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FiiO " Flagship " portable amp Mont Blanc/E12 discussing thread. - Page 96

post #1426 of 3213
Quote:
Originally Posted by scolaiw View Post

 

Probably E as in \mathcal{E} for EMF or electromotive force. 

DIng Ding Ding! I was just trying to keep things simple, e.g. "voltage"

 

Ha!

post #1427 of 3213
Quote:
Originally Posted by miceblue View Post

It's an annoying notation but I've seen it in textbooks often. The first time I saw it in a supplementary reading, I was like "whaaaat? Why did they use E??" D:

 

Also, ravager is correct about all of the math, but headphones also have a sensitivity rating that affects how much power is needed to get a headphone to reach X dB SPL. More sensitive headphones (i.e. earphones) require less power to reach X dB SPL than less sensitive headphones (i.e. regular 'ol over-ear headphones), thus requiring less voltage (P = E^2 / R), and thus less "volume on the amplifier"; this is why headphones with a lower sensitivity rating require a "higher volume level on the amplifier" than a less sensitive headphone to get to the same volume level.

Yes, that is absolutely true, and something I did overlook. I remember the first time I discovered that with a decent pair of Klipsch speakers. Nearly blew out the windows in my German flat!

post #1428 of 3213
Quote:
Originally Posted by scolaiw View Post

 

Probably E as in \mathcal{E} for EMF or electromotive force. 

cool, that symbol makes more sense, E has always been reserved for Electric field, I thought ravager was going to go down to the nitty gritty part of physics lol oh well

post #1429 of 3213

My E12 is out for delivery!:)

post #1430 of 3213
Quote:
Originally Posted by Chris J View Post

 

But Julian Hirsch said all amps sound the same.........rolleyes.gif

Just to make my position clear:

I do not agree with Julian Hirsch.

I was rolling my eyes at Julian Hirsch!

 

Quote:
Originally Posted by ravager View Post

Impedance acts like resistance in the analogue realm.

 

Therefore, using Ohms Law, we can generally say that Since E=I*R (E = voltage, I = current, and R = resistance), with E being constant, a higher resistance (or in our example, impedance) means less current drawn. Now POWER equation is P = I*E. So with that less current, means less power, for the same potential (voltage). The volume knob varies the voltage, just like Chris said, so in all cases, there will be more power to the headphones when the knob is turned towards max. (It is a little more complicated than this with the alternating current, but for illustration purposes, this will suffice).

 

So, using canned specs, and comparing 32 ohm to 300 ohm cans, we get something similar to this:

 

MyAmp puts out 0-11 Volts.

 

At 5 volts, we can plug in our 32 ohm cans to compute current and wattage (or by substitution, P=E^2/R)

 

But lets keep things simple. Calculate current, which is I = E/R = 5/32 = .156 amps or 156 milliamps (mA)

Then the power ( in watts) would be P = I*E = .156 * 5 = .78 watts or 780 milliwatts (mW)

 

Now do the same thing for the 300 ohm cans. I=E/R = 5/300 = .017 amps or 17 mA

 

Just by knowing what that equation is, we can see that will give much less power to the headphones

 

P = I * E = .017 * 5 = .085 watts or 85 mW. Even at 11 volts the power is P = E^2/R = 11*11/300 = 121/300 = 403 mW

 

In fact, you would need 15.3 volts to get the same "wattage" delivered to the 300 ohm headphones as compared to the 32 ohm at 5 volts.

 

Now take this information, and apply it what Chris said earlier about: "A low impedance Beyer DT990 needs just as much power as a high impedance Beyer DT990."

 

And you can see why the volume level will be lower, given the same output voltage on the high impedance cans.

 

There has to be a balance though, because if the impedance is too low, there is too much current drawn from the output and bad things can happen, with the least impactful being a blown fuse on the amp.

 

hope this helps.

 

(Geek hat off now)

Well put!

 

Just wanted to add that the first sentence "Impedance acts like resistance in the analogue realm" is incorrect and rather confusing.

Digital signals AND Analog Signals must both deal with load impedance, source impedance, line impedance.

It would be more accurate to say that impedance does not come into play in steady state DC circuits.

 

Electronics can be confusing, which explains why I never leave the house without my tinfoil hat on! tongue.gif

post #1431 of 3213
Quote:
Originally Posted by Chris J View Post

Just to make my position clear:
I do not agree with Julian Hirsch.
I was rolling my eyes at Julian Hirsch!

Well put!

Just wanted to add that the first sentence "Impedance acts like resistance in the analogue realm" is incorrect and rather confusing.
Digital signals AND Analog Signals must both deal with load impedance, source impedance, line impedance.
It would be more accurate to say that impedance does not come into play in steady state DC circuits.

Electronics can be confusing, which explains why I never leave the house without my tinfoil hat on! tongue.gif

It isn't incorrect, as I stated it. And notice the bail-out word "generally" being used. Without getting into RMS, DC loads, and the what not. At any rate, you didn't answer the question, and that was why I jumped in. Just trying to be helpful Chris J!
post #1432 of 3213

Would anyone know a specific date of release? Or at least early/mid/late march?

post #1433 of 3213
Quote:
Originally Posted by ToInfinity View Post

Would anyone know a specific date of release? Or at least early/mid/late march?


It's already out in the US. -> Miccastore.com

post #1434 of 3213

How reputable is Micca Store? I've never heard of them. 

post #1435 of 3213
Quote:
Originally Posted by ToInfinity View Post

How reputable is Micca Store? I've never heard of them. 

I received mine today, listening to it right now:)

post #1436 of 3213
Quote:
Originally Posted by ToInfinity View Post

How reputable is Micca Store? I've never heard of them. 

very, they are the first Fiio official retailer. However I never bought anything from them. 

post #1437 of 3213

I've done business with Micca.  Flawless transaction.  I recommend them.

post #1438 of 3213
Quote:
Originally Posted by cizx View Post

I've done business with Micca.  Flawless transaction.  I recommend them.
+1 Micca will get you the Fiio amp very quickly. When I bought the E11 they bundled a spare battery and charger for close to the same price.
post #1439 of 3213
Quote:
Originally Posted by ravager View Post

It isn't incorrect, as I stated it. And notice the bail-out word "generally" being used. Without getting into RMS, DC loads, and the what not. At any rate, you didn't answer the question, and that was why I jumped in. Just trying to be helpful Chris J!

Next week we'll discuss real power vs. apparent power WRT to reactive power, explain power factor and finsih off with a technical dialogue regarding reactive phase angles and back EMF.

On second thought, let's not bother.tongue.gif

Can anyone suggest a good material for a light metallic hat to block the alien radio waves manipulating my thought patterns? redface.gif
post #1440 of 3213
Quote:
Originally Posted by Chris J View Post


Next week we'll discuss real power vs. apparent power WRT to reactive power, explain power factor and finsih off with a technical dialogue regarding reactive phase angles and back EMF.

On second thought, let's not bother.tongue.gif

Can anyone suggest a good material for a light metallic hat to block the alien radio waves manipulating my thought patterns? redface.gif

i dono about any material but Celion Dion on a loop should encrypt all that goes in your head instantly :P

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