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Moving from Passive FOH/Sub to Active FOH/Passive Sub

lhrocker

Member
Messages
116
Our band started gigging regularly last year and it looks like this year will be even busier. We're a 5 piece that usually plays indoors with passive speakers and powered mixers, that is supplied by the singer. I think this year, we may start using my rig, with is an XR18 mixer with powered Alto TS212's.

I also have older passive speakers and subs and I'm thinking of using these for monitors/subs with a power amp. Cabling from the mixer to amp to speakers wouldn't be a problem and it would be a single power cable to the power amp (one side for sub and one side for monitors) rather than a power cable for each additional sub/monitor.

Is the expense of going all powered worth it and what does make a difference in sound?
 

335guy

Member
Messages
5,229
Potential issues when blending powered and passive speakers.

1) You need an electronic crossover for those passive sub/s. Not sure if the XR18 has one but I don't think so. The amp you plan on using MAY have one, as some do. However, since the XR18 only has two main outs, you'll probably want to run cabling from those outs to both of the Alto's. I'd recommend a quality electronic crossover after the mixer's out. Then run the highs to the Alto's and the lows to the amp for the subs. Since the Alto's do not have a high pass filter, they need to have the signal from the mixer "crossed over" 1st if using subs.
2) Does that amp have enough power to run two subs off of one channel? Subs require a lot of power. Even a lowly rated 300 watt sub should see 450 watts minimum, and preferably more. And do the subs ohms match up? If the subs are 4 ohms ea. and you use two per channel, that will cause a problem for some amps.
3) Even if your amp does have a crossover, it still won't help the Alto's because they have no high pass filtering.

Is the expense of going all powered worth it and what does make a difference in sound?
Depends, but for many, it is worth it. The little bit of extra power cabling and hook up time is minimal. It's more convenient in the sense that the power amp and crossover is built inside the subs ( in the case of the Alto TSSUB 18 ), so no need for external power amps and crossovers. One simply run XLR cable from the mixer to the sub/s, then run a XLR cable from the high passed out to the Alto TS212. You can look into aux feeding the subs, which some like/prefer, as an alternate way of running subs from your mixer. But you still need a crossover when using passive subs, and with those Alto's.

As to whether the sound is better, that is dependent on which speakers one is using. For most novices, when using matched components, it will be easier, simpler and usually sound better running active speakers.
 

lhrocker

Member
Messages
116
Thanx for the quick response.

1/3. For the sub, I'm taking one of the 6 Aux's with a Low Pass so no separate crossover is needed.
2. I have a Crown 2500XL and the subs are 8 ohm each. It should be fine.

Maybe I will move towards the powered subs. Still deciding.

Thanx - Pete
 

335guy

Member
Messages
5,229
1/3. For the sub, I'm taking one of the 6 Aux's with a Low Pass so no separate crossover is needed.
So the XR18 has a good low pass filter for subs then? And what about the Alto mains? Will you be high passing them at the same freq. as the subs?


I have a Crown 2500XL and the subs are 8 ohm each. It should be fine.
That's a good amp. Yeah, if your subs are 8 ohms, then that Crown should drive them okay. You'll be getting 775 watts per channel divided by 2 =388 watts per sub. Almost too bad your subs weren't 4 ohms ea, because that amp is stable to a 2 ohm load and then each sub would get 600 watts.
 

lhrocker

Member
Messages
116
So the XR18 has a good low pass filter for subs then? And what about the Alto mains? Will you be high passing them at the same freq. as the subs?

I don't I would need to but I could. Would I need to If I low passed the subs at around 120?
 

sants

Member
Messages
2,415
I have found switching to powered speakers is nice especially if you are playing small places and providing your own pa.

The efficiency and lower power draw alone is worth it IMO.
 

Floyd Eye

Senior Member
Messages
13,838
What older passive speakers do you have? They may be better for tops than the Altos. I have a gaggle of Alto TS112As. I only use them for monitors.

Are the LPFs on the XR18 fixed or adjustable? What passive subs do you have?
 

lhrocker

Member
Messages
116
What older passive speakers do you have? They may be better for tops than the Altos. I have a gaggle of Alto TS112As. I only use them for monitors.

Are the LPFs on the XR18 fixed or adjustable? What passive subs do you have?
Peavey SP2's. Big and Bulky. The LPF's are adjustable on the XR18.
 






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