what the output of these devices is supposed to drive, impedance
wise? I know they all vary, but into different phones, they do not all seem
to vary by the same amount, which leads me to think, that like many other
portable devices, they are sensitive to what they are driving, and not
always in a good way.

Possibly.


Of course some have that awful sounding ear protection limiter, which from
what I hear is designed to make the device sound so bad, you have to turn it
down!

Or off, which most people seem to do.
--

blackbat /\x/\

mp3 player output volumes
 

On Sat, 30 Jan 2010 17:10:54 GMT, (Don Pearce) wrote:


As you are going to be using it with an external amplifier - whether
that is an FM transmitter or an external speaker, presumably via an
amplifier - the volume should not really be an issue. You just adjust
for the right level. Anything should be able to do that.
Not in my case. The FM transmitter is set to its max volume and so is
the speaker.
The speaker is a great little device by the way...
http://tinyurl.com/yd2m5x6




I have a Tomtom sat nav that stores MP3s on an SD card, and plays them
via the car's FM radio. That seems to work very well, and I imagine
that people in the surrounding cars can enjoy it too.
hee hee.

--

blackbat /\x/\

mp3 player output volumes
 

"Brian Gaff" wrote in message
om...

I wonder what the output of these devices is supposed to drive, impedance
wise?

Most headphones for portable players are 32 ohm.

David.

mp3 player output volumes
 

"blackbat" wrote in message
...
Hi all, never posted in here before but seems you might be able
to
help.

I'm looking for an MP3 player to use with an FM transmitter in
my car
and occasionally an external speaker via the earphone socket.

Not headphones.

Both of the aforementioned devices benefit from a player with a
high
output volume.

I've asked elsewhere but keep getting told that some headphones
are
more efficient than others even though I clearly stated that I
do NOT
want to use the player with headphones.

I'm also aware that some players have a switchable volume
level.

I have tied a Sandisk, Creative and a Sony. None seem to go as
loud as
my daughter's 3rd gen ipod. Trouble is I hate iTunes with a
passion.

I've got a large mp3 library and don't want to re-record at
higher
levels.

So, any websites that have reviews that include output level
info?
Anyone got any ideas for players with a reputation for a decent
output?



Why hate iTunes? You don't have to use it to buy anything but
it really is quite good at managing the contents of an iPod.



--
Woody

harrogate three at ntlworld dot com

mp3 player output volumes
 

On Sat, 30 Jan 2010 18:52:57 -0000, "Woody"
wrote:

Why hate iTunes? You don't have to use it to buy anything but
it really is quite good at managing the contents of an iPod.

I know some people like it.

I guess I can't see what could be easier than dragging and dropping in
Windows. Simply using my mp3 player in the style of a memory stick.

I've got a thing about bloating my PC with unnecessary proprietary
software.

And (apart from my volume problem) I can't see that an ipod is worth
twice the price of a Sony.
--

blackbat /\x/\

mp3 player output volumes
 

On Sat, 30 Jan 2010 18:52:57 -0000, "Woody"
wrote:

Why hate iTunes? You don't have to use it to buy anything but
it really is quite good at managing the contents of an iPod.

If I can't hear something on Spotify for free, iTunes at 69p is a
pretty good deal!

But I wouldn't want an iPod. I want to see the device as an simple
external drive, and be in complete control of how I copy music to and
from it. That means choosing just about anything EXCEPT an iPod.

mp3 player output volumes
 

google program "mp3gain"

mp3 player output volumes
 

On Sat, 30 Jan 2010 19:29:28 +0000, Laurence Payne
wrote:

I want to see the device as an simple
external drive

Exactly
--

blackbat /\x/\

mp3 player output volumes
 

In article , blackbat
wrote:
On Sat, 30 Jan 2010 18:52:57 -0000, "Woody"
wrote:

Why hate iTunes? You don't have to use it to buy anything but it
really is quite good at managing the contents of an iPod.

I know some people like it.

I guess I can't see what could be easier than dragging and dropping in
Windows. Simply using my mp3 player in the style of a memory stick.

I've got a thing about bloating my PC with unnecessary proprietary
software.

ahem Too late to worry about that if you are already using Windows. 8-]

More seriously, if you can't find an mp3 player that outputs a high enough
level then you could experiment as follows. (Assuming you are happy to
solder leads, etc.)

Buy a couple of the small signal transformers sold by CPC or similar. Try
using those to step up the output from the player. I have no idea if that
will work, but may be worth a punt if all else fails.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

mp3 player output volumes
 

On 30/01/2010 19:10, blackbat wrote:
On Sat, 30 Jan 2010 18:52:57 -0000, "Woody"
wrote:

Why hate iTunes? You don't have to use it tobuy anything but
it really is quite good at managing the contents of an iPod.

I know some people like it.

I guess I can't see what could be easier than dragging and dropping in
Windows. Simply using my mp3 player in the style of a memory stick.

I've got a thing about bloating my PC with unnecessary proprietary
software.

The iPod is also bloated then, doubt you actually will use playlists,
genius or their genre library management features.

Why not remove the Apple firmware and install rockbox?

http://www.rockbox.org

Then you can drag and drop to your hearts content :-)

--
Adrian C

mp3 player output volumes
 

In article ,
David Looser wrote:
"Brian Gaff" wrote in message
om...

I wonder what the output of these devices is supposed to drive, impedance
wise?

Most headphones for portable players are 32 ohm.

Yup. And capable of driving to a true line level - although perhaps not
with the same sort of headroom as pro gear.

--
*Be more or less specific *

Dave Plowman London SW
To e-mail, change noise into sound.

mp3 player output volumes
 

On 31/01/2010 14:58, Dave Plowman (News) wrote:
In ,
David wrote:
"Brian wrote in message
om...

I wonder what the output of these devices is supposed to drive, impedance
wise?

Most headphones for portable players are 32 ohm.

Yup. And capable of driving to a true line level - although perhaps not
with the same sort of headroom as pro gear.


That 'line level' drive out of the earphone socket is usually with the
players volume control straining at the limit, and probably over the
limit that is judged safe to let loose on young ears. So not many
players make those levels connected that way. It's also hissy.

I much prefer using real line level connections (as with Apple)
available at the docking connector.

--
Adrian C

mp3 player output volumes
 

On Sun, 31 Jan 2010 13:51:57 +0000, Adrian C
wrote:


The iPod is also bloated then, doubt you actually will use playlists,
genius or their genre library management features.

Why not remove the Apple firmware and install rockbox?

Cos I haven't got any Apple software :-)


http://www.rockbox.org

Then you can drag and drop to your hearts content :-)


Maybe, but it would mean buying an ipod. Not summat I want to do.
--

blackbat /\x/\

mp3 player output volumes
 

On Sun, 31 Jan 2010 13:51:57 +0000, Adrian C
wrote:

On 30/01/2010 19:10, blackbat wrote:
On Sat, 30 Jan 2010 18:52:57 -0000, "Woody"
wrote:

Why hate iTunes? You don't have to use it tobuy anything but
it really is quite good at managing the contents of an iPod.

I know some people like it.

I guess I can't see what could be easier than dragging and dropping in
Windows. Simply using my mp3 player in the style of a memory stick.

I've got a thing about bloating my PC with unnecessary proprietary
software.

The iPod is also bloated then, doubt you actually will use playlists,
genius or their genre library management features.

Why not remove the Apple firmware and install rockbox?

http://www.rockbox.org

Then you can drag and drop to your hearts content :-)

I have an unused (for the very reasons already rehearsed) ipod, and
when I read your post, I thought I could possibly actually use it. No
such luck - rockbox doesn't support it.

Oh well, back in the drawer.

d

mp3 player output volumes
 

On 31/01/2010 18:30, blackbat wrote:

Cos I haven't got any Apple software :-)


http://www.rockbox.org

Then you can drag and drop to your hearts content :-)


Maybe, but it would mean buying an ipod. Not summat I want to do.

Yup. I realised that soon after I posted. Was tring to keep silent my
"Doh" moment after that slip.

Anyway, the transformer voltage stepup Jim was proposing might be worth
pursuing. A couple of LT700's from Maplin?

--
Adrian C

mp3 player output volumes
 

On 31/01/2010 18:39, Don Pearce wrote:

I have an unused (for the very reasons already rehearsed) ipod, and
when I read your post, I thought I could possibly actually use it. No
such luck - rockbox doesn't support it.

Oh well, back in the drawer.


If it's that old, it may support Winamp's builtin 'disk mode' access?

Nationwide, there is a "drawer" in every household where gadgets bought
as either presents or snap buys, go to rest. Go on, free these things!
It's cruel! They want to see daylight!

--
Adrian C

mp3 player output volumes
 

Adrian C wrote:
On 31/01/2010 18:39, Don Pearce wrote:

I have an unused (for the very reasons already rehearsed) ipod, and
when I read your post, I thought I could possibly actually use it. No
such luck - rockbox doesn't support it.

Oh well, back in the drawer.


If it's that old, it may support Winamp's builtin 'disk mode' access?

Nationwide, there is a "drawer" in every household where gadgets bought
as either presents or snap buys, go to rest.

There sure is such a draw, the problem is that most of the things in it are
extremely deficient in the memory department. :)

Go on, free these things!
It's cruel! They want to see daylight!

They will eventually, just before they are melted down somewhere in India.


--
Bill Coombes

mp3 player output volumes
 

On Sun, 31 Jan 2010 13:51:57 +0000, Adrian C
wrote:


Why not remove the Apple firmware and install rockbox?

http://www.rockbox.org

Then you can drag and drop to your hearts content :-)

Just looked at the link. Shoulda looked before my last post :-)
--

blackbat /\x/\

mp3 player output volumes
 

On Sun, 31 Jan 2010 19:10:54 +0000, Adrian C
wrote:


Anyway, the transformer voltage stepup Jim was proposing might be worth
pursuing. A couple of LT700's from Maplin?

Well maybe.
What about power? I need to power any device in a car and in the home.
Might get a bit messy.
Easier to just buy a second speaker and daisy chain it...
http://tinyurl.com/yd2m5x6

My FM transmitter is just about OK in my car but would have been nice
to boost it a little to improve Sig/Noise ratio.
--

blackbat /\x/\

mp3 player output volumes
 

On Sun, 31 Jan 2010 09:14:45 +0000 (GMT), Jim Lesurf
wrote:

ahem Too late to worry about that if you are already using Windows. 8-]

I can drag and drop just as easily in Ubuntu too ;-)

More seriously, if you can't find an mp3 player that outputs a high enough
level then you could experiment as follows. (Assuming you are happy to
solder leads, etc.)
Never happier.
Actually that's a slight exaggeration.

Buy a couple of the small signal transformers sold by CPC or similar. Try
using those to step up the output from the player. I have no idea if that
will work, but may be worth a punt if all else fails.

Possibly - thanks for the idea.
--

blackbat /\x/\

mp3 player output volumes
 

In article , blackbat
wrote:
On Sun, 31 Jan 2010 19:10:54 +0000, Adrian C wrote:


Anyway, the transformer voltage stepup Jim was proposing might be worth
pursuing. A couple of LT700's from Maplin?

Well maybe. What about power? I need to power any device in a car and
in the home. Might get a bit messy.

I'd assumed the mp3 player would be battery powered as an item meant for
portable use. The transformers obviously don't need powering. So I'm not
clear what you are asking about.

Easier to just buy a second speaker
and daisy chain it... http://tinyurl.com/yd2m5x6

My FM transmitter is just about OK in my car but would have been nice to
boost it a little to improve Sig/Noise ratio.

The transformers in my CPC catalogue list step up ratios of 1:4 and 1:10.
If the impedances are suitable, etc, that could mean up to a 12dB or 20dB
improvement.

LS01463 and LS01464

I've never tried them for a task like you one want, so can't say if how
well they'd work. But they are quite small and cheap, so if it were me I'd
give them a try.

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

mp3 player output volumes
 

In article , blackbat
wrote:
On Sun, 31 Jan 2010 09:14:45 +0000 (GMT), Jim Lesurf
wrote:

ahem Too late to worry about that if you are already using Windows.
8-]

I can drag and drop just as easily in Ubuntu too ;-)

That makes sense. :-) Although I tend to use ROX on top of Ubuntu/Xubuntu
as I find that makes D&D even more convenient.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

mp3 player output volumes
 

blackbat wrote:
On Sat, 30 Jan 2010 18:52:57 -0000, "Woody"
wrote:

Why hate iTunes? You don't have to use it tobuy anything but
it really is quite good at managing the contents of an iPod.

I know some people like it.

I guess I can't see what could be easier than dragging and dropping in
Windows. Simply using my mp3 player in the style of a memory stick.


It's useful for things like podcasts, audio books etc. where it will
keep track of your downloads and, if required, delete from your ipod
podcasts you've listened to.

--
David Kennedy

http://www.anindianinexile.com

mp3 player output volumes
 

Jim Lesurf wrote:
In article , blackbat
wrote:
On Sun, 31 Jan 2010 19:10:54 +0000, Adrian C wrote:

Anyway, the transformer voltage stepup Jim was proposing might be worth
pursuing. A couple of LT700's from Maplin?

Well maybe. What about power? I need to power any device in a car and
in the home. Might get a bit messy.

I'd assumed the mp3 player would be battery powered as an item meant for
portable use. The transformers obviously don't need powering. So I'm not
clear what you are asking about.

Easier to just buy a second speaker
and daisy chain it... http://tinyurl.com/yd2m5x6

My FM transmitter is just about OK in my car but would have been nice to
boost it a little to improve Sig/Noise ratio.

The transformers in my CPC catalogue list step up ratios of 1:4 and 1:10.
If the impedances are suitable, etc, that could mean up to a 12dB or 20dB
improvement.

LS01463 and LS01464

I've never tried them for a task like you one want, so can't say if how
well they'd work. But they are quite small and cheap, so if it were me I'd
give them a try.

How about a dual op-amp and 4 resistors?

--
Eiron.

mp3 player output volumes
 

In article , Eiron wrote:
Jim Lesurf wrote:
In article , blackbat
wrote:
On Sun, 31 Jan 2010 19:10:54 +0000, Adrian C
wrote:

Anyway, the transformer voltage stepup Jim was proposing might be
worth pursuing. A couple of LT700's from Maplin?

Well maybe. What about power? I need to power any device in a car and
in the home. Might get a bit messy.

I'd assumed the mp3 player would be battery powered as an item meant
for portable use. The transformers obviously don't need powering. So
I'm not clear what you are asking about.
[snip]

How about a dual op-amp and 4 resistors?

One of the reasons I suggested transformers is that - unlike op amps - they
don't require powering. But, yes, if power is available then a couple of op
amps, etc, should work.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

mp3 player output volumes
 

On Mon, 01 Feb 2010 09:04:24 +0000 (GMT), Jim Lesurf
wrote:

Although I tend to use ROX on top of Ubuntu/Xubuntu


You're just showing off now...
--

blackbat /\x/\

mp3 player output volumes
 

On Mon, 01 Feb 2010 09:02:00 +0000 (GMT), Jim Lesurf
wrote:


I'd assumed the mp3 player would be battery powered as an item meant for
portable use. The transformers obviously don't need powering.


Hmm, didn't realise that. In my ignorance I thought they would.
--

blackbat /\x/\

mp3 player output volumes
 

On Mon, 01 Feb 2010 09:02:00 +0000 (GMT), Jim Lesurf
wrote:

The transformers in my CPC catalogue list step up ratios of 1:4 and 1:10.
If the impedances are suitable, etc, that could mean up to a 12dB or 20dB
improvement.

LS01463 and LS01464


OK - really not my field (as you probably guessed!) but I thought to
increase the volume you would need to add some sort of power.

I can understand a transformer stepping down a voltage but can't see
how it can step up without losing or altering something else i.e.
possibly decreasing the current. Not sure how that would result in an
increase in volume.

Was it Newton that said 'Yer get owt for nowt' ?

Haven't got a clue what I'm talking about though!

Are you saying that simply passing the o/p from my mp3 headphone
socket through one of your transformers will boost the volume out to
the speaker?



--

blackbat /\x/\

mp3 player output volumes
 

In article , blackbat
wrote:
On Mon, 01 Feb 2010 09:04:24 +0000 (GMT), Jim Lesurf
wrote:

Although I tend to use ROX on top of Ubuntu/Xubuntu


You're just showing off now...

Not really. ROX makes life easier from my POV as it gives me the same sort
of filer/GUI as I'm accustomed to with RISC OS. And is a doddle to install
via synaptic or 'zero install'.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

mp3 player output volumes
 

"blackbat" wrote in message
...
On Mon, 01 Feb 2010 09:02:00 +0000 (GMT), Jim Lesurf
wrote:

The transformers in my CPC catalogue list step up ratios of 1:4 and 1:10.
If the impedances are suitable, etc, that could mean up to a 12dB or 20dB
improvement.

LS01463 and LS01464


OK - really not my field (as you probably guessed!) but I thought to
increase the volume you would need to add some sort of power.

I can understand a transformer stepping down a voltage but can't see
how it can step up without losing or altering something else i.e.
possibly decreasing the current. Not sure how that would result in an
increase in volume.

You are absolutely right, stepping up the voltage results in a decrease in
*available* current. However the current you require to drive an amplifier
or your FM little transmitter is only a small fraction of that required to
drive headphones. So only a fraction of the available current from your mp3
player was being used anyway.

To take an example. If the mp3 player can manage 0.5V output into 32 ohm
headphones, that means it can deliver 0.5/32 = 15.6 mA. However a typical
small amplifier might have an input impedance of 10kohm, so the current
flowing at 0.5V output is only 0.5/10 = 0.05 mA. Put a transformer with a
1:4 step-up in place and the voltage is stepped up by a factor of 4 to 2V.
The input current into the amp is now 2/10 = 0.2 mA. Because of the
transformer the current required from the player is 4 times that = 0.8mA,
still well below the 15.6mA that it is capable of. Note that since the power
in an electrical signal is proportional to the square of the voltage the
power delivered to the load is increased by a factor of 4 squared = 16
times.

David.

mp3 player output volumes
 

In article , blackbat
wrote:
On Mon, 01 Feb 2010 09:02:00 +0000 (GMT), Jim Lesurf
wrote:

The transformers in my CPC catalogue list step up ratios of 1:4 and
1:10. If the impedances are suitable, etc, that could mean up to a 12dB
or 20dB improvement.

LS01463 and LS01464


OK - really not my field (as you probably guessed!) but I thought to
increase the volume you would need to add some sort of power.

Yes. But the trick is that transformers can allow you to get the 'extra
power' from the signal source. The snag is - as you'd expect - there are
limitations to this, and it only works in appropriate cases.

I can understand a transformer stepping down a voltage but can't see how
it can step up without losing or altering something else i.e. possibly
decreasing the current.

Yes, the required current also changes. See below.

Not sure how that would result in an increase in
volume.

Was it Newton that said 'Yer get owt for nowt' ?

Didn't know he was from Yorkshire. :-)

For more detailed explanations have a look at

http://www.st-andrews.ac.uk/~www_pa/...rt5/page2.html

or

http://www.st-andrews.ac.uk/~www_pa/...rt6/page4.html

However the basic idea is a fairly simple one.

Power = Voltage x Current

So what the transformer requires to work is that the product of Voltage and
Current drawn in from the source must equal (or usually exceed) that taken
out by the load.

For the sake of example, imagine the following case.

You want to drive the input of an FM TX with signal voltage of 1 Volt
for the result to be loud enough. You have a 1:10 step-up transformer
and drive the FM TX through this.

That means you need to apply 0.1 Volts to the input of the transformer.

Assume the FM TX has an input impedance of 10,000 Ohms (10kOhms). That
means it has to be given 0.1 milliamps when 1 Volt is applied to it.
i.e. the input signal power entering the FM TX will be

1 V x 0.1 mA = 0.1 mW (milliwatts)

The source is your mp3 player. That has to provide 0.1 Volt of signal
to the transformer. But to do this it also has to deliver at least
0.1 mW into the transformer. That means it will have to supply 1 mA.


Now if we'd connected the mp3 player to the FM TX *directly* with no
transformer it would only have had to supply 0.01 mA for 100 mV as
the load it would be presented with would be 10kOhms. But with the
transformer in place the mp3 player has to supply ten times as much
current to give the required power for the transformer to be able
to present 1V to the FM TX.

Hence (assuming a perfect transformer with no losses) the power into
and out of the transformer equal and we have drawn enough power from
the *source* (mp3 player) for things to work OK.

The result is that the mp3 player now seems to experience a load that
demands 1 mA when it applies 100 mV. i.e. it looks like 100 Ohms, not
10 kOhms! In effect we have 'transformed' the load from a 10 kOhms
resistance that needs 1 Volt into one that is 100 Ohms but only needs
0.1 Volt.


Haven't got a clue what I'm talking about though!

Are you saying that simply passing the o/p from my mp3 headphone socket
through one of your transformers will boost the volume out to the
speaker?

Probably will. The snag is that the mp3 player has to be happy to supply
the increased current. i.e. be able to provide 0.1 Volts across 100 Ohms
rather than see 10 kOhms.

It will probably be OK, though, as the chances are it expects to drive
headphones. The only ways to know are to do some measurements or simply
give it a try! The above values are just plausible round numbers. But I
suspect the mp3 player can deliver enough current, etc. What I don't
know is how good the transformers are. The above assumes they are
'ideal', but in practice they may give problems.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
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Audio Misc http://www.audiomisc.co.uk/index.html

mp3 player output volumes
 

In article ,
blackbat wrote:
I can understand a transformer stepping down a voltage but can't see
how it can step up without losing or altering something else i.e.
possibly decreasing the current. Not sure how that would result in an
increase in volume.

The input to an amp will be high impedance, so a tiny current flow. A step
up transformer will work just fine.

--
*Can vegetarians eat animal crackers?

Dave Plowman London SW
To e-mail, change noise into sound.

mp3 player output volumes
 

In article , Jim Lesurf
wrote:
[snip]

Now if we'd connected the mp3 player to the FM TX *directly* with no
transformer it would only have had to supply 0.01 mA for 100 mV as the
load it would be presented with would be 10kOhms. But with the
transformer in place the mp3 player has to supply ten times as much
current to give the required power for the transformer to be able to
present 1V to the FM TX.

Oops! Sorry, the above para was probably confusing. It muddles together
some different points without distinguishing properly! Simplest to ignore
it when reading the rest of the posting. :-/

Afraid I was half asleep when I wrote it. Apologies.

Slainte,

Jim

--
Please use the address on the audiomisc page if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

mp3 player output volumes
 

On Tue, 02 Feb 2010 09:13:10 +0000 (GMT), Jim Lesurf
wrote:


Not really. ROX makes life easier from my POV as it gives me the same sort
of filer/GUI as I'm accustomed to with RISC OS. And is a doddle to install
via synaptic or 'zero install'.


Maybe I'll give it a try on a VM
--

blackbat /\x/\

mp3 player output volumes
 

On Tue, 2 Feb 2010 09:28:03 -0000, "David Looser"
wrote:

You are absolutely right,

blushes

stepping up the voltage results in a decrease in
*available* current. However the current you require to drive an amplifier
or your FM little transmitter is only a small fraction of that required to
drive headphones. So only a fraction of the available current from your mp3
player was being used anyway.

I getcha


To take an example. If the mp3 player can manage 0.5V output into 32 ohm
headphones, that means it can deliver 0.5/32 = 15.6 mA. However a typical
small amplifier might have an input impedance of 10kohm, so the current
flowing at 0.5V output is only 0.5/10 = 0.05 mA. Put a transformer with a
1:4 step-up in place and the voltage is stepped up by a factor of 4 to 2V.
The input current into the amp is now 2/10 = 0.2 mA. Because of the
transformer the current required from the player is 4 times that = 0.8mA,
still well below the 15.6mA that it is capable of. Note that since the power
in an electrical signal is proportional to the square of the voltage the
power delivered to the load is increased by a factor of 4 squared = 16
times.

Right. Makes sense.

--

blackbat /\x/\

mp3 player output volumes
 

On Tue, 02 Feb 2010 09:29:53 +0000 (GMT), Jim Lesurf
wrote:

OK - really not my field (as you probably guessed!) but I thought to
increase the volume you would need to add some sort of power.

Yes. But the trick is that transformers can allow you to get the 'extra
power' from the signal source. The snag is - as you'd expect - there are
limitations to this, and it only works in appropriate cases.

Yup I get that now.


I can understand a transformer stepping down a voltage but can't see how
it can step up without losing or altering something else i.e. possibly
decreasing the current.

Yes, the required current also changes. See below.

Not sure how that would result in an increase in
volume.

Was it Newton that said 'Yer get owt for nowt' ?

Didn't know he was from Yorkshire. :-)

Not a lot of people do.


For more detailed explanations have a look at

http://www.st-andrews.ac.uk/~www_pa/...rt5/page2.html

or

http://www.st-andrews.ac.uk/~www_pa/...rt6/page4.html

I did - thanks.


However the basic idea is a fairly simple one.

Power = Voltage x Current

So what the transformer requires to work is that the product of Voltage and
Current drawn in from the source must equal (or usually exceed) that taken
out by the load.

For the sake of example, imagine the following case.

You want to drive the input of an FM TX with signal voltage of 1 Volt
for the result to be loud enough. You have a 1:10 step-up transformer
and drive the FM TX through this.

That means you need to apply 0.1 Volts to the input of the transformer.

Assume the FM TX has an input impedance of 10,000 Ohms (10kOhms). That
means it has to be given 0.1 milliamps when 1 Volt is applied to it.
i.e. the input signal power entering the FM TX will be

1 V x 0.1 mA = 0.1 mW (milliwatts)

The source is your mp3 player. That has to provide 0.1 Volt of signal
to the transformer. But to do this it also has to deliver at least
0.1 mW into the transformer. That means it will have to supply 1 mA.


Now if we'd connected the mp3 player to the FM TX *directly* with no
transformer it would only have had to supply 0.01 mA for 100 mV as
the load it would be presented with would be 10kOhms. But with the
transformer in place the mp3 player has to supply ten times as much
current to give the required power for the transformer to be able
to present 1V to the FM TX.

Hence (assuming a perfect transformer with no losses) the power into
and out of the transformer equal and we have drawn enough power from
the *source* (mp3 player) for things to work OK.

The result is that the mp3 player now seems to experience a load that
demands 1 mA when it applies 100 mV. i.e. it looks like 100 Ohms, not
10 kOhms! In effect we have 'transformed' the load from a 10 kOhms
resistance that needs 1 Volt into one that is 100 Ohms but only needs
0.1 Volt.


Haven't got a clue what I'm talking about though!

Are you saying that simply passing the o/p from my mp3 headphone socket
through one of your transformers will boost the volume out to the
speaker?

Probably will. The snag is that the mp3 player has to be happy to supply
the increased current. i.e. be able to provide 0.1 Volts across 100 Ohms
rather than see 10 kOhms.

It will probably be OK, though, as the chances are it expects to drive
headphones. The only ways to know are to do some measurements or simply
give it a try! The above values are just plausible round numbers. But I
suspect the mp3 player can deliver enough current, etc. What I don't
know is how good the transformers are. The above assumes they are
'ideal', but in practice they may give problems.

I think I may have found a loud enough non-ipod player now.
But I'm gonna give the transformer idea a try just for the hell of it.
Thanks for such an in-depth answer.


Slainte,

Right back at ya.

Jim

--

blackbat /\x/\

mp3 player output volumes
 

On Tue, 02 Feb 2010 15:38:56 +0000 (GMT), Jim Lesurf
wrote:


Oops! Sorry, the above para was probably confusing. It muddles together
some different points without distinguishing properly! Simplest to ignore
it when reading the rest of the posting. :-/

Afraid I was half asleep when I wrote it. Apologies.

None needed. Thanks again
--

blackbat /\x/\