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Review and Measurements of Massdrop THX AAA 789 Amp

raistlin65

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Asgard 3 is not class A, so sort of like a CFL to your LED bulb.
Okay. So upon further research, it appears it is Class A up to the first 500 mw at 32 ohms. So about half as much power usage in idle as the Asgard 2, but maybe a order of magnitude more than a low bias full class AB. I think I'll hold out.
 

raistlin65

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phoenixdogfan

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So I started plowing through the whole thread, and discovered this graph from Amir which shows the voltage and SINAD with 2V unbalanced input and single ended output

View attachment 102782

https://www.audiosciencereview.com/...sdrop-thx-aaa-789-amp.5001/page-4#post-111966

That's plenty of voltage output for my needs. Time to order!
I bought it over a year ago now. Some thing exceed it by 1-2 db of SINAD and a little more power, but, for all intents and purposes, this amp is perfect for any use case I could imagine.
 
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So I started plowing through the whole thread, and discovered this graph from Amir which shows the voltage and SINAD with 2V unbalanced input and single ended output

View attachment 102782

https://www.audiosciencereview.com/...sdrop-thx-aaa-789-amp.5001/page-4#post-111966

That's plenty of voltage output for my needs. Time to order!
I don't understand some things thing about max voltage, especially with those THX amps that has no findable specs;
Does the 6V max voltage level connected with 2V dac, are referred with normal gain in (1.0x gain, 0dB) output? Does it mean that with high gain in SE output (3.3x gain, +10dB) it will be 6V x 3.3= around 18V Maximium voltage? But i don't think this amp can reach 18V at maximum, there is very little info about, but i think i understand it is capable of max 11-12V (maybe at 300 ohm), not sure at all tho. 'Maximum Output Voltage, 11.5 Vrms into 300 Ohms', like Benchmark HPA4 THX amp. I have the 887 now but i used to have 789 before, they should share the same specifications.
Correct me if i'm wrong above, anyway... would be with balanced 4V dac's on balanced output with medium gain, double the maximum current? And the headphones most users will use would be 32ohm or lower, this what i will own at least, no chanches to detect if max output voltage would be higher around 32 ohm, vs 12V max at 300 ohm (Again, not sure about the max voltage spec)? Thanks in advance, hard to check online about..
 

Rottmannash

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I don't understand some things thing about max voltage, especially with those THX amps that has no findable specs;
Does the 6V max voltage level connected with 2V dac, are referred with normal gain in (1.0x gain, 0dB) output? Does it mean that with high gain in SE output (3.3x gain, +10dB) it will be 6V x 3.3= around 18V Maximium voltage? But i don't think this amp can reach 18V at maximum, there is very little info about, but i think i understand it is capable of max 11-12V (maybe at 300 ohm), not sure at all tho. 'Maximum Output Voltage, 11.5 Vrms into 300 Ohms', like Benchmark HPA4 THX amp. I have the 887 now but i used to have 789 before, they should share the same specifications.
Correct me if i'm wrong above, anyway... would be with balanced 4V dac's on balanced output with medium gain, double the maximum current? And the headphones most users will use would be 32ohm or lower, this what i will own at least, no chanches to detect if max output voltage would be higher around 32 ohm, vs 12V max at 300 ohm (Again, not sure about the max voltage spec)? Thanks in advance, hard to check online about..
I believe the 887 is a more powerful amp module than the 789. Since you own or have owned both amps which do you prefer?
 
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I believe the 887 is a more powerful amp module than the 789. Since you own or have owned both amps which do you prefer?
I changed dac and i'm not liking the current dac i have so i am waiting an ESS Soncoz LA-QXD1, since then i can't describe it more specifically sorry. I used to have the Topping d50 before and was very happy with 789. So i'm feeling the sound of 887 feels thicker vs the thinner 789, again i'm not 100% sure because of equipment used. But it will have 2W more power in balanced on 20ohm cans so not bad for that, better specs and a nice amount of lower output noise. I'm not sure if that 'thickness' which is nice, could end up on some detriments about speed, bloom, but probably not, just wondering :)
 

Rottmannash

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I changed dac and i'm not liking the current dac i have so i am waiting an ESS Soncoz LA-QXD1, since then i can't describe it more specifically sorry. I used to have the Topping d50 before and was very happy with 789. So i'm feeling the sound of 887 feels thicker vs the thinner 789, again i'm not 100% sure because of equipment used. But it will have 2W more power in balanced on 20ohm cans so not bad for that, better specs and a nice amount of lower output noise. I'm not sure if that 'thickness' which is nice, could end up on some detriments about speed, bloom, but probably not, just wondering :)
Is this the Monolith 887?
 

Veri

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I don't understand some things thing about max voltage, especially with those THX amps that has no findable specs;
Does the 6V max voltage level connected with 2V dac, are referred with normal gain in (1.0x gain, 0dB) output? Does it mean that with high gain in SE output (3.3x gain, +10dB) it will be 6V x 3.3= around 18V Maximium voltage?
The dashboard linked is single-ended 6.6V at max gain (2.0V at x3.3 gain = 6.6V ;) ).

Correct me if i'm wrong above, anyway... would be with balanced 4V dac's on balanced output with medium gain, double the maximum current?
Using balanced input will effectively double the output, but note that gain level III will now show clipping behaviour! Read the manual about this. On the other hand, using balanced output will quadruple the output like so: (0.9W => ~3.6W).
 
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The dashboard linked is single-ended 6.6V at max gain (2.0V at x3.3 gain = 6.6V ;) ).


Using balanced input will effectively double the output, but note that gain level III will now show clipping behaviour! Read the manual about this. On the other hand, using balanced output will quadruple the output like so: (0.9W => ~3.6W).
Oh thanks for the nicely sharp reply :D That's makes lot of sense.
About Wattage, the gain multipliers of unbalanced/balanced are always valid for every ohm avaiable for headphones?
And i'm a bit of a fish when it comes to Voltage numbers, so let me ask: If using a 4V dac and medium gain> 2.0x (+6dB) for avoiding clipping in most cases, this would be 4V x 2.0x gain= 8V Max voltage? A harder question: With max gain on balanced output, with balanced 4V dac (Tho clipping risks) 6.6x gain x 4V= 25Vrms > Will it reach 25V, or is it limited to lesser?
 

Veri

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About Wattage, the gain multipliers of unbalanced/balanced are always valid for every ohm avaiable for headphones?
And i'm a bit of a fish when it comes to Voltage numbers, so let me ask: If using a 4V dac and medium gain> 2.0x (+6dB) for avoiding clipping in most cases, this would be 4V x 2.0x gain= 8V Max voltage? A harder question: With max gain on balanced output, with balanced 4V dac (Tho clipping risks) 6.6x gain x 4V= 25Vrms > Will it reach 25V, or is it limited to lesser?
-Well yeah, the sensitivity of the headphone will determine the loudness that translates to.
-Correct. Max gain balanced is a tough one though, I don't know since it will crap out somewhere along the way, so not advised.
Note that single ended max gain (2V => 6.6V) is still less powerful than balanced middle gain. What are you driving, anyways?
 
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-Well yeah, the sensitivity of the headphone will determine the loudness that translates to.
-Correct. Max gain balanced is a tough one though, I don't know since it will crap out somewhere along the way, so not advised.
Note that single ended max gain (2V => 6.6V) is still less powerful than balanced middle gain. What are you driving, anyways?
25V max output voltage on 'clipping' high gain for THX 789? That's really hot if true..
Well for now an M1060c, than i would LCD-XC someday, guess both don't require much Voltage to perform well. But would also like to get back the Hifiman HE1000v2's as soon, so that's maybe harder to drive, but not insanely. Even tho i cannot find any specs for headphones requirements of Voltage, maybe it's the xxxdB/1V specification; instead Wattage is easy to determine in few search... So i yet to read all the sorderdude's tutorial https://diyaudioheaven.wordpress.com/tutorials/power-impedance-etc/ to understand the Voltage spec and the requirement of headphones.
I just like to have extra headroom than normal, that's why i also got 887 for 2W more watt at my 20 ohm planars, even if 8w instead of 6w is tiny more headroom. Would like to know on the voltage side, since i know planars need lot of headroom not only in Wattage, but Volts, the big ones are pretty demanding of power.
 
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