[fr4c]

went to the iPod store and did a personal test using 4G iPods and using line-out through the dock. took out my portable equipment and confused some customers around me

. as i was saying, i a/b tested using line-out out of dock and headphone out with max volume.

line-out: the tone of the music was very clear and bass was tight; no fluff. everything that was supposed to be there was clearly present. music was rich and full.

headphone at max volume: everything sounds pretty much the same as line-out, but something seems missing. leaves you wanting more; sounds anemic/lacking musical qualities. bass wasnt as authoritive and upfront like before.

conclusion: as a final thought, i think a iPod + amp definitely benefits more with the use of a line-out unit. the differences aren't really noticeable, but you can hear the difference if you listen closely.

 

[JHouser]

I was amazed with the difference between the Headphone jack and the line out. The Pocket Dock is kind of spendy but well worth it.

j-

 

[bangraman]

This is my test set-up.

- Stax Omega II headphones
- Stax SRM-007t amp with two switchable inputs
- 2 x Qunex J2P 3.5mm-2RCA cables. 1.5m, from same shop from same stock delivered on the same day from QED
- iPod 3G with iMod 'hack' to bring European iPod in line with US amp power levels


The iPod was set to very nearly full volume.
The SRM-007t allows me to switch seamlessly (i.e. without a discernible break in the sound) between the two inputs. As an additional 'control' the two inputs were swapped twice once the volume was definitely matched.


Test data was Diana Krall's Live In Paris album.

The result? No difference whatsoever in terms of relative frequency response or in relative 'cleanliness' of sound. Any changes that I could hear was due to non-optimal volume matching.

 

[Eagle_Driver]

Quote:

Originally Posted by bangraman This is my test set-up. - Stax Omega II headphones - Stax SRM-007t amp with two switchable inputs - 2 x Qunex J2P 3.5mm-2RCA cables. 1.5m, from same shop from same stock delivered on the same day from QED - iPod 3G with iMod 'hack' to bring European iPod in line with US amp power levels The iPod was set to very nearly full volume. The SRM-007t allows me to switch seamlessly (i.e. without a discernible break in the sound) between the two inputs. As an additional 'control' the two inputs were swapped twice once the volume was definitely matched. Test data was Diana Krall's Live In Paris album. The result? No difference whatsoever in terms of relative frequency response or in relative 'cleanliness' of sound. Any changes that I could hear was due to non-optimal volume matching.

You mean that both the line-out and the headphone-out sound practically equal to each other? Using high-end Stax earspeakers and amp?

 

[bangraman]

No. I mean they sound the same. I've repeated this test with the HD650+Zu, a prototype high-end amp and an audio switcher and the result is the same. I'll do it with the Supermini and an MDR-V700DJ if you like! The key is setting up the headphone output volume properly, because if you don't do this you WILL hear a difference. The SRM-007t makes it very easy to get relative volumes right as it allows effortless switching between inputs.


As I've said before, in my iPod use the main reason to be of the Line Out was that I didn't have to blow out my eardrums when I connected the E5 (or any efficient pair of phones) after unplugging the amp and forgot to reset the volume. As a caveat, the input impedance of the amp will of course affect how the sound comes out. If the amp for some reason has a very low input impedance (possibly an amp optimised to amp a Headphone Out signal) then what you'll hear may be different.

 

[Eagle_Driver]

Quote:

Originally Posted by bangraman The key is setting up the headphone output volume properly, because if you don't do this you WILL hear a difference.

No wonder why simply setting the volume at maximum may not always work best - in this case, maximum setting does introduce some distortion to the output.

In my experience, amping a portable player's headphone out does work best with the volume of the portable player set slightly lower than maximum.

 

[bangraman]

That's not a universally applicable statement. It is however applicable in the case of the iPod, and also the Creative JB3 (although I didn't do an in-depth test of this one).

 

[gerG]

B-man, cool. Now we have to wonder if the difference is the ipod version (including the dock type) the gear, or the ears. Do you have a mini around to try?

btw, for those of you setting up this test, level setting is very critical. The easy way to set it is to cross connect cables (e.g. input 1 has left from line and right from phone, input 2 is the opposite) and set level of the line output so the image centers up correctly. Click the switch and the image should not shift. This makes it easy to match the levels within the resolution of the ipod volume control. Be sure to swap the cables back before doing the listening test.


gerG

 

[JHouser]

so-B, do you think the output is just a non attenuated amped signal?

j-

 

[squirt]

has anyone used an ipod with ER4s? does the ipod produce enough mw to run the ER4s well? i also have a META42 so i could use that too.

 

[Eagle_Driver]

Quote:

Originally Posted by squirt has anyone used an ipod with ER4s? does the ipod produce enough mw to run the ER4s well? i also have a META42 so i could use that too.

The iPod - at least my 4G 20GB model and the 4G 40GB model - produces adequate power to drive the Etymotic ER-4S canalphones. However, you may find the volume control near the top of its range if you adjust it loud enough.

 

[lindrone]

One test was done on an iPod Mini, one was done on a 3G iPod. Neither of which has the exact same circuit set-up as the 4G iPod, and I don't know whether the 3G and the Mini is set up the same way internally.

Personally, I've been inclined to say that the line-out does provide something that the headphone output does not. I don't think it's simply a volume matching issue either. However I've never tested that on a 3G iPod, only the 4G.

 

[JHouser]

Quote:

Originally Posted by lindrone Personally, I've been inclined to say that the line-out does provide something that the headphone output does not.

I know I rushed to make that statement earlier...But it seems now that I set up my MINT > 4G 20gig with both my HP-2's and Ety's I can't totally stand behind it. I feel a bit silly for spending $20 on the pocket Dock as it seems now that the headphone out (just under full volume) and line out are equal.

I think the only way to let this rest is if someone runs a scope comparing the two. I think that is going to be a true "Physical" test.

j

 

[bigshot]

It's really easy to set up a balanced level comparison. I can hear a definite difference between using the unamped headphone jack and a pocket dock going into a Super Mini Moy. It really isn't a subtle difference at all. The sound is fuller in the bass and punchier with both my Sennheiser PX-100s and HD-590s.

The sound quality of the PodFreq FM transmitter which uses the dock port is much better than the iTrip for two reasons... the antenna on the PodFreq eliminates a lot of the weak signal shushhing and the dock port provides a cleaner source for the transmitter to start with. I gave away my iTrip when I got a chance to try the PodFreq. The PodFreq also has a much easier way to change stations. I could never change my iTrip while I was driving.

See ya
Steve

 

[bangraman]

OK... in the interests of completeness I'm going to re-set up this test with a META and an audio switch going into a PX100, after setting the volume level on the SRM-007t.


EDIT:
OK. New setup...

Still no difference, as I said before, the volume setting is important otherwise you will hear a difference.