[owner's thread] Monoprice Monolith THX AAA 887 headphone amp

[rozel]

Thanks @cosmom3 . Just seen your reply. Yes connecting the XLR inputs and outputs from the DAC to the Amp will definately provide a balanced output from the Amp. But to get the additional power through my headphones, which is the whole point of doing this, I think I would need to implement a "Balance Conversion" to my 'phones first - there's a guide to doing this online. But what I'd like to know before undertaking this is: -

1. Would there be any noticable difference connecting the DAC and Amp together via XLR balanced cables and then feeding the 'phones with a standard cable from one of the two output jacks on the front of the Amp?

2. Would there be any noticable difference connecting the DAC and Amp as above and then connecting to the 'phones with a 3.5mm 1/8" TRS Male & 6.3mm 1/4" adapter to 4-pin XLR Balanced Female headphone Audio Adapter cable? I've read that this could bugger things up as I'd be effectively shorting the Grounds of both channels. I would also like some information about this please too, if possible.

I hope someone could answer for me - the conversion of the 'phones appears to right on the cusp of my electronic skills and am a little frightened to proceed unless I know the answers to the above first, to give me the required motivation, if you know what I'm saying.

The amp has just this minute been delivered so will be connecting up shortly - frightened to use the connector(s) in 2. above until I hear back.

Thank you

 

[Jimbob54]

Thanks @cosmom3 . Just seen your reply. Yes connecting the XLR inputs and outputs from the DAC to the Amp will definately provide a balanced output from the Amp. But to get the additional power through my headphones, which is the whole point of doing this, I think I would need to implement a "Balance Conversion" to my 'phones first - there's a guide to doing this online. But what I'd like to know before undertaking this is: -

1. Would there be any noticable difference connecting the DAC and Amp together via XLR balanced cables and then feeding the 'phones with a standard cable from one of the two output jacks on the front of the Amp?

2. Would there be any noticable difference connecting the DAC and Amp as above and then connecting to the 'phones with a 3.5mm 1/8" TRS Male & 6.3mm 1/4" adapter to 4-pin XLR Balanced Female headphone Audio Adapter cable? I've read that this could bugger things up as I'd be effectively shorting the Grounds of both channels. I would also like some information about this please too, if possible.

I hope someone could answer for me - the conversion of the 'phones appears to right on the cusp of my electronic skills and am a little frightened to proceed unless I know the answers to the above first, to give me the required motivation, if you know what I'm saying.

The amp has just this minute been delivered so will be connecting up shortly - frightened to use the connector(s) in 2. above until I hear back.

Thank you

1. If there is no interference/ RF noise from the RCA connection (which balanced connection might eliminate) then no.

2. Dont try and connect singled ended wired 'phones to a balanced amp socket. Wont go well. I would suggest converting to balanced properly wont bring benefits either, there is bags of power in single ended form from the THX into the M50. Guessing you arent arent high gain and full volume with them?

By all means buy some cheap XLR interconnects and try it connecting the dac to amp but the only difference will be you will use less volume on the knob when connected by XLR than by RCA. No sonic improvements unless it eliminates obvious noise.

 

[rozel]

1. If there is no interference/ RF noise from the RCA connection (which balanced connection might eliminate) then no.

2. Dont try and connect singled ended wired 'phones to a balanced amp socket. Wont go well. I would suggest converting to balanced properly wont bring benefits either, there is bags of power in single ended form from the THX into the M50. Guessing you arent arent high gain and full volume with them?

By all means buy some cheap XLR interconnects and try it connecting the dac to amp but the only difference will be you will use less volume on the knob when connected by XLR than by RCA. No sonic improvements unless it eliminates obvious noise.

Thank you so much - I'll connect the 'phones normally but will connect the Dac and Amp using the Balanced XLR cables I've just purchased rather than sending back - cheers

 

[cosmox]

My unit has different sound on high gain when i plug the same heaphones to 6.3mm jack and when using 3,5 mm jack. The volume is the same level but there is a difference in sound positioning - 6,3m plays wider, i'd say too wide even. It's seems weird to me. Did you notice such thing in your units too?

 

[e to the ric]

Hey hey, I just got this amp a week ago and am trying to figure out how to switch the output between my speakers & headphones. I currently have my speakers connected to the RCA pass and have my mac mini connected to the RCA input. I was hoping that the output would switch to the headphones when i have it plugged in but it doesn't and it seems the only way to get my headphones to play is to unplug the speakers via the RCA pass. Am I doing something wrong or does the bypass always have first priority?

 

[Jimbob54]

Hey hey, I just got this amp a week ago and am trying to figure out how to switch the output between my speakers & headphones. I currently have my speakers connected to the RCA pass and have my mac mini connected to the RCA input. I was hoping that the output would switch to the headphones when i have it plugged in but it doesn't and it seems the only way to get my headphones to play is to unplug the speakers via the RCA pass. Am I doing something wrong or does the bypass always have first priority?

Something isn't right there. The rca pass is constantly on regardless of headphones connected. Do the question is why no sound from headphones?
Have you toggled the input select button from xlr in to rca?

 

[e to the ric]

Something isn't right there. The rca pass is constantly on regardless of headphones connected. Do the question is why no sound from headphones?
Have you toggled the input select button from xlr in to rca?

I've tried the input button but it has no effect. Sound is always coming from the speakers, even when the amp is turned off. Do I have a faulty unit? Is it designed to be this way? I can't find any documentation on anything... Also headphones is connected via 3.5mm if that makes any difference

 

[Jimbob54]

I've tried the input button but it has no effect. Sound is always coming from the speakers, even when the amp is turned off. Do I have a faulty unit? Is it designed to be this way? I can't find any documentation on anything... Also headphones is connected via 3.5mm if that makes any difference

It's a pass thru, it's always on. That bit is fine (or at least working as intended). What I don't like is that your headphones get no sound. Or are they perhaps just drowned out by the speakers?

In current config only turning the speakers off will stop them playing.

 

[e to the ric]

It's a pass thru, it's always on. That bit is fine (or at least working as intended). What I don't like is that your headphones get no sound. Or are they perhaps just drowned out by the speakers?

In current config only turning the speakers off will stop them playing.

I did not know that the pass thru is always on so my headphones were getting drowned out. I tried turning off my speakers before but it didn't work (probably had the wrong input or maybe forgot to turn up the gain/volume?) but I just tried it again and it's working. Thanks for the help! I think I get what's going on now.

 

[Jimbob54]

I did not know that the pass thru is always on so my headphones were getting drowned out. I tried turning off my speakers before but it didn't work (probably had the wrong input or maybe forgot to turn up the gain/volume?) but I just tried it again and it's working. Thanks for the help! I think I get what's going on now.

Glad you are sorted, even if that's not what you wanted. If you want to run headphone and active speakers from the same source (mac) you still can. You just need an rca switch box (not expensive) and a couple more leads. Run the 3.5 to rca cable into switch box input. Run rca to rca from switch box output 1 to headamp and another set to speakers and use the switcher. Amazon will have for 20 to 30 $

 

[Rottmannash]

Something isn't right there. The rca pass is constantly on regardless of headphones connected. Do the question is why no sound from headphones?
Have you toggled the input select button from xlr in to rca?

The passthrough is active even when the amp is off. I use it that way w/ powered computer speakers as well as w/ a variety of HP's.

 

[Jimbob54]

The passthrough is active even when the amp is off. I use it that way w/ powered computer speakers as well as w/ a variety of HP's.

I know. Don't think the OP did though. All sorted now though.

 

[Rottmannash]

I know. Don't think the OP did though. All sorted now though.

sorry-was reading way after the fact and answered before reading further where you gave him the info. I need to read the entire thread before commenting.

 

[ardilla]

Hi, just got myself over of these and consider me impressed. Great sounding unit, especially for the price. Unfortunately I damaged the DC cable and ordered a PSU off AliExpress 24V, 50VA

https://a.aliexpress.com/_m0uFNrk

Anyone knows what is the dimensions for the Monolith THX 887 of the DC barrel plug?

5.5mm*2.5mm or 5.5mm*2.1mm ?? Or something else?

 

[ardilla]

Hi, just got myself over of these and consider me impressed. Great sounding unit, especially for the price. Unfortunately I damaged the DC cable and ordered a PSU off AliExpress 24V, 50VA

https://a.aliexpress.com/_m0uFNrk

Anyone knows what is the dimensions for the Monolith THX 887 of the DC barrel plug?

5.5mm*2.5mm or 5.5mm*2.1mm ?? Or something else?

I'll answer myself, it's a 5.5mm*2.1mm DC cable plug for the Monolith THX AAA 887

 

[ardilla]

Another thing.

My gain switch does not work anymore it just doesn't do anything? Anyone had this experience?

 

[rcstevensonaz]

What has been the experience with RMA replacement units — and any changes in the quality of the current model vs. three years ago? My volume knob has recently developed a lot of static, and I am still (just barely) within the 3 year warranty period with purchase date in Nov 2020.

 

[Moderate Dionysianism]

What has been the experience with RMA replacement units — and any changes in the quality of the current model vs. three years ago? My volume knob has recently developed a lot of static, and I am still (just barely) within the 3 year warranty period with purchase date in Nov 2020.

Had the same issue in early 2022 (see post#14). No trouble with getting a replacement unit within the warranty period. But note that I had ordered from monoprice.eu, which is no more:

The replacement unit also developed the noise issue after <6 months of use, so I just opened it and cleaned the pot myself (also described in post#14). Has been working like a charm and dead quiet since then.

 

[rcstevensonaz]

Had the same issue in early 2022 (see post#14). No trouble with getting a replacement unit within the warranty period. But note that I had ordered from monoprice.eu, which is no more.

Running into issue that they have been out of stock since I filed for warranty in early November. The claim was approved... but still waiting for replacement .

 

[ardilla]

Running into issue that they have been out of stock since I filed for warranty in early November. The claim was approved... but still waiting for replacement .

I'm in the same position