• WANTED: Happy members who like to discuss audio and other topics related to our interest. Desire to learn and share knowledge of science required as is 20 years of participation in forums (not all true). Come here to have fun, be ready to be teased and not take online life too seriously. We now measure and review equipment for free! Click here for details.

Review and Measurements of Massdrop THX AAA 789 Amp

Roen

Senior Member
Joined
Oct 14, 2018
Messages
443
Likes
133
A different power supply definitely improve the THX sound quality according to my experience.

There is no noise heard with the original power supply come with THX.
But the imaging is big and not condensed.

In fact I am also confused to the issue I heard. Since the measurement is inaudible and near perfect.
But I have lend THX to my friend for over a week. And I didn't told him any thoughts about this amp.
It turns out that he has notice the same issue.

headphone mainly use: Z1R, A2000Z, SRH-1840, TH-X00
compared amp: Jotunheim, Gustrad H20, iFi Pro iCAN
DACs: Grace m9xx. Pioneer N70A

The issue persists with and DACs and headpones. And only with THX.
I thought THX is just tuned like this.And everyone just love it.So no one complains.
Until I go power supply change for fun as usual.

I tried a probably poor quility 24v 0.5A LDO for other device.
cost $60
View attachment 21613
(YES I aware 0.5A is low.buy i don't believe THX consume that much
since the machine is no heat coming out :p)

This improve some image issue.But bass texture was fucked up.
So I figure out the image issue comes from power supply.

I give iFi DC iPurifier2 a shot .
View attachment 21617
This stuff is some how expensive.but I am too busy to
DIY stuff recently.And this stuff is full refundable in my
place.
View attachment 21615
Finally the sound imaging condensed.just like making the focus right in photo.
But one thing must aware is iFi DC iPurifier2 gets very hot working and even with THX shutdown over night.
Probably 60~70 degrees Celsius.Might need to find transformer with switch to use with this.
You know we're going to have to ask for measurements right?
 
Joined
Dec 28, 2018
Messages
94
Likes
14
You compared Accurate Audio HPA-A200 with the original Violectric HPA V200. Are there big differences in sound?
I don't think there's anything big but there should be. I don't buy into the original being the best stuff. If it measures well then it is. Before i modified o2, a200 and af200 are my recommendations for my friends. So a couple of them bought a200 and happy. af200 is more expensive but i think it's better built, closer matched transistors. So yeah. But it's twice as expensive tho. about 2400 cny.
 
Joined
Jan 14, 2019
Messages
26
Likes
4
Atom is a great amplifier, but I do not like clinical sound. I read somewhere that Atom sounds like that. Hence the direction of V200
 
Joined
Dec 28, 2018
Messages
94
Likes
14
Atom is a great amplifier, but I do not like clinical sound. I read somewhere that Atom sounds like that. Hence the direction of V200
Amplifiers imho do have sound. But the difference is still rather small comparing to headphones. If you get a pair of great sounding headphones to your liking it will sound good.
 
Joined
Dec 28, 2018
Messages
94
Likes
14
I bought my A200 on Taobao, manufacturer refurbished version, for 1000 CY, it's around 155 USD.
The refurbished ones are essentially second handed ones. The seller/builder discontinued the a200 so he bought back some second hands and resell them. Not bad deal especially for the price. And you can swap some opamps for better measurements.
opa827 for input and opa227p for the ones nesr the output transistors.
 
Joined
Dec 4, 2018
Messages
30
Likes
9
The refurbished ones are essentially second handed ones. The seller/builder discontinued the a200 so he bought back some second hands and resell them. Not bad deal especially for the price. And you can swap some opamps for better measurements. opa827 for input and opa227p for the ones nesr the output transistors.
Great advice! I'll write PM to you on the matter now.
 
Joined
Jan 14, 2019
Messages
26
Likes
4
Top Bottom