• 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.

Monoprice Monolith THX 887 Balance Headphone Amp: New Champ?

Jimmy

Active Member
Joined
Jun 20, 2018
Messages
158
Likes
63
I guess that monoprice just OEMs these (and many other of their products), the 887 seems to be mostly the same as the 789, but with lower height case, different knobs, no vent holes?, and when internal pictures appear we'll see the rest.

Anyway almost every brand screw things up sometimes, I understand what you say, but you'll eventually get burned at some point even with big names, the important thing is how they react when these things happen.

Thanks to Amir for the test results and review!

As a Massdrop 789 owner, the slight improvements over their unit are impressive, but for certain inaudible.

As a former Monolith portable DAC\amp owner, I promised that I'd never trust my ears to their gear again, and I stand by that. Caveat emptor. My headphones are too expensive and my ears too precious for me to readily trust their gear. Despite the fantastic test results, I cannot help but feel that this company, at some level, failed me. For those few niggling decibels, I'm going to stick with companies that don't ship gear that may or may not blow eardrums into kingdom come.

In all earnestness, I hope no one gets the eardrum punishment from this amp that I got in the past. I don't trust them.
 
Last edited:

JohnYang1997

Major Contributor
Joined
Dec 28, 2018
Messages
1,344
Likes
630
I guess that monoprice is just an OEM for these (and many other of their products), the 887 seems to be mostly the same as the 789, but with lower height case, different knobs, no vent holes?, and when internal pictures appear we'll see the rest.

Anyway almost every brand screw things up sometimes, I understand what you say, but you'll eventually get burned at some point even with big names, the important thing is how they react when these things happen.
I think you meant the other way around? Thx being the oem and monoprice is just another dealer and branding.
 

JohnYang1997

Major Contributor
Joined
Dec 28, 2018
Messages
1,344
Likes
630
Can you explain why?
The difference is not even small. If the same circuits shows this much difference then the whole idea of using ic is falling apart. Not only distortion and noise performance can't be assured, even stability will likely to suffer. The variation in the components that are critical to the noise performance shouldn't vary much. Usually 0.1uV is maximum that I measure, assuming no drastic change in power supply noise, purely the noise from the components. I think this time is due to redesign of the gain stage. And could possibly be the resistors values in the output stage.
 

JohnYang1997

Major Contributor
Joined
Dec 28, 2018
Messages
1,344
Likes
630
I think I'll put together my findings a bit better.
According to massdrop page of thx789 the noise is 1uV when volume is zero. Meaning the noise is purely in the output stage.
According to the monoprice page, the noise of 789 is considerably higher than the spec on the massdrop page. And this performance is almost the same as what amir measured, amir doesn't vary the volume control when measuring. So the noise performance is degraded by the stuff before volume control, meaning could be gain stage and input buffer(also summing of differential inputs).
The 887 performance on monoprice is considerably better than 789, now we assume volume control at max(no noise contribution from pot but purely the stuff before the volume control). So basically it's almost certain the change is due to the redesign of gain stage.

Side note 3db is 1.4 times, it requires the two in parallel of entire circuit or decrease of gain or resistor value to make this much difference. Component variation that contributes noise is mostly at 0.2db range.
 

Jimmy

Active Member
Joined
Jun 20, 2018
Messages
158
Likes
63
The term OEM can be used in several ways, youre right, but it can just mean the outsourcing process. I edited the post anyway.

I think you meant the other way around? Thx being the oem and monoprice is just another dealer and branding.

I think you meant the other way around? Thx being the oem and monoprice is just another dealer and branding.
 
Joined
Nov 6, 2018
Messages
75
Likes
55
My Drop THX 789 is on the delivery truck. I appreciate both Amir's testing excellence and the narrow horserace at 117 vs. 119 db. Good to have a unit that doesn't require such an uncertain delivery schedule. No buyer's remorse on my part as I am absolutely certain that I can't perceive distortion differences at that low level.

Its like Porsche came out with a 911 model with 6 more horsepower. Ok, bravo for the new owners, but that doesn't obviate the excellence of the prior vehicles.
More like the difference between the Bugatti Veyron and the Bugatti Chiron.
 
Joined
Nov 6, 2018
Messages
75
Likes
55
If nothing else, the Monolith brings some competition. Maybe on price too. Hopefully they'll have a sale during the holidays. And other manufacturers should take notice. Put up your best engineering at a competitive price.
Now if we could just get these people making power amplifiers.
 

amirm

Founder/Admin
Staff Member
CFO (Chief Fun Officer)
Joined
Feb 13, 2016
Messages
20,583
Likes
25,363
Location
Seattle Area
What is the level of detail of this design? Schematics? BOM? Layout?
All secret until someone buys a production unit and performs a tear down. I can't do it with mine.
 

Music1969

Addicted to Fun and Learning
Joined
Feb 19, 2018
Messages
567
Likes
152
It's a near clone so either he or someone else took the 789 made minor tweaks and out came the 887 presumably
It's the these tweaks you mention, which I'd like to know if Andrew was involved... tagged him, so let's wait for his reply...
 
Top Bottom