More power needed for Tempests? (1 Viewer)

[Pete Mazz]

If you have the sub level set at 0dB I would leave it there. I was thinking you may have had it maxed out.

I too find it hard to believe you're not bottoming the Tempests with that much power playing LOTR. It was the only time mine bottomed out. Similar to your setup, BTW. A sealed low Q dual Tempest and a Carver amp bridged to ~800W at 8 ohm.

Pete

 

[David Giesbrecht]

I am going to try what Pete had suggested

Turning the sub out level down didn't make a diffetrence, I was hopeful though.

 

[Jerry Parker]

Maybe your Carver 800 watts was more "true power" than my QSC 900 watts. I know thats sounds kind of silly but I hear this statement come up all the time here and I wonder if it could hold some truth and maybe thats what I'm experiencing.

Ive got a QSC RMX 1450 as well, and as far as I can tell, it easily puts out its rated power. I can get my Blueprint 1803 to bottom before clipping with frequencies below 18hz.

What do you have the Gain controls set to?

 

[David Giesbrecht]

When I had the receivers sub out calibrated to 0 db I had the gain dials at 12:00 o'clock.

PS: my receiver is a Marantz SR4200.

 

[Dan Hine]

When I had the receivers sub out calibrated to 0 db I had the gain dials at 12:00 o'clock.

Yikes! Turn those ALLLLLL the way up man. Then recalibrate.

 

[David Giesbrecht]

Let's see...20,000 - 60 = 19,940 sine waves. By your logic a single sine wave amplified with 10watts would be enough for say, a 90db speaker playing one tone. But to reproduce something like a symphony orchestra you would need 10watts x 19,940 waves which would be 199,400watts! Hell, even a 100th of that is right at 2000watts. When you stop and think about it David, it doesn't make sense at all.

A musical signal from a recording posseses bilions of sine waves actually and each instrument has a very complex sine wave of its own, its the combination of many sinewaves at a very low level that make a musical signal loud.

 

[David Giesbrecht]

Yikes! Turn those ALLLLLL the way up man. Then recalibrate.

I did, I turned the sub out on the receiver to -10 db and set the gains all the way up and theres no difference.

 

[Dan Hine]

Going by this theory your saying that a 100LB cannon ball would require no more energy to travel a certain distance than a 5LB cannon ball? that kinda goes against what I learned in physics class.

So basically you are still saying that to reproduce two single waves with 450watts a piece that you need a 900watt amp? Sorry David but that's crazy. I'm sorry my analogy wasn't good enough for you. Keep thinking what you want. But I would suggest you look up at Brian Tatnall's post again.

 

[David Giesbrecht]

heres a good point, you here all over the place the advantages of using a high pass filter on your main speakers to reduce the strain on an amplifier. (ie. cutting out the bottom octave gives you more power for the higher frequencies).

 

[Dan Hine]

its the combination of many sinewaves at a very low level that make a musical signal loud.

At a low level, eh? I guess we have different interpretations of what a low level is. During loud sections of a piece I'm producing about 103-110db all by myself.

Additionally, if a person has a 90db efficiency sub they'd need about 124watts to produce a tone at 110db. Which a lot of people here proclaim to reach. But certainly a movie has WAAAAY more than just one tone going on at any given moment. I hope they don't have more than 10 different tones going on at one time. That would require 1,240watts!

 

[David Giesbrecht]

At a low level, eh? I guess we have different interpretations of what a low level is. During loud sections of a piece I'm producing about 103-110db all by myself.

Yes thats right and you are producing thousands of different frequencies all at once, each frequency is taking up a very small amount of power from the amp to produce, but its the combination of all those different frequencies together that make the amp work hard and thus drive a loudspeaker to a high level.

 

[ThomasW]

The bass sounds extremly tight and smooth all the way up until the amp clips witch was rather dissapointing for me

Oh my, it's sounds like we have another case of "Bob Sorel Syndrome" at work here...... (hint; Bob's idea of 'acceptable' sound pressure levels for his HT woofers is an output level equal to that of a live rock concert).

 

[Jack Gilvey]

Example: If your running a signal generator @ 40 hz and its producing an average of 10 watts and you add a second tone @ 100 hz the amplifer will be producing a total of a 20 watt average because you are asking the generator to do twice the work.

More common sense?

 

[Shawn Solar]

David have you checked all connections. even if the bare wires are not touching high current can arc and short the coils and amp. Ask me how I know:frowning:

I just recently built a prototype sub. It is an av12 in a sealed enclosure and has a max power of 500watts. I didn't solder any connections in case I wasn't happy. I am running a ported 15 with 1000watts right now. So I hooked up the sealed 12" to my QSC amp and it sounded good but when I turned up what I thought was loud. The amp would clip yet no distortion and it wasn't that loud(or at least as loud as I thought it should be) I checked I wired it in series and check my trim setting and all that jazz. It wasn't until I took the sub out and looked at the connector plates I realized that the wires were just about touching. they were about 1/8" or less apart. I taped them up(I know) and tried it again. Success

Just brought it up cause it was so close to your experience.

 

[Brian Tatnall]

You understand that the load you put on the amplifier is largely dependent on your volume knob correct? Not on the frequency being played. When you turn up the volume you are changing the amplitude of the wave and thus the load it puts on the amp.

When look here:
http://www.eatel.net/~amptech/elecdisc/power.htm

Notice it is the volume or power knob that changes how much the speaker moves. (I'm not saying frequency doesn't matter. It does. I'm saying it doesn't matter as much when looking at just a subwoofer and the frequencies it plays.)

I think a lot of your problems come from an incorrect understanding concerning how waves on something like an oscilloscope translate into speaker movement.

You don't need to add another wave or anything like that you just need to turn up the volume.

Look here: http://www.eatel.net/~amptech/elecdisc/audoutex.htm

Play with the volume and you'll notice the oscilloscope shows a greater voltage demand.

The amplitude of the waveform changes. When it comes to power AMPLITUDE is what is most important. (Not forgetting that how long a wave is at it's maximum amplitude is also important. ex. Square Waves)

Your focusing on the LENGTH of the wave. Which is the wrong thing to focus on when thinking about the amount of power needed to create any sound. The LENGTH determines the frequency of the sound. Short is higher and longer is lower.

The LENGTH or FREQUENCY of the wave has LITTLE to do with the AMPLITUDE or (POWER NEEDED TO REPRODUCE THE SOUND).

For the picky people: Notice that when a wave is longer it has a bigger amplitude longer thus creating more demand, but this is trivial compared to the volume knob.

I'll write more later, I'm in the middle of moving into my college house.

 

[Dan Hine]

Why did you turn the receiver to -10db? Did you calibrate it to this or are you just guessing.

 

[Brian Tatnall]

You can have a 10hz tone require little to no power or require 10,000wrms.

You can have a 100khz tone require little to no power or require 10,000wrms.

When looking at power the wavelength matters little compared to the amplitude of the wave.

Running ANY wave when you have a greater amplitude more power is required. When there is no amplitude no power is required.

So what does this mean when combining waves?

Just like in a pool when waves collide they create crests and valleys. Sound does the same thing!!! When you combine waves some parts are amplified even more and some parts have a decrease in amplification. Like in the picture I showed of the two sine waves combined.

So theoritically it maybe possible to combine enough waves to and get a "HUGE amplitude". It is possible, but compared to anyones ability to change the volume on a reciever or amp the "HUGE amplitude" is trivial at best.

In addition just like on the ocean when waves collide it usually calms the water in music when sound waves collide it takes the power out of the waves usually.

I typed this all quickly and off the top of my head so if you have questions becuase I left things out let me know.

 

[David Giesbrecht]

More common sense?

I am wondering if you want to help me, or if you just want to be dead weight in this discussion. Maybe you should offer an inlightened opinion?

 

[Brian Tatnall]

So produce 3 tones at the same amplitude you'd need three times the power and to produce 4 tones at the same amplitude = 4 times the power, etc...

Well if you have one tone and triple the amplitude then yes you are going to need 3 times the power to produce it accurately. Same with 4, but does sound combine to do this? NO. Turning up the volume does though

Each tone requires a different amount of amplification because the length of time there is amplitude is different.

 

[Jack Gilvey]

I am wondering if you want to help me, or if you just want to be dead weight in this discussion. Maybe you should offer an inlightened opinion?

Actually, I'll leave that to Dan, he has more patience. I'm just getting a kick out of the fact that you really think you're right.