Massdrop THX AAA 789 ending shortly. First measurement posted.

[Sythrix]

I've been interested in this amp for a while and now it's near ending. I don't know if it was due to my complaining about the fact that there were none, but they've posted a measurement on the website.

I was wondering if anyone could take a look and tell me what you think. I'm not very experienced with interpreting things like this yet (especially when considering things like sample rate, FFT, and whatnot with respect to the measured results). It looks really good to my novice eyes... but again, what do I know?

I wish there were more, but at least it's something.

So... @amirm ? Anyone else care to comment? Meaningful measurement?

EDIT: Link to drop, Forgot to mention he told us the sample rate in a follow-up comment:

(One thing I inadvertently left out that should have been in the FFT configuration text in the graph is that bandwidth was 90k (192 kHz SR).)

 

[junki]

If this drop were extended to April 1st, I could hop onto it...

 

[amirm]

So... @amirm ? Anyone else care to comment? Meaningful measurement?

It is and shows extremely low level of harmonic distortion.

 

[amirm]

Oh, I just noticed it is at 300 ohms. It will produce more distortion at lower impedance loads.

Assuming 5.5 volt is the output, that represents 0.1 watts of power. So not much.

 

[Sythrix]

It is and shows extremely low level of harmonic distortion.

Might have to join then... Even though the wait is til Halloween...

 

[Sythrix]

Oh, I just noticed it is at 300 ohms. It will produce more distortion at lower impedance loads.

Assuming 5.5 volt is the output, that represents 0.1 watts of power. So not much.

So it's not quite as impressive as it first appears? I thought that might be the case. Although it probably is still pretty good. $350.... decisions, decisions.

 

[amirm]

So it's not quite as impressive as it first appears?

It is still good but not as much as I thought given the load. One of us has to buy it so that we can test it. My current thought is to buy the Monoprice one if someone wants to buy this one. That way we can compare them.

So please confirm if you or someone else is getting it.

 

[Rod]

It is still good but not as much as I thought given the load. One of us has to buy it so that we can test it. My current thought is to buy the Monoprice one if someone wants to buy this one. That way we can compare them.

So please confirm if you or someone else is getting it.

I got one. So this wont be good for 32 ohm hd-400i? There is 3 hours left to cancel.

 

[Sythrix]

It is still good but not as much as I thought given the load. One of us has to buy it so that we can test it. My current thought is to buy the Monoprice one if someone wants to buy this one. That way we can compare them.

So please confirm if you or someone else is getting it.

I am getting it. It's not supposed to ship til Halloween, so you'll have to wait a bit on those measurements, lol. Maybe we'll get lucky and it will ship early.

 

[amirm]

I got one. So this wont be good for 32 ohm hd-400i? There is 3 hours left to cancel.

We just don't know until they post the measurement. My intuition is that it will do well there too but no way to confirm sitting here.

 

[amirm]

I am getting it. It's not supposed to ship til Halloween, so you'll have to wait a bit on those measurements, lol. Maybe we'll get lucky and it will ship early.

Seeing how they have a prototype already that is out for measurement at jude's, tells me that it should come in sooner.

 

[Rod]

We just don't know until they post the measurement. My intuition is that it will do well there too but no way to confirm sitting here.

Decisions. I got this for the RME-adi2 dac to go with the planar headphones. My knowledge is limited on the tech.

 

[Sythrix]

Decisions. I got this for the RME-adi2 dac to go with the planar headphones. My knowledge is limited on the tech.

Hey, me too! Also have an RME ADI-2 DAC in the pipeline.

I have modded Monolith M1060s that I'm going to use with it.

 

[Rod]

Hey, me too! Also have an RME ADI-2 DAC in the pipeline.

I have modded Monolith M1060s that I'm going to use with it.

There supposed to ship next Tuesday from Sweetwater according to the salesman.

 

[mindbomb]

The THX chip is supposed to be a generational improvement over things like the LME49600 and the tpa6120a2 that are in a lot of stuff atm. And these measurements seem to confirm that. I'm just eyeballing it here, but for example, it appears to be about 100x cleaner than a magni 3, which itself was already pretty good at 300 ohms.

edit: disregard those numbers. i screwed up somewhere.

 

[Rod]

The THX chip is supposed to be a generational improvement over things like the LME49600 and the tpa6120a2 that are in a lot of stuff atm. And these measurements seem to confirm that. I'm just eyeballing it here, but for example, it appears to be about 100x cleaner than a magni 3, which itself was already pretty good at 300 ohms.

So if I got this right even if there impedance is not really optimized for 32 ohms it still should measure better than most amps out there because the measurements is so low to begin with. I dont even know what having a 300 ohm output and 32 ohm headphones will do. I know its just conjecture at this point.

 

[Rod]

Oh well I will keep it ordered. Find out when it gets here.

 

[Sythrix]

So if I got this right even if there impedance is not really optimized for 32 ohms it still should measure better than most amps out there because the measurements is so low to begin with. i dont even know what having a 300 ohm output and 32 ohm headphones will do. I know its just conjecture at this point.

They do have specs posted:

• THD: -143 dB, 300 ohms, 1 mW: 0.000007%
• THD: -140 dB, 300 ohms, 100 mW: 0.000010%
• THD: -125 dB, 32 ohms, 1 mW: 0.000056%
• THD: -123 dB, 32 ohms, 100 mW: 0.000071%

Etc...

A measurement would be nice for real contrast, but if this is an indication, it doesn’t seem bad by any means. Jude is supposed to post more later on, according to the head-fi thread.

 

[Rod]

I dont think that's even near audible range. I remember THD specs of the 1970's. I am curious though about what it is for lets say 3 watts. Thanks

 

[Sythrix]

I dont think that's even near audible range. I remember THD specs of the 1970's. Thanks

Yeah I don’t think it is either.

Also, it’s not a 300 ohm output or a 32 ohm output. The ohms are dependent on your headphones. They’re just the resistance the amp runs into. The actual output impedance is only 0.1 ohm (balanced) according to spec. Some amps can be tuned to drive certain ranges better, but it’s not a requirement or anything. Just determines how they’ll perform.