Is it possible to fix the bass rolloff on iPod Mini HP out?
Jun 29, 2008 at 1:15 AM Thread Starter Post #1 of 15

synaesthetic

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Note that I do not wish to use the line-out; I'm tired of carrying all that extra bulk of an amp and a DAP.

Since I don't want to carry a headamp around anymore, this would be a crucial bit of information to help me decide whether I should spend my money on a used second generation Mini and a 32gb CF card, or whether I should look at other options.
 
Jun 29, 2008 at 2:05 AM Post #3 of 15

synaesthetic

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I was under the impression that it was due to inferior-quality output capacitors. If those capacitors could be identified, replacing them may cure the problem.
 
Jun 29, 2008 at 4:58 AM Post #4 of 15

jcx

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with sensitive iems you can add series resistance, or a resistive divider

an output transformer could be a high class option but would be heavier and bulkier than many external amps

chances are size drives the too small value of the output coupling cap and it would be hard to upgrade with higher C and quality in the same size package at any cost
 
Jun 29, 2008 at 6:29 AM Post #5 of 15

QQQ

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Output capacitors are not inferior, they're just not good pair with pow-impedance phones. Try to use at least 64ohm phones, this may solve your problem to some degree.
 
Jun 29, 2008 at 8:51 AM Post #6 of 15

rds

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JCX is right. The capacitors are just too small, and there's probably not room for larger caps. Series resistance with your phones ( ~32 ohm resistors with 32 ohm phones) will give you more bass, but will halve the max volume of the ipod.
 
Jul 3, 2008 at 12:42 AM Post #9 of 15

synaesthetic

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Quote:

Originally Posted by dumbears /img/forum/go_quote.gif
If I'm not wrong, you may change the output caps from the original value 100uF to 220uF. The value of 220uF is recommended from the Wolfson: http://www.wolfsonmicro.com/uploads/...8731_8731L.pdf


Mostly I'm just trying to find out where the output caps are. I'm pretty sure Apple frowns upon schematics of their players floating around on the internet.
 
Jul 3, 2008 at 2:29 AM Post #10 of 15

darkfury18

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Check out the diyMod thread. I don't have a mini to check it out, but those caps are typically near where the caps for the line out in the diyMod are, and are physically bigger. If you have a multimeter, do a resistance test between the HP out and the caps (both sides), the resistance should be pretty low on one of the side.

I'm not sure if you'll have room to fit a non SMD cap in there though, even with the CF mod. Try asking someone who has done the CF mod and see how much space the mod frees up.
 
Jul 3, 2008 at 2:38 AM Post #11 of 15

synaesthetic

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I've taken apart my broken first-generation Mini to have a look at the guts before I work on a pristine second-generation Mini that I intend to mod. I don't know how different the logic boards are between the two models, but the room inside should be roughly the same.

I doubt I'll be able to fit non-SMD caps in here, but if I can find SMD caps that are 220uF and fit, it should alleviate the bass roll-off with my ER-4P @ 27ohms.
 
Jul 3, 2008 at 2:56 AM Post #12 of 15

dumbears

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Quote:

Originally Posted by darkfury18 /img/forum/go_quote.gif
Check out the diyMod thread. I don't have a mini to check it out, but those caps are typically near where the caps for the line out in the diyMod are, and are physically bigger. If you have a multimeter, do a resistance test between the HP out and the caps (both sides), the resistance should be pretty low on one of the side.

I'm not sure if you'll have room to fit a non SMD cap in there though, even with the CF mod. Try asking someone who has done the CF mod and see how much space the mod frees up.



Even with CF mod, there should be any space freed up, as you're swapping a micro-drive with a CF card. They're same in size factor. The whole thing is pretty compact. Unless you're going to have the caps sticked outside the chassis, you've to go with the SMD caps. You can try Tantalum Electrolytics 220uF B Case caps; they should be the same size with those original ones.

P.S. FYI. CF I is 3.3mm while CF II is 5mm. BG NX 220uF/6.3V is 8mm(d) x 11mm (l).
 
Jul 3, 2008 at 3:23 AM Post #13 of 15

synaesthetic

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Yeah, from looking at the guts of my dead 1g Mini, there's absolutely no way a pair of Blackgate NX caps will fit.

It would be a no-brainer if I were okay with carrying around an amp; I'd just diyMod it while I had it open. But I've been doing that with my 3g Nano and portable amp, it's just too much clutter and junk to carry. I want to minimize it all.

I am probably just going to say the hell with it, give in to the evil touch interfaces, and go with a D2. But ugh I hate the idea of not being able to use the controls "blind."
 

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