Tooling up for a build, all my dumb questions in one thread

[Chuck H]

Shouldn't there only be significant phase shifts if the filter includes a load? I'm not looking at the schematic right now. But even in the case of less than ideal phase there is still some of the desired effect with additional wave form distortions. For better or worse. Why should it need to be perfect? Guitar preamps aren't for pure, low distortion reference listening. They're signal processors intended to modify the guitar signal.

[The Dude]

No argument with either of you from me. EQ of any kind is bound to add phase distortion- even passive inline. The more EQ, the more phase is "messed with". That is why it's generally accepted that "less is more" if your aim is accurate reproduction of the input. As Chuck points out, this may or may not be the end goal and it comes down to a very simple and less analytical thing...........Does it sound good?

[Tahoebrian5]

I've made some progress on my bread board setup. After having to retrace my steps and start over a couple times u e finally got a setup that seems to work pretty well. I've mounted the terminal strips sideways so components can be mounted from above and opposing sides for screwdriver access. I've got them raised up a bit too to help with access. I'm thinking I will do another raised portion of breadboard for the pots and input jack. Trying to decide where to mount transformers. I think the PT will work nicely on the top right corner. If I follow standard practice I suppose the OT should be on the left. Also starting to contemplate how to handle grounding. I'm thinking about using another terminal strip as a star ground. Not sure if that will be ideal. Also thinking about just screwing in an actual star ground on the plywood where I need them.

I'm debating how safe this setup will be given that it does not have a metal chassis. Can anyone comment on this? It is my understanding that a metal chassis will help any possible electrocution return to ground quicker and lessen the risk of it going through any vital organs. I'm considering getting a piece of sheet metal or lead to cover the plywood. Thoughts?

[Tahoebrian5]

Ok, need some input on the layout. I've got the transformers set where I think they will work well. The OT is a bit close to the input circuit and gain / tone controls though. From what I understand it's desirable to keep the pt far from the input but what about the OT? Is there a problem with cross talk from the OT? Does it look too close? Another option I have is to cut my plastic strip I'm using for mounting pots in half and keep em all closer to the center. Thoughts?

[überfuzz]

Are you building a HiFi amplifier..? There is a proper way, or proper ways to do layouts... and then there's guitar amp layouts. My favourite amp, home-brew, has the OT less 15 cm from the input, and ridiculously close to the first (input) tube. If you ask me the thing to look out for is bad grounding schemes and local in/out on each tube.

[Tahoebrian5]

No hifi for me, just guitar.

[überfuzz]

I'd say you've got more than enough 'guitar amp distance' between the input stage and the OT. :-)

I've got an suggestion... Place the additional pre amp power supply RC filters in proximity to each pre amp stage. I've never done this myself, but it would be interesting to see how a proper star ground layout preforms compared to the ground layouts we normally see in guitar amps.

[Tahoebrian5]

I have been considering doing that. I just did another lap on Merlin's chapter on grounding and it makes a lot of sense. The dumble clone I built from ceriatone uses star grounds but they are connected to the chassis at multiple points. I'm considering going back through it and insulating the grounds from the chassis at all except one place. Merlin mentions near the input as the best place but Im thinking near the effects loop would be better for me. It seems most of the ground loop problems I encounter are due to effects.