The Amp Garage

The Tone Master is a solid state amp, isn’t it? Solid state amps can be operated with a high impedance load and won’t cause any damage. It’s when they are operated under their rated load capacity that causes problems. Example: 100 watt @ 4 ohms rating. Don’t attempt to operate it below 4 ohms like 3...

On the back of the IEC receptacle is should be labeled “L” line( hot), “N” neutral and “G” ground. The red inside the amp id assume was hot, black neutral and the green with yellow is earth ground.

With choke input filter arrangement, you’ll get about 350 volts rectified DC.

Adding a bleed resistor to the first filter cap can help with the rise time and “amp on” behavior but it’ll never be completely silent. I’ve done this same addition before. I use a 1Meg across the switch and a 470k bleed resistor.

Your third picture in the last waveform post is what’s going to be going into the phase inverter with no master volume and the output will be muddy by that point. The cold biased stage is really for gain control in these amps. The power section is full square wave before any preamp clipping. Because...

Plate and screen voltage are high along with the low cathode voltage. I’d check the ground connection of the cathode unless you were checking the cathode voltage at a different chassis reference point than the ground lug for the cathodes.

I hate to say it but having the output transformer that close to the preamp tubes may create problems.

In general, how does one determine the rated output power of a tube amp? In my particular case, I am looking at a pair of EL34s vs a pair of KT66s in a push-pull configuration. At a high-level, both of these tubes are rated for 25 watts dissipation; so naively, one would think a pair would make for...

I notice that there’s no coupling caps before the 330k and 100k mixing resistors originally. Are you 100% certain that the signal bleed you talk about is not a normal condition of the amp?

The Trainwreck is about 482hz.

I’ve never actually heard crossover distortion in a tube amp but I’ve observed it many times while watching the output waveform. On a tube amp it’s usually subtle and right at the point of clipping and never gets to be more than a slight turn in the center point of the sine wave until clipping is he...

I built an amp with 3 12ax7 and 2 EL84 using that transformer. It didn’t sweat it. Like I said before it’s the HT winding that’s saggy.

I think the heater supply is adequate for what you’re asking. The HT winding is kinda saggy and using it for more than 2 EL84 or 2 6v6 would probably not be advisable or I should say maintaining the 8k output transformer impedance would be best.

A Trainwreck Express with el34 has a harmonic content that fills the room giving the perception of volume louder than the actual power output. I am going to have to say that you most probably haven’t played a 100 watt Marshall through a 4 x 12 or a full stack. I say this because while a Trainwreck i...

I just hook the transformer up to 120 volts ac through a variac and test secondary voltage output after doing simple resistance/continuity tests for verifying no shorted windings and confirming wire/winding groups. I’ve heard something about the bulb test but you’re kinda making it act like an ignit...