My first build

[paggerman]

Hello everyone, well, thanks to all the advice that i have read on this forum and making some stuff up as I went along, I have completed my first build. It's been about 3 months in the making, but one of those months was spent overseas. I finished the soldering last night and tested this morning using an 20 year old $10 analogue MM. Using the knowledge that I have garnered from this site (you can do it properly or close enough is good enough) all readings were within range - sort of. So I plugged in and waddaya know - complaints from household members. It works! There's a bit of buzz (probably heater cable dressing that can be fixed) and all the pots are wired back to front (the schematic didn't indicate pot pin numbers) but that's what I call character. What does it sound like? dunno. haven't got much of a reference (I find it much easier to build a valve amp than learn to play properly) and the speaker is salvaged from a Kawai organ and is free standing at the moment. Some pictures and schematics attached! Cheers everybody - thanks so much for all your help, entertainment and insight. I'll be watching. Particular thanks (in no particular order) to Enzo, Loudthud, Bruce, Steve Conner, RWood, Tubeswell, RG, JRFrond etc etc. My next project is going to be converting an old phonogram into an amp as per Dynaco's AA4 and RWoods' guidance.

[booj]

Chassis looks cool. Is it a baking pan?

[paggerman]

Hi Booj, yes it is a roasting (baking) pan. It's from Ikea and cost around AUD25. It does look pretty neat, but be warned - it's made of stainless steel and it takes a lot of drill and file work to cut the holes. Since embarking on my first build, I have discovered that valve radiogram chassis are fairly readily available (sometimes with some funny wooden stuff around them) for less than the cost of the roasting pan. the bonus is that they come pre-formed, pre-drilled and usually include some valves, a PT and OPT or two. They also come with a bunch of greasy old caps and resistors which may or may not be usable. Cheers!

[kg6epv]

That is cool! Different!

[Wombaticus]

I'm glad to hear that it works OK, so congratulations are in order! However, I'm quite concerned at the moment that the amp as constructed is a serious electrocution hazard. You need to generally tidy up the wiring in a big way, and make sure at the very least that the big electrolytic cap that is floating around free is properly secured. Also, it's very very important the mains safety ground have its very own strong attachment point - a dedicated bolt with a safety washers nearby to where the IEC socket enters the chassis. There are likely to be other issues too. I don't recommend that you continue to play it in its current state.

[paggerman]

risk mitigation

I'm glad to hear that it works OK, so congratulations are in order! However, I'm quite concerned at the moment that the amp as constructed is a serious electrocution hazard. You need to generally tidy up the wiring in a big way, and make sure at the very least that the big electrolytic cap that is floating around free is properly secured. Also, it's very very important the mains safety ground have its very own strong attachment point - a dedicated bolt with a safety washers nearby to where the IEC socket enters the chassis. There are likely to be other issues too. I don't recommend that you continue to play it in its current state.

Thank you for your concern. What you can't see from the photo is that the big 'lytic is secured using Scotch double sided foam tape (as are the other 6 big caps). And since taking those photos I have relocated the mains earth to its own tag (the one with a mounting bolt and star washer) on the tag strip about 4cm from the IEC. This action was taken as a result of reading Merlin's pages on grounding schemes.

I agree with your tidy up comment. My subsequent builds - which have been little SE amps built from salvaged radios - have been much tidier as I have learnt more and gained experience. This amp deserves a revisit before I put it into the cabinet I have in mind for it.

Thank you.