The above pictures have been image processed for quick readability even as a thumbnail. The test signal we see is a 1kHz sinus at 0dBFS. I've tried different (digital) dBFS levels and it appears the maximum level on the headphone out really is software limited.
Please correct me on any mishap with the calculations.
In order to do a quick test, generate a 50/60Hz or 100/120Hz sine wave signal, embedd it into iTunes as a WAV file and synchronize it to your iPod. Then connect a regular multimeter (frequency dial) with the help of an open mini plug or a special test cable. The reading should show an accurate figure of your iPod's maximum RMS output level (for sinusoidal signals) which you can then use to calculate dBu figures. You may of course also employ a true RMS meter.
Cheers,
Sebastian.
Please correct me on any mishap with the calculations.
In order to do a quick test, generate a 50/60Hz or 100/120Hz sine wave signal, embedd it into iTunes as a WAV file and synchronize it to your iPod. Then connect a regular multimeter (frequency dial) with the help of an open mini plug or a special test cable. The reading should show an accurate figure of your iPod's maximum RMS output level (for sinusoidal signals) which you can then use to calculate dBu figures. You may of course also employ a true RMS meter.
Cheers,
Sebastian.
i don't know what all this Urms, VP, LP, etc means.
an ipod has a audio amp in it. all audio amps have peak voltages they are capable of delivering to the load. it is usually measured in +/- Volts RMS.
would think it would be clearly specked out? maybe not.
can anyone here answer what the max RMS voltage output of an ipod is or do i have to drive 45min to a lab with a scope and measure myself. from the experimenting/playing i've done so far i can be certain the ipod's output is much less than line level (maybe like 250mV - 500mV).
thanks.
an ipod has a audio amp in it. all audio amps have peak voltages they are capable of delivering to the load. it is usually measured in +/- Volts RMS.
would think it would be clearly specked out? maybe not.
can anyone here answer what the max RMS voltage output of an ipod is or do i have to drive 45min to a lab with a scope and measure myself. from the experimenting/playing i've done so far i can be certain the ipod's output is much less than line level (maybe like 250mV - 500mV).
thanks.
i dont know what anything sek is saying. i don't even own a scope, let alone sophisticated computer measuring equip like he suggests using.
basically i want to make a attenuator/booster so i can convert the ipod voltage output level to line level RCA so i can connect it to a stereo. like cd, tv, vcrs, etc all put out about ~1VRMS. ipods put out something different than ~1VRMS. what does an ipod put out? from experiment in my basement i have found it to be about 1/2 - 2/3 the voltage signal output of a cd player.
does this clarify my question? its not that i dont want to take your advise, just dont have thousands of dollars to spend on computer equipment right now. can someone please just tell me "the analog output of an ipod through its 1/8 stereo female is XYZmV)
thanks.
basically i want to make a attenuator/booster so i can convert the ipod voltage output level to line level RCA so i can connect it to a stereo. like cd, tv, vcrs, etc all put out about ~1VRMS. ipods put out something different than ~1VRMS. what does an ipod put out? from experiment in my basement i have found it to be about 1/2 - 2/3 the voltage signal output of a cd player.
does this clarify my question? its not that i dont want to take your advise, just dont have thousands of dollars to spend on computer equipment right now. can someone please just tell me "the analog output of an ipod through its 1/8 stereo female is XYZmV)
thanks.
Hi gain,
you're sitting at a computer, I'll bet it is already capable of creating that 0dBfs file that Sek talks about.
I suspect you have a DMM.
You only need to do some reading and ask the right questions if the literature is beyond comprehension.
He is not asking you to spend any money. Simply to use your brain.
Go Read.
you're sitting at a computer, I'll bet it is already capable of creating that 0dBfs file that Sek talks about.
I suspect you have a DMM.
You only need to do some reading and ask the right questions if the literature is beyond comprehension.
He is not asking you to spend any money. Simply to use your brain.
Go Read.
AndrewT said:
Thanks for the heads up, Andrew.
gain said:
The symbol U is derived from lat. urgere (to urge, push, press) and is the old fashioned way of designating a Voltage. The international SI unit is V, which some researchers critizise (due to it's ambiguity). That still leaves us with L, which stands for the level.
So all you are looking for is in the above posts. You know what the character '≈' means, right?
Not with Apple.
iPods are consumer products. They rather not specify it at all than risk a comparison with the competition.
Erm, hello?
I'm trying to explicitly telling you how to do it with a regular computer and without a scope here!
By signal generator I of course mean free software for you to download. Google is your friend.
Let me repeat for you: ≈ 0.33Vrms
But please keep in mind that this may not apply to all iPods.Take a look at this Voltage and Level Converter in order to compare this to the other numbers I gave you.
No, wait. I'll do it for you!
1Vrms = 0dB(V).
0.33 Vrms ≈ -9.5dB(V).
So in order to elevate the iPod's output level to your desired input level you need a gain stage with a gain of a ≈ +3 or (in other words) a ≈ +9.5dB (without V
).Why? Because 1Vrms ≈ 3 * 0.33Vrms. And also because 0dBV - (-9.5dBV) = +9.5dB (without V).
I leave it on you to repeat the calculation for the line level I measured.
sek said:Man, you better start finding out what you actually want!
a simple circuit that takes an ipod 1/8 stereo output in on one side and outputs a signal that one gets from the output of a cd player/tape teck/etc, that can be pluggd into the line level RCA in of a standard stereo receiver.
nice extras:
- very low noise.
- operates between 12VDC-0V supply.
- adjustable gain.
simple enough? certainly someone before me has done this.
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