Ipod to stereo amplifer: getting volume

[Don Bowey]

On 12/5/07 12:50 AM, in article
Pine.LNX.4.44.0712050942020.23729-100000@uno.canit.se, "Dominic-Luc Webb"
<dlwebb@canit.se> wrote:

On Wed, 5 Dec 2007, Eeyore wrote:
---
Since the input impedance of your system is so much higher than the
impedance of the earbuds, I wouldn't think so.

Errr uhhh, I'll check the specs, but I stereo was lower:

Ipod earbud: 32 Ohm
Stereo amp: 8 Ohm (I'll check again)

No.

The "8 ohms" is certainly the output of the stereo amplifier, and
has no relevance to the topic.

It's the input impedance that matters. But it won't matter since
it will be very high, tens of thousands of ohms.

It's a red herring. The ipod's headphone output is just fine for driving an
amplifier input.

Graham


Thanks all, and I certainly stand corrected on the input impedence of
my stereo.

As for this being a red herring, I point out that the reason for my
original post was that I do not get much volume at my stereo speakers
through my stereo amplifier when I connect an Ipod via the headphone
jack. I asked if this could be an impedence mismatch or too low
power (or something else). John Fields suggests that the output
voltage may be too low, and I have now seen there are amplifiers
for Ipods that are apparently intended to boost the signal for
connecting to stereos. Seeing as the Ipod is a very small
portable device, I could guess that maybe the output to the
headphones drops off sharply as the battery runs down.

Dominic

I could guess it would just quit working if the battery runs low. I could
also guess you like to raise issue where there are none.

 

[Dominic-Luc Webb]

On Wed, 5 Dec 2007, Bob Masta wrote:

On Wed, 5 Dec 2007 13:29:50 +0100, Dominic-Luc Webb <dlwebb@canit.se
wrote:

These appear to be our axioms:

1. Volume through stereo AUX is low (compared to other inputs)
2. Volume is low when Ipod volume dial is turned all the way up
3. Impedence (Ipod 32 Ohm, stereo input thousands Ohms) is not problem
4. Battery rundown does not cause volume drop on Ipod
5. Adding a 30 Ohm resistor has improved volume for some people
6. Output voltage from headphone jack might be lower than ideal

I can easily test point 5, and I will put my trusty meter on an Ipod
headphone to investigate point 6 by comparing to me receiver input
specs.


The meter test will be a problem, unless you have a very good meter...
and even then it won't be simple. Your meter will at least have to
have a sensitive AC Volts range, and preferably true RMS.

Oscilloscope (I have one)?

I was thinking that rather than trying to get absolute values,
to compare my equipment, like CD players, etc that result in a
"normal" sound intensity through the stereo to what the Ipod does.
If the difference in volume was small, I could see this also
being problematic, but actually the low volume from the Ipod was
noticable enough to make me want to "fix the problem" . The
difference is bascially like a shout (scream???) versus a whisper.
I am hoping my oldest crappiest meter will catch such difference.

Dominic

 

[John Fields]

On Wed, 05 Dec 2007 07:27:14 -0800, Don Bowey <dbowey@comcast.net>
wrote:

On 12/5/07 12:50 AM, in article
Pine.LNX.4.44.0712050942020.23729-100000@uno.canit.se, "Dominic-Luc Webb"
dlwebb@canit.se> wrote:

On Wed, 5 Dec 2007, Eeyore wrote:
---
Since the input impedance of your system is so much higher than the
impedance of the earbuds, I wouldn't think so.

Errr uhhh, I'll check the specs, but I stereo was lower:

Ipod earbud: 32 Ohm
Stereo amp: 8 Ohm (I'll check again)

No.

The "8 ohms" is certainly the output of the stereo amplifier, and
has no relevance to the topic.

It's the input impedance that matters. But it won't matter since
it will be very high, tens of thousands of ohms.

It's a red herring. The ipod's headphone output is just fine for driving an
amplifier input.

Graham


Thanks all, and I certainly stand corrected on the input impedence of
my stereo.

As for this being a red herring, I point out that the reason for my
original post was that I do not get much volume at my stereo speakers
through my stereo amplifier when I connect an Ipod via the headphone
jack. I asked if this could be an impedence mismatch or too low
power (or something else). John Fields suggests that the output
voltage may be too low, and I have now seen there are amplifiers
for Ipods that are apparently intended to boost the signal for
connecting to stereos. Seeing as the Ipod is a very small
portable device, I could guess that maybe the output to the
headphones drops off sharply as the battery runs down.

Dominic


I could guess it would just quit working if the battery runs low. I could
also guess you like to raise issue where there are none.

---
Bingo!


--
JF

 

[Dominic-Luc Webb]

On Wed, 5 Dec 2007, Don Bowey wrote:

I could guess it would just quit working if the battery runs low. I could
also guess you like to raise issue where there are none.

I admit ignorance in asking about possible sources of this problem.
I own the stereo, which works great otherwise, but have never owned
an Ipod, and don't know much about them other than I do not get
much volume when played through my stereo receiver. This left me
asking questions. My question about the impedence mismatch was
answered, and I recognize this as a non-issue. In this sense, I am
guilty of raising issues where there are none. That still leaves
the volume problem. Am I halucinating? Maybe! But so are a lot of
other people on this side. Here is an example from unrelated people:

http://headwize.com/ubb/showpage.php?fnum=3&tid=6568

There are commercial products for this, and as I am learning,
people are buying things like headphone pre-amps, such as:

http://geekwithfamily.com/2006/06/30/audiophile/fatman-itube-by-tlaudio-ipod-dock-and-tube-amplifier/

Volume issue is quite real, but I can only speak for my stereo receiver
and one other and a couple models of Ipods that I have connected. The
reason and solution now go in direction of a preamp.

Dominic

 

[TJB]

Don't forget there is supposed to be a proper "line-out" signal available on
the ipod's dock connector, which ought work much better than the headphone
output when trying to feed the signal into your receiver. You'll need to
get a suitable adapter cable to connect this up though. I should also say I
haven't actually tried doing this, so no promises ...

 

[Dominic-Luc Webb]

On Thu, 6 Dec 2007, TJB wrote:

Don't forget there is supposed to be a proper "line-out" signal available on
the ipod's dock connector, which ought work much better than the headphone
output when trying to feed the signal into your receiver. You'll need to
get a suitable adapter cable to connect this up though. I should also say I
haven't actually tried doing this, so no promises ...

Thanks bunches TJB for this new "lead" on the case of the missing Ipod
volume. Hunting around, I found item below on Ebay. Adapter for Ipod
line out is clearly not a microphone plug, so there is no uncertainty
I was using the headphone output. Amazing people are selling these for
100 bucks in the USA.


HIGH END iPOD LINE OUT DOCK CABLE TO RCA FOR AMPLIFIER

http://cgi.ebay.com/HIGH-END-iPOD-LINE-OUT-DOCK-CABLE-TO-RCA-FOR-AMPLIFIER_W0QQitemZ190180039965QQihZ009QQcategoryZ90964QQssPageNameZWDVWQQrdZ1QQcmdZViewItem#ebayphotohosting


I never thought of an Ipod as being worthy of "high end" anything since
those I know who own Ipods are playing really crappy MP3 files. If I
find someone who has one of these adapters, I'll give this a try.

Dominic

 

[TJB]

Here in the UK ebay has this one, which looks rather more sensibly priced:

http://cgi.ebay.co.uk/Hi-Fi-CABLE-for-iPod-Dock-Port-to-Stereo-RCA-Nano-Photo_W0QQitemZ130155923382QQihZ003QQcategoryZ116850QQcmdZViewItem

BTW, if you do ge try one of these let me know if it works - as I have the
same problem!

 

[Dominic-Luc Webb]

On Thu, 6 Dec 2007, TJB wrote:

Here in the UK ebay has this one, which looks rather more sensibly priced:

http://cgi.ebay.co.uk/Hi-Fi-CABLE-for-iPod-Dock-Port-to-Stereo-RCA-Nano-Photo_W0QQitemZ130155923382QQihZ003QQcategoryZ116850QQcmdZViewItem

BTW, if you do ge try one of these let me know if it works - as I have the
same problem!

Had problems with the link, but www.ebay.co.uk and Item 130155923382
gave the obvious item. 2.95 is pretty cheap in any currency. It even
specifies this beast as producing "the very best quality sound
output from your iPod as it utilises the optimum signal from the
docking port of your player rather than the output from the earphone
socket". This statement and yours is in line with my observations.

So, maybe I am not insane after all. Yippie!

Dominic

 

[Michael Black]

Dominic-Luc Webb (dlwebb@canit.se) writes:

Volume issue is quite real, but I can only speak for my stereo receiver
and one other and a couple models of Ipods that I have connected. The
reason and solution now go in direction of a preamp.

Have you tried a different cable between the iPod and the stereo?

Michael

 

[Michael Black]

"TJB" (tim.baldwin@tinymail.NOSPAM.co.uk) writes:

Don't forget there is supposed to be a proper "line-out" signal available on
the ipod's dock connector, which ought work much better than the headphone
output when trying to feed the signal into your receiver. You'll need to
get a suitable adapter cable to connect this up though. I should also say I
haven't actually tried doing this, so no promises ...


This is misleading. "Line out" on such portable units tend to have an

output that is independent of the volume control, which can be nice, but
there's nothing really magic about it otherwise. That portable cassette
player I have that I sometimes feed into a stereo amplifier has no line out,
and the headphone jack is fine. That portable CD player that I similarly
feed into a stereo amplifier has both line out and headphone jacks, and
there's no difference in the sound (other than that the line out is
not controlled by the unit's volume control). It's subjective, but
when I checked yesterday because of this thread, the headphone jack
even seemed to be a bit louder than the line out.

Michael

 

[Dominic-Luc Webb]

On 6 Dec 2007, Michael Black wrote:

This is misleading. "Line out" on such portable units tend to have an
output that is independent of the volume control,

Argggh, now about to rip hairs out of my head..... Measurements!
That is where I will go.

Dominic

 

[John Fields]

On Thu, 6 Dec 2007 18:07:50 +0100, Dominic-Luc Webb
<dlwebb@canit.se> wrote:

On 6 Dec 2007, Michael Black wrote:

This is misleading. "Line out" on such portable units tend to have an
output that is independent of the volume control,

Argggh, now about to rip hairs out of my head..... Measurements!
That is where I will go.

--
JF

 

[John Fields]

On Thu, 6 Dec 2007 18:07:50 +0100, Dominic-Luc Webb
<dlwebb@canit.se> wrote:

On 6 Dec 2007, Michael Black wrote:

This is misleading. "Line out" on such portable units tend to have an
output that is independent of the volume control,

Argggh, now about to rip hairs out of my head..... Measurements!
That is where I will go.

---
You might save yourself a lot of grief by just building a simple pre
(post?) amp: (View in Courier)



LIN>------|-\

--
JF

 

[John Fields]

On Sun, 09 Dec 2007 08:22:58 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Thu, 6 Dec 2007 18:07:50 +0100, Dominic-Luc Webb
dlwebb@canit.se> wrote:

On 6 Dec 2007, Michael Black wrote:

This is misleading. "Line out" on such portable units tend to have an
output that is independent of the volume control,

Argggh, now about to rip hairs out of my head..... Measurements!
That is where I will go.

---
You might save yourself a lot of grief by just building a simple pre
(post?) amp: (View in Courier)



LIN>------|-\

---
oOPS...

Hit the 'send' button too soon.



--
JF

 

[Dominic-Luc Webb]

On Sat, 1 Dec 2007, Jamie wrote:

check your head phone's impedance. I think you'll find them in the
low area like 4, 8, 16,32 ohms etc//
If this is the case, you could use a simple approach which might cause
a little audio quality drop and that would be to use a matching
audio transformer which will bring the output up to line level voltages
and place a load on the IPod. You would need 2 since there is a stereo
signal involved here.

if you don't do the transformer method, you could employ a dual audio
op-amp with a loading resistor on the Ipod output. the audio amp
would then bring the signal up to line level voltages.

This is just a basic run down..

Thanks, I think I understood this. We could not find any specs on
the Ipod headphone jack or the headphones. My stereo is well
documented though.

Dominic

 

[Dominic-Luc Webb]

Thanks John for bringing me into some logical reasoning. I'll
check my stereo specs and think on the math you have offered.

Dominic

 

[Dominic-Luc Webb]

On Sun, 2 Dec 2007, John Fields wrote:

I was wondering if an impedence mismatch might explain the lack
of volume?

---
Since the input impedance of your system is so much higher than the
impedance of the earbuds, I wouldn't think so.

Errr uhhh, I'll check the specs, but I stereo was lower:

Ipod earbud: 32 Ohm
Stereo amp: 8 Ohm (I'll check again)

Dominic

 

[Michael Black]

Dominic-Luc Webb (dlwebb@canit.se) writes:

On Sun, 2 Dec 2007, John Fields wrote:

I was wondering if an impedence mismatch might explain the lack
of volume?

---
Since the input impedance of your system is so much higher than the
impedance of the earbuds, I wouldn't think so.

Errr uhhh, I'll check the specs, but I stereo was lower:

Ipod earbud: 32 Ohm
Stereo amp: 8 Ohm (I'll check again)

No.

The "8 ohms" is certainly the output of the stereo amplifier, and
has no relevance to the topic.

It's the input impedance that matters. But it won't matter since
it will be very high, tens of thousands of ohms.

Since that will not place a load on the iPod, there will be no problem.

The only caveat is if, as someone suggested, the output of the iPod
really does depend on a low impedance load to operate. And as I said,
while that would explain the problem, I've not seen any units that
actually do require a load in order to operate properly.

Michael

 

[Dominic-Luc Webb]

Hi again everyone!

I have now made some measurements regarding the output of the
Ipod headphone jack. Specifically, I compared:

Ipod model M92822V, ver 3.1.1
Philips DVP 3010 CD/DVD player of my stereo

Meter was analog voltmeter with 600 mV scale. Not ideal, but
this is what was readily available that had sensitivity and
would work for comparison purposes. I know this meter to be
able to detect 20-30 mV.

Result:

Ipod at max volume: no detectable deflection ever

CD/DVD player of stereo: signal hovered between 100 and 250 mV
and was often sustained ~200 mV

Conclusion

Similar results were obtained for other stereo system
equipment. I recognize this can come about in a couple ways,
but it is now clear the power from the Ipod is not in the
same league as regular stereo equipment. It looks like my
next step is a preamp.

Comments welcome and appreciated.

Dominic