I've basically finished the case - it's sanded back to bare wood & I've put several coats of furniture wax on. The result is smooth wood and a beautiful lustre, especially under natural light. I'll post some photos as soon as there's a nice sunny day to take them.
On the electronics front, less success. After soldering all the resistors in the amplifier kit to the board, I learned why one should always read instructions in full before starting work on a kit. Two of the resistors - 1 and 3W metal oxide - had to be mounted off the board as they generate a lot of heat in operation. Annoyingly, by the time I discovered this, I'd already trimmed the leads.
So, construction is stalled until I get my hands on some replacements. Dick Smith didn't have any; they have in fact all but given up on hobbyists, preferring to focus on retail appliances. That's a shame, as my introduction to electronics was courtesy their Funway series. Anyway, I found an online retailer called RS Components, who stock a much wider range of components.
However, they only stock 330ohm resistors of the type I need, rather than the 300ohm specified in the kit. I've emailed S5 to ask whether 330ohm would be acceptably close, given the broad tolerances of the 3W resistors being used, and will be ordering what I need as soon as I hear from them.
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2 comments:
If necessary you could parallel a 330 ohm with a 3.3k ohm resistor. That nails the 300 ohm spec. (And since the power dissipation varies as 1/R, the piggy-back 3.3k resister only needs to be rated at a tenth of the power. A half-watt resistor will do.) It's a bit ugly soldering on piggy-back resistors, though.
Jaycar electronics (corner of Springvale road and Princes highway http://www.jaycar.com.au/ ) has a better range of hobbyist stuff than Dick Smith, but not as good as RS and still won't stock the resistors you want.
Thanks - that'd be a good approach (& to my shame, one I didn't initially think of) but for the fact that the amp is going to be on display - the plan is to have the hinging door open to reveal the amp side-lit & mounted on a nicely polished pine baseboard.
Fortunately, I received a nice prompt response from S5 to say that the 330 can be subbed in. According to them, the only effect would be a 1/2dB drop in volume with the amp at max output, which I'm quite happy to accept.
I've had a look on the RS website, & discovered that they only sell resistors (at least of the type in which I'm interested) in lots of 10 - meaning around AUD$14 + shipping for three resistors :-O
So I fired Jaycar an email asking if there's any way they could order in what I need. Pigs, fly, etc. but it's worth a shot. Failing that I'll just have to swallow my pride & order 30 resistors from RS.
In other news, if you or any other reader here has a need for such resistors I'll have a bunch spare that I'm happy to let go for free (or the cost of postage where appropriate) :-)
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