Massdrop x THX AAA™ 789 Linear Amplifiersearch

Massdrop x THX AAA™ 789 Linear Amplifier

Massdrop x THX AAA™ 789 Linear Amplifier

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THX Ltd. started as a company with a directive to ensure that upstream quality in cinema audio made it all the way to the audience in the theater.
In the movie theater, you need great power in order to get the dynamic range needed for impactful music and action...with a very low noise floor and low amounts of distortion in order to hear crisp dialog and all the detail in the recording.

Patrick Flanagan at THX is one of those quiet guys who goes about his business with an engineer’s mind and a craftsman’s attention to detail. You may have met him at a Head-Fi meet in California as Jude Mansilla has been able to have him offer some free headphone or IEM measurements to the community on multiple occasions.

We met him at the 2016 SF Head-Fi Meet where he provided us with some measurements of IEMs we were working on:
THX provides development and certification services to ensure that a whole range of audio products meet objective performance and quality metrics from frequency response to low distortion, with the goal of accurate sound reproduction.

New Technology
The Massdrop x THX Achromatic Audio Amplifier (THX AAA™) 789 represents the next chapter in THX contribution to the audio world, where THX provides underlying circuit technology in the gear itself.
The new design was born of necessity. THX needed amplifiers to power line arrays of speakers in their facility. Class A topology amplifiers run too hot and are inefficient to run for long periods of time. THX needed the cleanest signal possible, low noise, low distortion, cool temperature, and efficient power consumption. These requirements led THX and SVP of Audio R&D Laurie Fincham to revisit negative feedback designs, figure out how to implement feed-forward correction, and create the quietest, lowest distortion amplifiers.

THX Ltd. At-A-Glance:
I. Highest quality sound for the utmost in cinematic experience (George Lucas’ original vision)
II. Development and certifications for pro audio and audiophile gear (people like Patrick)
III. Technological intellectual property in pro and consumer gear (Laurie Fincham’s amplifier design as an example)

A Series of Fortunate Events
If we didn’t talk about Patrick, you might not know that THX is working every day behind the scenes to provide information to companies making audio gear…with and without the THX logo. And if we didn’t meet Patrick, this collaboration might not have happened.

Meeting Patrick at the event pictured above led to our visiting THX and seeing some of the measurement labs plus their demo room. (Fun stuff and just happens to be walking distance from our office in San Francisco!)

Visiting their headquarters led to an invitation for a sneak peek of the THX AAA feed-forward topology during the Rocky Mountain Audio Festival in Colorado 2016.
We immediately saw the potential of this amplifier technology when we learned about it’s goals. Hearing the prototype- clean, clear, and natural (not sterile)...we knew that our community would like it too.

THX understands Massdrop’s connection with the headphone audiophile community and our drive to create custom-tailored products. THX collaborated with us to develop and bring this linear amplifier technology to you in this particular package, with the flexibility for in-ear monitors to large headphones. Capable for use in professional audio applications or for the audiophile that demands the most transparent upstream gear possible. This amplifier delivers the upstream quality of your music to your own personal headphone theater- in the comfort of your home or on your desk at work.

Massdrop x THX AAA 789 Linear Amplifier At-A-Glance:
I. Lowest THD in class – world class transparency
II. Extremely low channel crosstalk
III. From low to high power – for your IEMs and your hard-to-drive headphones
IV. Flexibility – from single-ended input/output to fully balanced throughput
V. Form factor and usability - small, cool, efficient energy consumption
VI. High value – high power and best performance at a low price point
By the way, we’re lucky to have Andrew Mason as a member here on Massdrop. Andrew is the THX expert in analog & power engineering who helped implement the THX AAA technology into our final product. If you have some technical questions about the amplifier, Andrew may just be around to answer them!
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Andrew we need another drop, Monoprice's Dual THX788 Headphone Amp is delayed Oct and its been pushed out further twice :-(
Andrew whats the difference between 788 vs 789? Does have dual balanced 788's have greater quality, performance than what appears to be one 789 in this Massdrop version?
Jude getting some measurements to us...will try to post here as soon as I can!
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Does this product have a burn-in time before giving 100% performance?
Caps forming etc, is it mumbo-jumbo?
Hi rajapruk
It wouldn't change the noise. Perhaps the 20-40 Hz distortion might get even lower.

No burn in time is required for the 789. I have a more detailed post on this in this forum.
This update is for members who joined the drop in March:

Hi everyone,
The Massdrop x THX AAA™ 789 Linear Amplifier is making its way through production! We also have some important updates to share about the gain specifications.
We worked with THX to adjust the gains for the primary use case of the Audiophile community. Previously, the gains were optimized for variance in source output power. Most Audiophiles typically use 2V DAC sources and wish to drive in-ear monitors or hard-to-drive headphones.
With these slight changes there were some updates to the gain specifications, which we have listed below:
  • Frequency response: + 0.01 dB / - 0.03 dB 20 Hz–20 kHz; + 0.05 dB / - 0.15 dB 10 Hz–50 kHz
Balanced Output:
  • THD: -130 dB, 32 ohms, 1 mW: 0.000032%
  • THD: -130 dB, 32 ohms, 100 mW: 0.000032%
  • THD: -122 dB, 16 ohms, 1 mW: 0.000080%
  • THD: -122 dB, 16 ohms, 100 mW: 0.000080%
  • Gain: 0.66x , 2.0x, 6.6x (-4, +6, +16 dB), selectable via front switch

Single-Ended Output:
  • Output power: 1800 mW, 32 ohms, <1% THD (watts per channel)
  • THD: -135 dB, 300 ohms, 100 mW: 0.000018%
  • THD: -133dB, 32 ohms, 100 mW: 0.000022%
  • THD: -130 dB, 16 ohms, 1 mW: 0.000032%
  • THD: -125 dB, 16 ohms, 100 mW: 0.000056%
  • Gain: 0.33x , 1.0x, 3.3x (-10, 0, +10 dB), selectable via front switch

We’re on track to meet our estimated ship date of October 31, and we'll check back in around the middle of October with the status of the shipment.
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Hi Andrew. Thanks for the reply. I haven't gotten a cable yet, but I do intend to run these balanced via xlr once they come in. Can't wait to receive the amp and give it a listen.
Could you please expand on where you are in the production process? We were assured months ago that the design for this product was "locked in", and your last update presented design changes. Are additional design changes still being made? Which parts of the amp have been physically manufactured and which are still awaiting production? Another electronics drop with a 6-month lead time that I'm currently waiting for announced delays from design changes to its pcb and chassis right when it was supposed to be shipping, so I'm concerned about the process Massdrop follows. Some more insight into where you are in the process (and what exactly "on track" means) would be appreciated.
For the cabling in my system to be good, I would like an output on the backside of the unit, like this:
Maybe I can mod the chassis like this. We will see :)
This would honestly be a godsend, it is unlikely for there to be a change this late however. Plus, they wouldn't mind if you upgraded to the THX-888 HPA4 ($3000) which features XLR passthrough and line-control :D
I will not downgrade to something with a ugly screen on it!
Will you have a sample at RMAF next month to listen to? I will be there and love here what I will be getting.
Bill-P has posted his review on SBAF (which I wanted to see before the end of last drop) and now I'm waiting for another drop...
Is there a specific DAC THX recommends for this? I bought this but I have no DAC and will need to wait for it to drop...
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I was thinking about massdrops R2R Airist. I do have the Creative X7 with Burr Brown PCM1794

24-Bit Resolution
Analog Performance: − Dynamic Range: 132 dB (9 V RMS, Mono) 129 dB (4.5 V RMS, Stereo) 127 dB (2 V RMS, Stereo)
− THD+N: 0.0004%
Differential Current Output: 7.8 mA p-p
8× Oversampling Digital Filter: − Stop-Band Attenuation: –130 dB − Pass-Band Ripple: ±0.00001 dB  Sampling Frequency: 10 kHz to 200 kHz
System Clock: 128, 192, 256, 384, 512, or 768 fS With Autodetect
Accepts 16- and 24-Bit Audio Data
PCM Data Formats: Standard, I2S, and Left-Justified
Optional Interface Available to External Digital Filter or DSP
Digital De-Emphasis
Digital Filter Rolloff: Sharp or Slow
Soft Mute
Zero Flag
Dual-Supply Operation: − 5-V Analog, 3.3-V Digital
5-V Tolerant Digital Inputs
Small 28-Lead SSOP Packag

My motherboard has the ES9023 which isn't half bad.
I'm in the drop for MD Airist R2R to be paired with MD CTH.
This has THD+N of 0.08% which is a bit high, so i'm not sure if it would pair well with THX AAA - I'd imagine any imperfection of the R2R would be transparent through the AAA. I'd wait for the reviews before considering it.

AndrewMason Thanks for sharing about the Topping NX4-DSD. That one seems to measure quite well at <0.0008% THD+N and cheaper.
Only 2 more months until it ships! Who else is giddy with excitement?
Just to clarify, is the Schiit Magni 3 more powerful than this?, specs,
Maximum Power, 16 ohms: 3W RMS per channel
Maximum Power, 32 ohms: 2W RMS per channel
Maximum Power, 50 ohms: 1.3W RMS per channel
Maximum Power, 300 ohms: 430mW RMS per channel
Maximum Power, 600 ohms: 230mW RMS per channel
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Yes, I understand. Magni 3, doesn't even have balanced outputs, so no comparison there.
I recently bought a Magni 3, but i find that it doesn't do any better than my Oppo 105 headphone amp . As i have joined the drop on this, i am wondering if i should keep the Magni 3 or send it back and eat the re-stocking fees :)

Not sure what to tell you there. I have not heard it, so I can't really draw comparisons between the two.