Tools, Tones and Toys for Guitarists
Picked up another Bell & Howell Gaumont today, with the speaker cab – a Model 601 from 1950 (based on the capacitor dates). Nice to see the original speaker still in the cab – I gave a quick test, sounds fine. The 601 is the same amp as the 621 (full details here). The 601 … Read more
Just one of my little side projects – it’s a pretty hot day here, so not one for playing with germanium transistors in a big black box with a tin roof (also known as my garage / workshop). The leakage goes nuts, and they sound like balls… While playing around with a bunch of old … Read more
Just a little fuzz face variant from D*AM – the Maggot Brain from 2019. There are some more recent variations on this as well. Could not see the cap and pot values, so just a partial trace. Being a fuzz face, you kind of know what they might be. I mostly breadboard before building a … Read more
OK – so this is what happens when you agree to make a pedal, before knowing what someone might ask for. I’m not sure that this is 100% my kind of thing, but here it is. Yes it’s a huge layout, but it is going in a 1590XX enclosure, so why not. I started this … Read more
This was long overdue – I finally got around to making a half-decent wiring rig. I’d been using cardboard from pizza boxes (yes really), which worked, but it was pretty ordinary to say the least. Once the parts were laid out and the enclosure marked up, I drilled the pilot holes in the chassis, then … Read more
GIBSON GA-30 GUITAR AMPLIFIER SCHEMATICS This is one of the GA-30 amps – there were a few by the sounds of it. While they share a similar topology, there are clearly some differences from the one above. Apart from changing the circuit, their appearance also varies over time – I’m not going to try and … Read more
6SJ7 preamp, 6SN7 paraphase inverter, 2 x 6V6 with local negative feedback. GIBSON BR6-F GUITAR AMPLIFIER SCHEMATIC Clearly a bit of work has been done on this one – just using the pic as an example of circuit construction. Low impedance input 6SJ7 PRE Ra 220k Rk 2k2 20u bypass Screen 2m2, 50n bypass 10n … Read more
5879 pentode premap, which is an improved version of the E8F6 – uses a Vox style cut control across the plates of the phase inverter. Paraphase inverter, driving 2 x cathode biased 6V6. GIBSON GA-40 GUITAR AMPLIFIER SCHEMATIC
Ignoring the gigantic and overly complicated trem section – this is one of my favourite sounding AC amps, which is most likely the inspiration for the Matchless DC30 pentode channel. VINTAGE VOX AC-15 SCHEMATIC Version: NO V-1-5 / OA/031 Apparently this schematic is a v3, redrawn by Thomas Organ, with some different component numbering. … Read more
The Vox AC6 is a departure from the Vox AC2 & AC4, in that it has a 12AX7 preamp, negative feedback, no trem, and for some reason, the tone control is before the first triode – it’s a bit of an odd-ball in the Vox lineup from the time. The 12AX7 preamp arrangement would give … Read more