Mottlefeeder

It's doing it with two cabs...

In Audacity, the stretch facility is on the toolbar above 10-11 seconds of the recording. The magnifier with the '+' sign will stretch the whole recording, and the buttons to its right will expand a defined section of the recording. David

In Audacity, towards the right of the tool bar, there are tools to stretch out the recording in time. Using those, you can expand the view until you can see individual cycles. I can see no sign of crossover distortion. You do have some warbling harmonics - the lighter coloured parts of the trace - but I have no idea if that is normal for a plucked string. David

On your pcb picture, right hand side, about half way down - a transparent plastic box with contacts in it. Its job is to disconnect the speaker during start-up, shutdown and faults. Relays to pass small signals tend to have gold plated contacts, and relays for electric motors tend to use tungsten contacts. Sparks can erode gold very quickly, but tungsten is tougher and survives that kind of treatment. Unfortunately, tungsten contacts depend on sparking to clean the surfaces, so if they only get low level signals, they can tarnish and cause distortion. Amplifier builders really need small signal integrity to provide high quality sound, and spark survivability for when they disconnect speakers, but you can't have both so they went for tungsten - also it's cheaper. If you are not familiar with relays, you may struggle to identify which pair of contacts to short out, so it's probably best left alone. David

I've had two amps with distortion caused by the speaker relay - often the relay used was designed for automotive use (electric windows and the like) so that it can cope with the inductive load of the speaker. if the contacts get tarnished, it can create a bad connection. If you still have the pcb out, you could try shorting out the speaker switching contacts and then powering up and connecting the speaker after a few seconds. David

Starting from zero, you could have a faulty speaker, or just one that needs to be run it, so take each one out in turn and press the cone in with your fingers at the join of the cone and dome. Any scratchiness indicates the coil/coil former is touching the magnet, possibly indicating damage in transit. Secondly, leave it on the bench and play music through it - does it still sound distorted? If so, it indicates a possible faulty speaker. Finally, connect up an amplifier, and play a low tone through each speaker, ideally about 20-40 Hz, either from a tone generator, or an mp3 recorded from a tone generator and set on repeat. Keep the signal low enought that the cone moves a few millimeters, but not so loud that you get overtones. Leave it to run in for 12 hours and then try it back in the cab. If you run it in at 20 Hz, you will be able to sleep at night because you will not hear it unless you turn it up loud enough that it produces overtones. David

I've been pleasantly surprised by the Behringer Xenyx 302 USB mixer. For £40-45 you get one mic/line it with 2-band EQ and a stereo line in with 2-band EQ. The audio levels are right for my MP3 player and my laptop, so I can choose my line input with one button press, and drop off as much bass as I want so I can play along. It will record from mixer to Audacity, but I have not yet found a way of playing back an Audacity track and recording a new Audacity track at the same time - it's not something I need to do. David

If you want to cool your hot drink, do you blow or suck? A fan in suction pulls air from anywhere on the suction side. A fan blowing directes the air in a particular direction. If you want something cooled, the fan should blow onto it. David

The amplifier will deliver up to 500w into 4 ohms, so a 4 ohm cab should be rated for that, or used with care if not rated for full power. The amp will drive a single 8 ohm cab at about 250W, or drive two 8 ohm cabs at 500W. The output into a single 8 ohm cab will probably be slightly more than half power due to the power supply not having to work so hard. David

I wonder if that would help me learn double bass? David

Fair enough - my load-in is usually anything but smooth so it colours my view of the world. David

I've used Snark clip-on tuners on a 5-string Yamaha and found that at certain points on the headstock, they do not register the low-B, or take a couple of seconds before they decide to display any note. As others have said, they can be confused by harmonics, so pluck close to fret 12 or tune to the fret 12 harmonic. David

I disagree - looking at the size of the wheels, that is unlikely to cope with a dirt-track car park, rough concrete flooring, kebstones etc. You need something with soft tyres on 100mm (or bigger) wheels. David

I use these or similar - https://www.amazon.co.uk/100x-Professional-Reusable-Cable-Ties/dp/B073WVS45S/ref=sr_1_5?crid=10K0S00X4GH6O&keywords=reusable+cable+ties+200mm&qid=1582219594&s=diy&sprefix=Reusable+Cable+Ties%2Cdiy%2C271&sr=1-5 - plastic cable ties that can be undone and cost a few pence each. They don't stick to each other and at the end of a gig, the number of cable ties attached to the back of my rig tells me how many cables I need to find and pack. David

I'm sure I read - but I can't find it now - that you can tune the damping in a cab just by snapping your fingers in it. If it sounds reverberant, it needs more damping, and if it sounds dead, it needs less damping - the optimum is somewhere between those two. Can any speaker builders confirm that the principle is right? David

No problems with the bridge, but some observations about the string clamp - It is designed with two clamps per string, the one parallel to the fretboard is like a string tree with some clamping action, but the main clamp is on the end of the clamp block, where you bend the string through 90 degrees, and thread it through a hole and tighten a screw onto it. This is not the thin part of the string that you wind around a tuning post, this is the string at full thickness - and some strings don't like being bent through 90 degrees. After losing a couple of strings, I made a string clamp block and trimmed the original string retainer so that the new string retainer sat in the right place to hold the strings. I've added some pictures now I've find them. David Original Modified - Strings with shallow break angle, clamp screws on underside (the pink on second shot is a reflection of my hand; the metal is black)

yes that's the one - it was strung BEAD then, but is now back to EADG.

I built a kit which used an 'Overlord of Bass' bridge/tuner block and it was fine. Several people played it at the 2018 North-West bass bash and no-one thought it bad. It's pictured at the bottom of this page - Andyjr1515 has also used one on at least one build, and not warned people off. There is a half-way house between the Chinese Steinberger clones and the Hipshot or ABM products - Nova, made in Brazil, which you can see via facebook. It is now also being cloned by Chinese suppliers selling on Amazon. The original got good reviews, I haave not checked out the clones. David

Alternatively you could go for the musician's equivalent of a van strong-box using a flight case or similar.

I was joking that a switch that was always on would be equivalent to a piece of wire - moving swiftly on: Toggle switches can stay where you put them, or spring back when released. The former are 'latching', and the latter are 'momentary' or 'biased', and often shown in brackets, so ON-OFF-(ON) would have a centre 'OFF' position, an 'ON' position one way and a spring loaded 'ON' position the other way. Have you looked at the guitar spares suppliers - they might have a pickup selector switch that would look the part and make the right connections? Alterntively, could you incorporate a push-pull switch into one of your pots to give you the functions you need? As a last resort, if you have a scratchplate, do you have room for a rotary switch under it? David

It's verry tempting to suggest using a piece of wire... David PS no joy at Bitsbox, Rapidonline, Switch Electronics or ESR

There is a big difference between concealing something, and chucking a blanket over it so that its outline is still apparent. According to Insure4music, concealing a wallet in a glove compartment would not be acceptable, so I question why putting a blanket over something is acceptable. David

The bootspace in a hatchback is accessible by breaking a side window and pulling the seat-back down, and the roller blind cover of an estate car bootspace is similarly not lockable. Does that mean that you do not insure gear that is in the bootspace of an unattended car unless it has a fixed rear seat and parcel shelf? Also, if I try and improve the securty of my hatchback by putting a plywood bulkhead and roof into the bootspace, it would be more difficult to remove any items except through the lockable rear door, but the bootspace itself would still not be a locked enclosure, so does that mean its contents are still not insured? If you are prepared to accept modifications to improve the securuty of the bootspace, what thickness of plywood would you deem to be an accceptable deterrent? David

Glad you like it - the Eminence website has a similar design using round vent(s) if that is easier for you. David