[zilch0md]

Hi,

In your analysis, you didn't take into account that amps of those voltages probably are using op-amps that do not swing rail-to-rail. That's probably going to knock off several volts from the max power supply voltage.

I hear you. That might explain why RSA (more conservatively?) claims a swing of 12 to 14V single-ended with the SR-71B (even though its 4-cell internal battery delivers up to 16.8V when fully charged).

I really have no idea what inefficiencies are involved and I agree that we can't assume that single-ended swing will always equal the supply voltage, nor balanced swing twice the supply voltage, but there is at least a proportional relationship between the two, up to some finite limit set by the opamps in use as you've said, or some other limiting design factor.

Still, with iBasso claiming a swing of 32V for balanced output, it seems certain they couldn't claim a higher figure with a maximum supply voltage of 16V. And there's no way the PB2 enjoys a swing of 32V balanced when using the fully charged three-cell 12.6V internal battery (where, at best, swing in balanced mode would be 25.2V, falling to 18.0V as the battery discharges.

What I take from all of this is that your supply voltage can make a BIG difference. There are several respected posters in the PB2 threads who have said PB2 performance is at its best when used with the 16V AC adapter. That's all I need to know to want a portable (transportable) 16V supply for the PB2 (i.e. XP8000 + WI16 regulator).

I've already reaped the benefits of this approach by powering the Meier Stepdance with its maximum permissible 15V supply voltage yielding much improved dynamics and bass control vs. using an internal 9V battery. A bunch of people have joined the 15V Stepdance cult.

Convenience be gone - I want performance.

 

[justin w.]

i agree that voltage output is usually the limiting factor in performance of a portable amp, and it's rarely even an advertised spec.

 

[zilch0md]

Hi DNZGamer,

Actually, price is an issue for me!

I went 18 months depriving myself of any upgrades before springing for the PB2 and balanced Silver Poisons, recently. The L3 and SR-71B were out of the question, for me.

I'm not familiar with the Arrow offerings - Now I'm afraid of what I'll learn when I read up on them.

Mike

 

[Lorspeaker]

O2................heard it for a few hours..., giant killer of a tiny amp...dunno much about it or how u are gonna get it...
but from what i heard, i think its worth exploring.

 

[DNZGamer]

 

Hi DNZGamer,
Actually, price is an issue for me!
I went 18 months depriving myself of any upgrades before springing for the PB2 and balanced Silver Poisons, recently. The L3 and SR-71B were out of the question, for me.
I'm not familiar with the Arrow offerings - Now I'm afraid of what I'll learn when I read up on them.
Mike

 
 
Ah, well then the Arrow 4G is priced a bit under the RSA amps at $300 flat with shipping and tax included. I honestly did not find the flagship portable RSA amp all that impressive, especially for its size. 
 
Not sure about what your budget is now but for $300, there is very little that could possibly trump the Headstage Arrow (this is my impression from reading a lot of reviews and comparisons before purchasing it myself). Depending on your cans, you may also really appreciate bass boost or treble boost or both. It is done extremely naturally and does not create distortion like other amps.
 
Some of the most attractive features may be a bit irrelevant to you though. The 4G model can power a can like the HD650 for 30 hours or more and IEMs will go for up to 80 hours. It can charge and play at the same time so you can use it as your setup station. It automatically powers on and off according the the presence or absence of an input signal. The amp is really small and light, which I know you said wasn't a concern, but why have something bigger than it needs to be? I have no idea what RSA amps are packing in those boxes but the headstage offers just as much in a smaller form factor. 
 
It has inputs on both ends of the device so when moving, you can plug them into the same side or when stationary, you can have the input coming from the opposite side of your output devices. The device itself also can power two channels at a time and can power two low impedance cans without even the slightest degradation. 
 
Pretty much a neutral amp and will be passing your signal through with clarity, more power and body. Do not even concern yourself with it power wise. It will handle an HD650 easily and I even powered an HD800 to deafening volumes with the zero gain setting. Great amp to pass through a neutral signal and enhance the sound stage while adding power and body to your sound and has 3 settings for bass and treble if you want some more energy, some more body to the mid range or just want to enhance and pronounce a thumpin' beat. 
 
Value wise, an amazing amp imo but I am sure there are plenty of people who will chime in with their own experiences. I've only used a few amps myself (Fiio e6, Fiio E11, Ray Samuels Hornet, RA-1 and the Headstage Arrow). Also there are people probably with much better trained ears who will probably tell you the differences between amps better than me. 

 

[zilch0md]

Hey Justin,

It just occurred to me to ask you something that's a bit off topic but I'm dying to know: What benefit do buffers serve in an amp like the PB2?

I'm asking because in his review of the PB2, Mike (Headphonia) wrote that replacing the PB2's buffers with the iBasso-supplied dummy buffers can actually improve SQ with some op-amps.

Thanks!

Mike

-----------------------------------------------------------------------------------------------------------------------------------------------

Update - an answer to my own question: (I know more than I did two months ago!)

The buffer stage of a PB2 can be thought of as the current gain stage, where the L/R stage is the voltage gain stage. The "power" seen by the headphones is a product of both current gain and voltage gain. You can get to any particular number of Watts RMS per channel using a combination of low current and high voltage or by using a combination with low voltage and high current, but "power-hungry" planar headphones, like the HCE-6 or LCD-2 are current-hungry, not voltage-hungry, where "power-hungry" dynamic headphones, like the HD650, don't care so much whether the power comes from current gain vs. voltage gain.

Thus, even though iBasso provides dummy buffers for use with the PB2, and even though you'll hear slightly greater detail and transparency when running the PB2 with dummy buffers, you'll be forfeiting a lot of current gain that could be had using something other than dummy buffers, but especially so with the likes of HA5002 buffers (each providing 200mA of output current) - available from Head-Fi member HiFlight, in his Topkit for PB2.

More info regarding the PB2's "2500 mW" specification: The only way you're going to get anywhere near this is to supply the amp with 16V external power - either with the included AC adapter, an equivalent power supply, or with an external 16V battery pack, like the Energizer XP8000 with Willy Cable WI16 (a 16V inline voltage regulator cable that reduces the voltage from the XP8000's 19-21V output jack to a constant, regulated 16V.) The PB2's internal 12.6V battery (which drops to lower voltages during use) cannot drive any of the available op-amps/buffers at their rated maximum possible output voltages or currents.

Currently, I'm using the PB2 with LT1678 op-amps, biased to Class A, and HA5002 buffers - all available with HiFlight's TopKit for PB2 - running balanced with Toxic Cables' Silver Poison to LCD-2 rev.1 - all of it powered by the XP8000 with WI16 cable. Amazing sound from a portable amp!





Mike

 

[DNZGamer]

 
Quote:

O2................heard it for a few hours..., giant killer of a tiny amp...dunno much about it or how u are gonna get it...
but from what i heard, i think its worth exploring.

 
I just had a fellow head-fier tell me to build an amp a few weeks ago. Was tempting but the idea of building my own is still kind of intimidating. 

 

[zilch0md]

O2................heard it for a few hours..., giant killer of a tiny amp...dunno much about it or how u are gonna get it...
but from what i heard, i think its worth exploring.

Here it is, preassembled and ready for use:

www.jdslabs.com/item.php?fetchitem=O2Full

 

[zilch0md]

Thanks DNZGamer! You've really whetted my appetite. I'll be searching for more reviews now.

 

[proton007]

Sorry to spoil the party guys, but there's no such thing as a 'more powerful' amp for a headphone. 
A headphone will take whatever power it needs as long as the amp can supply it. Even if the amp is capable of 10x more, or 2x more, it doesn't make any difference.

 

[DNZGamer]

No problem. Just keep in mind the differences between each version. Apparently the 4Gs are a bit better amp wise compared to older models but I think the real difference will be the change in the EQ settings and battery life. Older models seem to have half the battery life of the 4G. 3G bass boost is I think 9dB and 9+9dB (huge bass boost!) where the 4G is 3dB and 9dB. The 3G also does not have a treble boost at all, which imo is a great feature, especially for a lot of the vocals. I almost have it permanently on when using the UM3x which is a bit treble light compared to how I like it. Some people just want bass though and if you are a bass head and want 18 dBs of bass boost then go with the older models.
Quote:

Thanks DNZGamer! You've really whetted my appetite. I'll be searching for more reviews now.

 
 

 

[justin w.]

 
Quote:

Sorry to spoil the party guys, but there's no such thing as a 'more powerful' amp for a headphone. 
A headphone will take whatever power it needs as long as the amp can supply it. Even if the amp is capable of 10x more, or 2x more, it doesn't make any difference.

 
Most of these amps will start to have gobs of distortion if you get anywhere near their 'max power'

 

[DNZGamer]

Well that is because you are destroying your ears if you approach anything close to max volume on these amps... 50% volume, gain 1 on a headstage arrow for HD650 is enough. 

 

[zilch0md]

Sorry to spoil the party guys, but there's no such thing as a 'more powerful' amp for a headphone.
A headphone will take whatever power it needs as long as the amp can supply it. Even if the amp is capable of 10x more, or 2x more, it doesn't make any difference.

I get your point - a 100 Watt light bulb only pulls 100 Watts whether the circuit can support 1000 Watts or 10,000 Watts, but you made a conditional statement: "...as long as the amp can supply it."

If a given amp cannot supply the power a given headphone demands, you'll need a "more powerful" amp. My iBasso PB2 is "more powerful" than the amp in my Sanza Clip when driving my LCD-2, but perhaps not when driving the earbuds that came with the Clip. Thus, there is such a thing as a "more powerful" amp for a headphone that demands more than what a "less powerful" amp can provide.

Party on!



Mike

 

[proton007]

 
Quote:

I get your point - a 100 Watt light bulb only pulls 100 Watts whether the circuit can support 1000 Watts or 10,000 Watts, but you made a conditional statement: "...as long as the amp can supply it."
If a given amp cannot supply the power a given headphone demands, you'll need a "more powerful" amp. My iBasso PB2 is "more powerful" than the amp in my Sanza Clip when driving my LCD-2, but perhaps not when driving the earbuds that came with the Clip. Thus, there is such a thing as a "more powerful" amp for a headphone that demands more than what a "less powerful" amp can provide.
Party on!

Mike

 
99% of the portable amps out there can easily work with headphones upto 600 Ohms. Plenty of power, no need to worry. If you have any doubts as to how much power you need, and you're not afraid of doing the calculations yourself, you can take a look at the thread link below. I've tried to consolidate these concepts.
Take note that I said *amps* not portable media players. There's a reason pmp's use low impedance earphones.