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DenonFanboy
825
Feb 27, 2018
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I’m sorry, don’t get me wrong I do love Massdrop but all specs measured at 1% THD isn’t great.
DenonFanboy
825
Feb 27, 2018
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MotorradI’m just used to measurements that all other companies do and quite frankly don’t understand this standard :S
Bobthedespot
85
Feb 27, 2018
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Motorrad'"THD: -140 dB, 300 ohms, 100 mW"
I'd call this impressive.'
More likely B.S...
Never seen a credible spec taking with a useful standard that can place THD+N that low, largely due to a total lack of equipment capable of that kind of measurement.
More likely B.S...
Never seen a credible spec taking with a useful standard that can place THD+N that low, largely due to a total lack of equipment capable of that kind of measurement.
Motorrad
2898
Feb 27, 2018
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Bobthedespothaha. I've seen -140...the -143 is suspect, but from prototypes I have heard, I'd say it was possible. The architecture is not new and such low THD/N has been theorized for some time.
Bobthedespot
85
Feb 27, 2018
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MotorradBut never measured. Seriously, just name a single company that makes a signal analyzer that works that well.
And regarding the topology, unless higher-order distortions are controlled just as much as lower-order distortions, the THD spec will not be even remotely useful.
The topology that THX claims to use here is a high-efficiency dedicated low frequency design. If the website is factually accurate (doubtful in light of other incorrect statements on the site), then the current feedback will not manage higher order harmonics well at all, and the general sound will be similar to a saturated class-D amp.
And regarding the topology, unless higher-order distortions are controlled just as much as lower-order distortions, the THD spec will not be even remotely useful.
The topology that THX claims to use here is a high-efficiency dedicated low frequency design. If the website is factually accurate (doubtful in light of other incorrect statements on the site), then the current feedback will not manage higher order harmonics well at all, and the general sound will be similar to a saturated class-D amp.
Motorrad
2898
Feb 27, 2018
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BobthedespotNaming manufacturers of signal analyzers is really not my forte...maybe 20yrs ago. I would doubt you could count how many that measure that on one...finger.
I doubt it will be long before someone chimes in with the answer how they measured that...
"...and the general sound will be similar to a saturated class-D amp..." ...I was thinking that about a year ago when I heard the design discussed; it does not sound like that.
I'm very familiar -intimately even- with how similar topologies were implemented on sub amps, but this is not that.
BTW, which THX spec are you referring to?
Bobthedespot
85
Feb 27, 2018
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MotorradI'm only 3 years out of the industry, and I worked with totl Audio Precision, B&K, and Rhode/Schwartz equipment.
None of it even approached 140 dB, and the best I have ever seen was the LX800 prototype which could manage 138dB. Chris Straum is dead now, and there is a 0% chance he would ever work with THX.
Here is the spec with the reference design: https://www.triadsemi.com/wp-content/uploads/dlm_uploads/2016/12/triadsemi_tsthx88_productbrief.2016-12-19.pdf
None of it even approached 140 dB, and the best I have ever seen was the LX800 prototype which could manage 138dB. Chris Straum is dead now, and there is a 0% chance he would ever work with THX.
Here is the spec with the reference design: https://www.triadsemi.com/wp-content/uploads/dlm_uploads/2016/12/triadsemi_tsthx88_productbrief.2016-12-19.pdf
AndrewMason
558
THX Ltd. Analog & Power Engineering Expert
Feb 27, 2018
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CokemanBob: The APx555 is new on the scene, and is a wonderful instrument. And yes, AAA completely avoids generating the higher-order harmonics at all listening levels, without resorting to a space-heater Class A architecture. Quiescent consumption on the unit is ~3 Watts.
APx555 Loopback @ 5.5 Vrms, 1 kHz
Massdrop THX AAA 789 @ 5.5 Vrms, 1 kHz, 300 Ω (100 mW per Ch):
Massdrop THX AAA 789 @ 0.55 Vrms, 1 kHz, 300 Ω (1 mW per Ch):
APx555 Loopback @ 5.5 Vrms, 1 kHz
Massdrop THX AAA 789 @ 5.5 Vrms, 1 kHz, 300 Ω (100 mW per Ch):
Massdrop THX AAA 789 @ 0.55 Vrms, 1 kHz, 300 Ω (1 mW per Ch):
Bobthedespot
85
Feb 27, 2018
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AndrewMasonHoly crap
Edit: This is really interesting, can you run this with a set of 10-20 ohm cans or iems?
Edit: This is really interesting, can you run this with a set of 10-20 ohm cans or iems?
CEE_TEE
3480
Feb 27, 2018
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DenonFanboyTHD:
-143 dB 300 Ω@ 1 mW = 0.000007%
-140 dB 300 Ω @ 100 mW = 0.000010%
-125 dB 32 Ω @ 1 mW = 0.000056%
-123 dB 32 Ω @ 100 mW = 0.000071%
-120 dB 16 Ω @ 1 mW = 0.000100%
-118 dB 16 Ω @ 100 mW = 0.000126%
IMD:
-123 dBSMPTE 70 Hz + 70 kHz, 300 Ω = 0.000071%
-124 dBDFD 18 kHz + 19 kHz, 300 Ω = 0.000063%
Crosstalk:
-127 dB, 300 Ω = 0.000045%
DenonFanboy
825
Feb 27, 2018
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CEE_TEEOk that’s dead quiet, I think u will hear a ghost b4 u hear distortion on this amp.
Bobthedespot
85
Feb 27, 2018
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DenonFanboyDepends if Earl Geddes was correct in his theories of psychoacoustics...
I think I'll buy one just to put on my analyzer, to see if the hype is real.
The crazy good specs for this headphone amp are @ zero gain... it remains to be seen what happens in different scenarios.
I think I'll buy one just to put on my analyzer, to see if the hype is real.
The crazy good specs for this headphone amp are @ zero gain... it remains to be seen what happens in different scenarios.
Rajb
2
Dec 30, 2018
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AndrewMasonHi Andrew. Just wondering if you know when the THX AAA 789 will drop again? Thanks.
AndrewMason
558
THX Ltd. Analog & Power Engineering Expert
Dec 31, 2018
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rastus
1391
Sep 28, 2019
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AndrewMasonAndrew, Is the drop Airist R-2R DAC well matched to the THX789? A statement that it was “too hot”; is 2.5V on the high side for the THX?
(Edited)
rastus
1391
Oct 3, 2019
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LisasonictowerThanks, knew, but hoping for a response also from the maker, to counter a “hot” accusation in another thread.
Lisasonictower
666
Oct 3, 2019
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rastusIf we were to go by the tech specs then you would say do not use gain 3 with a input signal above 2.1v
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