Review and Measurements of New JDS Labs Atom Headphone Amp

[nyxnyxnyx]

https://diyaudioheaven.wordpress.com/headphones/measurements/akg/k501/

It is a bit similar to the KSC75/PortaPro.
Work great at 'normal' listening levels but fall apart at higher levels.
Experimented quite a lot with it.

Just wondering , do we have a chatroom or discord server where i can join?
I'd love to learn and understand more about various things but i don't want to dilute this thread

 

[Veri]

How do you know this?

Solderdude wrote and did a lot of measurements at diyaudioheaven

 

[BDWoody]

Just wondering , do we have a chatroom or discord server where i can join?
I'd love to learn and understand more about various things but i don't want to dilute this thread

This is a very active forum. Don't be afraid to post new threads with any questions...lots of very well informed people around that are happy to help.

It doesn't dilute a thread if you start it...

 

[flipflop]

https://diyaudioheaven.wordpress.com/headphones/measurements/akg/k501/

I don't see how that answers my question. Can you quote the relevant part(s)?

 

[solderdude]

I don't see how that answers my question. Can you quote the relevant part(s)?

You asked how I know that about K501.
I owned it, measured it, played with it listened to it and posted my results so from experience.
That is my K501 (or was, sold it quite quickly again) and that's how I know.

 

[peterq]

I wonder did anybody try to bridge two atom and use it at mono mode with external volume control? I asked JDS but they didn't give me clear answer just said this is possible.

 

[Veri]

I wonder did anybody try to bridge two atom and use it at mono mode with external volume control? I asked JDS but they didn't give me clear answer just said this is possible.

If you use both at max volume and with digital volume control, then use them as mono amplifiers over TRS plugs, then yes, it's possible. Practical? Not really due to its stereo design. But definitely possible.

 

[peterq]

Thx, but the atom doesn't has bridge mode switch as traditional amplifier, the connection in your description is only using one channel, am I correct? Because atom has very low output impedance and if it can work in bridge mode, we can double the output power with only $200, this will be a very good solution.

 

[jak]

Here is a zoomed shot of the power supply:

View attachment 17618

This power supply is monstrous. It weighs more than a Fiio K5 Pro and its power supply together, and consumes 3W without the amp connected to it. Wow. Amp connected but off is 3.2W, on but idle is 5.8W.

For comparison, the K5 Pro measures 0W off, and 3.5 idle.

 

[jak]

This power supply is monstrous. It weighs more than a Fiio K5 Pro and its power supply together, and consumes 3W without the amp connected to it. Wow. Amp connected but off is 3.2W, on but idle is 5.8W.

For comparison, the K5 Pro measures 0W off, and 3.5 idle.

I wonder how this can be sold in the EU, as it violates standby power regulations that mandate a maximum standby power usage of 0.5W.

 

[L5730]

This power supply is monstrous. It weighs more than a Fiio K5 Pro and its power supply together, and consumes 3W without the amp connected to it. Wow. Amp connected but off is 3.2W, on but idle is 5.8W.

For comparison, the K5 Pro measures 0W off, and 3.5 idle.

I'll be that guy - I wonder if they put lead weights in the PSU to give it more heft like they did with the amp

As for standby power, I guess it depends on how standby and off are defined. We've a Panasonic DVD-RW/HDD recorder (Sstandard Def, so it's old ish) and that has two off modes. One that uses quite a lot of power, just a bit less than in normal operation. The other off mode spins down the HDD and turns off the tuners etc. It takes it some time to come back awake from the full standby, much more than a VCR, but it does keep it around that 1/2 watt consumption when in full sleepy standby mode.

 

[douce]

Well I just picked up one of these little guys and not only am I impressed with its performance as a headphone amplifier, but I just spent time A/B'ing it as a pre-amplifier against my Musical Fidelity A3CR Pre and through several tracks it was either indistinguishable between the two or the Atom might have been ahead in terms of flat response and extension.
Considering the 30lb dual monaural pre that cost a couple grand in its day to the Atom's 99usd speaks to its engineering and value, so happy I picked one up!!
Thanks again Amirm for all the work you put into this site.

 

[Kajinski]

Hi, I have some very basic questions as a complete newbie to this game. I have a nice vinyl turntable set up which I run through a Lehmann Black Cube phono pre amp to a Dared valve amp. I have been very happy with that set up but recently have been looking to hook headphones up. There is no jack port on the Dared amp so I have come to the conclusion that I may need a specific headphone amp.

Am I correct in thinking that I can run my turntable via my phono pre amp into say this Atom amp and so to the headphones? I notice the majority of posts are about DACs and DAPs via this unit and not turntables so I wanted to check that this was possible.

I am interested in the Atom amp as it is currently available in the UK whereas the other celebrated amps the Massdrop THX and the new Monoprice are on backorder from the US and its unclear if they would reach in the UK except after waiting months and possible never. Am I missing much choosing the Atom now and not waiting to see about eventual availability of THX and Monoprice?

I reached this forum via reading about the Dark Voice headphone amp, I was initially drawn towards a valve set up as my main speaker amp is valve and I have enjoyed the sound valves give but reading has now suggest that these Atoms may be better than DarkVoice at least for headphones.

It is mainly rock and jazz I listen to, and I have a set of AKG K550s which I run from a Chinese DAP ZiShan DSD which I have been listening to more and more but want to get my vinyl collection into the game once more.

Its a steep learning curve trying to get my head round the more scientific approach from this forum, but am learning a lot as I go.

 

[L5730]

Hi, I have some very basic questions as a complete newbie to this game. I have a nice vinyl turntable set up which I run through a Lehmann Black Cube phono pre amp to a Dared valve amp. I have been very happy with that set up but recently have been looking to hook headphones up. There is no jack port on the Dared amp so I have come to the conclusion that I may need a specific headphone amp.

Am I correct in thinking that I can run my turntable via my phono pre amp into say this Atom amp and so to the headphones? I notice the majority of posts are about DACs and DAPs via this unit and not turntables so I wanted to check that this was possible.

I am interested in the Atom amp as it is currently available in the UK whereas the other celebrated amps the Massdrop THX and the new Monoprice are on backorder from the US and its unclear if they would reach in the UK except after waiting months and possible never. Am I missing much choosing the Atom now and not waiting to see about eventual availability of THX and Monoprice?

I reached this forum via reading about the Dark Voice headphone amp, I was initially drawn towards a valve set up as my main speaker amp is valve and I have enjoyed the sound valves give but reading has now suggest that these Atoms may be better than DarkVoice at least for headphones.

It is mainly rock and jazz I listen to, and I have a set of AKG K550s which I run from a Chinese DAP ZiShan DSD which I have been listening to more and more but want to get my vinyl collection into the game once more.

Its a steep learning curve trying to get my head round the more scientific approach from this forum, but am learning a lot as I go.

The Phono Pre-amp will apply the RIAA Equalisation curve and amplification to bring the stylus signal up to line level. Plugging the outputs of the pre-amp into the Atom should work fine.
However, I think someone more knowledgeable should chime in here as (1) there might need a ground connection for the phono pre-amp to the turntable? (2) What's the deal with the DC-couple issue (lack DC offset protection) and how would that apply to connecting to a vinyl setup? (3) That phono pre-amp output impedance is 47 ohms and mentions output sensitivity 0.775v @ 0dB, how would the output signal interact with the Atom input?
Contacting JDS Labs themselves may be able to provide the answer you need.

I've noticed that the UK retailer has put the price up £20 in the last couple of days. Probably so that they can drop it back for the 11/11 sale

 

[solderdude]

(2) What's the deal with the DC-couple issue (lack DC offset protection) and how would that apply to connecting to a vinyl setup? (3) That phono pre-amp output impedance is 47 ohms and mentions output sensitivity 0.775v @ 0dB, how would the output signal interact with the Atom input?
Contacting JDS Labs themselves may be able to provide the answer you need.

I've noticed that the UK retailer has put the price up £20 in the last couple of days. Probably so that they can drop it back for the 11/11 sale

The Atom is not DC coupled from input to output so a DC on the input will not result in a DC output.

Most likely the price is increased because of the upcoming Brexit.

 

[Veri]

There's also some open box deals though. 99quid
http://www.hifiheadphones.co.uk/jds_labs.html

 

[L5730]

The Atom is not DC coupled from input to output so a DC on the input will not result in a DC output.

Ah. I don't understand this stuff, but I somehow got the impression there was potential for damage if something rare went wrong. But hey, that's life!

There is no problem connecting the phono out to the Atom. However, one will need to use the high gain setting.

That should do the job for @Kajinski

Most likely the price is increased because of the upcoming Brexit.

Don't even get me started! The whole thing is a big and now a general election!

 

[solderdude]

Ah. I don't understand this stuff, but I somehow got the impression there was potential for damage if something rare went wrong. But hey, that's life!

There are 2 separate things in this DC story.
1: When an amplifier is purely DC coupled AND the device connected to such an amplifier has a DC voltage on its output then that DC voltage is also amplified.
In such a case (a DC coupled amplifier) it is highly recommended to have DC protection on its output.
Such a protection usually kicks in when more than 0.5V DC is detected and disconnects the load (speaker or headphone)

2: When a source has a DC voltage on it and is connected to an amplifier that is not DC coupled then the DC does not matter that much.
It can cause a loud 'tick' when switching inputs or a 'thumb' when switching the source on when the amp is already active.

3: When the output of an amplifier is DC coupled, so no output capacitor, which is often the case with many amplifiers then, when something in the amplifier fails catastrophically there might come DC on its output (depends on the actual type of failure).
When such an amplifier does not have DC protection then it is possible DC appears on its output which potentially could destroy a woofer or headphone driver.
This is a design choice.
When an amplifier already has a start-up/or quick switch off relay in it (such as Schiit amps) then it baffles me something as simple as DC protection isn't implemented at all.
There are very chip IC's that have delayed-on/quick-off and DC protection in it that costs next to nothing. The relay is the most expensive part and is already in there.

Such a DC protection could save expensive drivers in case something goes wrong inside the amp.
Admittedly the chances are slim but for almost no extra costs an amplifier manufacturer can protect drivers from users of their amplifiers damage to their drivers. A design choice.

 

[xbb]

The Atom is not DC coupled from input to output so a DC on the input will not result in a DC output.

The manual states that the Atom is DC coupled and that the source should have a DC offset below 4 - 4.5mV

I'm waiting to receive mine yet. I'll be using it with a FiiO K3 until a I change it for something better.

I'm a bit worried because my FiiO K3 has about 4-5mV of DC offset in the right channel, could that be a problem?

 

[solderdude]

Indeed it is:

Atom Amp is DC coupled throughout. It’s been a long time since I encountered a source with DC offset. Consumer audio players are often AC coupled, and all JDS Labs DACs are DC coupled with insignificant DC offset.

4-5mV DC offset is not a problem given the output voltage of the signal.

This offset voltage passes through the volpot so in practice will be lower than the 4-5mV.

It becomes problematic when there is about 100mV or more DC offset. With this you can potentially kill sensitive headphone drivers.