Max Voltage output BEFORE you buy

[NCcrashman]

First, I want to say that deciding on a amp if ur new to todays technology is NOT easy! Every time I make my mind up on a amp, I read something that makes me think twice about my decision; product quality being the first factor. I will admit that I truly have "engineer brain" and I re-think things to the point of obsession, but this is really tough.
Now to my question and point of discussion. It seems that amp manufactuers do not list max voltage output. Now, I'm certain this is easy and I have overlooked something, but is it just a issue of getting "close" to the speaker output (in watt's) and hope the amp will hit the max for the speaker? If ur speakers will take a max of 56 volts, how then do we decided if a amp at the local music store will output 56 volts BEFORE we buy it?

SECOND Question: I have been "stressing" looking at 4 ohm output of various amps to make sure it will make enough power for the speakers I want to use when I realized something. If we determine that given a speaker output in wattage, for this example we'll say 400 watts and impedence of 8 ohms, if you add a second speaker (800 watts and 4 ohms) the voltage output is the EXACT SAME! So is it true to say it's not important to have a higher output in watts to run 2 speakers a side instead of 1?

Guy's, I really appreciate it and I know I suck at asking questions. Thanks for putting up with me. I ask questions the way I understand stuff in my mind. I suspect it's probably a bit of uncertainty too! Thanks a lot either way

~Patrick

[doncolga]

I saw this on the forums somewhere:

volts = Square root (watts * ohms)

For my Behringer EPQ 1200 I used driving two T30's each with one KL 3012lf:

volts = square root (600 * 4)
volts = square root (2400)
volts = 48.98

That's going by the published specs. After I got it and actually measured, it would go a good bit higher. Seems most of the gain on the amp can be achieved when setting it to 12 o clock. More gain is achieved by wide open, but not as much proportionally.

[bzb]

^ correct formula

As you'll see in most of the charts, they're measured at 2.83v, or 1W at 1 Meter. Use the formula above and you'll see 2.83v = 1W at 8 ohms.

[SeisTres]

you're over thinking it. alot.

If you're running the labs or kappalites, get something with at least the power ratings of the rmx2450. This will provide enough.

If you want extra headroom and not run the amp balls to the wall everytime, get something like the xti4000 or similar power ratings. Remember, the extra watts aren't "wasted" if they're not used, but keep the amp running cooler and with a longer life.

Between the power compression, limiting, the spikes, the dynamics, headroom and doubling of power for those last 3db, theres no point in over thinking it.

[Tom Smit]

Volts are the push behind the current flow; the higher the volts means more amperes (current flow).

Volts times amps equals watts. If the speaker impedance is lower, that means that more amperes will flow...and that means more watts. So,...4 ohms is less impedance than 8 ohms so therefore more amperes will flow which means a higher number of watts are put out by the amplifier.

Hope this helps.

[NCcrashman]

Thanks guys. It all helps. I spent the entire night looking at amps and 4 ohm ratings. I took a break and did the math for 8 ohm loads and 1 speaker per side and came up with 56.56 volts (400 watts x 8 ohms = 3200 and the sqr root being 56.56). So just for giggles I did it for 4 ohms and like a idiot said "duh..their the exact same"..lol. Even with extra power, the MAX I want to push these speakers is 56 volts. One of Crowns new Drive Core amps delivers 550 watts @ 4 ohms. That should be WAY more than enough 2 drive these 4 speakers right? It should be.

[SeisTres]

Thanks guys. It all helps. I spent the entire night looking at amps and 4 ohm ratings. I took a break and did the math for 8 ohm loads and 1 speaker per side and came up with 56.56 volts (400 watts x 8 ohms = 3200 and the sqr root being 56.56). So just for giggles I did it for 4 ohms and like a idiot said "duh..their the exact same"..lol. Even with extra power, the MAX I want to push these speakers is 56 volts. One of Crowns new Drive Core amps delivers 550 watts @ 4 ohms. That should be WAY more than enough 2 drive these 4 speakers right? It should be.

In math terms, yes, in real situations, not really.

I run bp102 and I didn't even find my xls402 adequate for them. It would get the job done but as soon as things started bumping, it would clip like crazy. my xls802 was my preference and even that one clipped twice on the bp102 although 35v is the recommend max for them (granted one of them was when I was testing). Thats why, in my last post, I recommended what I did.

[NCcrashman]

T

you're over thinking it. alot.

If you're running the labs or kappalites, get something with at least the power ratings of the rmx2450. This will provide enough.

If you want extra headroom and not run the amp balls to the wall everytime, get something like the xti4000 or similar power ratings. Remember, the extra watts aren't "wasted" if they're not used, but keep the amp running cooler and with a longer life.

Between the power compression, limiting, the spikes, the dynamics, headroom and doubling of power for those last 3db, theres no point in over thinking it.

Ok, so if ur not going the route of "math" to determine peak output for the speakers, how are you suppose 2 know when 2 much is 2 much and not melt ur vc or shread ur cone? You are absolutely right about me "over-thinking" it..lol. I am just in different "shoes" then most (financially) and I do need 2 know the max voltage input of my speakers sol I don't have issue's of blowing them and having to replace them. The term "headroom" can be really misleading. By doing the math I know the exact MAX the drivers can handle and that should include headroom. So if ur running 4 speakers on 1 amp, should I looking for more voltage output then a single 8 ohm load? I'm just trying 2 get it straight in my own head because if I use the "RMS" numbers, the math says no. You turn it up to the rms voltage and in the case of a 4 ohm load, it's the exact same as a 8 ohm load.

[NCcrashman]

By the way, the speakers I'm talking about here are O'Tops with Delta Pro's in them. They are 400 watts each and 8 ohms impedence.

SEIS: I absolutely agree that having more power then you need is a good thing just for the reasons you mentioned. However, when I set my gear up and run that tone, I need to know what the max voltage is 2 set that amp up properly. After all, gain structure is everything!!

[SeisTres]

Truth is that if you get the graphs for sensitivity, max output, cone displacement, and impedance, there's a lot going on. And again, let's not forgot the whole thing about headroom and peaks they can handle which is altogether different from the rms value. At different frequencies, the speaker behaves very differently, so because of this, I see no point in trying to get exact numbers.

However, the whole thing has been simplified by the numbers Bill provides in every plan (if built correctly) which basically guarantee that under any circumstance, the driver will not be damaged in any way.

So, to sum it up, something like the rmx2450 for premium drivers at minimum, or something like the xit4000 would be nicer still. (do note that when I mention those models is to point out their power output, not that i'm particularly recommending those specif models).

EDIT AFTER LAST POST: LOL, i was going on and on thinking this whole time that subs were cabs being discussed. I really don't feel like editing my post above, so i'll leave it be.

But in this new light, just get something like the rmx2450 to get the most out of your deltas. I guess I'll now include something about running tops

My jacks loaded with betaclones (120rms i believe) can take my xls402 quite nicely all the way up till clipping. Hence the recommendation of the bigger amp. Also I do want to point out that I run my gear hard as I do not like to overcarry. But I don't do it stupidly as i've never had a driver give up on me, ever.

As for limiting on tops, I don't and just watch my levels and listen when your overdoing it; they'll tell you. Even more than on subs, I like ALOT of headroom for those peaks which really bring out the dynamics provided by the tops. And don't worry, you won't hurt them unless you have your amp constantly clipping all night or you raise 100-150hz by 12db

[NCcrashman]

SEIS, you ARE the man! Thank you so much brother. I appreciate the wealth of info. You and I are on the same page I would kill (not really..lol) to get out too Texas and work with you on a gig just to learn.
I REALLY appreciate everyone here and everyone answering me. I prolly stupid to be chasing this dream but the time is right and when I'm done learning, I plan to help teach other the way everyone here has taught me!! I just simply want 2 learn and be the best I can be since I can no longer play.
-Patrick

[Tom Smit]

Here are a couple of threads to read and ponder: http://billfitzmaurice.info/forum/viewt ... =10&t=1886
http://billfitzmaurice.info/forum/viewt ... sion#p3883

[NCcrashman]

Here are a couple of threads to read and ponder: http://billfitzmaurice.info/forum/viewt ... =10&t=1886
http://billfitzmaurice.info/forum/viewt ... sion#p3883

Thanks Tom. Brilliant reads!!

[Tom Smit]

Your welcome.