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JDS Labs ATOM AMP vs. ELEMENT AMP II

Michael YYZ

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I am hoping someone could please help me decide between these two great devices.

Based on the published specs, both the ATOM AMP and the ELEMENT AMP II have an output impedance of 0.1 Ohms, although the latter is more powerful (9.9 Vrms vs. 8.66 Vrms, into 150 Ohms). However, Amir measured higher output impedance values of 0.7 (https://www.audiosciencereview.com/...ents-of-new-jds-labs-atom-headphone-amp.5262/) and 1.2 Ohms (https://www.audiosciencereview.com/...lement-ii-dac-and-headphone-amp-review.10029/), respectively.

I would be using the amp mostly with my Sennheiser HD650 headphones (300 Ohms) and occasionally with my Shure SE846 earphones (9 Ohms and 5 Ohms min.). Based on the 8x rule of thumb and the ASR measured values, the ELEMENT AMP II would not be suitable for the Shure earphones, while the ATOM would be marginally okay. What is your opinion on this? Also, other than the increased power and looks, what would be the advantage for the ELEMENT AMP II vs. the ATOM, to justify the 2.5x price difference?

Thanks!
 
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AudioStudies

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You seem to be comparing a stand alone amp (atom) with a combination dac/amp (element II). If it is an amp you need, the comparison for JDS Labs products would be the Atom with El Amp II (amp only). I have the El Amp II and love it. Only slightly more power than the Atom, but better parts quality, although the circuit is the same in both. I love the metal casing of the El Amp II (Atom has plastic), and I love the over-sized volume knob. Only caveat I have about the El Amp II is that switching between low gain and high gain is done on the back of the unit, and it is sometimes difficult to tell which mode your in.
 
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Michael YYZ

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Thanks!

Well, I meant the amp section only, not the DAC. I edited my original post.

I am somewhat puzzled by the difference between the specs and the measured values, but more between the two different output impedances measured by Amir for the two devices, when my understanding is that both devices use the same LME49600 chips. It should not matter for the HD650, but I am concerned about the SE846. Thoughts?...

You seem to be comparing a stand alone amp (atom) with a combination dac/amp (element II). If it is an amp you need, the comparison for JDS Labs products would be the Atom with El Amp II (amp only). I have the El Amp II and love it. Only slightly more power than the Atom, but better parts quality, although the circuit is the same in both. I love the metal casing of the El Amp II (Atom has plastic), and I love the over-sized volume knob. Only caveat I have about the El Amp II is that switching between low gain and high gain is done on the back of the unit, and it is sometimes difficult to tell which mode your in.
 

AudioStudies

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I am concerned about the SE846. Thoughts?...
Sorry, I don't own the SE846 or know much about it. I do have the clone of the 650, the HD-6xx. The same chip in the same circuit, but perhaps some of the upgraded parts in El Amp is the cause of the impedance difference? I wonder if JDS Labs has a return policy, and if it can't drive your SE846 properly, then you could return. Everything I have heard, JDS Labs is a great company, including their technical support. They may have an opinion on whether their amps could drive the SE846.
 
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Bob-23

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I am somewhat puzzled by the difference between the specs and the measured values, but more between the two different output impedances measured by Amir for the two devices, when my understanding is that both devices use the same LME49600 chips.
Output impedance is mainly determined by an output resistor, and to a much lesser degree by wiring resistance; the chip's output resistance itself is zero - so we have to suppose that in both of the amps there is no output resistor, and the difference between the official specs and Amir's measurements are caused by different wirings resp. the additional wiring when measuring. Such low resistances are very hard to measure because the resistance of the (wiring of the) measuring device itself comes into play. For your shure it shouldn't matter which amp you use.
 
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Jimbob54

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The more important question for your Shure is how sensitive are they. On my more sensitive IEMs I get noticeable background hiss from the Atom. I would guess the same for the EL amp and indeed most amps.

I hate full size amps for that reason with IEMs so tend not to use. Personally, id use a dongle DAC/ amp for IEMs - far better suited.

EDIT- the Shure 846 are 114dB /mw- very sensitve. My guess is that you would get hiss
 
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Michael YYZ

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Bob, you make a very good point about the resistance of the measuring leads, although if the two amps have identical output stages - i.e. no output resistor on pin 4 of the LME49600 - why did Amir report different values for them, assuming that the measurements were consistent in each case?

Output impedance is mainly determined by an output resistor, and to a much lesser degree by wiring resistance; the chip's output resistance itself is zero - so we have to suppose that in both of the amps there is no output resistor, and the difference between the official specs and Amir's measurements are caused by different wirings resp. the additional wiring when measuring. Such low resistances are very hard to measure because the resistance of the (wiring of the) measuring device itself comes into play. For your shure it shouldn't matter which amp you use.
 

Jimbob54

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Bob, you make a very good point about the resistance of the measuring leads, although if the two amps have identical output stages - i.e. no output resistor on pin 4 of the LME49600 - why did Amir report different values for them, assuming that the measurements were consistent in each case?

I think you are somewhat overplaying the importance of (very low) output impedance on your IEMs and also the importance of a reported 1/2 ohm difference in two different amps when measured at different times. See my post above about what should concern you for using the amps with your Shure.
 
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Michael YYZ

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You are correct about the sensitivity value for the SE846.

Why would you hear a hissing noise from the Atom on sensitive IEMs? Is that amplifier noise, or noise from the source?

I have mostly been using the SE846 with an EarStudio ES100, which has a stated output impedance of 0.5-1 Ohm (probably depending on the output type: balanced vs. single ended), and did not notice any hiss coming out of them.

The more important question for your Shure is how sensitive are they. On my more sensitive IEMs I get noticeable background hiss from the Atom. I would guess the same for the EL amp and indeed most amps.

I hate full size amps for that reason with IEMs so tend not to use. Personally, id use a dongle DAC/ amp for IEMs - far better suited.

EDIT- the Shure 846 are 114dB /mw- very sensitve. My guess is that you would get hiss
 
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Michael YYZ

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Well, the 9 Ohm impedance for the SE846 was measured as 10 Ohm at 1 kHz, but it varies from 16 Ohms below 100 Hz to 5 Ohms at 5 kHz. That’s a factor of three! So, in theory, the frequency response of these IEMs ought to be sensitive to the output impedance of the amplifier.

I did read your previous post.

I think you are somewhat overplaying the importance of (very low) output impedance on your IEMs and also the importance of a reported 1/2 ohm difference in two different amps when measured at different times. See my post above about what should concern you for using the amps with your Shure.
 

Jimbob54

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Well, the 9 Ohm impedance for the SE846 was measured as 10 Ohm at 1 kHz, but it varies from 16 Ohms below 100 Hz to 5 Ohms at 5 kHz. That’s a factor of three! So, in theory, the frequency response of these IEMs ought to be sensitive to the output impedance of the amplifier.

I did read your previous post.
I was really hoping someone who can explain it properly would step in here. But I'll give it a go.

All amps have a noise floor. Plug transducers in and it is there to be heard. The audibility of that noise depends on the level of the noise itself (noise to signal) and the sensitivity of the transducer to the signal coming out of the amp.



The noise sits underneath any actual intended signal, the higher the signal is amplified, the less obvious the noise is.

The Shure are very sensitive so "hear" the noise at no signal volume. Because they are sensitive you can't turn the volume up much before too loud. So you have a higher signal to noise ratio. Ie you hear the noise between tracks and in quiet passages.

The Atom is by no means a noisy amp, but I suggest with the Shure you will hear it.

Also, see channel imbalance at low volume.

Other members, feel free to teach me exactly where I'm wrong
 

Bob-23

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why did Amir report different values for them, assuming that the measurements were consistent in each case?
In addition to what has been said: He might simply have had a slightly different set-up, other cables, other connectors...These low resistances are hard to measure, there's a lot of 'noise'. And determining output impedance isn't a simple measuring, it can't be done directly, implies some calculations, hard to do with absolute accuracy.
 

LTyla

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@Michael YYZ I'd be curious to hear on what did you end up going with amp/dac wise? And what's your experience?
I'm also thinking of upgrading my Asrock z97 Extreme4 onboard (it's no slouch, especially power wise) or Macbook Pro audio to go with HD6xx and Moondrop Blessing 2.

I'm leaning towards an all in one solution like Element 2 or Topping DX3 Pro+ (which I have already ordered, but did cancel after finding out that the seller doesn't even know when they are gonna get it re-stocked and reading several complaints of the initial buyers).

After many hours of research it looks like it's nearly impossible to have a one device to power both fairly hungry headphones and sensitive IEMs or am I missing some sort of a gem device? :)
 
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