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Geshelli Archel Pro v/s JDS Atom v/s .....

Noob

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#21
The only thing that gives me pause about the Atom is some of the channel imbalance issues that have been spoken of. Though since you're (I assume) maxing the volume on it, this isn't an issue it might turn out to be.

If power is what you lack, and you want to stick to budget, the Magni 3 seems a close contender.
I would say the magni 3 barely powers r70x headphones to acceptable levels. It will be listenable, but it won't be very loud, and it won't be driven properly. Maybe a higher input signal could fix that, but I have not had a great experience using the magni 3 with the r70x.
 

Anubhav

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#22
I would say the magni 3 barely powers r70x headphones to acceptable levels. It will be listenable, but it won't be very loud, and it won't be driven properly. Maybe a higher input signal could fix that, but I have not had a great experience using the magni 3 with the r70x.
That's the very reason i started this thread. Coz i feel that Geshelli is a better setup than JDS Atom.
But am i doing it correctly ? May be not, hence the request to measure and compare both properly
 
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#23
I own the enog2 pro, Archel pro and atom. The Archel puts out way more power and works best with higher impendance headphones. I can max out the atom while watching movies but music is fine. I find the atom to be much cleaner sounding! But I feel more of an emotional connection to my music through the Archel. I should not both Geshelli products are being run through my linear bench top power supply (bass is substantially improved and less harshness on the top end). Even with this the atom still sounds cleaner. They are pretty close otherwise. I should note I've always had the smallest amount of channel imbalance at the very beginning of the volume knob on the Archel but not on the atom. Not enough to ever both me but it is there.
 

Tks

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#24
I would say the magni 3 barely powers r70x headphones to acceptable levels. It will be listenable, but it won't be very loud, and it won't be driven properly. Maybe a higher input signal could fix that, but I have not had a great experience using the magni 3 with the r70x.
High gain + Max volume barely enough to power it o_O my goodness, had no idea an extra 170 ohms would chew through power like that. By that metric, avoid the Atom then for sure. But then again I listen to music at quite low levels compared to most folks (even when I wass a kid I had this sort of OCD of avoiding hearing damage as much I can, it was ingrained into me while seeing people on the subways with volume so loud on their listening devices, I could hear the song fully playing 2 meters away on top of all the noise of a train cart).
 

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#25
High gain + Max volume barely enough to power it o_O my goodness, had no idea an extra 170 ohms would chew through power like that. By that metric, avoid the Atom then for sure. But then again I listen to music at quite low levels compared to most folks (even when I wass a kid I had this sort of OCD of avoiding hearing damage as much I can, it was ingrained into me while seeing people on the subways with volume so loud on their listening devices, I could hear the song fully playing 2 meters away on top of all the noise of a train cart).
The ohm rating on the R70x is measured at 1k instead of averaged. It has an impedance peak over 900ohms that brings the average higher than one might assume. The sensitivity is also a few dB lower than most high impedance headphones.
 

maxxevv

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#26
High gain + Max volume barely enough to power it o_O my goodness, had no idea an extra 170 ohms would chew through power like that. By that metric, avoid the Atom then for sure. But then again I listen to music at quite low levels compared to most folks (even when I wass a kid I had this sort of OCD of avoiding hearing damage as much I can, it was ingrained into me while seeing people on the subways with volume so loud on their listening devices, I could hear the song fully playing 2 meters away on top of all the noise of a train cart).
Its mostly a sensitivity issue rather than the impedance values. The R70X reads 98db and the HD800 reads 102 dB/1V rms , HD6xx/650 reads 112 dB/ 1V rms
The specific value of the R70x isn't specified but if similar then it needs a fair bit more power than the HD800 and far more than the HD650/6XX.

I have run the HD800 ( which has a similar transient impedance peak to the R70X at about 2.2x its rated impedance) with the Atom and there was more than enough volume by the time my volume knob at 3 o'clock position I have to turn it back a bit. So too the HD6XX, but that stops at 12 at the very most 1 O'clock for the volume pot.

And the Atom was connected via a Khadas Tone Board.
 

Tks

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#27
Its mostly a sensitivity issue rather than the impedance values. The R70X reads 98db and the HD800 reads 102 dB/1V rms , HD6xx/650 reads 112 dB/ 1V rms
The specific value of the R70x isn't specified but if similar then it needs a fair bit more power than the HD800 and far more than the HD650/6XX.

I have run the HD800 ( which has a similar transient impedance peak to the R70X at about 2.2x its rated impedance) with the Atom and there was more than enough volume by the time my volume knob at 3 o'clock position I have to turn it back a bit. So too the HD6XX, but that stops at 12 at the very most 1 O'clock for the volume pot.

And the Atom was connected via a Khadas Tone Board.
Ahhh I totally forgot about the sensitivity spec! Sorry sorry, it makes more sense why the fellow might want more power now!
 
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#28
I also have an archel pro, it's not bad even compare to thx 789 single end.
 
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spronkey

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#29
Got a phone? Install a decent dB meter app, Attach the microphone end a repeatable position on your headphones inside the earcup, play some pink noise, and find the level on each amp that matches.

I've found this can get acceptably accurate for comparing amps. Not so much for comparing between headphones though.
 
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#30
I've heard the Archel and Atom side-by-side as well and also preferred the Archel. As popular as the Atom is here, I'm going to go against the grain and say that it left me unimpressed. The Atom sounds boring and dull, while the Archel is punchy and exciting.

My one complaint with the Archel is that it is TOO powerful at its stock gain, and that while it sounded spectacular with my Audeze LCD2 it did distort at high volume with my Aeon Flow Closed (a very low impedence headphone and very picky with amp pairings). If you email Geshelli they will build one with lower gain. IIRC the stock gain is 6x; I had one ordered with 2x and I think even this is a little high with a 2v source. I bet 1.5x would be perfect.

Amir, I would love to see the Archel measured!
 

GGroch

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#31
....The Atom sounds boring and dull, while the Archel is punchy and exciting...
Amir, I would love to see the Archel measured!
I would like to see it measured too. But, if the Archel actually sounds significantly different from the Atom, then it certainly will not measure well.

Amir's measurements show the Atom to be transparent. That is, the signal that comes out is acoustically identical to the signal that goes in...but amplified. So if you are actually hearing a difference, then the Archel Pro must be modifying the sound to something that you find punchy and exciting, but is not transparent.

Nothing wrong with that, I like the sound of my LIttle Dot MKiii tube amp. But, I do not expect it measures well, or is accurate. If my LDMKiii DID measure close to the Atom in accuracy, that would prove the warm musical sound I hear is 100% my expectation bias.
 
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amirm

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#32
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#33
Hi guys! I was all set to buy an Atom but now I see this and I feel a little bit rocked. Does it come down to a personal preference of sound between these two?
 
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#34
Hi guys! I was all set to buy an Atom but now I see this and I feel a little bit rocked. Does it come down to a personal preference of sound between these two?
It comes down to what headphones you are trying to drive. Higher impedance headphones, 300 ohm and up, will work better with the Archel Pro. Lower impedance headphones will benefit from the lower noise floor of the Atom. It depends on the headphone.
 

GGroch

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#35
It comes down to what headphones you are trying to drive. Higher impedance headphones, 300 ohm and up, will work better with the Archel Pro....
I would really like to see either measurements of the Archel or at least specifications from Geshelli on what output can be expected at 300 ohms. The Geshelli website only mentions 1W output at 16 ohms. The Atom measured higher than that at 32 Ohms. It is very hard to subjectively compare real output when both the low & high gain on the Atom are far lower than the fixed gain of the Archel. Has Geshelli published any output specs at higher impedances?
 

solderdude

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#36
@Noob What typenumber is on the small DCDC converter (the black square). This will give us a clue of the voltage rails used and the expected max output voltage and which opamps are used ?

EDIT:
It is a 2W +/-15V power supply which is equal to that of the Atom.
so one can expect about the same max output voltage levels with loads above 100 Ohm.


My hunch is that the Geshelli has a higher gain or different taper and is subjectively preferred because of level differences.
The sound difference descriptions perfectly match that of a somewhat 'louder' signal.
 
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Veri

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#37
My hunch is that the Geshelli has a higher gain or different taper and is subjectively preferred because of level differences.
The sound difference descriptions perfectly match that of a somewhat 'louder' signal.
Quite likely. It is a really loud amp. I recently asked about gain config in their amp and if they would send one to amir, this is what they replied:

The default gain is 5-6x. Yes, you can request custom gain settings. We have quite a few customers who change their gain depending on their setup and headphones. There is no charge for changing the settings, you would only pay shipping.

We are working on a new amp that we're hoping to release at the end of the year. ASR will receive the new version.

Thank you for your interest in our products.

Sherri
Geshelli Labs LLC
 

GGroch

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#38
The Geshelli website says it has a linear taper potentiometer, so that plus the a 6x gain (or 5, 6 is the figure I see quoted on other sites) would produce a much high percentage of its output at lower levels than the Atom which has 1x/4.5x switchable gain and a 15A audio taper.
 

solderdude

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#39
The picture in the OP confirms the linear taper (B 100k marking).
This explains the difference in volpot settings.
It is possible (but unlikely) the linear pot is in the feedback path of an inverting amp which would make the response closer to log type.

That would make the Geshelli less suited for low impedance headphones with such a high gain and almost no usable volpot range down below and indeed more suited to drive higher impedance headphones.
 
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debunker

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#40
My hunch is that the Geshelli has a higher gain or different taper and is subjectively preferred because of level differences.
The sound difference descriptions perfectly match that of a somewhat 'louder' signal.
I have the same hunch. Also, it's interesting to hear people use descriptors like "punchy", "exciting" and "meaty". When I read that I think, "distortion". The stated THD on the Geshelli site is 0.01%. That is more than an order of magnitude higher than the Atom and means that distortion is 80 dB below the signal. That might be hitting a sweet spot where it's not quite registering as distortion to the listener but is giving the impression that the sound is more impactful than a truly transparent amp like the atom.

I would really like to see either measurements of the Archel or at least specifications from Geshelli on what output can be expected at 300 ohms. The Geshelli website only mentions 1W output at 16 ohms. The Atom measured higher than that at 32 Ohms. It is very hard to subjectively compare real output when both the low & high gain on the Atom are far lower than the fixed gain of the Archel. Has Geshelli published any output specs at higher impedances?
Some hand-wavy math. At lower impedances, the amp will hit some maximum current level, and the voltage and wattage will be correspondingly limited. At higher impedances current is no longer the limiting factor and it becomes voltage limited up to the maximum that the given op amp can handle at a given rails voltage, which in the case of the Atom is 8.68V rms at 600 Ohm. The Archel uses an LMH6321 for the output buffer which for a 1kOhm load has a peak output voltage of +/- 13.4 Vpp for a +/- 15V supply, which translates to 9.47V rms. So even if hypothetically the Archel could still output that voltage with a 600 Ohm load, we're looking at 150mW for the Archel vs 125mW for the Atom. Which translates into what, an extra half dB or so in real terms? It really shouldn't make any difference.

ATOM sounds right for low impedance headphones. But for ATH R70x (470ohms & 98 decibels) or other demanding headphones, it's getting dicey.
This is not my experience at all, and I suspect it again goes back to the linear vs audio taper of the volume pot. My main headphones are 600Ohm Beyer DT-880 and the Atom has always been plenty loud for my needs. For most listening I keep the volume between 11-12 o'clock in low gain mode, higher if it's classical or jazz or older pre-loudness wars rock, and I only use high gain mode if I'm doing some precision editing work on my own un-mastered recordings. The DT-880s are lower sensitivity (96dB) than the ATH-R70s, so even with the latter's impedance bump I would have thought it would be fine.
 

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