QC?
So, I was always so confused why people called the THX 789 thin sounding or brittle, because I never heard it that way with my chain. This was especially true with my Anandaâs that are already considered thin by some. It turns out my Modi 3 with varying apple iPhone/ipad chargers was giving me the fuller sound to complement the THX 789 already.
It seems chain is really, really important with this amp. I bought a DAC upgrade, a Denafrips Ares 2 DAC that I found far too forward and with a painful treble paired with the THX 789. After playing with my chain I did this
Mac->Audirvana->UPNP Raspberry Pi with Pi2Aes Running Volumio->toslink (monoprice)->Denafrips Ares 2->DIY Mogami Balanced Cables->THX 789->Diy Mogami balanced cables->KSC75/Ananda/LCD2c/Elex/HP50
They keys were
- Having Audirvana upsample to 4x power of 2 with a max of 192khz,
- Setting the THX 789 to high gain and keeping it there
- Never go above 9:00 on the volume dial
If you switch to a lower gain and turn the volume pot past 12 the treble becomes painful and the sound is too upfront. Itâs likes itâs screaming at you. This is also happens before any clipping can occur due to the balanced input.
Very efficient headphones/iemâs can go to lower gain settings as long as the volume is never past 9:00, but if the dynamics are lacking try high gain. With the above settings, I get the full bass slam with my balanced modded HP50 on medium gain, balance mod guide for those headphones pending.
This does not solve the imaging issues of the THX 789, left and right is no problem, but behind or forward I really need to close my eyes or try to concentrate on it. I donât know if this is better on higher end amps because I have never heard them.
Note that the mode of the Ares 2 dac NOS/OS/Filter are irrelevant for taming the THX 789. Choose whatever you like. P.S. if you have an Ares 2, spend 10 minutes to due the bass mod on YouTube it actually works (for me & others, YMMV).
If you need more than 9:00 on high gain, too bad youâre out of luck. I strongly suggest buying a different amp for your headphones.
That sucks. My Massdrop THX 789 doesnât seem to have those build issues. Itâs fairly solid feeling and well aligned.
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
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I recently purchased the 789 while Drop was discounting the price down to $250. So far I am pretty happy with the purchase but have a question for you experts out there. I am pairing this amp with a Creative AE-9 using unbalanced RCA out. I have a pair of HD800Ss. My question is, is it worth it to switch the DAC to a topping D30 Pro for balanced output?
Depending on the output power from your current dac you might be able to drop a gain stage and have less noise if the d30 pro is something like twice the output of the creative. Also the d30 is just gonna be all around better.
Hmm, I donât know how to measure the output power from the sound card. The specs provided by Creative are all assuming the provided amp is used, but I tossed that thing to the garbage.
Did you buy it only for the 789? Thatâs a really expensive upgrade considering the price of the amp itself. Though if you were planning to upgrade to a soloist or something later, it doesnât hurt to get it now.
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Yep just for the 789 . Iâm a mad lad . I really like the sound or non sound of the THX789, I want a 789 but bigger and do not want to spend several thousand dollars on benchmark THX tech. I really like the form factor and sound. I have more expensive amps but this one I want to improve. Long story short I am really happy with the purchase. It fixed the problems I wanted it to fix. The sound is more cohesive and actually sounds like a 6 watt amp now. I was going to write a glowing review of the Burson supercharger but I am not a reviewer. I had pictures of my 2 THX amps the splitters I used and everything but I realized that the Burson power supply is probably not amazing just the included power supply with the THX789 is probably crap.
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It is on sale right now for 199$. I donât know if it is the lowest recorded price yet. What I would like to know is, is it still relevant in 2021 considering the competition. I am interested in buying a Topping L50 and would like to know how do they compare. L50 would come for 219$ including shipping and 789 would be for 209$ with shipping. I live in Turkey and assume custom clearance might come cheaper on L50, since on aliexpress, there are some âworkaroundsâ
This is the lowest Iâve seen the 789 go for. At that price it is temping, but wondering if it makes sense. I already have an Asgard3 and love it. Wondering if it makes sense to have this too.
Iâm so tempted to sell my SP200 for this, I know the THX-888 is âbetterâ but the better quality parts makes this so tempting.
This amp is old and out of favour, and I have better amps, but Iâm a stubborn tinkerer. I have replaced the pot in mine with a resistor ladder attenuator and added a cheap Jameco linear regulated power supply. This thing actually has something resembling micro dynamics now. I had to remove a relay that muted the output when switching from single ended to balanced to fit the new attenuator though.
I went down the rabbit hole a little bit on the next mod. The original PCB has space for two capacitors unused. This made me think, âBut why?â After a few days of reading and posting on other forums I theorize that I know why.
You can use the best linear pixie dust power supply on this amp, but it wonât do much good because the this magical pristine perfect 24v signal goes through something called a rail splitter or virtual ground that splits the 24v signal to +12V and -12V. This can add its own noise in to the circuit. Of course if youâre using a crappy switching power supply itâs noise goes through the same rail splitter and creates problems past that.
There are two capacitors that are smack dab in the middle of the two 12V rails coming out of the rail splitter and the OPA564 op amp that actually does all the amplifying in this thing. Dirty power to an op amp means crappy results. Now, you may ask, âWtf are you talking about because this thing measure perfect!â Actually, it doesnât. If you look hard enough on the internet youâll find that when this amp is singled ended only and left ungrounded noise does get through. Another objectivist blogger showed that high frequency noise is also present in stock form, but this is considered inaudible. My experience is that just because itâs inaudible doesnât mean it canât be fatiguing.
Itâs also an open secret that amp was cost cut to hell before it was released and the crappy volume knob was one such casualty. Evidence seems to point that these caps are another casualty.
So, back to the empty space for caps. I plan to add two caps in total. A 6800 uF 16V cap for each rail as that is what would meet the lead spacing and diameter of the original silkscreen/pcb, and a 0.1uF film. These caps are in parallel with the existing 3300uF 16V cap. The 6800 uF cap will decrease ripple voltage by well over a factor of 2, and the film cap will filter the high frequency noise coming to the OPA564 op amp.
There ARE NO other bypass caps that filter high frequency noise on this amp coming from the power supply. This thing seems to rely solely on its âfeed forwardâ technology to error correct, letâs try cleaning up the rails first so that there is less to correct. It is also generally considered good practice to have a bypass cap before the op amp anyways.
If you feel the above is retarded feel free to rebuke me, I wonât be offended.
No rebuke. How about a step by step tutorial with lots of pics.
I actually finished this little project and moved on, but two things.
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with the mods itâs still a mediocre headphone amp.
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with the mods itâs an even better BA IEM amp. It sounds like a really, really good tube amp. Like better than a fully modded up bottle head crack with a 6xx good. I use mine with a Kiwi Orchestra Lite these days.
If people were interested I guess I could post instructions. Hereâs some photos.
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Nice⊠kid has skill.