For an audio waveform, the ultimate measurement is to listen to the result.
DACs don’t produce audio waveforms, they produce electrical waveforms which can be fed into a pair of headphones. If you want to know how good a DAC is, you need to look at the waveform it produces. You can do this with headphones, but its very difficult, and the results will depend on the choice of headphones. Choose poorly and your results may not be easy to generalize.
However, you could load the device with a resistance and measure the current available for a given signal. The limitation is yout Ic orcollector current.
Ugh, no its not. Collector current is on BJTs, but these are FETs. There is no collector. There is no Ic. Don’t tell me about it because it doesn’t exist.
What you mean to say is probably the short circuit current, although this is usually not measured for DACs because it can damage them. Instead you measure the output impedance by varying the load impedance at constant voltage and measuring the voltage drop. Once you have the output impedance, you can calculate the current for any load.
Go back to ypur post (11) and carefully re-read. The comparison is between two Austria Microsystems based devices, the v2 e200 and Clip. You have forgotten that the v1 device is a PortalPlayer based platform, very different.
Nope. Although the e200v1 does use a PP CPU, it also uses a AMS DAC. The specific chip, the PP5024 is as aPP5022 + AS 3514. The Clipv1 and Fuzev1 use an AMS 3525 CPU, which also has an onboard AS3514. So same DAC, same voltages.
Now that you know that, go back and read what I wrote:
" there is no difference in power they can theoretically supply. I doubt there is any difference, since the E200v1, E200v2, Clip and Clip Zip all use similar AMS DACs driven at the same voltage."
Note that I’m refering to power specifically. There is a difference in impedance , but not one in power. So while the two devices have different output impedance (due to the capacitive vs. direct coupling issue I explained above), they have almost identical voltages available because they have identical amplifiers and regulators.
You really have no idea of the experience of those you choose to bully.
Bullying? please, I’m just stopping you from giving ignorant advice in this thread. I’m sorry that has upset you so much, but as I’ve said before I’m not going to let you spread nonsense around just to spare your feelings. You are simply wrong here. There is no way to sugar coat that. The best I can do for you is correct your mistakes and give you the information you need to educate yourself.
With the smaller battery of the Clip, there is a trade between raw power and runtime
Actually, the Clip output level is about as high as any portable DAP made, of any battery size. What you’re saying makes intuitive sense, but if you look at the situation a little more carefully, you’ll see why its wrong. With 32 ohm headphones, a 2V swing on the amp output results in just 15.6 mW of output power per channel! And no portable player can manage even this. So the actual electrical power delivered is typically very small. Under typical conditions with ear buds, most people are just delivering a few hundred microwatts of power per ear. With such low power involved, the actual draw of the DAC+Amp is basically negligible and the real limitation becomes not the battery capacity, but rather the power supply voltages available (typically 2.5v in most SOC designs).
I’m a devices guy, quite familiar with the topologies involved.
No you are not. You don’t really understand much of anything about these devices. Let me put this politely: you need to get your head out of your butt, admit that you’re wrong, and start reading about this stuff. You obviously have some background in electronics, so there is no reason you couldn’t understand this if you took the time. There are plenty of resources available.
Start with the wiki page I linked before explaining the relation between output impedance and dampening so you understand why impedance matters. Then Google ‘nwavguy’ and read through his detailed discussions of proper headphone amplifier testing. Thats all the background you need. Then look at his testing of the Clip+'s maximum output level and output impedance. Finally, if you really want to know how these devices work, take a look at our source code for the Clip+'s DAC driver. In particular my patches for maxing out the volume level may be intereseting to you, since a lot of testing went into those and is still archieved on the ABI forums.
Second, who mentioned simulation? I tried to explain to you how the output impedance of amplifiers relates to performance, and how coupling relates to impedance, but this isn’t related to simulating anything. Its just basic amplifier terminology familiar to anyone who has worked in electronics or acoustics. I get it that you think you have some kind of understanding here, and maybe you do know something about electronics in general, but given that you keep misunderstanding what common terms mean in this context, maybe you should reconsider. Or at least take a look at that wikipedia page I gave you before.
