string tension.
 

do the types of strings affect the tension on strings? like do round wound have a lower string tension then flats? or half flats? the guy i bring my bass to get set up to said it might. i made the switch from rounds to half flats thats why he brought it up.

It's more complicated than that. You really have to ask about specific string sets, rather than getting an easy answer like "flats have more tension".

Gauge, material, core, number of windings... there are many factors that affect tension. For example, DR Lo Riders and Hi Beams. Bothe stainless steel roundwounds from the same company. But the Lo Riders have a hex core compared to the Hi Beams' round core and have a greater tension, or at least feel that way.

Some publsih tension charts, e.g. Circle K and Daddario. Take a look at Daddario's charts in particular to see the difference in tension between different gauges of the same type of string, then the same gauge across different types (flats, steel round, nickel round, half-round etc). And

Tension != Stiffness. Given same materials used, and same gauge, the round core will have more tension than the hex core but it will not be as stiff.

Thanks, you're totally correct - my lack of clarity. I put that qualifier about 'feel' in there because I wasn't sure what the comparative tension of the strings is but know that the hex core will feel stiffer and some people might equate that with higher tension.

I can confirm from experience that, comapring between my two 34" scale basses, the .102 Circle K with 40.4lbs of tension feels looser than the Daddario ProSteel with 34.4lbs. Higher tension definitely does not equal stiffer feel.

Many people here use "tension" to mean perceived tension or perceived stiffness or feel, but the actual scientific definition is the pull force exerted on the bridge or headstock, which is dependant only on scale, pitch and "unit weight" = the mass of one inch of string. Because some strings are denser than others (flats) their mass is higher for the same gauge, therefore higher scientific tension.

The first few pages of the D'Addario tension chart explains all, essential reading http://www.daddario.com/upload/tension_chart_13934.pdf