Line out woes

mcdeans · #1 06-09-2011, 10:37 PM

I'm fairly new to bass and live sound, so I need some help from any experts out there.

I've got an Acoustic B200H plus 4x10 and 1x15 cabinets, which sounds pretty good. However, when I connect it to my Behringer mini-mixer from the XLR line out on the back, I don't get any signal unless the main volume is turned up. And the louder the main volume, the louder the line out feed. I would have thought that the XLR line out would operate independently of the main volume. In fact there is a line out level next to the XLR connector.

Indeed, I have a Fender Bassman 400 on loan to compare against, and it has the XLR line out and the main volume control operating independently. So I can turn the main volume all the way down, and just use headphones plugged into the mixer. (That way I can practice without bugging the family, just in case you were wondering why I'd want to do this.)

So, is the Acoustic operating incorrectly, or is that just the way it works? What about other makes, how do they handle line out/main volume?

Many thanks for any help/advice.

uhdinator · #2 06-10-2011, 08:12 AM

Line out is fed from the pre amp / gain knob. Not master volume.

You set the gain and leave it. Then adjust volume of the amp with the master vol.

If you are recording and want the amp vol low or off it will still send line out with pre / gain on.

Konigstiger22 · #3 06-10-2011, 08:21 AM

I have the same B200h setup and usually plug directly into the board at gigs using the xlr in the back. I then run my master pretty low as it usually is just a monitor. Sound guy has never complained that he wasn't getting a loud enough signal. I would check and make sure the xlr volume knob is turned up and if that doesn't work, maybe take it back and exchange it for another one.

mcdeans · #4 06-10-2011, 09:50 AM

Thanks for your responses guys.

I have been using the XLR output knob to adjust, and it does indeed control the XLR out volume, but only within the range set by the master volume knob. If the master volume is turned all the way down, then there is no audible output from the XLR.

Yeah, I'm thinking that this system is faulty, and I'll have to get it switched.

mcdeans · #5 06-10-2011, 11:34 AM

Further thoughts.

I've been looking at the signal flow diagrams in the manual (http://acousticamplification.com/pro...00H-Manual.pdf). I'm no electronics expert, but it seems clear that the signal goes through the pre-amp, equalizer, and master volume control before going to the XLR out area. (It doesn't help that the volume is mislabeled as a second preamp gain, but check the diagram for the B600H - almost identical, but labeled differently.)

So, the XLR out level being controlled by the master volume appears to be by design. Bugger.

TimmyP · #6 06-11-2011, 02:04 AM

IMHO, On a properly designed amp, the DI out should also be unaffected by the tone controls (or should be selectable). The EQ that works for your cabinet likely won't be anywhere near optimal for the PA (if, for no other reason, because your cabinet and the PA sound nothing alike).