18Watt.com

ViperDoc wrote: ↑

Wed 02/02/22 12:25 am

I'm no expert, and this may not be an issue, but your DP3T wiring changes the phase of the HT pair throughout the series. It's simple enough to wire them in a linear arrangement to enable a low-middle-high voltage design that retains the phase as below:



I'm interested in the brain trust's opinion. Looks like a cool option, especially the maintenance of full voltage on the preamp.

Thanks. The phase thing appears not to be any trouble. It works perfectly...
I don't think the double rectifier will be an option.. I have a bad feeling about that.
Anyway, I don't mind not having tremolo at 2W switching... and the amp sounds great with this attenuation anyway, so for me it's not necessary to only scale down the power amp.

But it got me thinking... when you use a normal 18W power transformer 290V-CT-290V.. you can apply the same logic and use the CT and one HT terminal to attenuate the amp at B+ level
One would have to use a FWB rectifier tho...

By coincidence on my bench after a repair is a Tiny Terror. It has a two step power transformer which is described as 15w/7w. It is a simple application to all stages by switching the whole supply from the transformer. It works ok to manage high gain without quite so much volume.
This is actually quite a good amp with better (and well anchored) board than most "foreign" pcb amps. After two days of chasing an intermittent it was a coupling cap defect.

Dd

Daviedawg wrote: ↑

Wed 02/02/22 3:23 am

By coincidence on my bench after a repair is a Tiny Terror. It has a two step power transformer which is described as 15w/7w. It is a simple application to all stages by switching the whole supply from the transformer. It works ok to manage high gain without quite so much volume.
This is actually quite a good amp with better (and well anchored) board than most "foreign" pcb amps. After two days of chasing an intermittent it was a coupling cap defect.

Dd

Yes, so simple and obvious..
Well, I could try this experiment by putting in a FWB rectifier and a DPDT switch in one of my 18/36 watt amps. It's not a lot of work and if the result is nice I'll let you know.
This means that on all amps with a HT center tap can easily be equipped with a satisfying half power switch..

That's a really cool idea!