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IMOD by Redwineaudio - Page 2

post #16 of 82
This might sound a puny Hank odd coming from your lonesome, but I appreciate skilover's lucidity.

In the first place, he sums the sitch in useful language. One example:

Quote:
Originally Posted by skilover View Post
Vinnie's very straightforward proposition is that the Ipod's built-in DAC actually is excellent, it is all the follow-on circuitry designed to power headsets, control volume and offer a wide variety of equalization settings that is of poor quality. . . . Vinnie basically connects the ouput of the DAC directly to the headphone jack, putting a high-end capacitor in the path and nothing else.
Correct the run-on sentence, noun/verb disagreement and unfocused phrases and the result is Wikipedia-ready (there ought to be a Wikipedia entry on the iMod):

Vinnie's straightforward thesis is this: While the iPod 4G's (Wolfson Microelectronics WM8975) DAC is excellent, its post-DAC circuitry is mediocre at best. The quality of the headphone amp and volume control might even be characterized as poor. His solution to the problem: To connect the output of the DAC to the headphone jack directly, with only a high-quality Black Gate capacitor between the two.

Another of skilover's virtues: Though he's praising a familiar modification to an ubiquitous device, he manages to notice issues that everyone else tends to miss. Here's an illustrative morsel:

Quote:
Originally Posted by skilover View Post
Vinnie describes the IMOD sound as "analog" in nature. . . . It has soul, a certain rightness that, for example, a mid-range CD player lacks. Due to its limited power supply, the Ipod will not have the forceful bass and slam that a very well designed CD player might, but it has a sweetness, a naturalness, a warmth and a certain "rightness" of sound that are just stunning.
Note that skilover has managed to point out a basic flaw in the iPod's sound (the power supply), one which Vinnie's mod does not address, as well as a compensatory virtue (the characteristic sound of the DAC). Moreover, he's done so in refreshingly concrete terms.

99% of Head-fi discussions of the iPod's sound are reducible to this: It is (i) excellent, (ii) awful, (iii) worse than that of my other DAP(s) or (iv) better than that of my other DAP(s). None of that is ever useful to novices or anyone else; it is mere barking and cooing. However, it is extremely useful of skilover to observe that (i) because the iPod's power supply (like that of most other battery-powered portables) is weak, its bass sound lacks the impact of a good home system, but, (ii) subjectively, the iPod's DAC has a certain detail and warmth that old-school audiophile reviewers of mid-level systems tend to praise.

Comparisons between the iPod and other DAPs might be more useful if the DACs used by each were listed by the reviewer, and if reviews included comparisons with a minimum of amp/DSP interference in an attempt to discern the DACs' sound characteristics. Skilover's post suggested that idea to me. No one else's had.

Also: Skilover's mention of the bass-timid power supply suggests the possibility of another sort of mod (or, possibly, third-party solution) that might improve the sound of the iPod, one which no one seems to have attempted. No doubt there are reasons for Vinnie not to have pursued this (perhaps the mod would be impossible due to the case's dinkitude and other considerations), but the idea is worthy of discussion at the very least.

Far from being a mere commercial, skilover's post reads as if he's thought about the problems inherent in the iPod's presentation and asked Vinnie specific questions about the Red Wine Audio recipe for improved results. As a person who has written technical manuals in the past, I can appreciate skilover's efforts.

Welcome to Head-fi, Large S. Please continue to post your lucid and thoughtful observations.
post #17 of 82
Quote:
Originally Posted by scrypt View Post
Note that skilover has managed to point out a basic flaw in the iPod's sound (the power supply), one which Vinnie's mod does not address.
Hi Guys,

I never addressed the power supply because I don't believe there is any flaw to it at all. The iPod runs on a Li-Ion battery. That battery has more than enough output current to power the DAC (and the opamp section in the stock unit...which I remove in the iMod). The DAC only draws a few milli-amps (mA) of current, and it will never need more than that. It is never starved for current with the stock Li-Ion battery. You can connect any external power supply to the unit (one that has more output current than the battery), but the dac will never draw more power because it never needs it. The battery will always have more than enough to fully power the output stage! The line out is driving high impedance (e.g. the input stage of a headphone amp). It is not driving home audio speakers Even when the iPod battery indicator shows that it is almost empty, there is still plenty of current available to power the dac. The dac is fed from an internal voltage regulator. No matter if the battery is full charged or close to empty, the same voltage/current is being sent to the dac. When you connect an external power supply, again, the same voltage/current is being sent to the dac.


Hi skilover,

Thanks for your follow-up post, and I forgot to say "welcome aboard!"


Best regards,

Vinnie
post #18 of 82
HI,

Knowing the love of Vinnie's imod here I don't think there was any animosity in saying the post seemed like an advert. If this was for a different product you can bet your boots the comments might have been less charitable.

Anyhow welcome to head-fi get ready to spend lots more.


Steve
post #19 of 82
Quote:
Originally Posted by scrypt View Post
This might sound a puny Hank odd coming from your lonesome, but I appreciate skilover's lucidity.

Another of skilover's virtues: Though he's praising a familiar modification to an ubiquitous device, he manages to notice issues that everyone else tends to miss.

Note that skilover has managed to point out a basic flaw in the iPod's sound (the power supply), one which Vinnie's mod does not address, as well as a compensatory virtue (the characteristic sound of the DAC). Moreover, he's done so in refreshingly concrete terms.

It is extremely useful of skilover to observe that (i) because the iPod's power supply (like that of most other battery-powered portables) is weak, its bass sound lacks the impact of a good home system, but, (ii) subjectively, the iPod's DAC has a certain detail and warmth that old-school audiophile reviewers of mid-level systems tend to praise.

Comparisons between the iPod and other DAPs might be more useful if the DACs used by each were listed by the reviewer, and if reviews included comparisons with a minimum of amp/DSP interference in an attempt to discern the DACs' sound characteristics. Skilover's post suggested that idea to me. No one else's had.

Also: Skilover's mention of the bass-timid power supply suggests the possibility of another sort of mod (or, possibly, third-party solution) that might improve the sound of the iPod, one which no one seems to have attempted. No doubt there are reasons for Vinnie not to have pursued this (perhaps the mod would be impossible due to the case's dinkitude and other considerations), but the idea is worthy of discussion at the very least.

Far from being a mere commercial, skilover's post reads as if he's thought about the problems inherent in the iPod's presentation and asked Vinnie specific questions about the Red Wine Audio recipe for improved results. As a person who has written technical manuals in the past, I can appreciate skilover's efforts.

Welcome to Head-fi, Large S. Please continue to post your lucid and thoughtful observations.
Thank you, Scrypt, for saying so much better than I did what was enlightening about Skilover' review (I plucked the nuggets from your post). In fact, for a new poster, I think Silkover did a better job than many with > 1000 posts!!! Between the two of you, I think there is in your two posts enough information for anyone to make in informed decision....coupled with what is on Vinnie's website.

Hope to hear from you again, Skilover!

And, thanks, Vinnie, for stepping up and telling is like it was. Nothing like truth in advertising.

By the way, this is not a paid advertisement for Scrypt and Skilover!
post #20 of 82
Quote:
Originally Posted by skilover View Post
Jeeze, mates, being a bit harsh on a newbie, are you not? It's kinda sad when the very guy I'm trying to help out a wee dram has to ride in and rescue me!

So, to be perfectly straight, that was NOT a paid advert!
well it's good to know , really ! - anyway I'll repeat it , it sounds definitely like adv. .. note that I wrote "it sounds like"

deadline :
you should try a career as adv.er


& welcome here
sorry bout your wallet
post #21 of 82
Thread Starter 
Scrypt--thank you for the kind words, I could use Blanche's famous quote from Streetcar, but won't.

While your comments related to sentence structure and grammar were on point, I don't recall ever having these observations made on a board--normally on boards we are pleased with simple things like correct word usage. Do you write for a living?

I agree there is no point to saying it is "good", "bad" or "evil". One must say why.

Vinnie: I guess this is where I am confused, as perhaps are a lot of others. I know you are Mr. Battery when it comes to powering audio devices, and I understand the reason is noise floor, but so much effort and cost is invested in huge power supplies for home audio devices, including for example CD players which pretty much do the same job as an IPOD. And, you definitely can hear the difference in a unit with a humongo power supply in how effortlessly it renders bass, how sharp the transients are, and so forth. And yet you are saying that the little IPOD battery is providing enough juice quickly enough to meet all the needs of the DAC. When I listen to the IPOD, it seems to me while the sound character is lovely, and the bass actuallly is very deep, it does lack that leading edge, the sharp transients, and the amount of bass you would hear on a good home CD player. I have assumed, which we all know what the parts of that word add to, that this is due to the lack of a huge supply of unlimited voltage (or whatever a power supply puts out).

Looking forward to learning.

Kindly,

S
post #22 of 82
Quote:
Originally Posted by Vinnie R. View Post
Hi skilover and everbody,

Yes, of course this was an ad and I payed skilover a lot of money for it! Corruption isn't cheap!

I just want to apoloigize if anyone was bothered by his post because I am the one responsible for asking if he wouldn't mind posting his impressions using the iPod in his 2-channel rig.

no bother for me , at all
post #23 of 82
I just wish Vinnie would take a stab at modding the newer generation players. The idea of buying an older gen iPod just puts me off unfortunately. I know space is an issue in the new ones but couldn't the BlackGate cap just reside outside the chassis, in line with a mini cable...
post #24 of 82

Bass fall-off with iMod

If, (for some pervert reason), I connect low-impedance phones to line-out of an iMod iPod , will there be bass fall-off?
post #25 of 82
Quote:
Originally Posted by bansal98 View Post
If I connect low-impedance phones to line-out of an iMod iPod (for some pervert reason), will there be bass fall-off?
ahhah another nice thread isn't it

a lil IC cable should be the only thing one connect into the imod lineout ..
post #26 of 82
Thread Starter 
NiToNi: I asked Vinnie about that once. He ignored the request. I do think it might be a bit clumsy, but I would guess you could build it into an interconnect cable if you had one custom made. It's a thought--Vinnie? I have no idea what would happen if you inadvertently plugged a cable without the cap into the Imod and plugged it into an amp--if it would just sound bad, or if something could get broken. Also, would the capacitor somehow discharge if it didn't remain plugged into the circuit--again, I don't know. Also, if you move your Ipod from say a car stereo to a home or portable stereo, you'd have to move the cable, and the other end may require different sorts of connection plugs. Otherwise, you could make a little "pod" (ie. an "ImodPod") that could be plugged into the Imod, then you'd plug your interconnect cable into the "pod". Again a bit clumsy, but sooner or later, Vinnie will probably need to figure this one out. Evidently Apple has a large supply of Ipod Photos so we aren't going to run out soon. But, as the new ones have bigger and bigger drives, we will want him to mod a new one more and more, so, Vinnie, please keep working on this.
Kindly,
S
post #27 of 82
Quote:
if you listen to a standard Ipod with EQ turned off you realize just how poorly it sounds,
or perhaps its your music that sounds poor. Ive never turned the EQ on w/VBR mp3's and its always sound as it does coming through my HQ audio equipment in .flac format. That and your probably using garbage IEM's (IE, the ones that came with the ipod).

what a blatant advertisement. how much did he pay you to write this? $20?
post #28 of 82
Thread Starter 
Bewildered, it's all to one's personal taste. I use Kimber interconnects, not the OEM ones. And my music is just fine, really.

Kindly,
S
PS: My price to be bribed is much more than $20.00. This is really a pretty simple discussion. Apple happen to use a very good DAC, but the circuits they use to amp it, do volume and EQ, as well as the circuit board traces that follow the DAC are mediocre, but perfectly well suited to the ear buds shipped with an IPOD. All Vinnie does is remove that stuff and put a very high quality capacitor in the path to the headphone jack. The rest is done by your own external amplifier/pre-amp. The fact that this improves the signal quality should be self evident, you don't need to bribe someone to say that.
post #29 of 82
Quote:
Originally Posted by skilover View Post
Vinnie: I guess this is where I am confused, as perhaps are a lot of others. I know you are Mr. Battery when it comes to powering audio devices, and I understand the reason is noise floor, but so much effort and cost is invested in huge power supplies for home audio devices, including for example CD players which pretty much do the same job as an IPOD. And, you definitely can hear the difference in a unit with a humongo power supply in how effortlessly it renders bass, how sharp the transients are, and so forth. And yet you are saying that the little IPOD battery is providing enough juice quickly enough to meet all the needs of the DAC. When I listen to the IPOD, it seems to me while the sound character is lovely, and the bass actuallly is very deep, it does lack that leading edge, the sharp transients, and the amount of bass you would hear on a good home CD player. I have assumed, which we all know what the parts of that word add to, that this is due to the lack of a huge supply of unlimited voltage (or whatever a power supply puts out).
Hi Skilover,

Keep in mind that the output voltage of the iMod is 1Vrms. Most home CD players output 2Vrms (some even a little higher). So if you connect your iMod to your preamp and a CD player, and switch between the two, the iMod is going to give you a lower volume. You will need to turn up the volume to get it to the same level as the CD player.

The lower output voltage *might* be why you mention there is a somewhat larger amount of bass with the home CD player. It is hard to level match the two components (i.e. finding the settings on the preamps volume control so the sound level coming out of the speakers is the same), but if you could, you might be very surprised.

When it comes to home CD players, they also have an internal dac and an output stage. Their dac and output stage will also only draw milliamps of current. Just like the iPod, the dac and opamps are fed from a voltage regulators. These components don't draw nearly as much as the processing chips, display, motor, etc.

Also, home audio CD players runs on the AC line. You'll find larger power supplies in there because of the AC to DC conversion process that needs to take place inside (transformers, diodes, storage capacitors, etc). The iPod uses VERY energy efficient components, specially designed for the portable market. They consume far less power than a home audio CD player. As a result, a small, ~700mAh Li-Ion battery does the trick and it is nice and clean.
Even with the most dynamic music, the iPods dac will never call for more mA's of current that that battery cannot provide. When designing a power supply for audio, you want to make sure that it will always provided the power required for the application. The second thing is you want it to be as clean as possible. Lastly, it would be nice for it to be efficient (e.g. a linear power supply is much less efficient than a switch-mode power supply, but there are trade-offs).

Another point regarding the bass output... Just out of curiosity, have you tried ripping the same CD using WAV vs. using higher bit rate MP3, and then comparing them. If yes, did the WAV recording change (improve) the leading edge and sharp transients in any way vs the MP3?

This is good discussion!

Vinnie
post #30 of 82

Bass fall-off with iMod

Hi Vinnie:
If, (for some pervert reason), I connect low-impedance phones to line-out of an iMod iPod , will there be bass fall-off? In other words, will it maintain the square wave under 32ohms or 24ohms load?
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