In my callow youth I built one of this using point to point wiring because I couldn't afford the pcb. Cleaning up the basement I found it.... I carefully brought it up and son of a gun it still worked. It has a 100R trim pot for bias adjustment, I searched and couldn't find the article anywhere so I'm not sure how to adjust it. Does anyone know? Thanks in advance.
The emitter resistors are 0R56 so I went for about 15 mV, they balanced reasonable well - a few mV of each other.
Thanks for the input, I'm going to play with this a bit more.... I would love to find the original schematic though.
I built one in the early 80's using a kit from Audio Amateur, stuck it in a Dyna 120 chassis using the Dyna power transformer and found it to be somewhat better than the Dyna circuit.If circuit boards could be found I would like to build another,I could make the boards but the idea of having those chemicals in my kitchen as I once often did is just not possible today.Cheers.
Hi,
This brings back memories of great sound from about 1970. I had built Mullard 5-20's and taken them to a hifi friend's place; he had Williamsons. The Mullards were upper middly and lacked the delicate treble nuances of the Williamsons; class AB el34's U.L. v.s. kt66 triode connected. The Mullards were quickly converted to Williamsons and enjoyed for 20 years. They later ended up with kt88's triode connected (power tranny just big enough) and remain this way.
However!! my Hiraga class A transistor amps sound even better. Quite a journey
The schematic is from 10 years before Quad. Circa 1948.
I think the Quad has a few Williamson features.
There is obviously confusion here with the "Williamson" label. The OP Williamson design is a solid state DIY amp. design by the editor, Reg. Williamson, of the U.S. "Audio Amateur" magazine issue of April 1979 - long after the Iconic valve amplifier design demonstrated by Williamson ca. 1948. Just read the thread fully and check the schematic and attachments properly. All is revealed.
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Looks a lot like the Ekektor ‘Equa’ amp. It was the first amp I built in about ‘75 or ‘76. Sounded good!
Elektor's EQUA from 1970 featured a Vbe multiplier for biasing the output devices and two CFP's in the output. So there's quite some difference. Yes, EQUA sounded fine, but lacked ruggedness.
Best regards!
Best regards!