I always recommend use of a regulator for exactly the reasons that Buzz and Thomas indicate.

Im far from an expert... but from my meager research, & understanding of the concept-

With a venturi style burner- the air is more or less regulated/dictated by the flow of the gas through it. It can be, and is adjusted a bit more more by a choke plate. But, the air is pulled in and dependant on fuel flow.

I run a forced air burner setup. My build thread is here- 

With a forced air setup- your fuel and air are separately introduced, and regulated. You control airflow by either controlling the blower speed, or by physically blocking/redirecting the air. The fuel pressure is only controlled by a regulator. Flow can then be metered or shut off by a valve.

A venturi burner mixes the fuel and air together right at the tube and burner. It requires higher gas pressure/flow to pull the air. From what I've read, 10-20 psi can be normal.

With a farb- you're more remotely dumping gas into a pipe, and the airflow mixes it and moves it to the burner "chamber". You wind up running at lower fuel pressure requirements than a vent. burner. My burner seems to like 4-5 psi on my gauge.

These are the reasons I went forced air over venturi burner. It was more complicated build than a farb, as a former plumber I had some things on hand, and I learned ALOT from folks here in the process.

Either way, a fuel pressure regulator is a very necessary component. I use one, and a ball shut off valve at my forge just for safety. A needle valve is not as necessary, just a much nicer means of additional fuel control at the forge with forced air.