[JamesFiiO]

Questions about power supply for our Flagship portable headphone amps. Below is the detail of the options. What is your option?
 
A, SQ: ★★★★★, Price: ★★, Convenience: ★★★. 6 AAA li-ion batteries, provide +/- 11V power without any voltage boost and conversion. Need to put out the batteries for charging, most expensive and can’t be used during charging.
 
B, SQ: ★★★★☆, Price: ★★★, Convenience: ★★★★ build in 11V battery, provide +/- 11V power, the -11 V is converted from +11V. need special charger (+13V power adaptor)
 
C, SQ: ★★★☆, Price: ★★★★, Convenience: ★★★★★ Build in 3.7V battery, the power supply is +/-7.4V which boosted and converted from 3.7V. powered and charged by USB power.
 
 
you can also vote on our official facebook pages, www.facebook.com/FiiOAUDIO

 

[bowei006]

A) i would rather have cheaper device with better sound.

This is only if the e11 solution also works where micca or someone else proivdes a charger and kit. If that is not possible for another battery and charger than option

B)

 

[Tilpo]

The +- 7.4V should be good enough for most headphones.
Let's just take the HD650 as a random example. With a bit of headroom, the reproduced waveform should have a maximum of at least +- 6.5V, that's 9.2V RMS.
The HD650 is rated 103dB at 1V RMS, giving 122dB SPL at 9.2V RMS. That's ear shattering loud.
The HD650 has a rated nominal impedance of 300ohm, which gives us 282mW, this is in fact well above the maximum rated power of the HD650; 200mW.

I think loudness is more than adequate with rail voltages like that on most headphones.

Then the next concern is the quality of the power supply. Putting 6 batteries in series should reduce variation in the rail voltages. But as far as I know most batteries are already pretty darn smooth.
Additionally, and note that I'm no expert on this, a well designed circuit should be able to have a power supply rejection ratio big enough to make the variations in rail voltage that are already small, too small to be audible.

The final point is battery life. I personally think this is more important than that extra 3.4dB SPL. (20*log(11/7.4))
I have no idea how this is better or worse with the 3.7V battery. You'd have to fill me in on this. As well as charge time, but I imagine that option A and B charge faster due to the bigger voltages of the charger (USB voltage is low).

Something I almost forgot, but will option C use the same trick to double the rail supply as the Mini3? That is, an active ground channel? That was the biggest critique on the Mini3, and I would imagine it does indeed affect sound quality. If this is indeed the case, then option B may be a better choice after all, but note that I'm no expert on this.

Finally add in the huge convenience of option C's USB charging. I personally think this is an absolutely huge advantage that should not be underestimated. And especially the inability of option A to be used during charging is a very large minus. I think that it makes option A too inconvenient to be considered. Isn't it possible to change the circuit such that some of the DC adapter's power goes towards the audio circuit as well as charging?

All in all, I think option C is the best, but it does depend on how much sound quality is sacrificed.

Please point out any mistakes I made regarding circuit design, since I am only learning.

 

[bowei006]

That 4 star price sign on option C may make some users...... [size=medium]

ಠ▃ಠ​

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[Tilpo]

That 4 star price sign on option C may make some users...... [size=medium]

ಠ▃ಠ​

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We're talking about a flagship here, bro.

 

[sashaw]

I vote for A. It just easy on you and us to have a user replaceable battery. Less hassel for you guy to replace the battery in the future and we don't need to wait while the amp is sent away.

 

[Tilpo]

I vote for A. It just easy on you and us to have a user replaceable battery. Less hassel for you guy to replace the battery in the future and we don't need to wait while the amp is sent away.

If the battery in option B/C is a standard size, there could actually be the option for on-the-go switching for even longer battery life.
I would be willing to pay extra for such a feature.

(switching 6 AAA batteries on-the-go is not really a good plan, if you think about it)

 

[bowei006]

The E19 was announced so not sure how the E12's amp section will stack up to the E19? How about going with option A for E12 like with E11...so keeping it nice and cheap but POWERFUL and then doing a very good and better but easier to use but more expensive amp section in E19 like E17?
 
The 4 stars may mean double the price?? $200 to $300-$350?

 

[Anaxilus]

I'm waiting to see if Fiio can compete w/ the best out there so I vote sound above all else.  This is a 'flagship' product no?  If you have to ask....
 
As for 7.4V being 'enough', the DACPort had issues at times and it ran 18V.  Going to be tricky designing for both high current, low Z orthos and high Z, high voltage dynamics not to mention managing hiss on IEMs.

 

[bowei006]

Quote:

I'm waiting to see if Fiio can compete w/ the best out there so I vote sound above all else.  This is a 'flagship' product no?  If you have to ask....
 
As for 7.4V being 'enough', the DACPort had issues at times and it ran 18V.  Going to be tricky designing for both high current, low Z orthos and high Z, high voltage dynamics not to mention managing hiss on IEMs.

The E17 and E90K is the current flagship but even then it is not like it will destroy any thousand dollar units. IT is flagship for FiiO. What should matter more is best in it's price class.

 

[Anaxilus]

I thought the E17 was the E11 w/ a DAC?  The E90 is just an E9 I read.  'Flagship' is Fiio's claim, not mine.
 
$100-$200 worth of parts/design is enough to take out a lot of $1000 gear actually.

 

[Tilpo]

I think the fact that you can't use A while charging is just way too inconvenient, especially for a flagship unit. Imo one should never sacrifice convenience for sound quality, especially if the differences aren't huge.

@Anaxilus
Voltage ain't everything. The 9.2V RMS I estimated should be enough, as long as you design it well. Of course you can run out of current and make it clip that way, but I think that's more dependent on the design that on the battery used. Also if the unit is going to operate in full class A mode, then it may be better to get that little bit extra voltage as well. But note that the difference is only 3.4dB, which is not a whole lot.
You don't need to be able to drive an HE-6 with this unit either. As long as it can do well with most (relatively) power hungry cans it's fine.

 

[firev1]

  Come on Fiio, 2 x 3.7V lithium! I know you can do it! 
 
As long as the amp has enough current,  even 7.4V should be more than enough for portable use. Lithium ions have pretty high discharge rates though so its good. Dacport may run 18v but does the usb bus provide enough current? 5V 500ma usb 2.0 is barely enough for some applications(not enough headroom for the focusrite preamps I borrowed recently) and the DACport is running at +/-18V. Frankly I expect the E12 not to be Class A design since if it is, I think it would be promoted in front. I expect a less energy wasting Class B amp instead.  Of course I could be wrong.
 
Frankly I don't expect E12 to do orthos but most dynamics and especially IEMs.

 

[tzjin]

Guys, just count the stars.

A has 10, B has 11, C has 12.
 
 
 
In all seriousness A will be extremely inconvenient. B would be my default, while C would be my top choice if you find there is no significant degradation of sound quality.

 

[bowei006]

Quote:

Guys, just count the stars.

A has 10, B has 11, C has 12.
 
 
 
In all seriousness A will be extremely inconvenient. B would be my default, while C would be my top choice if you find there is no significant degradation of sound quality.

but C might drop out of others choices for having twice the stars of A