At the time of writing this kit form valve based
phono preamp for MM had not been released. I was invited by
Branko of
Oatley Electronics to help put the finishing touches on his latest kit. After the replacement of four small caps the
phono preamp was sounding very good. This kit would couple well with the K272A tube preamp.
The kit employs a switch mode 5V wall wart to power it. The beauty of this kit is the wall wart comes with auto mains AC voltage sensing and multiple international mains adapters. So no matter which country you are in the world you can
plug this kit straight into
the wall.
Inside the 5V is converted to 30V with yet another
SMPS. Not to worry
Branko has gone to a lot of trouble to ensure that no SM hash reaches the sensitive
ccts. To produce a
truly linear output the tiny JAN6418 valves had to run on 30V. Not only that valves are operating in
pentode mode. How may
phono preamp kits do you know are using
pentodes? This kit is a first on two very distinct fronts. Firstly a
truly international mains power supply and a two stage
pentode phono preamp.
But wait there is more: Each tubes stage is buffered by low noise
FETs. This
phono preamp would have to be one of the strangest ever.
Pentodes,
FETs,
SMPS, international SM wall warts. And it sounds so good.
The kit is complete and comes with very standard
componentry. If you are a first time builder don't change a thing. The more experienced constructor may swap-out some of the
components for more high-end parts. But isn't this the great thing about
inexpensive kits that you can put your own signature on the build. Try the kit if you have an analogue system (
TT) and see if you are not very impressed by the
quality of the kit and it's performance.
The
cct.
brds. are solder masked and the
brd. plated through. Most of the
cct.
brd. is earth plate. This keeps noise extremely low. Apart from a small
amount of valve hiss the board is dead quiet. At one meter from the speakers (and mine are 91db
sensitive) no noise can be heard.
The
enclosure is a double layer of Hammered Copper epoxy
enamel paint. A layer of
bituminous heavy Al foil lines the base and lid for enclosure dampening and
additional shielding. Gold plated
isolated RCA connections are on the back with the power socket. Tightly twisted telephone wire is used
for the internal hook-up. Why telephone wire? One it is a very pure copper and two it is single stranded. Tightly twisted: noise is locked out with no shielding capacitive issues. The feet are small rubber finished types, cheap but nicely
isolate. A rubber seal is clamped between lid and
enclosure to provide even more
resonance deadening.
The sound is excellent.
