Hello

Currently I have a pair of JBL JRX115's witch output 250 watts at 8 ohm's each.

Im starting todo bigger gigs now and find im having to push them more and more and was wondering about putting bigger drivers in the same speakers i already have (to help lower the cost of upgrading)

obviously I would upgrade both the 15 inch driver and the tweeter and try to keep the ratio the same but would aim to have the new power for the speaker at about 500 watts. I know enough about speaker construction to change drivers ect however changing the crossover inside would be a bit complicated for me. therefore i would aim to keep this the same.

I would aim to put a good quality of drivers I was recommended Fane?

I had also thought about getting a second pair of the JBL's however transport is already an issue (it just about all fits in my 206!). which makes that a less then ideal solution


Thank you for your time and advice

Jack

Most people would rate the JBL drivers you have as good anyway. (I wouldn't rate Fane as a "better" make) At 98 db sensitivity and max SPL of 128 dB I doubt that you would get drivers with much better performance, certainly not without paying more case than you apparently have (including a amplifier upgrade for more power?)
The horn driver and crossover would need to be uprated too, anyway.


If you find you lack volume I have few suggestions
1.If you are not using speaker stands get some.
2.You could get another pair of JBL JRX115s or a pair of JRX112s to go on top of the 15s (same power and also 8 ohms so, if, as I suspect, your amplifier can handle a 4 ohm load, no new amplifier needed.)

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The PSR

What amp are you using? The JRX is rated at 250/1000 watts, best suited to an amp of around 500watts. Doubling the power to the speakers would only increase the output by 3dBs which ain't a huge difference. If you decided to change the drivers you would need to upgrade the crossovers as well, which would be expensive. Realistically it would be cheaper and better to just sell the JRX's and buy some better speakers.

PSR got there first (and I'd agree with virtually all he says) I'd add that doubling up on the speakers rarely gives much of an improvement and can create more problems with phase issues etc.

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Turn it down lads (but only a little bit)

Edited by Sam Spoons (22/02/13 11:25 PM)

IMHO Sam's pretty much on the money in all depts!

If you do get new speakers don't worry TOO much about power-handling - as long as they're not rated at something like 15 watts. But do check their efficiency - the higher the number the better; you need to be looking somewhere in the mid/high 90s or low 100s.

Ok so at the moment i have the JBL's being ran by a behringer EPX2000 (i think its about 350 watts at 8 ohm)

i also have a pair of 400 watt 8 ohm B&C design subs which are custom built being powered by a behringer EP4000 (about 550 watts at 8 ohm) (i know the behringer amps arnt the best but they are all i can afford and seem todo the job well enough for the moment)

my main issue is that as some of my bigger gigs im struggling to push vocals out hard enough to really sit above everything else as i would like them. what do you feel would be the most cost effective way to solve this? as obviously i was mistaken with my idea about bigger drivers....


finally a few more general questions....
what does efficiency actually mean? is it the same as sensitivity? and also what make a more power speaker then better? obviously the loader i want to go the more air i need to displace. does the higher wattage make the driver move more ? therefore displacing more air?

thanks for all your help

Jack

Behringer amps are cheap but usually punch above their weight in terms of bang/buck ratio.

Regarding volume, as you surmise, to get it louder you need to move more air, which in turn needs more power, but the increase is not linear, to get 'twice as loud' for the same speaker efficiency (which is more or less the same as sensitivity in this context) you need ten times the watts.

Do you run the whole band through the PA (if not you don't need bins/subs)? if so your mix technique is probably causing the issue with inaudible vocals. (if not it'll most likely be those pesky guitar players :-). try eq-ing the guitars to leave space for the vocals, scoop a bit of mid range from the guitars and slightly boost the vocals at the same frequencies (+&- 3/4dBs around 1-3KHz, the presence range) If that still doesn't cut it you'll have to turn everything else down (which will probably improve the overall sound anyway).

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Turn it down lads (but only a little bit)

Do you use the subs a lot and what do you use for a crossover when you do?

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Ohm's Law states, "Your PA isn't as powerful as you think it is".

What music do you play ... are you a live band ? DJ ? live dance act ?

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PA Hire Surrey
Lighting Hire Surrey

Mainly sort of friends rocks bands ect have done some thethre shows and a choir before aswell

Ok maybe i need to rephrase my question even thought i will think about the EQ on my vocals. But I"m happy with the sound i get at the moment and so are the bands. its just when I'm in some of my bigger venues (sort of average village hall size) and im trying to get a rock band to be load enough to be a rock concert! Im feeling like i pushing everything quite hard and would like just more power to be able to back the faders off a bit and have room to play with the volume more throughout the concert.

so what would be the most cost effective way to increase the output of my PA? would it be to get a second set of JBL's? then get a bigger amp to power them both? how would i go about connecting them to give me the best impedance?

I'd prefer an alternative to more boxes as transporting my gear is already a work or art however what will be will be and ill find a way to do it

Do you find you get distortion when you push the rig(Often heard as a muddying of the sound)? If so try borrowing or buying a bigger amp for the subs (something that'll give around 800watts per channel into 8ohms) and using the EP4000 for the tops, that will give you a little more headroom and won't increase your box count.

A couple of things to consider if you do go for extra boxes, first, they'll work better if they are identical. Also consider that the lower load Impediance will make your amps work harder.

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Turn it down lads (but only a little bit)

okay. but surly pushing the drivers abover there stated RMS isnt really good for them? ive been reading another thread that has been up here recently regarding power ratio between amplifiers and speakers? surely if my amp has 550 watts at 8 ohms then if i turn it up full and keep it floating around the mid point of my levels it will be pushing out about 400 watts ? which is what the speaker is ment to have? what would the advantage of going to 800 ?

what effect does the impedance have? i always had it in my head that an 8ohm speaker for some reason was loader then a 4 Ohm speaker due to looking at amps and that they pushed less power out at 8 ohm? now i have looked into it more i can see just how stupid i was.

but if amps can push more power at 4 ohm thus it costs me less to buy them what is the advantage to an 8 ohm system?

also if i go out of the link on the back of my JBL to another JBL what will the impedance be? (my JBL's are 8 ohms atm)

Quote Dodger:

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okay. but surly pushing the drivers abover there stated RMS isnt really good for them? ive been reading another thread that has been up here recently regarding power ratio between amplifiers and speakers? surely if my amp has 550 watts at 8 ohms then if i turn it up full and keep it floating around the mid point of my levels it will be pushing out about 400 watts ? which is what the speaker is ment to have? what would the advantage of going to 800 ?

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Theres a good thread here on this very subject (may be the one you refer to). http://www.soundonsound.com/forum/showflat.php?Cat=&Number=1034999& ;page=0&view=collapsed&sb=5&o=365&fpart=1#1034999 Basically speakers can cope with far more than the quoted RMS watts as long as it is only for brief periods (the 'rest' time between 'spikes' of over power allow the voice coils to cool). Amps can't provide power over their rated output without introducing some distortion. The distortion tends to be in the hi mid and treble which is potentially damaging to speakers. Hopefully this is a very much simplified version of the other thread BTW.

The upshot is that the most effective combination of amps and speakers have the amps RMS rating around 1.5 to 2 x the speakers. This helps avoid the amps distorting before the speakers are running at full power. Of course if you then drive the overrated amp into distortion you can damage your speakers but so could an underrated amp so you need to use your ears and if it starts to sound crunchy, turn it down a bit.

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what effect does the impedance have? i always had it in my head that an 8ohm speaker for some reason was loader then a 4 Ohm speaker due to looking at amps and that they pushed less power out at 8 ohm? now i have looked into it more i can see just how stupid i was.

but if amps can push more power at 4 ohm thus it costs me less to buy them what is the advantage to an 8 ohm system?

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Not a lot really (a bit kinder to your amps maybe).

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also if i go out of the link on the back of my JBL to another JBL what will the impedance be? (my JBL's are 8 ohms atm)

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Using the link jacks puts the speakers in parallel so the resulting impedance is 4ohms, I suspect most speakers are 8 ohms just so you can do this (many amps require a load of at least 4 ohms).

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Turn it down lads (but only a little bit)

So to blown speaker is actually caused by the voice coil over heating too much?

so it is ok to go over the RMS power when actually powering the amp? i always thought you had a more powerfull amp as to avoide clipping the amp? not so you could over power the speaker ? surely with regards to "looking after" speakers and equipment you shouldn't over power them ?

what actual negative effect will over powering them have?

sorry for all the stupid question i have a basic understanding of all of this just wanting to take my knowledge to the next level and really understand how it all fits together

and if i constantly over power my JBL's with say a 500 watt amp ? i understand (i hope) that if i turn up the amp to full it will output a maximum of 500 watts when i push the amp just before clipping ? so would it be safe to assume during a normal gig with a fairly standard input it will put about 400 watts average into the speaker ? surly that would damage it?

thanks for all you help so far by the way guys i really really appreciate it

Quote Dodger:

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So to blown speaker is actually caused by the voice coil over heating too much?

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Yes

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so it is ok to go over the RMS power when actually powering the amp?

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?.... best practice is to use an amp with an RMS rating of 1.5-2x the RMS rating of the speaker

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i always thought you had a more powerfull amp as to avoide clipping the amp?

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Yes

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not so you could over power the speaker ? surely with regards to "looking after" speakers and equipment you shouldn't over power them?

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Correct

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what actual negative effect will over powering them have?

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Using an amp with 1.5-2x the RMS rating of the speaker will only 'overpower' (sorry, my poor choice of words) the speakers if you let it, avoid distortion and you won't be 'overpowering' the speakers as the average watts the amp is producing will be below the speakers 'damage tolerance'.

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sorry for all the stupid question i have a basic understanding of all of this just wanting to take my knowledge to the next level and really understand how it all fits together

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There are no stupid questions if you genuinely want to know the answers

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Turn it down lads (but only a little bit)

Depends on the impedance of the driver.... what is the load on the amp ?

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PA Hire Surrey
Lighting Hire Surrey

Quote Dodger:

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and if i constantly over power my JBL's with say a 500 watt amp ? i understand (i hope) that if i turn up the amp to full it will output a maximum of 500 watts when i push the amp just before clipping ? so would it be safe to assume during a normal gig with a fairly standard input it will put about 400 watts average into the speaker ? surly that would damage it?

thanks for all you help so far by the way guys i really really appreciate it

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If you 'constantly' overpower your JBL's you will damage them. But, while your 500 watt RMS amp can produce a clean, undistorted 500 watts when presented with, say, a snare drum hit, the average level of the music containing the snare drum hit will be well below 500 watts (as long as you avoid clipping on all but the very loudest transients). The extra watts allow the amp to reproduce things like cymbal/snare drum hits, percussive piano notes or other sounds with a large transient attack cleanly and without distortion. Your speakers can handle 250 watts RMS (i.e.average) and up to 1000 watts peak (for a brief transient) so a 4/500 watt amp is fine and will not 'overdrive' your speakers). As an example, we run 5x8000 watt Crown iTech power amps on our big rig and each can happily be powered by a single 13 amp socket, the equivalent of around 3000 watts, the average power drawn from the mains is under 40% of the momentary peak, the iTech's do have some clever stuff going on but a mains draw of 50-60% of the suggested RMS watts (audio) rating would be usual for a solid state PA amp.

HTH

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Turn it down lads (but only a little bit)

There is sooo much more to it than just power ratings, thing like speaker cable play a huge part in all this and that just the start of it. I've seen drivers burn themselves out due to long speaker cables run (using 1.5mm) due to NO cone control / very poor damping. They sit there just flappying about until ..... pop

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PA Hire Surrey
Lighting Hire Surrey

Quote TSH-Tim:

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There is sooo much more to it than just power ratings, thing like speaker cable play a huge part in all this and that just the start of it. I've seen drivers burn themselves out due to long speaker cables run (using 1.5mm) due to NO cone control / very poor damping. They sit there just flappying about until ..... pop

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Yup, I realise it's a huge, complicated subject and generalisations can be dangerous. However, I think the OP is at the beginning end of the PA learning curve so I tried to give a reply he might find easier understand without misleading him. Please do correct me if I get it wrong, I'm hear to learn too

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Turn it down lads (but only a little bit)

I would suggest fitting 15" JBL2226 4 ohm LF and 2426 HF, and biamping, that will fire em up a bit. Not too expensive off eaby these days. Use MINIMUM 2.5mm cables. (4 core for biamping) I use 4mm core cables for most long runs, I once upgraded from 1.5 to 4mm in a in house installation. The far side from the amps doubled in volume!
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Used that may be a possibility but new it's an expensive prospect, the drivers alone are around £380 each and an active crossover is at least another £100, then you need another amp to drive the tweeters, say £300. You could buy a pair of PRX 635s http://www.thomann.de/gb/jbl_prx_635.htm (three way, 3 x 500 watt Crown amps, 135dB SPL) for about the same money and you'd still have the old kit to sell.

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Turn it down lads (but only a little bit)

Edited by Sam Spoons (06/03/13 03:28 PM)

What? You can pickup 2226 and 2426 here for around $300au, about 200 pounds, if anything prices I have seen on UK ebay are less than here. He has space issues and seems to need the size boxes ha already has. A 200W/ch amp shouldnt be that much new!

Quote Falconhell:

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What? You can pickup 2226 and 2426 here for around $300au, about 200 pounds, if anything prices I have seen on UK ebay are less than here. He has space issues and seems to need the size boxes ha already has. A 200W/ch amp shouldnt be that much new!

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If the OP had an old pair of decent birch ply cabs with old low powered drivers I'd totally agree with you about replacing the drivers with some efficient modern ones but the JRX115's are budget MDF cabs costing around £200 each over here.

There are no 4ohm 222/2426 drivers on eBay at present, current or completed but even at £200 a unit by the time you've added a crossover and extre power amp you must be looking at around £1000.

These would be a much better bet http://www.ebay.co.uk/itm/JBL-PRX612M-2-Way-Active-PA-Speaker-Stage-Monito r-/360604948995?_trksid=p2047675.m1850&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D 1%26asc%3D14587%26meid%3D6070409096569616446%26pid%3D100011%26prg%3D1005%26rk%3D1%26sd%3D3 60575814560%26 for another £150 which the JRX's should fetch on eBay. They'll give an extra 6dB at the expense of a small reduction in bass (but the OP has B&C bins) and take up less space in the car (and no power amp needed).

I'n't it fun spending somebody else's money

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Turn it down lads (but only a little bit)