Hey everyone,
I'm thinking of building some guitar pedals and making myself a fine pedalboard. As it wil be remaining mostly at home, and therefore not needing (or desire) to run the pedals on batteries, I'm also planning on building a linear power supply to feed them all.
First I was thinking of a simple, linear, regulated power supply, with a couple of amps to spare, using some 78** regs. One of these days, while looking into this, I've found some complaints about the noise and inteferance caused by gorund loops and so on. There, I decided to build an isolated psu with a small transformer for each pedal (something like a Spyder PSU). Altough a bit pricier (not obscene), it seemed like a quite good option. Yet, a few moments ago, I faced myself with this quesiton: altough all the power feeding into the pedals is isolated from one another, isn't the ground of the audio signal still connected to one another and, therefore, still making it just one big common gorund? As you might understand I'm quite a newbie in this fields, so parodn me my lack of knowledge.
Also, would a simple, single transformer, shared power supply cause that much noise?
My best regards,
JDias
I'm thinking of building some guitar pedals and making myself a fine pedalboard. As it wil be remaining mostly at home, and therefore not needing (or desire) to run the pedals on batteries, I'm also planning on building a linear power supply to feed them all.
First I was thinking of a simple, linear, regulated power supply, with a couple of amps to spare, using some 78** regs. One of these days, while looking into this, I've found some complaints about the noise and inteferance caused by gorund loops and so on. There, I decided to build an isolated psu with a small transformer for each pedal (something like a Spyder PSU). Altough a bit pricier (not obscene), it seemed like a quite good option. Yet, a few moments ago, I faced myself with this quesiton: altough all the power feeding into the pedals is isolated from one another, isn't the ground of the audio signal still connected to one another and, therefore, still making it just one big common gorund? As you might understand I'm quite a newbie in this fields, so parodn me my lack of knowledge.
Also, would a simple, single transformer, shared power supply cause that much noise?
My best regards,
JDias
I would be inclined to use one transformer and just daisy chain the supplies to each pedal.
The audio isn't high current so there shouldn't be any problem with ground loops.
Just make sure when you make the power supply there is no ground loop in that.
The charging impulses into the smoothing capacitors can cause havoc if it gets into the audio ground. Have the smoothing capacitors connected to rectifier on one side then the other side goes out to your regulator. Don't connect the rectifier side to the output or you will have serious problems.
The audio isn't high current so there shouldn't be any problem with ground loops.
Just make sure when you make the power supply there is no ground loop in that.
The charging impulses into the smoothing capacitors can cause havoc if it gets into the audio ground. Have the smoothing capacitors connected to rectifier on one side then the other side goes out to your regulator. Don't connect the rectifier side to the output or you will have serious problems.
Hum will be your biggest enemy if you attempt a whole pedalboard as DIY. I'd go for the isolated supply, and consider unconventional pedal construction that avoids ground loops hifi style. Commercial isolated pedalboard supplies didn't arise by magic, they serve a need.
Amplifiers amplify the difference between a signal connection and ground. Their output and DC supply also get referenced there, so as the signal is passed on, the other stages need that common reference. If one ground is not common with another, the difference can appear as noise. Ground loops are one way to make a ground no longer common.
Thank You for the answer,
Yes, I'm aware of the that phenomenon you are describing. I'll put togheter a simple schematic of the circuit I was initially idealizing just to check if I understood correctly what u ment.
Thanks again,
JDias
Thanks for your reply.
What do you mean by 'unconventional pedal construction that avoids ground loops'?
And do you believe that a transformer ( say like a small Myrra encapsulated) wiht it's own filtering and regulaiton for each pedal would be the way to go?
Also, in a single transformer - shared power configuration, would having a regulator for each pedal differ in any way form just a big chunky regulator for all?
Once again, thanks for the support.
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