Mottlefeeder

Filling in some of the background, when I started the revamp I considered the electronics recess on the back of the Mk 1&2 and whether I could fit in 'Treble, middle and bass' on one row and 'variable HPF, swept mid-frequency & variable LPF' in a row below. But when I thought about it, I already have EQ on my basses, and I tend to leave the HPF set to suit the speaker, so I was able to curb my enthusiasm and go for a simpler option. - one hi-Z input stage with switched gain, followed by an 18dB/octave fixed HPF to suit the speaker, with a volume control between that and the amp. The only frills were a tuner out and a live/tune switch. Having made that decision, I then realised that the recess I built in for the electronics would be a tight fit for two jack sockets and the circuit crammed in between them, especially since I could not use the space under the overhanging control panel supports. To minimise the number of items on the control panel, I had to ditch the live/tune switch. The tuning jack socket is now always on, and can be used as an emergency 'DI', and you turn down the volume for silent tuning. I also opted for a combined power switch and volume control - a bit retro but it also solved another problem: the switch-off transient that blasted out from the Mk 2 is effectively muted by turning the volume down before switching off - simples. Another problem with the Mk 1 & 2 was that the peak current drawn by the amp was enough to pull down the voltage of the battery to the point where the amp momentarily tripped out on low voltage. Fitting a bank of 10 x 1000mfd capacitors in parallel with the battery seems to cure that problem. David

They are are gone- recycled a week after the first post. David

Thanks for that - I may have a problem that could be solved that way. My experience to date has been fabricated structures made from Plasticard. David

One problem with the Mk 1 & 2 was the positioning of the battery hatch, so this was the first thing to change. The original design had the battery in the speaker enclosure with an air-tight door (as PJ does in the briefcase). Keeping the battery outside the speaker enclosure, and allowing for a choice of battery depending on the required power and duration meant that the box would be bigger. Also, keeping the speaker enclosure volume the same as the Mk 2 but moving from 9mm Birch ply to 12mm Poplar ply also increased the volume. With the help of a spreadsheet calculating all the volumes, I found that the overall box size would increase by about 10mm in all three dimensions. The Mk2 layout - The Mk 3 layout - Battery access from below - One of the advantages of putting the battery outside the speaker enclosure is that I can have a cable route from the battery to the outside world without it having to be airtight. This will give me the option of using a mains power supply with an IEC male 'kettle connector ' on a short flying lead. One disadvantage is that all my battery packs have to be modified from 'fixed socket on battery' to 'flying lead socket on battery'. David

Having staggered to the end of this project in 2021, there were a few niggling problems - 1) The Mk1 was going to have a battery hatch on the back, and a class D amplifier module built in to a cavity on the back. The chosen amp module (Ebay) turned out to be very noisy, so I decided to replace it with a larger module hanging on the back, which preventing easy access to change the battery. This was the basis of the Mk2. 2) The Mk2 had a simple preamp containing a gain stage and an HPF, but it produced an annoying click as the compo was powered down. 3) The Mk2 was limited to battery power only, unless connected to an external mains 12-14v power source. The Mk3 is a rebuild intended to fix those issues and add some further benefits. David

Reading the synth/mixer/shock sub thread, I wonder if the mixer connection was by jack or XLR, and whether the shock could have been caused by phantom power being connected to the signal lead in some way? David

Kev was freecycling several packs of mic wind shields. I asked for one and it arrived promptly, no charge for postage either. Thank you Kev.

It is also worth checking where the centre point of the fan is. On my Ibanez 5-string it is about the 5th fret, which is also my normal cage position, so the transition is very easy. If you often play down by the nut, your transition to fanned fret may take longer. David

I busk in a band fundraising for Cancer Research UK, and we have to do risk assessments for every gig in order to be comply with their insurance requirements. It's mainly common sense - Typical hazards are: 1) Cable routes not thought out - keep as many as possible out of the performance area. 2) Gear falling onto people - less of an issue if it isn't your PA. 3) Electric shock - test gear regularly and visually check each mains cable as you set up. 4) Audience members on stage (invited or not) - higher risk from trips and falls & probably not covered by your insurance, so no audience on stage. 5) Crowd surfing...etc David

Gone to recycle centre.

My daughter's printer has just died, shortly being switched on after a period of non-use. Annoyingly, she had just replaced some of the cartridges. The printer is not economically repairable so I have eight new / almost new / part used cartridges that could be re-homed. Yours for the cost of posting them second class. David

Anderton's write up does say that the fretted version is shown 'for illustrative purposes' David

To reduce water usage by your loo, the recommendation used to be that you put a brick in the cistern. You could use something spherical so it did not flex, and hollow so it was light - a tennis ball or two? David

I've seen two styles of battery box, a) conical springs point in through the end of the box, in line with the battery terminals, and b) curved spring contacts sit at the bottom of two pockets which are sized so that the battery terminals only fit in one way, so it is impossible to connect the battery the wrong way round. 'b' seems to be a much better way to go. David

Heavy duty battery clip https://www.bitsboxuk.com/index.php?main_page=product_info&cPath=192_194&products_id=1428 David

My understanding, from the comments of an independent retailer, is that having stock you don't own on display improves your sales, and then you also get commission when you sell the stock that hasn't cost you anything. If you are selling into a niche market, go to a specialist in that market and accept they will take a cut. David

It may be that those manufacturers want to mimic the look of Marshal / Vox / Hywatt / Wem cabs from back in the day. Several speaker builders on this forum have used speakergrills.com, so that would be a fairly safe option. If you investigate other suppliers, check the thickness of the grill they offer. David

There are speaker grill manufacturers who will produce a grill to your dimensions - eg www.speakergrills.co.uk Before going down that road, you need to consider how you are going to fix it to the cab, whether you want a flat grill, or one with folded over edges etc. I would also recommend having it coated before despatch. You will waste a lot of paint spraying through the holes if you do it yourself. The alternative, if it exists, is the aftermarket you refer to, which may be more expensive because each product is intended to fit an expensive branded cab. David

I had a s/h Warwick Corvette fretless tuned BEAD, which I loved, and decided to move on to a 5-string fretless Corvette. What I didn't realise was that the transition from 4-string bubinga body to a wider neck 5-string and lighter swamp ash body would result in neck dive. I tried various remedies and eventually decided I would never be happy with it so I moved it on.

It may depend on whether the amp module is stand-alone, or on the same pcb as everything else. When I fried my Ashdown MyBass, I did some basic tests for them and they then sent me a new module and asked for the old one back. That suggests some component level of repairability is feasible. David

I have a Tascam GT-R1 recorder/bass trainer with stereo mics built in, but found it overloaded at performance sound levels. Conversely, a cheap Tandy electret mic feeding into a budget mixer worked fine at the same volumes. YMMV as they say. David

Things like the Phil Jones Briefcase are available second hand, using mains or a 2.2kg 12v lead acid battery, so they are a one hand carry, but not that light. I hear that the next generation used a lithium power pack which is lighter. but much more expensive. David

A box that includes different size holes for the battery terminals would tick the boxed for me - no chance of inserting a battery rhe wrong way round and damaging the circuit. David

That one was two shielded balanced pair cables with a common figure-8 sheath - presumably someone still makes it. David

As a compromise, Studiospares did a figure-8 stereo microphone cable - two balanced cables joined together. Haven't found it yet on the G4M site... David