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Monoprice Monolith THX 887 Balance Headphone Amp: New Champ?

JohnYang1997

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Question regarding the 887 amp. Is it ok to uses the 6.5 and 3.5 mm SE output at same time ??? Can it broke anything ?

im connected to the 1/4 inche with my dt1990 but i my gf wanna listen to her x2hr using the 3.5mm output at same time ...

I know gain should be a problem but we will figure a middle volume for both of us.

im just scared to plug both at same time and something would go boom
Short answer: No you won't break anything.

Realistic answer: as both of your headphones are open back you are likely to hear a bit of sound bleed from the other pair not being listened. It's probably not realistic. But it won't break anything.
 

YSC

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Here's actual pictures of the internals. This is the EXACT layout as the THX 789 with the exception of using OPamp 1612A instead of 1602A. The power supply is even the exact same and from the same manufacturer.

*edit* from what I could see, clarified below additional upgrades were done by manufacturer.

View attachment 39404View attachment 39405View attachment 39406View attachment 39407
A major drawback to me is they don't even use an ALPS blue... I would pay $100 more for a stepped atteunator but sadly the quality volume control for a STOA amp is missing in these THX offerings
 

Celty

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A major drawback to me is they don't even use an ALPS blue... I would pay $100 more for a stepped atteunator but sadly the quality volume control for a STOA amp is missing in these THX offerings
It is a non-issue to me. Just depends on your total chain and control preferences. In my case I want to control volume through my DAC's remote anyway. I just set the amp volume to about 2:00 O'clock with the appropriate gain setting of 1,2, or 3 depending on the headphones being used, and bang, it is perfect.
 

YSC

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It is a non-issue to me. Just depends on your total chain and control preferences. In my case I want to control volume through my DAC's remote anyway. I just set the amp volume to about 2:00 O'clock with the appropriate gain setting of 1,2, or 3 depending on the headphones being used, and bang, it is perfect.
in case you have a volume control on your dac it's fine, for me using the holo spring 2 which don't have volume control I do enjoy having a quality pot or attenuator, hope something based on the excellent design with a better pot available in the future
 

Celty

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in case you have a volume control on your dac it's fine, for me using the holo spring 2 which don't have volume control I do enjoy having a quality pot or attenuator, hope something based on the excellent design with a better pot available in the future
Ah that makes sense, I knew what amp I was going to acquire, so luckily that let me me plan on what DAC features I wanted, including volume control to go with it.
 

Pillars

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A major drawback to me is they don't even use an ALPS blue... I would pay $100 more for a stepped atteunator but sadly the quality volume control for a STOA amp is missing in these THX offerings
I've considered it but the pot in this unit is of the smaller pin layout variety and I'd have to do some heavy modding as there are critical components in the way making a bigger pot not possible without major headaches. I've done pot swaps before (namely the Questyle CMA400i's pot is terrible, I replaced it with an Alps RK27) but this one does not look doable. On the Questyle all I had to do was move some vregs to the bottom to clear room and lay the rear pins of the RK27 forward and pad solder them well to the PCB. On top of machining the front panel to make room as well. The 887 has a pretty sizable signal relay in the way that pumps the brakes on this. On the bright side I don't really have any issues with the pot. It seems to perform fine enough for me not to consider replacement.
 
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netcipher

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Not quite, since there's no such thing as a 789 or a 887 in there. They are tweaked versions made for drop/monoprice.
They all have very similar circuit design. And all are based on THX patents. For me, these are variations of one amplifier.
 

JohnYang1997

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They all have very similar circuit design. And all are based on THX patents. For me, these are variations of one amplifier.
They lack a very critical part of the AAA circuitry which is the power supply. They perform well but they are really a half ass design. The patent is just a smoke, the actual performance is mostly not contributed by the design in patent.
 

netcipher

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They lack a very critical part of the AAA circuitry which is the power supply. They perform well but they are really a half ass design. The patent is just a smoke, the actual performance is mostly not contributed by the design in patent.
There is no doubt that the power system affects the parameters of the amplifier. But using standard approaches to the implementation of the power system, you can achieve any practically necessary parameters. The THX patents clearly define the composite amplifier and feedback design, which reduces non-linear distortion without the need for an increase in loop gain.
 

Ntrax

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IMG_20200123_015858__01.jpg
 

Ntrax

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Isn't that super loud? Balanced 4V DAC, and balanced output being double as loud as SE output. It honestly surprises me you are at gain 2.
Not at all my friend..I can go up to 10 to 11.. depending on songs and time. Usually early morning I'll go for 9..then later night I'll go higher.
 

Veri

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Not at all my friend..I can go up to 10 to 11.. depending on songs and time. Usually early morning I'll go for 9..then later night I'll go higher.
Volume on PC/source side also at 100%?? I guess those planars are real suckers for power, then!
 

Ntrax

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Volume on PC/source side also at 100%?? I guess those planars are real suckers for power, then!
Yeah both at 100%> then just adjust from the amp volume. This planar are not to be said power hungry, but they need the volt to make them what they supposed to be. Every threshold from the volume makes their potential multiply. So once you hear the goodness you can't unhear them.. so low volume for this cans are a no No.
 
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