The iPod Poor Bass Response

[Chronon]

Part of the problem lies in the value of the capacitor used internally in the iPod.  When combined with the impedance of the load this creates a high-pass filter.  The corner frequency of this filter (the frequency below which the response rolls off) is determined by f = 1/(2∙π∙R∙C).  A small capacitance yields a larger value for this corner frequency.  A larger impedance (R) can mitigate this effect since only the product (R∙C) is important.

So, short of swapping out the capacitor, your best bet is choosing higher impedance headphones, which is part of the theme of this thread.  Helpfully, PHK Brasil posted EQ settings that are meant to compensate for this roll-off and provide a flatter spectral response for the two cases of 16Ω and 32Ω loads.

[psycho_maniac]

yes a eq setting would work i guess but doesn't that make rockbox on the ipods (specifically the 80g) make it run   slower ? what type of headphones should we choose?

[tdtooke]

Shure e2c and e3cs are in the 32ish ohm range and work nicely for me.  The e2c's are pretty affordable too, you can get them most places for under $100.  In my personal experience the earbuds that actually come with the iPod are too hard to get properly situated so you don't lose so much bass even without the aforementioned issue.  I've found just slipping those earbuds in without making alotta effort pretty much guarantees maximum bass loss.

[psycho_maniac]

yeah some ear buds just dont fit as or maybe its just your ears? the ipod earbuds fit pretty good in my ears. ok so ive been looking up the shure e2c's and this is what i found for specs.
Find Tech Specs for Shure E2c Sound Isolating Earphones on Shure.com
   Speaker Type:       Dynamic MicroDriver
   Sensitivity (at 1kHz):       105dB SPL/mW
   Impedance (at 1kHz):       16 Ohm
   Cable Length:       E2c: 1.57m (62 inches)
E2c (in black): 1.45m (56 inches)
   Net Weight:       30g (1 oz)
   Input Connector:       3.5 mm (1/8") gold-plated stereo plug
   
is this what i want?

[scorche]

Also, keep in mind that Shure has a new line of products that are "better" than the old.  I would go into further detail, but this is getting offtopic...

[soap]

Also note that many 16ohm phones (E2C I'm looking at you) are designed with the iPod in mind (and current tastes) and have a heightened bass response built in.  All this above discussion is assuming your headphones themselves have a flat frequency response (they don't) and you desire a flat frequency response (I do).


EDIT:  Clarification made to second sentence.

[saratoga]

Shure e2c and e3cs are in the 32ish ohm range and work nicely for me.  The e2c's are pretty affordable too, you can get them most places for under $100.  In my personal experience the earbuds that actually come with the iPod are too hard to get properly situated so you don't lose so much bass even without the aforementioned issue.  I've found just slipping those earbuds in without making alotta effort pretty much guarantees maximum bass loss.

The E2Cs are 16 ohms actually, so you're still getting the low impedance issue.  However, its not that bad with the 5G and Nano, so you may never have noticed.

[TexasRockbox]

What are the headphone coupling capacitor values for the ipod 5G Video?  In many portabale equipment a value of 220uf is considered a good value for ensuring a wide range of compatibility with less variation in low-end bass response.  100uf and (yikes) 47uf is where trouble begins.  Tantalum capacitors at the 220uf level are expensive and to me do not sound as good as aluminum electrolytic at the same value.  The Tantalums tend to hide fine detail.

[tdtooke]

The E2Cs are 16 ohms actually, so you're still getting the low impedance issue.  However, its not that bad with the 5G and Nano, so you may never have noticed.

 Oops, sorry about putting out bad information, haven't used or looked at e2c specs in a while, though I can say I never noticed any problems with an iPod and them.

[TexasRockbox]

Maybe make a 32ohm and a 16ohm eq preset instead of just setting everything to "0" for flat response.

[mamboman]

don't seem to encounter this issue with my 5.5G Video ipod with UE Superfi 5Pros.

[TexasRockbox]

I went digging about this capacitor issue and stumbled into something I hadn't used in several years.  The issue with the Ipod is the low impedence/low coupling capacitance.  For portable listening I picked up the Sennheiser PX-100 some years ago as these were/are the killer budget phones (32 ohms) and the Sony EX earplug series (16 ohms) and have used them almost exclusively.

Either of those (as well as many other devices) have issues with the stock output of 5G (and other generations as best I can tell).  The UE have impedences in the low teens -- really not good and having one jump through tone control hoops to compensate.

In reading around about this issue a solution is available.  Before I starting using the Sennheisers the *killer budget* phones were the Koss PortaPro, KSC35 and others in that series that uses the "titanium" drivers.  These drivers are 60 ohms.  Perfect!  This series has been available for the last fifteen years or so with many stylistic changes.  I pulled out my old Radio Shack Optimus Pro35 (Radio Shack branded version) and, voila! Bass without the tone controls and plenty of detailed highs that are not overly etched.  I think these phones mate well with the Ipod.

These phones aren't perfect and may even be "bass heavy" -- especially if one has become accostomed to the low bass output -- but there is a decent balance of the bass and treble, in my view.  These phone ARE inexexpensive, ranging from the $19.95 Koss KSC75 (earclips) to the $39.95 enclosed ear model.  The trick is to find the Koss phones with the 60ohm "titanium" drivers.  I thnk the same driver is used in each Koss or Radio Shack phone that fits the profile.

Maybe not everyone's cup of tea but certainly a pleasant and inexpensive surprise.  If you are having bass issues with the Ipod/Rockbox it might be worth a try.

[mamboman]

I am thinking of getting a portable amp to do it with my UE SF 5 Pros through the lineout which is definitely better the last time I auditioned it with the amp. need to think hard though as the amp is definitely not cheap

[scorche]

Amps definitely do make a difference (and I have been using mine through the line out for quite a while), but I am starting to wonder how on-topic this thread is...

[TexasRockbox]

An outboard amp would have high impedence inputs so the effect on the ipod bass response would be negligible.  The on-topic issues would be, I think:

1: Configuring the Rockbox equilizer for flat response given a specific load.
2: Avoiding the Rockbox equilizer usage (and thus conserving Rockbox/ipod power) by using commercially available headphones that have high impedences.