Review and Measurements of Massdrop THX AAA 789 Amp

[f78fk]

Well, I missed the price of $199. If THX AAA 789 Amp is priced at US$199, can Everybody notify me by email?
Email: [email protected]

 

[AVKS]

Well, I missed the price of $199. If THX AAA 789 Amp is priced at US$199, can Everybody notify me by email?
Email: [email protected]

It's still worth the current $239. Not sure of your situation of course but if you need an amp, the extra $40 means you get to enjoy it now (or mich sooner) than you would otherwise by waiting for the $199 that may or may not come back around.

 

[f78fk]

It's still worth the current $239. Not sure of your situation of course but if you need an amp, the extra $40 means you get to enjoy it now (or mich sooner) than you would otherwise by waiting for the $199 that may or may not come back around.

I currently live in China, so I need an additional $60 transshipment and $30 tariff. I want to spend as little money as possible to get it.

 

[f78fk]

Thx AAA 789 and SH-9 have almost the same price in China, about $280.
My headphones are dt880 250O and AKG K702. Should I choose thx aaa789 or SH-9 without considering the price?

 

[RickSanchez]

Thx AAA 789 and SH-9 have almost the same price in China, about $280.
My headphones are dt880 250O and AKG K702. Should I choose thx aaa789 or SH-9 without considering the price?

You may want to start a new thread asking for recommendations since you're asking about the SMSL SH-9.

Other than that I suggest you carefully read Amir's reviews for both the 789 and the SH-9. Then review the features of each device: THX 789 | SH-9. I think your decision will ultimately come down to the features you want/need as both amps are transparent and have plenty of power. One (possible) advantage of the THX 789 is the balanced out; it appears the XLR out of the SH-9 is not balanced.

 

[dsnyder0cnn]

Well, I missed the price of $199. If THX AAA 789 Amp is priced at US$199, can Everybody notify me by email?
Email: [email protected]

When I talked to them about my replacement, they said that stock is low. If you want one, now is the time.

 

[Jimbob54]

When I talked to them about my replacement, they said that stock is low. If you want one, now is the time.

Ditto. Mine arrived, power pack was faulty and it was RMAd but they said low stock.

 

[f78fk]

When I talked to them about my replacement, they said that stock is low. If you want one, now is the time.

I just bought thx AAA 789 amp for $239. Thank you.

 

[dsnyder0cnn]

I just bought thx AAA 789 amp for $239. Thank you.

Congrats! Enjoy

 

[vaidd]

Hi THX AAA 789 owners…I've had my amp for nearly a year and still love it. Sadly, I've started to hear quite a bit of static when making volume adjustments. It started in the left channel, but now I'm hearing it in both. I have not observed significant channel imbalance issues once I settle on a volume setting, but the increasing static is disconcerting.

I have tried just working the volume knob back and forth, and with enough rotations, that seems to reduce the static. However, when I come back to the amp the next day, the static is back. I've reached out to Drop support to see if this is covered under warranty. I could easily buy another unit (missed the $199 sale, but the $239 price is still great). However, if this issue is a design flaw that affects many units, I may find myself in the same situation 8-12 months from now.

I'd love to get a sense from this community about how common this issue is. I'm not using my amp in a particularly dusty environment, but even if I were, I'd expect the pot to be sufficiently sealed to protect itself. This is my only gripe with this amp. It's a lovely piece that's destined to become a classic…assuming a noisy pot does not spoil it. Thanks.

I had the exact same problem on mine and it started last week, a little over a year of ownership and out of warranty. The volume knob itself felt smooth, but I heard crackling/static in my headphones during adjustment. I was able to fix it with CRC QD Contact Cleaner and CRC 2-26 Multi-Purpose Lubricant. I think you can also use some products from DeoxIT but CRC's products were available to me immediately.

CRC QD Contact Cleaner: https://www.homedepot.com/p/CRC-QD-11-oz-Contact-Cleaner-02130-6/202262505

CRC 2-26 Multi-Purpose Lubricant: https://www.homedepot.com/p/CRC-2-26-5-oz-Multi-Purpose-Lubricant-02004/100398344

I removed the screws in the back and the one screw in the bottom, removed the back cover, and then slid the front cover + PCB out the front. Using a paper towel, I covered the entire PCB except for the pot, sprayed the cleaner where the pot meets the front cover on the inside and where the knob meets the front cover on the outside. Then, I turned the pot from minimum to maximum multiple times. I repeated this spraying and turning process three times and then dried the excess cleaner with a paper towel. I waited 10 minutes for it to fully dry. I put the 789 on its front cover and added one spray of lubricant to the recess that surrounds pot where it meets the front cover, then turned the pot from minimum to maximum multiple times. Do not add too much lubricant since it makes the knob too easy to turn, and you'll have to re-clean the pot with the cleaner.

I hope this information is helpful in case it happens again (outside warranty) or to anyone that stumbles upon this thread.

 

[dsnyder0cnn]

I had the exact same problem on mine and it started last week, a little over a year of ownership and out of warranty. The volume knob itself felt smooth, but I heard crackling/static in my headphones during adjustment. I was able to fix it with CRC QD Contact Cleaner and CRC 2-26 Multi-Purpose Lubricant. I think you can also use some products from DeoxIT but CRC's products were available to me immediately.

CRC QD Contact Cleaner: https://www.homedepot.com/p/CRC-QD-11-oz-Contact-Cleaner-02130-6/202262505

CRC 2-26 Multi-Purpose Lubricant: https://www.homedepot.com/p/CRC-2-26-5-oz-Multi-Purpose-Lubricant-02004/100398344

I removed the screws in the back and the one screw in the bottom, removed the back cover, and then slid the front cover + PCB out the front. Using a paper towel, I covered the entire PCB except for the pot, sprayed the cleaner where the pot meets the front cover on the inside and where the knob meets the front cover on the outside. Then, I turned the pot from minimum to maximum multiple times. I repeated this spraying and turning process three times and then dried the excess cleaner with a paper towel. I waited 10 minutes for it to fully dry. I put the 789 on its front cover and added one spray of lubricant to the recess that surrounds pot where it meets the front cover, then turned the pot from minimum to maximum multiple times. Do not add too much lubricant since it makes the knob too easy to turn, and you'll have to re-clean the pot with the cleaner.

I hope this information is helpful in case it happens again (outside warranty) or to anyone that stumbles upon this thread.

Very helpful. Thanks!

 

[f78fk]

I had the exact same problem on mine and it started last week, a little over a year of ownership and out of warranty. The volume knob itself felt smooth, but I heard crackling/static in my headphones during adjustment. I was able to fix it with CRC QD Contact Cleaner and CRC 2-26 Multi-Purpose Lubricant. I think you can also use some products from DeoxIT but CRC's products were available to me immediately.

CRC QD Contact Cleaner: https://www.homedepot.com/p/CRC-QD-11-oz-Contact-Cleaner-02130-6/202262505

I had the exact same problem on mine and it started last week, a little over a year of ownership and out of warranty. The volume knob itself felt smooth, but I heard crackling/static in my headphones during adjustment. I was able to fix it with CRC QD Contact Cleaner and CRC 2-26 Multi-Purpose Lubricant. I think you can also use some products from DeoxIT but CRC's products were available to me immediately.

CRC QD Contact Cleaner: https://www.homedepot.com/p/CRC-QD-11-oz-Contact-Cleaner-02130-6/202262505

CRC 2-26 Multi-Purpose Lubricant: https://www.homedepot.com/p/CRC-2-26-5-oz-Multi-Purpose-Lubricant-02004/100398344

I removed the screws in the back and the one screw in the bottom, removed the back cover, and then slid the front cover + PCB out the front. Using a paper towel, I covered the entire PCB except for the pot, sprayed the cleaner where the pot meets the front cover on the inside and where the knob meets the front cover on the outside. Then, I turned the pot from minimum to maximum multiple times. I repeated this spraying and turning process three times and then dried the excess cleaner with a paper towel. I waited 10 minutes for it to fully dry. I put the 789 on its front cover and added one spray of lubricant to the recess that surrounds pot where it meets the front cover, then turned the pot from minimum to maximum multiple times. Do not add too much lubricant since it makes the knob too easy to turn, and you'll have to re-clean the pot with the cleaner.

I hope this information is helpful in case it happens again (outside warranty) or to anyone that stumbles upon this thread.

CRC 2-26 Multi-Purpose Lubricant: https://www.homedepot.com/p/CRC-2-26-5-oz-Multi-Purpose-Lubricant-02004/100398344
I removed the screws in the back and the one screw in the bottom, removed the back cover, and then slid the front cover + PCB out the front. Using a paper towel, I covered the entire PCB except for the pot, sprayed the cleaner where the pot meets the front cover on the inside and where the knob meets the front cover on the outside. Then, I turned the pot from minimum to maximum multiple times. I repeated this spraying and turning process three times and then dried the excess cleaner with a paper towel. I waited 10 minutes for it to fully dry. I put the 789 on its front cover and added one spray of lubricant to the recess that surrounds pot where it meets the front cover, then turned the pot from minimum to maximum multiple times. Do not add too much lubricant since it makes the knob too easy to turn, and you'll have to re-clean the pot with the cleaner.

I hope this information is helpful in case it happens again (outside warranty) or to anyone that stumbles upon this thread.

I think it is better to replace the potentiometer, and it is best to buy the ALPS potentiometer.

 

[vaidd]

I think it is better to replace the potentiometer, and it is best to buy the ALPS potentiometer.

Have you found a suitable drop-in replacement for the potentiometer and knob? I think the knob is permanently attached to the potentiometer, so both components would have to be replaced.

 

[f78fk]

Have you found a suitable drop-in replacement for the potentiometer and knob? I think the knob is permanently attached to the potentiometer, so both components would have to be replaced.

MassDrop THX AAA 789 - Linear Headphone Amplifier

The 789 Potentiometer is cheap af, when I opened mine to check it was some knockoff Chinese brand trying to be Alps. I also had the same issue with the left channel being scratchy, and while the potentiometer IS desolderable, the damn volume knob is part of the pot, like it’s not one of those...

forum.hifiguides.com

Drop + THX AAA™ 789 Linear Amplifier Discussions | Drop | Does anyone have...

Does anyone have any experience with fixing it when the volume pot goes scratchy? I have one of the originals that say THX AAA 789 without the drop logo. Any...

drop.com

You are right. My aaa789 has just been shipped. I regret buying it a little.

 

[rtos]

I think it is better to replace the potentiometer, and it is best to buy the ALPS potentiometer.

I detest standard sliding potentiometers. They can exhibit imbalances between channels and often get noisy over time, and are an obvious potential weak spot in otherwise excellent amplifiers. It's a shame the AAA 789 didn't at least come with a better quality pot like the Alps, but this didn't prevent me from purchasing it. Instead of using the 789's built-in pot for volume control I set the pot to maximum and use a Nobsound/Yisheng relay-based switched attenuator/passive preamp (which uses 0.1% metal-film resistors) between my DAC and the 789. The Nobsound unit (https://www.aliexpress.com/item/32840083176.html) is a bit "wonky" at times (it occasionally makes mechanical noises that require a slight adjustment of the knob to stop, and sometimes doesn't engage when turned on), but for only about $150 I find it to be more than satisfactory.

 

[f78fk]

I detest standard sliding potentiometers. They can exhibit imbalances between channels and often get noisy over time, and are an obvious potential weak spot in otherwise excellent amplifiers. It's a shame the AAA 789 didn't at least come with a better quality pot like the Alps, but this didn't prevent me from purchasing it. Instead of using the 789's built-in pot for volume control I set the pot to maximum and use a Nobsound/Yisheng relay-based switched attenuator/passive preamp (which uses 0.1% metal-film resistors) between my DAC and the 789. The Nobsound unit (https://www.aliexpress.com/item/32840083176.html) is a bit "wonky" at times (it occasionally makes mechanical noises that require a slight adjustment of the knob to stop, and sometimes doesn't engage when turned on), but for only about $150 I find it to be more than satisfactory.

I plan to DIY use ALPS RK09L to replace it,It costs less than $5, I can directly rotate the metal rod to adjust the volume.I don't care about the appearance.
https://tech.alpsalpine.com/prod/e/html/potentiometer/rotarypotentiometers/rk09l/rk09l_list.html

 

[dsnyder0cnn]

I detest standard sliding potentiometers. They can exhibit imbalances between channels and often get noisy over time, and are an obvious potential weak spot in otherwise excellent amplifiers. It's a shame the AAA 789 didn't at least come with a better quality pot like the Alps, but this didn't prevent me from purchasing it. Instead of using the 789's built-in pot for volume control I set the pot to maximum and use a Nobsound/Yisheng relay-based switched attenuator/passive preamp (which uses 0.1% metal-film resistors) between my DAC and the 789. The Nobsound unit (https://www.aliexpress.com/item/32840083176.html) is a bit "wonky" at times (it occasionally makes mechanical noises that require a slight adjustment of the knob to stop, and sometimes doesn't engage when turned on), but for only about $150 I find it to be more than satisfactory.

Yes. For my listening tests, comparing the Topping D90SE and Gustard X16, I set the volume on my THX AAA 789 to maximum and used my Topping Pre90/Ext90 analog preamp to control volume. The THX AAA 789 very quiet, even with the volume set to max, so this did not add audible noise to my test rig.

My replacement THX AAA 789 is on the way. Looking forward to another 9 - 13 months of trouble-free use before I have to start cleaning the volume pot. For the price paid, this is acceptable, if not ideal. Beats the heck out of spending 10x more for a Benchmark HPA4 with only marginally better performance and the same or less output power.

 

[cubanmetalguy]

I bought my THX AAA 789 back in September 2019 and it has been running 24/7 with no issues at all. Paid $400 for it.

 

[Rottmannash]

I bought my THX AAA 789 back in September 2019 and it has been running 24/7 with no issues at all. Paid $400 for it.

Same here. Flawless performance.

 

[John B]

I max the volume and run digital volume control through J river to attenuate.