Massdrop x THX AAA 789

You cannot pull the pcb out. You will have to push it out (as I mentioned earlier) because the front plate is attached to the pcb. You may also want to pull on the front panel (specifically, its slight surrounding ridge) while pushing out the pcb.

Additionally, I used the liquid-type deoxit rather than the spray-type deoxit because the former is said to be longer lasting. I don't know if the difference is actually true, but I do know that I tried using some no name Home Depot electrical contact cleaner to fix a similar issue with the Magni 3 and that stuff did not last for even a week before the scratchy volume pot returned. Since the 789's PCB is easy to access and push out from the casing, you can try to see if the spray deoxit works out with you.

For my non-Drop branded 789, I found pushing the pcb out from the casing to be pretty easy. Even if you have the Drop-branded 789, I doubt that Drop changed any of the casework to make it difficult to push the pcb out. Then again, I don't really know.

EDIT: Whoops, there's also a bottom screw that you have to take out, see below (4:58). I forgot about that part.

 

that guy is nuts. But my Drop 789 PCB definitely did not slide out like that. I couldn’t figure out what the hell was holding it in there. I could rattle the pcb up and down in the track but it was somehow attached at the front.

BUT spraying deoxit at the back of the pot from the back without removing the PCB, then turning it face down and turning the knob back and forth for a few minutes worked great. I could actually feel the knob loosen up as I turned it. It’s now buttery smooth and there is no static at all.

very easy to do you just remove the screws , take off the back plate spray the deoxit, work it in and it’s fixed. We’ll see how long it lasts. But I don’t mind doing that every few months if I have to.

So thank you!

 

^RD, the PCB is probably held in by the volume & gain knobs. The shafts of the pot and switch go through holes and the attached knobs will keep the PCB from releasing out the back.

Some of the amps also have standoffs that are screwed in from the bottom like the MCTH.

 

I was trying to pull it out from the front. And I unscrewed the bottom screw. I don’t know wtf was holding it so tight. I actually pushed really hard on the back of the PCB and it did not budge. Oh well though I got the job done.

 

The front panel is held into place by long tie rods in all 4 corners that pull the faceplate on from the back of the amp.

That way most of the amp is very clean with no screws except the back (and maybe the bottom).

Sorry you had a wrestling match with it and glad you were able to quiet the pot!

 

Hello everyone. Since creating an account and reading SBAF threads, I have found this site to be very unbiased and informative. I am just wondering how a THX or similar amp stacks up against other amps in 2021. I remember back when the THX 789 was launched, the senior members here are quite impressed. But when I go to the Topping A90 thread, the reviews are generally not good even though it is supposed to be better than the THX 789. So is a cheaper THX amp worth getting? Thanks

 

FYI SMSL SH-8s is basically a Drop 789 clone. Same op-amps, same THX feedback, same same. The A90 is different, more like Magnius, or more specifically it's an L30 made balanced powered by meanwell PSUs rather than a VAC power brick.

I would assume all of these will sound pretty similar..

 

The THX amps are still well liked by the IEM crowd but just gained the IEMagni as competition on that front.

For headphones people around here tend to prefer aiming for gear synergy. So rather than viewing amps in terms of good, better, best. It's more like what flavour are you after for your [insert headphone here] and matching source gear to taste.

What gear do you own? Do you have existing preferences or are you still working that out?

 

Thanks the the reply. I have ordered a HiFiMan Ananda which is arriving in 3 weeks. It is quite neutral so probably a warmer amp might be better. I have considered the Asgard 3, but it will take literally months for it to arrive. Right now I have an iFi Zen Dac, which is quite good and warm but only has about 300mW into 32 ohms. Do you think zen dac + THX would make a good chain with the Ananda?

 

I'd consider the THX a downgrade from the iFi Zen Dac based on my experience with the HE1000se, but YMMV.

 

Thanks for the advice, Marv. I will come back if it doesn't work out for me.

 

I just received (my own purchase) a Burson Super Charger 3A power supply for the THX789 , It works perfectly. Initial impressions are good. Have only heard a macrodynamics increase so far. I will pull out my 2nd THX789 and test it on the standard power supply and switch back and forth . So far I have only Tested it on Argon Mk3s (since that is my hardest to drive headphone). If anyone has any constructive A B testing advise on what to listen for or tips let me know, thx

 

I recently used the discount Monoprice EU held on the THX AAA 887 amp and got it for "cheap" (275€ vs the 350€ they normally ask for). This is basically a clone of the Massdrop version.

OMG, this is soooooo booooorrrrring to listen to. Ugh, makes listening to music a chore. How does it manage to be so incredibly insipid?! Feels like eating air, you kinda do the mouth work required, but you are never satisfied. I try to start tapping my foot, but I can't.

I agree with what everybody said here, it's super clean, separates everything there is to separate, doesn't sound like anything at all (not warm, not cold, not bright, bassy, no nothing) and has a lot of power on tap. The stage is weird with this one. It's infite to the left/right side, but there is no depth at all. Bass sounds to me almost subdued, but this probs is because my previous amps elevated it. Slam is minimal, makes it sound even more boring than it is already.

I am going back to the iFi Zen Can. I am surprised this was as hyped up as it was. Seriously just f**k r/headphones and ASR.

 

I agree with everything you say. Just try them with IEM's if you have any. Even the 1/8" unbalanced out. It is really the one thing this amp is good at IMHO.

 

I’ve posted multiple times that the THX 789 to a a God awful full sized headphone amp and should only be purchased for BA iem use for which it beats everything else for unknown reasons especially with an upgraded power supply. Mine with a Sigma 11 LPS makes BA iems much more dynamic and really works against BA timbre among other things.

Maybe I need to be more vocal about this.

The THX 789 to a a God awful full sized headphone amp and should only be purchased for BA iem use. BE WARNED.

 

It does have a certain magic with IEM's. So maybe asking it to do much else is asking too much.

 

Yeah, the only IEM I got is a Blon BL03... Back to Monoprice this amp goes. It was an educational experience for sure.

 

Hybrid IEMs will still work good, but may not get the results you want from the DD driver in that Hybrid IEM.

 

My Solaris sounds awesome from the 789.

The best description I’ve read for the 789 with full size headphones is “Saran Wrap for headphones”