I have been thinking about my first amp build. I am looking for something basic to experiment with. I want something with a tube rectifier just because that is what I want to try. I have looked at a lot of "Champ" type circuits but feel like I would miss TMB control. The P1 circuit over at the AX84 site looks like it would be nice to try but it has no tube rectifier. I am pretty sure that I could build a power supply section that would give me the appropriate bias voltages and use it. I used to be an engineer/scientist and still remember the basics.
Here are my questions.
1. Does a tube rectifier (or lack there of) make any tonal difference?
2. For those of you that have built amps without TMB controls, did you miss them?
3. I have a rackmount electronics chassis that I plan to use as a test bed untill I have a circuit that I like then I will build a more traditional cabinet/chassis for it. Has anybody else ever tried this? It might be neat to lay it out in sections and modify each as I learn more and curisoty leads me.
1- A tube rectifier affects the dynamics of an amp; it makes the power supply "sag" under current demand and thus change how the amp will sound.
There is no advantage to use a tube rectifier with a Class A amp like the P1.
2- I have an 18watt tremolo head with single tone control and it does the job.
3- I do not know about this but I guess it is feasible. I would be nice to have some kind of universal power supply that could be used in different prototypes.
1) A valve (what's a tube?) rectifier can make a tonal difference on some amps. Not on a single-ended amp (like the AX84 P1), though. The valve rectifier drops a little voltage when the amp's at idle and a bit more if it's a Class AB amp, cranked and you suddenly demand more current from the PT for transients. You can emulate this behaviour with a 50c resistor if you don't have a valve rectifier (or the filament winding for it, or the centre-tapped HV supply that you need for one).
2) On some amps the TMB thing is really not needed. A Marshall 18Wer or Tweed Deluxe, for instance. On other amps, it's there to help dial in a much wider range of tones (Soldano SLO, etc). You will eventually have to build at least one of each. It's the law
3) Should be fine. Draw it out on paper first and see that you don't have any component clashes or potentiually problematic lead dress (e.g. due to OT positioning). Maybe plan ahead and think up a layout that's as complex as you think you'll need.
Good luck
in the wilds of Borneo, and the vineyards of Bordeaux, Eskimo, Arapaho, move their bodies to and fro...
3) Should be fine. Draw it out on paper first and see that you don't have any component clashes or potentiually problematic lead dress (e.g. due to OT positioning). Maybe plan ahead and think up a layout that's as complex as you think you'll need.
Good luck
THAT is indeed some very good advice. What saved my ass was actually making a cardboard model of the layout (drawing everything out on an actual size piece of cardboard), complete with tranny cutouts and tube (sorry...valve) holes and front and back panels. That really lets you get an idea of the scale of things, and if there are going to be problems with the layout of the components.
