End of my frst foray into amp building: Tolexing and putting it together, the end result

Right, so last time I just had the tolexing left to do, and thanks to some sunny weather over the weekend it got done. I was dreading it, expecting it to go pretty wrong, but, as I discovered, it's actually fairly easy, well, easier than you'd imagine.

First up, you will need, some tolex, cut to be enough to wrap round the amp with some overhang. You will need spray glue (instant adhesive stuff that you spray, wait 2-3 minutes for it to go tacky and then stick) and an exacto/hobby knife, and, well, that's it.

Process is really easy too. Wrap it round the amp, line it up, then peel back, and just start doing each side. I could explain it, but this youtube video does a far better job of explaining it all, and is what I used as a guide. Also, it really is tre that the corners can be messy, mine weren't all that great, but the amp corners hide it all, so that really does make up for any slight miscuts you do.

The seem was also fairly easy, although next time I'd do it in the middle of the base of the amp, as doing it at the side was a little bit fiddly, or I'd at least line it up so it was exactly to one side, ie, the bottom fold just slots straight into the base of the cabinet. Anyway, lessons learnt.

And well, that's pretty much it. About 1-2 hours work in all, poke the holes for chassis mount, handle mount etc through with a small sharp thing, screw on the corners to hide any weirdness in the corners (ie, mistakes), add handle and done!

I also mounted the front grill to the head cabinet using screws on the side, which gives a cool look.

Anyway, after that, just a case of slotting in the amp, screwing it in via chassis mounting screws (which in my case double up as amp feet, which is pretty usefull) and voila, one finished amp! Looks pretty damn cool eh? Really glad I went with the snakeskin, it's a very cool look for a cool amp. Really pleased how it turned out, and now thinking of what I want to make next!

Avon Calling: Tarting up the amp

Made the grilles for the amp today, and they look pretty cool! Used my dremel with the discs that cut metal on a huge sheet I got during the week. The sheet of grille metal was about 1.2m by 2.4m, i really couldn't find anything smaller, and this was a decent enough price and leaves with enough material to make grills for at least another 6 amps, or god knows what else.

Anyway, after starting to cut it indoors and then being told that indoor fireworks and the possibility of setting fire to curtains etc was not a good idea (or furthermore permitted) I did the cutting outside. The dreme discs (456 something) don't last long, so I've ended up using about 10 of them or so to cut the sheet into 80x60cm chunks, and for cutting out the 3 grills, as am making one as an offering to the Oracle (Tony) for all his help.

The front grille i decided to mount onto the herad cabinet, so cut a chunk about 60mm wider than the width, and 1.5cm longer than the height. Then I bent the side and bottom (after cutting out two small squares at the bottom to allow this). The back is just one sheet, no bending, although I sort of wish I had, but, it's not like I don't have enough material to make another one if I am unhappy about it later down the line. Anyway, I think it looks pretty damn cool so far!

 I also mounted the handle, which is a nice faux leather one, which is much like the one I have on my Mesa Roadking (which is returning home soon). Need to drill the holes bigger for that, as I got some of those metal things you hammer in that add stability or make iit fasten better or something... I got those with a "genuine fender dogbone" handle, which unfortunately just looked plastic and had fender written on it, so no use for this project. Still, the screws + inserts that came with it worked with the faux leather handle, so all good.


So, all cut, mounted the wooden bits so the rear grille can be attached, and then got out the spray can like a good little delinquent and went to work.

Sprayed the inside of the cabinet first, this is so when I tolex it, if the tolex doesn't go all the way in, then there's a black coating to stop you seeing bare wood. Only needed one coat quickly, more wood be overkill, as would primer as this isn't really going to be visible unless you really really look hard. With a torch. And are obsessive about things to unhealthy extremes.

Then I did the grille for the oracle, about 2 coats each side of BMW 318 black I had left from an ill fated "paint you own headstock" thing I tried last year. Came out looking cool :)

Then I sprayed the grilles for mine, as well as the screws to attach the grilles as well. Oh, and also some screws which will be used to attach the black corners I have for the amp. COlour coordination. It's important. Really. Anyway, I figured instead of the hassle of painting them by hand (which I did for the screws inside the amp that are visible on the chassis) that it might be easier to screw them into some scrap wood, and just spray paint them. Much more efficient, and a hell of a lot faster, and I think it's also a more even finish on the screws. Still unsure as to whether I am going to strip the apint when screwing them onto their destination, but if so, i'll just repaint by hand.

Anyway, the only thing left to do pretty much now is tolexing, ie, time to dress it in it's clothes!

5150 Makeover - The Plan

So I have my trusty block letter 5150 I've had for years, sold once, and bought straight back (as I missed it) and it's now kind of being a bit neglected. What does that mean? Make over time of course!

It's already got a bias mod, so that's all god, but I'll be putting a choke in (just got a 10H one on order) and will be changing the power tube resistors to some nice chunky 470ohm ones (as I need to with the choke mod).

I'll also be trying out a few of the mods on this page:

Peavey 5150/6505 series mods

mainly shifting the mid control and also getting rid of some fizz by adding a 10pF cap across V5B and maybe some other "stuff"

Also I have some sexy tolex for it, but can't decide wther mesa style black taurus leather like, plain white, or carbon fibre will be the coolest, but that's something to decide later.

I'm also going to repaint the metal corner protectors as well and just in general spruce it up somewhat

Sloclone and the Sounds of Life, quick recordings done with the OD channel

Well, done a quick riff-o-rama and recorded it as a test, just as an example of one of the sounds this amp has! OD channel, gain on 3, TS808, eq all near the middle, presence and depth on 3.

Moving into a new undecorated home...

Quick post, not much to report other than did a test fit into the head cabinet Vyse Amps made for me, perfect fit, and also well cool that I can now actually put it on the amp stack and move it off my desk! Next will be adding feet and a carry handle, and then tolexing. I also need to find some cool metal grille material from somewhere as well...

 

Anyway, all looking and sounding good!

The Victory Dance

So when i first started this blog I said that it had always been an ambition of mine to build a tube amp, and about a month after starting the endeavour it is done and working. Literally the first thing I've built from basic electrical components in quite a while, and certainly the most complex for as long as I can remember.

It's been a journey across large component orders, tracking down chassis, having to order missing parts, learning how and how not to drill into metal, and a whole bunch of other stuff. I've understood some of the circuit parts and mods as well, although nowhere near as much as I'd have liked to as ended up doing more building that examining, but that's all down to excitement right?

So, since the last blog I literally just dremeled down the longer mid shaft (pictures are from before I did that) from the replacement pot and that's it, nothing else, as it's all working!

Anyway, the next thing on the todo list is to give this amp a home. I got back my headshell from Barry at Vyse Amps who has done an excellent job, and all it needs is for me to source so cool looking grills and learn how to tolex it with the tolex I ordered about 1-2 weeks ago and am waiting for. That should be fun.

In the end, here we have it, one fully functional but currently homeless Slo Clone, a 100w high gain beast of an amp. Awesome :)

Oh, almost forgot, how does it sound? Well, first off, this has more gain that I thought it would have, seriously. The crunch channel with the gain at 7-8 is a very very usable tight rhythm sound which is pretty damn awesome, so very pleased with that. The cleans are really nice as well, which I should have expected, but still is surprising, need to play around with a bit more on the clean/crunch channel because, well, been obsessed by the OD channel.

And boy does it deliver, thick brown soundy gain that is just awesome. It's not as tight as some of the modern high gain metal heads, instead having more of a rock vibe, but don't get me wrong, you could easily do metal with this and still beat the living hell out of most "metal" amps in terms of tone and aggression.However, we all know this amp is known as "the" lead amp, and well, it delivers in spades. It just has that rock n roll edge to it where the notes feel fluid and you feel like it's working with you when you're playing. Really like it.

The thing that makes it is the whole versatility. This amp can do a lot of things, and I am really happy I built it!

I know there's no clips etc yet, it's a bit difficult plugging it into my recording setup without it being homed in it's headshell so not been able to record with it and have had to run it through a hotplate into a cab to play it so far. Once it's homed however, it'll then be able to be put through it's paces, and I'll be able to get some recordings done.

But for now, I'm just well happy it's all working.

Oh, and somehow I do think I'll be modding it here and there, just simple ones to start with though, but still, there'll be mods :D. I also might do a little bit of tidying inside the chassis, but that's just to me more OCD about it.

oh, and shit eating grin? check, that's definitely there every time i see it or play through it!

Troubleshooting to Victory

Right, in my last post I had everything wired up ready to go, so, why no victory look at how awesome my first time skillz are etc etc post?

Because quite frankly it didn't work.

Let me set the scene, our hero, with confidence boosted by how nice it all looks and having caught a few errors here and there from the layout and fixing them, intrepidly surveys his work and in supreme confidence flicks the switch, guitar in hand, ready for the 80's montage with high fives, winks and other awesome poses.

Yeah, so you can guess how that turned out... cur long face, toys thrown out of the pram and infinite sadness. It just didn't work, no apparent sound at all, back to the drawing board time, or more specifically troubleshooting.

So, I started, first thing to check was whether I had wired up all the valves/controls properly, so I went about that. Luckily i had a voltage chart supplied by The Oracle that I could use to see if the voltages i had in the amp where correct, so starting with the power amp and moving my way through that and checking the preamp valve voltages I found that for some reason all the voltages on V5 were wrong. Traced that through to two of the leads having been swapped, so proceeded to put them in the right place.

Turned it on again, now had some signal coming through the OD channel, but nothing through crunch/clean, and also a weird oscillation sound when turning up the master volumes. Oh, and I'd somehow swapped them around as well. Another thing to fix.

Anyway, so first up the oscillation, which turned out isa symptom of the output transformers being connected the wrong way round. Luckily this is an easy fix as you can just swap around the signals that go to the grids of each pair. Would have been nice to have it wired all like the diagram, but wasn't to be, besides, it's just one pair of crossed wires, and a clean fix too.

Next up figuring out what was wrong with the channels and switching. For this went round measuring the optocoupler voltages on each setting to find the funny thing that 2 of them just read weird voltages when engaged. This caused a hell of a lot of head scratching until i found a little strand of solder jumping from the track it was on onto another creating a short. Cleaned and resoldered and sorted. Voltages all correct, but still no sound from the clean and but a faint one from the OD channel.

*sigh* not going well this, and it's this stage with multiple problems that is frustrating and time consuming and not fun.

Following that I was advised to check all my shielded cable runs, so I did, and then found the way I'd wired the FX loop was incorrect, as the amp layout schematic was wrong, so following a rewire I was kind of hoping that'd be my problem. However, this turned out not to be the case. I check all the shielded cables, checked for continuity, checked to make sure it wasn't grounding to the shield, over and over again.

Anyway, so now I have a faint OD (as in really really really faint) still and no second channel. Not good and pretty frustrating.

So, next step, trace through everything from the beginning. I started with the switches and input, making sure the input was isolated, all good, then got hold of a picture of how the bright/clean/od switch configuration should be wired.

Another mistake.

So, one rewire later (which has now made it look messier which is crap, but i should have done it right first time) and i now can can a very very faint clean and still have bugger all volume. Frustrating again.

So, I jumped the FX loop and it all sprang to life, victory I though, I rewired the shielded cables to the preamp board, did a quick test, and all good, volume at long last, brilliant! With that I screwed down the board, and prepared to go get some glorious tones!

Only to be greeted by false dawn version 2.0. I'm now also 3 days into trying to get it all to work, having sacrificed all my spare evenings, going to sleep trying to figure out what to try next. So this isn't good.

So, time to remove the preamp PCB again and start checking the rear/front for problems.

And lo and behold, it all works again. Annoying as hell.

So I then by mistake discover that prodding the PCB and moving it a tad with my plastic stick towards where it needs to be mounted cuts out the sound. So something somewhere isn't right... Frustration at maximum with not knowing what the hell is wrong, another night of sleep and wondering. To cap it all I've just found out the mid control pot is broken as well, so will need a replacement for that. All in all it's just adding to my annoyance and sense of some kind of impeding failure.

Anyway, next day, I have replacement pot incoming, and it's time to figure out what's wrong. So on advice i mount the board loosely, no sound, and then start pulling at wires gently with a bit of wood (chopstick is ideal or anything as long as you're not near the high voltages) and I finally find the culprit, one bad wire near the input that when it is stretched cuts out. I replace said wire and there I am, victory oh sweet victory!

On the one hand supremely frustrating, on the other I did learn a lot by having it not work first time, a hell of a lot in fact, so it's been kind o a double edged sword. Just need to replace that mid pot now, and that's the last of the issues.

In summary, this stage is properly frustrating and involved a hell of a lot of patience and asking for advice from Th Oracle, amp forums and going of intuition and just trying things out. The worst part is not knowing how long it'll take, the best, finally being finished! The advice I got to just keep at it and eventually you'll find the issue rings true, and as long as you kind of know what bits are what you can just slowly work your way through it.

Anyway, I'll leave you with the video I recorded at that point, a sort of semi victory, but one none the less! I've also found this amp has way more gain than I expected it to as well, so am pleased already, just need to fix that one last thing!

Interlude: Tube manufacturing process

If you're like me, I've always wondered how a tube is made, and came across this video and found it interesting enough to post, pretty involved making these little buggers!

Enjoy! (And ignore some of the simplistic guff spoken over it like "top secret coatings" and how it "increases the voltage" as by know you should know that a tube is a voltage controlled current device, right? And that any voltage amplification comes from the resistor above or below it and the varying voltage across that caused by changes in current flow)

Sewing it all together: Wirings, nest stage and a prerequisite of concentration

So, last I posted I'd done all the heater wiring and put in the transformers. A lot has happened since then, and I've got a fair bit of catching up to do with regards to posts about it all...

Anyway...

So, armed with a chassis now populated with transformers, heaters wired up, jacks in place the next stage is mounting all the rest of the things, input jack and pots, and running the ground bus wire through the ones that need it, and not through the ones that don't (on some of the pins). The casings themselves will be grounded via the chassis, which is why all that effort was spent with a dremel stripping the powder coating from the chassis many moons ago. This bit s pretty quick, just making sure you don't put the pot in the wrong place, and that you make sure the isolation washers are used on the input jack, FX send/return and if you haven't already, the output speaker jacks. The slave out and footswitch don't need them, so safe there. I also didn't bother with putting heatshrink over the exposed ground bus wire across the pots, as it really is pretty unnecessary there.

At this point it's also a fairly good idea to wire the mini toggle switches, and i found a good way to do this for the two swtiches connected to each other was to reverse mount them so they stick out the chassis which then allows you to wire them and maintain the distance they naturally have without needing to fiddle about in the chassis. So I did that, and wired them with all the "extras" sticking of ready to be joined to ground wires and pots et all, then reversed it back into the chassis and bent all the bits in place so they'd fit.

Right, that done, time to quickly wire any caps and components that sit across the pots themselves, which is pretty quickly achieved as well.

Next up, channel select wiring, this runs from a mini switch on the front panel to the footswitch jack and then to the board. For this I decided to do twisted wiring for neatness, and picked a different colour combination to the heater wires as to easily see what is what. I also did another twisted wire pair for the bas control in, again, different colour combination of wires. Colours are good, helps you see where the hell things are going and coming from. Imagine I'd wired it all up with the same colour, it'd be like staring into the gates of hell wondering whether it's a ground or live or signal wire... admittedly, if i did this again I'd also colour code the wires to preamp valves as well, with one for

fixed voltage connections and rails, the other for sinal/output etc, just so it makes more sense to look at. Again, hindsight.

Now comes the wiring all the bits together, starting with the power board. Ok, simple enough, figure out all the connections to the power board, twist the wires leading to it that are of any same colour together and attach them. This is actually pretty easy, with the only slightly confusing part the whole standy/HT fuse/where do we go now phase which is over pretty sharpish and wiring the board up is fairly simple. Then add the wires leading off the board. At this stage there's plenty of wire left from the transformers after cutting the wires to length to reuse for the power connections to the preamp PCB and such, so that's cool. Also a good idea at this point was to wire in some leads to the star ground for use, as once everything is in, this area gets a little bit crowded. I also ended up grounding the power and standby switch casings out of paranoia to the star ground even though this technically isn't necessary as they should be grounded via the chassis.

So I did that, and wired all the controls together and wired on the leads which will lead to the preamp board. All good so far, but starting to get chaotic, so cable ties to tie wires together in groupings is a fairly decent idea keeping them out of the way until you're ready to attach them to where they need to go.

Now, the next bit is kind of fun, and can be done when the heaters are wred to the transformer and initial hookup of power board is done. Basically, turn the thing on so you can see the power light come on. I found it a nice thing to do, just to reaffirm that everything so far is wired correctly, at leas insofar as heaters go. It's cool to see the pilot light come on for the first time as well. I also sneakily popped a few valves in just to see them glow, then took them out again, but it was cool to see!

Right, moving on and now it's time to attach wires to all the preamp tube pins. I did it this way and left a lot of wire so as to then attach to the preamp board. In honesty, and hindsight I would actually connect all the wires that attach to the preamp board to the preamp board next time, and then solder to the valve pins and front panel controls. Call this a learning process if you will, but it would have probably avoided a few errors which I'll be blogging about later. With all the wires attached it does look a bit like a birds nest and at this stage it's advisable to really tie things together that belong together for the sake of sanity.

Also this point is a very good point to wire up the input to the first preamp tube, and also any other shielded wires that go to the front panel controls. I also wired up the shielded cable destined for the preamp board. However, this s a mistake insofar that it becomes harder to work with. Wire it to the preamp board, and cut to length based on placing the board in place and leaving a bit of play and allowing for the connecting to be straight onto the pin as we want it at 90 degrees to the chassis so it doesn't go near the heater wires. Again, this is from experience debugging the amp and needing to fix things later on...

So, what we're now left with is a bird's nest of wires and we now need to add in the preamp board and just start attaching wires as we go...

First stage is leave all the power amp/ power from power PCB etc etc well alone as they'll be easy to do once the front is done, and we want to keep signal wires as short as possible on the preamp. Not too short, but with just enough play in them not to have stupid stuff happen later down the line (again, this is hindsight, with so much of it I'd not be surprised if it being 20/20 by now is an understatement and that it's actually giving superman a run for his money)

So, take the wiring diagram, and slowly, from V1->V5 (right to left) start wiring it all up one wire at a time. Measure length, strip, feed into preamp bard, solder. This took longer than i though as well, that with it being incredibly fiddly to attach the shielded wire from FX send and V2/3 gain stages etc at this point. The inner core is fragile, hence best soldered to the preampboard first and THEN  soldered to things like valve pins.

At this point I'd also like to add that the shielded wire i got has been and still is an utter pain to work with. It's stiff, not very flexible, and wire strippers do not work on it, and so I've been using an exacto knife to cut it to length, expose the shield, and expose the core. Tedious long winded process that is still so. I'd get more flexible stuff in the future to be honest, preferably with a thicker signal wire in it tat is less flimsy and prone to snapping. Another tip I should have listened to from the beginning was to not use the shield as a connection, but rather solder a bit of bus wire round it, and ten use that to solder to wherever the shield goes. Trust me, doing it the way that seems more complicated and perfectionist actually saves you time and a lot of hassle later on by a significant margin.

Right, anyway, once you've wired up the front panel stuff and tubes, then just attach the power wires from the second 6.3vac supply to the switching circuit, again, twisting for neatness, attach the signals to the power valves ad then ground wire to the ground star and a few other wires from the power supply. Attach the bias pot to where I didn't solder on the trim pot (used a pot that can be adjusted without removing the amp from it's chassis) and finally hook up the send wire to the FX loop.


And then, voila, fully wired amp. Now all that's left is to see if it'll actually switch on fully. The next bog post will be about actually turning it on with full HT voltages across the valves, biasing it and actually seeing if the whole thing works

I have to admit this was also the stage where I started wondering "what if I've just built an expensive mess that doesn't produce sound" etc, and anxiety starts to creep in as well as excitement and hope. You just want it to switch on, plug a guitar in, and then celebrate glory with a massive shit eating grin. I'll come to that story and how that panned out next time, but for now all wiring is done, attached and everything is in place for the moment of truth...

Heaters, power and wiring the basics up and the magic of a step drill

Power transformer through holes with  grommets

So, last post I ended with a tinge of frustration seeing as i couldn't finish the last of the drilling holes. The holes for transformer wires i couldn't get big enough, and didn't have the right sized grommet.

Power transformer feedthrough

Frustrating indeed. SO on advice I ordered a step drill bit, a drill bit with many levels used to drill nice round holes. And boy do I wish I'd got this earlier. It would have made everything so much easier. For the m3/4/5 screw holes I'd still use a drill bit though, but anything larger and this is the answer. Perfect nice round holes with minimum effort. I wanted to find more stuff to drill through, but figured I shouldn't get carried away lest everything I own ended up looking like cartoon swiss cheese...

Anyway, I drilled two nice 14mm holes, and added freshly delivered grommets to them with minimum effort, result looks cool and will stop the wires getting chafed and thus electrifying the chassis, which is not something that is in the best interests of my health and longevity to happen...

Checking everything fits through the holes

Anyway, a quick check to see if everything fits nicely and after confirming that, a quick bit of cosmetics adding grommets to the unused holes in the bell ends either side of the transformers. This has no bearing on the sound (no, the tone won't leak out before you crack that joke) but it's nice, and will satisfy a sense of inner pride.

sans grommet

with grommets

That done, time to do heater wiring, I'll mount the transformers later, but for now I want the chassis to still be at a level where it is easier to work on, ie, desk level.

Right then, heater wiring. For this on both sets of tubes on this amp the heaters are wired in parallel. A lot of the other wiring I'd looked at used twisted heater wires (to cancel out noise in each other and to help the amp remain a bit more noise free). But on the slo they are parallel which should achiever much the same effect. Plus it looks cool. Anyway, to achieve this I used bus wire, feeding it through the pin, then adding some clear heat shrink cut to the length of the distance to the next pin (suitably rated for high temperature, you do not want this stuff to melt). For the power valves this involves twisting pins 2 and 7 so there's a clear line across all the valves, and feeding one wire through all of pins 2, and through all of pin 7. For the preamp valves, same deal, except through pin 9 and twist 4+5 so they allow a clear run through them (as pins 4 and 5 are attached to the same heater run).

Next, hooking the two pairs up. For this, I did need twisted wire, and found the best way to achieve it was to put two wires into a drill instead of the drill bit, then hold the other end with a pair of pliers and give it a quick (very quick) spin. Took a few attempts of not being quick enough and it slipping from the pliers forming effectively a strimmer beating the crap out of me like a madman with a whip. You learn pretty quick...

So armed with twisted wire, i hooked up the two heaters and also the bus wire to the tag strip. First bit done. Next, connect the individual pairs of tubes up, and wire the bias points. Pretty simple and not too bad. Then add a ground bus wire, and hook that up to the speaker jack sleeves, I'll be adding the "0" tap from the Output transformer to this as well later. Also, same tactic as before, bend the socket pins so they form a nice straight line out of the way of the other nice straight lines.


Next up, and the elevated heater mod, which is a cap+resistor in parallel to ground which is then attached to the center tap of the heater supply, or to the faux center tap if you don't get one from the transformer. This is not essential, it's a nice to have, but is another way of minimizing noise from the heaters leaking to the cathode (seeing as it's 50hz/60Hz hum you'll be getting if things are bad. This is also the reason for twisting your heater wires).

That done, time to mount the trasformers, no getting away from it anymore, the rest of the amp will be built with them on. A lot of "difficult" time later (they take a while to mount) and with wires fed through, I can now solder the 4,8 and 16 ohm taps to the selector switch, all good. At this point I muust mention that the negative feedback (which goes to the preamp/deptyh mod if you have one) should be soldered to the 4ohm tap, and the slaver output is soldered to the 8ohm tap. Forget these and all that nice neat heatshrink will be for nothing (like ibn my case) so it's wise to solder some nice long bits of wire to them at the same time. A

Anyway, once the impedance selector is hooked up, the output soldered to the speaker jacks (starting to feel more real now) it's time to hook up the anode wires.

Now, hopefully I've hooked them up the right way round, one wire goes to the left set, the other to the right set of power valves, get them the wrong way round and you allegedly get massive squealing. It'll also mean messing up the nice wiring... anyway, same deal, run into the correct pin, then make it run parallell.

At this stage the B+ wire (high voltage supply) can now also be run across them and with that all the parallel lines reach saturation point. Looks nice though. And is satisfying too.

Add the brick sized resistors between the high tension supply and the anodes, and then solder it all up (the B+ wire).

Following that, it's time to connect up the heaters to the power transformer heater ouput, and finally the pilot light...

Them wire in the on/off and standby switches (as much as can be done without the power board) to complete this rather long section...

 

So now the transformers are all mounted up, next step will be to wire up the power board, followed by the preamp board, but that's for another post.

Chassis drilling and layout and transformer mounting - Don't put the cart before the horse

So I spent last night lugging home some rather hefty transformers from inMADout all excited thinking I would just drill the mounting holes, drill a hole each for the wires to go into the chassis and do a load of work on the amp. Exciting!

However, this is not how it panned out.

Anyway, we'll start with the good stuff. Firstly the inMADout transformers are cool as hell looking, I got them with matte black covers and they look mean! There are also a hell of a lot of wires poking out the power one, and a fair amount out of the output one. They also have all the wires out of one side, which I've been told is the "vintage" way of doing things. Anyway, I reckoned less holes, right?

Next I decided to revisit the tactic of making cardboard templates for the transformers so I could place them where I want to drill and be able to line them up nicely. All good as well, just grab a piece of cardboard, trace around the transformer, colour in the holes so you know where to drill, and then to get your blue peter badge, cut around the outline ad bingo, one template.

The first consideration when figuring out placement was whether the bolts from the power transformer would not get in the way of the capacitors on both sdes of the power board. Now as you may remember, this board is a tight fit, and there is no room where the capacitors are so the bolts needed to avoid them. Next consideration was to leave at least 20mm space from each edge so that when it goes into the headshell it'll slide past any brackets on it used for mounting grills.

All good so far.

pcb mount screw hidden under transformer - countersunk

So, I start drilling, get the holes for the transformers done pretty quickly and cleanly. Then decide to go and countersink the holes for the PCB mounts and earth and tag boards, as screws sticking out just does not look as good. All went well apart from I broke my HSS M3 drill bit by attaching the countersink sleeve bit to the twisty drilly bit of the shaft rather than the shafty bit of the shaft (yes yes, technical terms and all that, i know, lacking). Anyway, all cool, and good thing I did, as one of the PCB standoff mounts is right inder the output transformer so needed to be countersunk. Also I got away with all the holes for M4 screws just about. I wouldn't have been able to contersink anything larger (M5 and above)

The I decided to look at the choke. Now this is mounted between the power and preamp PCBs on the inside of the chassis. So first thing to check was placement, and I am happy I did. So i lightly attached the preamp board with 2-3 screws, and just slotted the power board on, and then went to position the choke. Very very tight fit. And a lesson learned almost badly. I was lucky there was just enough space with it almost flush against the power board leaving a decent enough gap between it and the preamp board (I hope). Still, if I had moved the boards by about 20mm closer together it would not have fit at all and I'd have had to drill a load of new holes in the chassis to move the boards.

So here is the first lesson:
- No matter how exciting it is, do not do chassis prep until you have the transformers, choke, and ALL components to be mounted on or under it.

Anyway, a lucky escape.

So, next I though I'd just drill holes for the wires to fit through. I had some grommets, and I reckon the wires would fit through them. So I drilled my pilot holes, all good, then drilled larger holes, all good, tried the grommet, larger hole required, so out come larger and larger drill bits until I hit the 10. Ugly ugly process, and I would not advise using a normal drill bit for anything above M5/M6 holes, probably 5...

Right, holes drilled, grommets in, transformers positioned on chassis, start poking the wires through the grommets. Simple right? Wrong. First thing, the holes and grommets were too small. I could ust about get 6 wires through, maybe 7, but then getting them through pulled he grommet through. So, grommet and hole too small. Frustration. So at this point I stopped realizing that I was just going to get really annoyed really quickly.

So, I needed a plan. First plan was to use the countersink bits I had, which are large enough, to slowly drill it out both sides, but luckily a friend pointed out the existence of a step drill bit, which after watching a quick video tutorial pretty much seems like one of the most useful things on the planet, and something that can be used to punch tube socket holes if I ever get a blank chassis (although seeing how I am hating working on the chassis (more likely because this is the first time) I may not go that far).

So here come the next lessons:
- Drilling with mounted components vibrates all the screws nuts and bolts loose. Do all the drilling before you put stuff in the chassis.
- Get the right tools for the job.
- Go and youtube how to do stuff instead of figuring you already know how to. Or ask someone.
- Be patient. very patient. No matter how much you want to do something, it's not worth the anger and frustration because you rushed and did things out of order...

So, basically I am now waiting for larger grommets to turn up and a step drill bit and a deburring tool. As I don't like slicing myself open on the sharp edges of holes I've drilled, and the dremel does not work well on getting rid of them, at least not the one I have.

Amp chassis with transformers loosely mounted

And in conclusion: Chassis work is a pain in the arse, certainly for a first time build and I'd recommend getting one prepunched if it's the first time doing this as you can spend more time on the fun stuff. However, if you can't, then at least make sure you have the following before you start:

- HSS drill bits from M3-M4
- Step drill bit (that can do metal sheeting)
- Countersink bits or attachments you can put on drill bits
- Dremel, get the real thing, and get the right angle converter, it'll make getting rid of coating where you need to much easier, and less dangerous than the way I did it. Just spend the money.
- Deburring tool so you don't go all Emo and cut yourself all the time
- Templates of all the tings you need to drill
- Tape to tape the templates down
- Some kind of device to measure right angles so you can line everything up easily
- A good plan

Anyway, after what seemed like a bit of a failed evening with excitement turning into frustration, I decided a bit of zen like painting was required and proceeded to paint all the screws that will be visible on the top the chassis black. Matte black. To match the transformers. A god way to end the evening and feel like I'd at least done something right.

Bit of a tight squeeze with the choke!

Then I did a quick test mount of transformers, power and preamp PCBs and choke to make sure nothing is in the way of anything else. All worked out well enough, so at least it didn't turn into a disaster!

Anyway, I'll have to finish all the drilling before I hookup all the heater wires and power wires to the tubes as drilling loosens screws, so another delay kind of, but I think part of this life experience is to learn patience and order like some kind of zen like lesson for which I am sure I do not possess the correct outfit/uniform...

Soldering the Preamp board

I said i was going to write up a bit more on this, and as I've already let the monkey fall from the sleeve (love that saying, my old economics teacher's literal translation of a dutch proverb, when he meant letting the cat out of the bag) there might be a slight lack of pictures. Mainly as I filmed the whole thing and forgot to take pictures.

Anyway...

So I was expecting the preamp board to be a bit more involved than the power, but really it's just a case of taking the printout of the scan i made of the board, and then firstly drawing on all the components as well as their numbers (ie R32,C43 etc) to denote whether resistor or capacitor. This took two attempts and a lot of head scratching (not due to nits I might add). First thing was wondering how the hell I'd ended up with a capacitor that seemingly didn't fit anywhere that seemed to be pretty integral to the operation of the depth control pot. Eventually with help from The Oracle (Tony, who's been helping me when I get stuck) it turned out that the PCB I had is for an original slo which didn't have a depth control.

Onto a bit of improvisation then, and the only place it seemed mountable was down the sde of the board, and it seemed a good idea to cable tie it. So I made a hole usng a screwdriver and a drill bit slowly drilling through the PCB by hand (it's not something you want a drill to break, slow and steady wins the race apparently, although I am sure this is a lie in any competetive sport). Anyway, that done I then spent the best part of at least an hour drawing on the components one by one and cross checking against the amp layout. Having a different PCB didn't help at this point, although it is close-ish to the amp layout I have. So a lot of time was spent figuring out where about 10% of the components should go and tracing tracks and double checking to make sure.

Wire bending tool

With the diagram done on a piece of paper I then went off and started soldering. This bit is pretty fun, and not really that hard. With a bit of care and due diligence and the amazing wire bending tool you end up with a nice clean result. Anyway the way I was advised by The Oracle to do this was to start with the smallest components by height, and then slowly build up. This means grab the things that when mounted will stick out the least and do them first, so when you flip the board to solder, they don't drop out. Anyway, as there are a few jumper wires on the board, I started with them (very important to mark them on your drawing, as they are easy to forget, and REALLY fiddly to do once there's a load of components on the board). Then I proceeded with the bridge rectifier (for the switching circuit). With this bit orientation is important, you want the AC (squiggly lines) orientated correctly so they are attached to the AC supply terminals. (That is unless you like things going bang and smoking lots. In which case there's a Youtube channel here that'll satisfy all your destructive desires: ElectroBOOM)

I then went and did all the resistors, moving from left to right for no particular reason other than probably that that's the way we get taught to read books in the western hemisphere. After which I sorted the capacitors into sizes from small to large and tackled them. At this point I should add, for the resistors it's a good idea to start at one end of the board and slowly move to the other side doing them in order of placement. Also, as you do each one, it's a good idea to tick it off on the drawing you have on the PCB so you know what you've done and can track anything missing. Capacitor wise it's a bit more chaotic as if you're doing it by size you'll be jumping all over the board, but hey, the end result clean board is worth it right?

With the capacitors one annoying thing was them being longer than the distance between the mounting holes on the PCB. So, one set of small pliers, I ended up bending the legs inward, fold over the edge, then outward again judging the required end distance between the pins by eye.You kind of want to end up with something like the image here which I've found as an example. It'll allow the cap to sit flush and the board to look clean, which is a good thing ad will satisfy your OCD when building. Also, clean electronics mean less of a headache later on when you invariably will need to troubleshoot something or much later down the line when you might need to replace a part (or add one when modding)

With all that done, just needed to add the depth capacitor to the side of the PCB and cable tie it into place resulting in the following wired PCB board (although it is missing the bias adjustment pot, the reason for this being that instead of being mounted internally it'll be mounted on the chassis as there's a nice convenient hole for it there meaning I won't have to pull the entire bloody chassis out to bias it like most amps require):


So there we have it, all the PCB wiring done. I'll still need to connect all the wires going from the PCB to the tube sockets and things like front and rear panel controls, FX loop etc, but the easy (ready non fiddly) bit of the wiring is done.

The next bit of wiring will be the heaters and lovely power valve and preamp valve socket stuff as that looks like a right time sink to do properly, but also like something that'll be pretty cool looking when done.

This is also a fun part to do. Seeing as there's loads of stuff that isn't fun, in future I'd probably leave this till after having done all the chassis work, transformer mounting and wiring of sockets as something of a pick me up. I'll know for next time.

Anyway, that's all for this post, the next one will most likely be on the hell of mounting transformers as that has not been fun ad is still ongoing..

















 

Soldering Time lapse video!

Quick post this, and I have a lot of catching up to do. Basically I soldered the preamp PCB before the weekend, and got through it with only one mistake of swapping 2 resistors round which was easily sorted (and luckily i caught it in time). The labeling of components in bags definitely helped a lot. My PCB having a slightly different layout to my blueprint cause some problems though, but managed to work round them. Anyway, here's a fun little video to watch of the whole process. I'll write up on the ups/downs another time, and there's a section on transformers and mounting hell to come (including drill bits not large enough to create a hole all of the bloody wires will fit through)

Soldering the power board

I decided to tackle the power board first, mainly as it has less components, and also to test out the new soldering iron. All in all pretty good going.

Best cool little tool for OCD ever

I used the wire bending tool to nicely bend the legs on the diodes and most of the resistors, apart from 2, where the board was obviously designed for larger fatter ones, so I kind of had to just have them with long legs. Not the nicest aesthetically, but it just needs to work at the end of the day, and it's not like you'll be able to see it once the amp is in it's headshell anyway, even if I do want everything to look neat tidy and pretty as a matter of personal pride.

Printout with components drawn on

Anyway, so I started off with the printout of the mirror image of the PCB, this to be able to draw the components on first, along with the component names, this way (seeing as the board I have is unmarked) I could refer to it whilst wiring, and also so I could grab the bags of components I previously labelled (in one of the previously described mind numbingly boring steps of preparation) and solder them on.

Going from Tony's advice I started with the shortest components first, ie the ones that will have the least height when soldered on. This makes it easier to solder on the reverse and to stop bits falling out as they're resting against the table. Makes life easier. From there moved onto the diodes, then the smaller caps and finally the 6 large ones, of which 3 needed to be mounted on the reverse side of the board.

As the PCB is meant for longer axial capacitors I was left with the dilemma of "long bit of bare wire" that I didn't like, so I cut heat shrink tubing to cover each leg to length, and then mounted the top ones. The soldered. Finally I mounted the three at the bottom.

Now as the three at the bottom were running across tracks, I was a bit paranoid after doing them, so decided to see if some cable ties would fit under them, to stop them making any contact with the tracks on that side of the board. Happily they did, and so 4 cable ties later (1 wasn't long enough to go round them all, so had to elongate by using a second, and I wanted 2 for symmetry, hence 4) problem solved (even though it is being overly cautious). Then, for looks and completionism (and probably OCD) I went and did the ones on the reverse side of the board.

Spot the glaring mistake...

Next, I went to do a test mount of the board. At which point I noticed the standoffs (20mm) meant for the power board were not going to work. Also the 40mm ones of which I had spare, they were too tall. All this because of the caps mounted on both sides. Disaster!

Then i remembered the bag of parts I'd ordered on a whim from ampbuilder which had some small (i guess 10mm) standoffs that I thought were useless. These combined with the 20mm ones actually turned out to be exactly the right height, and test fitting the board left enough clearance on both sides.Result! And also a victory for hoarding and not deciding to throw the "useless" stuff away. Not that that's a good thing reinforcing my hoarding instinct...

Reverse of the board

Mistake rectified

And then, then I looked at the board and though"that looks a bit bare and empty" and suddenly realised I'd completely forgotten to put one of the caps on. I can only imagine the embarrassment of going "why doesn't it work" later down the line, to discover something that stupid at fault.

Anyway, removed the board, put the missing capacitor on (pretty big one to miss as well...) and all was well with the world.

All in all, pretty pleased with the result. I've also come across a nice picture of an elevated heater mod, but more on that when i get down to doing the what seems painstaking work of wiring up the heaters and other fun rails across the tube sockets...

Oh yeah, also videod it, but I'll probably do the next time lapse video in with that of the preamp board, which is the enxt mission as I am not going to do any chassis wiring until I've got the transformers.

All coming along nicely! I can see this being addictive...

Finished article in the chassis

More Chassis work, drilling and mounting little bits here and there

Today has been spent getting metal drill bits from Screwfix (so exciting, first time there, I was beside myself with euphoria) and then finishing off the drilling and some of the sanding, attaching the star ground, the mount for the faux centre tap, IEC plugs, fuse holders and a few other bits including the sockets.

Not terribly exciting, and I'll priobably need to remove some of the parts to do some wiring (like the fuse holders and bias points) but I just wanted to see it look more like an amp.

Also added the preamp shields, which are a kind of black but more dark grey (can always paint them later) but it's looking cool so far

I guess I'll start soldering the boards next, and eventually when I get the transformers do the drilling to mount them as well, but that can wait.

I tried countersinking the holes for the PCB mounts, and it didn't go entirely to plan, so I'll need a better attachment for the dremel for that (and countersunk screw heads) but it's not terribly pressing. I am learning as I go along, and also I need some paint anyway as I accidentally removed the paint for the input jack which was one of the holes I shouldn't have done. Live and learn, no big deal, and it's just the inside that'll get painted, so once i get some white model paint that'll all be OK as well.

So I guess next up is either the soldering of the boards, or if the transformers get here mounting those, drilling holes to put the grommet in for the wires and attaching a bunch of stuff on the chassis, in which case I'll do the heater wires, B+ supply, faux tap and all the fun resistors across that power valve sockets as well as adding wires to the preamp tube sockets and marking them read to be attached to the boards.

So one of the two things, but both will involve cracking out the new soldering iron I treated myself to, which will hopefully be better than the one I have been using that's sort of falling apart.


I also did a neat little time lapse video of the whole thing, using the gopro on a mount and edited it with all the work done so far. It's come out kind of fun, so I'll definitely keep doing this as it's fun to see it happen! I also wish I could move that fast, but alas I can't... Anyway, enjoy:

Sanding down Chassis (or how to make cool sparks with a rotary power tool)

Believe it or not, I actually got something done that isn't sorting parts into bags and boxes! And it involved playing with a power tool I've never used before! Double win! All whilst under the influence of Lemsip/Beechams/Whatever trying to keep a cold I've picked up at bay. Power tools and muddled mind not always the best combination, but on the other hand you kind of lose sense of levels of what is allegedly safe and definitely experience a dip in caution, so it balances out in the end, with the man flu induced haze and lack of thought balancing nicely against being oblivious...

So, what did I do? I started sanding all the chassis parts that need the paint taking off. Why? Well, so that a lot of things like pots, input jacks and other things that people will be touching or going near will be grounded to the chassis, which will be grounded to the mains. For this I had to remove the paint and get down to bare metal behind the power, standy switches, the input jack, all the front panel EQ and switches and controls as well as the impedancve selector out back and the slave out and level.

However, the bias point, speaker outs and FX loop were not to be done. So basically, i went off and taped up all the holes not to be done, as well as around the holes that were to be done., ending up with the chassis looking like this:

Now, I also have a bit of a test before, making sure jacks fit in jack sockets, and pots fit in the places they were supposed to (just in case the holes were too small) etc. The only thing that didn't fit was the pilot light (all important blinky light) so I marked that as something to do and to widen whilst I was at it.

I also went ahead and marked where i needed to drill holes for the IEC plug earth, the star eart mount and a hole to mount the tag board for the faux centre tap (whuich finally made sense in my head as being like a transformer center tap, no idea why it took so long to register).

i also taped down the cardboard copies of the PCBs I made earlier, and lined them up so that they had enough space after having considered the placement of things like tube sockets, fuse holders, pilot lights, switches etc. The preamp board wasn't a problem really, but the power board is going to be a tight fit next to all the sockets and other big bulky stuff that will be mounted in that area.

This all done, I rigged up the go pro, and started filming, for posterity. It'll probably induce face palm moments and WTF exclamations from people that actually know what they're doing, but as I had no clue which attachments to use, well, I just kind of experimented as I went along.

I picked small sanding attachments to do the inside edges of all the holes, which went well (with the odd cool spark shower which is entertaining, although apparently I am "a foolish human being" for not wearing things called safety goggles, which I don't have either, but hey...). I then moved onto the sanding part, putting the rotary drill through each hole, then attaching a sanding disc, and pulling back through the hole to sand down a circle on the inside of the chassis. First few attempts i didn't quite attach the sanding circles properly, so they ended up flying off a few times, but I got the hang of it after that. It also means I should never ever train anyone on Health and Safety (ie, how not to do anything fun ever again). I lumbered through, and got all the bits done I needed to as a first pass.

The end result? Almost there, whilst it is easy to get rid of the paint inside the holes (the edges), actually getting a nice cleared circle behind each part is trickier, and I'll need to have more of a look at it tomorrow and see if I can have a brainwave of using a different attachment to make it better, but on the whole, it's ok so far:

As you can see needs more of the paint gone, although whilst it might be "ok" I do want to do it properly.

One thing is that it was a pain in the arse to do. I had to put the dremel through each hole, then attach a sanding disc, turn it on, and pull back on it hoping it'd get rid of the paint, not ideal by any means, but no other choice as the rotary tool was too long to fit in the chassis. I'd actually probably end up buying a real dremel if i were to do this again, and get the right angle attachment they make for it. It'd have been faster, a lot safer and I'd have more control over what I was doing as well. But, I'll soldier on with the cheap one I've got (I actually do love this tool, so so so much fun, I must stop myself from thinking of things than need holes made in them, but also means it might be worth getting a proper one of them, but I'll see)

After all the sanding, I attempted to drill the holes for the ground, but kind of discovered that in the battle of drill bit vs steel chassis that the drill bit lost. badly. The first one kind of ended up 1/3rd shorter than when i started, with it barely making a dent in the chassis. The second drill bit seemed to be making headway until it started glowing bright red like the depths of a volcano at which point it seemed prudent to stop. The chassis? No hole, just a slight indentation one side, and a raised point the other. I'm guessing I'll need a proper drill for the holes (which I have, but can't find the chuck to put an appropriate sized drill bit in it) and actual drill bits to go through metal.

So, that'll be the next job, finding a way to drill holes, and probably also countersinking the ones for the PCBs to make it look nicer overall, but first I'll need to find drill bits that don't end up losing against the might of the chassis...

As for the video, I am thinking once I have more footage I'll get all the videos and time lapse them together going from one bit to another to keep it interesting and show the whole amp from start to end.