Need help with crossover for subwoofer, amp

[tim_7string]

We currently use the following for bar gigs:

 

Yamaha EMX512SC 8/12 channel powered mixer (power used only for monitors)

Samson MIXPAD9 6/9 channel mixer (occasional use, not every gig)

Yamaha S115V Mains (2)

Yamaha SM12V Floor Monitors (2)

Yamaha SW118V Subwoofer

QSC GX-3 Power amp (used for one subwoofer and 2 mains daisy-chained)

 

I'd like to get another SW118V subwoofer and another QSC amp in time for some larger gigs this summer. However, I've only been using the built-in crossover in the GX-3 for now. I've never used a passive or active crossover with my own PA equipment before.

 

What would be the best kind to get for this setup? Also, would it be better to get a GX-5 for the subs and use the current GX-3 for the mains only?

 

Any help or comments are appreciated. Thanks.

[agedhorse]

You are using an active crossover with your system right now. That's what's built into your GX-3.

 

That's just about the right power for your subs, the GX-5 is ok but a little high IMO.

 

Are you hitting the limit LEDs on the amp much or at all?

 

You are using the GX-3 in biamp mode right? Read the manual to verify before answering here please, no need to go down the road of using incorrect terminology. YOu might post a drawing of exactly how you have things set up too.

[tim_7string]

You probably don't recall, but it was you that originally suggested the QSC GX-3 for me a year ago due to the crossover built into the amp. Thanks for that, by the way.

 

I use it with Channel 1 going to the subwoofer, Channel 2 going to the main speakers. If that is considered biamp, then yes, it is biamp.

 

So, another GX-3 would be preferable instead of the GX-5? I definitely don't want to damage anything.

 

And no, we never hit the limit LEDs on the amp. I set the EMX512SC mixer to about 25-30% main output. I have the GX-3 power amp knobs set about 80%. Not sure if that is too high or not, but I haven't had any problems in the past year. I have never set the knobs to 100%.

[Pro Sound Guy]

 

You probably don't recall, but it was you that originally suggested the QSC GX-3 for me a year ago due to the crossover built into the amp. Thanks for that, by the way. I use it with Channel 1 going to the subwoofer, Channel 2 going to the main speakers. If that is considered biamp, then yes, it is biamp. So, another GX-3 would be preferable instead of the GX-5? I definitely don't want to damage anything. And no, we never hit the limit LEDs on the amp. I set the EMX512SC mixer to about 25-30% main output. I have the GX-3 power amp knobs set about 80%. Not sure if that is too high or not, but I haven't had any problems in the past year. I have never set the knobs to 100%.

Get your gain structure right. There is plenty of information on how to get it right. Here is a start for you.

 

http://www.rane.com/note135.html

[agedhorse]

 

You probably don't recall, but it was you that originally suggested the QSC GX-3 for me a year ago due to the crossover built into the amp. Thanks for that, by the way. I use it with Channel 1 going to the subwoofer, Channel 2 going to the main speakers. If that is considered biamp, then yes, it is biamp. So, another GX-3 would be preferable instead of the GX-5? I definitely don't want to damage anything.

 

 

Good, I think the GX-3 is properly sized for your application.

[tim_7string]

Good to know, thanks.

 

I was thinking of mirroring each side of the PA like I am now, but with only one speaker per output instead of the daisy-chained mains. This way, I'd use the built-in crossovers within each GX-3:

 

Left Main Out of mixer

QSC GX-3 Ch 1 ---> Left subwoofer

QSC GX-3 Ch 2 ---> Left Main

 

Right Main Out of mixer

QSC GX-3 Ch 1 ---> Right subwoofer

QSC GX-3 Ch 2 ---> Right Main

 

Would this cause any problems (like phasing or delays)? Or would it be better to have a separate active crossover, using one amp for subwoofers only, the other for mains only?

[nchangin]

 

Good to know, thanks. I was thinking of mirroring each side of the PA like I am now, but with only one speaker per output instead of the daisy-chained mains. This way, I'd use the built-in crossovers within each GX-3: Left Main Out of mixer QSC GX-3 Ch 1 ---> Left subwoofer QSC GX-3 Ch 2 ---> Left Main Right Main Out of mixer QSC GX-3 Ch 1 ---> Right subwoofer QSC GX-3 Ch 2 ---> Right Main Would this cause any problems (like phasing or delays)? Or would it be better to have a separate active crossover, using one amp for subwoofers only, the other for mains only?

 

 

Two amps would be a viable option OR You could pararell subs for 4 ohm load off ch 1 would be 425 WPC into 4 ohm vs 300 WPC into 8 ohms. Also could parallel mains for 4 ohm load for 425 WPC vs 300 WPC into 8 ohms. If you don't want to daisy chain go for 2 amps, with two amps means more power draw. According to manual: 8 + 8 ohm load current draw 9.75 A (Full power is breaker limited to short periods.)

 

Personal opinion: I like headroom with spare clean wattage so amps can run stable and not close their thresh hold. GX 5 better option as you don't have to run it as hard, but as always if you overdrive, snap crackle pop. From what I've researched those 18" need juice to get them purring.

 

See this review: This subwoofer is great. We run ours with a 1200 watt RMS amp. You will need alot of power. 600 watts as recommended will not suffice. The only problem...although it is not the subs fault...you need two of these subs for a large room. one sub adds the essence of bass but no true punch. our synth sounds great coming out of this but from 50 yards away the kick drum is present but not aggresive sounding. even when we used a yamaha subkick. two of these would double the sound output and give you the punch you are looking for. of course you will need 2400 watts to truly make it sound good. (http://www.musiciansfriend.com/pro-audio/yamaha-sw118v-club-series-v-subwoofer)

 

Subjective and opinions may vary.

 

Ask yourself does it do what you need it to do or is it weak? Hence adding the sub?

[nchangin]

Also the post applies only if you are ok with MONO (assuming your in a band and don't need stereo)

[agedhorse]

 

Personal opinion: I like headroom with spare clean wattage so amps can run stable and not close their thresh hold. GX 5 better option as you don't have to run it as hard, but as always if you overdrive, snap crackle pop. From what I've researched those 18" need juice to get them purring. See this review: This subwoofer is great. We run ours with a 1200 watt RMS amp. You will need alot of power. 600 watts as recommended will not suffice. The only problem...although it is not the subs fault...you need two of these subs for a large room. one sub adds the essence of bass but no true punch. our synth sounds great coming out of this but from 50 yards away the kick drum is present but not aggresive sounding. even when we used a yamaha subkick. two of these would double the sound output and give you the punch you are looking for. of course you will need 2400 watts to truly make it sound good. ( http://www.musiciansfriend.com/pro-audio/yamaha-sw118v-club-series-v-subwoofer ) Subjective and opinions may vary.

 

 

Obviously you have never worked in a recone shop or been responsable for warranty claims on speaker products.

[Unalaska]

No the speaker does not need more "juice". 2 Options: add a sub to the exsisting amp setup or add another sub and GX3. 1 will drive the left stack, 1 drives the right stack. Easy, no issues.

 

I'd opt for another gx3: 425/2= 212.5w vs 300w per driver. So yeah, I'd add another amp. This would work well for your situation and not be too hard at all to setup.

 

Another option (what I'd personally do) is use a DBX223 crossover w/ the 40hz HPF, GX3 for tops, GX5 for subs. That's just me, that's what I'd do.

[tim_7string]

I'd like to keep it a somewhat simple and reliable (i.e. won't blow stuff up) setup. Using the GX-3's built-in crossovers seems like a simpler way to go at this point for me, so I'll probably just go that route of adding another Yamaha sub and another QSC GX-3.

 

Thanks for the input, guys.

[gonzobassman]

Another option (what I'd personally do) is use a DBX223 crossover w/ the 40hz HPF, GX3 for tops, GX5 for subs. That's just me, that's what I'd do.

 

This is exactly what I DO!!! Same exact set-up except I have a couple of PV single 18s.They probably aren't as good as the Yamaha 18s that you have.Maybe its just me,but this system sounds cleaner using the external crossover (DBX223 w/40hz HPF engadged),than running the amps in"crossover"mode.The crossover is fairly simple,and once set rarely needs adjustment.With that I also run one more GX-3 for two seperate monitor mixes.Usually one wedge per side. I call this my "little system",and it works well.Its no PRX,or SRX,but it gets the job done,and I usually get complimented on the sound,as well as the fact that the volume is at a good level for smaller venues.

[RoadRanger]

Using a GX5 on either the PV118's or Yammy club subs is kinda pushing your luck with 500w into 300w rated drivers - but I too have one system I run with a GX5 into PV118's and I'm not particularly worried about it. I know of folks running a bridged RMX2450 into their's like that review above recommended - 1200w into each driver . At 500w you don't have to worry about overexcursion as long as you run a proper HPF - the DBX223 has one but the GX5 doesn't . If you want to just use the internal crossovers of the GX series you should really stick with the GX3 on subs...

[agedhorse]

I have a pile of customer Yamaha baskets in the shop right now for recones... not enough rig and too much power for the gig. I'm down to my last few 18" kits... they didn't last long as there was a run on "stupid" this year already.

[RoadRanger]

I have a pile of customer Yamaha baskets in the shop right now for recones... not enough rig and too much power for the gig. I'm down to my last few 18" kits... they didn't last long as there was a run on "stupid" this year already.

Yah, I just sold my two RMX2450's to somebody who's gonna bridge them into some old subs . Well, after he blows that {censored} up he won't be a potential competitor anymore .

[agedhorse]

Yah, I just sold my two RMX2450's to somebody who's gonna bridge them into some old subs . Well, after he blows that {censored} up he won't be a potential competitor anymore .

 

That is one way to kill the competition and make them feel good about getting killed too