Log in
Register
Home
Forums
New posts
Search forums
What's new
Featured content
New posts
New profile posts
Latest activity
News
Members
Current visitors
New profile posts
Search profile posts
Features
Log in
Register
What's new
Search
Search titles only
By:
Search titles only
By:
New posts
Search forums
Menu
Install the app
Install
Reply to thread
Home
Forums
Pro Audio
Junior Varsity
JBL SRX / QSC PL236 underpowered?
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Message
<blockquote data-quote="Luke Geis" data-source="post: 82264" data-attributes="member: 3859"><p>Re: JBL SRX / QSC PL236 underpowered?</p><p></p><p>It's a numbers game. If you give a band twice the horse power they need for the gig, That is great! But if you give them less than what is needed, your going to see a lot of red lights!!!!!!! There comes a point when, as an engineer you need to stand up and say NO, you can't have any more.......If you are consistently acquiring gigs where you don't have enough RIG FOR THE GIG, then your going to have problems with equipment life and acquiring new gigs. If you at some point tell the band I only have this much, you can't have any more for this price, you may find a bit more mileage? The bigger the rig the bigger the price. At some point a band will realize that they are going to have to pay for the more part. </p><p></p><p>As far as the other questions asked above. You have to do the math. If you feel your under powered, you probably are. An 1100 watt amp for a speaker that will take 1600 watts for a decent period of time ( program power ) is probably under powered if you want top get near rated specs!!!!!!!! It's very simple. Do the math. I have X watts and a speaker capable of producing X DB with 1 watt of power. Every doubling of watts is equal to 3db of potential gain. You will come to a point where you can factor just how much SPL your able to create. If your speaker is 98db at 1 watt and your powering with an 1100 watt amp, you are going to be able to provide about 30db of gain, or 128db SPL at 1 meter from the speaker. That is at best and running the amp at full tilt. So if your going to have any kind of safety margin ( which most pro's factor 10db's for live audio ) your not going to have a lot of possible SPL. That is to say that with a 10db safety factor your actually only able to produce around 118db of usable SPL out of that speaker with another 10db in the tanks for the what if........... That 118db will only translate into around 88db at 50' from the stage in an outdoor setting. If you run closer to your amp max wattage you may be able to acquire another 10db? Indoors this changes a bit. </p><p></p><p>Being able to get your subs together and centralized can help get some better numbers. You gain 3db when you double the wattage, so placing one sub next to the other nets you another 3db. If you double again you gain another 3db etc. etc. Half space loading, which is what happens when you place the subs on the ground, should get you between 1 and 3db of more gain, but don't count on that. So you ask a second time if 1100 watts is enough? It is if it gets you the needed acoustic volume. If it doesn't, then no it's not enough.</p><p></p><p>As for bands using up whatever they are given, that is true. If you allow a band to run what you brung, they will. I Have no problem with saying NO................ At some point saying NO is important. If the band is paying for a PA that is only capable of a portion of what they want, that is what they are paying for. If they want to pay for more then that is great. In many cases it's not the band paying for it. So saying no, this is all I can do, can go a long way, if the band realizes that it may come back to them for the bad results. I find it helpful to find out what the client desires as a volume need. Loud rock venue volume, middle of the road private venue volume, or quiet background music volume. This can help you a lot in deciding the appropriate sized PA for the GIG. If the client wants rock venue volume, your looking at a PA capable of providing over 110db at the mix position ( even if it's needed or not ), for mid level it about 110-100db at mix position and for background you should shoot for something capable of at least 100db at mix position. This is a guideline for the bar/private party sound guy and does not apply to the large corporate/ rock show providers who will not be asking these questions. If you are a privately owned small sound company and can provide 110db at 50' or more from the stage, your in a good place and you are probably also not going to be asking these questions. If your a bar/ private party guy that is always wondering why you can't get what is needed, now you know....... You have to have equipment that is first capable of the numbers, then properly deploying it so you can back those numbers up. If you already are finding you need more, it's going to cost money to get more. Either double the wattage, or double the number of boxes used. If this is not a viable option in either case then you should be staying away from those types of gigs until you can. </p><p></p><p>In most cases there is a reality of what can be acquired. If you do shows that a lot of volume is needed you can generally get more by running less through the PA! I.E. a bar gig where you only run vocals through the PA. The speaker will get more volume for the vocals, than if you try and run everything through it. If you run guitar, drums, keys and everything else your going to eat up headroom. This means that in order to get one instrument over the top of all the others, is going to eat up even more headroom. If your only having to reproduce one thing you can allocate more wattage to it's reproduction. This means more volume. The lower number of frequencies you have to reproduce, the more energy you can reserve for reproduction. If your consistently running out of headroom, try simply mic'ing less instruments. This should open up some headroom for the instruments that really need more level to be heard. Next is to mix subs on an aux!!!!! If you can do this you will allocate a lot of energy robbing low end sound, away from the tops allowing for more headroom to whatever is needed. The subs will also gain more headroom, by only having to deal with frequencies that they are meant to reproduce. This is a nice trick to try if you have self powered subs!!!!</p><p></p><p>If you send full range signal to your self powered subs you probably find that you have to back the gains down because they start to distort, or the limiter kicks in. But if you run only run bass and kick to them ( via an auxiliary mix ) and even use a crossover before them ( to roll off even more high frequency content ), you should find that you can run the input trims higher and get even more level to those instruments! This can be acquired by doing the same thing for a conventional unpowered system with a x-over. Running the subs on an aux free's up headroom and can allow for more volume of the amplified instruments before clipping. This effect is also helped by the fact that you can tune each part of the system to be optimized for it's intended reproduction. Food for thought.</p></blockquote><p></p>
[QUOTE="Luke Geis, post: 82264, member: 3859"] Re: JBL SRX / QSC PL236 underpowered? It's a numbers game. If you give a band twice the horse power they need for the gig, That is great! But if you give them less than what is needed, your going to see a lot of red lights!!!!!!! There comes a point when, as an engineer you need to stand up and say NO, you can't have any more.......If you are consistently acquiring gigs where you don't have enough RIG FOR THE GIG, then your going to have problems with equipment life and acquiring new gigs. If you at some point tell the band I only have this much, you can't have any more for this price, you may find a bit more mileage? The bigger the rig the bigger the price. At some point a band will realize that they are going to have to pay for the more part. As far as the other questions asked above. You have to do the math. If you feel your under powered, you probably are. An 1100 watt amp for a speaker that will take 1600 watts for a decent period of time ( program power ) is probably under powered if you want top get near rated specs!!!!!!!! It's very simple. Do the math. I have X watts and a speaker capable of producing X DB with 1 watt of power. Every doubling of watts is equal to 3db of potential gain. You will come to a point where you can factor just how much SPL your able to create. If your speaker is 98db at 1 watt and your powering with an 1100 watt amp, you are going to be able to provide about 30db of gain, or 128db SPL at 1 meter from the speaker. That is at best and running the amp at full tilt. So if your going to have any kind of safety margin ( which most pro's factor 10db's for live audio ) your not going to have a lot of possible SPL. That is to say that with a 10db safety factor your actually only able to produce around 118db of usable SPL out of that speaker with another 10db in the tanks for the what if........... That 118db will only translate into around 88db at 50' from the stage in an outdoor setting. If you run closer to your amp max wattage you may be able to acquire another 10db? Indoors this changes a bit. Being able to get your subs together and centralized can help get some better numbers. You gain 3db when you double the wattage, so placing one sub next to the other nets you another 3db. If you double again you gain another 3db etc. etc. Half space loading, which is what happens when you place the subs on the ground, should get you between 1 and 3db of more gain, but don't count on that. So you ask a second time if 1100 watts is enough? It is if it gets you the needed acoustic volume. If it doesn't, then no it's not enough. As for bands using up whatever they are given, that is true. If you allow a band to run what you brung, they will. I Have no problem with saying NO................ At some point saying NO is important. If the band is paying for a PA that is only capable of a portion of what they want, that is what they are paying for. If they want to pay for more then that is great. In many cases it's not the band paying for it. So saying no, this is all I can do, can go a long way, if the band realizes that it may come back to them for the bad results. I find it helpful to find out what the client desires as a volume need. Loud rock venue volume, middle of the road private venue volume, or quiet background music volume. This can help you a lot in deciding the appropriate sized PA for the GIG. If the client wants rock venue volume, your looking at a PA capable of providing over 110db at the mix position ( even if it's needed or not ), for mid level it about 110-100db at mix position and for background you should shoot for something capable of at least 100db at mix position. This is a guideline for the bar/private party sound guy and does not apply to the large corporate/ rock show providers who will not be asking these questions. If you are a privately owned small sound company and can provide 110db at 50' or more from the stage, your in a good place and you are probably also not going to be asking these questions. If your a bar/ private party guy that is always wondering why you can't get what is needed, now you know....... You have to have equipment that is first capable of the numbers, then properly deploying it so you can back those numbers up. If you already are finding you need more, it's going to cost money to get more. Either double the wattage, or double the number of boxes used. If this is not a viable option in either case then you should be staying away from those types of gigs until you can. In most cases there is a reality of what can be acquired. If you do shows that a lot of volume is needed you can generally get more by running less through the PA! I.E. a bar gig where you only run vocals through the PA. The speaker will get more volume for the vocals, than if you try and run everything through it. If you run guitar, drums, keys and everything else your going to eat up headroom. This means that in order to get one instrument over the top of all the others, is going to eat up even more headroom. If your only having to reproduce one thing you can allocate more wattage to it's reproduction. This means more volume. The lower number of frequencies you have to reproduce, the more energy you can reserve for reproduction. If your consistently running out of headroom, try simply mic'ing less instruments. This should open up some headroom for the instruments that really need more level to be heard. Next is to mix subs on an aux!!!!! If you can do this you will allocate a lot of energy robbing low end sound, away from the tops allowing for more headroom to whatever is needed. The subs will also gain more headroom, by only having to deal with frequencies that they are meant to reproduce. This is a nice trick to try if you have self powered subs!!!! If you send full range signal to your self powered subs you probably find that you have to back the gains down because they start to distort, or the limiter kicks in. But if you run only run bass and kick to them ( via an auxiliary mix ) and even use a crossover before them ( to roll off even more high frequency content ), you should find that you can run the input trims higher and get even more level to those instruments! This can be acquired by doing the same thing for a conventional unpowered system with a x-over. Running the subs on an aux free's up headroom and can allow for more volume of the amplified instruments before clipping. This effect is also helped by the fact that you can tune each part of the system to be optimized for it's intended reproduction. Food for thought. [/QUOTE]
Insert quotes…
Verification
Post reply
Home
Forums
Pro Audio
Junior Varsity
JBL SRX / QSC PL236 underpowered?
Top
Bottom
Sign-up
or
log in
to join the discussion today!
