DIY iPod DAC modding

posted Dec 24th 2007 10:53pm by Will O'Brien
filed under: ipod hacks

Red Wine audio offers the iMod – a service that modifies the DAC in 4th, 5th and 5.5th generation iPods. Despite requiring some fine work, the mod isn’t that difficult. [joneeboi] sent in his DIY DAC mod how-to, and even better, it’s suitable for 3rd gen and 1st gen Nanos. The audio signal is tapped directly after the DAC, and the SMD capacitors in the iPod are replaced with high end Black Gate capacitors. This is just the mod feed the best possible signal to your headphone amp

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First comment FTW!

Also, Christmas.

Posted at 12:35 am on Dec 25th, 2007 by epicelite

pretty neat idea, kudos for it!

i sure hope you are listening to just AIFFs or WAVs or something… because tapping the DAC like this might not mean anything with less quality. the headphone amp and the caps will make a difference, of course, but the resolution of compressed audio might render any DAC improvements irrelevant to the real listening experience.

Posted at 1:08 am on Dec 25th, 2007 by emilio

emilio – you could also use lossless AAC (ALAC)

Posted at 1:22 am on Dec 25th, 2007 by hogiewan

“A richer, more seductive midrange”
A seductive midrange? Hmm…

“Superior treble extension and sweetness, as well as better decay of long held notes and delicate harmonics”
Sweetness? Note decay? So it actually *modifies* the music? Hmm…

“More detail retrieval and overall transparency”
Wow, detail retrieval? You mean I can ‘retrieve’ data where no data existed before?

TOTAL AUDIOPHILE BULLSHIT? SIGN ME UP!

Posted at 5:48 am on Dec 25th, 2007 by octel

@octel – There was nothing about modifying the sound, with lower quality electronics, the passive components can lead to less than linear relationships when reproduced.

As for detail retrieval, I believe the author means that more detail is “retrieved” from the recording. If you’ve ever listened to high quality sound equipment you’ll realize that there is a LOT of detail that was not audible before.

When I use a headphone amp with my HD555’s I can hear all kinds of things I didn’t even know where there on tracks I’ve heard thousands of times.

Posted at 12:38 pm on Dec 25th, 2007 by Citizen_Insane

Be interesting to see some double-blind tests on this. I’ve noticed the placebo effect is alive and well in the audiophile community, as evidenced by things like mechanically-tuned power cords.

Posted at 2:31 pm on Dec 25th, 2007 by Orv

Well, most of the cord stuff is complete BS, but things like this mod do actually make an audible difference as does using quality components. Audiophile transformers, buffered power supplies and capacitors do make for better sounding music, but to most people it’s not worth the price to performance ratio.

Posted at 3:50 pm on Dec 25th, 2007 by Citizen_Insane

Higher quality cables tend to last longer and give a better sound by reducing noise. However stating a cable is “tuned” is a bit much. Power conditioners are very nice, expecially in areas where the current is rather irregular (*cough* lights dimming because the sub amp is drawing so many amps) or outlying areas like camps where the power lines may be old or overdrawn.

For anyone that has listened to an ipod beside a good DAC know that there is a very large room for improvement. The first time I got my nano I had to get used to the “harshness” of the signal, which gets progressively worst above the 70% mark in the volume control. Some of that is probably do to the preamp not getting enough juice and outputting “square waves” which are incredibly harsh (on the ear and speaker) due to the added harmonics.

Posted at 2:04 pm on Dec 26th, 2007 by Matt

No matter how much polish you put on your turd, it’s still a turd.

Cripes, this is MP3’s guys, the audio quality sucks. Yet people are out there trying to make the amp inthe ipod better?

I have some gold plated, unidirectional, anti-resonant speaker cables Ill sell you for $599.99 a foot. Guarenteed to sound better than anything else if you let them burn in for 91 days. (burn in process is running 240 watts RMS through them with white noise, must be into speakers not resistors or it will not work.

They are warrantyied for 90 days.

Posted at 8:57 am on Dec 27th, 2007 by fartface

interesting
i shall try it :D

Posted at 6:00 pm on Jan 3rd, 2008 by Ben Wagner

I created a tutorial based on this mod here:

http://ayl.nuwen.net/index.php/projects/diy-imod-ipod/

Posted at 2:59 am on Jan 15th, 2008 by Aaron Lee

From all the pin-outs I have seen there doesn’t appear to be an SPDIF output on the iPod.
Apple seems very keen to stop you using the iPod as a means for you to transfer music to your mates. Putting an SPDIF output on would mean your mate could sample the audio and get a perfect copy from your iPod. I reckon if you dig lightly you will find some legal artist protection clause Apple has relating to this. Sure, you could record the iPods analogue output but that’s not a perfect copy and thus satisfies the legal bit.

Hence you need to physically (and without Apples authorisation I may add) modify the iPod to get any kind of SPDIF output (as Wadia do- read on).

regarding the DAC itself it’s (likely) to be a MP3 to dual channel analogue converter- I would think it highly unlikely that Apple would use two chips; one to convert from the raw data taken from the Hard Disk to SPDIF then another to convert SPIDF to analogue when they could get a DSP to do the whole thing.
i.e. economy of scale- as they make millions of iPods there’s probably a custom IC they had made which goes in all iPods and though cost millions to develop works out cheaper in the long run They may even use the same chip to do the audio and video. Why not- if it can do a couple of MHz for video then audio’s just slower. Best of all its cheap and as we know it sounds crap anyway!

Indeed in the future there will probably just be one large ASIC that handles everything from HD control to the LCD, backlight LED’s and cap-sense wheel. Oh and that would blow all your chances of tapping into a SPDIF signal out of the water in one shot- I know that’s what I’d do!

There is a company called Wadia, but from what I see they actually modify (I’d rather not use the word hack if you don’t mind thank you very much) the code on the iPod to output the SPDIF signal. The SPDIF is then probably routed to an unused pin on the IPod connector such as 14 or 17 providing they are connected to an IC pin that can support this. They would also need a small 1:1 isolation transformer to output the SPDIF signal to spec’ I believe but I am no expert on this.

Even the quality of this depends on how their code interprets the supposed virtual analogue signals decoded by the MP3 decoder. i.e., if the MP3 decoder says the output voltage should go 153mV-164mV-178mV then their code will simply convert these values to what it thinks the equivalent SPDIF output should be. This would however remove any non linearity’s, clipping or noise caused by the iPods analogue stages, leaving you to decode the signal on something decent outside the case of the pod.

I admit iPods are terrible, I have a 160G Pod and a 16G 3GiPhone (16G needed for my losless fettish), the pod sounds like a Tandy tape recorder that’s been left in the sink and the iPhone slightly better. Okay for jogging and use in the car but not really home listening. I have the Alpine link box thing too and was going to probe this to hunt for an SPDIF signal but I don’t think I’ll bother now.

Best thing you can do to get decent sound from your iTunes library is use the computer you have your iTunes on. Buy a cheap USB to SPDIF converter for £15 (no, it won’t make any difference how much you spend, it’s digital to digital- a 1 is 1 and a 0 is 0, you don’t get 1/2s in binary thank you- it will either work or not and that’s it) Next get a DAC- I use a Cambridge Audio Dacmagic 2 Mk2. The converter does appear to output 48KHz so there’s probably some odd aliasing going on in the conversion from 44.1KHz but it sounds pretty good all the same.

The thing about replacing your mains lead is utter crap. I agree completely with “fartface” on this.

Just do the simple ohms law and you’ll see you’d have to replace all the wiring in your house back to the fuse box (or really the power station) to make any difference.

If your IEC mains cable conductor resistance is 0.05 Ohm that’s 0.05V dropped per amp. Your HiFi won’t be draining more than at the very most three amps, thats 0.15V dropped if your HiFi pulls three amps. If the caps in your HiFi can’t smooth this out then it’s been designed by idiots. Plus the current will settle down after the initial turn on inrush.

PS: please don’t call your HiFi mains cable a kettle lead. It is NOT in any way specified to be a Kettle lead and therefore it’s dangerous to use it as one!

In comparison the wiring to your fuse box will be maybe 0.5 Ohms? That’s 0.5V dropped per amp from your wall socket to your fuse box! Still, any decently designed kit should handle that kind of transient. Then consider all the drops and interference your supply goes through to the power station via all the transformers, even remote storms, static in the air etc?

I’d have said the best thing you could do to clean up your mains was run it through a very clean UPS that removes spikes and brown outs. Or you could plug your HiFi into a ring (or spur if your in the US) that you DON’T have other high current appliances on. If you do have a problem with spikes from other devices in your home you could get a specific ring (or spur) from your fuse box to your HiFi that’s used purely for this. You could also try moving your HiFi away from such noisy appliances.

Man, glad to get that rant off my chest!

Monty

Posted at 4:16 pm on Jun 12th, 2009 by Monty

Ok, on the whole power stuff, agreed. Actually I agree with most of your post.

However, apple does not use your so-called mp3 to dual channel blah blah blah. All iPods have Arm microprocessors as the main CPU and actually run an os. all of them. it outputs a non-standard digital audio signal and then a secodary dac chip takes care of the rest. This is Primarily the reason for the lack of spdif out, the signal is there, but it does not meet the format standards in order to actually talk to any comercial dac.
Also, the so called high end solution u speak of, this dock. It cannot, by any concievable means short of an act of god, produce spdif audio that actually matches the file. The neccisary pins simply Are not there, and there is no way to reprogram an iPod to output extra data on those unused pins without replacing the os.
It is simply doing a very good job
the newer iPods all have encrypted firmware, so even if you thought you could change something: not gonna happen.

Want proof? Grab an occilloscope. Compare the “spdif” from that dock and that from a computer with the same file. No matchy matchy

Posted at 10:17 pm on Aug 11th, 2009 by JB