Massdrop Objective 2 Headphone Amp: Desktop Editionsearch
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Massdrop Objective 2 Headphone Amp: Desktop Edition

Massdrop Objective 2 Headphone Amp: Desktop Edition

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(120 reviews)
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What is the current VAC of the 110 V AC Adapter being shipped with the O2?
Hi, I have a yamaha mg10xu mixer, with an already amped output, but it doesn’t have enough power to drive 600ohm cans. Can I hook up an amp to the already amped source, or will it affect the sound, if so, how much. I don’t have much experience with ”high power” amps . If you need more details, tell me. Ty!
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Kinda new around here but, wanted to know how do they drive the Sennheiser HD 660s's
AmazonPrime
Drives them very easily, barely have to turn up the volume on low gain.
Hey guys is this amp still relevant after being up for so long in terms of price vs performance? Is this the right time to get it? Im just confused and totally paralysed when there are so many options if its not sold on massdrop.
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I use the O2 because I can power it without AC mains power for when I am in transit and I use it on AC power at work. At home I have the Massdrop THX AAA 789. I've yet to find a battery powered amplifier that performs better than the O2 in hybrid desktop / portable use. The ability to output 4.5V on battery and 7V on mains power is nice to have.
(Edited)
How does the JDS Labs Atom compare to the Magni 3? I pretty much know nothing, and want to spend my money wisely.
Can this be used without a DAC. Like, can I just run a 3.5mm to rca from my phone/mp3 player to this and just use it as a stand alone amp?
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Solderboy23
Of course it can. I use it connected to the analogue outs of my standard amp at home or (a second, portable unit) connected via 3.5mm jacks to my portable player on the road.
Solderboy23
you can but you will be double amping the signal coming out of your phone's 3.5, which is already amped. This will result in dirtier sound no matter what you do, make sure when you do stuff like that your phone is on max volume. I still implore you to buy a dac, even a 30 dollar d03 would be better than double amping out of your phone.
Heads up, the JDS Labs Atom released. They consider it to be the successor to the Objective 2 (this model on Massdrop). It’s also about $99 and has better specs- cleaner power, more power, same outputs with an additional RCA out to use as a switchable preamp too, it bests Massdrop’s THX AAA 789 SNR, and to Massdrop Product Management - GET ON THIS NOW. Product: https://www.jdslabs.com/mobile/products/190/atom-amp/ Amir’s review and measurements: https://www.audiosciencereview.com/forum/index.php?threads/review-and-measurements-of-new-jds-labs-atom-headphone-amp.5262/


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SINAD of 114db and SNR of 124db. ”Yes, this is Massdrop THX AAA 789 territory. And no, the Atom does not use THX technology.”
Artismo
Worse SINAD though. But for the price difference, who cares. SNR is a bit misleading, the Magni 3 looks close, but when you look at SINAD, the Magni 3 drops to 97, whereas the 789 and the Atom are at 116 and 114 respectively.
Artismo
I thought the 789 had a ridiculous SnR of like 143 boy was I mistaken
I am more than likely going to buy the sennheiser 6xx headphones and from what I am told I need to get a DAC or amp thing to make them work the best. What would be best for $100 or less
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Hey do you know much about this product NuForce uDAC-5 DAC/Amp Combo? It just dropped and is about the same price as the atom amp, I really don’t know much about amps and dacs. Would I just need the jds atom amp or should I get the nuforce combo.

Notanaudiophile
You’ll need a DAC with the Atom, and I recommend a Topping D30 for a clean signal and transparency. It’s similarly priced and double the cost total (amp and DAC) to the Nuforce. The HD6XX is basically a 650, 300ohm impedance and sensitivity at 103db. The Nuforce puts out 140mW at 32ohm, meaning powering the 6XX it will be significantly less. I didn’t find any reviews or specs under a 300ohm load, but being USB powered only, I imagine it being a bit anemic. I would suggest, for listening pleasure and to truly hear your Senn sing, cleaner and more power.
Hello all. I recently bought this amp but when i turn it on there is a popping noise that is heard on the headphones. I tried different headphones and I get the same issue so I have narrowed it down to the amp. Anyone has any similar experiences with this issue? EDIT: After some reading, I think I have the thumping noise some people describe and apparently it has to do with the AC Adapter. Is there a one that one would recommend for the amp?
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Found this from JDS (https://www.jdslabs.com/pdf/Instructions_O2.pdf). This is the original avatar of your amp and hopefully identical except for the battery, which the Massdrop version doesn’t have. Note the minimum amperage mentioned. Check the adapter to see if this value is at or below the recommended minimum. Also, note the suggestion regarding a “stronger” adapter. I guess they mean with higher amperage. There is also a caution regarding overdriving the amp with certain sources or headphones. Two headphones with the same “nominal” impedance may draw different currents. Also, a headphone’s impedance alters depending on the music being driven through it. Let me know what music source you’re feeding into the O2 and if it has a “fixed” line-out. If the source has a manual that tells out the output from the line out, you may contact JDS asking if it is too much for the amp.
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Apparently JDS Labs has a new amp at $99, the Atom. Just found out from others, you guys might wanna check it out
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Well done indeed
Batteries. If I can't use it without an AC power source nearby, then the Atom doesn't fit my use case. For desktop with AC, I have my THX AAA 789.
wow....1 input.... even for $95 interface...the lack of features make this a friggen ripoff you're better off going for anything else. literally anything else. Most of the stuff on this site is a waste of money, but please be smart about this one guys.
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Do you usually spend your time online getting offended at statements not directed towards you? Get a life, yuppie.
How much do you think headphone amps should cost?
Can we expect to see more US 110V options? I am holding off buy the SDAC until I can purchase and objective 2 as well
What gain setting would be best with this a Topping D10 (2vrms) and dt990 600 ohms? Thanks.
Tommy_Vercetti
Hi I'd like to know this answer too? I've gone for the Medium gain version so far.
rosso
The medium gain version of the O2 would be optimal because the 2Vrms output of the DAC is maximized at the higher 3.3 gain provided by the medium gain version of the O2. The 6.5 gain on the standard version would be too high (use the 2.4 gain then with the standard O2). Remember that the max voltage recommended without getting distorsion on the O2 is 7V. Therefore the maximum gain to be used with a 2V source is 3.3 (2V x 3.3 gain = 6.6V < 7), otherwise you would exceed 7V with a higher gain setting like the 6.5 high gain on the standard O2. Most DACs have 2Vrms or 2.1Vrms maximum outputs. At 2.1V, the 3.3 gain setting is maximized (2.1V x 3.3 gain = 6.93V < 7). The 6.5 gain setting is optimized with 1Vrms outputs (1Vrms x 6.5. = 6.5V < 7) like iPhones, iPad and other low voltage portable equipment. Remember than both versions of the O2 may work out at least by using the lower 1.0 (medium version ) or 2.4 (standard version) gain but then you do not take full advantage of the 7V capacity that the O2 may provide in optimal setups.
Can someone post the size of the power plug/jack? I bought the 220VAC version and need to pick up a 120VAC wall wart.
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Spec on my O2 calls for 14VAC - 20VAC. Seems like it's in spec. 12 seems a bit weak.
Well, never mind what I just said, John @ JDS just came back and told me to get a 12VAC - 16 VAC transformer.
Hi, I'm trying to install batteries into the unit. Will any rechargeable battery work? How do I know if the batteries are fully charged? Has anyone successfully done this? TIA
aayushgoel92
Do not use 9v lithiums. Only the 9V NiMH will work if I recall
Did anyone ever figure out the issue with the continued thumping sound? I bought the O2 with a grace sdac. When I plug everything together I have a constant thumping sound in my earphones and chopped up audio if I try to play something. I got the NA version with the 12vac adapter. Thanks.
HELP So I just got the 220v medium gain version and i live in the US. When I plug it in and turn it on it makes a thumping sound, I think its coming from the power supply but have no ideas on where to go from here as i dont wanna kill my unit. What power supply do i need.
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Roen
Yeah I got it right after I bought my o2 now it works great no background noise and such, very loud. thanks
Ok, I just received mine today but having issues with it. It seems like I've made a mistake when ordering it. After researching why I was getting popping sounds with my headphones. I seem to have ordered the 220V version when I am in USA. The included power supply is 12VAC @ 220mA. This power plug gives me the popping/clicking sounds. I have another power plug that's 12V @2A but I only get silence from it. IS there anything I can do to make my Amp work correctly?
Himei
Same problem its a bassy thumping noise right? I have the 220v as well and im reading its the ac adapter. 220 is meant for Australia.
Hey guys so what should a US buyer do if they want the standard gain. Wait for another drop or buy the EU version and buy adapter separately? Or use battery? Thanks!
sercos
Buy EU and buy adapter separately. But from the sound of it, the 12V adapter is quite weak, so you'd want a stronger adapter regardless.
I got the sandard 220V standard gain but the included adaptor has a US type plug. Is it safe to connect it to a multiplug in EU mains? Or should I buy another adapter?
I missed out on standard gain again, damn.
I am pairing this with the HD58x (150ohm). I'll need to turn it to close 90% to get relative loud sound, but nothing wrong with that. If I switch to high gain, I can reach that same level of loudness with approx 40%. But the sound does appear to be different. Does switching b/t low/high gain affect the sound?
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EmpereHenri
The O2 has a gain switch to compensate for the voltage output of your source device. Depending on which gain settings you purchased you might not be able to use high gain without overloading the input regardless of the amps volume setting. It all comes down to this specific amp being a bit unusual to where its volume attenuation is placed in its topology. In other words leave on low gain unless you're using low power portable sources. More details from the man himself...! http://nwavguy.blogspot.com/2011/08/o2-details.html#maximuminput
Thank you! I guess the difference (if any) is minor, that after 10 mins of listening it would just be ignored.
I've found an european AC/AC adapter at home, and looks like it meets the requirements! But... Would this be Ok to use with this headphone amp and/or which problems could I have? Thanks!
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BigSome
I've crossed used adapters my whole life and never broke anything
BigSome
Is this a DC output adapter or an AC output adapter? (Looks like DC)
Anyone serious about headphone listening should seriously re-consider if looking at this amp. Real amps have real power supplies and real output circuits.
GUTB
Probably, but not at this price point and especially not at this form factor. It's a desktop edition amp but that doesn't change the fact that this amp was able to run off of batteries, and is still pretty good despite the low power required
GUTB
I'm not sure if you're trolling? This is a pretty useless comment. If you care to actually dig into understanding the value yourself, check out NwAvGuy's blog for the numerous writeups over the in-depth design process that they went through to develop this amp. As an engineer who has studied electronics, I can say I think NwAvGuy has done a great job. Also, I have some expensive cables to sell you ...
I am just trying to figure out the gain.
My 2.1 volt source will need 3.3x gain to get to the 7 volt maximum so I think that would be good.
FuckHead-Fi
I'm using this with a 2 V source, and I have the medium gain version. Works great, and I can engage the gain switch when needed, without worrying about clipping. Same will be true for your 2.1 V source. I haven't even needed to use the gain switch with any of my headphones (I don't have any that are especially thirsty) and there's plenty of juice for them all at low gain and without needing to crank the volume past 12 o'clock.
I recently purchased the Objectiv 2 Headphone Amp. Not sure how to connect to my computer. Any help out there?
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Not at all! I’m pretty easy going!
Edbarn
You generally want to feed it a clean source from the computer via a USB / SPDIF DAC. Feeding it directly from the computer's onboard audio will also amplify the EM interference from the motherboard.
Anyone have a recommendation for a portable battery powered DAC/amp for Android phone use? Seems like the few I checked didn't support up to the 300 ohms these are
Krustyboomer
I use a stack as portable. DAC - Topping D50 (powered by a USB battery pack) Amp - O2
Question: I would use mojo's line out as source. The EarPhone would be rs1e and k7xx. Which gain should I choose? Mid or Std? I was told the output of mojo's lineout is 3Vrms. They the only gain I could use is 1.0? Sound's bad...
Would it better to have this amp and the SDAC as a stack or have the combo unit??
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Do you have the standard gain or medium gain version?
superduperpupper
standard.
Question: I have a pro-ject debut carbon with a rega fono mini A2D pre-amp. Would medium gain be enough here for a set of Sennheiser HD6XX?
Does anyone know how well this amp pairs with the HD6XX?
toazt
Okay, it does make it sound quite thin, would recommend a magni 3 instead.