Review and Measurements of New JDS Labs Atom Headphone Amp

[SirMaster]

Low gain.
Then set the volume to the maximum that you are gonna use instead of 100%.
If 100% at low gain is not enough then use high gain.

Well in a listening session I might listen to classical and jazz and then rock and EDM, so the dynamic range of the mastering can vary wildly.

I know about replaygain, but I have never really bothered to use that. Wonder if that would not be a bad idea either. But would replaygain boost the level of my really quiet classical music? Is a digital boost like that even safe from clipping or distortion?

Another reason for why I need higher volume than most is because I am using a Harman PEQ (oratory1990) for my HD800 which requires a -7.7dB preamp gain in order to prevent any frequency boosting/clipping

Occasionally even 100% low gain is not quite enough volume for my liking with some really quietly mastered tracks, but I think 100% low gain is enough for about 90% or more of my content at least.

But would you think that the downside of high gain would really be noticeable or is it likely a largely inaudible difference?

 

[JohnYang1997]

Well in a listening session I might listen to classical and jazz and then rock and EDM, so the dynamic range of the mastering can vary wildly.

I know about replaygain, but I have never really bothered to use that. Wonder if that would not be a bad idea either. But would replaygain boost the level of my really quiet classical music?

Another reason for why I need higher volume than most is because I am using a Harman PEQ (oratory1990) for my HD800 which requires a -7.7dB preamp in order to prevent any frequency booting.

Occasionally even 100% low gain is not quite enough volume for my liking with some really quietly mastered tracks, but I think 100% low gain is enough for about 90% of my content.

But would you think that the downside of high gain would really be noticeable or is it likely a largely inaudible difference?

Likely inaudible. Also as you control the incoming signal, the gain stage doesn't get saturated. Hence the distortion will be lower.

 

[SirMaster]

Great, thanks for all your info guys!

This amp really sounds amazing.

I decided to replace my old Woo Audio 7 with a SDAC / JDS Atom and I couldn't be happier with the results so far!

 

[MRC01]

... Another reason for why I need higher volume than most is because I am using a Harman PEQ (oratory1990) for my HD800 which requires a -7.7dB preamp gain in order to prevent any frequency boosting/clipping
...

That suggests the EQ is boosting some frequency range by 7.7 dB which is somewhat aggressive for the HD800. The only place the HD800 really needs a boost is in the low bass, and I find boosting it that much makes it sound bloated. There's another thread here discussing that over-EQing headphones can make the cure worse than the disease. You might try a gentler PEQ that doesn't require as much boost, which could give you a couple dB more volume.

A simple EQ that sounds good to me on the HD800 has 2 parts: -6 dB @ 6 kHz, Q=2.0 to reduce the treble resonance, and a bass lift (low shelf) starting at 80 Hz, +3 dB / octave (+3 @ 40 Hz, +6 @ 20 Hz). Then you'd only need -6 dB overall gain attenuation. In fact, -4 dB would be sufficient for music because it could only clip with a pure 20 Hz signal at 0 dB which would never occur in music.

 

[SirMaster]

That suggests the EQ is boosting some frequency range by 7.7 dB which is somewhat aggressive for the HD800. The only place the HD800 really needs a boost is in the low bass, and I find boosting it that much makes it sound bloated. There's another thread here discussing that over-EQing headphones can make the cure worse than the disease. You might try a gentler PEQ that doesn't require as much boost, which could give you a couple dB more volume.

A simple EQ that sounds good to me on the HD800 has 2 parts: -6 dB @ 6 kHz, Q=2.0 to reduce the treble resonance, and a bass lift (low shelf) starting at 80 Hz, +3 dB / octave (+3 @ 40 Hz, +6 @ 20 Hz). Then you'd only need -6 dB overall gain attenuation. In fact, -4 dB would be sufficient for music because it could only clip with a pure 20 Hz signal at 0 dB which would never occur in music.

You are correct it’s at the low end.

Here’s the EQ that I have been using:

https://www.dropbox.com/s/v999jbft39506ma/Sennheiser HD800.pdf?dl=0

It was actually measured by a guy using the same rig that was used by Sean Olive to create the Harman OE headphone curve in the first place and I have really been loving it. Of course the -8.2dB at 5800Hz is the biggest noticeable improvement.

I guess I like more bass because I have been enjoying this much noticeable bass boost. I wouldn’t call it bloated from what I’m hearing but of course different people can certainly have different interpretations.

Since the 7.7dB boost is way down around 20Hz perhaps I could raise my preamp gain a little already but I was just following the guide.

You think something like -5dB is safe for that curve?

 

[MRC01]

By "bloated" I mean slow & distorted, not just louder. With both headphones & speakers, when boosting bass with EQ, when I reach about +6 dB it starts to sound bloated, so that's the max I will use. I can adjust to bass that is leveled a few dB low, find it harder to adjust to bass that sounds bloated. At +6 dB you're forcing the driver to pump out 4 times as much power as it normally would. With single-driver headphones, the midrange and treble is riding as a ripple on the larger amplitude bass wave; this increased driver excursion forces the midrange and treble into the headphone's less linear range which can make it sound less crisp and coherent overall.

You can usually set replay gain 2 dB less than your biggest EQ boost, if that boost is not too wide a frequency range. This could allow clipping for a max level single-frequency test signal, but is safe with most music which consists of multiple frequencies. However, how safe it is depends on the music. Given that so much pop/rock is heavily dynamically compressed and pretty much always at max levels, this might not be safe for that genre.
PS: even with heavily compressed music, as long as it has a broad frequency spectrum the 2 dB rule won't clip.

 

[Deleted member 12179]

I got mine a week ago. I´m very happy with it. I have no experience with this kind of devices really, I can't compare with other amps. My only complain, I ordered JDS RCA cables, 10$, very cheap, but rca connectors are really really weak, they can come loose from the rca connector easily, they slide out like butter. The extra aux is a plus, I connected an Airport Express for airplay, that can stream to speakers too. It can drive my hd6xx 300ohms perfectly fine at low gain, always, saving your ears. For louder, high gain has plenty of power, although not sure how it would work with Fostex T50rp or similar... I don't mind the plastic for the price. Arrived in Europe extremely fast, 25€ taxes +14€ fees, from USA. So cheaper than from UK to here.

No complaints really. Maybe some people would prefer a switch so headphones can be always plugged, maybe direct pass through output to speakers when switched off with the volume knob so headphones could be always in? I guess each person would prefer a different thing, so no complaints really. Again, extra 3.5mm input is a plus for many.

 

[Irrenarzt]

The Ghent shorties aren't good grippers, but the OE shorties from JDS grip nice and tight. This scenario only applies for a stack where shorties are all you need. I have a KTB atop my Atom, so I only need the shorties.

 

[sotiridaf]

Hi all

i have the next headamp-pre amp

https://www.vincent-tac.de/en/product-lines/tubeline/khv-1.html

• Nominal Output Power RMS / 300 Ohm: 400 mWatt
• Nominal Output Power RMS / 32 Ohm: 1.75 Watt
• Harmonic Distortion: > 0.1 % (1 kHz, 100 mWatt)
• Input Sensitivity: 600 mV
• Signal-Noise Ratio: > 90 dB
• Input Impedance: 47 kOhm
• Output Voltage Pre Out: 2 V (max. 4 V)

if i buy Atom , i will have SQ better results with LCD2F?

Thanks!

 

[flipflop]

if i buy Atom , i will have SQ better results with LCD2F?

Nothing from these specs suggests the Atom would sound any different. The fact that they have omitted the output impedance is suspicious, though. Be cautious when using the amp with headphones that do not have a flat impedance curve like the LCD-2(F) has.

 

[JohnYang1997]

Nothing from these specs suggests the Atom would sound any different. The fact that they have omitted the output impedance is suspicious, though. Be cautious when using the amp with headphones that do not have a flat impedance curve like the LCD-2(F) has.

The harmonic distortion showed >0.1% which is odd.

 

[flipflop]

The harmonic distortion showed >0.1% which is odd.

Sure, but not something that would lead to the sound quality being impacted in any meaningful way.

 

[Veri]

Sure, but not something that would lead to the sound quality being impacted in any meaningful way.

I think JohnYang means, 'more than' 0.1% is weird lol

 

[flipflop]

I think JohnYang means, 'more than' 0.1% is weird lol

Oh, yeah, I think that must be a typo. Otherwise, they could have listed it as > 0.0001% and it would still be "correct". 0.1% is already pretty high.

 

[sotiridaf]

thank you for the replays...One concern of me is the tubes...Their performance decrease over time , correct?

 

[FrantzM]

Splitting hair, I see. The Atom will power 99.99% of the headphones on the market. Aside from Electrostatic headphones, from the top of my head, I can only think of 2 headphones that will be a tough challenge for it: the RAAL & the HifiMan HE6.
The Atom plays the HE6 to perhaps 80 ~82 dB comfortably. You can tell it won’t go higher though.

 

[solderdude]

The HE6 (and K1000) will reach 107dB SPL peak on Atom so around 90dB average.
It cannot power the SR1A at all.

 

[solderdude]

thank you for the replays...One concern of me is the tubes...Their performance decrease over time , correct?

Yes, impossible to tell when a tube goes bad. One has to see tubes as consumables. Besides... most folks will start to roll tubes and often and up with tubes that aren't even suited but exhibit an effect they like.

 

[solderdude]

if i buy Atom , i will have SQ better results with LCD2F?

I don't thinks so... the measurements of the Atom will be better but the experience with the amp you already own will probably be more satisfying.

 

[sotiridaf]

I don't thinks so... the measurements of the Atom will be better but the experience with the amp you already own will probably be more satisfying.

I agree , since i am satisfied , to buy another amp just because is very good is the illness of buying