the modder 's diary part 14 1/2:
instead of testing my latest tube section i today reassembled the tu-05 to after a long time enjoy the quality of this amp and listen to some music.
i tried to drill some larger holes into aluminium, but my home equipment is much to light to do that. trying to drill a hole larger than about 10 mm (aluminium 3-4mm thick) will result in resonances of the bench drill and drill, the result is not a hole but something like modern art.
so no aluminium base for the tu-05.
but nevertheless i took the chance to
- completely recable the existing tu-05 using LCOFC copper wires and cables
- improve ground and the ground lines
- improve shielding of the different signals from each other
- implementing a center ground and protective ground
i implemented this using an idea i had for the build of my medium and high end versions to shield the wires and signals not only with the cable shield but using brass tubes as channel for the signal wires with the brass tubes connected to protective ground:
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This is the input cable (4 wire lcofc copper left/right/GND/GND twisted pair with shield) and the brass tube i cut to fit the size needed to be mounted on one side of the tube section providing one hole for the left channel wires:
i soldered the cable shield to the brass tube so after connecting the brass tube to protective ground you have an excellent shielded input path with signal ground for both channels (of course this is no double mono amp, but it's always good to have as much ground lines as signals).
here you also can see the brass tube i cut for the filament / heater cables switch (power save / 1s4 compatibility):
in a specific way it looks more like a detonator than an input cable :-).
here you see the output side of the tu-05 where i used 4 lcofc speaker wires (2.5mm diameter each):
the small black box (not blackbox) is the bias battery i mounted directly on the tube section as near as possible to reduce cable length.
here you see the two brass tubes mounted, on top the filament power wires shielding tube. i soldered both tubes to the main ground line, so the two tubes and the ground line together form one single large center ground:
as i had to put the cables into the tubes before soldering, the result looks not that professional, but didn't want to damage the wires with too much heat:
another benefit is that the tubes hold the cables in place, so much more stable than just soldered, no chance of cable break near the soldering points now.
at the moment i am listening to pink floyd - the wall - with the colorfly c4 using my grado style headphone and the tango output transformers connected to the tu-05.
sound? as far as i remember (if i can remember) - i have the feeling that especially the bass texture, depth and impact is improved, also there is so much air around anything, so spacious, PRAT to use this abbreviation, precision, bite, everything is there (have to report this to headphonia) (btw using the RFT DF97 / PHILCO 1S4 combo as usual).
sound seems slightly warmer, maybe due to the lcofc copper wires, as posted before i will use mundorf silver/gold wires for the df91 stages and lcofc copper for the dl92 stages in my final builds.
what a great amp.
Edited by GermanGuy - 1/1/14 at 3:51am