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Review and Measurements of Massdrop THX AAA 789 Amp

amirm

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Anyway, a question: any thought as to how the THX compares to a Musical Fidelity M1 HPAP? I didn't see any measurements for the MF when I did some looking about, but their other amps seem to measure pretty good.
Their spec has about an order of magnitude higher distortion than the THX. It is much nicer looking though.
 

Veri

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I was debating buying one at work today but decided naw. I just bought the $500 Gilmore Lite mk2 in December, I have no doubt the THX measures better but the Gilmore Lite mk2 is no slouch.

I've debated sending it to Amir for review to see how it measures up but then I would be stuck on my Asgard 2 :(
I would LOVE to see how the Gilmore does :D
 

Veri

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Ridiculous, again sold out within hours.... They are done for me, @amirm stop referencing to that one as it is not freely available, it's nonsense to put more and more people on that amp. Furthermore they should start adding some kind of an enhancement as this design is getting older..... I wish the Neuchrome stuff would be a bit cheaper as we in Europe have to add 1/3 to its price on top due to taxes and other fees.
Wait, how is this getting older? Wasn't its first drop and manufacturing completed in 2018...? Your expectations are a little high :p

I only wish they start offering A DAC+THX AMP combo since there is available space in the chassis, I suppose that will come over time.
 

Veri

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Maybe there will be a THX AAA 789 + SDAC-B sometime.
Now there's the big question. Will future massdrop DACs use the AK4493/AK4497/AK4499/new ESS all-in-one/exotic Cirrus Logic chips no other manufacturer but apple and sound blaster seem to care about :D

Or yeah. I'd guess they'll stick to the now old-gen AK4490, on the cheap.
 
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Now there's the big question. Will future massdrop DACs use the AK4493/AK4497/AK4499/new ESS all-in-one/exotic Cirrus Logic chips no other manufacturer but apple and sound blaster seem to care about :D

Or yeah. I'd guess they'll stick to the now old-gen AK4490, on the cheap.
Their SDAC-B (balanced) still uses the AK4452 just like the original SDAC (unbalanced). So I guess that for the moment they'll stick to it until some major SDAC revision comes in, but very well doubt that'll happen any time soon considering the SDAC-B hasn't even shipped for those who joined the first drop. :confused:
 

GoMrPickles

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The thing is, you can hear it. It's just masked by the dac. I have more than 19 friends said db magic ac3 has very wierd but realistic soundstage and vocal being upfront and has body. It's cheap. I measured all of those. including el dac focusritr forte. Only square wave is drastically different. Distortion are all below 0.0003%
I look forward to seeing your measurements! I don't think I'd be able to hear a difference between the ODAC and anything newer, but like I said, PM me if you want to ship me some gear.

The Allo Katana is $250; more if I want things like a case. At that price, I'd much rather get an SMSL SU-8 v2, and use XLRs between it and the THX. I am waiting to see if anything resolves the (also likely inaudible) ESS IMD hump. The Atom is almost too loud, if anything; I'm certainly not using it in its sweet spot (volume at like 9 o'clock).
 

maxxevv

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I only wish they start offering A DAC+THX AMP combo since there is available space in the chassis, I suppose that will come over time.
If I have both the THX (or the JDS ATOM) and the ( still missing somewhere in mail oblivion) Khadas Tone Board, I'm very confident I can fashion a handsome case to fit them together as a unit or as completely seamless stacks. ;)
 
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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.
Amir, I have already received the power supply that he advised buying (he plans to make some modifications to it now). Yet I am still scared that it might damage THX, as I am no engineer myself. Could you kindly advise on how dangerous it would be just to try as an experiment using a linear power supply with THX? I understand that it would void the warranty, but what are exact risks if I use the same voltage PS?

The power supply I intend to use has the following specs:

Output voltage from 2 to 30 V adjustable.
Current-carrying capacity - 2 A.
Nominal power - 200 V·А.
Maximum output voltage discharge - 2V.
Full output resistance - 10 Ohm.
 

JohnYang1997

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Amir, I have already received the power supply that he advised buying (he plans to make some modifications to it now). Yet I am still scared that it might damage THX, as I am no engineer myself. Could you kindly advise on how dangerous it would be just to try as an experiment using a linear power supply with THX? I understand that it would void the warranty, but what are exact risks if I use the same voltage PS?

The power supply I intend to use has the following specs:

Output voltage from 2 to 30 V adjustable.
Current-carrying capacity - 2 A.
Nominal power - 200 V·А.
Maximum output voltage discharge - 2V.
Full output resistance - 10 Ohm.
You need to compare the output voltage and type of both power supplies.
Type meaning ac or dc. If the original supply has ac output you cannot use dc.
The voltage means voltage. You can only go lower than higher.
Current output can only go higher and it's generally safe.

In this case as your output voltage is adjustable. You need to use multimeter to measure the voltage.
 

JohnYang1997

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Amir, I have already received the power supply that he advised buying (he plans to make some modifications to it now). Yet I am still scared that it might damage THX, as I am no engineer myself. Could you kindly advise on how dangerous it would be just to try as an experiment using a linear power supply with THX? I understand that it would void the warranty, but what are exact risks if I use the same voltage PS?

The power supply I intend to use has the following specs:

Output voltage from 2 to 30 V adjustable.
Current-carrying capacity - 2 A.
Nominal power - 200 V·А.
Maximum output voltage discharge - 2V.
Full output resistance - 10 Ohm.
Also in the case of dc, polarity is crucial. There is a dot in a half circle. - means negative + means positive. It has to be the same pattern as the original supply
 

szhchen

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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.
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
1549729311852.jpg
(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 .
20190130_195140.jpg
This stuff is some how expensive.but I am too busy to
DIY stuff recently.And this stuff is full refundable in my
place.
IMG_20190210_002617.jpg
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.
 
Last edited:

amirm

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Amir, I have already received the power supply that he advised buying (he plans to make some modifications to it now). Yet I am still scared that it might damage THX, as I am no engineer myself. Could you kindly advise on how dangerous it would be just to try as an experiment using a linear power supply with THX? I understand that it would void the warranty, but what are exact risks if I use the same voltage PS?

The power supply I intend to use has the following specs:

Output voltage from 2 to 30 V adjustable.
Current-carrying capacity - 2 A.
Nominal power - 200 V·А.
Maximum output voltage discharge - 2V.
Full output resistance - 10 Ohm.
Since this is a variable supply, you need a voltmeter to measure and set its output. Multimeters are pretty cheap. Get one from amazon, ebay, etc. Get one with auto-ranging so don't go to less than $10 meters. :)

Next you measure the THX power supply, putting the positive/red cable from multimeter in the center hole and the black on the outside. Note what that voltage is, and importantly if you see a negative for the shown value. Oh, the meter needs to be in DC volts. Maybe someone else can do this and report so you can skip this step.

After that, you do the same measurement with the supply you bought. Before powering on the new supply, plug it into the THX amp to make sure it fits and is snug. There are different sized connectors. Again, do this *before* you turn on the power supply.

Then disconnect the cable from the THX amp on the new power supply to the multimeter, connect the wires per above, and adjust the variable voltage potentiometer until it reads the same value as the original THX amp. And importantly, with the same polarity (i.e. if THX is positive, make sure it is positive with the new supply too). Getting the polarity right is *far* more important than getting the voltage right! Get a battery and test it with the meter, swap the wires back and forth and you see what I mean with polarity.

One the polarity and voltage are the same, then you can connect them to the THX amp. Turn the supply on, power on the THX amp and be ready to quickly disconnect if you smell anything burning, and/or popping sound.

If you like you can post pictures of measurements for each step we can help you with that too.

Chances of something going wrong is small if you blindly plug it in but if it does, given the shortage of units and cost of THX, you will have a lot of regrets. :)
 

Veri

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Chances of something going wrong is small if you blindly plug it in but if it does, given the shortage of units and cost of THX, you will have a lot of regrets. :)
That is indeed an important thing to consider :)
 
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Since this is a variable supply, you need a voltmeter to measure and set its output. Multimeters are pretty cheap. Get one from amazon, ebay, etc. Get one with auto-ranging so don't go to less than $10 meters. :)

Next you measure the THX power supply, putting the positive/red cable from multimeter in the center hole and the black on the outside. Note what that voltage is, and importantly if you see a negative for the shown value. Oh, the meter needs to be in DC volts. Maybe someone else can do this and report so you can skip this step.

After that, you do the same measurement with the supply you bought. Before powering on the new supply, plug it into the THX amp to make sure it fits and is snug. There are different sized connectors. Again, do this *before* you turn on the power supply.

Then disconnect the cable from the THX amp on the new power supply to the multimeter, connect the wires per above, and adjust the variable voltage potentiometer until it reads the same value as the original THX amp. And importantly, with the same polarity (i.e. if THX is positive, make sure it is positive with the new supply too). Getting the polarity right is *far* more important than getting the voltage right! Get a battery and test it with the meter, swap the wires back and forth and you see what I mean with polarity.

One the polarity and voltage are the same, then you can connect them to the THX amp. Turn the supply on, power on the THX amp and be ready to quickly disconnect if you smell anything burning, and/or popping sound.

If you like you can post pictures of measurements for each step we can help you with that too.

Chances of something going wrong is small if you blindly plug it in but if it does, given the shortage of units and cost of THX, you will have a lot of regrets. :)
Dear Amir, thank you for your detailed response. I will ask that guy to do this check with a voltmeter in my presence before turning the unit on with the new supply. I do understand what's at stake, that is why I contacted you and Andrew from THX to ensure that all reasonable precautions are taken.
 
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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.
What amplifier exactly did you mean af200?
 
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