Designing Studio Gear

[lukegalea16]

Hi, I am used to building guitar pedals but want to start building studio gear. In particular I want to start with building a One Knob Gain/EQ Control as an outboard gear which can accept a line input and returns a line output. The signal would be coming in from a line level instrument or sound card and back into the sound card input. My experience with guitar pedals using them as outboard gear indicates that in some cases a reamp box with an isolating transformer is needed before the input because of ground loops which result in noise. Thus my question is: When building outboard gear such as my mentioned idea, is an in-built reamp box required to be added at the input or what is the process usually? Since I mentioned my concern with noise I fear that leaving the input without any form of 'reamping' will cause ground noise.

[dangus]

Most stuff I've looked into doesn't have transformers; they cost a lot to do right. If you're doing live stuff in venues with dodgy wiring and multiple grounds, it would be good to have something in your box of tricks to provide full isolation, not just an extension cord with the ground pin lopped off.

[bansuri]

you need balanced connections very easy to implement:
at input added a differential amplifier with 0dB gain, connected to a 3-pole Jack
the output even easier just another identical output resistor from gnd to the middle pole.
You can use even normal 2-pole jacks, but loosing the gnd compensation.
The sound card should have balanced inputs too (you said Studio)

[dotneck335]

Rod Elliott explains balanced transmitters and receivers:

Balanced Line Driver & Receiver
Balanced Transmitter and Receiver II
Balanced I/O

[leadbelly]

You don't need to replicate a reamp box and you don't need balanced connections. You may need to deal with ground loops. A transformer is the gold plated solution and is common with studio equipment. You may be able to get by with careful attention to how you do your power and signal cabling and circuit grounding. Ground loop breakers using diodes, resistors, and caps are much cheaper than transformers.