Massdrop x THX AAA™ 789 Linear Amplifier - Impressions Thread
Mar 1, 2018 at 7:04 PM Thread Starter Post #1 of 2,607

XERO1

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thx aaa 789.png

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Here's what the current Drop version looks like:
3DqzUl0oRZarp7AjHDys_1500x1000_MD-93913_01.jpg
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https://drop.com/buy/drop-thx-aaa-789-linear-amplifier

https://www.audiosciencereview.com/...easurements-of-massdrop-thx-aaa-789-amp.5001/
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The Massdrop x THX AAA 789 is finally here and it's pretty incredible! :grinning:

If you're looking for an affordable ultra-neutral, super-transparent amp with plenty of power, then the 789 should be at the top of your list.

Discuss!

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Edit: Massdrop has changed it's name to Drop, so this amp is now called the Drop x THX AAA 789, but since so many of these amps have been sold with the original Massdrop logo on them, I decided not to change the title of this thread.
 
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Mar 1, 2018 at 8:00 PM Post #3 of 2,607
Mar 2, 2018 at 1:46 PM Post #4 of 2,607
I was interested in this amp until I saw what the wait was going to be. The lead time for many of Massdrop's audiophile products is just waaaaaay too long IMO. I'm not willing to let them sit on my money for 8 months when there are plenty of other fish in the sea. Maybe I'll pick up one of these used next year if I'm still curious and can find one for sale. Meanwhile, onward and upward.
 
Mar 2, 2018 at 5:31 PM Post #6 of 2,607
The spec tend to indicate it's a balanced amp since the power doubles on the balanced out. But, someone in Massdrop discussion mentioned 789 is 788 with a boosted power to match the output of 888. According to the attached 788 is a stereo amp and 888 is a dual mono amp. I'm not sure what a stereo amp means, but someone else in MD discussion mentioned 788 is not a balanced amp - rather merely has a balanced out jack. I am wondering if 789 a true balanced amp or shall I wait until MD releases 888/889 next year?

Here is a link to 788 which was also introduced by the same OP.
https://www.head-fi.org/threads/monoprice-monolith-desktop-thx-amp-dac-24459-impressions-thread.860046/
https://www.monoprice.com/product?p_id=24459
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Mar 2, 2018 at 8:42 PM Post #7 of 2,607
The spec tend to indicate it's a balanced amp since the power doubles on the balanced out. But, someone in Massdrop discussion mentioned 789 is 788 with a boosted power to match the output of 888. According to the attached 788 is a stereo amp and 888 is a dual mono amp. I'm not sure what a stereo amp means, but someone else in MD discussion mentioned 788 is not a balanced amp - rather merely has a balanced out jack. I am wondering if 789 a true balanced amp or shall I wait until MD releases 888/889 next year?

Here is a link to 788 which was also introduced by the same OP.
https://www.head-fi.org/threads/monoprice-monolith-desktop-thx-amp-dac-24459-impressions-thread.860046/
https://www.monoprice.com/product?p_id=24459

The 788 is single ended only, so amps like the upcoming Monoprice Dac/amp which use it but claim to be balanced are faking it. According to the engineer who designed the AAA tech and this amp, the 789 is a hybrid of the 788 and 888 which is actually balanced. Based on his replies throughout the discussion on the Massdrop comments, I would say if you want to get the AAA tech for headphones, this amp is the best option you are likely to see. The 888 is probably going to be mostly limited to speaker amps.
 
Mar 2, 2018 at 11:16 PM Post #8 of 2,607
The 788 is single ended only, so amps like the upcoming Monoprice Dac/amp which use it but claim to be balanced are faking it. According to the engineer who designed the AAA tech and this amp, the 789 is a hybrid of the 788 and 888 which is actually balanced. Based on his replies throughout the discussion on the Massdrop comments, I would say if you want to get the AAA tech for headphones, this amp is the best option you are likely to see. The 888 is probably going to be mostly limited to speaker amps.
888 definitely has a headphone amp spec. However, I’m thinking of ordering 789 since who knows when 888 will be released.
 
Mar 2, 2018 at 11:36 PM Post #9 of 2,607
Based on Massdrop's specs for the 789, it looks like it actually is a fully-balanced design. The power from its balanced output quadruples (compared to its SE output) into 32,300 & 600 Ohm loads.
My best guess is that it uses two 788 stereo modules to create a fully-balanced circuit. :nerd:
 
Mar 3, 2018 at 1:35 AM Post #10 of 2,607
Based on Massdrop's specs for the 789, it looks like it actually is a fully-balanced design. The power from its balanced output quadruples (compared to its SE output) into 32,300 & 600 Ohm loads.
My best guess is that it uses two 788 stereo modules to create a fully-balanced circuit. :nerd:
That's a bit unclear.

AndrewMason (THX Ltd. Analog & Power Engineering Expert):
Compared to the Massdrop 789, the Monoprice 788:
-uses the same AAA technology
-788 has less output current/voltage/power
-788 no true balanced output (has XLR-4, but it's only driven single-ended)
-788 includes a DAC selected by the Monoprice team.

So it depends on what you're looking for.
(Source)
There are some very expensive, very nice opamps in there! Supporting truly balanced signal pathway throughout would shoot the cost through the roof, for negligible improvement. See Bruno Putzeys' EDN article on why having truly balanced signal path isn't necessary. "Symmetry is useless". " Differential transmission of audio doesn't mean you need to make a symmetrical voltage " https://www.edn.com/design/consumer/4429968/2/The-G-word--How-to-get-your-audio-off-the-ground
(Source)

It certainly seems like it produces fully balanced output (signal on one conductor, inverse signal on the other) regardless of the input, while the Monoprice runs the 4-pin XLR single ended (signal on one conductor, nothing on the the other). But the amp itself does not seem to be truly balanced end to end.
 
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Mar 3, 2018 at 1:46 PM Post #11 of 2,607



https://www.massdrop.com/buy/massdrop-x-thx-aaa-789-linear-amplifier

The Massdrop x THX AAA 789 is finally available to order! :grinning:

Unfortunately, and as per usual with Massdrop, it won't be shipping until Halloween! :dizzy_face:

Discuss!


Just as a small remark, difficult to discuss the "impressions" when no one has heard the actual amp, nor released any review. In the end, the device is there to allow users to listen (to the audio).
Discussing the specs. - now, that - I understand and it should be encouraged, as well as discussing the design.

The amp is offered att Massdrop at a very good price and it looks very promising.

I would be looking forward to read the review of the amp from someone who has demoed it extensively. Somehow, I don't think it would hurt the sales either.
 
Mar 3, 2018 at 7:38 PM Post #12 of 2,607
1. No DAC
2. External power supply
3. Made in China (guess)

I'll pass. Not sure what the point of 0.000007% THD when my headphones are 0.01% to 2% (HD 650); many other headphones are even worse. The Chord Mojo does the job just fine.
What DAC do you need to keep the combo in that THD range and who can hear the difference?
The price is good though - I have to say it's cheap.
 
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Mar 4, 2018 at 5:12 PM Post #13 of 2,607
I would also love to hear about the listening impressions of someone who has demoed the amp. There is a Head-Fi TV YouTube video associated with Cam Jam London in which it is suggested that listening impressions were forthcoming. I am unable to find anything of the sort. Has anyone critically listened to any version of a THX AAA headphone amp? The gentleman in that video said he was impressed with his initial listening. It seems to me that putting out a few demo units of any of the versions would be a good move on the part of THX, if they are indeed as good as it appears from the specifications and measurements. In my experience with different DACs, amplifiers and other components, I have found that a spec sheet is a good indicator of the technical quality of a component, but it is hardly a replacement for the impressions of a person who has heard the amp, as well as many others, and can thereby judge its merits. Has anyone done this?
 
Mar 4, 2018 at 5:33 PM Post #14 of 2,607
1. No DAC
2. External power supply
3. Made in China (guess)
This was my take away also. I mentioned the issue about the external power supply on Massdrop, and was told this should not even be a point of discussion.
OK Then !
 
Mar 4, 2018 at 7:15 PM Post #15 of 2,607
1. No DAC
2. External power supply
3. Made in China (guess)

4. How does it actually sound?
That’s the key one for me.

With respect to the other three points:

1. I’d rather use my own DAC that I like and have picked for myself rather than one picked for me that I have to pay for whether I like it or not.
2. This depends on how good a job they do with the external power supply. Also, it allows for an easier power supply upgrade if desired. I prefer to separate the power supply and circuit in my builds, so I see this as a good thing.
3. Probably a good guess.
 

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