What does LOD bypass?

I think the LOD bypasses the integrated amplifier chip.

I'm not sure at all, but from reading around - that's what I would think a LOD is supposed to do.

The digital file gets converted by the DAC to an analogue signal which is then fed to an inernal amp and then to the headphones.

In order to tap on to the DAC output to use the analogue signal before is processed by the internal amp you'll have to use a LOD.

The signal is then amplified by a better quality external amp which feeds the HPs with a better quality signal.

If you connect your external amp to the HP output you are using the internaly amped signal.

Quote:

Originally Posted by High_Q 

For:

1. 5.5 gen ipod

2. iphone 3G

3. Sony X series walkman

4. Sony S series walkman

1: If stock, a glorified headphone out. Better sound but allows you to use an amp which will yield more benefits than amping the HO. However if it's an iMod, you get a true line out port that gives you a much cleaner sound. 

2: Same as stock version. 

3-4: Don't know, don't read up on the Sony players. 

 

Quote:

Originally Posted by 1audioz 

I'm not sure at all, but from reading around - that's what I would think a LOD is supposed to do.

That's what it "does" but not with all models. Read next comment. 

 

Quote:

Originally Posted by rosgr63 

The digital file gets converted by the DAC to an analogue signal which is then fed to an inernal amp and then to the headphones.

In order to tap on to the DAC output to use the analogue signal before is processed by the internal amp you'll have to use a LOD.

The signal is then amplified by a better quality external amp which feeds the HPs with a better quality signal.

If you connect your external amp to the HP output you are using the internaly amped signal.

This is true. However it doesn't really happen like that with regular ipods. To get a true line out signal, you have to get an iMod, if you got the true line out signal, Redwine wouldn't sell as many iMods as they do now.

I like to think of it as a glorified headphone out. Sure the sound is "cleaner" and more powerful and also allows you to use a portable amp but it doesn't sound as good as a true line out. 

Yeah kinda.

In an audio chain the worst component dictates the overall quality:

The dac chip will convert your digital audio with some degradation. The output may be loud enough in terms of voltage, but the chip cannot provide current.

That's where the amp circuitry comes into play, which will provide the current drive capabilities you need for headphones (especially for low impedance, low sensitivity ones) and usually also applies some gain (further increases volume), also with some degradation.

What can be observed is that the lower the impedance of the load (the headphones), the higher the noise, distortion, crosstalk, etc. numbers will be.

With decent portable players it's not really a problem, though...

Now what happens if you connect a separate/additional amp is that the integrated amp will be quite relieved. Signal degradation reduces and converges towards the specs of the amp chip / circuitry. Why? Because the connected amp has an input impedance of tens or hundreds of kiloohms, so the integrated amp doesn't really need to do much.

Now that separate/additional amp might be able to handle the load better, but will degrade the signal further (negligible if the portable player already degraded the signal more).

Still, as I said in the beginning: every component degrades the signal and the worst component dictates quality of the end result.

What people seem to forget is that the worst component usually are the headphones, e.g. with distortion levels magnitudes higher of the dac, amp, cables combined.

PS: I'd never suggest something like the imod ... for so much money I can get a new portable player and probably even some decent headphones.

Quote:

Originally Posted by High_Q 

Quote:

Wow.  That was some very useful knowledge.  Why would you not suggest imod?  What portable player do you think is quality?  What headphones do you favor?

Yea why wouldn't you? It gives an amazing sound; it's only barrier to most people being its price and the inevitable size that it's going to be with amps. 

I see that you posted that price was  a factor, and I admit it is a very high price but if I already had some tip tier IEMs or some really good headphones, what's the problem in picking it and an amp up for a good transportable rig? 

5th gen dac chips are outdated compared to the current barrage of players.

sflo2 has a dedicated line out sports dual wolfson chip and are newer that provides a better resolution.