Wow - managed
to start this month before it finished.... however,
with the going's on from last month on the job front,
the car is still taking a back seat - if it had one.
Mandy does have a couple of interested parties, my
favorite being from an engine tuner/restorer/supplier.
It would be great and after a couple of months I might
have to twist her arm to get a club area visit arranged.
We;ll see how things go.
April - Valve Amp
Today was a good
day. I managed to build up enough enthusiasm to make
a start on a new board and duly sat in front of the
F1 qualifying to get it finished. Not only did I do
that but Jenson Button got his first ever pole for
the BAR team.
I took it out to the garage where I had the amp hooked
up to my tape deck and some very naff speakers for
testing. The new board was transplanted and I took
the opportunity to fit new silicone components at
the same time (regulator and Fet) just for good measure.
At the first power up, it was obvious before I put
the meter on it that all was well. The Led's are meant
to gradually come up to brightness as the power builds,
and whereas before the left channel would come on
fully bright, it now built up over the predetermined
12 seconds or so. The board gave a nice rock steady
supply of 462v which matches the original side and
it sounded good.
A slight humm is audible as the power comes up from
about 100v onwards, but this dies away as it gets
to the full voltage and it isn't audible unless your
ear is up against the speaker, so I shall not worry
to much about that.
I then spent a while gluing in some supports so that
the signal wires could be kept tidy and I also shortened
these down to the correct length. I swapped in two
new blue Led's which give a nicer glow than the red's
I had before and look a bit 'cooler' - well, different
at any rate, most Hi-Fi have red, so better to be
different. Maybe I should have gone for Red and Green,
for Port (left hand) and Starboard (right hand)...
na, now don't get silly.
Can't wait to have the space to hook it up to the
decent speakers indoors and the CD player - although
I don't think it is good enough for it, but will have
to do for the foreseeable future.
March to 19th April - Valve Amp
To help take
my mind off things, I've gotten back into the valve
amp project that Steve F and I started a long time
ago (June 2002 if you must know!). Steve finished
his quickly - the benefit of working with the guy
who designed it. I wasn't quick enough and when they
parted company - literally - mine started collecting
dust. Well, after some gentle hassling from Steve,
we got together one Sunday morning and I got a few
more things sorted out. I had actually done nearly
all the wiring, it was just the final few things like
connecting the power board up, etc.
We braved it and connected it up in his garage and
on an old pair of speakers it made it's first noises.
Not for too long though as it dropped out after a
short while and didn't have any power/depth to the
sound. As neither of us are electrical bods, we called
it a day and Steve contacted another one of the amp
builders to see if he knew any more. Fortunately he
does and we arranged another meeting where we could
try to sort out his problems as well.
The problem with mine was eventually found to be lack
of power. With both channels running off of the same
power supply board, the amp would drop out as the
valves started pulling full voltage. By wiring one
channel at a time we proved that both worked perfectly
on their own and that an extra board was required.
Guess what I've been sorting out since then.....
I ordered the new parts, bought a new board and set
about making a copy of the original circuit. Unfortunately
when we came to test it out it was found that the
power was ramping straight up to the full voltage
of ~500v rather than steadily building. Having tried
changing components I decided that I should just start
again, this time with a proper circuit diagram.
I must get on with it - I want to set it up this weekend
on my good speakers!