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Author Topic: Rcf 8006 and 9006  (Read 2845 times)

Mark Wilkinson

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Re: Rcf 8006 and 9006
« Reply #40 on: October 03, 2018, 12:22:05 pm »

This is a good example of where the data from engineering gets entered wrong by others.

Thanks for the heads up-I have already passed the error onto the "parties that be" to be changed.


You bet Ivan,

I second the John S appreciation for the response curves you guys provide.

I guess the engineer in me is always looking for more hard data that's truly comparable.
 
FWIW, I'd rate Fulcrum's specs as the most useful I've seen.....
particularly because they show both raw and processed curves....
as well as polars/directivity and impedance curves.

Given how well your products would look under the same set of graphs, I often wonder why Danley doesn't show all those.
I guess in fairness, the install market looks more to modeling than specs?  for which you have Danley Direct



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Ivan Beaver

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Re: Rcf 8006 and 9006
« Reply #41 on: October 03, 2018, 01:05:08 pm »

...and if you measure it the same way as almost everyone else 102 dB w/m :)
OORRRRR  I fyou use the "1 watt" method-how DO you apply 1 watt to the loudspeaker at all freq?  You don't, you apply A VOLTAGE, and the power is calculated-based on some impedance.

So if you use the 1 watt method and use the impedance peak around 41Hz as your "standard", you get to add 4.77dB to the sensitivity.

That is EXACTLY why Danley uses 2.83V for ALL models.   No matter the impedance

It keeps the drive level the same
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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: Rcf 8006 and 9006
« Reply #42 on: October 03, 2018, 01:14:39 pm »

If RCF published frequency response graphs for the 8006 & 9006 perhaps there would be fewer requests from Labsters for the subjective opinions of others as to how they compare.  I particularly appreciate Ivan's remarks regarding how a frequency response graph allows us to make our own determination of the -3dB spec (or whatever) for a given sub.

The band I work for owns EV PX2181s.  They are an incarnation of EV's "horn-loaded sub-scoop" design.  The spec sheet lists them as -3db at 45Hz, but when I look at the chart (thank you EV), using the response from 60-90 as the reference, I conclude that the -3dB point is a bit higher than that.  That's helpful to me because one possible sub that I might buy is the ThMini 15 which has a -3dB spec of 50Hz which sounded too high to me until I looked up the actual response of the subs I mix on every week.

Unfortunately, almost none of the big boys publish the frequency response of their subs anymore.  A great illustration of this issue is the DVA S30n.  It has a published -3dB spec of 30Hz and a maximum output of 141dB.  Sounds great!  However, I found a Youtube review of the sub by TrinityProSound that includes some informal objective response information which makes it clear that this quasi-horn design has very limited response below 50Hz relative to the 60-90 range.  I have no idea how they can give it a -3dB rating of 30Hz based on what is shown in that video and we all must assume that the same thing is true for all of the other claimed responses that aren't backed up with object graphs.
There is one sub from a brand that gets mentioned here all the time.

It has a stated -3dB of 30Hz.  But on THEIR OWN GRAPH, the level at 30Hz is actually 27dB down from the rated sensitivity.

It must be that "new math" they are using.

People often forget that -3dB HAS NO MEANING WHAT SO EVER,  It can be ANYTHING somebody wants it to be.

It simply means that the particular freq is 3 dB lower than "something else".

If the "something else" is not stated, then the number is meaningless.

But in order to make some sort of sense, the -3dB SHOULD be 3dB down from the rated sensitivity.

SO a manufacturer can choose to have a higher rated sensitivity (at some peak freq) but they ALSO must accept a higher -3dB cutoff.

Or they can have a lower -3dB point, but then the rated sensitivity must also be lower.

That is why graphs are so important.  You can look at a graph and choose whatever numbers YOU feel are important, and not have to guess as to what the manufacturer was choosing for numbers.
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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!

Mike Pyle

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Re: Rcf 8006 and 9006
« Reply #43 on: October 03, 2018, 01:17:19 pm »

If RCF published frequency response graphs for the 8006 & 9006 perhaps there would be fewer requests from Labsters for the subjective opinions of others as to how they compare.  I particularly appreciate Ivan's remarks regarding how a frequency response graph allows us to make our own determination of the -3dB spec (or whatever) for a given sub....

They do publish charts. Being powered cabs these of course are post processing. They also would appear to have the lowpass at the 50Hz setting.

https://www.rcf.it/c/document_library/get_file?uuid=ccc1d690-e611-4484-920d-45bbd2aa5660&groupId=20195

https://www.rcf.it/c/document_library/get_file?uuid=96242f83-a0e2-47ec-a970-f70f5bbf33c8&groupId=20195
« Last Edit: October 03, 2018, 01:24:41 pm by Mike Pyle »
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Dealer For: JBL, Soundcraft, Crown, dbx, AKG, Yorkville, EV, QSC, RCF, FBT, Danley Sound Labs, Tannoy, Lab Gruppen, Powersoft, VTC, EAW, Allen & Heath, Ashly, APB, Denon, Rane, Audix, One Systems, OnPoint Audio, Presonus, K&M, Ultimate, Global Truss, Road Ready, SKB, Gator, Radial Engineering, Turbosound, Midas, dB Technologies, American DJ, Odyssey, ProCo, Rapco, CBI, Elation, Mipro, Chauvet, Blizzard, Shure, Whirlwind, BenQ, Bassboss, Yamaha, Line 6, Behringer, Whirlwind, On-Stage, more...

Taylor Hall

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Re: Rcf 8006 and 9006
« Reply #44 on: October 03, 2018, 01:37:37 pm »


That is why graphs are so important.  You can look at a graph and choose whatever numbers YOU feel are important, and not have to guess as to what the manufacturer was choosing for numbers.
Yet another way that the auto industry and the pro audio world overlap. Numbers by themselves look great on paper, but when you're able to see what does (or in most cases, doesn't) lie under the curve, the shiny marketing doublespeak quickly rubs off to reveal a rather tarnished finished product in reality.
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Peter Morris

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Re: Rcf 8006 and 9006
« Reply #45 on: October 03, 2018, 08:48:37 pm »

OORRRRR  I fyou use the "1 watt" method-how DO you apply 1 watt to the loudspeaker at all freq?  You don't, you apply A VOLTAGE, and the power is calculated-based on some impedance.

So if you use the 1 watt method and use the impedance peak around 41Hz as your "standard", you get to add 4.77dB to the sensitivity.

That is EXACTLY why Danley uses 2.83V for ALL models.   No matter the impedance

It keeps the drive level the same

Well, itís a nominal rating so what everyone else does is use 2 volts RMS for 4 ohm speakers and 2.83 for 8 ohms ... your box has a nominal impedance of 4 ohms.  By doing that it gives us a better way to compare different manufactures products and not mislead people who have not read or misunderstood the fine print regarding sensitivity specification .... I have had many people do this with your boxes when they compare them with others.
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Art Welter

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Re: Rcf 8006 and 9006
« Reply #46 on: October 04, 2018, 01:52:32 am »

Well, itís a nominal rating so what everyone else does is use 2 volts RMS for 4 ohm speakers and 2.83 for 8 ohms ... your box has a nominal impedance of 4 ohms.  By doing that it gives us a better way to compare different manufactures products and not mislead people who have not read or misunderstood the fine print regarding sensitivity specification .... I have had many people do this with your boxes when they compare them with others.
Peter,

Right, not everybody got the memo 9-10 years ago when Ivan was explaining to all of us why DSL decided to not bother adjusting voltage to the nominal impedance...
The discussions went on for pages and weeks, with specs like the ones on the 4 ohm TH-115 going through revisions to help support the decision for DSL to "choose to have a higher rated sensitivity" than what the nominal voltage used would suggest.

Art
« Last Edit: October 04, 2018, 01:56:05 am by Art Welter »
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John Schalk

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Re: Rcf 8006 and 9006
« Reply #47 on: October 08, 2018, 12:54:57 pm »

They do publish charts. Being powered cabs these of course are post processing. They also would appear to have the lowpass at the 50Hz setting.

https://www.rcf.it/c/document_library/get_file?uuid=ccc1d690-e611-4484-920d-45bbd2aa5660&groupId=20195

https://www.rcf.it/c/document_library/get_file?uuid=96242f83-a0e2-47ec-a970-f70f5bbf33c8&groupId=20195

Thanks Mike.  I am not sure how I missed those before.  Unfortunately, after comparing the two graphs side by side, it's clear that RCF used two very different system settings when they measured each sub.  I'm guessing that the 8006's response is with the Punch button engaged ("This switch provides a DEEP equalization (flat response down to 30 Hz) or a PUNCH equalization with a boosted equalization at 70 Hz.") and the low pass set to 80 Hz.  The 9006 appears to be measured from 30 Hz to 50 Hz without any similar tonal Eq.  Also, both graphs indicate -20dBu/1M but the output of the 8006 is roughly 6 dB higher at 50 Hz from that of the 9006.

What can we conclude from comparing the two graphs?  I guess it's clear that the 9006 is capable of a -3 dB response at 30 Hz relative to 50 Hz.  And we can see what the output of the 8006 looks like in Punch mode if my assumption is correct.  I don't think we can conclude that the 8006 is 6 dB louder than the 9006 though.  Since both of these subs are out of my price range, this is mostly academic to me anyway :) 
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