Brown Hound has an impressive retro sound, with a tone reminiscent of valve amps of the 1950/60s. Aesthetically pleasing in style with a luxurious feel to it. Warm but still punchy. I've had so many positive comments about this amplifier.
The amp is single ended 7W, using a 6L6 valve. I have added a switch which switches the circuit from pentode mode to triode mode configuration.
The preamp consists of an EL84 with an added piece of circuitry so that a line out can be taken. The gain switch is a push/pull pot which reduces input gain if required. The speaker cab is fitted with a 12" Celestion Gold speaker.
Using ferric chloride I etched the brass face plate and logo's and covered the cabinet using tweed tolex similar to that used in a 1950s Fender Blues Breaker Deluxe.
The first step was to choose high voltage windings to suit a range of projects. I looked at popular amp projects and chose the following: The 0-190V winding produces around 260V when rectified – great for EL84-based amps. There’s the full 160mA available, so you can run a pair in push-pull, parallel SE or even run in stereo.
The 0-275V winding gives typically 360V when rectified – designed for octal power valves (EL34, 6L6, etc) in more powerful SE amps (15W or so). This also has 160mA available, so it’s also perfect for push-pull amps with lower-power valves, such as the EL84 and 6V6.
The 190-275V winding is also available, and gives around 115V when rectified. This is a ‘freebie’ – a side effect of the two main values I chose – but it adds a really useful option to use in amp projects… …Switchable B+!
With these asymmetrical windings, there are three combinations available to run into the rectifier bridge. This means you can use a 3-position rotary switch to get a switchable B+ supply in your amp. With the ratios given you get:
Full power from the 0-275V winding rectified 360v
Half-power from the 0-190V winding rectified 260v
1/10th power from the 190-275V winding rectified 110v
I also added a headphones/speaker switch and line out for late night playing and recording.