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JDS Atom Amp 2 Headphone Amplifier Review
- Thread starter amirm
- Start date
This proves one thing: discrete headphone amps are dead.
The Atom Amp 2 uses 8 dual OPA1656 op-amps in parallel, paralleled through 1 Ω resistors. You can literally trace the layout through photos you can Google in no time - it’s that simple. No magic. Just paralleled op-amps. Opening the OPA1656 datasheet reveals harmonics under -160 dB (!!!) into 2 kΩ. Parallel enough of them to deliver the desired current, and you’re golden.
Even the power supply is laughably simple: a voltage doubler rectifier from a single AC wall adapter. In the past only cheap/basic head-amps did it this way. This is why you see a 60 Hz mains hum on the spectra but no 120 Hz - each rail only receives half of the sine wave - followed by jellybean LM317/LM337 regulators bootstrapped in D-Noizator diyaudio.com fashion. And then designers rely on high PSRR of 1656.
And this concept isn’t new. Douglas Self did the same thing in 2010 with 32 pieces of NE5532 to deliver 16 W into 4 Ω speakers, achieving 0.0005% THD at 1 W.
The Atom Amp 2 uses 8 dual OPA1656 op-amps in parallel, paralleled through 1 Ω resistors. You can literally trace the layout through photos you can Google in no time - it’s that simple. No magic. Just paralleled op-amps. Opening the OPA1656 datasheet reveals harmonics under -160 dB (!!!) into 2 kΩ. Parallel enough of them to deliver the desired current, and you’re golden.
Even the power supply is laughably simple: a voltage doubler rectifier from a single AC wall adapter. In the past only cheap/basic head-amps did it this way. This is why you see a 60 Hz mains hum on the spectra but no 120 Hz - each rail only receives half of the sine wave - followed by jellybean LM317/LM337 regulators bootstrapped in D-Noizator diyaudio.com fashion. And then designers rely on high PSRR of 1656.
And this concept isn’t new. Douglas Self did the same thing in 2010 with 32 pieces of NE5532 to deliver 16 W into 4 Ω speakers, achieving 0.0005% THD at 1 W.
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Bernard23
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OK, but who is checking the data sheets?
I can say for the price it's neutral but natural sounding. It drives my Sennheiser HD598 much better than my Schiit Modi/Magni 3+. It sounded a bit muddy there at times and I think it's due to the lack of current to handle the 300ohm drop around 80hz. The JDS doesn't bat an eye. It's basic, but surprisingly good looking and seems to be rock solid reliable.
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That's not true.
The only thing you can hear is your headphones. Output impedance is less than 1 Ω - this amp is not dependable on the driven headphones in any meaningful way and its measured parameters are at the edge of measurement equipment and on many orders of magnitude way beyond our hearing. If the cans are muddy, they are muddy, it's not the amp. If they sound better with something else - it's a strong placebo.
And with higher impedance it's not about the higher current, but higher voltage swing to deliver the same power. This amp has both, voltage and current, to literally pop, smoke and burn any dynamic headphones in 8 - 600 Ohm range at high gain. Heck it could possibly drive large speakers to a listenable level, LOL. You can get few watts into 4-8 Ohms, each of 8 op-amps can deliver 100 mA.
The only thing you can hear is your headphones. Output impedance is less than 1 Ω - this amp is not dependable on the driven headphones in any meaningful way and its measured parameters are at the edge of measurement equipment and on many orders of magnitude way beyond our hearing. If the cans are muddy, they are muddy, it's not the amp. If they sound better with something else - it's a strong placebo.
And with higher impedance it's not about the higher current, but higher voltage swing to deliver the same power. This amp has both, voltage and current, to literally pop, smoke and burn any dynamic headphones in 8 - 600 Ohm range at high gain. Heck it could possibly drive large speakers to a listenable level, LOL. You can get few watts into 4-8 Ohms, each of 8 op-amps can deliver 100 mA.
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You didn't follow what I posted. My headphones sounded muddy on the Schiit Magni but not the JDS Labs Atom2.
I'm very sorry, I've got you wrong. It was late.
Still, both are very low distortion and impedance devices. Magni 3+ is a classic Diamond buffer inside op-amp feedback loop, age old design, it can't get near modern op-amps, yet it can provide insane amounts of current in headphones terms. Both high and low impedance drive should be extremely easy for it.
Btw, Schiit offers Heresy amp and a funny thing it's exact same topology as Atom Amp 2: 8 OPA1656 op-amps in parallel through 1 Ohm resistors and LM317/LM337 basic regs.
Still, both are very low distortion and impedance devices. Magni 3+ is a classic Diamond buffer inside op-amp feedback loop, age old design, it can't get near modern op-amps, yet it can provide insane amounts of current in headphones terms. Both high and low impedance drive should be extremely easy for it.
Btw, Schiit offers Heresy amp and a funny thing it's exact same topology as Atom Amp 2: 8 OPA1656 op-amps in parallel through 1 Ohm resistors and LM317/LM337 basic regs.
Yeah I thought about trying to buy one of the Heresy amps but decided I'd rather move up the line instead. Considering a Mjolnir 3 currently.
Jimster480
Major Contributor
Don't worry about it, moving up doesn't get you better sound quality. The Atom is SOTA already, you won't find better sound quality unless you have a specific type of headphone that needs something the Atom cannot do.
I'm actually looking for a colored amp this time, so might end up with tubes or something.
Jimster480
Major Contributor
Why would you want something colored? If you want to play with the sound; just get an amp with Tone controls like the Geshelli Archel 3 Pro.
OldFunkyBones
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Or just add the Atom Phono preamp to the stack and use the tone control mode?
Atom Phono _ Shop JDS LABS
Atom Phono is a strong RIAA phono preamp and clean tone control all in one. Its flexible bypass toggles let you use it as an equalizer or a phono preamp, or both, or neither. Selectable 30/40 dB gain delivers far more volume than typical, integrated phono preamps, while maintaining impressively...
jdslabs.com
I actually have considered this. I also have. Wiim for PEQ.Or just add the Atom Phono preamp to the stack and use the tone control mode?
Atom Phono _ Shop JDS LABS
Atom Phono is a strong RIAA phono preamp and clean tone control all in one. Its flexible bypass toggles let you use it as an equalizer or a phono preamp, or both, or neither. Selectable 30/40 dB gain delivers far more volume than typical, integrated phono preamps, while maintaining impressively...
I'm all in on JDS Labs. Got an Element 4 at my desk, this replaced the Schiit Modi/Magni 3+ stack. Was a pretty huge upgrade. In my bedroom is a JDS Atom 2 stack. Sounds fantastic. Neutral but natural.
Jimster480
Major Contributor
Definitely amazing value, powers basically everything and its neutral. Just add a tone control box of some kind since they exist. I personally enjoy the tone controls on my Geshelli Archel3 Pro; it has RCA output too and can apply the tone controls on that; so I can connect my Archel 2 Pro (like the Atom) and drive multiple headphones at the same time using the tone controls.
I actually have looked at the Archel 3 Pro several times. Getting it in Walnut would match my BMR Towers. I'm curious about the power though and if they could run harder to drive headphones?
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