Multiple Speaker power question

[johndough247]

Simple question, though i've read the amp/speaker/impedance FAQs and not getting a clear enough (to me) answer.

In a 450W (@ 4 ohms) 2x10 combo amp, wired in parallel (with each speaker rated at 8 ohms for a total of 4 ohms), is each individual 10" speaker getting 450W of power or is it split among them (i.e. 225W per speaker)?

I'm buying some replacement speakers for my combo amp, and I have a tough time choosing between the Eminence legend BP102's or the Eminence Delta 10's. The BP102's have better low frequency response on paper and TB opinions (40Hz, delta 10 is 65Hz)...but the delta 10's have higher power handling (350W, the BP102 is 200W). I play several styles, mostly r&b, reggae, neo-soul type stuff...I play a 5 string so low end response is crucial)

I'm a total novice to all this, and I don't expect to get thunderous sub-bass from a 2x10...just looking for the best match for my 450W combo without under/overpowering (oh and both speakers are the exact same price). Help!

[playerunk]

the power is split among the drivers.

i am not familiar with any of the 2 speakers but i can tell you this : throwing a better on paper speaker into a box doesn't guarantee success.. [because the box was designed for the speaker that it came with].. you can try though and post you thoughts here.

[johndough247]

Originally Posted by playerunk

the power is split among the drivers.

i am not familiar with any of the 2 speakers but i can tell you this : throwing a better on paper speaker into a box doesn't guarantee success.. [because the box was designed for the speaker that it came with].. you can try though and post you thoughts here.

Well the combo amp is a Behringer BX4210A...I bought it blind after testing it in a store today (yea bad idea i know)...heard from everywhere afterwards that the aluminum speakers are notorious for tearing easily. I just wanted to nip this in the bud before I take it on a gig and suffer the same fate. Many recommend the BP102's as a much better replacement, so I was just trying to learn more of the science behind it.

Yea i know, working from specs alone is a bad idea, thats why i'm here seeking (hopefully) more knowledgable/experienced opinions

[Matthijs]

The power is divided over the speakers. There's no way you can tell on forehand if a replacement speaker, and wich speaker will sound better without doing all the math or by trying it out. Since you can't do the math, as you don't have all the specs for the cab and speakers, there's only one way: try. But be prepared to reïnstall the original speakers.

The problem is: your reason for replacing them is because you fear the original ones will break during a gig. Same goes for the replacements: if the tuning frequency doesn't match, the most likely time they will break is also with a lot of bass at high volumes during a gig. The rated wattage is not a very good way to predict how much low end watts the speakers can cope with, you need the math for that.

So I recomend not replacing the speakers. Best way to tackle your problem is with adding an extention cab you can trust (if that's possible since the cab is rated at a total 4 ohms). Or replacing the whole combo. Or just using your ears while giging and taking care not to overload the combo. The last part may work out surprisingly well

[Jaco who?]

Originally Posted by johndough247

Yea i know, working from specs alone is a bad idea, thats why i'm here seeking (hopefully) more knowledgable/experienced opinions

It's not a bad idea at all, the problem is you don't have any of the TS specs that matter, and behringer most likely won't give them to you.

[johndough247]

Originally Posted by Matthijs

The power is divided over the speakers. There's no way you can tell on forehand if a replacement speaker, and wich speaker will sound better without doing all the math or by trying it out. Since you can't do the math, as you don't have all the specs for the cab and speakers, there's only one way: try. But be prepared to reïnstall the original speakers.

The problem is: your reason for replacing them is because you fear the original ones will break during a gig. Same goes for the replacements: if the tuning frequency doesn't match, the most likely time they will break is also with a lot of bass at high volumes during a gig. The rated wattage is not a very good way to predict how much low end watts the speakers can cope with, you need the math for that.

So I recomend not replacing the speakers. Best way to tackle your problem is with adding an extention cab you can trust (if that's possible since the cab is rated at a total 4 ohms). Or replacing the whole combo. Or just using your ears while giging and taking care not to overload the combo. The last part may work out surprisingly well

Your logic makes total sense (oh yea and believe me, I'm quite careful with that sorta thing (not overloading), I love my equipment and my EARS! ). However getting an extension cab is both costly and impractical in my situation (have nowhere to store it, and shipping a cab here (caribbean) would cost hundreds in weight and customs), and the choices here are very slim.

I think I will try the new speakers just for kicks, and if anything, I'll have replacements readily on hand if either one fails.

The tuning frequency would be the resonant frequency right?

[billfitzmaurice]

Originally Posted by johndough247

.but the delta 10's have higher power handling

Moot. What matters is sensitivity, response and displacement, not watts. The only way to make a definitive comparison is through comprehensive modeling of the drivers in the intended enclosure.

[Matthijs]

Originally Posted by johndough247

The tuning frequency would be the resonant frequency right?

Not the resonant frequency of the speaker: for the whole ported cab. That's a result of the internal volume, the dimensions of the port and several spec's of the speaker.

There's nothing against experimenting with replacement speakers, just remeber that's what it is: an experiment without a predictable outcome. It'might very well be worse than the originals.

If you take this in account in choosing between the delta's and the bp 102 I think the power question is not the most important thing. The delta's are much louder and cover a broader frequency range. The legend is good in the very low part, but for most people will not put out enough high mids.

If you want the combo to sound deeper the legend might be the best bet. If you want it to be loud and not break up, the delta's are the better bet. I doubt the delta's have less low end compared to the originals.

[BassmanPaul]

You are trying to make a silk purse from a sow's ear. Without doing the math, as Bill posted, all you'll get is a crapshoot. If you are lucky you might get an improvement but you more than likely won't.

[Gero]

Originally Posted by billfitzmaurice

Moot. What matters is sensitivity, response and displacement, not watts.

Not if he's worried about how much power is going to go to each individual speaker (as to not cause damage), which was the orig question.

[johndough247]

Originally Posted by Matthijs

Not the resonant frequency of the speaker: for the whole ported cab. That's a result of the internal volume, the dimensions of the port and several spec's of the speaker.

There's nothing against experimenting with replacement speakers, just remeber that's what it is: an experiment without a predictable outcome. It'might very well be worse than the originals.

If you take this in account in choosing between the delta's and the bp 102 I think the power question is not the most important thing. The delta's are much louder and cover a broader frequency range. The legend is good in the very low part, but for most people will not put out enough high mids.

If you want the combo to sound deeper the legend might be the best bet. If you want it to be loud and not break up, the delta's are the better bet. I doubt the delta's have less low end compared to the originals.

Fair enough...Volume is not an issue. For most the medium to large venue events I do, A Bass rig is provided. This is mostly to rehearsals/small venues. besides...given the answer to my original question...wouldn't 2 deltas (350W each) be underpowered by a 450W head?

Originally Posted by BassmanPaul

You are trying to make a silk purse from a sow's ear. Without doing the math, as Bill posted, all you'll get is a crapshoot. If you are lucky you might get an improvement but you more than likely won't.

If I really had my choice and money was no object...Behringer would be the last choice on my mind. this is just a temporary amp (will probably be moving from here in 2 years or so) as we don't have decent music stores anywhere nearby.

As i said earlier, i'm a novice at building an amp setup but i'm not delusional...I didn't expect much and I know it's a crapshoot...I was hoping someone else did it before me and could report back (i.e. took this same combo and replace with the same drivers)

Originally Posted by billfitzmaurice

Moot. What matters is sensitivity, response and displacement, not watts. The only way to make a definitive comparison is through comprehensive modeling of the drivers in the intended enclosure.

Got it. It's starting to sink in lol

Well, i'm thankful for all the advice, most of it was what i'd already assumed (was just somewhat rusty on the whole thing)...regardless, i'm gonna buy the BP102's. I'll report back after i've made the switch. Thanks again everyone!

[JTE]

Originally Posted by Gero

Not if he's worried about how much power is going to go to each individual speaker (as to not cause damage), which was the orig question.

Except power ratings on speakers us s pretty meaningless spec. It's the thermal rating- where voice could melts. The speaker would probably be shredded long before that anyway.

Jihn

[JimmyM]

Originally Posted by johndough247

Fair enough...Volume is not an issue. For most the medium to large venue events I do, A Bass rig is provided. This is mostly to rehearsals/small venues. besides...given the answer to my original question...wouldn't 2 deltas (350W each) be underpowered by a 450W head?

besides power handling specs being meaningless, there is no such thing as underpowering a cab. if there was, then you could never turn the volume down on an amp.

[johndough247]

Originally Posted by JimmyM

besides power handling specs being meaningless, there is no such thing as underpowering a cab. if there was, then you could never turn the volume down on an amp.

Always wondered about that lol...so the problem comes from trying to push the cab to a point the amp can't deliver (problem for the amp i mean)? I'm just wondering why some people say it's better to overpower than to under...

[billfitzmaurice]

Originally Posted by johndough247

I'm just wondering why some people say it's better to overpower than to under...

Do the phrase 'Ignorance is bliss' sound familiar?

[johndough247]

Originally Posted by billfitzmaurice

Do the phrase 'Ignorance is bliss' sound familiar?

i'm sorry....what?

[billfitzmaurice]

Originally Posted by johndough247

i'm sorry....what?

Sources where you see references to the under-powering myth simply didn't know what they're talking about; i.e., they are ignorant of the facts. Clipped waveforms that can be created by over-driven amps can hurt tweeters, but that's it. Clipped waveforms have no effect on woofers, and under-powering does not exist.

[JimmyM]

if an amp clips and it causes a speaker to blow, it's because the clipping was overpowering the speaker. if an amp clips and the amp isn't rated to have peak power above what the cab can take, you can clip it all day long and nothing will happen to the speakers. for example, if i plug my b-15 (25w rms, about 50 or 60w peak) into an 810, i could play all day like that and nothing would happen to the cab.

[johndough247]

makes perfect sense, thanks for clearing that up

[BluesBear]

In the PA environment, if you are blowing your horn diaphrams the old adage was, "you need to get a bigger amp".
That was based on the premise that the fastest way to blow a 50 watt driver was to connect it to a 40 watt amp. And that is true because an amp that generates 40 watts of clean power will usually put out well over 80 watts (some over 120 watts) at hard clipping. So you ran a 200 watt power amp for your 50 watt horn under the theory that you'd never drive it hard enough to cause clipping.

Now a cone transducer (loudspeaker) is not as sensitive to clipping as a diaphram transducer (horn driver) but it can still happen.

If you force too much current through a loudspeaker voicecoil it will heat up and pop just like a fuse or a light bulb.
On the other hand if your cone stiffness or your voicecoil support isn't strong enough too much current can cause voicecoil over excursion. That's where the voicecoil and it's support move too far and actually tip. And when a voicecoil tips it usually starts rubbing inside the gap. Not only will the speaker instantly sound like elcrappo but it will either lock up or eventually rub through and open up. And the low frequencies of bass instruments only exacerbated the problem.

I'm sure many of you have seen a blown loudspeaker where if you pushed on the cone you could feel it rubbing inside.* That means that the coil has tipped somewhere along the line. This is why your usually find a larger diameter voicecoil and suppost in a high wattage speaker. The old one inch voicecoil Jensen and Altec Lansing speakers were so easy to overpower. When Altec went to a one and a half inch desigh the power handling was much better. Nowadays it's hard to find a high power speaker with anything smaller than a two inch coil.


*For many years I played through a Peavey MAX Amp. That was basically a CS800 with the preamp from the original Combo 300. When I first got it I was eating the Scorpion speakers in the 410MX top cabinet. I went through three Scorpions in two months. I'd unplug the 410 cabinet (and finish the gig using only my two JBL loaded TL15 cabinets) when I first started hearing that extra harsh distortion. In every case the coil was rubbing but the speaker hadn't actually blown. So I raised my crossover point and never had another problem. And then I could actually get more volume (and clarity) out of the 410 cab.