Review and Measurements of Massdrop Alex Cavalli Tube Hybrid (CTH) and JDS O2 Headphone Amps

[amirm]

@amirm was the O2’s gain on 1x or 2.5x(default) during testing?

All tests except channel imbalance were in high gain.

 

[amirm]

Wait. Did you send the NX4 back to me?
Or, are you talking about opening it up to look under the hood and compare visually?

Oops. I thought I had sent it back but was still sitting on my shipping table. sorry about that.

 

[Headphonaholic]

This review was a pleasant surprise to see up! I've been waiting to see how the o2 does since I own 2 (1 at work and 1 at home). I also own the CTH so I was pleased to see it being measured but also a bit disappointed with its performance.

I will say that I'm not surprised that it's not running the tube fully since it doesn't get as warm as a real tube amp and I've also heard no real change in sound when tube rolling.

And to the person that was trying to argue tube amps use little power bricks, I own 3 real tube amps and all of them just take a standard iec power cord and have big transformers. Now I also own a Little Dot mk1 that takes an iec cord and has what I assume is a transformer box on it. So it potentially runs the tubes at correct voltages. Not sure. I'll be sending it to Amir soon so he can measure and open it up.

 

[PuX]

great review as always.

a note regarding pricing: CTH is normally sold for $250, while a basic O2 can be bought from JDSLabs for $130 or configured to up to ~$200. also Massdrop sells their version of O2 for $95 (made in China + not a great power adapter judging from reviews, but configured for desktop use).

if you ever get a chance to test Schiit Magni (3?) keep the same settings, it would be nice to see how it compares. supposedly it has more power but knowing them I have doubts about that.

by the way, does the gain setting actually influence the measurements? I heard it's best to use the low gain if it can power your headphones loud enough.

 

[Veri]

great review as always.

a note regarding pricing: CTH is normally sold for $250, while a basic O2 can be bought from JDSLabs for $130 or configured to up to ~$200. also Massdrop sells their version of O2 for $95 (made in China + not a great power adapter judging from reviews, but configured for desktop use).

Note that the Chinese/Massdrop O2 supposedly uses some different parts which are actually in breach of Nwavguy's free use policy (no changes to be made to his design).

 

[amirm]

if you ever get a chance to test Schiit Magni (3?) keep the same settings, it would be nice to see how it compares. supposedly it has more power but knowing them I have doubts about that.

I did test it a bit a while ago against the O2 and it indeed had more power. But I need to properly test and compare it against O2.

 

[amirm]

by the way, does the gain setting actually influence the measurements? I heard it's best to use the low gain if it can power your headphones loud enough.

It can impact the noise measurements. That is, the part of the THD vs power curve that is sloping down.

It is very time consume to cover all combinations of settings, volume control and input levels.

 

[mi-fu]

Oops. I thought I had sent it back but was still sitting on my shipping table. sorry about that.

Amir, do you think it is possible to test the O2 against NX4 DSD if it is still lying around?

 

[amirm]

Amir, do you think it is possible to test the O2 against NX4 DSD if it is still lying around?

Yes, I will do a couple of spot checks.

 

[PuX]

Note that the Chinese/Massdrop O2 supposedly uses some different parts which are actually in breach of Nwavguy's free use policy (no changes to be made to his design).

that's also a bit concerning. I thought all they changed was the power supply, rca out and power in sockets and the headphone jack (all should be ok except power supply which is 12V I think).

It is very time consume to cover all combinations of settings, volume control and input levels.

makes sense. I like your approach to match the levels at some reasonable point across different devices.

btw, I'm slightly surprised with the higher power of iFi. still O2 should be powerful enough for any headphones, even 600Ohm ones, right? unless one needs it to be very loud. or does iFi provide something more than extra loudness? i.e. maybe its power delivery is effortless or something like that?

 

[amirm]

btw, I'm slightly surprised with the higher power of iFi. still O2 should be powerful enough for any headphones, even 600Ohm ones, right? unless one needs it to be very loud. or does iFi provide something more than extra loudness?

I like it very loud! Actually I did not know I wanted it that loud until I played the iFi. The sensation of the cups physically moving back and forth is something else.

But yes, by most standards, the O2 was loud enough. It just couldn't make the headphones cry.

 

[TungstenC]

Note that the Chinese/Massdrop O2 supposedly uses some different parts which are actually in breach of Nwavguy's free use policy (no changes to be made to his design).

Doesn’t look like there was any changes at all in my O2 either way they seem to have fixed it.

https://www.reddit.com/r/Massdrop/comments/7ny0vj
*This is a teardown from somebody else’s O2+SDAC but both O2 drops should be the same minus the SDAC board.

 

[Jimster480]

Note that the Chinese/Massdrop O2 supposedly uses some different parts which are actually in breach of Nwavguy's free use policy (no changes to be made to his design).

Wow I never knew this. It would be interesting to get one and test it.
I have a JDS O2 and use it basically every day along with my A30 & DX7...
I have no complaints after a year of use, outside of the fact that it makes a pop when you turn the amp on. Meaning I have to unplug headphones when I turn it on/off.

 

[Veri]

Doesn’t look like there was any changes at all in my O2 either way they seem to have fixed it.

https://www.reddit.com/r/Massdrop/comments/7ny0vj
*This is a teardown from somebody else’s O2+SDAC but both O2 drops should be the same minus the SDAC board.

Interesting link but note that the O2+SDAC version is by Grace Design as seen on the teardown. I'm pretty sure the regular O2 drop has nothing to do with Grace Design. I've not yet seen a teardown of the traditional O2 massdrop unit.

 

[Kyle / MrHeeHo]

Interesting link but note that the O2+SDAC version is by Grace Design as seen on the teardown. I'm pretty sure the regular O2 drop has nothing to do with Grace Design. I've not yet seen a teardown of the traditional O2 massdrop unit.

I don't see why they would redesign the O2 and then make a product later that follows the specs. This is likely the same board sold in the regular O2 drop, just with an SDAC board included.

 

[PuX]

Interesting link but note that the O2+SDAC version is by Grace Design as seen on the teardown. I'm pretty sure the regular O2 drop has nothing to do with Grace Design. I've not yet seen a teardown of the traditional O2 massdrop unit.

it's exactly the same as the regular massdrop version except they slapped an extra DAC board on top of the amp board.

Doesn’t look like there was any changes at all in my O2 either way they seem to have fixed it.

there was at least one batch where they confused the gain settings for this DAC/amp combo. it was supposed to be x1 and x3.3 and they used x2.5 and x6.5 (the default one from the original design). and since the DAC outputs 2V in this case x1 and x3.3 is more appropriate. I read this on massdrop comments.

 

[Grave]

Just buy the JDS Labs version, its build quality is great.

https://www.jdslabs.com/products/35/objective2-headphone-amplifier/

 

[Ron Texas]

I thought Amir was NWAVGUY, LOL. Tubes increase well being, well they might in a cold house on a winter's night. Thanks for another great set of measurements.

 

[TungstenC]

I thought Amir was NWAVGUY, LOL...

Amirm + Car Analogy = NwAvGuy?

 

[Wombat]

I like it very loud! Actually I did not know I wanted it that loud until I played the iFi. The sensation of the cups physically moving back and forth is something else.

But yes, by most standards, the O2 was loud enough. It just couldn't make the headphones cry.

Or make you partially deaf.