PRO AMP INPUT types ??

[Scott L]

Greetings all,

I am considering the purchase of a PRO style amp to drive my subwoofer section, but am a bit unclear as to how the various input types compare.

Will a 1/4" "balanced" input be compatible with the normal audio output from an electronic crossover? I mean, I already have cables with a 1/4"(to amp) on one end and phono (from X-over) on the other end, but, am not sure where "balanced" vs. "unbalanced" comes in. I think the term TRS comes into this equation as well ? Thanks.

[billfitzmaurice]

TRS is 2 conductor plus ground, just like XLR. Pro-sound crossovers typically use XLR, but some have TRS as well. If your crossover does not have XLR or TRS it's not pro-grade.

[Hackomatic]

If your crossover is using RCA "phono" plugs on the output, it is an unbalanced output. That shouldn't be a problem since you can run an unbalanced output into the amp's balanced input via the 1/4" jack. Hopefully it is NOT a 1/4" TRS plug (TRS stands for Tip, Ring, Sleeve and is characterized by 3 separate sections on the 1/4" plug).

If your cables are RCA out on the crossover end and TS on the other end (only Tip and Sleeve characterized by only 2 separate conductors) then you will be just fine. The tip will be the Hi or Hot feed on the amp and the sleeve will tie the amp's low side and shield together, which is what you want in this case.

If your cable's 1/4" connectors ARE TRS, then you will need to get a cable that is just TS on the 1/4" end to work correctly.

Many amps though have either balanced 1/4" or XLR AND RCA unbalanced inputs

HTH

[Scott L]

After further research, I have found:

The cables are phono to T/S.

I found a pdf of the back of said amp, and it shows a schematic of the 1/4 " input as a T/R/S input. If the cable end puts the shield and the negative together (like I believe you said) will I be okay ?

[Hackomatic]

Affirmative!

[dotzs]

The thing about balanced cords is that they can run for long lengths and a 2 conductor input output will make noise over about 15 feet--like a guitar cord.

[billfitzmaurice]

The thing about balanced cords is that they can run for long lengths and a 2 conductor input output will make noise over about 15 feet--like a guitar cord.

What actually occurs is that unbalanced connections are highly susceptible to ground loops, and the longer the interconnect and the AC lines the higher the gound loop noise level. Properly engineered devices all using balanced lines are immune to ground looping.