Active, Passive, GNX4 Output - What to Use?

gtaus

Just got a new Behringer BX4500H bass amp head. It has both Active and Passive 1/4\" guitar inputs. I have both active and passive bass guitars. I have a couple of tech questions for you smart guys, if you can help.

On the BX4500H, there is a VU level meter. When I plug my active bass guitar into the jack, the VU meter needle barely moves off the scale, regardless of my gain and/or output dialed in. If I plug my active bass into the Passive jack, then I have all kinds of control over my gain and I can set the needle where ever I want. The owner's manual on the BX4500H amp states that the Active jack is -10 dB for \"high output active\" instruments. I thought \"active\" was \"active\", but now I wonder if there are \"active\" instruments (like my active bass guitar) and also there are \"high output active\" instruments that my bass guitar seems not to be? How do you measure the output of an active bass guitar to determine if it falls into the \"high output active\" class, or not?

Second question, if you plug an active bass guitar into the GNX4, and send the GNX4 1/4\" output to the head amp, do you use the active or passive jack on the head amp? Or does it matter how much output you dial in the level knob on the back on the GNX4? If you use the GNX4, does it matter if you have either an active or passive bass guitar, or does the GNX4 1/4\" output remain constant?

Well, sorry for all the questions. Just got new gear and now have new issues to consider in my setup. I know I could plug and play and just try out everything, but I'm more concerned about any technical reasons why there might be a correct setup and/or why a wrong setup might damage the gear. Any help appreciated.

iliace

You can have the pickup rewired to output louder. Or maybe a problem with your battery?

In terms of input into GNX, the fact that it's active will only affect the GNX output insofar as it affects whatever processing the GNX does. For the most part, I would think it only affects the tone. Just watch the clip light on the GNX.

I doubt it matters much whether you plug into the active or passive input from the GNX, but my guess would be that if the bass is active, the input should also be active.

gtaus

Just put a new battery in my active bass. So I know that is not the issue. The specs on the head amp state that the Active input is -10 dB lower than the Passive input. I think that attenuation at the source is probably more than I would have thought. And to make things more confusing, the Behringer manual states that the Active input is for high output active instruments. Don't know if something is getting lost in the translation from German or what.

Are there different levels of output on active guitars? I thought the whole deal with active guitars is that they had one standard output level. That doesn't seem to be true.

iliace

Yeah, dude. I don't know specifically how it's done, but you can wire the pickup to be louder, both passive and active. I have a guitar with active pickups, and I know there's a gain control that I can change if I opened it up and bothered to look for it - to make the active up to 6dB louder.

gtaus

Thanks, I did not know active pickups had different output levels. So I guess there is a difference between active and high output active bass guitars. The amp head manual made it sound like you could use the Passive input for both passive and active bass guitars, but that you would want to use the Passive input if your guitar had the high output active pickups.

FWIW, my active bass guitar works just fine on the Passive input of the head amp. I have lots of control on the gain and can dial in just about any level on the VU meter. Evidently, my active guitar must be a lower output active bass because when jacked into the Active input on the head amp, the needle barely comes off the scale. It still sounds good, and loud, but the needle itself does not hardly move.