JapanAxe

Installed some of the hardware. I hate wrestling with bear-trap retainers but not as much as I would hate the sound of a broken KT66 rattling around inside the enclosure. I haven't fitted screening cans for the preamp valves as this is a fairly low-gain design and the enclosure is one big Faraday cage. Also wired up the circuit board. Some of the eyelets are as yet unsoldered as they will take leads from the transformer.

How was my gig last night? Rather lovely, that's how it was. Wedding celebration in a teepee-style marquee, in the grounds of a farm-cum-wedding-venue. Bit of a hike from the car park to the teepee but we were well looked after by the organiser and of course the weather was lovely. We optimised the space by putting the drums off to one side - we're all on in-ears anyway.

'Must be willing to dress up a little bit crazy' - but not too crazy, don't want to upstage Julian do we? 'The band's image is that of a gang of individuals' - who are so individual that they all have long hair. 'Will best suit somebody who doesn't mind that they aren't the songwriter' - you won't mind making zilch from publishing, even if you came up with the killer bass line that everyone hums when they think of the song. 'Location: Camden, London' - where dreams go to die.

Ah yes, the old comedy somersault over a wedge monitor! With subs you may as well display a sign saying ‘stick your glasses here’.

Just clocked the price of the new LB - ooft! 40cm wide sounds good, around 15¾inch in old money.

'Age 22-40'. My age will soon be 22+40. I have long hair but like Happy Jack I don't usually wear it.

In pubs with an open ‘stage’ setup I sometimes have to remove punters’ pints from the top of my amp!

I’m a bit conflicted on how to vote! Yes I’d love a small-footprint 100W valve bass amp but I’m well into a 50W build and I have to be realistic about what I can fit in my kit cupboard… Actually the footprint thing is a significant issue for me. My bigger cab is a BF Super Twin which is 19” wide, but many (if not most) valve heads are much wider and I can’t tolerate the overhang. Hence the home brew solution.

Blimey!

What were the circumstances that led to this?

I think the @Chienmortbb is hoping there won't be smoke

Marked, punched, drilled and de-burred all the holes in the top surface of the chassis. That's a lot of holes! Also fitted the grommets for the transformer lead holes. Oh yeah, fitted the feet to the bottom plate.

DIY Ampeg B15 head into a BF One 10. 22W of vintage tube tone in my music room, although the Origin Bassrig ‘64 has been getting a lot of love lately.

Valve socket holes cut and mounting holes drilled.

Last night and this morning have been all about metalwork. Never my favourite subject at school but it just has to be done. The big challenge here was cutting a rectangular hole in the rear panel (0.91mm steel - about 28 gauge for our US friends) to fit the IEC mains inlet. I started with a 6mm hole inside each corner, then took out the bulk of the material with a 20mm panel hole cutter. I managed to remove some more with a hand nibbler (yes it's a thing!) before defining the edges with a cutoff disc and a grinder on my Dremel-a-like tool. I'm pretty pleased with the result. That's all the front and rear panel holes done, plus the mounting points for the eyelet board.

My current bass heads include Class AB (both valve and solid state) and Class D. Each is a good example of its type and I enjoy playing them all. I see no value in generalisations based on personal preference. If something works for you, that’s a win so go with it.

Made some progress on the board: (1) Covered the board with sticky paper recycled from an eBay label and marked out all the positions of eyelets, mounting holes, and bias pot. (2) Drilled all the holes. (3) Set the eyelets. I ended up moving one because I thought it was a bit close to its neighbour, given the 720V between them! (4) Fitted the stand-offs and the bias pot, straightened some copper wire and soldered the earth bus in place.

In 30 years of using it I have come across a no-earth situations 3 times. In 2 of these the solution was to run an extension from a good socket. In the last it was an outdoor stage so I got the organisers to create an earth by running a wire form an earth pin plugged into one of our socket strips, to a lamp iron driven into moistened ground next to the stage. It worked and the show went on.

I always carry a ring main tester (a few quid from you local ToolFix ScrewStation). Plug it into a socket and if all 3 lights come on you’re golden. Anything else indicates a fault, most commonly live and neutral reversed (be afraid) or no earth (be very afraid). In those (rare) situations the venue should be made aware as it their potentially lethal problem to fix.

Yes I'm aware of that. I use the PDI09 with valve amps rated at no more than 30W and always with a speaker connected. I'm wondering if it will roll off too much low end to be useful for bass, but there's only one way to find out!

I use this plugged into a speaker output of my guitar combo but never tried it on bass. Time to experiment…

There's been a bit of a hiatus in this build for a couple of reasons. First off I had a run of 4 gigs and 3 rehearsals, followed by a 2-day trip up to Liverpool to play the first ever David Bowie World Fan Convention! Secondly, the PT secondary hits 360V AC unloaded, which would translate to about 509V DC. The standby arrangement leaves power applied to the first filter cap, which is rated at 500V, so I have obtained some smaller 450V caps to use in series (with balancing resistors) like Fender did in amps such as the Twin. The original JTM45 design employs 32uF filter caps at the first two nodes, whereas this design has 100uF at each! Two 100uF caps in series will give a total of 50uF at the first node, so I bought 4 in the hope of doubling that. I can only fit 2 on the board but if the smoothing turns out to be inadequate (unlikely!) I can possibly piggy-back them on the 2 that I'm installing (left of the circuit board). Today I finished drawing the layout. I'll check it again tomorrow, then start marking the eyelet board.

I find that even 1 pint affects my concentration noticeably, and hence my playing and my driving. On gigs I stick to soft drinks or tea/coffee if available.

One gig was about 2 hours away, the others no further than an hour. No chance of a medal for me then?

You lightweight Tim! Thursday - guitar with a Stones tribute Friday - rock’n’roll guitar Saturday - country bass Sunday - rock’n’roll guitar Monday (tonight) Tuesday Wednesday - Bowie tribute rehearsals (guitar)