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Author Topic: 25 Hz is the new 50 Hz - ULTRA Music Festival  (Read 70968 times)

Ivan Beaver

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Re: 1W or 2.83V
« Reply #90 on: July 19, 2013, 06:10:20 AM »

While I can't disagree with you Brad, making the industry standard sensitivity rating one watt into it's rated Ohms would level the playing field when it comes to comparing apples to apples.

Imagine if a car wasn't rated in maximum miles per hour but instead fast, faster or plaid. How do you compare?
The problem is that you CANNOT put 1 Watt into a loudspeaker-but you CAN put 2.83V.

Because the impedance of a loudspeaker is all over the map-if you did put 1watt (at all freq) then the freq response would be all over the place.

The best that you can do is to apply a voltage that is equal to 1 watt at some impedance-usually the rated impedance.

HOWEVER- the actual impedance is going to be higher and lower-meaning that depending on freq there will more or less than 1 watt actually being dissapted by the loudspeaker.

But if you apply a standard voltage (say 2.84V) then that will remain constant.  And since we do not apply wattage to a loudspeaker-but rather voltae-to me it just makes more sense to use a standard voltage as the test input.

Yes the user has to do A LITTLE BIT OF THOUGHT (which sadly seems to be lacking these days ;(  ) to get comparative numbers.  HOWEVER in many cases you can't even begin to compare-because of the lack of USABLE data-such as a simple freq response WITHOUT eq. 

Without that=you have NO IDEA where the 'sensitivity" number came from-or if it was even in the intended passband of the device.

And once you start to add "manufacturer suggested eq" it all starts to fall apart-ESPECIALLY on subs where it seems popular to simply add a boost on the low freq to make it appear to go lower.

HOWEVER this not only increases the input voltage-but also the wattage-so the whole idea of "1 watt" or a constant voltage falls apart.

This can work at low levels-but when you start to push a sub that has a low freq boost-it will quickly "run out of gas" when it gets loud-and at the freq where the boost was added-it simply won't get as loud.

But hey-let's just ignore that fact and look at the simple number and try to make a "rational" decision-based on some unknown facts.

Just like a court case in which a lawyer simply makes up "facts" until somebody challenges him-he can make the case go his way-----------------
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

paul bell

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Re: 1W or 2.83V
« Reply #91 on: July 19, 2013, 07:48:35 AM »

Good morning Ivan!

I understand what is being said here. Yes, different speakers will consume one watt at different frequencies.

So then how can the discerning buyer compare speakers on a level playing field?

Perhaps our friends at McCauley have it right, they list 2.83 volts AND the current drawn at the cabinet's nominal Ohm rating.

Here is a McCauley cabinet (the SA288 dual 18 sub) that can be had in 2 or 4 Ohms and the watts drawn are listed. Stating the watts drawn tells the buyer how to compare it to other cabinets.
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Brad Weber

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Re: 1W or 2.83V
« Reply #92 on: July 19, 2013, 08:13:04 AM »

While I can't disagree with you Brad, making the industry standard sensitivity rating one watt into it's rated Ohms would level the playing field when it comes to comparing apples to apples.
As Ivan explained, the 1 Watt sensitivity ratings and responses do not actually represent the speaker being driven with 1 Watt but rather with the voltage equivalent to 1 Watt at some stated nominal impedance, which is itself typically a 'normalized' value of 16 Ohms, 8 Ohms, 4 Ohms or maybe 6 Ohms rather than the actual, and varying with frequency, impedance of the speaker.  Thus a sensitivity specified for 1 Watt is not actually related to 1 Watt into the speaker, it is instead related to a defined drive voltage (4V for 16 Ohms, 2.83V for 8 Ohms, 2.45V for 6 Ohms and 2V for 4 Ohms).
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paul bell

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Re: 1W or 2.83V
« Reply #93 on: July 19, 2013, 08:30:19 AM »

As Ivan explained, the 1 Watt sensitivity ratings and responses do not actually represent the speaker being driven with 1 Watt but rather with the voltage equivalent to 1 Watt at some stated nominal impedance, which is itself typically a 'normalized' value of 16 Ohms, 8 Ohms, 4 Ohms or maybe 6 Ohms rather than the actual, and varying with frequency, impedance of the speaker.  Thus a sensitivity specified for 1 Watt is not actually related to 1 Watt into the speaker, it is instead related to a defined drive voltage (4V for 16 Ohms, 2.83V for 8 Ohms, 2.45V for 6 Ohms and 2V for 4 Ohms).

YES MY POINT EXACTLY!

This is why a speaker's specified sensitivity should be rated using a input test voltage relative to it's rated Ohms.

A cabinet with a nominal 4 Ohms should be tested with an input voltage of 2 Volts, not 2.83 Volts.

Example: A guy goes shopping for a subwoofer. It has two 4 Ohm woofers resulting in it being a 2 Ohm cabinet. A salesman reading the specifications tells him this cabinet has a sensitivity of 104 Db. Then there's another cabinet shown that's a single 8 Ohm woofer cabinet with a sensitivity of 101 Db. How does the buyer know that the dual woofer cabinet is actually less sensitive than the single woofer cabinet?
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Ivan Beaver

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Re: 1W or 2.83V
« Reply #94 on: July 19, 2013, 01:11:30 PM »

YES MY POINT EXACTLY!

This is why a speaker's specified sensitivity should be rated using a input test voltage relative to it's rated Ohms.

A cabinet with a nominal 4 Ohms should be tested with an input voltage of 2 Volts, not 2.83 Volts.

Example: A guy goes shopping for a subwoofer. It has two 4 Ohm woofers resulting in it being a 2 Ohm cabinet. A salesman reading the specifications tells him this cabinet has a sensitivity of 104 Db. Then there's another cabinet shown that's a single 8 Ohm woofer cabinet with a sensitivity of 101 Db. How does the buyer know that the dual woofer cabinet is actually less sensitive than the single woofer cabinet?
So exactly how do you determine what the impedance really is?

Is it the lowest point (even if it is only a couple of Hz wide)? or an average (exactly how is that determined-over what freq range-linear or log freq? or is it the nearest standard value?

Many loudspeakers are rated as either 4-8-16 ohms-even though the load the present to the amp may not be that. Those are just the nearest standard values. 

You could come up with sorts of different "ideas" on the impedance and use they varying ideas to state a particular voltage (that would come out to 1 watt) and still provide very unrealistic sensitivity numbers.

lets say a speaker is rated for 8 ohm-which would be 2.83V.  But it has a peak in the impedance curve around 32 ohms-not uncommon.  So if you use that value to determine the voltage required for 1 watt you get 5.6V or a difference of 6dB.  So the "rating" would actually be 6dB higher than what the average person could get out of the speaker-if they applied a normal voltage.

You can "work" the numbers in all sorts of different ways-and they are not lying-but they are far from telling the truth or at least giving an idea of what the average person could reasonably expect out of a product.  But that doesn't stop some manufacturers--------------------------------

And believe me-if a manufacturer gives a number that is REALISTIC-but not a standard-it is the source for a lot of confusion.  just rate a speaker for 6 ohms and see what happens-----------------Many people have no idea what amp to buy since they don't see a 6 ohm rating.------------------------

A slightly educated person can read the sensitivity graphs and the impedance graph (assuming that it is provided-which is becoming less and less-as I feel manufacturers are trying to "hide" things) and get an idea if the loudspeaker will do the job for them.  They also need to see the "presets" curve it presets are part of the spec sheet.

EAW has done a good job of this-showing the raw response-preset curve and a final curve.



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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Ivan Beaver

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Re: 1W or 2.83V
« Reply #95 on: July 19, 2013, 01:24:02 PM »

And just to "further complicate" things without a measured freq response GRAPH-there is no way to know where the stated sensitivity )be it voltage or power) is coming from.

I know a number of cases in which the sensitivity  (max output) is stated as 10dB (or more) higher than a normal person could get out of the cabinet-because there is a peak in the response that makes it really loud.

So the "casual" person would see this and say-OH that cabinet can do 140dB-it is much louder than the other one that can only do 135dB.

But if you look at the response-that 140dB number comes from a single peak that has to be eqed down to match the rest of the cabinet-and NOW the AVERAGE response is 130dB-so it is really not as loud-but they made a sale from it.

Is the manufacturer lying-NO-it will produce that SPL at "SOME" freq-but not across the usable freq range.  But the number is VERY misleading to people who either don't know better-or because the manufacturer did not provide a response graph to look at.
 
SO KNOW WHERE THE NUMBERS COME FROM-and DON'T just look at the single simple numbers on a spec sheet.

If you want a real answer-you have to dig a little deeper.

But sadly it seems that the current trend of some very expensive loudspeakers give no specs at all.  I guess this means that nobody can say it doesn't meet spec-because there are none------------------------------------
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A complex question is easily answered by a simple-easy to understand WRONG answer!

Ivan Beaver
Danley Sound Labs

PHYSICS- NOT FADS!

Keith Broughton

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Re: 1W or 2.83V
« Reply #96 on: July 19, 2013, 04:04:27 PM »

Quote
But sadly it seems that the current trend of some very expensive loudspeakers give no specs at all.  I guess this means that nobody can say it doesn't meet spec-because there are none------------------------------------
Like the customer who asked the Rolls Royce salesman "how much power does this engine produce?"
"Sufficient" was the answer.
It seems these days that more manufacturers want to use the black-box-it-will-work-fine concept and keep  consumers away from those pesky facts!
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I don't care enough to be apathetic

Anton Tumas

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Re: 25 Hz is the new 50 Hz - ULTRA Music Festival
« Reply #97 on: October 15, 2013, 09:13:24 PM »

I have heard those Danley TH221s at an outdoor event, and they give a big round bottom to the sound, with a very full feeling. The other most impressive subs I have heard have been d&b B2 ground stacked 3 per side. That was gut wrenching.
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Danley Sound Labs TH118, SH46 and SM80 via XTA DP448

Mac Kerr

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« Reply #98 on: October 15, 2013, 09:17:22 PM »

I have heard those Danley TH221s

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 in the Forum Announcements section, and on the registration page when you registered.

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Lee Buckalew

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Re: 25 Hz is the new 50 Hz - ULTRA Music Festival
« Reply #99 on: November 18, 2013, 02:26:48 PM »

As i am aware of all the active ASX that Martin have sold including the Ministry of sound) has been downgraded to passive due to very poor reliability of the Ipal combo. And as i have heard the active ASX has been discontinued till further notice.

Wanted to reply to this and set the record straight as I am working on a project where I am investigating the ASX as an option. 
I checked with Martin and was told that not only have none of the ASX at the MoS been changed to passive but all remain as originally designed.  There has recently been a design change to the BC drivers, all at MoS have been upgraded.  They were just upgraded within the last two weeks.  Since the install MoS has had one ASX with an amplifier issue, this was 3 years ago.  They have had no problems before or since with amp modules.

MoS has also won the award for "Best Global Club Sound" 4 years running.  During this time the ASX have all been actively powered, as designed.

Lee
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Lee Buckalew
Pro Sound Advice, Inc.

ProSoundWeb Community

Re: 25 Hz is the new 50 Hz - ULTRA Music Festival
« Reply #99 on: November 18, 2013, 02:26:48 PM »


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