This week I finished building two amplifiers - a Ruby+ and a Classic 50 - my take on a Hiwatt DR504. As part of the test process I give my amps a 'road trip'. This weekend I have three gigs lined up in London so the timing was perfect. So as not to mark the customers' cabinets, before they hit the road the chassis are put in test cabinets.

Giving the amps 200 miles of vibration in the boot of a car, a couple of gigs and then another few days of testing on the bench back at base is the ideal way of revealing any issues before the customer takes delivery.

The Ruby+ is a 40 watt head with Reverb and a six position Headroom Control. It has a four position switch which offers the following voices- Bass Light, Mid Focus 1, Mid Focus 2 and Deep. The player can fine tune the voice selection with the Tone control which shifts the emphasis between mids and highs. A two button footswitch with 8 metre cable and rugged XLR connectors allows for switching of reverb and 'more', a fixed amount of boost. Simple.

This amp is for players who love their reverb. The reverb on the Ruby+ has a colour control which adjust the amount of sparkle in the reverb tone. There are also two rear panel features associated with reverb that work in conjunction with the foot switch. The four position Interactive Reverb switch offers the player the following options: Long Reverb time, Short Reverb time, Long with More selected, Short with More selected.

The second feature is a three position switch that offers three levels of 'off' for the reverb, so the player can use the footswitch to dim the reverb level rather than turn it off completely.

None of these features would be worth having if the reverb wasn't first class to start with. The studio quality reverb offered in 633 amplifiers, is an original design which uses compression and soft clipping to produce lush warm reverb tones without the boing and clang of spring units.

In complete contrast to the Ruby+ the Classic 50 has no reverb, no Variable Headroom and no footswitch. It doesn't break up early and puts out over 50 watts of clean power increasing to nearly 70 watts when the power stage is saturated.

When I received the email asking me to build a copy of a Hiwatt, my first reaction was to say no, there are other companies building Hiwatt clones and it's not really my thing. But the customer persevered and explained that he wanted an amp that was built locally, not one sourced from the states or built from a kit. So I agreed to build it on the condition it would have 633 looks and a few enhancements for ease of use and reliability with modern valves.

Looking at the front panel the obvious difference from the DR504 is that I've combined the two input channels into one so that it's not necessary to use a jumper cable. The Bright and Normal volume controls still work completely independently as unlike in the Marshall plexi design they are individually buffered.

The Hiwatt tone stack is a variation on the traditional Fender design. Note the original Hiwatt layout of Bass-Treble-Middle has been retained. The Presence control is interesting, varying the amount of top cut going in to the power amp as well as the amount of high frequency negative feedback. Unlike all my other builds this amp has no variable headroom but it does have a Master Volume which makes it possible to get some pre amp distortion when the pre amp volume controls are set high. After playing my Variable Headroom amps running at around 15-25 watts for the last two years it will be interesting to gig this one. It's definitely one for pedals so I've brought along my prototype 633 Chipotle overdrive and the MXR Prime Distortion for the heavier stuff.

Watch this space for the post gig report.