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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => LAB Lounge => Topic started by: Jeff Schoonover1 on September 26, 2017, 09:24:39 PM
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It used to be that Crown set the gold standard across the board. One of their big selling points was that they guaranteed that an amp would put out a minimum of X watts, from 20-20KHz continuously.
Fast forward to now, their top-end stuff is competitive, but others have bested even that. In the DJ and small PA market, we have the XTi series. I have an XTi 4000 for mids, and am pretty happy with it. About 3KW, and DSP for a good price. But - the specs aren't measured as they once were.
Anyhow, I'm thinking of an XTi 6002 for a dual 18" sub I just built. The XTi specifies 6,000 watts - BUT ONLY AT 1 kHz! What does this mean? Is my amp only going to do 3,000 watts at 40 Hz where I need it? Am I getting gypped and ought to shop for something else?
Has anyone measured or know the math on what these amps will 'really' do in a musical spectrum range? What will an XTi 6002 put out continuously from 30 Hz to 100 Hz?
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It used to be that Crown set the gold standard
Please go to your profile and change the "Name" field to your real first and last name as required by the posting rules displayed in the header at the top of the section, and in the Site Rules and Suggestions (http://forums.prosoundweb.com/index.php/board,36.0.html) in the Forum Announcements section, and on the registration page when you registered.
Mac
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Done.
Please go to your profile and change the "Name" field to your real first and last name as required by the posting rules displayed in the header at the top of the section, and in the Site Rules and Suggestions (http://forums.prosoundweb.com/index.php/board,36.0.html) in the Forum Announcements section, and on the registration page when you registered.
Mac
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Not only do you need a test to see what wattage it will put out at your desired frequency, you also need to know how long it will hold it before the inevitable current sag. For some styles of music like EDM with sustained bass notes. this is more important than other genres. I will tell you that when I swapped my xti6000 for an ITech 6000, the difference was not subtle, and it seemed to have plenty reserve current where the xti seemed to be limited by whatever instantaneous current it could draw from the wall and not much more.
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Not only do you need a test to see what wattage it will put out at your desired frequency, you also need to know how long it will hold it before the inevitable current sag. For some styles of music like EDM with sustained bass notes. this is more important than other genres. I will tell you that when I swapped my xti6000 for an ITech 6000, the difference was not subtle, and it seemed to have plenty reserve current where the xti seemed to be limited by whatever instantaneous current it could draw from the wall and not much more.
I was afraid of this. So basically, if you have a very stable 15-20-amp AC source, you might get bursts of 6,000 watts at 1K... Swell.
I have been looking at used I-Tech 8K's, but they're discontinued by Crown, and I've read plenty of horror stories - plus apparently, they're incredibly difficult/expensive to fix. I'm just a po' musician, not a corporate sound company. I need something for about $1,500 max, not $3K.
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I was afraid of this. So basically, if you have a very stable 15-20-amp AC source, you might get bursts of 6,000 watts at 1K... Swell.
I have been looking at used I-Tech 8K's, but they're discontinued by Crown, and I've read plenty of horror stories - plus apparently, they're incredibly difficult/expensive to fix. I'm just a po' musician, not a corporate sound company. I need something for about $1,500 max, not $3K.
Are you doing EDM with *sustained* full power output requirements? I ask because LIVE music, with humans playing instruments and singing, has a peak-to-average ratio of >20dB, and those peaks are typically of relatively short duration, on the order of 20ms or so.
Building amplifiers that can deliver full rated power indefinitely is tremendously expensive these days when the market for power amps in general does not require such performance. The amp manufacturers have responded by building to a lower duty cycle standard and lowering their prices (remember when $1/watt was cheap?) accordingly.
As for the power output spec at 1kHz, that's because it's an easy mark to hit. In general terms the power supply can only recharge at a rate equal to or lower than the AC line frequency, so the lower the reproduced frequency at greater magnitude, the lower the output will be. This is not limited ot the XTi, either, it's one of the those laws of physics things that eventually customers decided they would not pay higher equipment prices to compensate for.
That all said, find an amp that puts out even 2000w/ch and power up your subs... and let it run for a couple of minutes or until the speakers catch fire.
The fact is that your subs will NOT dissipate 3000 Watts of heat, nor will they mechanically survive that power at subwoofer frequencies for very long.
While I understand the confusion these market-based power specifications have created (you're neither first nor will be last), you are tilting at windmills, Mr. Quixote.
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I was afraid of this. So basically, if you have a very stable 15-20-amp AC source, you might get bursts of 6,000 watts at 1K... Swell.
I have been looking at used I-Tech 8K's, but they're discontinued by Crown, and I've read plenty of horror stories - plus apparently, they're incredibly difficult/expensive to fix. I'm just a po' musician, not a corporate sound company. I need something for about $1,500 max, not $3K.
Keep in mind the 6000watts at 1K Crown claims is in 4ohm bridged mode
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Keep in mind the 6000watts at 1K Crown claims is in 4ohm bridged mode
For about 50ms or less...
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For about 50ms or less...
Yep...20ms
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I have a pair of xti6002 amps. For a while one ran a pair of Srx725 tops, and I had a pair of itech amps running subs. A few weeks ago I reconfigured the amp rack and since the. It's been an itech on tops, and each xti6002 bridges into a SRX728 sub.
Screw the numbers you're reading. The subs go loud with a 6002 bridged into each!
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Are you doing EDM with *sustained* full power output requirements?
I am a bass player, the rig will be used onstage for large shows where I'm often competing with hard-hitting drummers and two marshall stacks from guys who haven't figured out that loud stage volume = bad sound, and sound men who take all bass out of the mix, except hugely overbearing and non-linear kick-drum boom.As for the power output spec at 1kHz, that's because it's an easy mark to hit. In general terms the power supply can only recharge at a rate equal to or lower than the AC line frequency, so the lower the reproduced frequency at greater magnitude, the lower the output will be.
This is the most excellent and concise definition of how these new PWM amps are different than old-school transformer based amps. I kinda knew this, but couldn't have defined it so precisely.That all said, find an amp that puts out even 2000w/ch and power up your subs... and let it run for a couple of minutes or until the speakers catch fire.
This was my summation at first as well. I was going to put it on my XTi 4000 at their advertised 3,200W and see how it sounds, and go from there. But, having spoken with a couple of my bosses who own Clair Bros. rigs, they're pretty sold on the idea of having at least 2-3 times the continuous power rating. Based on the clarity depth and volume of the low end produced, I know they're on to something.The fact is that your subs will NOT dissipate 3000 Watts of heat, nor will they mechanically survive that power at subwoofer frequencies for very long.
I might be inclined to agree, but I have the box loaded with twin Eighteen Sound TLW3000. AES power is 1,800W, and Program Power is 3,600 with peak bursts to 10KW....you are tilting at windmills, Mr. Quixote.
NiceKeep in mind the 6000watts at 1K Crown claims is in 4ohm bridged mode
This box will be wired for 4 Ohms.
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Screw the numbers you're reading. The subs go loud with a 6002 bridged into each!
LOUD is do-able now with my XTi 400 and a couple of 15" Eminence-loaded boxes. What I'm after is loud, but only while maintaining linearity - I.E. low distortion and clean, detailed, accurate reproduction. I want to hear the notes. I don't just want loud, but with overhang and boominess, like I have now.
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I am a bass player, the rig will be used onstage for large shows
There is a wide chasm between bass player on a loud stage and festival level EDM playback. I've played in loud death metal and hardcore bands next to Mesa half stacks and my little 200 watt Peavey tube amp feeding a Mesa 4x10 never ran out of gas.
What are you guys gonna do when you walk into a venue and backline power is limited to a single 15A circuit?
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I have a pair of xti6002 amps. For a while one ran a pair of Srx725 tops, and I had a pair of itech amps running subs. A few weeks ago I reconfigured the amp rack and since the. It's been an itech on tops, and each xti6002 bridges into a SRX728 sub.
Do you hear a difference? I'm thinking if the 6002 can power one of those adequately, I may be able to do fine with a 6002. Where are you drawing power? The wall, or do you have distro power?
Would you by chance have compared the 6002 with the 4002? Is it really twice the amp?
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There is a wide chasm between bass player on a loud stage and festival level EDM playback.
Agreed, but there are plenty of low, sustained notes produced by bass guitar at times. While they aren't a perfect sine, like EDM, they're still pretty heavy with the fundamental frequencies.
I've played in loud death metal and hardcore bands next to Mesa half stacks and my little 200 watt Peavey tube amp feeding a Mesa 4x10 never ran out of gas.
I said it before, but I have a 2x15" + 2x10/horn rig powered by an XTi4000. Loud is not the problem. Fidelity and linear response - while being loud - is the goal.
What are you guys gonna do when you walk into a venue and backline power is limited to a single 15A circuit?
I don't play in rooms like that, but if I did, I'm certain my greatly lowered volume would only require a small fraction of that.
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It used to be that Crown set the gold standard across the board. One of their big selling points was that they guaranteed that an amp would put out a minimum of X watts, from 20-20KHz continuously.
Fast forward to now, their top-end stuff is competitive, but others have bested even that. In the DJ and small PA market, we have the XTi series. I have an XTi 4000 for mids, and am pretty happy with it. About 3KW, and DSP for a good price. But - the specs aren't measured as they once were.
Anyhow, I'm thinking of an XTi 6002 for a dual 18" sub I just built. The XTi specifies 6,000 watts - BUT ONLY AT 1 kHz! What does this mean? Is my amp only going to do 3,000 watts at 40 Hz where I need it? Am I getting gypped and ought to shop for something else?
Has anyone measured or know the math on what these amps will 'really' do in a musical spectrum range? What will an XTi 6002 put out continuously from 30 Hz to 100 Hz?
Nobody makes amps for continuous power, and they haven't for several decades because music is not continuous.
The specific question about why spec power at 1kHz is because you can print a slightly larger power number at frequencies well above reservoir cap ripple. In real terms (like dBW) the power difference is insignificant, but consumers making purchase decisions think 10 or 20 more watts is important.
JR
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10% (typical difference between 1K vs 20-20K measurements) more or fewer watts is pretty insignificant in volume difference.
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Ok, so it seems that my fears were unfounded. A promised 6KW @ 1KHz from an XTi will be just about the same as from any other amp delivering 6KW with 20-20K measurement - Cool!
Another observation and question :
I am of the opinion that watts are watts. Specifically, if an XTi is giving 6KW cleanly, within all of its normal operating parameters (no clipping, no thermal limiting, and (ideally) adequate power supply -no voltage sag) There will be no difference, audible or otherwise, between that and an i-Tech HD, or any other high dollar amp with the same output capability. The difference in price comes from robust-ness, protection, heat dissipation, features like better DSP, etc.
Yay/Nay?
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within all of its normal operating parameters (no clipping, no thermal limiting, and (ideally) adequate power supply -no voltage sag) There will be no difference,
With this caveat, yay.
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Ok, so it seems that my fears were unfounded. A promised 6KW @ 1KHz from an XTi will be just about the same as from any other amp delivering 6KW with 20-20K measurement - Cool!
Another observation and question :
I am of the opinion that watts are watts. Specifically, if an XTi is giving 6KW cleanly, within all of its normal operating parameters (no clipping, no thermal limiting, and (ideally) adequate power supply -no voltage sag) There will be no difference, audible or otherwise, between that and an i-Tech HD, or any other high dollar amp with the same output capability. The difference in price comes from robust-ness, protection, heat dissipation, features like better DSP, etc.
Yay/Nay?
Keep in mind though that most steady output for that sized amp will be in the hundreds of watts, not thousands. For this amp to generate 6000 watts I'm going to guess it would be pulling around 50 amps from the wall (@110v) to be able to do it:
1/3 Power Pink Noise Typical of program material at extreme clip @ 2ohms 35.2 amps 989 watts (110v)
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I seriously doubt adding more power will cure what you are unhappy about. I would point to your speakers as a more likely culprit.
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Keep in mind though that most steady output for that sized amp will be in the hundreds of watts, not thousands. For this amp to generate 6000 watts I'm going to guess it would be pulling around 50 amps from the wall (@110v) to be able to do it:
1/3 Power Pink Noise Typical of program material at extreme clip @ 2ohms 35.2 amps 989 watts (110v)
I don't think so. I'm not an electrical engineer but have a basic understanding of electronics. AC volts from the wall don't convert to the DC voltage applied by the amp to the speaker by simply using Ohms Law. There's the conversion of AC wall power to the DC power used by speakers, the ability of the amp to store voltage, varying duty cycle (Even at full power, there are times during the signal no current is being given.) Varying resistance of the load (Speakers vary resistance by frequency) Amplifier efficiency/power lost, etc.
In short, my understanding is that consumer level amps like this can, in fact, deliver what they say they deliver from AC 12V 20A circuits. There are of course amps (Powersoft K20) which can only deliver their maximum with greater AC supply Voltage/Current, and plainly say so in their literature, but they will do far more than 6KW.
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I seriously doubt adding more power will cure what you are unhappy about. I would point to your speakers as a more likely culprit.
Hard to guess whether you mean. If you're talking about what I have now (two 15" speakers in two 4.5Cu.Ft. boxes. Each speaker has a program power rating of 700W, and powered by an XTi 400 pushing 3,200 W into both), then yes, my limitations exist chiefly in the speakers. My new box, has two 18" TLW3000's, each rated at 3,200W program power. They're in a 16 Cu.Ft. box. The ability of this box vs. what I have now is vastly superior to my 2x15" setup - assuming I can power it correctly, which is why I started this thread.
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I don't think so. I'm not an electrical engineer but have a basic understanding of electronics. AC volts from the wall don't convert to the DC voltage applied by the amp to the speaker by simply using Ohms Law. There's the conversion of AC wall power to the DC power used by speakers, the ability of the amp to store voltage, varying duty cycle (Even at full power, there are times during the signal no current is being given.) Varying resistance of the load (Speakers vary resistance by frequency) Amplifier efficiency/power lost, etc.
In short, my understanding is that consumer level amps like this can, in fact, deliver what they say they deliver from AC 12V 20A circuits. There are of course amps (Powersoft K20) which can only deliver their maximum with greater AC supply Voltage/Current, and plainly say so in their literature, but they will do far more than 6KW.
You're right, you are not an electrical engineer. The voltage applied to a speaker by an amplifier is AC, not DC. Hook a battery up to your speaker and let me know what you hear.
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I am a bass player, the rig will be used onstage for large shows where I'm often competing with hard-hitting drummers and two marshall stacks from guys who haven't figured out that loud stage volume = bad sound, and sound men who take all bass out of the mix, except hugely overbearing and non-linear kick-drum boom.
I am surprised nobody has pointed out the absurdity of placing a double 18" on stage for your bass rig. First it's going to destroy the stage, get into all the microphones and most important not cover the room well.
It may bathe you in the visceral feedback that you like but ultimately it is not going to achieve your goal and is very disruptive. I don't know any engineer worth his salt that would allow you to run that on their stage, certainly lot at anywhere near it's potential.
If you need the tactile feel Mike Sokol has an article on a transducer platform that will is a great idea. The trend is to lower stage volume, not raise it.
http://www.prosoundweb.com/channels/live-sound/now-hear-this-monitoring-approaches-in-the-quest-for-a-semi-silent-stage/
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You're right, you are not an electrical engineer. The voltage applied to a speaker by an amplifier is AC, not DC. Hook a battery up to your speaker and let me know what you hear.
Just the term "frequency" should be enough to tell it is an AC signal, not DC.
DC has no "frequency".
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You're right, you are not an electrical engineer. The voltage applied to a speaker by an amplifier is AC, not DC. Hook a battery up to your speaker and let me know what you hear.
So you're certain that amplifiers (any electronic item, really) don't convert AC from the wall, into DC for use by its various components?
Plug a speaker into a wall outlet and let me know what you hear. :)
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So you're certain that amplifiers (any electronic item, really) don't convert AC from the wall, into DC for use by its various components?
Plug a speaker into a wall outlet and let me know what you hear. :)
If the speaker is rated at about 2000 watts you would get a 60hz tone.
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I am surprised nobody has pointed out the absurdity of placing a double 18" on stage for your bass rig. First it's going to destroy the stage, get into all the microphones and most important not cover the room well.
It may bathe you in the visceral feedback that you like but ultimately it is not going to achieve your goal and is very disruptive. I don't know any engineer worth his salt that would allow you to run that on their stage, certainly lot at anywhere near it's potential.
If you need the tactile feel Mike Sokol has an article on a transducer platform that will is a great idea. The trend is to lower stage volume, not raise it.
http://www.prosoundweb.com/channels/live-sound/now-hear-this-monitoring-approaches-in-the-quest-for-a-semi-silent-stage/
I have been using IEMS for a couple years now. I even own my own mixer and splitter snake for a while band to do so if they desire. You're preaching to the choir. I prefer no noisemakers onstage at all. But, many of the acts I work with still think they need to "feel it" onstage. These guys bring dual Marshall stacks to club gigs, seriously. Coupled with the fact that most of the sound guys at this level put zero bass in the mix. It's all about kick drum, and vocals for them. Thirdly, it's not even about loud so much, as to be able to go low, cleanly at moderate volumes. 30-40 Hz at 110-120 is easy. Hut to do it with low distortion and linearity is difficult. Impossible with bass rigs available at guitar center.
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If the speaker is rated at about 2000 watts you would get a 60hz tone.
Yep. Hence the need for an amplifier, as I'd like to make some other sounds as well.
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So you're certain that amplifiers (any electronic item, really) don't convert AC from the wall, into DC for use by its various components?
Plug a speaker into a wall outlet and let me know what you hear. :)
Of course the "internals" use DC, but the output stage generates AC to drive the speaker.
Oh, I HAVE plugged a driver right into a wall outlet. Worked quite nicely. (It was no "normal" driver)
Others here have seen this demo as well. Just sayin....
Chris.
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If the speaker is rated at about 2000 watts you would get a 60hz tone.
Depending on the impedance at 60Hz.
There are some speakers rated at a couple of hundred watts that you can plug directly into the wall-because at 60Hz the impedance is pretty high, so the actual power dissipated by the loudspeaker in under its rating.
But in Europe, that same speaker may act very different, due to 50Hz wall power
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So you're certain that amplifiers (any electronic item, really) don't convert AC from the wall, into DC for use by its various components?
Plug a speaker into a wall outlet and let me know what you hear. :)
I've done that, it sounds very 60Hz-ish to me....
Call me old fashioned but that really limits the choice of key signature and gets monotonous. ;)
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Jeff, part of what I think you are missing (or making assumptions about) is that you need more fundamental pitch, which is relatively contrary to the way basses "speak". The 2nd and 3rd harmonics, right from the instrument, have a greater magnitude than the fundamental - by +10dB or more with many instruments - except for 1 or 2 hot spot notes, typically in the 60hZ and 80Hz area. If you play bass fiddle (double bass) or mix a band that uses one, you're probably acquainted with those hot spot notes as there are very, very few instruments that present an even output across the range.
Your double 18" cab will be strong on fundamental and weaker on harmonics (which will be very "beamy") and that will certainly impact the perceived sound of your instrument, making it less bass guitar-like. If that's your goal, read on...
Next, the idea that you'll be running this cabinet anywhere close to those mythical power handling numbers in just that.... a myth. As I pointed out much earlier in this thread such operation will certainly result in the destruction of the speakers either from thermal failure or mechanical failure. Here's a hint: on EDM shows, with subwoofers rated higher than yours, I've found the maximum power they can safely dissipate over the long term is somewhere around 500W or so, and at that power it's difficult to keep the subs from dancing around on the floor.
Finally, there's a reason club/bar/small venue mixerpersons don't add much (if any) bass or guitars to a mix - they're already too fucking loud and he/she is having to mix UP to those levels for there to be any hope of a balanced mix. Your solution only makes this worse. I don't think you'll be able to alter the practices and expectations of those with whom you perform, but realize that playing "Keeping Up With the Marshalls" does not serve the interests of you, the audience or the mixerperson in these kinds of venues.
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I don't think so. I'm not an electrical engineer but have a basic understanding of electronics. AC volts from the wall don't convert to the DC voltage applied by the amp to the speaker by simply using Ohms Law. There's the conversion of AC wall power to the DC power used by speakers, the ability of the amp to store voltage, varying duty cycle (Even at full power, there are times during the signal no current is being given.) Varying resistance of the load (Speakers vary resistance by frequency) Amplifier efficiency/power lost, etc.
In short, my understanding is that consumer level amps like this can, in fact, deliver what they say they deliver from AC 12V 20A circuits. There are of course amps (Powersoft K20) which can only deliver their maximum with greater AC supply Voltage/Current, and plainly say so in their literature, but they will do far more than 6KW.
Huh? In an earlier post you said you understand that watts is watts. The second law of thermodynamics says that energy can neither be created nor destroyed. A 20A 120 VAC circuit is capable of supplying a continuous 2400 watts (somewhat more in short bursts depending on how bad you want to start a fire). Where does the other 3600 watts of energy come from??
Watts is calculated as volts X amps. Almost always when talking AC we assume "RMS" voltages-which is the voltage at which volts X amps gives the same result as it does for DC volts. It really is that simple. (OK so the math behind "RMS" is a little more compex and theoritical-but no need to go there.)
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Is this you?
https://youtu.be/esV0XlJYwN4 (https://youtu.be/esV0XlJYwN4)
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Coupled with the fact that most of the sound guys at this level put zero bass in the mix.
So we are here nonchalantly discussing a 6000W backline rig?!
(-The 70's just called, they want their Wall-o-SVT's back.)
Meanwhile, If I walked into mix some night and the visiting band's bassist had that much level then I sure wouldn't be putting much bass in the mix either!
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I am confused. Do you like what your rig sounds like, but just want it louder? Or, do you want something that sounds different?
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Jeff, part of what I think you are missing (or making assumptions about) is that you need more fundamental pitch, which is relatively contrary to the way basses "speak". The 2nd and 3rd harmonics, right from the instrument, have a greater magnitude than the fundamental - by +10dB or more with many instruments - except for 1 or 2 hot spot notes, typically in the 60hZ and 80Hz area. If you play bass fiddle (double bass) or mix a band that uses one, you're probably acquainted with those hot spot notes as there are very, very few instruments that present an even output across the range.
Yes, in fact with my current rig, I have everything below 60Hz rolled off. And at volume, still, can't make sound cleanly. Don't get me wrong, I'm making 60, 80 Hz etc., really loud with dual 15's. - But not cleanly. What most guys think sounds great from their SWR rigs or whatever they've spent $8K on from guitar center, certainly make those low notes loudly, but their lack of linearity sounds like doo-doo to me.
And yes, I know - most of what makes those instruments sound like what they do is not in their note's fundamental frequencies but in the harmonic content of those notes.Your double 18" cab will be strong on fundamental and weaker on harmonics (which will be very "beamy") and that will certainly impact the perceived sound of your instrument, making it less bass guitar-like.
Well, to a point, Even a dual 18 such as mine begins to roll off sharply at around 40 Hz. A 5-string's low B fundamental is around 30 Hz.Next, the idea that you'll be running this cabinet anywhere close to those mythical power handling numbers in just that.... a myth. As I pointed out much earlier in this thread such operation will certainly result in the destruction of the speakers either from thermal failure or mechanical failure. Here's a hint: on EDM shows, with subwoofers rated higher than yours, I've found the maximum power they can safely dissipate over the long term is somewhere around 500W or so, and at that power it's difficult to keep the subs from dancing around on the floor.
Yes, I think that's right where a continuous signal is concerned, like a sine (an EDM sample loop), or heavily compressed pre-recorded music. But reproducing momentary transients from a live instrument will need quite a bit more for fractions of a second. But so long as the average duty cycle stays around where you're talking about we're fine.Finally, there's a reason club/bar/small venue mixerpersons don't add much (if any) bass or guitars to a mix - they're already too fucking loud and he/she is having to mix UP to those levels for there to be any hope of a balanced mix. Your solution only makes this worse. I don't think you'll be able to alter the practices and expectations of those with whom you perform, but realize that playing "Keeping Up With the Marshalls" does not serve the interests of you, the audience or the mixerperson in these kinds of venues.
Believe me, I have fought this war for 30 years now. Everything you're saying I'm well aware of, both from a musician's point of view and that of a sound engineer. It's that I want to make low frequencies very, very cleanly. With no boom, overhang or other sounds that shouldn't be there. It's also that in many (not all, with some guys I only need to bring my little IEM rig, because I know they have the PA rig, engineering ability, and the ears to mix a band well) clubs, I can literally walk up to the stage, ears bleeding from guitar, drums and vocals, and literally can't tell what the bass player (and usually the keyboard guy, etc. ) are playing. Even if I know what the bass line is. Yes, it's all stage volume, and in an ideal world, we'd have Mr. drummer behind glass, and Mr guitar players playing through a 20-watt combo head - also behind glass. But, we're far from ideal in live rock band clubs. People pay, drink, it sounds loud and bad, and we get paid. It's just the nature of the beast, and change is difficult for guys who've been doing it that way for decades.
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Huh? In an earlier post you said you understand that watts is watts.
Yes - from the output of an amplifier. The second law of thermodynamics says that energy can neither be created nor destroyed.
Yes - but converting it from one form to another, like electrical to acoustic or even electrical AC to DC then back to AC, is never done in a 100% efficient manner. Some is lost in heat for example.A 20A 120 VAC circuit is capable of supplying a continuous 2400 watts (somewhat more in short bursts depending on how bad you want to start a fire).
Yes.Where does the other 3600 watts of energy come from??
I dunno, ask Crown, or QSC, or Crest, or any of the others who somehow, magically, apparently, are making more than 2,400 watts of power to a speaker from such a circuit.Watts is calculated as volts X amps.
Yes.Almost always when talking AC we assume "RMS" voltages-which is the voltage at which volts X amps gives the same result as it does for DC volts.It really is that simple.
No, it isn't. the varying impedance of a speaker load vs. frequency, for instance.
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Is this you?
Perhaps.
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So we are here nonchalantly discussing a 6000W backline rig?!
Yes, obscene, isn't it? :)(-The 70's just called, they want their Wall-o-SVT's back.)
A perfect example of a large, expensive and very loud rig - which sounds like doo-doo at any level above about 80dB.Meanwhile, If I walked into mix some night and the visiting band's bassist had that much level then I sure wouldn't be putting much bass in the mix either!
Where I live, ANY bass in the mix is a bad thing at the club and small theater level. It's a smug joke amongst these guys, who are STILL stuck in clubs despite spending many years learning their craft and wondering why...My unabashedly selfish goal is to take that decision out of his hands in such an event. Other times when I have a competent engineer, it's simply to reproduce my lows VERY cleanly, but not at mix destroying volumes.
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I am confused. Do you like what your rig sounds like,
Kinda, until it goes beyond rehearsal volume - say 90-100dBbut just want it louder?
I want lower, to be louder, and more accurate. The rest of my rig (my mid/high unit begins at about 80-100 Hz.) sounds great, even at loud stage volumes.Or, do you want something that sounds different?
Yes.
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As I said before, I've wrestled with this topic for many years. This rig is not the end-all for me. My preference is to use my IEM's only, with no noisemaker of any kind on stage. If I'm at a big venue or outdoor event where I know the sound company is up to snuff, this is what I do. Other bands I work with play in hard rock joints. It's mostly stage volume, and mostly sounds terrible, but that formula is what it is and there's no changing it. People drink, yell, and dance. And we get paid. I get tired of playing, knowing that the only person in the room who hears me is me. Or if they do, it's this foul, muddy non-descript mess from an underpowered, crappy system with an engineer who plain doesn't know what he's doing. If it's going to be mostly stage volume like that, mine will at least be good and clean.
I guess my impetus is that my 'day gig' so to speak is working for a couple of large sound companies as the backline tech and monitor Engineer. My 'best' company uses a Clair Bros rig with obscenely overkill amounts of power going to each of many subs. (Think twelve thousand watts to each dual 18 box, and yes, 90% of the time, only a small fraction of that is in use.) Even at very low, pre-show or background music levels, to stand next to these (or even better, to play through them after soundchecks) and hear what my instrument is capable of sounding like - really clear, clean deep bass, is a beautiful thing. And we wantses it for ourselves. It doesn't necessarily have to be loud, but even so, my experience is that there's no substitute for big boxes with gobs of power to make really low sound like it should.
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double post deleted
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It used to be that Crown set the gold standard across the board. One of their big selling points was that they guaranteed that an amp would put out a minimum of X watts, from 20-20KHz continuously.
Fast forward to now, their top-end stuff is competitive, but others have bested even that. In the DJ and small PA market, we have the XTi series. I have an XTi 4000 for mids, and am pretty happy with it. About 3KW, and DSP for a good price. But - the specs aren't measured as they once were.
Anyhow, I'm thinking of an XTi 6002 for a dual 18" sub I just built. The XTi specifies 6,000 watts - BUT ONLY AT 1 kHz! What does this mean? Is my amp only going to do 3,000 watts at 40 Hz where I need it? Am I getting gypped and ought to shop for something else?
Has anyone measured or know the math on what these amps will 'really' do in a musical spectrum range? What will an XTi 6002 put out continuously from 30 Hz to 100 Hz?
I have read this thread twice now. To me it sounds as if you two end goals one of which I agree with and one of which I don't. I think your first goal is tone related not power related. ie Help me figure out how to get the tone I want to get from my set up regardless of volume. I think that your second goal is I am going to be playing at a high db level and need my systems tone to hold together.
My thoughts on your first solution, ie tone. I have used the XTi line for years along with the I-Tech and the MacroTech I series. You should be able to use the internal EQ/comp to create a patch that sounds the way you want it to sound when you are playing at a reasonable level. If I were near you I would be willing to come help you do this since I have done this for several other people here and on the Crown forum. This patch can only be achieve by having your rig set-up and working with the feature of the amp ie EQ/Comp to get the sound that you prefer. Once you have your tone and volume set for this patch the next part will be relatively easy. Save your preset.
Second part volume and what I would say is much to much for a small stage from your description. Get the rig to the volume that you want to play and copy the preset you just made to a second preset and use the second preset to fine tune your eq using the EQ/Comp on the XTi. Save the second preset.
You know have a preset that gives you the tone you want for shows around 90 db and you have one for shows where you are playing 100 db plus. Depending on which show you are playing use the appropriate preset. Use the tools you have to their fullest.
Just so you know and not to be a dick about it, if you show up on one of my stage to play as loud as you are talking about here, you will turn down. That is not an opinion that is a fact. We are hired by festivals to meet their expectations of sound not by the bands who happen to be playing the festival. Now if your band wants to hire me and be as loud as you are talking about being then, we will pass on the show. Stage loud doesn't equate to good. Yes your friends with their Marshals will be turning down.
Bill
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I have read this thread twice now. To me it sounds as if you two end goals one of which I agree with and one of which I don't. I think your first goal is tone related not power related. ie Help me figure out how to get the tone I want to get from my set up regardless of volume. I think that your second goal is I am going to be playing at a high db level and need my systems tone to hold together.
My thoughts on your first solution, ie tone. I have used the XTi line for years along with the I-Tech and the MacroTech I series. You should be able to use the internal EQ/comp to create a patch that sounds the way you want it to sound when you are playing at a reasonable level. If I were near you I would be willing to come help you do this since I have done this for several other people here and on the Crown forum. This patch can only be achieve by having your rig set-up and working with the feature of the amp ie EQ/Comp to get the sound that you prefer. Once you have your tone and volume set for this patch the next part will be relatively easy. Save your preset.
Second part volume and what I would say is much to much for a small stage from your description. Get the rig to the volume that you want to play and copy the preset you just made to a second preset and use the second preset to fine tune your eq using the EQ/Comp on the XTi. Save the second preset.
You know have a preset that gives you the tone you want for shows around 90 db and you have one for shows where you are playing 100 db plus. Depending on which show you are playing use the appropriate preset. Use the tools you have to their fullest.
Just so you know and not to be a dick about it, if you show up on one of my stage to play as loud as you are talking about here, you will turn down. That is not an opinion that is a fact. We are hired by festivals to meet their expectations of sound not by the bands who happen to be playing the festival. Now if your band wants to hire me and be as loud as you are talking about being then, we will pass on the show. Stage loud doesn't equate to good. Yes your friends with their Marshals will be turning down.
Bill
Hey Bill, thank you for your excellent reply - you understand fully what I'm going to do. Just because I HAVE the tool, doesn't mean I have to USE it at full capacity.
My ambition was exactly as you've stated. I'll have my "We're outdoors in front of 3K people but only small wedges onstage, so I can go low - loud" preset, and my "small room, but I can go really low and be super clean and accurate/linear" preset. Many others are possible too, like my "mid-size hard-rock oom, but substitute PA guy is a guitar player friend of the guitar player's and views bass as a nuisance" preset :)
This is a reason I need onboard DSP and can't save on an older but probably good as new Macro-Tech, etc.
Secondly, I wouldn't need to show up at your venue and be the dick musician who wants to kill your mix - because it sounds like you actually know what you're doing. Most "Sound Engineers" in clubs do NOT. My favorite way to play is using IEM's only - it's just the way modern sound is built. I even offer to provide an IEM rig for everyone. Sadly, it hasn't become universally understood.
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So we are here nonchalantly discussing a 6000W backline rig?!
(-The 70's just called, they want their Wall-o-SVT's back.)
Meanwhile, If I walked into mix some night and the visiting band's bassist had that much level then I sure wouldn't be putting much bass in the mix either!
Chicken and egg scenario. ;D
An SVT 810 rolls off around 60Hz if I recall correctly, I've never heard any missing notes on a 5 string bass.
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Chicken and egg scenario. ;D
An SVT 810 rolls off around 60Hz if I recall correctly, I've never heard any missing notes on a 5 string bass.
You won't hear missing notes, because the second harmonic dominates. You also won't hear the 31 Hz low B fundamental, as the 12 dB per octave roll off of the sealed SVT puts the fundamental an additional 12 dB down from what it could be.
A bass player can't compete with the mid-bass of drums and Marshall stacks without further muddying up the mix in a small room, but playing loud clean fundamentals allows them to hear (and feel) the fundamentals without needing to kill in the low-mid to compete.
Art
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[DC has no "frequency".
[/quote]
DC has frequyency of 0Hz ;)
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[DC has no "frequency".
DC has frequyency of 0Hz ;)
Frequency means "cycles".
Zero in this case is not a number, but rather a meaning of "nothing".
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[DC has no "frequency".
DC has frequyency of 0Hz ;)
Is -60hz just 60hz 180 deg out of phase?
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Is -60hz just 60hz 180 deg out of phase?
How do you have less than zero cycles?
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You won't hear missing notes, because the second harmonic dominates. You also won't hear the 31 Hz low B fundamental, as the 12 dB per octave roll off of the sealed SVT puts the fundamental an additional 12 dB down from what it could be.
I've found that this can vary depending on the instrument, player and even more importantly...the playing technique being utilized.
I have played my bass DI'd (Radial JDV) into my mixer and utilized the onboard RTA to see what frequencies dominate. Fingerstyle playing tends to have an emphasis on the 2nd harmonic with the fundamental varying from -3 to -10db. A double thumb technique actually flips that and the fundamental is up over the harmonics by at least 3db.
A bass player can't compete with the mid-bass of drums and Marshall stacks without further muddying up the mix in a small room, but playing loud clean fundamentals allows them to hear (and feel) the fundamentals without needing to kill in the low-mid to compete.
Art
The "and feel" part is where most non-bass players (and even some bass players) miss the boat. Feeling the "sonic weight" of the fundamental can be critical with some playing styles. For me it's as important as being able to hear my natural voice clearly in the monitors to be able to sing well. As well as I can sing, anyway.
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How do you have less than zero cycles?
The same way you have less that zero money? ;)
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You won't hear missing notes, because the second harmonic dominates. You also won't hear the 31 Hz low B fundamental, as the 12 dB per octave roll off of the sealed SVT puts the fundamental an additional 12 dB down from what it could be.
A bass player can't compete with the mid-bass of drums and Marshall stacks without further muddying up the mix in a small room, but playing loud clean fundamentals allows them to hear (and feel) the fundamentals without needing to kill in the low-mid to compete.
Art
Bingo. We have a wiener.
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A bass player can't compete with the mid-bass of drums and Marshall stacks without further muddying up the mix in a small room, but playing loud clean fundamentals allows them to hear (and feel) the fundamentals without needing to kill in the low-mid to compete.
Art
This. A thousand times - this. Thank you, Art Welter.
It may seem paradoxical, but this rig will allow my bass and other members' guitars drums live together more harmoniously. If anything, now I can play at less 'volume' and yet still 'hear' and 'feel' more.
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The "and feel" part is where most non-bass players (and even some bass players) miss the boat. Feeling the "sonic weight" of the fundamental can be critical with some playing styles. For me it's as important as being able to hear my natural voice clearly in the monitors to be able to sing well. As well as I can sing, anyway.
Many people feel this way (pun intended). It took me about twenty gigs to get used to playing with IEM's only, but once I really got it, I can assure you that you can play just as effectively with nothing other than ear monitors. Think about studio - most guys just record with a pair of cans, myself included.
It's nice to 'feel,' but not necessary. Still, where the circumstances allow, I will have my new box there, because feeling it is fun!
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Incidentally, I did end up going with an XTi 6002. I got a smokin' deal on a brand new with warranty one at a used price. I'm also quite confident now that it will provide all I'll ever need, even with this Goliath, so thank you all for the insights and opinions.
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Within the last year I've moved to in ears for monitoring as well, and it's been fantastic. But in a live band situation I still need to feel some air moving from my rig in order to be comfortable and play my best. I suspect that the ultimate solution for me is to get a shaker platform like the Tecamp Bass Board.
Studio playing seems to be completely different from my perspective. I've done the vast majority of recording with just headphones, but I'm not directly adjacent to a loud drummer and guitarist like I am in a live situation. For me it boils down to whether I can 'feel' what I'm playing over what other's are playing.
Keep us posted on how the amp works out. I've moved to micro amps nowadays but for almost 20 years my live rig was a Demeter tube preamp and a Crown Macrotech 2402. ~1500watts bridged into 4 - 12" cabs. Headroom is a beautiful thing.
(https://images.talkbass.com/attachments/completer2-jpg.1565296/)
Many people feel this way (pun intended). It took me about twenty gigs to get used to playing with IEM's only, but once I really got it, I can assure you that you can play just as effectively with nothing other than ear monitors. Think about studio - most guys just record with a pair of cans, myself included.
It's nice to 'feel,' but not necessary. Still, where the circumstances allow, I will have my new box there, because feeling it is fun!
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Within the last year I've moved to in ears for monitoring as well, and it's been fantastic. But in a live band situation I still need to feel some air moving from my rig in order to be comfortable and play my best. I suspect that the ultimate solution for me is to get a shaker platform like the Tecamp Bass Board.
Studio playing seems to be completely different from my perspective. I've done the vast majority of recording with just headphones, but I'm not directly adjacent to a loud drummer and guitarist like I am in a live situation. For me it boils down to whether I can 'feel' what I'm playing over what other's are playing.
Keep us posted on how the amp works out. I've moved to micro amps nowadays but for almost 20 years my live rig was a Demeter tube preamp and a Crown Macrotech 2402. ~1500watts bridged into 4 - 12" cabs. Headroom is a beautiful thing.
(https://images.talkbass.com/attachments/completer2-jpg.1565296/)
Your tube amp mounted crooked in that amp is making me angry.
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Your tube amp mounted crooked in that amp is making me angry.
Haha. Yeah, that preamp was annoying. Apparently Demeter made an entire batch of that model using the same rack ear on both sides (making one side "upside down"), so utilizing all four bolt holes meant mounting it into the rack crooked. I did drill an extra hole in the "wrong" rack ear but that meant I could only utilize three holes to mount it, which I sometimes did.
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DC has frequyency of 0Hz ;)
This is correct. Furthermore, for real (not complex) signals, as we usually encounter here, the response to negative frequencies is the complex conjugate of that to positive frequencies, mirrored around zero frequency. For example, a low-pass filter has a symmetrical magnitude response centered on zero frequency. My point is that we can't really talk about frequency rigorously without accepting the idea of negative (and zero) frequency.
If we want the response to negative frequencies to be zero we require an analytic signal, which has the property that its real and imaginary parts are related by a Hilbert transform. In any case, it's complex, not real, and as such needs to by represented by two real signals.
--Frank
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Haha. Yeah, that preamp was annoying. Apparently Demeter made an entire batch of that model using the same rack ear on both sides (making one side "upside down"), so utilizing all four bolt holes meant mounting it into the rack crooked. I did drill an extra hole in the "wrong" rack ear but that meant I could only utilize three holes to mount it, which I sometimes did.
Interesting that they won't fix their mistake.
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So, I built the box and it sounds great. I would like to tune a bit lower as it has more than enough volume capability already.
Doing so requires extending my ports by 8 inches. I'll still have about 4 inches or so of clearance to the back. The clearance area from the rear of the ports will still have a larger area than the cross-section of the ports themselves by a good margin (about 200 sq. in. vs. 185 sq. in.).
Question, is that enough room to avoid audible artifacts like "chuffing"? My WinISD program seems to indicate no appreciable difference in rear port turbulence.
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So, I built the box and it sounds great. I would like to tune a bit lower as it has more than enough volume capability already.
Doing so requires extending my ports by 8 inches. I'll still have about 4 inches or so of clearance to the back. The clearance area from the rear of the ports will still have a larger area than the cross-section of the ports themselves by a good margin (about 200 sq. in. vs. 185 sq. in.).
Question, is that enough room to avoid audible artifacts like "chuffing"? My WinISD program seems to indicate no appreciable difference in rear port turbulence.
WinISD's calculations for port length and air velocity assume you will keep the back end of the vent at least one diameter away from the back wall of the box.
That means the back of your 185 sq in port needs to be at least 15(& a little bit)" away from the box rear wall otherwise you can't necessarily trust the predicted tunings and airspeeds will be correct.
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Before it was 12" from the rear, with driver mechanical noise being louder than any chuff I heard, and that was below Fb anyway. The box is already deeper (30") than I'd like, so extending that wasn't an option. Adding elbows seemed to have its own set of issues with turbulence from what I read. Flares weren't really an option either unless I wanted to go with circles, which would require a much larger box to get the same port area.
I added the port lengths yesterday, now I have 3.5 inches of clearance X2 ports. The area of clearance is now 172 Sq. in. I guess we'll see what happens and how it sounds, where the Fb is, etc. today. Some chuff with a sine near the X-max doesn't concern me, it's a question of whether the noise will audibly effect my real-world conditions. Right now the trade-off for ideal port performance vs. being able to hit a low 'B' (31 Hz) cleanly, and within 3dB is acceptable. I can always pry 'em off and go shorter.
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Haha. Yeah, that preamp was annoying. Apparently Demeter made an entire batch of that model using the same rack ear on both sides (making one side "upside down"), so utilizing all four bolt holes meant mounting it into the rack crooked. I did drill an extra hole in the "wrong" rack ear but that meant I could only utilize three holes to mount it, which I sometimes did.
Every set of rack rails I have worked with is symmetrical - there is no "left" and "right" set. A 1U chunk of normal rack rail has a high, low, and middle hole. Cutting rack rail is done between the upper hole of the lower "U" and the lower hole of the upper "U", and then any piece is interchangeable.
What your rack manufacturer did was to either cut the rail wrong, or mount it wrong.
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Haha. Yeah, that preamp was annoying. Apparently Demeter made an entire batch of that model using the same rack ear on both sides (making one side "upside down"), so utilizing all four bolt holes meant mounting it into the rack crooked. I did drill an extra hole in the "wrong" rack ear but that meant I could only utilize three holes to mount it, which I sometimes did.
Maybe it's just the angle of the picture but to me the pre amp does not look to be a standard rack space sized unit, with the amp as a reference the pre amp look like it may be something like a space and a half tall.
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WinISD's calculations for port length and air velocity assume you will keep the back end of the vent at least one diameter away from the back wall of the box.
That means the back of your 185 sq in port needs to be at least 15(& a little bit)" away from the box rear wall otherwise you can't necessarily trust the predicted tunings and airspeeds will be correct.
So, with the new port extensions, it RAISED my Fb! (???) I was at about 38-39, now at about 43? Subjectively it sounds smoother and less 'peak-y.' Seems to be 'deeper.' There is LESS chuff or mechanical noise than before. IOW, it sounds better. I'm at a total loss to explain why the Fb went up instead of to 32 Hz. All I can guess is that maybe 30 Hz needs much more excursion than 40 Hz and that makes up for Fb (???) Maybe my sweep isn't linear?
It still gets floppy below 30Hz but seems to stand up otherwise. My low 'b' is strong...
I'm very confused.
Setting the Qp in the advanced box tab of WinISD at any value doesn't duplicate this. Even a one (default is 100) doesn't produce this result.
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So, with the new port extensions, it RAISED my Fb! (???) I was at about 38-39, now at about 43? Subjectively it sounds smoother and less 'peak-y.' Seems to be 'deeper.' There is LESS chuff or mechanical noise than before. IOW, it sounds better. I'm at a total loss to explain why the Fb went up instead of to 32 Hz. All I can guess is that maybe 30 Hz needs much more excursion than 40 Hz and that makes up for Fb (???) Maybe my sweep isn't linear?
It still gets floppy below 30Hz but seems to stand up otherwise. My low 'b' is strong...
I'm very confused.
Setting the Qp in the advanced box tab of WinISD at any value doesn't duplicate this. Even a one (default is 100) doesn't produce this result.
Well, it's got to be some kind of artifact of the port end being close to the back wall of the box, but I don't know an exact mechanism to explain how.
If you like the result though, and it's not introducing any worse port noise etc than the previous version, then just enjoy it ;-)
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Well, it's got to be some kind of artifact of the port end being close to the back wall of the box, but I don't know an exact mechanism to explain how.
If you like the result though, and it's not introducing any worse port noise etc than the previous version, then just enjoy it ;-)
Part of me agrees, and part of me wants to know why it seems to defy the laws of physics. Is there a different way to determine resonance than watching a dot on the cone?
Maybe my test is fouled somehow... I can't imagine how something with such oversized ports like this which still has 4 inches of clearance behind them can do this.
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Part of me agrees, and part of me wants to know why it seems to defy the laws of physics.
I highly doubt that it is defying the laws of physics. However, it may well be defying your understanding of the laws of physics.
Is there a different way to determine resonance than watching a dot on the cone?
I like to measure the impedance curve of a loudspeaker driver and the driver in the cabinet. You could also measure the impedance curve with and without your port extensions in place to see the difference they are actually making.
Maybe my test is fouled somehow... I can't imagine how something with such oversized ports like this which still has 4 inches of clearance behind them can do this.
It has already been mentioned, more than once, that the distance between the port and the back of the cabinet should be at MINIMUM the diameter of the port plus a little more. In fact, it should be more than this distance. If your port is larger than 4" and the back of the port is approximately 4" from the back of the cabinet, you are already too close for optimum operation. This is the truth, regardless what you think is right.
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FWIW, and it's probably just because I didn't learn WinISD well enough, but I couldn't get WinISD to model ported boxes with the same results as Hornresp or Jeff Bagby's spreadsheet.
Those two gave similar results, so I went with them ...and measurements ended up matching the sims..
I had the same concern about box depth vs port length.
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I highly doubt that it is defying the laws of physics. However, it may well be defying your understanding of the laws of physics.
Key word = 'seems' but I hear what you're saying.I like to measure the impedance curve of a loudspeaker driver and the driver in the cabinet. You could also measure the impedance curve with and without your port extensions in place to see the difference they are actually making.
Do I need special tools, or can this be done with my multimeter?It has already been mentioned, more than once, that the distance between the port and the back of the cabinet should be at MINIMUM the diameter of the port plus a little more. In fact, it should be more than this distance. If your port is larger than 4" and the back of the port is approximately 4" from the back of the cabinet, you are already too close for optimum operation. This is the truth, regardless what you think is right.
I will need to either break/pry the extensions off completely or maybe get a saw in there and cut a couple inches off. Does it have something to do with how the air enters and leaves rather than velocity?
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Key word = 'seems' but I hear what you're saying.Do I need special tools, or can this be done with my multimeter? I will need to either break/pry the extensions off completely or maybe get a saw in there and cut a couple inches off. Does it have something to do with how the air enters and leaves rather than velocity?
Interesting. Would you want to input the specs on my design and see what you come up with? Obviously, it won't matter in the real world with the ports I've just added, because I can see the results for myself. At this point, I'm just trying to figure out how to tune as low as possible with what I have available in this box.
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Do I need special tools, or can this be done with my multimeter?
Most dual channel audio measurement platforms offer this feature. I feel it is generally underutilized by many folks as it is extremely useful.
Audio Tools with the iAudioInterface can do it on the iOS platform
The Terrasonde Audio Toolbox (http://www.audiotoolbox.us) is fully capable as well
Smaart with a dual channel interface plus impedance box on a PC or Mac platform
TEF can do it for sure, though I'm not sure of the particulars
I would expect that SIM and EASERA can do it too, but I'm not as familiar with them.
If you are looking for a low cost way to get it done and you are an avid DIY loudspeaker guy, you really should have one of these Parts Express DATS interfaces (https://www.parts-express.com/dayton-audio-dats-v2-computer-based-audio-component-test-system--390-806). These things are great for measuring drivers and assembled loudspeakers.
I will need to either break/pry the extensions off completely or maybe get a saw in there and cut a couple inches off. Does it have something to do with how the air enters and leaves rather than velocity?
I'm not totally certain, but I assume it has everything to do with how the pressure waves of the sound enter and leave the pipe, or how the air velocity in the pipe terminates at the ends of the pipe. I have never studied this in any kind of detail, I have always just made absolutely certain that there is at least the diameter of the port plus some between the end of the pipe and the back wall of the cabinet.
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Jeff Schoonover1 = SUPER genius.
Be sure both the Hi-Pass portion of the crossover and the Hi-Pass filters are disengaged before running resonance tests. I'm just that smart :)
Anyhow, now it works like the Win ISD model predicts. Fb is easy to see right at 29-30 Hz. The cones noticeably un-couple at anything significantly lower. I haven't gotten really loud yet, but there is no port noise at all so far.
So, now the big question. My EQ HP filter was set for 20Hz with a pretty sharp Q. I also had set the HP of the X-Over to BW 48 @ 27 Hz. I tried using both and separately when I was setting them up before. Yet, as I've just seen, these still interfered a lot with the response from my sub.
I know there's a curve above the set frequency, but I tried to minimize this as much as possible, by going a bit lower. Still, it had undesired effects.
I must protect from frequencies below resonance. I do a lot of thumb-popping, which will send a DC square wave at them if I'm not very careful. Even with lots of care, the thumb thing really abuses woofers.
Is it that the EQ and X-Over in the Crown XTi series is less than great? Should I set them lower? I need 31Hz, but need to protect from 20 Hz.