More power needed for Tempests? (1 Viewer)

[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).

I am waiting for an honest answer here.

please read this post entirely.

 

[Brian Tatnall]

I am not sure what you mean here?

When you turn the volume up you are sending a wave with greater and greater amplitude to the amplifier. When you turn the volume down your are sending a wave with less and less amplitude to the amplifier.

Thus your are changing the amount of current needed to accurately reproduce the wave (CLIPPING) and changing the amount of speaker movement needed to accurately reproduce the wave (BOTTOMING).

Compare 2 things.

1) The amplitude change when waves combine
2) The amplitude change when the volume knob is turned up or down.

1's change is trivial compared to the amount 2 can change.

When you adjust any of the knobs on your reciever ask yourself this question.

What am I doing to the wave?

Once you can answer that question all your other questions will stop mattering for the most part.

 

[David Giesbrecht]

1's change is trivial compared to the amount 2 can change.

yes it is, but in the end it does have a large effect on final output of the amp if your volume knob is at a fixed position.

 

[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).

still looking

 

[Dan Hine]

I know what the subs bottoming out souds like, this is easy to accomplish when driving them with pure tones but impossible when trying to play back a movie soundtrack which contains plenty of deep bass.

It's impossible to bottom a sub when playing back soundtracks? Hardly! It happens a lot. Look it up.

 

[Brian Tatnall]

I said it takes twice the power to produce two sine waves of equal amplitude. I understand that all sinewaves in a musical signal are not the same amplitude but even at that they do use up some power whitch then becomes unavalible for others.

This is your PROBLEM. Waves COMBINE. THEY COMBINE. I'll say it again WAVES COMBINE.

Your amp and speaker do not see each sound individually. They see one amplitude at any point in time. ONLY ONE. If you feed an amp or speaker two then it will create ONE anyway. ONE and ONLY ONE.

Just to give your example a little visualization when compared to reality.

How can one tone take up the power that another tone needs when they have actually combined and are ONE tone.

The don't give and take from one another. They COMBINE.

 

[Brian Tatnall]

yes it is, but in the end it does have a large effect on final output of the amp if your volume knob is at a fixed position.

If your volume knob is at a fixed position then the only thing that is changing when you change CD's is the original recording volume.

I don't see what your trying to say here.

Original recording volumens are normalized to keep all the amplitudes within a certain range.

 

[Brian Tatnall]

Look at the the graphs. Often it is the smallest thing that is most important.

You have amplitude on the y-axis and time on the x-axis.

One amplitude at any point in time.

How can there be sharing, giving, taking,if there is only ONE amplitude? Waves aren't buddies

 

[Scott Simonian]

I calibrate my subs to the level I prefer, But THIS IS NOT THE ISSUE!

Um...

Yeah, I used to do that I ran into trouble. It was more of problem before I got my Tempest, really. Trying to squeeze out lower frequencies from my DefTech was hard on the sub. The same happened when I got my Tempest finished. I had my levels up a bit too high. I found that the tempest would struggle on the big time bass moments in our favorite reference films.

The gain on the plate amp is about 1/4 of the way and the level on my receiver is about -3db. I love how the sub sounds. I isnt calling attention to itself like my DefTech had to.

Maybe you should pick up a copy of Avia or D:VE, calibrate, then talk to us again.

It really sounds like you just have them up really high but I dont know for sure. I wish I could drop by a listen for myself. But since I cant and that everyone else is more experienced than me.

Listen to these guys, they know what they are talking about.

 

[Shawn Solar]

The bigger issue here is how can you put 800-900watts to a tempest when max excursion occurs with 250watts or less. You must be clipping something other than the output. 900watts MAY not fry a tempest thermally but mechanically there is no question. It must be the input voltage being clipped at the reciever and a improper signal to the amp or the amp just cannot handle the input signal. Or like I said earlier, there is a short across a voicecoil due to wires being too close.

And since you know that your tempest is still working you know you are not drawing 900watts. Also if you want to see what kind of load the sub is seeing put a multimetre. Then download adire's lscpad and they give you watts and volts for speaker input power. Input the voltage reading to see the corrosponding wattage. You will then be able to see Excursion and what your woofer is doing.

Or unplug the sub and see if the amp still clips that will confirm whether its the signal or something else.

About sinewaves, If all waves were seperatly amplified and amplifaction doubled for every sinewave played at the same time how would the subs cone move. would it play every wave seperatley at the same time? would it move say 20 cycles/second and then 30cycles/second at the same time. How could it? Would we here both tones or a combination of the two.

 

[David Giesbrecht]

It's impossible to bottom a sub when playing back soundtracks? Hardly! It happens a lot. Look it up.

Sorry if you misunderstood me what I meant was I have not been able to bottom them with this amp and my setup.

 

[David Giesbrecht]

SURF works with this amp to keep the headroom around down deep, and to keep the bass natural and tight.

This was taken right off of Adire Audios web site. Note The emphises on keeping headroom where it needs to be.

 

[Shawn Solar]

Thats because subs amps only play bass(obviously) But sub amps are fullrange from my understanding. they just have a high pass built in. Bass=more power moslty stems from having to move a heavy, large surface area. Magnet structures are larger therefore higher electromagnetic field. So electrically speaking are like a v8 engine vs a 4 banger. also subs tend to have high moving mass and are less sensitive so more power for higher spl.

A 1000watt pro amp usually provides the same power across its full range. At least if its any good. The QSC is a very decent amp.

 

[Michael R Price]

David, you may be overloading the input of the QSC amplifier because its gain is set too low and your receiver's subwoofer output is set too high. This will cause the clip indicator to light (and might cause the sound to compress or distort) even when the amplifier is not delivering near its rated output. I apologize if I missed something and you have ruled this out as the source of your problem. And by the way, it is good to see some other kids playing around with this stuff!

You can look at a wave either as a single function of amplitude versus time, or of the sum of an infinite number of sine waves. But the key thing is that the amplitude of each frequency component is much smaller than the overall frequency of a wave. A movie sound effect signal coming from your receiver may have an overall amplitude of 4 volts, and if you divide it up by 1/3-octave components, the 20Hz component might have an amplitude of, say, a half volt. So if you took a bunch of sine waves at full amplitude and added them together, you would indeed have a wave with the sum of all those amplitudes. But in real signals each frequency component contributes a small bit to the amplitude of the final signal.

 

[David Giesbrecht]

David, you may be overloading the input of the QSC amplifier because its gain is set too low and your receiver's subwoofer output is set too high.

This has been covered and I don't have any room to adjust any more, the receivers sub out is set at minimum (-10db)

 

[David Giesbrecht]

And by the way, it is good to see some other kids playing around with this stuff!

This is pretty cool I didn't think there was anybody else here in my age group. Nice to meet you mike!

 

[David Giesbrecht]

It really sounds like you just have them up really high but I dont know for sure.

I don't think so I have had many people come to my house to watch movies and they always comment on how reserved I am with their output.

 

[Shawn Solar]

Dave Ihave had a passion since I was 15yrs old and I'm 22 now. It is also a part of my career as I'm trying to do more and more installs(I'm a phone, cable and alarm tech now)

I still have it hard to believe you are clipping the amp and not some sort of protection circuit. I have also had to change a bad connector once. The rca to 1/4" miniplug fell apart. I would try switching out wires and disconnect All wires and rewire it from scratch. I can not tell you how many times I've missed my own mistakes. Re-hooking it up from scratch sometimes corrects the problems you forget/missed to see. other than that I would have to say the amplifier is defective and is tripping the protection circuit(which has also happened when there is abad cap or something)

 

[Pete Mazz]

You should always leave the gain control of a pro amp at full. These do not work like volume controls and boost the input, they only attenuate it by turning down the control. Then use the sub level setting of your processor to calibrate. If you're serious about your sound, it's well worth the ~$30 or so from Rat Shak.

And, just to make sure, when you say the subs never bottom out on movies, you are talking about a DVD and not watching a movie on cable or something, correct?

Pete

 

[David Giesbrecht]

You should always leave the gain control of a pro amp at full.

Its at full and the sub out on my receiver is at -10 db so if I left the gains on my amp at full I can't turn the subs down any more than what they are.

Shawn, I will definetly take your suggestion to heart.
I will try reconnecting everything tommorrow and see if I missed anything.
Can I pickup any kind of power meter to connect to my amp to see if it is actually putting out it's max output?