Massdrop THX AAA 789 ending shortly. First measurement posted.

[amirm]

I have a question. How would you convert the headfi thd measurement (which I guess is .00003%) into thd+n?

The graph says they used 1.2 million points in the FFT. That results in a 58 dB or so reduction in measured noise floor versus reality. Compensating for that, noise floor rises up to:

where I have drawn the crooked red line. In other words, all of those distortion spikes disappear in noise.

This is why I don't use such large FFTs. It brings out stuff that is just too far below actual noise floor.

Converting the above noise floor to percentage we get approximately 0.0003% THD+N ( I am assuming the harmonics will be literally in the noise).

 

[amirm]

But to vent, I'm about = this close to quitting this hobby because there are literally just mean, pretentious, fucking stupid as fuck cliquey circlejerks everywhere I go. All I want is some goddamn honest-to-self subjective impressions coupled with consistently measured, holistic measurements with honest, measured insights into both the good and bad. If there was only a goddamn website that did that, it'd be the best. Oh wait, InnerFidelity's got the headphone part of the market cornered. Open season for DAC/amps.

I don't want to paint us as saints or holders of ultimate truth. I can tell you that we are committed to producing the best objective data and science/engineering behind audio products anywhere. To wit, one day I hope we have measurement data for vast majority of audio products out there. At the pace we are going, we have produced more of that data that some magazines do in years!

On subjective data, for headphone amplifiers and possibly for power amplifiers I will continue to provide controlled listening data (level matched, proper AB tests, etc.). Other members have also been providing some of the same. We don't put any value on fully subjective, anecdotal reporting that you see elsewhere. I can show them to all be completely wrong to the person reporting, or anyone believing them. In the past I have offered more than $1000 for them to show them to be correct. I can't think of anything more maddenning than trying to make sense of subjective reports of audio in the wild or among reviewers. It is at the core of this forum to create reliable data and explanation of technology that is defensible and backed by best practices in audio research and engineering.

As for mean spirited cliques, it is unfortunately prevalent elsewhere. And it spans both objective and subjective sides of the argument. I can't stand either one and hence the reason this forum exists. Read our mission statement on every page of this forum. You see that we believe in having fun above everything else.

But again, we are not perfect. Marrying to a bunch of strangers is never easy. One thing I can tell you though: you will never, ever be talked down to like you were at the other forum.

 

[Kyle / MrHeeHo]

Don’t know how comparible it would be coonsidering the difference use case but the Benchmark AHB2 Power Amplifier also uses THX AAA technology https://benchmarkmedia.com/products/benchmark-ahb2-power-amplifier


Edit: Ah I see this has already been mentioned in another thread

 

[readysetgo]

You see that we believe in having fun above everything else. But again, we are not perfect.

My trick for this in life has always been to have as few rules for yourself as possible that you never break under any circumstances. Only the most life critical ones go on the list, because when you make rules that are easy to break it lessens the importance of them. At the top of the list is my most important one: Never become bitter.

 

[Rod]

As long as measurement settings are consistent from one measurement to another, that's the most important thing. @amirm can measure everything at 5.5 Vrms into C ohm if he just stays consistent with it so we can compare apples to apples. Two arguments for setting that consistent level down are:

1. Most people don't listen at 5.5 Vrms, but knowing maximum THD+N characteristics at maximum output and gain is academically interesting.
2. The maximum output of different amps are different.
3. Many published specs show metrics @ 1 Vrms. Those who also show specs at maximum output have balls.

Btw, I'm the guy in that MCTH thread. I'm obviously no one's minion and am using my own mind and judgement to editorialize information I get here and elsewhere, objective or subjective, for the optimization of my own purchases.

But to vent, I'm about = this close to quitting this hobby because there are literally just mean, pretentious, fucking stupid as fuck cliquey circlejerks everywhere I go. All I want is some goddamn honest-to-self subjective impressions coupled with consistently measured, holistic measurements with honest insights into both the good and bad. If there was only a goddamn website that did that, it'd be the best. Oh wait, InnerFidelity's got the headphone part of the market cornered. Open season for DAC/amps...

Robert Coover: “The superhero, his underwear bagging at the seat and knees, is just a country boy at heart, tutored to perceive all human action as good or bad, orderly or dynamic, and so doesn’t know whether to shit or fly.”

 

[no1boss]

I'm not sure how Massdrop works, will this be available again if there are enough requests?

 

[amirm]

I'm not sure how Massdrop works, will this be available again if there are enough requests?

Usually yes.

 

[Sythrix]

I'm not sure how Massdrop works, will this be available again if there are enough requests?

I don't know if you were ever informed, but it is indeed available again.

Also, it appears they have made some changes. I received this email:

"Hi everyone,

The Massdrop x THX AAA™ 789 Linear Amplifier is making its way through production! We also have some important updates to share about the gain specifications.

We worked with THX to adjust the gains for the primary use case of the Audiophile community. Previously, the gains were optimized for variance in source output power. Most Audiophiles typically use 2V DAC sources and wish to drive in-ear monitors or hard-to-drive headphones.

With these slight changes there were some updates to the gain specifications, which we have listed below:

General:

Frequency response: + 0.01 dB / - 0.03 dB 20 Hz–20 kHz; + 0.05 dB / - 0.15 dB 10 Hz–50 kHz

Balanced Output:

THD: -130 dB, 32 ohms, 1 mW: 0.000032%

THD: -130 dB, 32 ohms, 100 mW: 0.000032%

THD: -122 dB, 16 ohms, 1 mW: 0.000080%

THD: -122 dB, 16 ohms, 100 mW: 0.000080%

Gain: 0.66x , 2.0x, 6.6x (-4, +6, +16 dB), selectable via front switch

Single-Ended Output:

Output power: 1800 mW, 32 ohms, <1% THD (watts per channel)

THD: -135 dB, 300 ohms, 100 mW: 0.000018%

THD: -133dB, 32 ohms, 100 mW: 0.000022%

THD: -130 dB, 16 ohms, 1 mW: 0.000032%

THD: -125 dB, 16 ohms, 100 mW: 0.000056%

Gain: 0.33x , 1.0x, 3.3x (-10, 0, +10 dB), selectable via front switch

We’re on track to meet our estimated ship date of October 31, and we'll check back in around the middle of October with the status of the shipment."

Not sure how I feel about them making changes this late in the game. I guess it doesn't really affect me and my usage scenario.

The current drop will ship Feb 15, 2019.