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Push that THANG'

Discussion in 'Amps and Cabs [BG]' started by basskid89, Feb 4, 2016.


  1. basskid89

    basskid89

    Dec 23, 2015
    Ok, so I have a Schroeder cab, 1000watts at 4 ohms, and I haven't been able to find a head to push it appropriately. It's got 2x10s and a 1x12" so im looking for something that will "push that THANG". I've used an ampeg SVT7PRO at 1000watts at 4 ohms, but only to find out that in order to get the full 1000watts you need to have 2 cabs at a total of 4 ohm load so it was really pushing it from one side at 600watts at 8 ohms . I have used an Aguilar tone hammer 500 the 500 watter at 4 ohms, I loved the eq sound of it but it was super weak at 250 at 8 ohms per side, in order to get the full 500watts I needed 2 speakers. I have also used a Crown XLS1500, and it actually blew my 12" inside the 2x10/1x12 3speaker cab into oblivion, because I had it bridged. Now after I have repaired it, I am now using the XLS1500 in stereo only in one channel at 500watts @ 4 ohms and it actually works way better. Because I'm getting the full 500 actual watts into the speaker at 4 ohms. It doesn't sound as weak as the other alternatives but it would be great to find that perfect amp/head to round out the bottom. Is there anything out there that is able to dish out, maybe not the complete capacity of the cab 1000watts at 4 ohms, but at least pretty dam close?? My fear is that if I under power the cab there will also be resistance causing the head/amp to fry.
     
    Last edited: Feb 4, 2016
  2. mbelue

    mbelue

    Dec 11, 2010
    No.
    What model of Schroeder exactly?

    If your cabinet is indeed 4 ohms you "get all the watts" out of any 4ohm minimum amp.
     
    Sartori likes this.
  3. basskid89

    basskid89

    Dec 23, 2015
    21012BMF
     
  4. Is your cab 4 ohm or 8 ohm?
     
  5. basskid89

    basskid89

    Dec 23, 2015
    4 ohm
     
  6. mbelue

    mbelue

    Dec 11, 2010
    Then you get "all the watts." No need for a second cabinet.

    What driver was your cabinet repaired with?
    Same as original?
     
  7. That being so, at no time was any amp running at 8 ohms. All of them were running at 4
     
    mbelue likes this.
  8. mbelue

    mbelue

    Dec 11, 2010
    I know that. Reread your original post.
    That jumbled post leads me to believe you need to read this.
     
    Sartori likes this.
  9. basskid89

    basskid89

    Dec 23, 2015
  10. My original post? "Is your cab 4 ohm or 8 ohm?"

    I think that the two of us are in total agreement. The OP seems to be a bit confused.
     
    mbelue likes this.
  11. If you have a 4 ohm cabinet the amplifier that that cabinet is plugged into will be running at 4ohms.

    You can not run 8 ohms into a 4 ohm cabinet.

    Your tone hammer for example was not running at 8 ohms when plugged into this cabinet.
     
    cjlembo and B-string like this.
  12. mbelue

    mbelue

    Dec 11, 2010
    Oops sorry for the confusion.
     
  13. mbelue

    mbelue

    Dec 11, 2010
    Your cabinet, if rated 4 ohms and has all the drivers recommended by the manufacturer, was running at 4ohms with any of those amps.
    The difference in sound/feel with these amps is a whole 'nother can of worms.

    The basic understanding of Ohms cabinets and amplifier ratings is really something you need to learn and pay close attention to.
    See the link i included above.
     
    Sartori and Old Garage-Bander like this.
  14. basskid89

    basskid89

    Dec 23, 2015
    I spoke to an Aguilar rep a while back and he told me when I ran my 4 ohm cab on one side of the tone hammer I was only getting 250 watts at 8 ohms from one side. And that if I wanted to get the full 500 watts I needed two 8 ohm speakers at 250 watts each. Like a pair of SL112's which are 250 watts at 8 ohms. According to your article, 8ohms/2speakers=4ohms total load.
     
  15. mbelue

    mbelue

    Dec 11, 2010
    Yes.
    A 4 ohm cabinet is also a 4 ohm load.

    Somehow either the Aguilar rep misunderstood you or you misunderstood him.
     
    Sartori, B-string and Downunderwonder like this.
  16. /\/\3phist0

    /\/\3phist0 Life: It's sexually transmitted and always fatal Supporting Member

    UNDERPOWERING SPEAKERS IS A MYTH. Cabinet under powering?
    search user bob lee (QSC)one example

    Cabinet under powering?


    "Ok, so I have a Schroeder cab, 1000watts at 4 ohms, and I haven't been able to find a head to push it appropriately. It's got 2x10s and a 1x12" so im looking for something that will "push that THANG". I've used an ampeg SVT7PRO at 1000watts at 4 ohms, but only to find out that in order to get the full 1000watts you need to have 2 cabs at a total of 4 ohm load so it was really pushing it from one side at 600watts at 8 ohms . I have used an Aguilar tone hammer 500 the 500 watter at 4 ohms, I loved the eq sound of it but it was super weak at 280 at 8 ohms per side, in order to get the full 500watts I needed 2 speakers. I have also used a Crown XLS1500, and it actually blew my 12" inside the 2x10/1x12 3speaker cab into oblivion, because I had it bridged. Now after I have repaired it, I am now using the XLS1500 in stereo only in one channel at 500watts @ 4 ohms and it actually works way better. Because I'm getting the full 500 actual watts into the speaker at 4 ohms. It doesn't sound as weak as the other alternatives but it would be great to find that perfect amp/head to round out the bottom. Is there anything out there that is able to dish out, maybe not the complete capacity of the cab 1000watts at 4 ohms, but at least pretty dam close?? My fear is that if I under power the cab there will also be resistance causing the head/amp to fry."


    4 ohms is 4 ohms REGARDLESS of the # of cabinets in use.

    the Aguilar tone hammer is a MONO amplifier, it has 2 speaker connections, it delivers 500 watts at 4ohms (see above) FWIW the SVT7 pro is a mono amp also, and will deliver 1Kwatts into a 4ohm load regardless of the # of cabinets (EX: 4x16 ohm cabinets, daisy chained / connected in parallel )

     
    cjlembo, Nev375, Sartori and 2 others like this.
  17. BurningSkies

    BurningSkies CRAZY BALDHEAD Supporting Member

    Feb 20, 2005
    Syracuse NY
    Endorsing artist: Dingwall Guitars
    This is why we can't have nice things.
     
  18. /\/\3phist0

    /\/\3phist0 Life: It's sexually transmitted and always fatal Supporting Member

    a site that may help you "get it"
    Can I underpower my speakers?Will clipping hurt them? - BillFitzmaurice.info
    Much to learn young padawan, you are not a jedi yet :D

    (listen to YODA AKA BFM)

    decided to just copy paste the content here (i hope Bill doesn't mind?)


    This excellent treatise explains why underpowering is a myth, one that unfortunately refuses to die:


    Amplifier clipping, and it's respective causes and effects, is perhaps one of the most misunderstood concepts amongst audio circles. There is a whirlwind of myths surrounding this topic that seems to exceed all other topics I have come across. Now is your chance to learn the truth about clipping.

    How Do Speakers Become Damaged

    There are only two ways that a speaker can be damaged, both of which occur from too much input power. 1. Mechanically 2. Thermally

    Every speaker has an excursion limit (often measured in mm), or how far the speaker can move forward or rearward before damage occurs. This is the mechanical limit of the speaker. This limit remains the same regardless of the use of the speaker, but the power required to reach this limit changes dependent on the enclosure. If you exceed this limit, the speaker will suffer mechanical damage, whether it's ripping your spider, bottoming out on the back plate, or any other mechanical damage. The second type, thermal damage, occurs when you exceed the thermal power handling limits of the voice coil itself. Voice coils are simple pieces of metal that will melt if too much power is applied. This limit is pretty much constant, ie. if a voice coil will be damaged at 1 kw, it will be damaged at 1kw regardless. There are two final myths to cover here. Despite the tireless efforts of some, there are still many people that believe that underpowering a speaker will damage it or that clipping will damage a speaker. Please remember that these last two thoughts are entirely UNTRUE! And now we will find out why.

    Where Does This Power Come From?

    Let's first understand the power potential of an amplifier when clipping. The power created is largely determined by the rail voltages. Let's compare two amps, each one connected to a 4 ohm speaker rated at 75 watts rms. Amp 1: 50 watt amp 50 Watt amp means this amp can cleanly deliver a sinewave of 50watts into a 4 ohm load. This means (Vrms)^2/4 = 50W Vrms = 14.14V Vpeak = Vrms*(1.414) Vpeak = 19.99V The rail voltages of this amp must be a bit higher, to prevent output stage distortion at this power level. In this case, the Rail voltage would have to be +/- 20 Volts. Amp 2: 75 watt amp (Vrms)^2/4 = 75W Vrms = 17.32V Vpeak = Vrms*(1.414) Vpeak = 24.49V In the example, the 75 watt amp is delivering 75 watts as it is not distorting at all. The 50 watt amp is in hard clipping, as and such, is delivering a fair bit more power. P = Vrms^2/R = (19.99V)^2/4 ohm = 100 watts. It is quite obvious that there is potential for an amplifier that is clipping to deliver substantially more power than you would expect. Keep in mind that this is only a way to determine peak voltage potential.

    Average Power

    Now we can get into how a speaker really gets hurt. The key issue is average power over time. Let's get to the nitty gritty. The first key is understanding Crest Factor.

    "Crest Factor" is the difference between the average level of the signal and its peak level. A pure sine wave has a "crest factor" of 3dB, meaning that it's peak level is 3dB higher than its average level. We all know that 3dB represents a difference in power by a factor of 2. Another way to look at it is that the peak power of the signal is twice that of its average level. If we were to play a sine wave on our 50 watt amplifier, just below its clipping level, the average power over time the speaker would need to dissipate is 25 watts. On the other hand, a square wave has a crest factor of 0dB. In other words, its average power and peak power levels are equal. Our same 50 watt amplifier playing a square wave into our speaker requires the speaker to dissipate 50 watts. Keep in mind that this refers to sine and square waves only. Music has a much higher crest factor. Most widely available recordings have a crest factor of approximately 10dB. Looking at this in terms of power, the peak power is 10 times greater than the average power. If we were to play one of these recordings with our 50 watt amplifier when not clipping, the speaker needs to dissipate a mere 5 watts of average power over time. When the amplifier begins clipping, the peak level/power does not increase. BUT, the average power DOES increase. If we were to turn the volume up 6dB higher than the clipping level of our recording, we have reduced our crest factor to 4dB. Guess what? We are now needing the speaker to dissipate 20watts. This is four times the average power and four times the heat when measured over time. As you can see here, it is not the distortion or the waveform or anything along those lines that is killing your speaker; there is simply more average power over time. However, if the average power of time is still below what your speaker can handle, it doesn't matter if it's clipping or not. At higher power levels, the fact that a clipped signal carries more average power over time can result in damage.

    DC in Clipping

    One of the most famous myths regarding clipping is that it produces DC. The assumption is made because of the flat tops and bottoms to a square wave. It's incorrect to think of a squarewave as made up of positive and negative dc components. The only way for a it to be DC would be if there was a non-zero average value over long periods of time. If the polarity changes at all within the time frame that you are looking at, it is simply not DC. What are these flat portions of the signal? It is simply a combination of the fundamental frequency and all of it's higher order harmonics in sine wave form. For example, if you were to play a 20hz tone while clipping, there would be the fundamental frequency (ie. 20hz) and the second (40hz), third (80hz), and 4th (160hz) order harmonics. The sum of these frequencies creates what appears as a squarewave. There are two ways to test this for yourself; one is quite easy, the other is a little more advanced. The first way is simple if you have a variable crossover and an oscilloscope handy. Pass a low frequency square wave. You will notice the square shape on the oscilloscope. Now turn your crossover's low pass filter on. Slowly lower the setting as you approach the fundamental frequency. You will notice the waveform on your oscilloscope slowly rounding off into a typical sinewave. Once you have reached the fundamental frequency, your oscilloscope will show a perfect sinewave. The second way is for your math guys (or for those who like to use Matlab). If you look in the frequency domain using a Fast Fourier Transform, you will see the fundamental frequency and its higher order harmonics only. There will be absolutely no DC present.

    Clipping and the still voice coil

    The final myth is that of the still voice coil. It is perhaps the most believed myth regarding clipping. The idea is that because of the square wave, the coil is not moving during the flat portions of the signal. This is simply not true for a variety of reasons. The speaker does exhibit mechanical damping and remains in constant motion. Assuming the same voltage and excursion xmax, the cooling at any given frequency will remain the same, whether the signal is clipped or unclipped.

    Summary

    To provide a final review of all that we have discussed on this topic, there are only two ways to damage a speaker: Mechanically and Thermally. The only way to do this is by applying too much input power in a given enclosure (mechanically) or too much average power over time (thermally). There is no DC in a clipped signal; the coil does not stand still; air passing over the coil (and thus cooling) is the same regardless of the waveform; and clipping is acceptable provided that the average power over time is lower than the speaker's limits. The next time you hear those famed words "your speakers died because of clipping", remember what you have learned, and above all, keep searching for the truth. It's out there somewhere.
     
    dazmond and Old Garage-Bander like this.
  19. BurningSkies

    BurningSkies CRAZY BALDHEAD Supporting Member

    Feb 20, 2005
    Syracuse NY
    Endorsing artist: Dingwall Guitars
    1) don't play around with amps that 'push' more than a kilowatt until you learn how the impedance ratings on cabs works.
    2) learn how the impedance ratings on cabs works
    3) don't buy a kilodollar cab until you understand how easy it will be to blow up
    4) don't use the phrase 'push that thang'.
    5) just don't.
     
  20. Yes, I think the OP needs to go to the bare basics, clear their mind of the mess of incorrect information and start again. This includes what impedance is and how to use it, and what they actually require from their gear.

    I think either there is a problem earlier in the chain causing a lack of volume, or the OP needs a lot more cab than what is being used.

    You may be surprised, but 45 watts of solid state power through the right speaker in a reasonably loud rock band is possible.
     

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