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Custom Work

This page contains pictures of several projects I undertook in the early to mid 1990s.

EAR 859 enhanced triode mode amplifier – picture taken by Preston Horsepool, Colchester, Essex.

This is the first DIY tube amplifier project – my own version of Tim de Paravicini’s EAR 859 stereo single-ended enhanced triode mode amp back in 1996. It’s a beautiful looking and clean sounding tube amplifier, however was a time consuming project to build. It took three days alone to complete cut-outs in the copper chassis and 1/4″ brass front panel. All wiring is point-to-point and the capacitors are polypropylene, even the power supply smoothing capacitors, which are motor-start capacitors. I love the retro steampunk look of this amp – it would not look out of place on the Nautilus (Jules Verne).

Cascode Tube Phono Pre-amp – picture taken by Preston Horsepool, Colchester, Essex.

At some point I acquired a big box of television tubes from a local auction. I decided to attempt something useful with them and set about building a tube phono pre-amp for my Garrard 401 turntable. Each channel contains two 30L15 frame-grid triodes (an old TV tube). I settled on a cascode input stage, passive RIAA equalization curve and cathode follower buffer stage circuit. I had dozens of these tubes, but had to handselect them because the majority of them were too microphonic. The power supply was housed in a seprarate box to minimise noise and that also used 30L15 in a tube voltage regulator. The reference voltage was generated with a gas filled (argon, I think) tube which glowed a beautiful lilac colour.

Soldano SP-77 Pre-amp in a tiny box – picture taken by Preston Horsepool, Colchester, Essex.

This little box contains the gain-stage of a Soldano SP-77 rackmount pre-amp. The subminiature high tension transformer was wound by hand as none of that miniscule proportion were available at the time – they still aren’t. The transformers were ferro-magnetically screened from the tubes using a steel partition plate. Other titles for this project are, ‘an exercise in miniaturisation’ or ‘How not to operate a manufacturing company!’, as it was another time-eating project. Good fun though and a learning experience.

Modded Fender Twin Reverb Amp – picture taken by Preston Horsepool, Colchester, Essex.

Hot-rodded Fender Silverface Twin Reverb. I rewired the redudant non-vibrato channel on this amp and added two tubes for four extra gain stages to create a lead channel. Also, photo-optical channel switching. In hindsight I don’t recommend cutting the metalwork on vintage amps and modifying them, however at the time it was a cool thing to do – it was great turining up to gigs and seeing the surprise on our rhythm guitarist’s face when this apparantly stock Fender amp amp produced immense, searing, saturated overdrive tones. The power tubes installed are vintage U.S.A. made JAN Philips/Sylvania military grade N.O.S. tubes and have exceptional low self-noise – quieter than any other 6L6 tubes by other manufacturers I’ve tried. I’d always thought that power tubes would not be critical for low noise in amp – you live and learn.

Custom Fane 2 x 12″ speaker cabinet. Photo taken late 1980s

One of two custom-built closed-back speaker cabinets based on FANE 12″ 200W speaker drivers. These cabs were constructed using 3/4″ MDF and fitted with aluminium eges and steel corners, resulting in a very dense and strong cabinet. The closed back construction created a much more robust bass and warm response than a typical open or semi-open back combo.

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