Live Sound & Production

[lonotes]

I've been working in a club recently that has a pair of Ramsdell Audio 660R subs (http://www.ramsdellproaudio.com/products/subs/660r.htm). The rest of the system is mine, consisting of JBL MRX512m's for tops and monitors (drum monitor is a JBL VRX915). Currently I'm powering the monitors with a pair of QSC PLX 1602's, one cab per side. The subs are running off of a PLX 2402, also one cab per side. The tops run off of a PLX 3002. I also have an additional 2402 that is currently unused. This configuration is plenty loud and clear for the FOH. My concern is that the monitors may be a bit on the weak side before feedback sets in. I have to crank them pretty hard sometimes to be heard clearly. What I'm considering is rearranging things so that the monitors run off of the pair of 2402's, and the subs run off of the 1602's in bridged mono one cab per amp. This would bump my available power from 300 to 425 watts/channel on the monitors at 8 ohms. It would also bump the subs from 800 to 1600 wpc at 4 ohms. Would this give me any benefit regarding increased monitor volume at lower gain, thereby reducing feedback? Or would there not be enough difference to be worth the trouble? Or am I just inviting calamity?

[abzurd]

I'm not following the feedback issue with the monitors and how it relates to the amps. If you're getting feedback now that's telling you you've reached the limit of practical volume on stage. You either turn down or eq the feedback out. A larger amp won't help. If anything it will hurt as you'll now be able to get louder which will mean more potential for feedback.

[RoadRanger]

[Tomm Williams]

As already stated, amp power is not the issue. You need to work with mic selection and monitor placement. Also, are you running compression or FX through the monitors? it will cause problems if you do.

[abzurd]

I just looked up the power ratings for the monitors and subs and it does seemingly make more sense to switch up the amps to what you're proposing. It takes you to the RMS rating of the subs and just a touch over the RMS on the monitors. That's perfectly fine and more appropriate, IMO. It should help headroom on the subs as you're only at half the RMS rating currently.

[lonotes]

So far, the consensus seems to be that I'm crazy. That's why I asked before I started reconfiguring things.

[RoadRanger]

abzurd wrote:
It should help headroom on the subs as you're only at half the RMS rating currently.

"Headroom" is power you never use - why would anyone want more of it  ?

[lonotes]

So I'm not crazy?

[RoadRanger]

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lonotes wrote:

So I'm not crazy?

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The "fun" thing about this forum is you can always find someone willing to tell you what you want to hear  .

[abzurd]

Not crazy in that reconfiguring the amps makes sense, just not for the reason stated.

[abzurd]

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RoadRanger wrote:

abzurd wrote:
It should help headroom on the subs as you're only at half the RMS rating currently.

"Headroom" is power you never use - why would anyone want more of it  ?

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I'm assuming you're joking.

[lonotes]

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RoadRanger wrote:

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lonotes wrote:

So I'm not crazy?

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The "fun" thing about this forum is you can always find someone willing to tell you what you want to hear  .

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The "voices" already do that for me. I know they're not real, but sometimes they have some good ideas.

[RoadRanger]

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abzurd wrote:

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RoadRanger wrote:

abzurd wrote:
It should help headroom on the subs as you're only at half the RMS rating currently.

"Headroom" is power you never use - why would anyone want more of it  ?

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I'm assuming you're joking.

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No, I'm not.

[abzurd]

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RoadRanger wrote:

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abzurd wrote:

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RoadRanger wrote:

abzurd wrote:
It should help headroom on the subs as you're only at half the RMS rating currently.

"Headroom" is power you never use - why would anyone want more of it  ?

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I'm assuming you're joking.

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No, I'm not.

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OK then. Headroom is stupid. Even if it's free. Got it. Stupid headroom.

[RoadRanger]

OTOH if you will be playing bigger venues where you need more SPL it would make sense to "power up" your stuff. If it is plenty loud now why bother? In any case your issue is monitor feedback so that's worth "fixing" first . My favorite method is lowering stage volume . IME if you are using more than 75 watts per monitor you'll need earplugs on-stage for sure .

[dboomer]

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lonotes wrote:

Would this give me any benefit regarding increased monitor volume at lower gain, thereby reducing feedback? 

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If you end up with the same level you'll end up with the same gain ... so no difference.

Unless ......

The only time you will benefit from lower feedback because of a bigger power amp is if you are increasing the gain of a smaller amp because it is not loud enough that would not be necessary with a bigger amp.

Feedback happens because of "gain" but not because of "power".  But if you were comparing say a puny system  to a system that had enormous what could end up happening is that you may continue to boost the gain on the smaller system even into  clipping in order to get enough level.    The loud parts wouldn't get any louder at this point but if you continue to increase the gain the quieter parts will (average level).  This increased gain will cause feedback sooner.

With the small difference you are describing I doubt it's worth it.

[lonotes]

Thank you all for your responses. That's why I love this place.

[oldschooler]

Sometimes i wonder where he comes up with this stuff. Contradicts his statements in message 15, then gives a max 75 watts power rating for monitors.

I'm starting to think the best answer on the forum is, It depends.

[RoadRanger]

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oldschooler wrote:
Sometimes i wonder where he comes up with this stuff. Contradicts his statements in message 15,

If you NEED it, it isn't headroom - not to hard to understand?

then gives a max 75 watts power rating for monitors.

I'm starting to think the best answer on the forum is, It depends.

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Just for grins I once powered down some medium efficient monitors (95db/1W/1M) to 75 watts and had no problem getting them to max GBF with SM58's with just a tiny amount of clip limiting going on. That calculates out to 108.5 db at the performer's ear plus whatever the backline and adjacent monitors contribute (+3-6db?). I'll stand by my statement that you should be using ear protection at that level. Heck, in the bad old days we used a 150w mono amp running 3 monitors and I used ear protection. I'm presently using some 98db efficient monitors with 265 watts each so 117db at the performer's ears. I was plenty happy with the 150w each from RMX850's but went to IPR1600's for the MUCH lower weight.

[oldschooler]

Having headroom also means you don't have to run your gear as hard. 

Using math to do specs in real life does not always work out. I honestly don't belive your little monitor can do 117 dbs constantly with 265 watts. They would have to do peaks into the 120 range to maintain 117 db.

Please do not mention the good old days. When I started bands weren't even asking for monitors, only the singers got them or everyone shared one mix. You were using 150 watts amps because that was all we had at the time. Weren't you drooling for bigger amps? I know I was. What we know/have now is light years from even 10 years ago.

Give your monitor to a drummer who hits hard, I bet your 75 or 250 watts isn't going to work for him.