Massdrop x THX AAA™ 789 Linear Amplifier - Impressions Thread
Oct 28, 2018 at 12:05 PM Post #196 of 2,613
I agree - very impressive.
For people who like total flat and uncolored amp - this is a very good one!
I had a prototype for a week or so, and was very impressed with its flat and transparent sound.
Personally, not my cup of tea (I like warmer / tubey amps), but great amp never the less :)
That's why my friend I have Glen OTL for tubes and THX for flat as a board solid state sound.
 
Oct 28, 2018 at 12:15 PM Post #197 of 2,613
That's why my friend I have Glen OTL for tubes and THX for flat as a board solid state sound.
Hey Doc buddy :)
Yeah... after playing with the Glenn OTL at RMAF 3 weeks ago - I am in the process of ordering one, too!
For me, the THX is too flat, but I can definitely see a big audience who would love it.
 
Oct 28, 2018 at 1:49 PM Post #198 of 2,613
My point is that another thread should be started about the issue, so that folks with faulty units can search for it, find it easily and then discuss it there. This thread should be used for listening impressions. Does that not make sense?
I would have trouble finding that because I am part of the massdrop and subscribed to this thread. This is awesome if mine got the same issue. Nothing say only listening impressions and no build quality impressions is allowed.
 
Oct 31, 2018 at 12:32 AM Post #204 of 2,613
I wonder how Jotunheim and topping dx7 compare to THX in terms of sound. Can you to prove some insight?

Jotunheim is ass, it is rolled off and sounds just "off". In balanced it has okay power, but for the price THX >>> DX7 (it's ok but cheap cinese made) > Jotunheim (noisy and rolled-off).
@Baten, do you have all three of them? That question was for @Alcophone.
 
Oct 31, 2018 at 2:21 AM Post #205 of 2,613
I wonder how Jotunheim and topping dx7 compare to THX in terms of sound. Can you to prove some insight?
I only use the DX7s as a DAC and preamp. The few times that I tried its headphone amplifier, I found the sound pretty mediocre, but I also never intended to use it for that, so I didn't try for long. Good enough to burn in headphones, though. :)
With both a DX7s and a Jotunheim handy, I'd use the DX7s as a balanced DAC into the Jotunheim. If the choice is between either a DX7s or a Jotunheim with DAC module, I'd go for the Jotunheim. In comparison with the Gustard H20 (with Sparkos SS3602s) I noticed that the Jotunheim flattened the Yggdrasil's sound stage (with my Ether C Flow - the sound stage with Jotunheim and internal DAC module was plenty big when I tried the Sennheiser HD800). Not a problem with the DX7s as a DAC because there the sound stage seemed flat to begin with (even with the H20). I wish I had a pair of HD800 just for sound stage testing. Still unsurpassed in that area.

I haven't spent enough time with the THX amp yet to reach a firm conclusion, but I can give you some impressions (that should make someone here very happy!). With a balanced source and balanced headphones, it's doing a fine job. Clean, full, tight sound. Transients still seem slightly rolled off to me, which can be relaxing, but also takes some of the excitement out of certain recordings, especially with guitars. When I used the iFi micro iDSD as a DAC (i.e. single ended), THX as the amp, and using a single ended cable for my Ether C Flow, I was not happy with the sound. The balanced output with the same DAC and headphones was solid. I have to use it more with my other headphones, I did like what it did to my Focal Listen (single ended only), though I mainly use them straight out of my phone, so any proper amp might impress me with them.

I find it concerning that the THX amp's manual states this:
CAUTION: Please remember to turn down the volume completely (or power down) before plugging or unplugging any sources or headphones to/from your 789.
That makes proper A/B-ing (with level matching) very tedious at best. It's also very easy to forget. And I can still just barely hear some music playing with the volume all the way down (balanced in, balanced out, medium gain, Ether Flow). Luckily, it has survived all my mishaps so far.
 
Oct 31, 2018 at 3:09 AM Post #206 of 2,613
I only use the DX7s as a DAC and preamp. The few times that I tried its headphone amplifier, I found the sound pretty mediocre, but I also never intended to use it for that, so I didn't try for long. Good enough to burn in headphones, though. :)
With both a DX7s and a Jotunheim handy, I'd use the DX7s as a balanced DAC into the Jotunheim. If the choice is between either a DX7s or a Jotunheim with DAC module, I'd go for the Jotunheim. In comparison with the Gustard H20 (with Sparkos SS3602s) I noticed that the Jotunheim flattened the Yggdrasil's sound stage (with my Ether C Flow - the sound stage with Jotunheim and internal DAC module was plenty big when I tried the Sennheiser HD800). Not a problem with the DX7s as a DAC because there the sound stage seemed flat to begin with (even with the H20). I wish I had a pair of HD800 just for sound stage testing. Still unsurpassed in that area.

I haven't spent enough time with the THX amp yet to reach a firm conclusion, but I can give you some impressions (that should make someone here very happy!). With a balanced source and balanced headphones, it's doing a fine job. Clean, full, tight sound. Transients still seem slightly rolled off to me, which can be relaxing, but also takes some of the excitement out of certain recordings, especially with guitars. When I used the iFi micro iDSD as a DAC (i.e. single ended), THX as the amp, and using a single ended cable for my Ether C Flow, I was not happy with the sound. The balanced output with the same DAC and headphones was solid. I have to use it more with my other headphones, I did like what it did to my Focal Listen (single ended only), though I mainly use them straight out of my phone, so any proper amp might impress me with them.

I find it concerning that the THX amp's manual states this:

That makes proper A/B-ing (with level matching) very tedious at best. It's also very easy to forget. And I can still just barely hear some music playing with the volume all the way down (balanced in, balanced out, medium gain, Ether Flow). Luckily, it has survived all my mishaps so far.

Thank you for the explanation.

Reasoning behind the power down rule could be an effort to avoid causing any shorts with 1/4 inch plugs. I've heard stories that this happening to people.

By the way, I apologize to everyone for the typo. "Can you to prove some insight?" What the hell was I thinking? lol
 
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Oct 31, 2018 at 3:15 AM Post #207 of 2,613
Reasoning behind the power down rule could be an effort to avoid causing any shorts with 1/4 inch plugs. I've heard stories that this happening to people.
That I could understand, but XLR does not have that problem, yet it's not called out as unproblematic. I suppose in regular use it's not too big a deal, but still risky given how many amps handle this just fine, and old habits die hard.
 
Oct 31, 2018 at 3:47 AM Post #208 of 2,613
Booring shopping question. Just curious if any EU customers got their yet? Seems to be boat shopping from germany?
 
Oct 31, 2018 at 11:10 AM Post #209 of 2,613
That I could understand, but XLR does not have that problem, yet it's not called out as unproblematic. I suppose in regular use it's not too big a deal, but still risky given how many amps handle this just fine, and old habits die hard.

Yes it's no problem to hot plug/unplug 789's XLR-4 headphone cables.

We recommend pausing the audio whenever plug/unplug 1/4" and 3.5mm TRS since they short T-R or R-S every time a user plugs/unplugs. Due to AAA's miniscule output impedance ~65 mOhms, even a tiny audio signal can cause full current >1A to flow through the short which trips the overcurrent protection, shutting the amp down for a few seconds before auto-rebooting.

Conventional amps with 1-10 Ohm or higher output impedance don't face this problem. Their output impedance limits the current. But of course, Zout > 1 Ohm isn't optimal for fidelity.
 

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