Let's get real - How good is good enough?

[StarTrucker]

I see the average GDIY'er on this forum as falling under two categories :

1. The professional engineer or hobbiest looking to DIY the tools they use to make their records. Diy enthusiasts who are interested because they want the sounds they hear on other records or in their head that they want to put on tape.

2. The electronics guru who may or may not be a musician or engineer/producer. These people really know their hardcore theory and graciously share with us as part of the community. Career engineers and techs.

Of course there is overlap and that's why we all share so much.

In terms of design, how good is good enough for the regular guy (1. above)? Someone in a thread mentioned dialing in a regulated power supply for tube preamps. He suggested considering power transformer impedance and lots of technical data-sheet level details. Are these kinds of details from the pros over the top for average builders who need reliable studio grade equipment? Where is the line between optimal performance and day to day usability for a professional record.

Ex. A 3 or 4 stage RC PSU filter section and a bleeder resistor is "regulated" and common in lots of classic gear. When does it become unnecessary to include more high tech and complicated designs? Are the old ways good enough to get by on any major record?

 

[ruffrecords]

Ex. A 3 or 4 stage RC PSU filter section and a bleeder resistor is "regulated" and common in lots of classic gear. When does it become unnecessary to include more high tech and complicated designs? Are the old ways good enough to get by on any major record?

As usual, the answer is it depends but in simple terms the answer is when it is class A. In a class A system, the total power consumption is fixed and, with adequate decoupling, this means the supply current is pretty much constant. It does not matter what the signal level is, the total power drawn is always the same. Essentially class A circuits divert current from and active device to and from a load. This means you can get away with a multiple stage RC smoothing circuit and still be confident of the operating conditions of the circuit.

As soon as you move to class AB or B (99% of all op amps and most guitar amps), the total power consumption is directly related to signal level. With no signal, the current draw can be quite small but the bigger the signal the bigger the current draw. This means the output of a multiple stage RC smoothing circuit will drop as the output signal increases. This results in the well known "sag" in class B guitar amps. For pro gear sag is not acceptable so you need a regulated power supply to ensure the operating conditions of the circuit do not alter with signal level (unless you want them to of course).

Cheers

Ian