Guitar Amp

I've always avoided a specific 12v electric guitar amp, as I generally do acoustic acts, and anyway, electric bands are noisy and always want more power than is available... normally as mains, too. At least if I supply a guitar amp there's an alternative.

Also, the bright input of the bass amp has sufficed in the past, once we get past the teenage strops of the guitarist, in one case. I don't know who was more insulted, me or the bassist they refused to share with... admittedly it's not ideal.

I only built this as I realised I already had all the bits. The box - more or less a 12" cube with a partially open back - and the speaker, a 10" 50W Celestion guitar speaker were left over in the remains of a home built main amp from my active band days (the top of the box was replaced to allow for the preamp panel and the result repainted with blackboard paint, though). Amp was yet another smallish car booster amp - this one £3 in a car boot sale, I think - and the otherwise potentially hard bit of the preamp was solved by buying a cheap 10W amp from Thomann.de - it was a mains-only version of an amp they also did as battery powered (but a lot less, I was likely to be taking it to bits anyway) - the CG-10X - for £28 you got a 6" speaker, clean & dirty channels, and rudimentary chorus & delay. They'/ve even handily labelled the preamp PCB edge connector with everything I needed - amp, gnd, power - so it was almost trivial to wire all the bits together. I did need to add a capacitor in the audio feed from preamp board to the car amp - obviously unblocked DC, on the output, but that's not a problem.



It's quite an amp - loud, solid sounding, a decent clean sound, and of course the effects to play with - once you've done the Cocteau Twins & Ozric Tentacles impressions it's tempting to turn them off, but they're useful to have, along with the comprehensive EQ. They do a more basic version of the amp (CG-5), the preamp of which would probably do just as well, but this one wasn't much more. One thing I'd like to add is an isolated balanced output for PA use across the preamp output, but one day, one day.

I'm torn, of course, about making use of cheap electronics from China, and buying such things new - it's hard to avoid some times, but it's good to use what you already have sometimes. One alternative thought has been derived from a Laney practise amp, that used a +/-12v supply. Experiments proved that this could be bodged by using a car laptop supply to give +24; connecting -12 to the battery 0v, 0v to the battery 12 and +12 to the laptop supply 24, if that makes sense. Obviously any connections in & out would need to be referenced to the -12v rail (so that you're not shorting out the battery down the earth of an audio cable), but it could work. This way, though, I get more volume that just a practise amp...

new generator

freshly constructed - full details to follow to be part of the website eventually - but note connection box (4 pin XLRs of both genders to allow looping together, also car cigarette lighter socket which will be fed via a regulator, also ammeter on output), have also found some big U bolts to hold the motor down. All folds up neatly, with the motor & connection box tucking between the legs for transportation.

Basic size & construction info;

turbo trainers all from the same supplier on eBay (you'll work out which one if you do a search)

hinged base board approx 12" sq 18mm ply (existing, recycled from previous projects) - painted for neatness

hinges - 2off lengths of 16mm box section steel (sold in B&Q) - hinged on M8 bolts (Screwfix) held on with nylock nuts (ditto) - means they will stay on without being done up tightly (hence along hinge to move). Box steel then bolted to base board with four M6 screws (with large washers & more nylock nuts on the back).

The connection box is a diecast aluminium box from CPC, lid removed and bolted through the base board using M3.5 screws. All that really needs to be connected to each individual motor is a diode (so the current doesn't flow back in to the motor and turn the wheel), but on this one I've added a basic ammeter, which is useful. The connectors are my standard 4 pole XLR, both male and female so if necessary I can loop generators together. I've also allowed for a car cigarette lighter socket, which will be switch in along with a basic regulator - this would allow the unit to be used standalone driving equipment directly. I haven't thought about regulators yet - something about 14v would be useful for battery charging and equipent designed for car use (i.e. big amps), but a more precise 12v would be avisable for less robust equipment, such as radios or televisions that come with a 12v mains adapter, but aren't necessarily desisgned for coping with much more than that.

I've also added screw in eyes to neatly anchor the bungee cord that holds the bike wheel against the skateboard wheel; the board folds up neatly against the turbo trainer almsot flat, the motor & connector box sitting neatly between the turbno trainer legs.

Much respect to Louise & Wildfyre for a very productive day getting these done.