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Review and Measurements of Monoprice THX Desktop DAC & Amp

AndrewMason

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#42
I don't want to call it thx technology which there is no sign for it to be an innovative technology. Just well engineered circuit using off the shelf parts.
Incorrect. AAA is innovative, with multiple patents on its unique innovative architecture (inductorless feed-forward plus feed-back) that cancels output stage noise and distortion - the dominant source in most amplifiers.

The fact that the Monoprice DAC-AMP and the 789 both have lower THD+N than their output stage chips should be your first clue that AAA is working.

Your simplistic analysis applied to a Mercedes-Benz would conclude that it's made of plastic and steel, therefore just well-engineered but nothing innovative therein. In that case, maybe they should fire their entire IP department.


(They should have used tpa6120 in a composite amplifier configuration which is going to be even better than thx 789)
With AAA, there's no distortion or noise penalty from using output stage chips that other competitors cannot. So we generally choose ones with higher peak output current capability among other considerations. Using this approach, we provide AAA customers with best of both worlds: high output power, and low THD+N.
 

JohnYang1997

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#43
Incorrect. AAA is innovative, with multiple patents on its unique innovative architecture (inductorless feed-forward plus feed-back) that cancels output stage noise and distortion - the dominant source in most amplifiers.

The fact that the Monoprice DAC-AMP and the 789 both have lower THD+N than their output stage chips should be your first clue that AAA is working.

Your simplistic analysis applied to a Mercedes-Benz would conclude that it's made of plastic and steel, therefore just well-engineered but nothing innovative therein. In that case, maybe they should fire their entire IP department.




With AAA, there's no distortion or noise penalty from using output stage chips that other competitors cannot. So we generally choose ones with higher peak output current capability among other considerations. Using this approach, we provide AAA customers with best of both worlds: high output power, and low THD+N.
The last bit, not true.
0.6uv20-20khz noise, 0.00003%thd under 16ohm load, 2W output with tpa6120a2 composite amplifier. Basically a little bit better than thx 789 but can run with batteries. If you guys can make some of those. It would be fun. 788 is ad8397 which has high output current but not very good with high frequency distortion under significant load. 789 is pretty impressive but +-12V is not ideal(balance output can save this tho).
 

JohnYang1997

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#44
Incorrect. AAA is innovative, with multiple patents on its unique innovative architecture (inductorless feed-forward plus feed-back) that cancels output stage noise and distortion - the dominant source in most amplifiers.

The fact that the Monoprice DAC-AMP and the 789 both have lower THD+N than their output stage chips should be your first clue that AAA is working.

Your simplistic analysis applied to a Mercedes-Benz would conclude that it's made of plastic and steel, therefore just well-engineered but nothing innovative therein. In that case, maybe they should fire their entire IP department.




With AAA, there's no distortion or noise penalty from using output stage chips that other competitors cannot. So we generally choose ones with higher peak output current capability among other considerations. Using this approach, we provide AAA customers with best of both worlds: high output power, and low THD+N.
Then, about patents, there is only one patent on thx site. All the different ones are actually same inside. And there is no feedforward circuitry (at least I can understand).
Also bith 788 789 888 use off the shelf ics. I don't see how you guys can make feedforward circuit like that. Or is the feedforward is different.
 

AndrewMason

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#45
The last bit, not true.
0.6uv20-20khz noise, 0.00003%thd under 16ohm load, 2W output with tpa6120a2 composite amplifier. Basically a little bit better than thx 789 but can run with batteries. If you guys can make some of those. It would be fun. 788 is ad8397 which has high output current but not very good with high frequency distortion under significant load. 789 is pretty impressive but +-12V is not ideal(balance output can save this tho).
It'll remain true until you become a competitor ;)
 

AndrewMason

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#46
Then, about patents, there is only one patent on thx site. All the different ones are actually same inside. And there is no feedforward circuitry (at least I can understand).
Also bith 788 789 888 use off the shelf ics. I don't see how you guys can make feedforward circuit like that. Or is the feedforward is different.
 

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Veri

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#48
Incorrect. AAA is innovative, with multiple patents on its unique innovative architecture (inductorless feed-forward plus feed-back) that cancels output stage noise and distortion - the dominant source in most amplifiers.

The fact that the Monoprice DAC-AMP and the 789 both have lower THD+N than their output stage chips should be your first clue that AAA is working.

Your simplistic analysis applied to a Mercedes-Benz would conclude that it's made of plastic and steel, therefore just well-engineered but nothing innovative therein. In that case, maybe they should fire their entire IP department.




With AAA, there's no distortion or noise penalty from using output stage chips that other competitors cannot. So we generally choose ones with higher peak output current capability among other considerations. Using this approach, we provide AAA customers with best of both worlds: high output power, and low THD+N.
Thanks for clarifying Andrew ;) I love the sound of my 789, for sure.
 

Jimster480

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#49
Incorrect. AAA is innovative, with multiple patents on its unique innovative architecture (inductorless feed-forward plus feed-back) that cancels output stage noise and distortion - the dominant source in most amplifiers.

The fact that the Monoprice DAC-AMP and the 789 both have lower THD+N than their output stage chips should be your first clue that AAA is working.

Your simplistic analysis applied to a Mercedes-Benz would conclude that it's made of plastic and steel, therefore just well-engineered but nothing innovative therein. In that case, maybe they should fire their entire IP department.




With AAA, there's no distortion or noise penalty from using output stage chips that other competitors cannot. So we generally choose ones with higher peak output current capability among other considerations. Using this approach, we provide AAA customers with best of both worlds: high output power, and low THD+N.
Well I personally love the technology as I use my THX AAA 789 every day! Its truely the headphone amp that I was always looking for. While it doesn't match my DX7 at all; the performance is nothing short of stellar and its provided me probably 600 hours of listening satisfaction so far :)
 

solderdude

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#50
I love the sound of my 789, for sure.
How can one love what is not there ... I thought the 789 has no sound of its own ... it is audibly transparent :p :D
 

Jimster480

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#51
How can one love what is not there ... I thought the 789 has no sound of its own ... it is audibly transparent :p:D
That's what is so beautiful about it :)
Its Musical bliss! There is no distortion to speak of; just the music as it was recorded!
 

Veri

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#52
How can one love what is not there ... I thought the 789 has no sound of its own ... it is audibly transparent :p:D
You kid but seriously, when I plug into the headphone out of my Aune DAC it sounds more 'lively' due to the harmonic distortion and impedance fuckery and what not. The THX sounds almost "laid-back" in comparison with its zero impedance out and excellently low distortion characteristics :)

It's almost like a wire with gain!! (I'm thinking that would not sell well as marketing one-liner lol)
 
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#53
I have a rule in purchasing things in general: if you can't decide, buy the cheapest. :) That would be D10. It is so cheap that if you want to get something else in the future, it won't be a big deal. I love the display on it and it can act as USB to S/PDIF converter. Note however that its only input is USB though.
After thinking it over I decided on the SMSL SU-8 just for future proofing as it has balanced outputs.

I see you mention issues with low level linearity over the unbalanced connection on the SMSL SU-8, would this be audible when using it with the JDS LABS ATOM?

I have been looking for an headphone amp with balanced input & output but other than the THX 789 is there any others you would recommend in the THX 789 price range or can nothing come close to it for the money?
 
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#54
Thank you for these tests Amir! Are you going to run more tests using the USB input? Maybe others have mentioned it and I missed it but the analog inputs are indeed digitized. That is why it can apply the DSP and DIrac to the analog inputs as well.
 
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#55
The unit tested was mine. I noticed audible noise floor hissing only when I used Campfire Audio (Orion, Andromeda, Solaris), BGVP DM6, and other super high sensitivity IEMs using a balanced connection (2.5mm to XLR). There was noticeable hiss on that. Otherwise, using every other headphone and less sensitive IEM I owned, noise floor was not an issue. For reference, I used it with Senn HD58X and 6XX, AKG M220, Focal Elex/Elegia, various Audeze headphones, and Hifiman HE560 without noise issues.
Hi,

This is exactly what happens to me, but grounding the case to Earth plug wihthin the EU plug solve this issue. Now there is Zero noise with sensitive IEMS.

I just take the earth cable from the EU plug and using an adaptor with the cable on it solve the issue. On one side is just a "banana" plug to the case with a small drill.

I know it could be more fashion, but from tech point of view problem solved!

Regards,

Manuel.
 

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Veri

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#56
Hi,

This is exactly what happens to me, but grounding the case to Earth plug wihthin the EU plug solve this issue. Now there is Zero noise with sensitive IEMS.

I just take the earth cable from the EU plug and using an adaptor with the cable on it solve the issue. On one side is just a "banana" plug to the case with a small drill.

I know it could be more fashion, but from tech point of view problem solved!

Regards,

Manuel.
Genius!
 
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#57
Hi,

This is exactly what happens to me, but grounding the case to Earth plug wihthin the EU plug solve this issue. Now there is Zero noise with sensitive IEMS.

I just take the earth cable from the EU plug and using an adaptor with the cable on it solve the issue. On one side is just a "banana" plug to the case with a small drill.

I know it could be more fashion, but from tech point of view problem solved!

Regards,

Manuel.
Thanks for this idea. I'll have to look into it when I get the unit back.
 
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#58
Yes (as is the massdrop THX). You can go with Topping D10, Schiit Modi 3, Topping D50 (matches its looks well), or SMSL SU-8.
Curious why you don't include a Khadas Tone Board in this list? It falls into a higher tier in the SINAD chart and is in the same price range- even including cost of a pre-fab case.
 
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Veri

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#59
Curious why you don't include a Khadas Tone Board in this list? It falls into a higher tier in the SINAD chart and is in the same price range- even including cost of a pre-fab case.
Probably because of its lack of a case :) not everyone is into the (admittedly reasonable) diy aspect of it.
 
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#60
Amir,

Is it possible for you to have the - Power versus Distortion using 300 OHM load - with USB Input for Balaced Output vs Unbalanced ? (Just if you did not return the unit to AntDroid -thanks by the way!-) and of course than to Amir for the amazin job!.

I guess should be similar to the one you presented on XLR Input, but I just wnat to confirm if noise issues are more related to Input or to Output... This would be great as we could compare just the Unbalance vs Balanced outputs just with the same inputs.

Regards,

Manuel.
 
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