The Whisper is my very first scratch built amplifier (5/03). I was collecting parts to build either Doug Hammond’s “Pentode Driver” distortion pedal or Bob Stewarts “Spud” (single tube) when I came across LT Spice on Duncan’s amp pages. Modifying the single ended amp that he shared, my design looked as if it would operate on very low voltage(<40volts), providing a safe first build to cut my teeth. Not wanting to waste any of the nice red board material on a project that seemed destined for the garbage. I threw the circuit together on 1/16 wafer board that I mounted inside a Premier phone base (Premier was the brand amp Link Wray used, Fate? Irony? Stupidity?).
The hybrid turret/point to point layout was something else I have never seen but wanted to try. Works pretty well, but I’m not sure it would work for a complex amp.
I use
d chassis mount sockets on the wafer board. 1/16 wafer board doesn’t provide the most stable platform for wire-tie mounted tube sockets- but this thing wasn’t going to work anyway, right? -Most of the bad things I have heard about (PC) board mounted sockets has to do with cracked traces. I figure 1/8 FR-4 or G10 is as rigid as aluminum and board mounting the sockets allows for greater soldering iron access/angles than point to point inside a chassis. Flimsy whaafer-thin board will also break solder joints after a few tube swaps.
Probably the kludgiest part of the design is my tube selection. The pre-amp tube has 1.4v heaters and the power tube has 6.3v heaters. I used separate batteries, but will eventually rig this thing to use a single heater supply and regulation, will probably reevaluate the the whole thing at that time.
Sample of the amp: Soon after building this amp a former bandmate asked me to help him fix up a recording for an Italian instro-compilation. The original lead track wasn’t quite in sync to the live performance. So my friends asked me to add my own out of sync track !
“Where…” tune from the musical “hair”