pedalpa.org.uk
bass & guitar instrument amplifiers

PA Services
-large system
-small system
-musician info

12v PA info
-bike generators
-power control & batts
-connectors
-amplifiers
-speakers
-mixers
-gtr & bass amplifiers
-lighting
-misc kit

domestic 12v info
-generation
-storage
-equipment

lower voltages
-6v systems
-USB/phone power
-wind-up devices

links

about/contact

electric guitar amplifier

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 is 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 sometimes.

Note that this preamp includes a mic preamp; I plan to add a mic socket in the rear of the unit, again to add flexibility. Like the bass amp, a DI socket to take the feed directly into the PA would be useful too.

(Alternative thoughts were using a useful little Laney practise amp, that used a +/-12v supply. Experiments proved that this could be run 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. It's alwasy best to use what you already have, if possible.) bass amplifier

If an electric bass is being used with a band it can be useful to have a separate amplifier; it requires a significant proportion of the total power; where limited power is available, this would affect the quality of the amplification of rest of the band. Where possible, this amplifier is used with a separate generator and smoothing battery.

Sadly, not a real Marshall combo: the case is an empty guitar head bought at a car boot sale. It contains a smallish car audio amplifier (max 100w rms into 4 Ohms, approx 70w into 8 Ohms) and a custom built pre-amp; the main channel has 'flat' and 'bright' inputs (via an extra preamp that gives a 'presence' peak to make electric guitars sound bright), gain, and treble & bass controls. The second channel has gain only, both channels controlled by a master control (which has a direct stereo input at the rear, also allowing the amplifier to be used for amplifying recorded music). This has proved to be a flexible amplifier; the flat channels can be used for acoustic instruments and even microphones where necessary, and the bright channel gives a good sound for both lead guitars and electric bass guitars. This amp is normally used with a 15" speaker in a closed cabinet for bass & guitar use, although it can also be used with a stereo pair of speakers for small PA use.

This amp has a custom-built preamp, driving a car radio booster amp. The amp can be run in mono or stereo mode; in normal use the amp is run bridged, but stereo outputs are also available if the amp is used to run a small PA. Stereo phono intputs are present (don't have their own control, but are affected by the master volume control).