• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

A couple newbie questions


2010-11-16 11:22 pm
I'm in the process of gathering parts for my first stereo amp. I've built a good number (say 20) guitar amps. However, I have a concern about grounding issues. My plan is to build a preamp and two monoblocks. If I use three prong plugs on each piece of equipment and then shielded cables running back and forth from the preamp to the monoblocks....isn't that going to create ground loops? What can I do (ahead of time) to prevent and/or reduce the possibility of ground loops.

Question number 2...

One of the rules among guitar amp builder is to put the transformers as far apart as possible. However, I see home-built and commercial amps with the transformers REALLY close together. Granted the laminations are oriented at 90 degrees, but close. Do I need to worry about the OT picking up any interference from the PT?

Interference between transformers is always possible, but 90 deg orientation helps a great deal. Stereo OPTs are generally higher quality than guitar OPT, so may have less stray field/pickup.

The fact that you have asked this question shows that you are already thinking about the right issues. One big difference between stereo amps and many guitar amps is that stability is achieved by careful layout and screening, rather than huge grid stoppers.