Just a quick one, but whilst watching the second video in the series (see below), towards the end there's a nice little nugget, that being a designer tool for power supplies. Awesome! Anyway, the goodness can be found here on Duncan's Amp Pages, and looks pretty nifty! Probably worth looking at if you want to design a PSU (or for referencing for myself for later use)
These videos if you mine them for little tidbits are proving really informative, so I am definitely sticking with them and recommending them.
And here's the PSU video, which is a pretty good run through of how everything looks (as well as some nice stuff on screen resistor taps for linearity)
As a side note, looking at my output inMadOut output transformer, it has no screen
grid tap, but going off the analysis being done in the videos of a
fender amp, that does use one, so this is interesting. Something to make a mental note of. Another nice thing is pretty much having a "oooooooooooh" moment of the whole triode operation switches on the back of amps is pretty much a switch that just connects the screen grids (1 or 2 depending on if tetrode or pentode) to the plate. Seems like a simple mod to add later that just involves a simple switch...
So, not much progress at the moment, other than i managed to order some parts (valve sockets, shields, IEC plugs, light, jewel covers to make power light pretty and other gubbins) so I'm not really going to go into that, other than that I have forgotten how to count, and for some reason thought the BE100 used 5 preamp tubes, when it actually only uses 4. So that was dumb, and as a result I'll have a 5th of all those parts. On the bright side, there's a margin for error, like, for instance, if the toolshed elves decide to steal 20% of my preamp parts, I'll have that covered...
This isn't about that, it's more about me having a slight panic. The reason for this is pretty much eh following. On my last (and first) build, there was a ton of docs out there. Boards well defined, loads of layout info, you name it, all there, so it was pretty much paint by numbers once I'd drawn the parts on the printouts of the PCBs.
This time however, less lucky. What I have are some layouts on a rev1 board, some boms, pics of an real BE100 inside, and some variant layouts (to build a JJ, maybe a phil X etc, basically, not sure, as just want to build the BE100 to start with). This would be all good and well, until I today decided to take one of the boards I have, and start soaking in the layout byu looking at what I had and the physical board.
The game of spot the difference (fun when you're a kid, keeps you quiet for ages) quickly turned into "try to spot the similarity" which is less fun when you're looking at a board that say "rev2". Quite a bit is moved, the board have no R or C labels (like r1, r2, r3, c1, c2..c30 etc) which then means either I:
a) time consumingly measure each connection on the board and see where it goes and draw out the board, then compare that to the circuit diagrams, and slowly build it up from that.
b) try to look at the low res .png file of the rev2 board i found buried in the docs, and try and guess what some of the resistor and capacitor names are, as they are usefully in light grey on a white background, and even more usefully sometimes obscured and completely illegable by some kind of whatever.
c) buy another board set
or
d) panic...
The problems are:
a) I'll lose patience, and walk (head down, despondent) down the end of the road to have a conversation about the meaning of life with the goat and donkey who get tortured by visiting kids daily and have obviously accepted their sad lot and given up on the proposed topic of conversation(the donkey makes eeyore (or whatever his name is) look like an optimist). This path means this blog ends for another year whilst I end up doing things that are decisively less time consuming and dull (and frustrating)
b) Just means the above, but in a different form. My eyesight isn't good enough, and more importantly the png isn't high enough res by far, so the labels pixelate before you can get any clues out of them.
c) Too stubborn. Not going to happen. I will prevail, if not today, then hopefully this decade.
d) Well, kind of went there.
Anyway, so I spoke to the oracle (Tony). Decided to follow his advice of contacting the guy that made the boards, see if he has updated docs. Success, apparently tomorrow I should find something better. Even a translation from v1.0->2.0 of the board will do. I can then do some drawing by numbers.
So, in light of all of this, I kind of realized I had not understood the slo circuit when i built the amp and had just been soldering by numbers. I had meant to, but just didn't. And that kind of annoyed me a bit, as it was meant to be a learning experience as well.
What to do? Time to rectify the situation, and bridge the knowledge gap (see what I did there?)
So today I have been refreshing some electronics knowledge, having a look at simple tube based gain stage circuits and just ramming home what each little bit, resistor and cap kind of does on a simple level. Kind of let it soak in. The aim is that after a few days I can look at the BE100 schematic and know what each bit does, be able to break up the stages, understand the tone stack and in general see what I am building, and then hopefully percolate that so I can then know what mods do when I hopefully add some.
So yeah, that's the plan really, just dust off my degree from 21 years ago, become less rusty and start thinking in electronics for a while.
Anyway, point is, I stumbled across the video below, and it really just gave me a "oh, that's cool, I get it" moment I'd been missing. I am working my way through the series and find it well explained. I've also been treating it a bit like a lecture, and been taking notes. I'm currently watch the PSU one. Tomorrow ("it's only a day away" - as sung by the ever optimistic orphan annie) I'll do the push pull section as a refresher, and work my way through them.
So, here's the video, worth a watch if you want a very simple run through of the various bits of a diagram as a start (wasn't my issue) and want a quick primer on a bunch of useful stuff and on the basics of pin out connections, what the load and bias resistors are, coupling caps, some quick other bits and where they live on a diagram. Sometimes it's better to see and hear rather than read.
Anyway, I reckon once I really get my head around the BE100, then the slo circuit gets revisited. Should stop me looking like a bit of a simpleton in front of The Oracle as well. Which would be nice. As asking tons of stupid questions just isn't good for one's ego...
So yeah, I've been waiting for some stuff from Russia to arrive, and haven't wanted to miss the doorbell, as otherwise the evil postman from BPost takes my long awaited package, and then deposits it at the local Spar (read: slightly larger than corner shop (and not on a corner) of disappointment that is never open at any hours to make it useful). The problem with this is that I still don't have a local ID card (blame bureaucracy and software issues) and have just sent off my passport for renewal in ze motherland, (which I might get back in 2-4 weeks? I don't know...). Unfortunately (and rather annoyingly, going int passive aggressive rage inducing) the guy there doesn't seem to think a drivers license, which has a photo, of my head no less, and my name (amazing) is sufficient.
This Russian cargo, I might add, is exciting, and pertinent to this blog. Let me explain. After seeing how nice the chassis was for the current BE100 clone build, I had a look at his other stuff, and then "by accident" (I swear, it is always by accident, I have twitchy mousefinger) I order a JTM45 chassis, another slo chassis, and a slo headshell and some grills (my excuse here being I still have a spare slo100 board, and it could be fun to build another one). Couple with, well, I'd like to build a point to point wired amp at some point as well. And the JTM45, being back from the 60s, aka, golden age of tubes, aka, really really simple circuits, shouldn't be too hard to do (plus it'll generate some "oh look I can use a soldering iron, please marvel at my joints and carefully selected components" instagram posts).
All of this, you probably didn't need to know, and you've been wondering "what the hell ahs all that verbal diarrhoea got to do with the damn picture". So, back to the doorbell.
So the doorbell goes, and as I've been watching tracking like a hawk, i run downstairs thinking it is the above.
No such luck. Crappy Amazon parcel. Not very exciting. So I kind of gave up for the day, thinking, maybe tomorrow...
However, in my morning malaise (after feeding the chickens, henceforth referred to as the consumers of all things) walking back to the back of the house I noticed a box. On closer inspection, said box was heavy. I also had no idea of what was in it, or why it had Belgium misspelt as Belgio.
Suddenly, realisation, these are transformers! I'd literally forgotten I had ordered them from the rather excellent InMadOut. Only slight niggle is that he refused to paint them Donald Trump toilet seat gold (to match the chassis), but other than that, again, they look fantastic. Very pleased with them, even if they are still loose. They seem large and chunky which is nice as well.
Anyway, part of the BE100 build had a separate 14v transformer as a requirement. When I asked InMadOut about it, Magneto (forgotten real name, but as it's magnet related, the new name for him is apt) suggested he just added it as another tap on the mains transformer. So this has a 14V tap, which will be used for the relays I believe. Which is cool, as it'll be less clutter.
Choke looks quite chunky as well. As the BE100 chassis isn't as deep as the slo clone one from previous posts, I don't think I'll be able to mount it internally, but I figure as the amp will have solid front, and have air vents in top and rear, that I shouldn't really get too carried away by making things look pretty on the inside. Yes, contrary to popular belief, beauty is on the outside, not in.
The arrival of the tranformers also means that I now should really get the component order sorted out, as well as order tube sockets and various other bits and pieces from tube town.
On top of this, and I'd almost forgotten about it, a friend of mine sent me some extra infor on some choice mods he made to his BE100 build. I kind of like the idea of being able to switch between the 4 and 16ohm tap for the negative feedback loop. I also think that unless the BE100 already has it (haven't studied the schematic well enough) I'll add an elevated heater mod here as well.
In any case, amp build D Day is approaching, and I do plan to do some videos like last time, as they came out quite cool (well, I thought so anyway).
So, hopefully reading this inane drivel has kept you off the streets and out of trouble for a few minutes, and next time I might actually do an update that involves something other than "here's what I got in the mail"
You know when you do something really fun? And the end result is awesome? And then somehow you descend into other spheres of OCD madness? In my case this was a car obsession for a while, then I dabbled in pedals, but I've kind of realized that it has been 5 years since I built the last amp and that's a bit too long...
Not only that, but I think completely fucking up the power board of the 5150 trying to get it out (they REALLY don't want you to remove it on the first run, i mean, it is literally riveted on WTF) and then messing it up even more thinking I knew what I was doing but then melting the tracks off the board... well, that little experiment cost me a new board from peavey, so i just retolexed the bastard amp and put it back together with new power board.
Anyway, you don't want to hear about that, do you, you're not my unknown virtual agony aunt, who I tell of all my woes, you're not my virtual shoulder to weep crocodile tears on in a pathetic attempt to gain some insincere sympathy and all that crap... No, you're here to read my adventures and mishaps as I go for amp build #2!
So, what is this build then? Well, about 3 years ago or so I bought 3 PCB boards of a nice chap in a trenchcoat in a tube station back in misty London town, in something akin to a drug deal gone geek. After this encounter, and with what looked like (and still do) some very high quality PCBs from a limited run I was convinced I had the get up and go to go off and build. The amp in question? A clone of the Friedman BE100.
As I didn't have a Marshall style amp at the time, I figured, hey, why not. But then, well, you know, things go wrong, and you start making excuses, and you can't find a suitable chassis, and then you end up too lethargic to order transformers, and then you buy a car with issues and then get obsessed with fixing that, and all of a sudden, years go by...
Anyway, Tony (still referred to as the Oracle) just randomly sends me a link to this Russian dude selling a chassis that looks remarkably exactly like the chassis I need. I have been half heartedly looking by this point, but not really that hard, and have been put off by the needing to get a custom faceplate. However, this has it all, it is like the miss world of chassis (at this point at least, we'll find out when we start putting shit in it, i mean, parts). So praise the lords of metal, and one click later at 3am half asleep thanks to ebay I've bought it. Awesome.
Anyway, so that arrives, and it is actually pretty cool. May have to drill extra holes, as they don't line up with my board (but if I'd got the boards he is selling it'd have been a perfect fit, so I can't complain, even though whinging about irrelevant crap is baked into human nature). Faceplates look cool too, so it's all good!
Anyway, having got the chassis, I've just placed an order for the transformers from InMadOut, the same source as the ones for the slo clone build. Had them slightly changed, so that I have a 14V tap from the PT to save me adding another small 14V transformer. Whether this is a good idea, I don't know, might be a reason it's separate on the Friedman, but as it's powering relays, probably just some form of cork sniffing. I have no idea, but I guess I'll find out... Regrettably InMadOut wouldn't spray the casing gold for me (probably as they are helping me to not make the amp look like donald trump's bathroom interior) so I've had to settle for matte black instead. Black is good. We like black. It sucks in light, and as everyone knows, black objects go faster and sound better. Fact.
So, what else? I've got to do a order for tube sockets, knobs (either Friedman style or Marshall style I think) and need to get gold tube sockets (not the pins, but the surround, for looks, which will be a waste of money seeing as it's going to end up in a vintage style marshall-esque headshell which has no front grille, but much like a penis extension, I'll know it's there, and that's what matters)
After that it'll be the hate job, ie, putting together the order of components from mouser (or wherever is best now I've fled to Europe), choosing capacitors for cork sniffing reasons, and invariably being over the top and getting components with stupidly tight tolerances that are overspecced. Because, as the Mandalorian says, this is the way.
Anyway, probably be a while before next update, unless anyone gets really excited about unboxing videos, n which case tough, you're going to have to get your weird fetish kick somewhere else, as unboxing videos are invariably awful and an anti-climax (unless, you are that fetish person, in which case most like the opposite)
So anyway, until next time, when hopefully some interesting shit will happen and be written about.
