Guest Farnsbarns Posted August 14, 2013 Share Posted August 14, 2013 Looks like this on day one... Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted August 14, 2013 Share Posted August 14, 2013 I'm building a 2/9/18 watt amp based on 2 12ax7's 's and 2 EL84's. Hi/lo inputs. No gain control, no tone stack (although I might add one depending on how I get on with it), 2 direct line outputs. It will all be hand wired, point to point, on the turret board you see pictured. I have everything now except valves, wood and a speaker. Since those will be the last parts I decided to put that spend in another month. I should be able to beg, borrow or steel 2 EL84 valves and I've got old 12ax7s lying about that I can use for testing. I'll plug it all in to my Marshall cab for now, again, just for testing and to provide a load. Wish me luck! Link to comment Share on other sites More sharing options...
rct Posted August 14, 2013 Share Posted August 14, 2013 Luck! I get just a red x for the picture. rct Link to comment Share on other sites More sharing options...
BobF_ Posted August 14, 2013 Share Posted August 14, 2013 Good Luck! I hope the amp turns out better than the pic you posted ;) Link to comment Share on other sites More sharing options...
ZenKen Posted August 14, 2013 Share Posted August 14, 2013 Tough crowd Farns! We'll be following with great interest. Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted August 14, 2013 Share Posted August 14, 2013 Luck! I get just a red x for the picture. rct Oops, thanks, must use public link in future... Doh! Fixed... Link to comment Share on other sites More sharing options...
BobF_ Posted August 14, 2013 Share Posted August 14, 2013 Hey, NOW it looks pretty good! Link to comment Share on other sites More sharing options...
Rabs Posted August 14, 2013 Share Posted August 14, 2013 Nice one man.. will read with interest... Your amps, my guitars.. We could go into business ;) Good luck Link to comment Share on other sites More sharing options...
surfpup Posted August 14, 2013 Share Posted August 14, 2013 Sweet! Looking forward to following this project. Will it be one channel or two? You can voice those a bit like a Vox or more like a Marshall. Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted August 21, 2013 Share Posted August 21, 2013 Well, what should have taken a Couple of hours, max, has turned into a day. Anyone who read my other recent thread knows why. I got the layout done and soldered today... Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted August 21, 2013 Share Posted August 21, 2013 Damn it. Just noticed looking at the picture, one of my caps is backwards. That'll have to wait til tomorrow now. Link to comment Share on other sites More sharing options...
Riffster Posted August 21, 2013 Share Posted August 21, 2013 That looks very neat. Link to comment Share on other sites More sharing options...
Pin Posted August 21, 2013 Share Posted August 21, 2013 Valve or solid state Rectifier Farns? Or both? Link to comment Share on other sites More sharing options...
Rabs Posted August 21, 2013 Share Posted August 21, 2013 Well, what should have taken a Couple of hours, max, has turned into a day. Anyone who read my other recent thread knows why. I got the layout done and soldered today... Well I know VERY little about amp electronics so it looks good to me :) And good on you for keeping going despite whats happened. Allow yourself the proper tine to get better but in the meantime you are only on your own schedule so like my build, slow but sure is the way. Keep it up :) Link to comment Share on other sites More sharing options...
badbluesplayer Posted August 21, 2013 Share Posted August 21, 2013 Damn it. Just noticed looking at the picture, one of my caps is backwards. That'll have to wait til tomorrow now. We noticed that! Link to comment Share on other sites More sharing options...
badbluesplayer Posted August 21, 2013 Share Posted August 21, 2013 Damn it. Just noticed looking at the picture, one of my caps is backwards. That'll have to wait til tomorrow now. We noticed that! Link to comment Share on other sites More sharing options...
btoth76 Posted August 21, 2013 Share Posted August 21, 2013 Hello Farnsbarns! Very nicely organized, clean board. Congratulations! Here are my amps of the same construction: One of them has a valve rectifier, the other has a diode in place. Since both have the rectifier valve installed (in one of them for decorative purposes only), I can't tell them from each other. Cheers... Bence Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted August 21, 2013 Share Posted August 21, 2013 Valve or solid state Rectifier Farns? Or both? See the far right of the board, there's 4 diodes which is the rectifier part of the circuit. Because this will be a low powered amp you don't want the voltage sags that you can get with a valve rectifier. Basically, I'm keeping it simple, that's the name of the game here. Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted August 21, 2013 Share Posted August 21, 2013 We noticed that! Well, you would, as would anyone who knew what they were looking at. That fat electrolytic with the arrows pointing up at the positive line sticks out a bit. I've desoldered it and turned it round now. Electrolytic cap explosion averted. Didn't end up messy either. I already had to turn a diode round. I look at a component, work out where I want it and which way, then I bend and trim the legs, forget it has polarity and solder it in. Actually, I'm surprised I only made 2 mistakes. Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted August 21, 2013 Share Posted August 21, 2013 The next step is to work out all the wire lengths to be soldered to the underside of the board. To do that I had to build the chassis. Simple stuff, just nuts and bolts, but because the chassis is generic I have to work out the tidiest layout. Here it is... The out side... No prizes for working out where the transformers were made! Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted August 21, 2013 Share Posted August 21, 2013 And the inside... Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted August 21, 2013 Share Posted August 21, 2013 And this is where the board will sit.... Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted August 21, 2013 Share Posted August 21, 2013 There are a couple of issues coming to light. One, the jack sockets, front and rear, are designed for a thicker material and never fully tighten. Going to have to find some suitable washers, no biggie. Two, the rotary switch I got for the power switching has come with absolutely no documentation on pin outs. Some trial and error with a multimeter is in my future. Link to comment Share on other sites More sharing options...
Guest Farnsbarns Posted August 22, 2013 Share Posted August 22, 2013 Hmm, beginning to wonder if anyone is actually interested. Ho hum, I've started so I'll finish. Having looseley assembled the chassis I decided to wire the valve sockets for heating, I need to keep this wiring away from signal carrying wires so it made sense to have it in before I work on wire routes for everything else. To this end I have tucked it all away at the back.... This all comes off a 6.3v section of the power transformer. First it goes to the two power valves and then the 2 preamp valves. The pin outs are different for each but essentially both types need the same voltage, just to different pins, therefore I can piggy back each connection off the last. Polarity doesn't matter either so all green wire. I've twisted these in opposing pairs which helps to keep things tidy but also each pair should cancel out each others magnetic fields. Link to comment Share on other sites More sharing options...
capmaster Posted August 22, 2013 Share Posted August 22, 2013 I'm building a 2/9/18 watt amp based on 2 12ax7's 's and 2 EL84's. Hi/lo inputs. No gain control, no tone stack (although I might add one depending on how I get on with it), 2 direct line outputs. It will all be hand wired, point to point, on the turret board you see pictured. I have everything now except valves, wood and a speaker. Since those will be the last parts I decided to put that spend in another month. I should be able to beg, borrow or steel 2 EL84 valves and I've got old 12ax7s lying about that I can use for testing. I'll plug it all in to my Marshall cab for now, again, just for testing and to provide a load. Wish me luck! Often the old 12AX7s are the better... I would rather sacrifice new ones ;) All kidding aside, looks good to me, and to add a tone control shouldn't be a problem if there's enough makeup gain left in the circuit. Did you plan three preamp stages and a single-triode phase invertor/driver stage, ot two preamp triodes and a double-triode balanced driver? Link to comment Share on other sites More sharing options...
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