ONLY 3dB increase? In order to get another 3dB from my subs i should buy another 4 (i have 4 horn loaded 18's and 2 of these amps).
So doubling the amount of boxes vs connecting amps a bit different to get almost the same thing... I'm quiet sure the second option is a lot more price efficient lol...
The other thing is, yes my drivers may not work perfect when pushed with 1000w each. But then i won't run the amps as hard as i can and i won't have to fear clipping. Now i have to run them at the absolute limit of what they can do and fear clipping all the time. They usually touch red sligtly during the entire night.
I mean basically you are saying it's okay that the amplifier is under the drivers RMS rating, no it's not okay. The amp sould idealy be equal to the drivers program power (2x RMS) and then you can run it slightly above 50-60% power so in peaks it will still do the job with no problems insted of clipping like hell and destroying your boxes. Of course, you put limiters in the line and save the night, but that's all far from ideal world.
IF i can get more power out of my amps, shaying that i shouldn't makes really no sense to me.
EDIT: And yes, RCF L18S800 are 800w RMS. In practice (i allready tested this with more powerfull amps) They take 800w for breakfast and if set up right will run great when you give them 1000w per driver, they are not pushing out any significant distortion and punch significantly harder. Especially when we are talking about 4 of them in a mono block.
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Your amp is rated @ 500W into 8ohms and also 800W into 4ohms.
When the two amps are bridged you get double the power into double the load impedance.
Your bridged amp can do 1000W into 16ohms, or 1600W into 8ohms.
That last is equal to your double the rated capability of your speakers.
One bridged amp driving one speaker gives you an easy 800W to 1000W into your 8ohms speaker.
You have two amps, so your can get 1600W +1600W into 8+8ohms and run them @ 60% for good reliability.
Just go out and buy two more stereo amps rated for 800W+800W into 4+4ohms.
You now have a total 6400W to drive 3200W of speakers.
And little risk of blowing them up. Equals pleased customers.
When the two amps are bridged you get double the power into double the load impedance.
Your bridged amp can do 1000W into 16ohms, or 1600W into 8ohms.
That last is equal to your double the rated capability of your speakers.
One bridged amp driving one speaker gives you an easy 800W to 1000W into your 8ohms speaker.
You have two amps, so your can get 1600W +1600W into 8+8ohms and run them @ 60% for good reliability.
Just go out and buy two more stereo amps rated for 800W+800W into 4+4ohms.
You now have a total 6400W to drive 3200W of speakers.
And little risk of blowing them up. Equals pleased customers.
Of course i can go buy more amps, i can also build more boxes that way... That"s not the point of all this. I want to find out if my amps can do 2 ohms stereo and 4 ohms bridge. That"s why i posted the question. I need a way to get that data wihout having the datasheet. What i will do with my amps later is my problem. But now i need to find out if they can do 2 ohms stereo.
If they will export 2000w into 4 ohms continuously , i can run these drivers with an average of 700w, not pushing them into distorion and not risking clipping. With the stereo configuration they are hitting the limiter often and still getting less power then they can handle. So bridge configuration if possible is simply a light year better
If they will export 2000w into 4 ohms continuously , i can run these drivers with an average of 700w, not pushing them into distorion and not risking clipping. With the stereo configuration they are hitting the limiter often and still getting less power then they can handle. So bridge configuration if possible is simply a light year better
I explained earlier how the specification do not address the difference between 2r0 resistive dummy test load and 2ohms reactive speaker load.
You can claim 2r0 resistive load and that does nothing about confirming 4ohms speaker capability.
Go back and read what I typed.
Now I have many times suggested that the minimum resistive load that an amplifier needs to drive and remain stable should be half the speaker rating load.
And preferably 1/3rd of the speaker rating.
i.e. I expect any 8ohms capable amplifier to be easily able to drive a 4r0 test load and should also be able to drive a 2r6 test load.
Halve those numbers for a 4ohms capable amplifier.
Now compare those numbers to that assumed specification . It fails to match up.
As an aside R.Cordell says that a capable amplifier should be able to drive 180% of rated power into a test load that is half the rated load. On that test your assumed spec fails.
Is the message getting through?
And still no one else dares to give you any guarantee.
You can claim 2r0 resistive load and that does nothing about confirming 4ohms speaker capability.
Go back and read what I typed.
Now I have many times suggested that the minimum resistive load that an amplifier needs to drive and remain stable should be half the speaker rating load.
And preferably 1/3rd of the speaker rating.
i.e. I expect any 8ohms capable amplifier to be easily able to drive a 4r0 test load and should also be able to drive a 2r6 test load.
Halve those numbers for a 4ohms capable amplifier.
Now compare those numbers to that assumed specification . It fails to match up.
As an aside R.Cordell says that a capable amplifier should be able to drive 180% of rated power into a test load that is half the rated load. On that test your assumed spec fails.
Is the message getting through?
And still no one else dares to give you any guarantee.
Well, this is true yes. The reality is, even if the TVA series has the same specs as the PAS series, that still won't mean it's realisticaly capable of getting raped at 2 ohms per channel and surviving, since it's specs tell us it can probably only do test loads at 2 ohms.
2 more questions came to my mind...
Think about this... even if the amp is not capable of doing any serious job at 2 ohms stereo... what if i still connected a 4 ohm load at the amp in bridge.
BUT then watch out not to run it anywhere over 50-60% power.
If i did that it would still deliver the same power to my subs that i now get (about 500-550w). But in case of a somewhat heavier peak, instead of starting to clip it would probably just hit the driver with 650-700w and go back to normal. Witch would be a lot healtier for the voicoiles then clipping is.
If i'm right, you shouldn't go below the minimal rated impedance because to much current going trough the amp will overheat it. If it runs under 500-600w per channel all the time, but just sometimes goes above that, it won't overheat.
Would this configuration really be safer for my boxes or not?
I mean... all the time i'm thinking about the fact that my amp has the capability of delivering 900w per channel but i can't use that because i have 4 8ohm boxes and 2 amps/4 channels. If i had 4 ohm drivers i would get that power but now i don't seem to be able to no matter what i do, right?
800W into 4r0 is equivalent to 20Apk to the 4r0 resistor load.
600W into 2r0 is equivalent to 25.5Apk to a 2r0 resistor load.
The peak current into a reactive speaker without a passive crossover is likely to be around 150% of that i.e. ~36Apk, that's 3.4times more heat in the output stage.
And still no other Member is willing to step in and guarantee that your 4ohms rated amplifier will survive PA duty driving that 4ohms load in bridged format.
Can't you get the message?
600W into 2r0 is equivalent to 25.5Apk to a 2r0 resistor load.
The peak current into a reactive speaker without a passive crossover is likely to be around 150% of that i.e. ~36Apk, that's 3.4times more heat in the output stage.
And still no other Member is willing to step in and guarantee that your 4ohms rated amplifier will survive PA duty driving that 4ohms load in bridged format.
Can't you get the message?
Wait, so you are telling me giving 1000w to a 4 ohm load in bridge mode (from both channels) is not exactly the same thing as giving 500w to two 8 ohm loads, one on each channel?
I mean, in order to get the same power on a different impedance the required voltage is going to be different. But the amount of electricity getting trough an amp is still the same.
I mean, in order to get the same power on a different impedance the required voltage is going to be different. But the amount of electricity getting trough an amp is still the same.
Yes he is, YOU are totally incorrect - in bridge mode the amp would be feeding 500W per channel into 2 ohms - presumably killing the amp?.
The voltage is doubled, so you need to increase the impedance to prevent a massive overload.
Bridging is quite simple, it provides exactly the same power as stereo, BUT into one speaker of twice the impedance.
With my knowledge of electrotehnics (witch obviusly isn't that great) this does not make any sense to me.
Wattage is Current * Voltage. The amount of heat the amp is going to be generating is dependant on the amount of electricity going trough it and only on the amount of electricity going trough it.
If you have X watts getting from the wall into the speaker, and in the proces going trough the amplifier. And you change the paramiter of the speaker impedance, but DO NOT change the wattage you are giving to the speaker, then the only 2 parameters that change in the amplifier are the voltage and amperage going from the amp to the speaker. One of them goes up, the other one goes down, depending on what you did. But you are still giving the speaker the same amount of power (wattage) so the amp can not produce any more heat then it did in the other configuration that exported the same power. The only problem that can happen is that you hit the voltage limit of the amp witch will manifest as clipping, but that's not a problem we are now talking about.
Now, you wrote: "the amp would be feeding 500W per channel into 2 ohms - presumably killing the amp?."
From as much as i understand, this is not possible. The only reason that any amp shouldn't work blow the lowest specified impedance allowed is the fact that IF you make it run at 2 ohms (and it shouldn't go below 4) It will then BE ABLE to export more then 900w per channel if you turn it up but it's components can not survive that and therefore you will destroy the amp by pushing it at 2 ohms.
BUT if you take care about not passing 900w per channel the amplifier is still not exceeding it's max load.
In short terms, as much as i understand
900w @ 2ohms and 900w @ 4 ohms is exactly the same thing but with different current and voltage parameters.
50V @2ohms is very different from 50V @4ohms but that's a different story.
Now, i'm not claiming i'm right, but if i'm not then i'm getting a certain part of this completly wrong... i'd really like to learn witch one since this is usefull knowledge to me. Thanks!
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You WILL blow it - doesn't matter how 'careful' you are, it will get killed.
Why are you trying to bridge anyway? - use the correct speakers instead.
Why? I set the amp potentiometers at 50% and put a brickwall limiter at 0dB in the line before the amps. If the limiter is good there is no way the amp is going to export more power then 50% power then it COULD at the impedance i'm currently running it at.
This is not about bridging the amps anymore, i'm probably not going to even try doing it. But i want to learn something because one of us is getting some part wrong. It might be me so i want to learn what i don't know. In the post before this i explained why i think you could run any amp at any impedance as long as you take care about not letting it pass it's max wattage output limit. And it's voltage limit... you don't want it clipping of course.
You're forgetting about current restrictions as well, it's not just wattage ones.
Certainly for PA use you don't want to risk anything so potentially disastrous.
So the amp has got current restrictions undependat on everything else?
If it can't export more them 30 amps then it can't do it no matter if the output voltage is 1 or 100V ?
Essentially.
There's no good reason to use too low an impedance load, and plenty of reasons not to.
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