[surfgeorge]

No I don't, but gave the mojo serious consideration when looking for a dac/amp to slot between the AK70 Mkii & HD660S I'd already purchased. .....

One difficult to absorb thread (This one , post #12) had the post quoted below, which led me to skip the mojo despite it's many positives and aim for a more powerful yet still portable option. The mojo having an output impedance of just 75mOhms shouldn't be enough to drive higher impedance headphones

Thanks for sharing the story of your journey! Sounds very familiar (I started by seeing a cheap headphone amp somewhere a few months ago, and yesterday I summed up my expenses since then, which were well above 1000 Euro...)

About the output impedance:
Not sure how familiar you are with the terms, 75mOhms = 75 mili-Ohms = 0,075 Ohms
So the Mojo fulfills that 1/8 rule for any headphone with an impedance of 0,6 Ohms or higher! That is virtually EVERY headphone or IEM on the market. I think the lowest are in the range of 4 Ohms.

 

[Phronesis]

Can the mojo power a 300Ω (HD800S) set of head phones anywhere above a weak whisper?

Yes, it can drive them to normal volumes. Keep in mind that if a headphone doesn't sound good at higher volume, that doesn't necessarily mean the amp is underpowered, it may just mean that the headphone itself loses composure and sound quality when driven harder, or the sound signature of the headphone just doesn't sound as good at a louder volume. There are multiple variables involved, and the proper way to determine what has what effect is to do systematic comparisons where the only thing changed is what you want to compare.

 

[ZappaMan]

Related to this, when people talk about a headphone being driven with ‘authority’, what is it that gives this authority.

So I was wondering whether there’s more then just voltage/volume in the equation.

With my hd600, Hd800s driven via mojo, it’s always better when it’s louder, but I dont want it so loud that it damages my hearing.

So that had me wondering, if other amps, give authority, without recourse to high volume?

 

[melons]

Thanks for sharing the story of your journey! Sounds very familiar (I started by seeing a cheap headphone amp somewhere a few months ago, and yesterday I summed up my expenses since then, which were well above 1000 Euro...)

About the output impedance:
Not sure how familiar you are with the terms, 75mOhms = 75 mili-Ohms = 0,075 Ohms
So the Mojo fulfills that 1/8 rule for any headphone with an impedance of 0,6 Ohms or higher! That is virtually EVERY headphone or IEM on the market. I think the lowest are in the range of 4 Ohms.

Yes, it can drive them to normal volumes. Keep in mind that if a headphone doesn't sound good at higher volume, that doesn't necessarily mean the amp is underpowered, it may just mean that the headphone itself loses composure and sound quality when driven harder, or the sound signature of the headphone just doesn't sound as good at a louder volume. There are multiple variables involved, and the proper way to determine what has what effect is to do systematic comparisons where the only thing changed is what you want to compare.

Thanks for the steer, but I'm still hesitant to believe a lower powered unit will drive the HD's as well. Ive pasted a comment I read from a rather enthusiastic mojo owner below (taken from Here/Massdrop) which explains rather better than I could my reservations:


iCeOL8TRAmnesia "Yes I recommened it especially at this price so you can hear the best dac youve ever heard(since most people have never heard a hugo, or a dave, or a blu mkII m scaler(highest quality from chord)) but dont expect it to drive big headphones with low end grunt bassy full sound like other dac/amps in this price category really its for portable on ears and iems. Some portables will have full sounding bass but many power hungry full size headphones yeah you will get a hint of bass but other things like iDSD BLACK LABEL(DONT GET THE OLD SILVER ONE GET THE NEW BLACK ONE HAS BLACK PAINT) for 380$(keeps going on deal at Adorama every other month now so just check Slickdeals for the deal) while less precise and less laser like sounding because its not a PULSE ARRAY LIKE CHORD PRODUCTS will sound more full have a fuller low end(not basshead just thick and juicy). Thats about the shortest way to sum it up the Chord Mojo is the god of its form factor its undeniable and yes it will power full size headphones to loud volume its just the sound will not be full on the lower end, that is its major limitaion and yes it is a limitation, but you will never hear a clearer sound out of any other dac than with this one it also has the ability to improve lower quality source material like mp3, but of course truly shines with higher source material(it even makes mp3 listenable on unforgiving headphones like BeyerDynamic T90s but still doesnt clean it up completely so it doesnt make every unforgiving headphone of low bitrate suddenly forgiving but it gets close). Every other Dac on the market besides Chords will play back piano like blurry muddy crap. The only DAC on the market that can play it back clearly hearing each key harmonic seperately is a Chord DAC period except maybe an expensive R2R TotalDAC or something like that which is not portable and super expensive. A chord FPGA DAC is like the audio version of a GPU it has multiple cores heres what Chords Rob Watts(FPGA Genius) said:......"

 

[greatwhite58]

Thanks for the steer, but I'm still hesitant to believe a lower powered unit will drive the HD's as well. Ive pasted a comment I read from a rather enthusiastic mojo owner below (taken from Here/Massdrop) which explains rather better than I could my reservations:


iCeOL8TRAmnesia "Yes I recommened it especially at this price so you can hear the best dac youve ever heard(since most people have never heard a hugo, or a dave, or a blu mkII m scaler(highest quality from chord)) but dont expect it to drive big headphones with low end grunt bassy full sound like other dac/amps in this price category really its for portable on ears and iems. Some portables will have full sounding bass but many power hungry full size headphones yeah you will get a hint of bass but other things like iDSD BLACK LABEL(DONT GET THE OLD SILVER ONE GET THE NEW BLACK ONE HAS BLACK PAINT) for 380$(keeps going on deal at Adorama every other month now so just check Slickdeals for the deal) while less precise and less laser like sounding because its not a PULSE ARRAY LIKE CHORD PRODUCTS will sound more full have a fuller low end(not basshead just thick and juicy). Thats about the shortest way to sum it up the Chord Mojo is the god of its form factor its undeniable and yes it will power full size headphones to loud volume its just the sound will not be full on the lower end, that is its major limitaion and yes it is a limitation, but you will never hear a clearer sound out of any other dac than with this one it also has the ability to improve lower quality source material like mp3, but of course truly shines with higher source material(it even makes mp3 listenable on unforgiving headphones like BeyerDynamic T90s but still doesnt clean it up completely so it doesnt make every unforgiving headphone of low bitrate suddenly forgiving but it gets close). Every other Dac on the market besides Chords will play back piano like blurry muddy ****. The only DAC on the market that can play it back clearly hearing each key harmonic seperately is a Chord DAC period except maybe an expensive R2R TotalDAC or something like that which is not portable and super expensive. A chord FPGA DAC is like the audio version of a GPU it has multiple cores heres what Chords Rob Watts(FPGA Genius) said:......"

Well that’s one persons view but I totally disagree. As I said it drives my 300 Ohm HD650 easily and I have it no where near full volume. As for the bass well it is the best that I have heard through my HD650’s. My previous set up was Audioquest Dragonfly Black the red and the Mojo is better in my opinion.

 

[melons]

Well that’s one persons view but I totally disagree. As I said it drives my 300 Ohm HD650 easily and I have it no where near full volume. As for the bass well it is the best that I have heard through my HD650’s. My previous set up was Audioquest Dragonfly Black the red and the Mojo is better in my opinion.

After reading the scribblings of iCeOL8TRAmnesia especially his piano comments it has become a horrible realisation to me that I will have to audition a mojo & hugo at some stage, the 'horrible' being the potential additional financial outlay. This is getting to be an expensive pastime

 

[dontfeedphils]

After reading the scribblings of iCeOL8TRAmnesia especially his piano comments it has become a horrible realisation to me that I will have to audition a mojo & hugo at some stage, the 'horrible' being the potential additional financial outlay. This is getting to be an expensive pastime

If it makes you feel any better, you're drastically overthinking it, and can definitely enjoy them from a Mojo.

 

[Phronesis]

I totally understand how, intuitively, it makes sense that having extra power will improve sound by exerting more 'control' and 'authority' over drivers. If your car has extra power, it can accelerate faster, get up hills easier, etc. If your muscles have extra power, you can perform better in sports. But these analogies are misleading because the job of an amplifier isn't to exert some general sort of control, but only to amplify a signal in a linear way. Once an amplifier has enough power to do that (accounting for transients and allowing some headroom for safety margin), there's nothing more or better the amp can do; linear is the best we can do, and anything other than linear would represent distortion. Any excess power beyond what's needed for linear amplification is never used, and should never be used. If you need to throw a ball 100 feet, you need to use exactly the power required to do that, no more and no less.

It's quite easy to convince ourselves that extra power is improving sound because that's what we expect to happen, but we can find out if we're getting better sound by doing proper back to back comparisons. When I've done such comparisons, I was surprised to find that I could no longer notice the differences I previously thought I heard. It was very eye opening … err, ear opening.

 

[TKpurple]

I would also suggest checking both Mojo and Hugo 2. I am using somehow "hated" mojopoly and I prefer it sound signature and clarity over Hugo 2 driven by Fiio x 5 first gen in particular for rock music material. Maybe I am party deaf or inexperienced but I would not say the differences I hear are always "night and day" in favour of more expensive gear.

 

[ZappaMan]

I totally understand how, intuitively, it makes sense that having extra power will improve sound by exerting more 'control' and 'authority' over drivers. If your car has extra power, it can accelerate faster, get up hills easier, etc. If your muscles have extra power, you can perform better in sports. But these analogies are misleading because the job of an amplifier isn't to exert some general sort of control, but only to amplify a signal in a linear way. Once an amplifier has enough power to do that (accounting for transients and allowing some headroom for safety margin), there's nothing more or better the amp can do; linear is the best we can do, and anything other than linear would represent distortion. Any excess power beyond what's needed for linear amplification is never used, and should never be used. If you need to throw a ball 100 feet, you need to use exactly the power required to do that, no more and no less.

It's quite easy to convince ourselves that extra power is improving sound because that's what we expect to happen, but we can find out if we're getting better sound by doing proper back to back comparisons. When I've done such comparisons, I was surprised to find that I could no longer notice the differences I previously thought I heard. It was very eye opening … err, ear opening.

I don’t want to stray off topic, but are you Saying, the concept of ‘authority’ is meaningless, and we should just consider the thing as - can the amp play it without distorting it?
I wonder why people talk about authority thanks for the point of view.

 

[surfgeorge]

........ the job of an amplifier isn't to exert some general sort of control, but only to amplify a signal in a linear way. Once an amplifier has enough power to do that (accounting for transients and allowing some headroom for safety margin), there's nothing more or better the amp can do; ......

I think that is a too stark simplification of the job of an amplifier. Linearity is an important property, as is control and power, noise and distortion.
Based on my (limited) understanding of electronics and acoustics there are other factors than just linearity and power (current) at play.
The distortion, being one important characteristic, and one that is getting higher (worse) the closer the amp is getting to it’s limits, so a more powerful amp should have less distortion at the same load, all else being equal.
The impedance, which acts as a damping force for the headphone’s membrane, and therefore has a big impact on accuracte reproduction of sound.
Then there is the stability of supply voltage, which leads to noise and strongly depends on the amplifier design.
And I am sure there’s more than those points.

The good news is that the Mojo is doing very well in all these aspects.

 

[Phronesis]

I don’t want to stray off topic, but are you Saying, the concept of ‘authority’ is meaningless, and we should just consider the thing as - can the amp play it without distorting it?
I wonder why people talk about authority thanks for the point of view.

I think 'authority' is a general perception which is a function of the music itself, volume level, headphones, extent and nature of our attention when listening, etc. IMO, it's fine to invoke the concept of authority to describe what we perceive, just as we use words like dynamic, energetic, clear, veiled, punchy, bright, distant, forward, etc. These words don't have precise meanings, but they help us communicate. And if an amp is truly underpowered, I can see that reducing the sense of 'authority' because dynamic range could be audibly compromised and audible distortion could be introduced. But if an amp has enough power, I don't see how another amp with more power could add authority.

 

[Sonic Defender]

Louder if at an acceptable personal amplitude and not distorted will be perceived as sounding better. That is how our brains are wired. Most devices have at least some colouration they add to the sound, again, to varying degrees, and we have preferences to varying degrees. Our preferences also change over time, and may shift back and forth over the years so what we respond to today may be different than it was 4 years ago and it may be different 2 years from now. Ultimately the less colour a source or amp adds to the signal the better as in theory it allows you to hear the signature of the headphone more. As with speakers, headphones should have the greatest perceptible impact on the sonic signature of our system and when people are describing the sound of their chain, hopefully it is mostly the transducer and source material that they are describing. If the DAC or amp are inflecting so much added colour that could be construed as a negative, but it doesn't have to be either, it is all subjective. I believe it doesn't matter how we arrive at the sound that we love, as long as we get there.

 

[Phronesis]

I think that is a too stark simplification of the job of an amplifier. Linearity is an important property, as is control and power, noise and distortion.
Based on my (limited) understanding of electronics and acoustics there are other factors than just linearity and power (current) at play.
The distortion, being one important characteristic, and one that is getting higher (worse) the closer the amp is getting to it’s limits, so a more powerful amp should have less distortion at the same load, all else being equal.
The impedance, which acts as a damping force for the headphone’s membrane, and therefore has a big impact on accuracte reproduction of sound.
Then there is the stability of supply voltage, which leads to noise and strongly depends on the amplifier design.
And I am sure there’s more than those points.

The good news is that the Mojo is doing very well in all these aspects.

Linearity isn't just another property of an amp, it's the goal of an amp, and is achieved by having enough voltage capability, current capability, power, etc. The job of an amplifier is to linearly scale up a signal by a desired amount, without otherwise changing the signal, hence the term 'amplifier'.

Maybe a Chord rep can chime in here and tell us about the amp specs of the Mojo, the headphones it can drive with negligible distortion, etc.

 

[Sonic Defender]

But if an amp has enough power, I don't see how another amp with more power could add authority.

I tend to agree and I think ultimately people are responding to the subjective side of preference more often than not, and less to the technical side of out and out ability to drive a load. I don't dispute that some people are so good with tuning a device that when they do shift the signature from linearity they do so in a very musical deviation that for many will be perceived as pleasant. I do; however, agree with the substance of your post very much.