Review and Measurements of Massdrop THX AAA 789 Amp

[pos]

Anyone know of any 1.05Vrms SE / 2.1Vrms BAL DACs out there?

Geshelli Labs ENOG2 PRO: https://www.audiosciencereview.com/...nog2-pro-dac-fully-balanced.5372/#post-119169

 

[Jorj]

Well, it's been nice knowing you all.... My stack is complete, and until the Smyth Realizer decides to become non-vapourware, I get to just listen to music. This setup sounds soooo good. My thanks to Amir for pointing out the best values in personal audio (and for parting with his beloved DX7). I'm having a blast. I could gush a while about inky-this and slam-that, but we already know how well this gear works. I feel confident that I can plug any set of cans outside of Stax into this stack and not worry about it. Job done.

 

[Roen]

Geshelli Labs ENOG2 PRO: https://www.audiosciencereview.com/...nog2-pro-dac-fully-balanced.5372/#post-119169

No USB? sadface.

 

[amirm]

Well, it's been nice knowing you all....

If I had known you were going to leave us, I would not have sold you my DX7!!!

Seriously, those two look really good together. The DX7 doesn't have the ESS hump and is a great performer and match to THX 789.

 

[Pillars]

Well, it's been nice knowing you all.... My stack is complete, and until the Smyth Realizer decides to become non-vapourware, I get to just listen to music. This setup sounds soooo good. My thanks to Amir for pointing out the best values in personal audio (and for parting with his beloved DX7). I'm having a blast. I could gush a while about inky-this and slam-that, but we already know how well this gear works. I feel confident that I can plug any set of cans outside of Stax into this stack and not worry about it. Job done.

View attachment 18167

There is always that last ounce to squeeze out. I'd recommend doing some light mods on the 6XX - I really enjoy the benefit there. I also use a DX7(s)+THX 789 and while it absolutely gives forth the most detail, resolution and amazing sound it isn't the most musical combination I've got.

 

[Jorj]

If I had known you were going to leave us, I would not have sold you my DX7!!!

Seriously, those two look really good together. The DX7 doesn't have the ESS hump and is a great performer and match to THX 789.

Oh, I won't go anywhere, it was just wishful thinking. I just looked and that damn monkey is still back there!

 

[Jorj]

There is always that last ounce to squeeze out. I'd recommend doing some light mods on the 6XX - I really enjoy the benefit there. I also use a DX7(s)+THX 789 and while it absolutely gives forth the most detail, resolution and amazing sound it isn't the most musical combination I've got.

So far the only mod on the HD6xx is to trash that abysmal cranium-creasing top pad. Pray, tell us what is your more musical transducer solution? I'm kinda eyeing the HD800. See, the monkey speaks.

 

[Roen]

There is always that last ounce to squeeze out. I'd recommend doing some light mods on the 6XX - I really enjoy the benefit there. I also use a DX7(s)+THX 789 and while it absolutely gives forth the most detail, resolution and amazing sound it isn't the most musical combination I've got.

What mods on the 6XX? I have one coming in.

 

[confucius_zero]

Does this amp have a passthrough to output an unamped line out to the speaker amplifier?

 

[Jorj]

Does this amp have a passthrough to output an unamped line out to the speaker amplifier?

Indeed it does, but the passthrough is single-ended RCA only. The XLR inputs are not passed to the RCA. The passthrough works regardless of whether or not the amp is on.

 

[dinglehoser]

Indeed it does, but the passthrough is single-ended RCA only. The XLR inputs are not passed to the RCA. The passthrough works regardless of whether or not the amp is on.

Side note: the Massdrop LCX also has passthrough line out, but unlike the 789, the LCX must be powered on for it to work correctly. With the unit off, the signal passes through, but it is very audibly distorted. The 789 does not suffer from this issue (no audible change between power states).

 

[AresHarvest]

Pretty sure you can get XLR to loop through the SE PASS outputs if you really wanted to. Break internal wiring to SE PASS, then 2 jumpers each for L and R balanced inputs (XLR pin 1 to RCA sleeve, XLR pin 2 to RCA tip)

Edit: but at that point it would just be worth it to roll a wye cable with XLRM and RCA at the destination end, instead of opening up the amp

 

[Music1969]

Hi @AndrewMason

Regarding the following spec:

• Single-Ended Output : Output power: 3000 mW, 16 ohms, <1% THD (watts per channel)

Is the single ended output stable and with low distortion, at 8-ohms?

Can you kindly share some figures at 8-ohms (current output for <0.1% THD and <1% THD)

Cheers

 

[rajapruk]

Over 1000 units sold now by Massdrop.

 

[Schackmannen]

Over 1000 units sold now by Massdrop.

Still waiting for mine, it's been in transit for over 2 weeks, DHL sure are taking their time. Funny thing is that it took them one day to get the package from the US to Germany once they had finished processing it in the US but then it's been stuck in Germany for a week

 

[BurritoJustice]

Hi @AndrewMason

Regarding the following spec:

• Single-Ended Output : Output power: 3000 mW, 16 ohms, <1% THD (watts per channel)

Is the single ended output stable and with low distortion, at 8-ohms?

Can you kindly share some figures at 8-ohms (current output for <0.1% THD and <1% THD)

Cheers

The minimum supported impedance is 12ohm, and that is only up to 4V output for 12-16ohm. For whatever reason the the AAA design seems to have issues at extremely low impedances.

It is reported in the manual that it can easily cause damage and will void the warranty, so I recommend against it.

Consider getting an IEMatch or similar to bring the impedance up if you are looking at IEMs, if you are looking at driving loudspeakers with the 789 then definitely reconsider (don't do this).


I also have to say, the 789 has a really fantastic potentiometer. After the terrible experience I've had with all my previous pot-based amps I was considering adding a relay ladder preamp, or going diy and trying to add an AMB δ1. It's easily the nicest potentiometer I've used and is bested only by the relay/digital setup in the ADI-2 Pro.

 

[Music1969]

The minimum supported impedance is 12ohm, and that is only up to 4V output for 12-16ohm. For whatever reason the the AAA design seems to have issues at extremely low impedances.

Thanks but Andrew has said "The manual should say ... can tolerate loads between 12 and 8 Ohms"

Hence my queries to Andrew about 8 ohms performance (current output for <0.1% THD and <1% THD)

https://www.massdrop.com/buy/massdrop-x-thx-aaa-789-linear-amplifier/talk/2249304

Also @AndrewMason - what is the DC voltage input range and max. power consumption? And does it take 5.5mm x 2.1mm DC plug?

 

[maverickronin]

The minimum supported impedance is 12ohm, and that is only up to 4V output for 12-16ohm. For whatever reason the the AAA design seems to have issues at extremely low impedances.

I wouldn't worry about that with IEMs at all. They are so sensitive that it doesn't matter. They will flat out explode before the 789 gets anywhere near its limits.

There might be some low efficiency planars here and there that will have an issue with it but that would be it.

 

[AndrewMason]

Hi @AndrewMason

Regarding the following spec:

• Single-Ended Output : Output power: 3000 mW, 16 ohms, <1% THD (watts per channel)

Is the single ended output stable and with low distortion, at 8-ohms?

Can you kindly share some figures at 8-ohms (current output for <0.1% THD and <1% THD)

Cheers

Sorry we dont have those curves for 8 Ohms. But like all AAA, distortion remains extremely low even at high current. Peak current is approx 0.9Apk before protection invokes.
Also beware the limitations on driving low impedance like this. See the owners manual.

 

[AndrewMason]

Thanks but Andrew has said "The manual should say ... can tolerate loads between 12 and 8 Ohms"

Hence my queries to Andrew about 8 ohms performance (current output for <0.1% THD and <1% THD)

https://www.massdrop.com/buy/massdrop-x-thx-aaa-789-linear-amplifier/talk/2249304

Also @AndrewMason - what is the DC voltage input range and max. power consumption? And does it take 5.5mm x 2.1mm DC plug?

24.0 vdc +/- 5% regulated supply, and yes 5.5x2.1mm.