• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required. There are many reviews of audio hardware and expert members to help answer your questions. Click here to have your audio equipment measured for free!

Review and Measurements of Massdrop THX AAA 789 Amp

Music1969

Major Contributor
Joined
Feb 19, 2018
Messages
4,645
Likes
2,813
The good news is Massdrop has jumped in will be shipping out a replacement in next 1-3 days and then will print the prepaid UPS tag to return the failed unit.

So hopefully the new amp will last for a long time.

Support for this product is 1st class. I've had a minor unrelated issue with my THX 789 amp and support was first class.

This 789 amp is something special. Insanely great. I have it paired with Pro-Ject Pre Box S2 DAC.

I'd never purchased anything from Massdrop before and being on the other side of the world, I was worried support would be an issue. And I read some comments about channel imbalance.

Both fears have been squashed - very very happy.

If there's a followup with remote control and maybe digitally controlled analogue volume, I'd probably still upgrade just to feel warm and fuzzy inside. If there's no followup to this one, I'm already so happy, so no problems.
 

ReAlien

Active Member
Joined
Dec 4, 2018
Messages
105
Likes
17
How are these clone amps, with respect to internal part quality, power supply, etc.? I was curious about the A281 off taobao?

Sorry, lost your comment as the website did not email me a proper notification for some reason.

I cannot comment on internal parts quality or power supply as I'm not a technical guy. I bought it because I've heard it in one of the local shops and liked it immensely. I have never listened to its original, Violectric V200, so cannot compare and comment on how close they are soundwise. But I've heard from other people that differences are minuscule.

Yet I can say for sure that even without balanced HP output it is better than THX in some aspects. I had loaned it to a friend for several days and had been listening only to THX. Today, I started listening to it again and I can say that it's sound definitely has more body and emotion than THX's one, the bass is particularly more pleasant and punchy. It lacks THX clarity and detail though. That is why I decided to leave them both for now and listen to them in a rotation.

And that is why I am considering buying a different power supply for THX, transformed based one with a large torus. Its addition should improve THX's lack of body issue, supposedly.
 
Last edited:

ReAlien

Active Member
Joined
Dec 4, 2018
Messages
105
Likes
17
I wouldn't buy it and much less at the asking price, they are trying to profit from someone elses work and who knows what's inside.

Yeah, I do understand that it is a rip-off on the Chinese part, but I live in a third-world country with widespread piracy habits, we're trying to compensate for low salaries level in whatever way we can. I guess that is my sin I am going to burn for. :rolleyes:

As to "who knows what's inside", I listened to it before buying so I knew what I was getting into.
 

Veri

Master Contributor
Joined
Feb 6, 2018
Messages
9,596
Likes
12,036
And that is why I am considering buying a different power supply for THX, transformed based one with a large torus. Its addition should improve THX's lack of body issue, supposedly.

There is no power supply problem whatsoever... there is ZERO incentive to get a different supply? Objectively what do you hope to attain??

Screen Shot 2019-02-04 at 14.12.00.png
 

ReAlien

Active Member
Joined
Dec 4, 2018
Messages
105
Likes
17
There is no power supply problem whatsoever... there is ZERO incentive to get a different supply? Objectively what do you hope to attain??

I met a guy, who's into DIY amping and he liked THX clarity yet I agree with him that its sound lacks body. As per his opinion, a powerful transformer-based PS would improve its sound. We agreed that he would demonstrate to me at least part of improvements before I decide on going this way. I will report any progress.
 

Veri

Master Contributor
Joined
Feb 6, 2018
Messages
9,596
Likes
12,036
I met a guy, who's into DIY amping and he liked THX clarity yet I agree with him that its sound lacks body. As per his opinion, a powerful transformer-based PS would improve its sound. We agreed that he would demonstrate to me at least part of improvements before I decide on going this way. I will report any progress.
I have some Jensen transformers on the way myself. to check its effect on actual sound, but transformers in the power supply line that is already filtered and regulated to a GREAT extent seems almost hilariously pointless to me. Amir shows its performance with the supplied brick, is way above any DAC measured so far at 116dB SINAD. An external brick cannot improve from there.. lack of "body" or not.

This amp is simply transparent that's all there is to it. If you want transformers get RCA/XLR ones :p
 
Last edited:

Veri

Master Contributor
Joined
Feb 6, 2018
Messages
9,596
Likes
12,036
I met a guy, who's into DIY amping and he liked THX clarity yet I agree with him that its sound lacks body. As per his opinion, a powerful transformer-based PS would improve its sound. We agreed that he would demonstrate to me at least part of improvements before I decide on going this way. I will report any progress.

Screen Shot 2019-02-04 at 15.09.28.png
 

ReAlien

Active Member
Joined
Dec 4, 2018
Messages
105
Likes
17
An external brick cannot improve from there.. lack of "body" or not.

I am well aware that such change of power supply would void warranty. And there is no plan to increase the voltage of 24V. Yet this engineer insists that there is a room for improvement and that it is a safe test so I'm going to attempt it. If you have any technical comments, I could pass those to him no problem.
 
OP
amirm

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
44,376
Likes
234,556
Location
Seattle Area
I am well aware that such change of power supply would void warranty. And there is no plan to increase the voltage of 24V. Yet this engineer insists that there is a room for improvement and that it is a safe test so I'm going to attempt it. If you have any technical comments, I could pass those to him no problem.
Some power supply designs have a turn-on voltage peak before regulation kicks in. Make sure whatever he designs doesn't have an "overshoot" on that (or when turning off). Have him show that to you with a scope output.
 

maxxevv

Major Contributor
Joined
Apr 12, 2018
Messages
1,872
Likes
1,964
I met a guy, who's into DIY amping and he liked THX clarity yet I agree with him that its sound lacks body. As per his opinion, a powerful transformer-based PS would improve its sound. We agreed that he would demonstrate to me at least part of improvements before I decide on going this way. I will report any progress.

How do you define "lacks body".. ? And what was it referenced to ?

As demonstrated by the Darkvoice review, sometimes a perceived sound signature is really just an after effect of distortions caused by issues like
i) distortions in the output
ii) poorly matching output impedances to headphones causing shifts in transducer frequency response.

You may very well be chasing a false shadow if the reference point is not clearly defined.
 

ReAlien

Active Member
Joined
Dec 4, 2018
Messages
105
Likes
17
Some power supply designs have a turn-on voltage peak before regulation kicks in. Make sure whatever he designs doesn't have an "overshoot" on that (or when turning off). Have him show that to you with a scope output.
Thanks for the advice! He says it is an obvious matter, though.) Current plan is to use some old Soviet design PS (featuring fine voltage regulation and germanium stabilizer), which he would tweak for my purposes.


How do you define "lacks body".. ? And what was it referenced to ?

As demonstrated by the Darkvoice review, sometimes a perceived sound signature is really just an after effect of distortions caused by issues like
i) distortions in the output
ii) poorly matching output impedances to headphones causing shifts in transducer frequency response.

You may very well be chasing a false shadow if the reference point is not clearly defined.
Well, it is always difficult to put in words your feelings or sensations. "Body" for me means thicker, fuller sound of instruments, like all of them gain "weight" and sound more mature and solid.

I am referencing THX to my other headphone amp Accurate Audio A200, which definitely has more full-bodied sound in A/B comparison.

I don't know what this guy is referencing to but when I first met him he let me listen to his Abyss AB-1266 on my THX, which means he's on an entirely new level of audiophilia than me.)))
 

maxxevv

Major Contributor
Joined
Apr 12, 2018
Messages
1,872
Likes
1,964
You haven't mentioned the headphone used though.

You do realise that your A200 is a clone of the Lake People Vioelectric V100 right ? At least its a complete clone on the outside, no idea what's inside comparatively. So, you might not be hearing what you should in terms of reproduction transparency.

As for the Abyss Phi , its supposed to be one demanding headphone in terms of power requirements. I have heard it, at a local distri's demo quite a while back, but I haven't had any chance to play with it on a lesser amp. ( The demo was connected to a Blue Hawaii ) But according to the demo guy, it needs a load of power, more than any they have including all of Hifiman's least sensitive planars that they sell. How well or sufficiently the THX copes with that is an unknown to me. But there is a possibility that there isn't quite enough power headroom for the Abyss for it to sound "ideal".
 

ReAlien

Active Member
Joined
Dec 4, 2018
Messages
105
Likes
17
You haven't mentioned the headphone used though.

You do realise that your A200 is a clone of the Lake People Vioelectric V100 right ? At least its a complete clone on the outside, no idea what's inside comparatively. So, you might not be hearing what you should in terms of reproduction transparency.

As for the Abyss Phi , its supposed to be one demanding headphone in terms of power requirements. I have heard it, at a local distri's demo quite a while back, but I haven't had any chance to play with it on a lesser amp. ( The demo was connected to a Blue Hawaii ) But according to the demo guy, it needs a load of power, more than any they have including all of Hifiman's least sensitive planars that they sell. How well or sufficiently the THX copes with that is an unknown to me. But there is a possibility that there isn't quite enough power headroom for the Abyss for it to sound "ideal".

I'm using HE560 v2 now. A200 is a full clone of V200, not V100. Inside they also look the same, you can check pictures on the web. I do understand that it might be not on par with original V200 due to some parts being not identical but in terms of it having more full-bodied sound than THX it is even more telling. :)

Abyss 1266 has 45 Om with max 4W input capability and THX is giving out around 4W in balanced mode at such resistance level, so I guess it is quite capable of driving it if not to full but close to full potential. Anyways, this DIY amp engineer listened to my THX on several cans, including my HE560 and his Edition X as well.
 

BurritoJustice

Active Member
Forum Donor
Joined
Oct 1, 2018
Messages
100
Likes
195
If the 789 can drive HE6, which it can, then it can drive the Phi as the Phi is a good chunk more sensitive.

I'm basing my statement on the HE6 from my own experience (I own the relevant parts), but also mathematically (4w recommended max, 3.8w from the 789), and subjectively there are many on Head-Fi who claim the same. As far as efficiency goes, I'm basing my statement off of Innerfidelity's measurements.
 

headwhacker

Active Member
Forum Donor
Joined
Dec 25, 2018
Messages
165
Likes
224
I have the HE-6. I throw everything at it (music genre-wise) driven by my THX amp and it can drive the HE-6 with a spare more power. Before getting my THX amp I'm using the Violectric V280 (about 3.2W @ 50Ohms) and I find it very sufficient with HE-6.

At lot of people on other forums swear on their dead granny's grave that you need a speaker amp to drive the HE-6 properly. Well I tried that as well with Marantz PM5005. All I can say is it sound different on the PM5005 probably due to distortions I can hear on top of the actual music. Yes it's pleasant sounding but I think you sacrifice resolution and/or clarity which is more important to me in terms of enjoying music.

I can be wrong and they probably do sound the same with level-matched blind testing.
 

BurritoJustice

Active Member
Forum Donor
Joined
Oct 1, 2018
Messages
100
Likes
195
Power requirements are overstated, I have used my HE6se straight out of my damn Nintendo Switch.

It's not loud, but it's perfectly serviceable. Some sources just literally do not function though, the headphone output on my monitor (a PG279Q, for computer nerds) is completely inaudible no matter the context with the HE6.
 

Veri

Master Contributor
Joined
Feb 6, 2018
Messages
9,596
Likes
12,036
I have the HE-6. I throw everything at it (music genre-wise) driven by my THX amp and it can drive the HE-6 with a spare more power. Before getting my THX amp I'm using the Violectric V280 (about 3.2W @ 50Ohms) and I find it very sufficient with HE-6.

At lot of people on other forums swear on their dead granny's grave that you need a speaker amp to drive the HE-6 properly. Well I tried that as well with Marantz PM5005. All I can say is it sound different on the PM5005 probably due to distortions I can hear on top of the actual music. Yes it's pleasant sounding but I think you sacrifice resolution and/or clarity which is more important to me in terms of enjoying music.

I can be wrong and they probably do sound the same with level-matched blind testing.

Excellent info :)
 

JohnYang1997

Master Contributor
Technical Expert
Audio Company
Joined
Dec 28, 2018
Messages
7,175
Likes
18,292
Location
China
I'm using HE560 v2 now. A200 is a full clone of V200, not V100. Inside they also look the same, you can check pictures on the web. I do understand that it might be not on par with original V200 due to some parts being not identical but in terms of it having more full-bodied sound than THX it is even more telling. :)

Abyss 1266 has 45 Om with max 4W input capability and THX is giving out around 4W in balanced mode at such resistance level, so I guess it is quite capable of driving it if not to full but close to full potential. Anyways, this DIY amp engineer listened to my THX on several cans, including my HE560 and his Edition X as well.
The body you hear is the low frequency ps noise. I have af200 which is a better clone of v200 and i have person tested the original or me as well, they both have -100dbv ps noise. Which is very audible to sensitive earphones and will impact other headphones in some ways. -100dbv is audible because it doesn't change along with volume pot.
 
Top Bottom