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Monoprice Monolith THX 887 Balance Headphone Amp: New Champ?

T.J. Turner

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Gain 3 clips with 4V balanced output. This is actually mentioned in the manual IIRC. This doesn't happen with unbalanced, only with balanced input.

What headphone are you using that requires gain 3 though?! :)

Wait, you got a manual with yours!?

I tested mine at gain 3 using XLR inputs and output, and I get no distortion.
 

NemoReborn

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Gain 3 clips with 4V balanced output. This is actually mentioned in the manual IIRC. This doesn't happen with unbalanced, only with balanced input.

What headphone are you using that requires gain 3 though?! :)


i am using the dt1990 . they dsnt need gain 3 for sure , its just where is that distortion comming from and how come my friend is not experiencing this with his dx7s and T.J Turner either with his su-8 ...
 

NemoReborn

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Is there any other source connected to your abaj d5 that is turned off? If so turn it on.

im not sure what u mean , the sabaj is connected via USB and xlr out to xlr in into the thx .. and the headphone into the SE 1/4 from the thx
 

T.J. Turner

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im not sure what u mean , the sabaj is connected via USB and xlr out to xlr in into the thx

The closest experience I've had is when using Schiit stuff. Like the Gungnir for example if I have it outputting to two devices and one device is turned off, distortion is heard in the other output. If all you have connected is the usb, then this is not the case for you.

At this point I'd try connecting a different DAC if possible, and see if the problem remains. There is also the possibility that you have a defected THX 887.
 

Hemi-Demon

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when i am using the sabaj d5 feeding the 887 with xlr , im getting distortion to my headphone at my regular listening volume ?? never experienced this when using RCA ... i actualy have to reduce the gain from 3 to 2 on the 887 and pushing the volume back to listening volume and the distortion is gone .... any clue !???

Have you tried the Beyer's on the balanced 4pin output? Have you switched your XLR cables? Maybe try rca input, and single ended output together. What amp were you using prior to the 887(through XLR out from the Sabaj) that did NOT exhibit this issue?

You should add more detail. I bet its the Sabaj output that is more likely

Gain 3 clips with 4V balanced output. This is actually mentioned in the manual IIRC. This doesn't happen with unbalanced, only with balanced input.

What headphone are you using that requires gain 3 though?! :)

@Veri

Can you scan the manual to pdf and upload it. It would certainly be appreciated
 
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Veri

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This is the same design as the massdrop THX amp, which takes maximum ~2.1V before clipping in gain III. If you feed it 4V over balanced, it will clip badly in highest gain. Only with a 2V DAC you can use all three gain modes to maximum volume. However, very few headphones would need gain three at high volume...

I would expect the product spec sheet or manual would mention the maximum input voltage :oops:
 

Celty

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Apparently my SU-8 is stuck in Hong Kong in DHL Hell. Meanwhile I anticipate the 887 amp to arrive next week. As others have not gotten a manual with their 887, I am wondering if there would be any problem feeding the amp from the RCA outputs on my Xonar Essence STX sound card in the interim?
 

T.J. Turner

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The 887 does not come with any printed or downloadable documentation.
Assuming the specs are the same. There is some information from the 789 manual.

  • When using a DAC or source with <2.1 V output, any gain position may be used.
  • When using a DAC or source with >2.1 V output, only use low and medium gain positions, or else the 789 preamp may clip internally
The maximum DAC or Source voltage is 7 Vrms. (+19 dBu) to avoid the 789 preamp clipping.
If using a higher voltage DAC or source, apply a small amount of attenuation (e.g. in the media player) to reduce the maximum source voltage to 7 V / +19 dBu maximum.
 
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Celty

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The 887 does not come with any printed or downloadable documentation.
Assuming the specs are the same. There is some information from the 789 manual.

  • When using a DAC or source with <2.1 V output, any gain position may be used.
  • When using a DAC or source with >2.1 V output, only use low and medium gain positions, or else the 789 preamp may clip internally
Hmm... from the Essence STX manual:
Output/Input Full-Scale Voltage - 2 Vrms (5.65 Vp-p)

Hopefully, I should be good to go, thanks :)
 

T.J. Turner

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Hmm... from the Essence STX manual:
Output/Input Full-Scale Voltage - 2 Vrms (5.65 Vp-p)

Hopefully, I should be good to go, thanks :)

My experience with analog out from a PC is that it always carries noise with it. Also the analog input of the 789/887 does not have the 2.1V limitation that the XLR inputs have.
 

Celty

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My experience with analog out from a PC is that it always carries noise with it. Also the analog input of the 789/887 does not have the 2.1V limitation that the XLR inputs have.
Ahh OK, hopefully the RCA outputs from the STX sound card are cleaner than most, but it will be a temporary solution.
 
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NemoReborn

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This is the same design as the massdrop THX amp, which takes maximum ~2.1V before clipping in gain III. If you feed it 4V over balanced, it will clip badly in highest gain. Only with a 2V DAC you can use all three gain modes to maximum volume. However, very few headphones would need gain three at high volume...

I would expect the product spec sheet or manual would mention the maximum input voltage :oops:

Ok ... so if i understand well , from amirm’s review if the D5 , the xlr output send 4v and the rca 2v. So thats why i was able to use all gain in rca and not in xlr ?

any benefit being connected with xlr between the d5 and the 887 ???
 

T.J. Turner

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Ok ... so if i understand well , from amirm’s review if the D5 , the xlr output send 4v and the rca 2v. So thats why i was able to use all gain in rca and not in xlr ?

any benefit being connected with xlr between the d5 and the 887 ???


I don't know how to interpret a lot of the measurements. According to his analysis the SU-8 outputs 4V rms also. And I hear no distortion when I tested gain 3. The advantage of XLR give you an additional 6 dB gain and consistent quality over long cable runs.
 

NemoReborn

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I don't know how to interpret a lot of the measurements. According to his analysis the SU-8 outputs 4V rms also. And I hear no distortion when I tested gain 3. The advantage of XLR give you an additional 6 dB gain and consistent quality over long cable runs.

You tested it with Single ended headphone or xlr ?
 

NemoReborn

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Do i still benefit from the high watts output from the xlr front 4 pin , even if im running the setup rca from the dac ?
 

jruser

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Got my 887 today.

Hooked with XLR to Sabaj D5, listening to DT177x GO with a balanced cable. Had to listen with volume below 9 o'clock on gain 1. I put an ieMatch inline with the headphones to give me more space on the volume knob. Sounded fine without the ieMatch, but a small bump of the knob would cause drastic increase in volume.
 
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