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Review and Measurements of New JDS Labs Atom Headphone Amp

PierreV

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+1 for testing randomly sampled released stuff shipped to customers. While I don't suspect any kind of foul play, this approach would be cleaner in principle. But, yes, of course I will get one :)

secondary question: when the perfect cheap amp, perfect cheap dac have been found, what's the point of testing others?
And what will I read on my breaks? Transparent, airy, agile, punchy, discerning cable reviews for a good laugh?
 

Timbo2

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Exceptional performance for an excellent pricepoint!

I wonder how it would pair with an excellent sub US$100/- DAC though ? Was thinking hooking it up with a Sabaj Da3 and use its balanced 2.5mm output to the Atom's RCA inputs.

It would make for a really nice budget headphone setup, thats actually very much "transportable" between home and office for example.

@amirm , would it be possible to test such a setup ? ( if you still have the Sabaj Da3). Or plug a D50 into this !
I don’t think the Sabaj takes kindly to having a common ground for its balanced mode, but I’m not sure.
 

Veri

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JDS labs sure outdone themselves on this thing wow.

I wonder if they will be able to be custom engraved! :D
 

Silou

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Would be cool if someone could post a link to the atom once it is officially released.
 

Bamboszek

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Could we also get a pic under the hood too:)? Both Magni 3 and Liquid Spark use discrete designs, curious to see if JDS Labs went for the same route as well.
I suspect they might be using recently released TI opamp especially designed to drive headphones - OPA1622. Maybe few in parallel to increase power.
 

March Audio

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i'm new to this but this atom seems like a no brainer for someone looking to get into higher fidelity . will the plastic case cause any issues ? i'm from the school of thought that metal provides shielding from RF and such that could become audible and/or cause noise issues . is that something that doesn't have to be considered these days or with this particular unit ?
RF is still an issue and should be considered, directly on the input connections and through casework. Metal case will perform better for shielding however it should be stressed that the end result, how sensitive the unit is to RF, will depend on many circuit variables and it really is not necessarily true that this unit would have any I'll effects due to a plastic case under normal conditions. Ie not living next to an AM transmitter.
 

bunkbail

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I suspect they might be using recently released TI opamp especially designed to drive headphones - OPA1622. Maybe few in parallel to increase power.
I doubt that. I haven't seen anybody uses precision opamps from TI (the SoundPlus ones) to directly drive headphones. I couldn't find any design that has them even with the slightly older OPA1612, at least in this price bracket.
 

Bamboszek

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Well, most of opamps are not suitable to drive headphones direcly without some sort of buffer like discrete transistor or LME49600. They don't offer adequate current and distortion rises at low impedance loads. OPA1622 is slighty diffrent as it is especially designed for this role and has over 130mA Iout. I also didn't seen any commercial designs using OPA1622 but it is pretty fresh part. There are few projects at diyaudio. Check this or this thread for more info.
 

trl

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[...]
Since some of you have been asking, I also added the phase information. As we see, the differential of 0.003 degree means there is nothing there to worry about.
[...]

Thank you, Sir! :)
Would you mind, please, instead of testing 1 KHz sines to try 10 or 15 KHz sines phase tests, please (at least for future amps)? Usually at 1 KHz things are perfect on most amps. People complains about bass roll-off or trebles sounding too upfront or in-your-face etc., so wondering if phase-shift/delay might have something to do with that or not.

Are you allowed to take internal pics on the Atom? I was wondering what's on the output buffer. Given the >1W output power, I'm not sure they kept the same 2 x NJM4556.

Thank you,
Raul.
 

Veri

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Are you allowed to take internal pics on the Atom? I was wondering what's on the output buffer. Given the >1W output power, I'm not sure they kept the same 2 x NJM4556.

I think amir was hesitant to take pics of the hardware before even the official release :) possibly later?
 
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trl

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trl

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I think amir was hesitant to take pics of the hardware before even the official release :) possibly later?
I'm sure about that, also...I don't think there are screws, so outer case might get a bit damaged if open/close for many times. I'm optimist that JDS and Amir for this Christmas will show us some great inside pics of this headamp; also, I'm pretty sure it's >99% O2 inside, but looking further to see. :)
 

trl

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March Audio

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I couldn't find this graph on Amir's Benchmark DAC1 test page, perhaps I'm missing something, sorry, but what device has these fantastic measurements, please?
My headphone amp. Amir has measured the prototype, a full review has not been performed yet.

I had a senior moment and labelled the graph dac 1 instead of HPA1 :)
 

March Audio

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Sorry for the Off-Topic, but found it here: https://www.audiosciencereview.com/forum/index.php?threads/march-audio-hpa1.4430/post-114826:)
I'm really waiting for inside pics on HPA1 and DAC1 and complete measurements for both units too (also the pricing, ofc). Congrats!
Amir has one of the first batch of dac1 units arriving this week. The first batch had a problem with the text printing on the case so are not on general sale. Revised version in manufacture at the moment, so a couple of weeks away.

The headphone amp has unfortunately been put to the the back of the list, the range of power amps will be first in about 3 weeks.
 

Veri

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The headphone amp has unfortunately been put to the the back of the list, the range of power amps will be first in about 3 weeks.

Any particular reason :)?

BTW, if there is any kind of revision– would you consider an XLR out on the amp? Doesn't need to be balanced, just for convenience. I'm sure there's other neurotics that would appreciate XLR pin-out, even as a more expensive add-on option.
 

bakker_be

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Just when I ordered the DX3 Pro (150€), when all I actually "needed" was an amp ...
 
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