Agree with Manistory.
You need to test with DMM to check a correctess of your DIY otherwise if you just turn it on, you'll have a large possibility to burn something in the circuit board especially with tube equipment. Also it's good to know what is Votage V, Current I, Resistance R, Impedance Z, Reactance X, Inductance L, Capacitance C, Freequency W, Power P, Measurements units of above listed.
Start with cheap equipment first to practice soldering, measurements (I to actually feel that you're not ready to DIY mod your preamp and practicing on cheap equipment will actually give you a cursory look to estimate yourself) etc and than exersize your DIY when you feel ready to take a risk.
Also having a camera to picture 'before' scenario would be very helpful in any tech DIY projects. I use Nikon D3000/Nikkor 18 - 55mm lens.
Disclosure: I'm part-time studio tech/full time software engineer.
You need to test with DMM to check a correctess of your DIY otherwise if you just turn it on, you'll have a large possibility to burn something in the circuit board especially with tube equipment. Also it's good to know what is Votage V, Current I, Resistance R, Impedance Z, Reactance X, Inductance L, Capacitance C, Freequency W, Power P, Measurements units of above listed.
Start with cheap equipment first to practice soldering, measurements (I to actually feel that you're not ready to DIY mod your preamp and practicing on cheap equipment will actually give you a cursory look to estimate yourself) etc and than exersize your DIY when you feel ready to take a risk.
Also having a camera to picture 'before' scenario would be very helpful in any tech DIY projects. I use Nikon D3000/Nikkor 18 - 55mm lens.
Disclosure: I'm part-time studio tech/full time software engineer.