Hi-Fi Tube Pre-amps Shootout Test: Nobsound Marantz 7 vs Shigeru Wada vs TP Audio

Please read the full description.
I am in the process of doing some changes in my Hi-Fi system. I did a test with 3 pre-amplifiers and I decided to share it. But first... what are pre-amplifiers and what are they meant to? Why vacuum tube pre-amplifiers? In this video a shootout and/or mini-review... as you wanna see it...

I used my 3 pre-amplifiers: hand built TP Audio, made in Italy and 2 NobSound preamps, they are a clone/variation of a Marantz 7 Pre-amplifier, made in China but using a lot of western components, one of them has the Shigeru Wada circuit. Typically chinese, they are made by BRZ Hi-Fi but rebranded "Nobsound". I have another piece of gear that is the same: it says Nobsound in the machine but BRZ Hi-Fi in the remote control...

I used only the best military tubes:
-Sylvania 5751 (ECC83/12AX7 with 30% less gain) [USA, 1977, Gold pins, one of the best 5751 ever made]
-Radio Technique 6189 [France, 1975, double getter support, made for aviation, one of the best ECC82/12AU7 ever made]
-Tung Sol 6X4W (note that, originally, the pre-amplifiers use a chinese 6Z4 but I used a converter) [USA, 1959, with black plates, square getter and a super sound]

Note that although I used always the same Sylvania 5751 tubes for amplification, the three pre-amplifiers have different circuits and use different tubes: for cathode follower and may have a tube rectifier or not. I used always the same tubes for rectification. Only the cathode follower tubes were different: Sylvania 5751 or RTC 6189.

Time Machine for this video:

00:00 Start
00:10 Pre-amplifiers?
04:42 Test Description
06:05 Sound Test
08:44 Conclusion


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