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Review and Measurements of New JDS Labs Atom Headphone Amp

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Dec 26, 2018
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I have ordered mine on 17th of December, both the Khadas Tone Board as well as JDS Atom.
Neither had come yet.:D
Just for the info, i ordered Atom on the 31st of December, UPS Worldwide Saver. As for the Khadas Board, ordered on the 26th of Dec, but got an email that it started shipping a only a week ago
 

pwjazz

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While I agree with everything you say, I wonder how audible the distortion at THD+N Ratio of 0.1% is.
Yeah, I have no idea. I doubt that I could pick it up in an ABX test. That said, for someone picking between these two devices, I would recommend going with the one that has the much lower distortion even if it does have a plastic case.

In my case, switching may not be logical, but this is a hobby for me and I grew up close to where JDS builds their stuff, so I like the idea of owning something of theirs too.
 

Roen

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Just for the info, i ordered Atom on the 31st of December, UPS Worldwide Saver. As for the Khadas Board, ordered on the 26th of Dec, but got an email that it started shipping a only a week ago
Who did you order the Khadas board from?
 
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From their official site, EMS shipping
Me too.

Yeah, I have no idea. I doubt that I could pick it up in an ABX test. That said, for someone picking between these two devices, I would recommend going with the one that has the much lower distortion even if it does have a plastic case.
When I had read the JDS Atom review, I knew that's the AMP I was gonna order, I was on the fence though between Atom, LiquidSpark and Magni 3.
 

wadec22

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While I agree with everything you say, I wonder how audible the distortion at THD+N Ratio of 0.1% is.
.1 is -60db, I certainly wouldn't feel comfortable with that number. in the thread with noise test tones, most folks don't have a problem detecting noise at -70db at regular listening levels. .1 is hi distortion in a headphone environment.

In fact if you cross reference my SMSL M10 impressions post (which came out prior to amir's official measurements), distortion in the headphone amplifier was causing me physical listening fatigue at .02 in the balanced output and even lower out of the 1/4" jack.

IMHO - anything higher than -90db distortion in headphone listening is no bueno and a risk of affecting your listening experience.
 

Roen

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.1 is -60db, I certainly wouldn't feel comfortable with that number. in the thread with noise test tones, most folks don't have a problem detecting noise at -70db at regular listening levels. .1 is hi distortion in a headphone environment.

In fact if you cross reference my SMSL M10 impressions post (which came out prior to amir's official measurements), distortion in the headphone amplifier was causing me physical listening fatigue at .02 in the balanced output and even lower out of the 1/4" jack.

IMHO - anything higher than -90db distortion in headphone listening is no bueno and a risk of affecting your listening experience.
Where is the -90 dB mark?
 

pwjazz

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My Atom arrived today. I'm listening to my test playlist at the moment and I'm a happy camper. I asked JDS to add some extra weights to the case and I'm glad I did, it seems a good weight/stability now.

Yes it is plastic, but the volume knob works well enough and being black the whole thing doesn't look too bad.

Now the sound... When setting volume by ear, I start low and gradually turn it up until I hear the clarity and bass slam that I want, then back off a notch. Doing this with the Atom, I was surprised to find myself using low gain when on my Magni 3 I had been using high gain. It turns out that I'm listening about 10 dB SPL(A) lower than I was on the Magni 3! I have to assume that this is due to the lower noise floor and distortion giving me the clarity I seek without having to crank it up. Good news for my enjoyment and my auditory health too :)
 

despoiler

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My Atom arrived today. I'm listening to my test playlist at the moment and I'm a happy camper. I asked JDS to add some extra weights to the case and I'm glad I did, it seems a good weight/stability now.

Yes it is plastic, but the volume knob works well enough and being black the whole thing doesn't look too bad.

Now the sound... When setting volume by ear, I start low and gradually turn it up until I hear the clarity and bass slam that I want, then back off a notch. Doing this with the Atom, I was surprised to find myself using low gain when on my Magni 3 I had been using high gain. It turns out that I'm listening about 10 dB SPL(A) lower than I was on the Magni 3! I have to assume that this is due to the lower noise floor and distortion giving me the clarity I seek without having to crank it up. Good news for my enjoyment and my auditory health too :)
I'm noticing the same thing as you. I don't need as much volume as before because everything is so clear. Given the new amp I decided to re-evaluate Spotify vs Tidal Hifi yesterday. Easy choice. Tidal Hifi sound quality is better. I ditched my Spotify subscription. My ears are so, so happy.
 
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Got mine on 9th, now waiting for Khadas Tone Board to arrive :)

By the way, when the gain button is released, low gain mode is active, right?
Yes, low gain is activated when the button is not pressed in. And high
gain with the button pressed in. You will also know by the audible
difference. Louder with high gain set and lower with low gain set. From
the atom manual[0]:

"Setting Gain
Press the gain button to toggle between low or high gain amplication.
Always use the lowest gain necessary.

Switch to high gain only when you’re unable to achieve desired
listening volume at low gain."

[0] http://www.jdslabs.com/pdf/instructions-atom-amp.pdf
 
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My Atom arrived today. I'm listening to my test playlist at the moment and I'm a happy camper. I asked JDS to add some extra weights to the case and I'm glad I did, it seems a good weight/stability now.

Yes it is plastic, but the volume knob works well enough and being black the whole thing doesn't look too bad.

Now the sound... When setting volume by ear, I start low and gradually turn it up until I hear the clarity and bass slam that I want, then back off a notch. Doing this with the Atom, I was surprised to find myself using low gain when on my Magni 3 I had been using high gain. It turns out that I'm listening about 10 dB SPL(A) lower than I was on the Magni 3! I have to assume that this is due to the lower noise floor and distortion giving me the clarity I seek without having to crank it up. Good news for my enjoyment and my auditory health too :)
Brilliant idea asking for more weights, wish I had done that.
 

emmett

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This looks like it would be a great add-on for my DAP. I have a Pioneer XPD-30r as well as a FiiO x3 2nd gen.
I presume the proper way to utilise it would be to use the 3.5 out of the DAP connected to the Atom's 3.5 input? I have the HD6XX headphones and would appreciate any opinions.

I have been looking for a fully balanced amp but I don't think I would be giving up much or anything using the Atom?
 
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When my sources are plugged into the Atom separately, I'm able to turn it all the way up to max, on high gain, with no noise audible. However, when I add another source into the other input (such as when the shield of the RCA cable touches the input jack), I'm getting an irregular, high-pitched noise that happens even when one of the devices is off.

Is this a ground loop issue? Would a USB isolator or a 3.5mm isolator help?

My sources are:
- Topping D30 (powered by outlet)
- Behringer UMC204HD (USB powered)

Thanks

Edit: The noise gets louder if I turn up the volume on the Atom. The noise is gone if I plug the UMC204HD into a power bank.

Edit 2: Fixed by using a USB splitter (https://www.amazon.ca/gp/product/B0733FH5HR/) to power it by directly connecting to a USB charger on my power bar, and taping off the power pins on the plug that goes into my computer.
 
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How does the crosstalk compare to other alternatives? Dynamic range?
 
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