[miketlse]

Is there any way to *reset mojo *?

Reset mojo to what? The only things that you can reset are the battery management circuit, and the line-out voltage, and neither of those will help you.
Just to make sure that all the simple potential root causes have been checked, before you send your Mojo back:

• Do all your phones have OTG capability?
• Are your phones/computer setup to output music via USB?
• Are your music player apps setup to output music via USB?

 

[musickid]

when using mojo line out with a tube amp how do you know for certain whether to use 3v or 1.9v?

thanks mk

 

[NaiveSound]

Reset mojo to what? The only things that you can reset are the battery management circuit, and the line-out voltage, and neither of those will help you.
Just to make sure that all the simple potential root causes have been checked, before you send your Mojo back:

• Do all your phones have OTG capability?
• Are your phones/computer setup to output music via USB?
• Are your music player apps setup to output music via USB?

Yes to all of them. In that past it worked and now it doesn't.... damn

 

[NaiveSound]

Just found out something about my mojo problem.

When I first turn mojo on and plug it in a source, the power button colors up.

But if I unplug it from the source and then plug it back in Thr power button does not color up....does that diagnose

 

[DivaFonda]

Does anything happen if you jiggle the cord plugged into it? If so, I do think the port may have gone bad. I don't own this yet, but I've seen power ports go bad on other devices. It works for a second then because something is loose, the connection is lost.

 

[Jawed]

The Mojo's listed THD is 0.00017%. That's absurdly low.

That's not when driving headphones though, that'll be into a load of 10K ohm or 100K ohm. Into headphones distortion increases.

I would be interested in seeing objective evidence for distortion caused by Chord's DAC/amps as opposed to the headphones themselves.

I don't know of any such published results.

naturally sounds "phatter" and more powerful when you turn up the volume, anyway.)

Except that when playing DAVE at the same volume on the same piece of music it was not "phatter". That was the entire point of my posting, that compared with DAVE, TT (and, I expect Mojo) will be perceptibly distorted at "normal" listening levels into apparently easy to drive headphones, such as HD 800 S.

Now playing: Low - Do You Know How to Waltz?

 

[Music Alchemist]

That's not when driving headphones though, that'll be into a load of 10K ohm or 100K ohm. Into headphones distortion increases.

What I'm saying is that headphones have much higher distortion in the first place, so we don't know how much of that is caused by the DAC/amp.

Except that when playing DAVE at the same volume on the same piece of music it was not "phatter". That was the entire point of my posting, that compared with DAVE, TT (and, I expect Mojo) will be perceptibly distorted at "normal" listening levels into apparently easy to drive headphones, such as HD 800 S.

Okay, but as I stated, I got no noticeable distortion driving the HD 800 from the Mojo, and it was hardly different from using very powerful amps that cost thousands.

Also, you're comparing two different DACs. For all you know, it could be the DAC that made the difference, not the difference in output power.

 

[Jawed]

Also, you're comparing two different DACs. For all you know, it could be the DAC that made the difference, not the difference in output power.

No, because when I turned down the volume on TT, the phatness disappeared. And when I turned down the volume on DAVE there was no change in phatness. And when I turned up the volume on DAVE there was no change in phatness either. TT's sound was changing with volume, not DAVE.

DAVE just has lower distortion at the same listening levels.

Now playing: Beneath Autumn Sky - Zealots Awaken

 

[Music Alchemist]

No, because when I turned down the volume on TT, the phatness disappeared. And when I turned down the volume on DAVE there was no change in phatness. And when I turned up the volume on DAVE there was no change in phatness either. TT's sound was changing with volume, not DAVE.

DAVE just has lower distortion at the same listening levels.

And that lower distortion could come from its design (it certainly has lower measured distortion) rather than the fact that it has more output power.

The DAVE only outputs up to 154 mW at 300 ohms anyway. That's less than plenty of $100 headphone amps. And the HD 800 gets up to 600 ohms at some frequencies. All this isn't that relevant, though, because to reach 110 dB, the HD 800 only needs roughly 21 mW at 300 ohms. (Sure, it's 210 mW for 120 dB, but it's doubtful you'd ever get that loud, even with dynamic peaks.)

There just isn't any credible evidence that supports the notion that having excess power does anything at all to the sound, as long as the amp meets the basic requirements. (Which I linked to before.) If there is a difference in sound with a particular amp or DAC/amp and all of them have enough power for the headphone to reach the desired SPL, the difference must come from other aspects of the design aside from output power.

 

[NaiveSound]

Does anything happen if you jiggle the cord plugged into it? If so, I do think the port may have gone bad. I don't own this yet, but I've seen power ports go bad on other devices. It works for a second then because something is loose, the connection is lost.

Nothing happens when I move the cord around. But when I plug the cord in it the power button ball lights up (if I unplug and then plug back it the power ball does not color up).

So if it does color up when I first plug it in, doesn't this mean connection of some sort is made?

Mr Rob Watts, plz help

 

[Jawed]

And that lower distortion could come from its design (it certainly has lower measured distortion) rather than the fact that it has more output power.

That's the point: when you take the same basic design and improve it with less distortion at the same power, it sounds better Usually, at the same amount of distortion, this new design will have more power.

There just isn't any credible evidence that supports the notion that having excess power does anything at all to the sound, as long as the amp meets the basic requirements. (Which I linked to before.)

I have already said that I once would have agreed with you, because according to the specifications of TT, there is no way this kind of distortion would be heard at normal listening levels with HD 800 S.

Then I compared it to DAVE and heard that at the same level, TT sounds distorted (it's subtle, 1 in 50 tracks where you'd notice), simply because it is being played loudly. Turn TT down a little and the distortion disappears. DAVE didn't show this distortion, even when I played the music more loudly.

If there is a difference in sound with a particular amp or DAC/amp and all of them have enough power for the headphone to reach the desired SPL, the difference must come from other aspects of the design aside from output power.

The specification for power is for a given amount of distortion. So two amps that can both deliver the same power will not necessarily have the same distortion when delivering that power. The amp with the worst distortion at the same power level will tend to sound worse.

As I say, I used to have the same point of view as you, that for "normal listening" SPL, headphones like HD 800 S aren't fussy if the amp is more than powerful enough, like TT. But it turns out that the distortion levels for headphone amplification specification are too generous... It's subtle, but I think it's unfair to suggest that more power (or less distortion at the same power) makes no difference.

TT and Mojo are about the same power for the same amount of distortion and so with headphones like HD 800 S there will be some pieces of music at normal listening levels where distortion will be heard, varying with volume level. Upgrading to DAVE (or perhaps Hugo 2, which also has lower distortion, I believe) will not show the same variation in distortion at these volume levels.

Now playing: Les Mysteres des Voix Bulgares

 

[Music Alchemist]

That's the point: when you take the same basic design and improve it with less distortion at the same power, it sounds better Usually, at the same amount of distortion, this new design will have more power.

I have already said that I once would have agreed with you, because according to the specifications of TT, there is no way this kind of distortion would be heard at normal listening levels with HD 800 S.

Then I compared it to DAVE and heard that at the same level, TT sounds distorted (it's subtle, 1 in 50 tracks where you'd notice), simply because it is being played loudly. Turn TT down a little and the distortion disappears. DAVE didn't show this distortion, even when I played the music more loudly.

The specification for power is for a given amount of distortion. So two amps that can both deliver the same power will not necessarily have the same distortion when delivering that power. The amp with the worst distortion at the same power level will tend to sound worse.

As I say, I used to have the same point of view as you, that for "normal listening" SPL, headphones like HD 800 S aren't fussy if the amp is more than powerful enough, like TT. But it turns out that the distortion levels for headphone amplification specification are too generous... It's subtle, but I think it's unfair to suggest that more power (or less distortion at the same power) makes no difference.

TT and Mojo are about the same power for the same amount of distortion and so with headphones like HD 800 S there will be some pieces of music at normal listening levels where distortion will be heard, varying with volume level. Upgrading to DAVE (or perhaps Hugo 2, which also has lower distortion, I believe) will not show the same variation in distortion at these volume levels.

Just because it has lower distortion does not mean that the higher maximum output power available is the cause.

It's all about the design of the electronics, not how much power they have in reserve.

I tend to listen loud...and to all types of music...and never encountered (obvious) distortion with the HD 800 driven by the Mojo. The fact that it sounded roughly the same from amps with a lot more power (and at far higher price points) supports my assertion that having more power available (that the headphone would never use unless you increase the volume) has no benefit.

I don't doubt your experiences; only some of your explanations as to the cause.

 

[435279]

Nothing happens when I move the cord around. But when I plug the cord in it the power button ball lights up (if I unplug and then plug back it the power ball does not color up).

So if it does color up when I first plug it in, doesn't this mean connection of some sort is made?

Mr Rob Watts, plz help

You will have to return it to your dealer for service, something has broken in there. Rob can't/won't help he is not Chord customer services.

YOUR ONLY OPTION AT THIS POINT IS TO RETURN IT.

 

[Yourmomm]

You will have to return it to your dealer for service, something has broken in there. Rob can't/won't help he is not Chord customer services.

YOUR ONLY OPTION AT THIS POINT IS TO RETURN IT.

+1

Unless you bought a duff cable, time to send it in...

 

[Arpiben]

Just found out something about my mojo problem.

When I first turn mojo on and plug it in a source, the power button colors up.

But if I unplug it from the source and then plug it back in Thr power button does not color up....does that diagnose

Not sure I am understanding you well.
But,in principle, if power ball turns up and stays on it means that USB handshake protocol has been done and it is ok. You should be able to play music from your source.
When dealing with USB OTG cables & Android phones MOJO must be On first.
When dealing with computers it is more or like 'plug & play' and it should not matter.
If not already done, I will suggest you to limit first your USB trials with a windows7 PC.