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Hi guys,

so recently i build the Dayton Ultimax 12 with the fitting sealed enclosure from partsexpress. I wired the subwoofer correctly in series so that i got a 4ohm load.

Ive got a cambridge audio cxa81 and from my sub out i go to the crown. The cambridge doesnt have any options for the sub out so i had to set the dsp on my crown.

I hooked it up to my Crown XLS1502 in bridged mode, set the LPF at around 80HZ, put the input sensitivity to high (0.775V). I hooked it up via cinch cables.

And now im not quite sure what is the problem here. Since the Crown is rated at 1550W in bridged 4 Ohm the amp is clipping way before what the sub could handle.

Normally the sub would like explode way before the amp goes into clipping right?

Im not sure if i just did expect more from a 12 inch sub or maybe its just the amplifier ?

It could also be to my room, since i didnt got a dsp yet. Because some tracks i play, the bass gets pretty loud. But still, it feels like the crown doesnt produce any near between 1550W at 4 ohm.
 

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I believe what you have here is a sensitivity mismatch issue.

If the amp is clipping way before the
sub is being pushed to its limits then I believe it’s not the amps output stage that’s clipping but more the crowns input stage that’s clipping.

So you have set the input sensitivity to high

This doesn’t mean it expects a high signal from the pre amp. (I’m guessing here) but rather means that the crown is set he be very sensitive to input. Hence too much input from pre amp clipping the crowns inputs

Try setting the sensitivity to low. Thus the crown expects a high signal and then turn the gain up more.

It doesn’t matter if the gain is near full. It’s about a balance of how much the amp is boosting the signal coming from the pre out.

I hope I’m not completely off the boil and expect someone be will say if I am.

But I have a diy alpine 15 type R with a Inuke 6000 amp not bridged. (1000 rms in to 8ohms approx) and I can get the amp to clip but not without the woofer being on the edge. At past reference levels bringing the house down literally.

And I have 25mm or xmax to play with too.


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I believe what you have here is a sensitivity mismatch issue.

If the amp is clipping way before the
sub is being pushed to its limits then I believe it’s not the amps output stage that’s clipping but more the crowns input stage that’s clipping.

So you have set the input sensitivity to high

This doesn’t mean it expects a high signal from the pre amp. (I’m guessing here) but rather means that the crown is set he be very sensitive to input. Hence too much input from pre amp clipping the crowns inputs

Try setting the sensitivity to low. Thus the crown expects a high signal and then turn the gain up more.

It doesn’t matter if the gain is near full. It’s about a balance of how much the amp is boosting the signal coming from the pre out.

I hope I’m not completely off the boil and expect someone be will say if I am.

But I have a diy alpine 15 type R with a Inuke 6000 amp not bridged. (1000 rms in to 8ohms approx) and I can get the amp to clip but not without the woofer being on the edge. At past reference levels bringing the house down literally.

And I have 25mm or xmax to play with too.


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I already tried that. Then i just have to turn my cambridge louder to get to the same levels, but it still ends up in clipping.
 

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What levels do you have the gain set at on the crown?

What frequencies are you playing and what’s the Q of the box you built.?

It Could be possible I suppose that at 50 to 80 hz, the Dayton can take that amount of power without running in to trouble.

You Know these things are hard to help with unless you’re there or have extensive experience . I have a bit. Not as much as many.

Could your room be an issue. In that your positioned in a null in the room? So it
Seems like the sun is produced low bass.

Maybe would be a good idea to get a mic and take some measurements


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Yeah so the box appears to be designed to a QTC of 0.707.

That’s what gives the flattest response in bass.

Basically the bigger the box, the lower the bass will go but at the sacrifice of pure output.

A sealed box should protect the woofer
From bottoming out. Due to the volume of air inside acting like a spring.

But if you Make the box too big then it won’t be able to protect the d and ver as well and you would need less watts to bottom the sub.

You Don’t have that issue and at certain frequencies I expect the sun could take some serious power before it ran in to any trouble..

That being said, I’m still unsure that you would be seeing clip lights unless it was seriously loud..

Are you sure there are not any digital limiters set in the crown that limits wattage to the sub?


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Yeah so the box appears to be designed to a QTC of 0.707.

That’s what gives the flattest response in bass.

Basically the bigger the box, the lower the bass will go but at the sacrifice of pure output.

A sealed box should protect the woofer
From bottoming out. Due to the volume of air inside acting like a spring.

But if you Make the box too big then it won’t be able to protect the d and ver as well and you would need less watts to bottom the sub.

You Don’t have that issue and at certain frequencies I expect the sun could take some serious power before it ran in to any trouble..

That being said, I’m still unsure that you would be seeing clip lights unless it was seriously loud..

Are you sure there are not any digital limiters set in the crown that limits wattage to the sub?


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Ok thanks for the explanation.

What do you mean by the "sun" could take some serious power?

Yeah it can get loud when really near clipping depending on the track. But if it is near clipping the amp should produce anywhere near 1550W , and my sub can only handle 600W. So normally from my knowledge the sub should like explode or i dont know.

There arent any digital limiters from what i know. I also factory reseted it. The only thing i set is a crossover because the cambridge sub out isnt crossed over.

Im quite unsure, because it varies so much from track to track. The best thing to do would be taking measurements and integrating the subs with my mains with a minidsp. And then look again.

Ive also got no reference how loud a 12 inch sub with 600W ( 86.7db/w/1m ) can be or should sound.
 

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Yeah im totally sure. I did the same thing as the guy from parts express on youtube. Made a bridge from + to - and hooked the other + and - to the speaker terminal, so it should be in series.
Have a Picture of what you did?

Want to make sure you connected the + of coil A to the - of Coil B to be series instead of connecting the + to the - of the same coil and only using the other coil.
 

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Right so to clarify a few things.

When I say sun. I mean sub. My phone doesn’t like sub so changes it all the time and annoys the hell out of me.

Next thing to consider is that the xls1502 from reading around, doesn’t produce 1500w rms in to a 4ohm load.

I think it’s probably nearer to 900rms. In actual honesty. Don’t worry about this, they never do. Doesn’t mean it’s a bad amp.

Next thing to consider is your sub can actually take more than the 600W suggested.

The 600w figure is dependant on many factors. For instance, They have probably tested sending 600W continuous power to the sub and also at a certain room temperature on a certain size enclosure with limited air flow.

In real life situations (music with a heavy baseline) the sub will hit and then 1/4 of a second later hit again. There is a time where the sub rests where no power is going to it. And there are times when due to the dynamic range of the track, it may be not getting 600w. It could also at certain peaks get 1200w.

As long as it’s not for a continuous period, then the voice coils won’t overheat and melt. as long as your not playing full power 20hz tones for a long time.

Again, the enclosure will protect the woofer from over excursion within reason. Unlike ported boxes. Where you need to be careful.

Next thing to bear in mind is the woofer sensitivity of around 86db per 1W at 1m distance.

That’s not a very sensitive driver. It needs more watts to go loud. And obviously I assume your sat at a greater distance than 1m so that’s even more wattage to get to loud levels.

This doesn’t mean it’s a bad driver, it means it’s designed for a certain task. Mainly home theatre. The heavier the driver and more Xmax it has (linear throw), the more wattage it needs to make it move.

Every 10db is double loudness.
It takes double the wattage to increase loudness by 3db. And I think loudness gets less by 3db at 2 meter and then 6db at 4 meters (might be wrong with that but near enough)

Take another 12” sub with 99db sensitivity and for 1W it’s over twice as loud. More suited to music playback but will be lighter and not suited to earthquakes at 20 - 30hz. There are captions but more expensive and not really suited to this discussion.

Most music only drops to 35hz
anyway. And then output of the more sensitive sub will be more in the upper frequencies overall.

I know it doesn’t directly solve yourself issue, but it may help you understand a few more things

Best thing to do is level match mains to sub . Get a minidsp, a umik1 mic and do some experimenting.


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Discussion Starter #12
Have a Picture of what you did?

Want to make sure you connected the + of coil A to the - of Coil B to be series instead of connecting the + to the - of the same coil and only using the other coil.
Right so to clarify a few things.

When I say sun. I mean sub. My phone doesn’t like sub so changes it all the time and annoys the hell out of me.

Next thing to consider is that the xls1502 from reading around, doesn’t produce 1500w rms in to a 4ohm load.

I think it’s probably nearer to 900rms. In actual honesty. Don’t worry about this, they never do. Doesn’t mean it’s a bad amp.

Next thing to consider is your sub can actually take more than the 600W suggested.

The 600w figure is dependant on many factors. For instance, They have probably tested sending 600W continuous power to the sub and also at a certain room temperature on a certain size enclosure with limited air flow.

In real life situations (music with a heavy baseline) the sub will hit and then 1/4 of a second later hit again. There is a time where the sub rests where no power is going to it. And there are times when due to the dynamic range of the track, it may be not getting 600w. It could also at certain peaks get 1200w.

As long as it’s not for a continuous period, then the voice coils won’t overheat and melt. as long as your not playing full power 20hz tones for a long time.

Again, the enclosure will protect the woofer from over excursion within reason. Unlike ported boxes. Where you need to be careful.

Next thing to bear in mind is the woofer sensitivity of around 86db per 1W at 1m distance.

That’s not a very sensitive driver. It needs more watts to go loud. And obviously I assume your sat at a greater distance than 1m so that’s even more wattage to get to loud levels.

This doesn’t mean it’s a bad driver, it means it’s designed for a certain task. Mainly home theatre. The heavier the driver and more Xmax it has (linear throw), the more wattage it needs to make it move.

Every 10db is double loudness.
It takes double the wattage to increase loudness by 3db. And I think loudness gets less by 3db at 2 meter and then 6db at 4 meters (might be wrong with that but near enough)

Take another 12” sub with 99db sensitivity and for 1W it’s over twice as loud. More suited to music playback but will be lighter and not suited to earthquakes at 20 - 30hz. There are captions but more expensive and not really suited to this discussion.

Most music only drops to 35hz
anyway. And then output of the more sensitive sub will be more in the upper frequencies overall.

I know it doesn’t directly solve yourself issue, but it may help you understand a few more things

Best thing to do is level match mains to sub . Get a minidsp, a umik1 mic and do some experimenting.


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Ahh ok right got you man.

Ok really appreciate your knowledge thanks man.

My main application would be music in general. So for the next build in the future should i look for a subwoofer that has a better sensitivity? and could you give me a little bit of recommendation maybe?

I will inform you guys in the near future how it went out.
 

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Don’t read in to what I say too much. The sub when setup properly should still bang pretty hard.

But if I were looking for a music sub and no movies I would personally look at something more akin to a pro audio driver.

Not sure off top of head but I would look at b&c speakers. Considered one of the best. They do a good blend of high sensitivity and decent Xmax drivers that take serious power

I’m sure you Will be happy once you have considered the blend between mains, crossovers etc.

Take serious consideration to listening position and speaker / sub positions. (Microphone really helps here)

2 subs are better than one lol.

Long shot but make sure you
Have wired the sub up to the bridge terminals of the crown so you
Def running bridged


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When you play what should be deep loud bass is the driver moving around an inch or so peak to peak. I use 6 um18 subs and 16kw of amplification and it takes a good kick in the shorts to get them moving.
 

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Discussion Starter #15
Don’t read in to what I say too much. The sub when setup properly should still bang pretty hard.

But if I were looking for a music sub and no movies I would personally look at something more akin to a pro audio driver.

Not sure off top of head but I would look at b&c speakers. Considered one of the best. They do a good blend of high sensitivity and decent Xmax drivers that take serious power

I’m sure you Will be happy once you have considered the blend between mains, crossovers etc.

Take serious consideration to listening position and speaker / sub positions. (Microphone really helps here)

2 subs are better than one lol.

Long shot but make sure you
Have wired the sub up to the bridge terminals of the crown so you
Def running bridged


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Ok yeah got it.

Yeah the second sub was already planned. At first i wasnt sure if i should go with a single 15 or 18 inch or dual 12 inch subs. But from what i read the dual 12 should sound better with music.

Yeah im quite sure i did it correct.
 

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When you play what should be deep loud bass is the driver moving around an inch or so peak to peak. I use 6 um18 subs and 16kw of amplification and it takes a good kick in the shorts to get them moving.
That would end in divorce for me I’m afraid. Lol m.fair play though.


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I will try not to be redundant. Trojantrow pretty much delivered what came to my mind.

I will contribute....

Yes, REW with a MiniDSP) microphone is a great tool. Everybody should have one. It saves SO much time helping you to nail down what you are hearing, or not hearing, to help you address it. If you're getting nulls due to standing waves, at some frequencies, what you're hearing is less than the driver is actually putting out, in which case, a change in location may be warranted, or at the minimum, maybe doing an audit on any 'correction' to perhaps override its attempt to 'correct' the room by dumping power into a frequency that can't be 'fixed'.

A basic volt meter can help you both level match, as well as determine actual signal levels, at the input of the amplifier, and the output of the amplifier. It does not have to be expensive to be good enough. If you want to get a Fluke, I wouldn't tell you not to, but most of them will measure within the subwoofer frequency range just fine.

I would suggest, though, that you start low, do it methodically, when you have no other distractions, because to measure it requires a continuous tone for several seconds, and because it is not peaking, it also means it is not NOT peaking. I.e., you can fry things, especially your subwoofer. At higher frequencies especially, you can burn out the voice coil without mechanically stressing the motor assembly, exceeding excursion, etc. Point being, you could be on your way to smoking your driver, and it sounds relatively fine until it suddenly goes quiet.

If you know your voltage, and you know the impedance at that frequency, you can determine power (or at least apparent power). If you know the phase angle of the load, you can determine real power.

Watts=VoltageXAmperage*Cos(PhaseAngle).

If you measure the voltage, and you know the impedance, you don't have to measure the current, you can calculate it with Ohm's law, E=IR (or V=AR / Voltage = Amps*Ohms), solve for Amps, Amps=Volts/Ohms, and then plug it into the power calculation to get

Watts=(Voltage^2/Ohms)*Cos(PhaseAngle)

Or for the sake of what we care about, what the amplifier is 'putting out', just don't worry about cos(phaseangle) and

Watts=V^2/Ohms

If you really want to know to be accurate, you should measure the current too, because the impedance will go up as the voice coil heats and the resistance goes up, and/or for that matter, measure the impedance plot immediately after to see what it is doing when the coil is heated to the temperature it gets to at that output level, but then again, the heat it would get when you were measuring it continuously would not be the heat it was getting if it was dynamic so...

I'm really spinning off base.

Point being, you can measure the voltage level at the input, at a certain gain setting, and see how that tracks with your entire range of operation.

For instance, if your 'system' volume is at -6 dB, and your maximum range is 0 dB (reference level), and you run a signal in REW via a digital connection of some sort at -6 dBFS (6 dB below maximum signal you can record on the source), then you are - 12dB from the maximum possible voltage output level (0 dBFS, 0 dB system gain).

Note, I am assuming no EQ or filters involved, so whatever they do is compounded. That is pretty close (but not exactly) 1/16th power level, and 1/4 of the voltage level of maximum output, and it is easy to multiply by 4.

So, on the input of the amplifier, you want to know your input sensitivity of the amplifier (signal level in volts that drives the amplifier to full output). If it has gain adjustments, that level is... adjustable, in which case you would like to run it so that the output of your preamplifier is near (but not beyond) it's maximum output. Keep in mind, though, that if you've got EQ involved, this level will measured will change with frequency, so either measure it at the frequency of maximum boost, or run it low by whatever amount that maximum boost it. But this is really a matter of signal to noise ratio, so long as the signal can get high enough.

On the amplifier output, you don't really set that, but if you measure the voltage at one gain setting, since amplifiers are pretty linear (or they should be), you know the output level well enough at all levels until you exceed their output capabilities. So, if you measure the amplifier voltage and it is swinging 10 volts (which should be safe to run continuously into that driver, and you are calculating estimated power at a 4 ohm 'nominal' load, which is good enough for us, probably,


Watts=V^2/Ohms
Watts=10^2/4=100/4=25 watts * 4 ohms, 12.5 watts at 8 ohms, 50 watts @ 2 ohms, etc.
Every 6 dB of gain adjustment is about twice the voltage, so if you wanted to run a 6 dB table from there (roughly)


VoltageOhmsPower
5​
4​
6.25​
10​
4​
25​
20​
4​
100​
40​
4​
400​
80​
4​
1600​


Hopefully that's useful, and not just a plain mess. If I screwed anything up, you can have a refund of the consulting fee :)
 

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Hi guys,

so recently i build the Dayton Ultimax 12 with the fitting sealed enclosure from partsexpress. I wired the subwoofer correctly in series so that i got a 4ohm load.

Ive got a cambridge audio cxa81 and from my sub out i go to the crown. The cambridge doesnt have any options for the sub out so i had to set the dsp on my crown.

I hooked it up to my Crown XLS1502 in bridged mode, set the LPF at around 80HZ, put the input sensitivity to high (0.775V). I hooked it up via cinch cables.

And now im not quite sure what is the problem here. Since the Crown is rated at 1550W in bridged 4 Ohm the amp is clipping way before what the sub could handle.

Normally the sub would like explode way before the amp goes into clipping right?

Im not sure if i just did expect more from a 12 inch sub or maybe its just the amplifier ?

It could also be to my room, since i didnt got a dsp yet. Because some tracks i play, the bass gets pretty loud. But still, it feels like the crown doesnt produce any near between 1550W at 4 ohm.
These may be stupid questions, so forgive me, but do you have the amp set to "bridged" in the settings menu? Do both channel lights light up when it's running? Are you using Channel 1 to set the gain and not 2?
 

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Discussion Starter #19
These may be stupid questions, so forgive me, but do you have the amp set to "bridged" in the settings menu? Do both channel lights light up when it's running? Are you using Channel 1 to set the gain and not 2?
Yes, yes and yes
 

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I will try not to be redundant. Trojantrow pretty much delivered what came to my mind.

I will contribute....

Yes, REW with a MiniDSP) microphone is a great tool. Everybody should have one. It saves SO much time helping you to nail down what you are hearing, or not hearing, to help you address it. If you're getting nulls due to standing waves, at some frequencies, what you're hearing is less than the driver is actually putting out, in which case, a change in location may be warranted, or at the minimum, maybe doing an audit on any 'correction' to perhaps override its attempt to 'correct' the room by dumping power into a frequency that can't be 'fixed'.

A basic volt meter can help you both level match, as well as determine actual signal levels, at the input of the amplifier, and the output of the amplifier. It does not have to be expensive to be good enough. If you want to get a Fluke, I wouldn't tell you not to, but most of them will measure within the subwoofer frequency range just fine.

I would suggest, though, that you start low, do it methodically, when you have no other distractions, because to measure it requires a continuous tone for several seconds, and because it is not peaking, it also means it is not NOT peaking. I.e., you can fry things, especially your subwoofer. At higher frequencies especially, you can burn out the voice coil without mechanically stressing the motor assembly, exceeding excursion, etc. Point being, you could be on your way to smoking your driver, and it sounds relatively fine until it suddenly goes quiet.

If you know your voltage, and you know the impedance at that frequency, you can determine power (or at least apparent power). If you know the phase angle of the load, you can determine real power.

Watts=VoltageXAmperage*Cos(PhaseAngle).

If you measure the voltage, and you know the impedance, you don't have to measure the current, you can calculate it with Ohm's law, E=IR (or V=AR / Voltage = Amps*Ohms), solve for Amps, Amps=Volts/Ohms, and then plug it into the power calculation to get

Watts=(Voltage^2/Ohms)*Cos(PhaseAngle)

Or for the sake of what we care about, what the amplifier is 'putting out', just don't worry about cos(phaseangle) and

Watts=V^2/Ohms

If you really want to know to be accurate, you should measure the current too, because the impedance will go up as the voice coil heats and the resistance goes up, and/or for that matter, measure the impedance plot immediately after to see what it is doing when the coil is heated to the temperature it gets to at that output level, but then again, the heat it would get when you were measuring it continuously would not be the heat it was getting if it was dynamic so...

I'm really spinning off base.

Point being, you can measure the voltage level at the input, at a certain gain setting, and see how that tracks with your entire range of operation.

For instance, if your 'system' volume is at -6 dB, and your maximum range is 0 dB (reference level), and you run a signal in REW via a digital connection of some sort at -6 dBFS (6 dB below maximum signal you can record on the source), then you are - 12dB from the maximum possible voltage output level (0 dBFS, 0 dB system gain).

Note, I am assuming no EQ or filters involved, so whatever they do is compounded. That is pretty close (but not exactly) 1/16th power level, and 1/4 of the voltage level of maximum output, and it is easy to multiply by 4.

So, on the input of the amplifier, you want to know your input sensitivity of the amplifier (signal level in volts that drives the amplifier to full output). If it has gain adjustments, that level is... adjustable, in which case you would like to run it so that the output of your preamplifier is near (but not beyond) it's maximum output. Keep in mind, though, that if you've got EQ involved, this level will measured will change with frequency, so either measure it at the frequency of maximum boost, or run it low by whatever amount that maximum boost it. But this is really a matter of signal to noise ratio, so long as the signal can get high enough.

On the amplifier output, you don't really set that, but if you measure the voltage at one gain setting, since amplifiers are pretty linear (or they should be), you know the output level well enough at all levels until you exceed their output capabilities. So, if you measure the amplifier voltage and it is swinging 10 volts (which should be safe to run continuously into that driver, and you are calculating estimated power at a 4 ohm 'nominal' load, which is good enough for us, probably,


Watts=V^2/Ohms
Watts=10^2/4=100/4=25 watts * 4 ohms, 12.5 watts at 8 ohms, 50 watts @ 2 ohms, etc.
Every 6 dB of gain adjustment is about twice the voltage, so if you wanted to run a 6 dB table from there (roughly)


VoltageOhmsPower
5​
4​
6.25​
10​
4​
25​
20​
4​
100​
40​
4​
400​
80​
4​
1600​


Hopefully that's useful, and not just a plain mess. If I screwed anything up, you can have a refund of the consulting fee :)
It will take a while to understand what you wrote, but my father is electrician and we will figure it out together.
But i also read on other forums that the rated 1550W at 4 ohms is definietly not RMS. The amp runs better at 8 ohm loads.

Since i have an integrated amplifier with a sub out i cant pull it up to 100% because then my speakers would die.

But i tried plugging them off, turned the Cambridge to max level and it produces a lot more bass
 
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