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Xduoo Amplifiers
Dec 16, 2016 at 2:41 AM Post #77 of 1,985
plainbriny said:
   
Direct drop in is not likely.. the pins are different.
You need at least an adapter to convert the pins, but even so I am not sure whether the circuit will be compatible.
Click to expand...

 
I have them side by side and the spacing of the pins is exact same... hmm :/
 
Dec 16, 2016 at 2:56 AM Post #78 of 1,985
pin number and spacing are the same, but the spec are different.
 
12au7:
1: plate 2
2: grid 2
3: cathode 2
4: heater (+)
5: heater (+)
6: plate 1
7: grid 1
8: cathode 1
9: heater center-tap (ground)
 
6922:
1: plate 2
2: grid 2
3: cathode 2
4: heater (ground)
5: heater (+)
6: plate 1
7: grid 1
8: cathode 1
9: internal shield (N)
 
pin 4 and pin 9 are different.
 
Also, heater voltage for 12AU7 is 12V (series) or 6V (parallel), while 6922 is 6.3V.
 
I am not sure whether it will work. I know there's adapter to use 12AU7 in place of 6922, because 12AU7 can use 6.3 V designed for 6922. But I don't know whether the reverse is possible, since the circuit might provide 12V or 6V, and it will depend on the circuit design. An adapter might work (6V parallel) or might not work (12V series).
 
Dec 16, 2016 at 3:05 AM Post #79 of 1,985
plainbriny said:
  pin number and spacing are the same, but the spec are different.
 
12au7:
1: plate 2
2: grid 2
3: cathode 2
4: heater (+)
5: heater (+)
6: plate 1
7: grid 1
8: cathode 1
9: heater center-tap (ground)
 
6922:
1: plate 2
2: grid 2
3: cathode 2
4: heater (ground)
5: heater (+)
6: plate 1
7: grid 1
8: cathode 1
9: internal shield (N)
 
pin 4 and pin 9 are different.
 
Also, heater voltage for 12AU7 is 12V (series) or 6V (parallel), while 6922 is 6.3V.
 
I am not sure whether it will work. I know there's adapter to use 12AU7 in place of 6922, but I don't know whether the reverse is possible.
Click to expand...

I see, noted, thanks! ^^
 
Aug 8, 2017 at 4:35 AM Post #81 of 1,985
The new balanced tube amp finally arrived, in black or red color.

https://www.aliexpress.com/store/pr...-Headphone-amplifier/2718009_32827387939.html

2017-New-arrival-XDUOO-TA-20-High-Performance-Balanced-Tube-Headphone-amplifier.jpg
HTB1Bl2uSFXXXXbvXFXXq6xXFXXXh.jpg
 
Aug 26, 2017 at 10:03 PM Post #84 of 1,985
The new TA-20 looks interesting, anyone have more details on the architecture/design or sound?

I've had the TA-3 for several months now and can say for higher impedance cans it is fantastic. However, it definitely needed a 12AU7 replacement to sound it's best. I put a Japanese Baldwin (mullard design) tube and it's amazing with HD800. The warmth and more up front presentation is a great compliment to balance out the cool and wide balance of the cans, I'm blown away for the price.

Did try to change the 6P19 tubes, those are interesting. After buying about 10 on eBay, I could only find about 3 that were not micro phonic. However, the two Russian brands available sounded pretty much the same, and the stock Chinese tubes were pretty quiet anyway. The tube is a outstanding choice for an OTL amp, with a plate resistance Rp of about 100 ohms it's perfect for 300 to 600 ohm cans. I measured the output into 300 ohms and it managed 20V peak to peak, so that's some 2W into the HD800, which is double the allowed maximum. I'm listening to most stuff at 9 to 11 o clock on the volume knob. By 12 is starting to get uncomfortable and at 2o clock it takes your breath away (not listening volumes). Needless to say it drives them effortlessly!
 
Aug 27, 2017 at 3:07 PM Post #86 of 1,985
chillysalsa said:
The new TA-20 looks interesting, anyone have more details on the architecture/design or sound?

I've had the TA-3 for several months now and can say for higher impedance cans it is fantastic. However, it definitely needed a 12AU7 replacement to sound it's best. I put a Japanese Baldwin (mullard design) tube and it's amazing with HD800. The warmth and more up front presentation is a great compliment to balance out the cool and wide balance of the cans, I'm blown away for the price.

Did try to change the 6P19 tubes, those are interesting. After buying about 10 on eBay, I could only find about 3 that were not micro phonic. However, the two Russian brands available sounded pretty much the same, and the stock Chinese tubes were pretty quiet anyway. The tube is a outstanding choice for an OTL amp, with a plate resistance Rp of about 100 ohms it's perfect for 300 to 600 ohm cans. I measured the output into 300 ohms and it managed 20V peak to peak, so that's some 2W into the HD800, which is double the allowed maximum. I'm listening to most stuff at 9 to 11 o clock on the volume knob. By 12 is starting to get uncomfortable and at 2o clock it takes your breath away (not listening volumes). Needless to say it drives them effortlessly!
Click to expand...

On the subject of TA03, I personally like the stock tubes as they provide a really clear and pristine sound, which matches well with my HD600 and AKG K7XX. But I did try the bottlehead tubes and I liked the change in sound, so I may think of tube rolling again in the future.

I am getting the TA20 in for review and will post impressions and make a thread for it once I have it in my hand :) From what I understand, it is supposed to be a noticeable step up but I will withold personal judgement till I heard it for myself. I plan on using it with the balanced out of the Aune S6.
 
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