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First, please tell me you aren't going to bring up that silly and wanton destruction of drivers at the GTG to defend your position here?

 

Of course, although we agree you can't name enough to occupy all of the fingers on one hand, there exist a few scenes with sine wave content in soundtracks that are demanding on a system that has no electronic protection against such content, which is why anyone with half a brain should always ease into a new soundtrack with ANY system, regardless of test results data or published specifications... especially when someone with half a brain is yelling to the guy with the remote in his hand to "BACK OFF", three drivers into the childishly silly demo.

 

Yes I am. I stand by the comment I made in the previous post. The content simply wasn't very demanding when the SP2-8K was used. The first night it was not Lone Survivor, it was some bass music that Brandon had that was being played back very loudly for an extended period. Some people push their systems hard and this type of content with extended synthetic bass tones is out there. To not plan for a difficult scenario for the system employed is foolish IMO. Call it childish or idiotic or whatever but people who buy bass systems usually like loud bass and will push their systems hard at some point. It should be planned for without resorting to having to keep an eye on everything that is played individually. In the case of burning a coil up you likely won't even notice until you start to smell burning adhesive at which point it may be too late already.

 

I've seen that Carver quote many times before and others from Tom Danley and Don Keele to the same effect. I agree with it completely. That does not mean that it is going to work out well when you have the 1500 watt rated amp on a driver rated at 150w program that bottoms out mechanically with 400w in the design being used. That is not the intention of the comments by these guys. It is implied that the other half of the equation is needed which is a speaker system that can safely make use of all that amplifier capability.

 

You're suggesting, and have suggested the same in the past, that the max excursion reached at 10 Hz with sine wave input in your all but irrelevant to playback of soundtrack content ground plane tests is the maximum a driver in a box can handle. If I'm reading you incorrectly on this point, please help me out with this.

 

But then, you devote a paragraph to emphasize my point, which is that real content is dynamic, more specifically, transient in nature and extremely wide bandwidth (in the case of a subwoofer, the transients are full bandwidth) and thus requires much more amplifier output capability than a 10 Hz sine wave will require to drive the system to max excursion. No, it's not as difficult on a driver from a standpoint of excursion. Yes, of course it's more demanding on the amplifier... which is my point.

 

Instead of that preachy paragraph, can you tell us, in the case of the hulk scene being cited, exactly how much more voltage is required? (because I obviously disagree with your contention that "no real power is required" to reproduce transients in the subwoofer band).

 

Yes I do and did. If I'm designing a system using a driver I've tested I will use the data I've pulled from it to make informed decisions on how much amplifier is a good match in the application and enclosure alignment it will be used in. The DIY tests are not about a finished system people should copy. They are about the driver performance and give information about the driver that can be used to develop a finished system for the app at hand using that driver. Personally I would not use any more amplifier than one that can indefinitely produce the amount of voltage applied during the loudest long term sine wave sweep in the sealed enclosure. This is very often close to a thermal limit for the coil. Peak voltage capability applied for the burst tests I'd also consider. If this is done the system should be reasonably safe from the coil burning up barring something with a truly strenuous duty cycle and the driver can use all or nearly all of its useful displacement but cannot be mechanically endangered. This type of system can be beat on quite severely and it will be safe no matter the signal applied to it in the majority of cases.

 

An entire host of unknown factors would need to be known to provide the "voltage required" for the Hulk scene at your place with your setup. It's off subject anyway.

 

Correct...Transient, dynamic, wide band content is not strenuous on drivers comparatively. I never made the comment that "no real power is required" for transients. What I said was that there is no real long term power applied to the drivers with this type of signal, a completely different comment which I stand by.

 

I would never design a bass system to use an amplifier which could produce maximum available cone excursion from the drivers using a wide bandwidth, complex signal. First off what wide bandwidth, complex signal? Secondly if a focused single frequency signal with the same voltage ever comes along, at a frequency that produces peak driver excursion, it is likely to bottom the driver out with bad result.

 

Your original comment that started this discussion, which is below, was about needing a K20 to power a single HS-24. Now granted I assume that you were trying to point out that to get the full 18dB on top of the data posted here you would need a full amp for each driver. That is true but only above 50Hz and only with very short duration burst signals. Below 30Hz a single K20 will happily drive 4 of the 24's to their limits quite comfortably. This was the whole start of the discussion which has now wandered off into the weeds a bit.

 

What does two HST-15's on half the power have to do with anything? Your original comment basically said that you will need a bridged A14K to run a SINGLE HST-15 or any other driver for that matter...The HST-15 has the same motor, same coil, same amount of excursion potential as the HS-24, or close enough that it doesn't matter much.

 

Using the HS-24, the 18dB potential increase in headroom over a single driver/amp system means eight PowerSoft K-20 amplifiers, eight dedicated 220V-50A home run outlets and eight HS-24 drivers, each in a proper size enclosure and placed perfectly in the room.

 

If a single version of this system has a max top end of 126dB at 30 Hz, where room gain begins, and there are zero destructive reflections from eight of them in-room, you have headroom to 144dB from a system that only cost  $60,000, with no signal shaping or EQ hardware.

 

 Are you recommending that running a bridged K20 or A14K on a single HST-15 is required? That is certainly how it reads to me. Are you recommending a pair of your biggest amps to run a single DO HST-15 design? Before you respond that this is not a valid comparison to the original post, it most certainly is. The HS-24 has a larger cone and suspension bits, that is all. There is nothing in the coil / motor design that allows it to handle dramatically more power than the HST-15.

 

 

 

How much 10 Hz sine wave can the 2 x HST-15s take at 2M, GP in 5 cubes? I dunno, that's your milieu and for you to answer and ruminate over. How much power did it take to reproduce the Hulk punch effect in a room where the effect is transient in nature and full bandwidth? 9,000 watts. 8,915 watts to be exact. Using your metric, the amplifier would be rated at around 3,000 watts and thus there would be no way to even approach accurate reproduction of the effect without amplifier protection/distress stopping the experiment or a severely reduced playback level that would under-utilize the drivers capabilities. I think that's commonly referred to as an "amplifier-limited" system.

 

 

A well designed bass system IS amplifier limited in my opinion.

Especially with respect to the amplifier being able to easily bottom out the driver/s. I give a bit more leeway on the ability to burn the coils with sustained signals, but some thought should be given there as well. A driver limited system is a bad idea in my view.

 

If you want to suggest that it is proper, or required, to have enough amplifier on hand to make the driver smash into itself at half power, or burn the coil up in a few seconds, in order to properly reproduce the signal, or make full use of the particular drivers involved, that is your prerogative. Just don't expect me to agree with it. The last 1dB to 2dB from any system is the least clean and most stressful on it. By far the most difficult to squeeze out of a system as well, requiring loads more power and displacement for very minimal gains and with the offset cost of the system being increasingly unsafe in operation with certain potential signals. Allowing enough amplifier power on tap to bottom out the driver in band is not worth the tradeoff to me.

 

In an amplifier limited system the worst that happens is the signal gets squashed a bit and there's perhaps some amplifier clipping and some bad sounds. Nothing blows up. Turn down and enjoy another song. In a driver limited system the driver limits by the coil burning up or mechanically bottoming out. Both of which can require the purchase and install of another set of drivers. Money and time. I'll take amplifier limited myself.

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Hello All,   Sorry for the long radio silence.. work (as always) kept me from any progress on the cinema project. Last weekend however I finished all cabinets.. the 4 HS24 twins and the 4 LowMid

THE BASSFULL EIGHT...

Leons wasn't being unable to push to the system limits the point? That's what I always go for. I consider acceptable headroom achieved when I'm starting to get scared of breaking things in the structu

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Yes I am. I stand by the comment I made in the previous post. The content simply wasn't very demanding when the SP2-8K was used. The first night it was not Lone Survivor, it was some bass music that Brandon had that was being played back very loudly for an extended period. Some people push their systems hard and this type of content with extended synthetic bass tones is out there. To not plan for a difficult scenario for the system employed is foolish IMO. Call it childish or idiotic or whatever but people who buy bass systems usually like loud bass and will push their systems hard at some point. It should be planned for without resorting to having to keep an eye on everything that is played individually. In the case of burning a coil up you likely won't even notice until you start to smell burning adhesive at which point it may be too late already.

 

I've seen that Carver quote many times before and others from Tom Danley and Don Keele to the same effect. I agree with it completely. That does not mean that it is going to work out well when you have the 1500 watt rated amp on a driver rated at 150w program that bottoms out mechanically with 400w in the design being used. That is not the intention of the comments by these guys. It is implied that the other half of the equation is needed which is a speaker system that can safely make use of all that amplifier capability.

 

 

Yes I do and did. If I'm designing a system using a driver I've tested I will use the data I've pulled from it to make informed decisions on how much amplifier is a good match in the application and enclosure alignment it will be used in. The DIY tests are not about a finished system people should copy. They are about the driver performance and give information about the driver that can be used to develop a finished system for the app at hand using that driver. Personally I would not use any more amplifier than one that can indefinitely produce the amount of voltage applied during the loudest long term sine wave sweep in the sealed enclosure. This is very often close to a thermal limit for the coil. Peak voltage capability applied for the burst tests I'd also consider. If this is done the system should be reasonably safe from the coil burning up barring something with a truly strenuous duty cycle and the driver can use all or nearly all of its useful displacement but cannot be mechanically endangered. This type of system can be beat on quite severely and it will be safe no matter the signal applied to it in the majority of cases.

 

An entire host of unknown factors would need to be known to provide the "voltage required" for the Hulk scene at your place with your setup. It's off subject anyway.

 

Correct...Transient, dynamic, wide band content is not strenuous on drivers comparatively. I never made the comment that "no real power is required" for transients. What I said was that there is no real long term power applied to the drivers with this type of signal, a completely different comment which I stand by.

 

I would never design a bass system to use an amplifier which could produce maximum available cone excursion from the drivers using a wide bandwidth, complex signal. First off what wide bandwidth, complex signal? Secondly if a focused single frequency signal with the same voltage ever comes along, at a frequency that produces peak driver excursion, it is likely to bottom the driver out with bad result.

 

Your original comment that started this discussion, which is below, was about needing a K20 to power a single HS-24. Now granted I assume that you were trying to point out that to get the full 18dB on top of the data posted here you would need a full amp for each driver. That is true but only above 50Hz and only with very short duration burst signals. Below 30Hz a single K20 will happily drive 4 of the 24's to their limits quite comfortably. This was the whole start of the discussion which has now wandered off into the weeds a bit.

 

What does two HST-15's on half the power have to do with anything? Your original comment basically said that you will need a bridged A14K to run a SINGLE HST-15 or any other driver for that matter...The HST-15 has the same motor, same coil, same amount of excursion potential as the HS-24, or close enough that it doesn't matter much.

 

 

 Are you recommending that running a bridged K20 or A14K on a single HST-15 is required? That is certainly how it reads to me. Are you recommending a pair of your biggest amps to run a single DO HST-15 design? Before you respond that this is not a valid comparison to the original post, it most certainly is. The HS-24 has a larger cone and suspension bits, that is all. There is nothing in the coil / motor design that allows it to handle dramatically more power than the HST-15.

 

 

 

 

A well designed bass system IS amplifier limited in my opinion.

Especially with respect to the amplifier being able to easily bottom out the driver/s. I give a bit more leeway on the ability to burn the coils with sustained signals, but some thought should be given there as well. A driver limited system is a bad idea in my view.

 

If you want to suggest that it is proper, or required, to have enough amplifier on hand to make the driver smash into itself at half power, or burn the coil up in a few seconds, in order to properly reproduce the signal, or make full use of the particular drivers involved, that is your prerogative. Just don't expect me to agree with it. The last 1dB to 2dB from any system is the least clean and most stressful on it. By far the most difficult to squeeze out of a system as well, requiring loads more power and displacement for very minimal gains and with the offset cost of the system being increasingly unsafe in operation with certain potential signals. Allowing enough amplifier power on tap to bottom out the driver in band is not worth the tradeoff to me.

 

In an amplifier limited system the worst that happens is the signal gets squashed a bit and there's perhaps some amplifier clipping and some bad sounds. Nothing blows up. Turn down and enjoy another song. In a driver limited system the driver limits by the coil burning up or mechanically bottoming out. Both of which can require the purchase and install of another set of drivers. Money and time. I'll take amplifier limited myself.

 

Josh,

 

I really don't have the time to rehash a decade of posting on this subject, so I won't.

 

Your own tests suggest that what you say in the bolded paragraph is inaccurate. You are free to design any system as you see fit. Sorry, but I haven't seen any results from a system you've designed and built that agrees with what you've posted here.

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Josh,

 

I really don't have the time to rehash a decade of posting on this subject, so I won't.

 

Your own tests suggest that what you say in the bolded paragraph is inaccurate. You are free to design any system as you see fit. Sorry, but I haven't seen any results from a system you've designed and built that agrees with what you've posted here.

 

I'm not quite sure what you mean by this.  To my knowledge I'm fairly certain that Josh, other than in the testing he provides, doesn't run a bridged K10/20 on any single driver/enclosure in real world use.  He even discouraged me from using a bridged CC5500 on a single Ghorn, and that amp obviously has nothing on a K10/K20 in any area. 

 

Even with those crazy RF drivers he still runs 4 per K20. 

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And regarding the subs I've blown, I'm quite sure a clipped signal was a large contributing factor along with not having a limiter on the sub.  I will work on rectifying both situations to make sure a crazy 6/12/18Hz sine wave in a movie won't be a problem.  So let's not use my situation as any sort of data point for this discussion as it would be flawed.

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I'm not quite sure what you mean by this.  To my knowledge I'm fairly certain that Josh, other than in the testing he provides, doesn't run a bridged K10/20 on any single driver/enclosure in real world use.  He even discouraged me from using a bridged CC5500 on a single Ghorn, and that amp obviously has nothing on a K10/K20 in any area. 

 

Even with those crazy RF drivers he still runs 4 per K20. 

 

Josh says this in his testing blurb:

 

8. Maximum long term output is derived from the highest sweep level attained during the long term output compression testing. This is the highest long term sustained level attainable by the DUT within it's entire intended bandwidth, at which point some limiting condition whether amplifier, or excessive: excursion, noise, compression or distortion is in evidence in some part or all of the frequency range. (Note this does not mean that the subwoofer will handle a 100% duty cycle sine wave at this power level indefinitely! It will not!) The long term output compression test is meant to simulate the effects of high duty cycle use on the system but in a much more rapid manner. The long duration sine wave sweeps at the highest power levels are brutal on the systems and are meant to simulate many hours of playback of typical material with a MUCH lower duty cycle.Sine waves are 100% duty cycle so the voice coil gets heated relentlessly and in fact this test type kills more drivers than any other. Heavily compressed electronic music is only 25% duty cycle at most and typical music is far less than that so the average power is far less than that of the test signals used here.Therefore the voice coil and amplifier have some "downtime" to recharge and cool off a bit. Don't think of this measurement as output that can be sustained indefinitely...Think of it as a survival point...The sine wave test signals may generate and average power of 1500w from the amplifier into a system. Actual music or movie content that produces peak outputs of the same SPL levels might require the same amount of peak power but the average power seen over the same time period is more likely to be 200 watts than anywhere near the 1500 of the sine wave.

 

 

But in this thread he cites a 100% duty cycle combination of sines waves, run +15-20dB hot with triple digit harmonic distortion at the seats as the determinant of maximum amplifier power.

 

Please tell me you are not bringing up the now infamous SP2-8000 on a single HS-24 discussion as part of this? It is as simple as this...If the amp was clipping and the driver was not bottoming or burning up then the material was not that demanding or wasn't played very long. That is all that there is to it.

You were at Brandon's at this last GTG were you not? Some material played there WAS demanding.

 

 

And, he sticks by it.

 

Yes I am. I stand by the comment I made in the previous post. The content simply wasn't very demanding when the SP2-8K was used. The first night it was not Lone Survivor, it was some bass music that Brandon had that was being played back very loudly for an extended period. Some people push their systems hard and this type of content with extended synthetic bass tones is out there. To not plan for a difficult scenario for the system employed is foolish IMO. Call it childish or idiotic or whatever but people who buy bass systems usually like loud bass and will push their systems hard at some point. It should be planned for without resorting to having to keep an eye on everything that is played individually. In the case of burning a coil up you likely won't even notice until you start to smell burning adhesive at which point it may be too late already.

 

 

So, which is it? Is the top 2M GP sine sweep his metric or is a set of simultaneous 100% duty sines at whatever frequencies with a severely clipped signal his metric or is the fact that some people may regularly push any system beyond its capability his metric?

 

Also, I have 9 selectable system response curves available for just this scenario. There's a 15dB difference between them. This is not new information and the debates for and against limiters vs selectable curves were many and thorough:

 

ptVfmtO.png

 

There's a large disparity between the min/max bandwidth curves:

 

r8QKYez.png

 

Put another way for emphasis:

 

YMVhEN1.png

 

For those who are impressed more with maximum dBSPL and not accuracy.

 

Has Josh seen any of the data from the GTG he confidently cites as the reason Gage should use a 1000 watt amplifier, (or is it 2000 watts, but make sure you don't play Lone Survivor at +15dB hot) instead of the one that comes with the Mariana? Sorry, I'm gonna just piss on that thought a bit for how silly it is.

 

First off what wide bandwidth, complex signal?

 

 

Indeed. That's the million dollar question. One that carries the most weight, yet is NEVER addressed in these forums.

 

The Hulk punch scene is an excellent choice, as is the missile stike scene in Bourne legacy. Many others are also good possible candidates and could be chosen by popular vote in a poll thread. And, as Yates showed years ago, speclab comparisons from digits to reproduced versions are both extremely helpful and easily accomplished.

 

efsWATg.png

 

I guess it was the original statement that a K-20 is required for each driver to validate hundreds, if not thousands of comments that add +6dB for every doubling of drivers tested by Josh. Doesn't Dom's spreadsheet base sub performance on Josh's results of testing the SI HT-18? Of course, I'm correct and of course NO, I wasn't suggesting anyone do such an idiotic thing. Holy fuck, you guys, wake up... you really think that little of me?

 

And, the frequency band in those comments is... IRRELEVANT... doesn't matter what frequency, you need to double the amp with the driver to get the +6dB per doubling... period. As I said in the original comment... "Yes, very likely". Mike had trouble discerning whether or not that comment was sarcasm? Well then, yeah, there would be a problem if that's the case.

 

Are you recommending that running a bridged K20 or A14K on a single HST-15 is required? That is certainly how it reads to me. Are you recommending a pair of your biggest amps to run a single DO HST-15 design? Before you respond that this is not a valid comparison to the original post, it most certainly is. The HS-24 has a larger cone and suspension bits, that is all. There is nothing in the coil / motor design that allows it to handle dramatically more power than the HST-15.

 

 

Silly^^^ If that's how it reads to Josh, he needs remedial reading tutoring ASAP. We all know that's NOT how it reads to him, he's just yankin' my chain for some unknown reason.

 

But yes, I most certainly do recommend a 9K on a single DO HST-15 enclosure of the size used in the experiment. If I used Josh's metric, the amp would have been -6dB less power and would have severely clipped before seeing 45 mm one-way excursion during the HULK scene used as input. His suggesting that a 9K will fry the coils like the GTG incident caused roll eyes so severely that I still have a headache from it.

 

Adam has a single Blackbird DO enclosure driven by a 9K. The drivers are 2-1/2" VCs and probably rated at 500W each. Ask him if he ever burned the VCs so badly that his guests were exposed to extremely toxic fumes for hours using only 1/4 of the amplifier's potential. With great power come great responsibility. That should go without saying in a forum like this one.

 

Apologies for all of the confusion my simple statement of fact caused but it was to make a point that needs to be addressed here much more urgently than how to present the existing data in new ways, or whatever the latest fuss over fractions of decibel numbers is.

 

Josh uses a ridiculous monster of an amplifier on ridiculously absurd mains to test every DIY driver... and he recently upgraded the amplifier to +3dB more power. The same results are not to be expected at any frequency using a Behringer NU or similar amp. It's bullshit to suggest otherwise, yet you guys tenaciously cling to these silly arguments with me to the contrary.

 

The only case I'm aware of in which Josh used a shit amp vs his K-10 is the Chase vented sub:

 

Wa0Jz2O.png

 

The below tune number is irrelevant, as it would be with any vented sub. The only number that didn't increase was the max excursion frequency. Overall, the sub a completely different animal with a real amplifier vs the POS it came with and anyone who disagrees can get bent right now. I don't recall Josh melting anything and for those who read all sorts of dumb shit into everything I post, I'm not suggesting that the K-10 on 220V/50A mains wasn't capable of melting everything.

 

I wish it were a sealed sub because it would underscore my point. I wish real content had been used because it would underscore my point even more so.

 

As I said, if Josh chooses to design a sealed sub system that is amplifier limited, who cares? I certainly do not and I can't see how that has anything to do with the subject. He sure as hell doesn't choose to test single drivers with an amplifier limited rig.

 

The general rule in pro sound for centuries was "Always add +3dB of amplifier headroom". That's mostly because the systems are always pushed into compression and the headroom is used to compensate, but the rule also applies to HT subwoofer systems for transients. This practice requires thoughtful use and yields excellent results. Theory aside, I've posted those results for many, many years using accurate data from easily repeatable methodology.

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Josh says this in his testing blurb:

 

 

But in this thread he cites a 100% duty cycle combination of sines waves, run +15-20dB hot with triple digit harmonic distortion at the seats as the determinant of maximum amplifier power.

 

 

And, he sticks by it.

 

 

So, which is it? Is the top 2M GP sine sweep his metric or is a set of simultaneous 100% duty sines at whatever frequencies with a severely clipped signal his metric or is the fact that some people may regularly push any system beyond its capability his metric?

 

Also, I have 9 selectable system response curves available for just this scenario. There's a 15dB difference between them. This is not new information and the debates for and against limiters vs selectable curves were many and thorough:

 

ptVfmtO.png

 

There's a large disparity between the min/max bandwidth curves:

 

r8QKYez.png

 

Put another way for emphasis:

 

YMVhEN1.png

 

For those who are impressed more with maximum dBSPL and not accuracy.

 

Has Josh seen any of the data from the GTG he confidently cites as the reason Gage should use a 1000 watt amplifier, (or is it 2000 watts, but make sure you don't play Lone Survivor at +15dB hot) instead of the one that comes with the Mariana? Sorry, I'm gonna just piss on that thought a bit for how silly it is.

 

 

Indeed. That's the million dollar question. One that carries the most weight, yet is NEVER addressed in these forums.

 

The Hulk punch scene is an excellent choice, as is the missile stike scene in Bourne legacy. Many others are also good possible candidates and could be chosen by popular vote in a poll thread. And, as Yates showed years ago, speclab comparisons from digits to reproduced versions are both extremely helpful and easily accomplished.

 

efsWATg.png

 

I guess it was the original statement that a K-20 is required for each driver to validate hundreds, if not thousands of comments that add +6dB for every doubling of drivers tested by Josh. Doesn't Dom's spreadsheet base sub performance on Josh's results of testing the SI HT-18? Of course, I'm correct and of course NO, I wasn't suggesting anyone do such an idiotic thing. Holy fuck, you guys, wake up... you really think that little of me?

 

And, the frequency band in those comments is... IRRELEVANT... doesn't matter what frequency, you need to double the amp with the driver to get the +6dB per doubling... period. As I said in the original comment... "Yes, very likely". Mike had trouble discerning whether or not that comment was sarcasm? Well then, yeah, there would be a problem if that's the case.

 

 

Silly^^^ If that's how it reads to Josh, he needs remedial reading tutoring ASAP. We all know that's NOT how it reads to him, he's just yankin' my chain for some unknown reason.

 

But yes, I most certainly do recommend a 9K on a single DO HST-15 enclosure of the size used in the experiment. If I used Josh's metric, the amp would have been -6dB less power and would have severely clipped before seeing 45 mm one-way excursion during the HULK scene used as input. His suggesting that a 9K will fry the coils like the GTG incident caused roll eyes so severely that I still have a headache from it.

 

Adam has a single Blackbird DO enclosure driven by a 9K. The drivers are 2-1/2" VCs and probably rated at 500W each. Ask him if he ever burned the VCs so badly that his guests were exposed to extremely toxic fumes for hours using only 1/4 of the amplifier's potential. With great power come great responsibility. That should go without saying in a forum like this one.

 

Apologies for all of the confusion my simple statement of fact caused but it was to make a point that needs to be addressed here much more urgently than how to present the existing data in new ways, or whatever the latest fuss over fractions of decibel numbers is.

 

Josh uses a ridiculous monster of an amplifier on ridiculously absurd mains to test every DIY driver... and he recently upgraded the amplifier to +3dB more power. The same results are not to be expected at any frequency using a Behringer NU or similar amp. It's bullshit to suggest otherwise, yet you guys tenaciously cling to these silly arguments with me to the contrary.

 

The only case I'm aware of in which Josh used a shit amp vs his K-10 is the Chase vented sub:

 

Wa0Jz2O.png

 

The below tune number is irrelevant, as it would be with any vented sub. The only number that didn't increase was the max excursion frequency. Overall, the sub a completely different animal with a real amplifier vs the POS it came with and anyone who disagrees can get bent right now. I don't recall Josh melting anything and for those who read all sorts of dumb shit into everything I post, I'm not suggesting that the K-10 on 220V/50A mains wasn't capable of melting everything.

 

I wish it were a sealed sub because it would underscore my point. I wish real content had been used because it would underscore my point even more so.

 

As I said, if Josh chooses to design a sealed sub system that is amplifier limited, who cares? I certainly do not and I can't see how that has anything to do with the subject. He sure as hell doesn't choose to test single drivers with an amplifier limited rig.

 

The general rule in pro sound for centuries was "Always add +3dB of amplifier headroom". That's mostly because the systems are always pushed into compression and the headroom is used to compensate, but the rule also applies to HT subwoofer systems for transients. This practice requires thoughtful use and yields excellent results. Theory aside, I've posted those results for many, many years using accurate data from easily repeatable methodology.

 

I can see the logic with the +3db of headroom.  I agree that transients involving multiple frequencies are going to require more power from the amp than a single sine wave, however, no one has been able to answer just how much power that is yet.  However, 3db on top of what is able to bottom the driver will get you in trouble with some of todays content, so again I think we all agree that we have to use our brains when dealing with that kind of power.

 

However again, I think this has strayed a little bit from where it started. 

 

Here's what you said that started this whole thing:

 

"Using the HS-24, the 18dB potential increase in headroom over a single driver/amp system means eight PowerSoft K-20 amplifiers, eight dedicated 220V-50A home run outlets and eight HS-24 drivers, each in a proper size enclosure and placed perfectly in the room."

 

 

As Josh's measurements point out, the full power of the K10/K20 is only used at or over 50hz on pretty much every system.  That leaves wayyyyyyyyyyyyyy more than 3db, or 6db, or 9db (you can see where this is going) left in the tank for frequencies around 10hz. 

 

I completely agree with having a little amp headroom,  but your example with pairing a K20 with a single driver as the example has me scratching my head.  I personally wouldn't describe that as the proper amount of headroom.  :D

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Dave,

You have made a number of incorrect statements once again.

 

Lone Survivor may not even be 100% duty cycle I'm not sure TBH. That is NOT the only track that cooked a driver and I've seen most drivers smoke from content which was not HT stuff at all, it was music with nothing sub 30Hz in most cases.

 

I never said that I designed for 100% duty cycle. +15-20dB at the seats? What are you even talking about with that? Your first 3 comments don't even make sense to me. You are greatly simplifying by assuming the maximum long term sweep is all that there is to it and that's the amp you need. Often I'd de-rate that a bit for one. I don't know how many times I've tried to explain this. One more time here...

 

Sine wave sweep from 2-120Hz over a span of 23 seconds is BRUTAL on amp and driver.

 

While the sine wave sweeps the entire frequency range it will find the exact frequency range where the driver excursion is maximum.

 

Progressively increase signal until driver either taps out mechanically or obvious thermal issues rear their head.

 

Check the amount of voltage and power applied and the impedance. Figure a slight reduction in amplifier depending a bit on the exact specifics of the system, intended use, etc.

 

The amount of amplifier I try to design to is that which will not bottom the driver in the system used no matter the signal and will also be safe from overheating the coil with "most" content unless it has extremely demanding duty cycle for an extended period. Note that I didn't say 100% duty. Something like the Hulk is probably less than 10% when you get down to it save for very brief moments. Yeah you can still cook most anything with a sine wave at an impedance minimum with some duration. Most systems are not safe from this unless a limiter is employed to roll back the power over a specified time period. Which is not a bad idea if it is setup right. NEVER said Dave should downsize his amps. The scenario you mentioned would basically be like strapping 4 amps to one driver. I'll let those reading along make a judgment call on how that will go if they are not extremely careful. Clearly the current amp is up to the task of adequately powering the driver.

 

You seem to be advocating even MORE amplifier power than what I'm describing that I would use and that can easily mechanically break the driver with the wrong signal on top of being able to melt the coil. Double whammy. We are not going to see eye to eye on this. I've built enough systems and seen enough get pushed to their limits both thermally and mechanically that I prefer not to suggest "time bomb" systems to people. They have a few drinks one night they demo some new material to friends and they end up with dead woofers.

 

Chase vented sub illustrates this exactly. Notice there is NO extra output at a few bandwidths with the big amp. That is because any more and the driver probably gets damaged or dies in those bandwidths. Thermal issues aren't to be discounted either. How can the extra potential of the big amp be used without endangering the driver? It cannot without serious DSP power, creativity and some heavy duty limiters.  All of which you do not seem to be a fan of. The 500w amplifier supplied with the sub was the correct size to get everything out of it safely.

 

What really is crazy is we would probably spec about the same power plant for a sealed design using the same drivers. I might be a bit more conservative but not that much more conservative. I have never said that a K20 is needed to make use of any driver. I have always said that it is used with the passive systems so that the driver or cab that is being tested is the limiting factor as much as possible. Yes some people only look at the burst numbers and do a bunch of SPL bench racing based on it with little clue. There is enough data there to back out what a realistic amp/SPL/design would be. The amplifier is so big to be removed from the equation as much as possible. I can't help what other people do with snippets of data or arm chair engineering.

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As Josh's measurements point out, the full power of the K10/K20 is only used at or over 50hz on pretty much every system. 

So if you want to claim the output numbers over 50Hz, you will need that much amp.  Either way the point was that you get 3dB by doubling drivers unless you double the power with it.  I don't understand why there is so much confusion about this point. 

 

As far as the material at the 1st GTG not being demanding, I think it's pretty obvious at this point that demanding material is all we play at GTG's.  A couple examples from GTG1:

e489aa8aa105db09ec16f6039343d253.png

9f1b28bd6d327e3944588038f6955fa2.png

 

We shut down 2 amps.  I'd say that's pretty demanding.  No, we didn't take power measurements just like we didn't take measurements from the recent one where an amp from the same manufacturer rated for half of the power could easily have been pushed into outputting pure square waves and given too strong a signal from Beast's Marantz.  That would make analyzing the content's duty cycle useless and push the amp's RMS power value close to the DC rails.  Assuming the amp is appropriately sized here conflicts with the experience from GTG1. 

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I can see the logic with the +3db of headroom.  I agree that transients involving multiple frequencies are going to require more power from the amp than a single sine wave, however, no one has been able to answer just how much power that is yet.

 

It depends a lot on the transfer function of the signal chain as well as other more complicated factors.  The peak levels observed in digital content will not be the same as those seen by the amp unless there is no signal processing whatsoever. I imagine that a system with heavy low-end boost or Linkwitz Transform (12 dB?) will likely not benefit from much additional headroom because almost all the energy in the signal going to the amp will be low-end anyway.  However, this is a bit of a vague statement.  It'd be nice to have some hard numbers with pertinent examples.  Some day I'll maybe look into this.  The other thing is that while a math analysis can give a good idea of what the signal going to the amp looks like and therefore what kind of peak voltage demand is made, it's much harder to assess how the current demand of the content played into the particular driver (whose impedance profile may not even be stable) affects the amp and its performance.  However, yet again we can point out that current demands are often much greater at the lowest frequencies than at the higher frequencies.

 

I have to agree with what others are saying with respect to limiters.  Ideally, you design your system so you never hit the limiters, but the limiters are there just in case.  A development I think would be useful to see are smarter limiters that are frequency variable and designed with knowledge of the actual mechanical and thermal limits of the driver.  I've seen this sort of thing in fully-integrated / active speaker designs, but I don't know how well it works.  I imagine control based on a  model of power dissipation for a particular speaker and its impedance profile could be very effective to protect voice coils from burning, but for excursion the problem may be a lot harder.  I'm not sure if excursion is as easy to predict.

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So if you want to claim the output numbers over 50Hz, you will need that much amp.  Either way the point was that you get 3dB by doubling drivers unless you double the power with it.  I don't understand why there is so much confusion about this point. 

 

Everyone understands the doubling of both drivers and power gains 6db, so there's no confusion there from anyone.
 
There's confusion because it's a blanket statement that not specific enough to be accurate, and even if you add the specifics it doesn't apply to any system in existence.
 
I'll elaborate. 
 
Here's the original quote:
 
"Using the HS-24, the 18dB potential increase in headroom over a single driver/amp system means eight PowerSoft K-20 amplifiers, eight dedicated 220V-50A home run outlets and eight HS-24 drivers, each in a proper size enclosure and placed perfectly in the room."
 
 
Let's add the specifics:
 
"Using the HS-24, the 18dB potential increase in headroom over a single driver/amp system, only at 50hz and up AND while using strictly CEA bursts, means eight PowerSoft K-20 amplifiers, eight dedicated 220V-50A home run outlets and eight HS-24 drivers, each in a proper size enclosure and placed perfectly in the room."
 
Who/what system does this statement apply to?  None.
 
Additionally, wouldn't you agree that bringing a bridged K20 to full power at 50hz and up on ANY single driver driver with real movie/music content (meaning it's not a single CEA burst that lasts a fraction of a second) would be detrimental to said driver?  Yes, the RF T3, IPAL, or BHS-24 may last in the realm of seconds, but no one would say even those are a safe bet, and there's certainly no practical real world application for this scenario which is my point in this.
 
Again, that's why there's confusion.  It's a blanket statement, that I would describe as inaccurate since it leaves out the key specifics, that doesn't apply to anyone.  
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The only case I'm aware of in which Josh used a shit amp vs his K-10 is the Chase vented sub:

 

FWIW, Josh did also do passive tests on the Funk 18.0 and 18.0C, along with tests using their standard 2.4kW and 0.8kW amps. Not quite the same gap as with the Chase unit, but an interesting comparison nonetheless.

 

18.0

post-3442-0-24380500-1452614233_thumb.jpg

 

18.0c

post-3442-0-78061300-1452614233_thumb.jpg

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So if you want to claim the output numbers over 50Hz, you will need that much amp.  Either way the point was that you get 3dB by doubling drivers unless you double the power with it.  I don't understand why there is so much confusion about this point. 

 

I don't understand the confusion either but I think we are starting to get on the same page. I hope. Everyone gets that it takes double the power and double the drivers to get the full 6dB or at least I would hope so. Most of the confusion appears to stem from the bolded part. No one here was claiming anything related to burst data or even output numbers at all?

 

I'd like to believe that most of us reading along or posting here also understand what I've tried to explain about why the big amp is used for the measurements and why ALL of the measurements need to be looked at in depth for the passive systems in order to back out what a realistic system design with "proper" power would be. I also believe that everyone is on the same page that big bass requires a lot of amplifier reserve and displacement. No argument there from me. No one was saying to run 8 24's with a 1000w BASH plate amp. That's silly. However running a 8kw amp on each 24 is also just as silly. The sensible solution is something in between that fits the system design and allows it to utilize maximum potential but doesn't unnecessarily endanger its long term operation.

 

Correct Steve.

 There have been a few others I cannot post the data for. Much the same story. Note that there isn't much or any more useful output from the big amp in the deep bass. The factory amps are well matched to the requirements.

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Leons how is the build going? What did you decide on for power etc...Hope we didn't run you off with our argumentative techno-babble. Some of us get like that sometimes and you never can tell what thread it's going to occur.

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So I will be moving soon, and will be system-less for quite a bit.  I was thinking of filling the temporary void with this:

 

WStudio_6-13-2014_137.jpg

 

But I will obviously need more power for those full-range transients beyond what the built-in amp will simply not deliver.  

 

Should I buy a PowerSoft K8, K10 or K20, or just go-for-broke with multiple Lab Gruppens?

 

I mean, this thing is supposed to be BAD ASS.....I need enough power so that Scissor/Shear recordings, Fireworks, BEQ stuff, TIH, EoT, Lone Survivor, Pixels, Frankenstein's Army and all that trash had better be ready to be played back properly...driver limits be damned.  I don't care that the drivers will explode in a blaze of glory for any multi-kilowatt signal that lasts for more than one ten-thousandth of a second.....just think of how awesome that one ten-thousandth of a second will be.....before I have to call the fire department....but calling the fire department isn't exactly bad ass, and it is cold outside....bonfire for the neighborhood it is.....Beer is in the shop fridge anyway.....

 

093207098512.jpg

 

JSS 

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Additionally, wouldn't you agree that bringing a bridged K20 to full power at 50hz and up on ANY single driver driver with real movie/music content (meaning it's not a single CEA burst that lasts a fraction of a second) would be detrimental to said driver?  Yes, the RF T3, IPAL, or BHS-24 may last in the realm of seconds, but no one would say even those are a safe bet, and there's certainly no practical real world application for this scenario which is my point in this.

 

As Bosso has pointed out a few times now, that metric is not useful for anything in real world content.  You seem to be dwelling on his 1st sarcastic post and not reading any of the following explanation.  You really think his point is to power a 24 with 20kW?  It's not.  Powering a sealed 24 with <4kW seems to be what you guys think is the answer because of an incident with one model of amp vs. a 24 and no clue as to what signal the amp was fed or outputting.  I couldn't disagree more.  I feel confident based on my amp measurement experience that I would in no way harm a 24 with peaks in excess of 4kW on tap.  An inexperienced user however could no doubt do damage with less than 4kW at their disposal.  I prefer a system where the only limiter is my discretion.  So far I've damaged zero amps and drivers so evidently it works well enough. 

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As Bosso has pointed out a few times now, that metric is not useful for anything in real world content.  You seem to be dwelling on his 1st sarcastic post and not reading any of the following explanation.  You really think his point is to power a 24 with 20kW?  It's not.  Powering a sealed 24 with <4kW seems to be what you guys think is the answer because of an incident with one model of amp vs. a 24 and no clue as to what signal the amp was fed or outputting.  I couldn't disagree more.  I feel confident based on my amp measurement experience that I would in no way harm a 24 with peaks in excess of 4kW on tap.  An inexperienced user however could no doubt do damage with less than 4kW at their disposal.  I prefer a system where the only limiter is my discretion.  So far I've damaged zero amps and drivers so evidently it works well enough. 

 

"As Bosso has pointed out a few times now, that metric is not useful for anything in real world content."

 

I assume Josh performs that test for a reason, so I wouldn't be so quick to say there isn't any point to it. 

 

 

"You seem to be dwelling on his 1st sarcastic post and not reading any of the following explanation."

 

Was his next statement in the same post sarcastic as well about the K10/K20 having no signal shaping/EQ abilities?

 

"If a single version of this system has a max top end of 126dB at 30 Hz, where room gain begins, and there are zero destructive reflections from eight of them in-room, you have headroom to 144dB from a system that only cost  $60,000, with no signal shaping or EQ hardware."

 

 

 

"Powering a sealed 24 with <4kW seems to be what you guys think is the answer because of an incident with one model of amp vs. a 24 and no clue as to what signal the amp was fed or outputting.  I couldn't disagree more."

 

This must be in response to someone else, because I agree that we don't know what was fed to that amp or what it was outputting.  I certainly don't recall saying anything negative about the HS-24s abilities based on this incident. 

 

 

"I feel confident based on my amp measurement experience that I would in no way harm a 24 with peaks in excess of 4kW on tap.  An inexperienced user however could no doubt do damage with less than 4kW at their disposal.  I prefer a system where the only limiter is my discretion.  So far I've damaged zero amps and drivers so evidently it works well enough. "

 

With proper limiters in place I agree that the HS-24 could be paired quite nicely with a ~4kw amp.  No argument from me on this. 

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Everyone understands the doubling of both drivers and power gains 6db, so there's no confusion there from anyone.
 
There's confusion because it's a blanket statement that not specific enough to be accurate, and even if you add the specifics it doesn't apply to any system in existence.
 
I'll elaborate. 
 
Here's the original quote:
 
"Using the HS-24, the 18dB potential increase in headroom over a single driver/amp system means eight PowerSoft K-20 amplifiers, eight dedicated 220V-50A home run outlets and eight HS-24 drivers, each in a proper size enclosure and placed perfectly in the room."
 
 
Let's add the specifics:
 
"Using the HS-24, the 18dB potential increase in headroom over a single driver/amp system, only at 50hz and up AND while using strictly CEA bursts, means eight PowerSoft K-20 amplifiers, eight dedicated 220V-50A home run outlets and eight HS-24 drivers, each in a proper size enclosure and placed perfectly in the room."
 
Who/what system does this statement apply to?  None.
 
Additionally, wouldn't you agree that bringing a bridged K20 to full power at 50hz and up on ANY single driver driver with real movie/music content (meaning it's not a single CEA burst that lasts a fraction of a second) would be detrimental to said driver?  Yes, the RF T3, IPAL, or BHS-24 may last in the realm of seconds, but no one would say even those are a safe bet, and there's certainly no practical real world application for this scenario which is my point in this.
 
Again, that's why there's confusion.  It's a blanket statement, that I would describe as inaccurate since it leaves out the key specifics, that doesn't apply to anyone.  

 

 

I seem to live in a parallel dimension. Please explain how one would use amplifier 'X' for only 50 Hz and up only? Not possible. The amp used is the amp used. According to conventional wisdom of this forum, all of Josh's DIY numbers are pretty useless because they are impossible to repeat in the real world.

 

If you limit to sine wave sweep excursion at 10 Hz, you get power requirement 'A'.

 

If you limit to sine waves-turned-square waves from a severely clipped signal to the driver while playing a scene from Lone Survivor (otherwise known here as "demanding material") you get power requirement 'B'.

 

If you employ aggressive progressive limiters and high pass filtering, you get power requirement 'C' (the choice of 100% of commercial subwoofer designers).

 

If you employ conservative hard limiter and no HPF, you get power requirement 'D' accompanied by a disclaimer for idiots.

 

If you want to match Josh Ricci's Data_Bass THD-limited long term/short term 1/3 octave frequencies and 10-80 Hz averages and maximum sine sweep numbers, you need a K-10 on a dedicated 220V-50A line. Add additional amplifier as you double drivers if you want to add +6dB to those numbers each doubling... blanket... period. (There is no frequency band discrimination possible. Please explain what is the brain disorder that clouds this fact?)

 

As for the GTG segment that Josh refers to as being "infamous" and is concluding involved material that was not demanding... If the HS-24 is being driven to within a hair breadth of X-mech when the 8000 watt amplifier on a dedicated 120V-30A line shuts down, exactly what should that scenario be referred to as if not demanding? That BS gets a complete pass while youse guys are still gnawing on the K-20/driver sentence?

 

As for the scene in Lone Survivor, we can safely eliminate the 6.5 Hz portion of the source as the sub under test is down -18dB at 6 Hz. Paul and I are running a thorough examination of the data gathered and digits involved in the latest GTG incident that Josh has decreed was the result of demanding material in contrast to the infamous GTG incident. Adam, Paul & I had decided not to mention that incident at all but since Josh has let that cat out of the bag by referencing it here, after we run the conclusions past Dave, we may or may not discuss those conclusions.

 

I'll just say again, citing any results from the antics involved at a typical GTG, good or bad, is no way for anyone to design a sub.

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Hello all.

Regarding build progres:

I have been out of the country for the last two weeks so I could not check regarding build progress on the cabinets.
I will be back next monday. I hope they.... If not I....

Regarding amp power:
I have 4 ohm HS24s
my gut feeling tels me that one channel of a QSCPL380 per HS24 (2500W / 4ohm) is not a bad match but on the lower/minimum side needed...
my gut feeling also tels me that a bridged K20 per HS24 (18000W 4 ohm)  is on the high side of the scale... probably off the scale...
I now tend towards fp14000 clones.. one channel per HS24 (4600W) per driver... if driven with care its seems like a "solid headroom option"
the only issue is the reliability of the chinese clones.. I ordered 4 Sanway fp10000 clones a year ago .. 3 work perfect so far.. the 4th did nothing...  
I will compare the PL380 and FP14000 before I make a decision.. I will post my findings...

 

Regarding filters:
I have a Marantz AV8801 processor (it has 2 subwoofer outputs)

What would you consider a good cross-over unit to filter these sub outputs once they come out of the Marantz..

I'm planning to use the sub outs as follows:
sub-out 1 will drive the 8 HS24's (crossed zero to 35Hz maby 40Hz) so they will do only what they're good at... move air..
sub out 2 will drive the 4 LAB subwoofers (crossed 35 to 80Hz) that's what these are good at.

 

I know mini dsp is an option, do you guy's know any other/better options.?

and one more thing... how the heXX can I get an icon... whatever I try It won't work...

 

thank's

best regards,
Leon

 

 

 

 

 

 

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"As Bosso has pointed out a few times now, that metric is not useful for anything in real world content."

 

I assume Josh performs that test for a reason, so I wouldn't be so quick to say there isn't any point to it. 

 

 

"You seem to be dwelling on his 1st sarcastic post and not reading any of the following explanation."

 

Was his next statement in the same post sarcastic as well about the K10/K20 having no signal shaping/EQ abilities?

 

"If a single version of this system has a max top end of 126dB at 30 Hz, where room gain begins, and there are zero destructive reflections from eight of them in-room, you have headroom to 144dB from a system that only cost  $60,000, with no signal shaping or EQ hardware."

Let me get this straight... you assume that Josh performs the test for a reason so even though you can't point to it, he gets a pass.  Then you go into Dave's post with a magnifying glass to grasp at straws to find the bold print above which has very little to do with his point?  Funny how you didn't act like this when we were face to face.  I'll leave you to your online Bosso crusade. 

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Let me get this straight... you assume that Josh performs the test for a reason so even though you can't point to it, he gets a pass.  Then you go into Dave's post with a magnifying glass to grasp at straws to find the bold print above which has very little to do with his point?  Funny how you didn't act like this when we were face to face.  I'll leave you to your online Bosso crusade. 

 

Well, maybe using the word "assume" was being a little too presumptuous on my part.  I'll re-phrase:  Josh doesn't run a battery of different tests without reason. 

 

Dave's whole post was bizarre, and that's what started this whole thing.  It doesn't take a magnifying glass to see that.

 

When we were face to face, I told you and Dave the exact same thing about my experiences with a sealed system in my old room that I've posted online.  There was no deviation.  However, Dave's responses to the exact same information in person vs. online was a 180 degree turn.  He wasn't the same sarcastic and passive aggressive person that he is online.

 

EDIT:  I've already covered all of this in the GTG thread, so you have anything else to say about it, you have my cell or you can send me a PM. 

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