Amp head, passive cab, powered pa cab

[jezzaboy]

Just pondering, as you do. 

 

Scenario 1

 

So I plug my amp head into a normal bass cab via the speakon connections.

 

If I take a cable from the send socket on the amp into the powered pa cab, would this allow me to send the amp signal into the active pa cab and let me use the amps eq section? In other words, if I turn up the bass on the amp, would this alter the sound going into the active speaker?

 

Scenario 2

 

Or keep the normal bass cab plugged in as above but use the amp`s di to send a post signal into the active speaker?

 

 

I hasten to add I haven`t done this and might never do it as it might be daft / sound crap / blow up me or the kit. Too much time on my hands at the moment!

 

 

[Bill Fitzmaurice]

Functionally a send and an active DI should be essentially the same. They may differ in whether they're pre or post EQ. The amp block diagram would reveal that. 

[Phil Starr]

Is there any reason you can't just try it?

 

The only issue is signal levels and that is a function of which model of PA cab and which bass amp. Nearly all active PA speakers will take a mic level and a line level signal. Your DI out could be either or both depending upon your bass amp. Not all 'line' levels are the same. However you have volume controls which should let you balance the two 9 times out of 10.

 

Turn the PA speaker right down and run an XLR from the DI out switched to post to the mic input. If the volume is at zero you aren't going to get any sound so nothing can go wrong. If you are really worried switch the gain on the PA speaker to 'line'. Turn the volume on the PA up really slowly and something should come out of the speaker. If you can't get it loud enough but the sound is good then you just need more gain. Switching the PA from line to mic will give a lot more gain so turn the volume right down before you try that. Or you can try turning down and switching the DI out from mic to line and trying again. Somewhere you should be able to get a match where the whole volume range is available to you. So long as you always turn the volumes right down before each change you can't really go wrong

 

The only problem with the send is that in a few amps plugging into the send disconnects the bass amp from the pre-amp. Again that depends upon exactly which model you have. Sends are generally line level but may be a slightly lower line level.

[DGBass]

Jezz, if its your Ashdown MAG you are trying to do this with into a powered sub, there is likely two ways to do it.

1. Take a standard guitar lead and connect it to the tuner/line out on the amp and on the sub find the unbalanced line in socket( if it has one). Turn the levels right down while doing this then gradually increase the levels both ends. The tuner/line out is a fairly hot signal so don't over do the pre-amp volume or it might clip/distort the subs input. Gradually increase until you get the required levels from the sub.

2. The DI out on MAG's are as follows:  600 Ohms balanced, level -20dBu nominal. You need a balanced XLR cable to do this and plug it into the Mag then find the DI INPUT on the sub. Dont use an unbalanced XLR cable.  It might even say on the sub whether it takes balanced or unbalanced. On your MAG the DI is POST pre-amp so is affected by the input volume and tone controls on the amp. Again turn the levels up both ends gradually until you detect output from the sub. Most subs will have the input socket labelled 'input balanced' or 'input unbalanced'.

    

[fretmeister]

The active PA cab won't sound the same as your regular cab. the PA cab will be designed to be as close to FRFR as possible as PA cabs are, and the bass cab will be far more of a sound shaping device.

 

I'd expect to EQ the PA cab very differently to the regular bass cab.

 

If that is an issue for you.

[jezzaboy]

Thanks for the replies.

 

I already tried it out and it does work but being in a flat, I can`t give it loads of welly to see how it sounds. It was s a bit of faffing about requiring a Digbeth pre amp, a mic pre amp, bass amp, bass cab, pa cab and lots of cables. Good for killing a couple of hours and no blue smoke which is always a bonus!

 

Too much hassle so I will be popping over to Fife to meet up with DGBass to sort something out.