The Amp Garage

The only really good reason to use CCs is when working on an old amp, in order to satisfy a nut job authentic-original fetishist. :roll: There is some evidence that CCs produce 'good' harmonic distortion, but only when used in high voltage audio amplification, i.e., plate resistors. I like 1 w carbo...

i believe a couple are power supply dropping resistors. they are 1 watt 220k and connected to both +/- ends of filter caps They are simply voltage equalizers (and bleeders when the power is off), and have no effect at all on tone or response. Any one watt resistor will do, and flameproof is always ...

> My designs are not like the usual.

You can say that again - very cool enclosures.

pdf64 wrote: ↑Fri Feb 04, 2022 8:17 pm eg it might be doing this -

+1 - particularly given your description that in only happens when starting with silence, not when picking continuously.

When the control wiper is at ground, the effect is minimized. There is always some fraction of NFB happening at even that setting, but it's no longer a band pass/band reject filter.

The expander circuits are just twin-T bandpass filters between the plate and grid of their respective stages. Because it's a form of negative feedback, they work backwards from a normal 'T', i.e., increasing the expander control resistance to ground creates more of a mild notch at the T frequencies ...

Yeah, it's mainly for the first cap, although an additional 220uF 100 ohms away will also affect things. The spec is about peak current, which is proportional to the amount of electrons needed to fill that cap up to normal from zero.

They're probably providing the useful DC output current that can be expected using the transformer with the normal rectifiers and caps, etc. In some ways that's more useful then the AC spec, which as your sheet demonstrates is usually different than the actual DC current it can supply.

We are regular customers of Heyboer, and they've been jammed lately by both supply issues and labor issues (unable to hire people to do the work).

The advantage of being a manufacturer is you can have transformers built to spec. :) A power transformer with dual secondaries would let you switch between two widely different power supply voltages, a 'normal' one and a much lower one. Unfortunately, I don't imagine that a HALFWATT :) would sound v...

> 2 or 3
Exactly. Use as many as needed but no more.

Hylight used the same preamp in every amp they made, 50 to 400 watts, so it would certainly work in a 20 watt. If you use EL84 outputs, you may need to attenuate the PI signal a little (due to their slightly higher gain). I am not aware of how the Doncaster Hiwatt folks do their real low wattage imp...

Roe wrote: ↑Wed Nov 17, 2021 8:05 am for the screens a much lower voltage rating is necessary, ie 450v

Good point.

That's where the series voltage dropping resistors normally go (between the can caps).

200ma won't hurt and might be easier to find. Mind the voltage rating, though - 700-750VDC