Massdrop x THX AAA™ 789 Linear Amplifier - Impressions Thread
Mar 16, 2021 at 4:42 PM Post #2,386 of 2,613
In general, footers are designed to drain or mitigate excess energy and vibration away from the component to increase resolution, lower distortion and provide an audibly cleaner and clearer result. IME, different materials do different things, and in practice results can vary widely -- better, worse or no difference at all. I've never been a fan of brass for most components because they seemed to exacerbate high frequency energy and tend toward being brighter and more metallic sounding (guess that makes sense considering they're brass). For whatever reason, this amp seems to respond well to these footers in my system. I surmised it might be because it's such a light amplifier, but I have no idea. It's always a crapshoot with tweaks like this. I don't think they would do anything toward blocking any EMI/RF interference, that's not their purpose. But I hear an audible improvement in the way I described above.

Weights have long been used on components to sort of do the same things as the footers -- decrease vibration. I've tried this a couple times on various components in the past and I heard no difference. However, on this particular amp, I do.
Vibrations from what though, and how do vibrations effect a solid-state circuit that's simply passing electricity through it? This isn't a speaker amp with subwoofers running and tubes to pick up microphonics and it would seemingly take a fair bit to destabilize any of the other components (see prior subwoofer comment) if it were affected at all. If you wanted to prove it you could turn around, play some music, and have someone start tapping on the amp when you aren't looking and see if you can tell the difference.
 
Mar 16, 2021 at 5:10 PM Post #2,387 of 2,613
Vibrations from what though, and how do vibrations effect a solid-state circuit that's simply passing electricity through it? This isn't a speaker amp with subwoofers running and tubes to pick up microphonics and it would seemingly take a fair bit to destabilize any of the other components (see prior subwoofer comment) if it were affected at all. If you wanted to prove it you could turn around, play some music, and have someone start tapping on the amp when you aren't looking and see if you can tell the difference.
Honestly, a lot of the marketing material for these types of tweaks can be pretty eyebrow-raising stuff in terms of believability. There's probably some truth behind it but in the end (for me at least), hearing is believing. My take is that vibrations (if there are any) are probably minimal. What could be vibrating inside the chassis, unless you've got a massive power supply and some sort of physical hum, or maybe tubes prone to microphonics or the like. Something with moving parts like a TT or disc player, perhaps more so. But it could be that even minute vibrations could translate to smearing or a level of audible distortion, especially when you're listening through high fidelity headphones.

What I surmise is that the physical material of the footer in contact with the chassis makes more of a difference to what you might hear. If you try different types of footers (brass, wood, rubber etc) you'll probably hear a difference, and differences between them. At least I have and do. But I can't get into the weeds behind the science since honestly I couldn't really care less. It's the same thing behind 'bits are bits' and all cables should sound equal, etc etc. You're getting into murky territory. I'm much more simple -- do I hear a difference, ok. Do I like the difference? Ok or not ok.
 
Aug 26, 2021 at 3:00 PM Post #2,390 of 2,613
It looks like this thread has really slowed down. As well I see a lot of THX 789 for sale. Anyone here still using their 789? If not what have you moved on to?

I bought mine last winter when it was at it's lowest price out of curiousity. I didn't like it at the time and it didn't match well with my phones or DAC. I recently made some changes and wanted to put a second system together. Dug it out of the closet and this time around I think I am feeling the magic. It feels lush and thick, and there is more depth. This is with my Elears and gain set to 2. I suppose it still will be incompatible with my LCD-X.

Anyone still using theirs?
 
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Aug 26, 2021 at 3:02 PM Post #2,391 of 2,613
It looks like this thread has really slowed down. As well I see a lot of THX 789 for sale. Anyone here still using their 789? If not what have you moved on to?

I bought mine last winter when it was at it's lowest price out of curiousity. I didn't like it at the time and it didn't match well with my phones or DAC. I recently made some changes and wanted to put a second system together. Dug it out of the closet and this time around I think I am feeling the magic. This time around it feels lush and thick, and there is more depth. This is with my Elears and gain set to 2. I suppose it still will be incompatible with my LCD-X.

Anyone still using theirs?
Yeah, every single day for many hours. I've got it with the Audioengine D1 and ORA GQ headphones. To my ears, they sound incredible together.
 
Aug 26, 2021 at 4:27 PM Post #2,393 of 2,613
It looks like this thread has really slowed down. As well I see a lot of THX 789 for sale. Anyone here still using their 789? If not what have you moved on to?

I bought mine last winter when it was at it's lowest price out of curiousity. I didn't like it at the time and it didn't match well with my phones or DAC. I recently made some changes and wanted to put a second system together. Dug it out of the closet and this time around I think I am feeling the magic. It feels lush and thick, and there is more depth. This is with my Elears and gain set to 2. I suppose it still will be incompatible with my LCD-X.

Anyone still using theirs?
Just a lot more competition these days and cheaper amps perform really well. The 789 is still great.
 
Aug 26, 2021 at 10:57 PM Post #2,394 of 2,613
It looks like this thread has really slowed down. As well I see a lot of THX 789 for sale. Anyone here still using their 789? If not what have you moved on to?

I bought mine last winter when it was at it's lowest price out of curiousity. I didn't like it at the time and it didn't match well with my phones or DAC. I recently made some changes and wanted to put a second system together. Dug it out of the closet and this time around I think I am feeling the magic. It feels lush and thick, and there is more depth. This is with my Elears and gain set to 2. I suppose it still will be incompatible with my LCD-X.

Anyone still using theirs?
I use mine with any sub 300 ohm impedance headphones. I leave those for my Magni, which even on low, gets way too loud with any other headphones. I love the THX for its crystal clear sound. The Magni has a bit more oomph, but the THX is more accurate.
 
Aug 26, 2021 at 11:48 PM Post #2,395 of 2,613
I still use mine. Powerful enough for any headphone, measures in the top 1% of amps, very low output impedance. The only reason to spend more is to spend more.
 
Aug 27, 2021 at 12:52 PM Post #2,396 of 2,613
It looks like this thread has really slowed down. As well I see a lot of THX 789 for sale. Anyone here still using their 789? If not what have you moved on to?

I bought mine last winter when it was at it's lowest price out of curiousity. I didn't like it at the time and it didn't match well with my phones or DAC. I recently made some changes and wanted to put a second system together. Dug it out of the closet and this time around I think I am feeling the magic. It feels lush and thick, and there is more depth. This is with my Elears and gain set to 2. I suppose it still will be incompatible with my LCD-X.

Anyone still using theirs?

I have mine. I got it to replace my Atom amp. I wanted to the better volume knob and the heavier weight (the Atom is very light and moves around when trying to plug/unplug).

And the RCA passthrough actually works better for me than preamp outs since I'm using a speaker amp with its own volume control. I don't even have to turn on the THX 789, as the passthrough is active without power to the 789.
 
Sep 18, 2021 at 1:49 AM Post #2,400 of 2,613
Currently $199, directly from mDrop: link to Drop.com
Just picked one up for that price, seems like a bargain at that price for what you get. Let's see how it powers my k340s 🤔

Update: not quite up to powering the K340 in SE mode. Might go for balanced..
 
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