71A Direct Heat Triode Single End Class A Amplifier - Page 3 - diyAudio
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Old 7th May 2010, 01:29 PM   #21
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Hello,

The 7W is the output power of the outpout transformer of 71A SE. The output power of 71A single end class A is 0.8W.

I feel the sound of this low powered directly heated triode, 71A is so musical, smooth and a bit slow like listening to LP. This should be a kind of vintage sound of tube amplifier.

Thanks.
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Old 12th May 2010, 03:11 PM   #22
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The vintage Cornell Dubilier Flat Pack 270MFD /420VDC capacitor was used on power filter.
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File Type: jpg 71A-35.jpg (814.6 KB, 392 views)
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Old 28th May 2010, 03:33 PM   #23
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The input selector is from Noble, Japan.
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Old 21st July 2010, 02:20 PM   #24
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A new 71A amplifier is being made for a local customer. The circuit is same as the first one, 6SL7-71A class A single end with 5Y3 rectifier.
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File Type: jpg 71ASE-2-1.jpg (42.5 KB, 317 views)
File Type: jpg 71ASE-2-2.jpg (47.3 KB, 314 views)
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Old 21st July 2010, 03:08 PM   #25
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The power transformer, output transformers and choke are made in Hong Kong.
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Old 21st July 2010, 04:12 PM   #26
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The 120VA power transformer was particularly produced for the 71ASE. The core is H14 EI96x32.
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File Type: jpg DSCN2624.jpg (822.1 KB, 15 views)
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Old 21st July 2010, 04:17 PM   #27
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The craftsmanship of the power transformer from Po Shan is good.
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File Type: jpg DSCN2626.jpg (809.7 KB, 12 views)
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Old 21st July 2010, 05:07 PM   #28
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These are 15W output transformers made for 71A single end. Primary impedance is 4.8K ohms and secondary is 4 ohms and 8 ohms. The EI core is Z11 0.35 mm in size 76x26mm.
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File Type: jpg DSCN2616.jpg (806.2 KB, 28 views)
File Type: jpg DSCN2617.jpg (808.1 KB, 42 views)
File Type: jpg DSCN2618.jpg (783.1 KB, 35 views)
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Old 23rd July 2010, 02:38 PM   #29
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Install the output transformers onto the 71A amp.
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File Type: jpg 71A-opt-3.jpg (808.1 KB, 22 views)
File Type: jpg 71A-opt-6.jpg (798.7 KB, 21 views)
File Type: jpg 71A-2-13.jpg (824.7 KB, 37 views)
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Old 23rd July 2010, 03:21 PM   #30
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The power transformer fits the 71A amp.
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File Type: jpg 71A-2-08.jpg (791.0 KB, 36 views)
File Type: jpg 71A-2-09.jpg (760.9 KB, 23 views)
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