Big E speakers: Pt 2

[lelandcrooks]

88 db, doubled once to two drivers is 91db, doubled twice to four drivers is 94 db, doubled three times to 8 drivers is 97db.

Isn't this only true if it's entirely a parallel connection? An 8 driver cab to maintain 4 ohms has to have a series/parallel. Each series connection nets 0 gain, only more vd capacity.

 

[Mike Arnopol]

And while the multiple drivers can indeed account for some increase in output as opposed to the simple combination of vd of the drivers---not nearly to the degree experienced.

With the Rach E sub (a single Kappalite 12) Leland has made real world comparisons to speakers with 3 times the dynamic capabilities of the single 12. So in that case there is no multiple-driver interaction at play.

In comparing the 45 I get the same increases in dynamic range when compared to the combined Vd of the 4 drivers (160) when compared to the Crazy 88 (320). The 88 craps out way before the 45. So while increasing the amount of drivers yields a slightly disproportionate increase as compared to a simple combination of drivers Vd's it can't account for the dramatic increase experienced. While the combination of drivers does increase efficiency even with series/parallel combinations---the increase in dynamic capabilities is about the same with the 45 and 85. The 88's are a known entity. Two 88's crap out at about the same time when compared to the 85.

Maybe Duke can chime in but he's told me that there is an increase in dynamic capability when combining drivers---but not nearly to the degree experienced here, And RP did note that when he tried the 28 at lower volumes the volume of the 28 was lower in comparison with other speakers and then jumped up a disproportionate amount as more power was applied.

One more thing---Faital is--let's say--a bit optimistic in their measurements. Duke measured the 8PR200 which claims efficiency of 95 db. He said it was more like 92db. Eminence is a bit more--shall we say--realistic. Also, the comparisons of Vd is a bit more dramatic when you take in consideration that Faital and Eminence use different formulas to calculate Xmax. Duke said that the claimed Xmax of 8.15 on the 8PR would be more like 6mm when compared apples to apples with the Eminence.

 

[Mike Arnopol]

88 db, doubled once to two drivers is 91db, doubled twice to four drivers is 94 db, doubled three times to 8 drivers is 97db.

The calculated sensitivity of a 3015LF is 96-97db--I believe Duke's kappalite variant is 97.

So your gain from the waveguide seems to be about zero db (depending on those 3 notches - not sure what that winds up meaning for the chart).

Also, look at that burp in the upper bass -- I am pretty sure you can thank the way the tuning wanders with power and drives the tuning frequency up, exaggerating the upper bass for that.



Side note on the low end: You're going to need to figure out a way to model the low end, since that's how everyone else does it who doesn't measure the lows. Either that or measure the lows.

Edit, to add: What I would recommend is you build a straw man traditional ported box to compare to any of the vortex cabs. Make a vertical 4x5 with the 5Fe20's and measure it against an MA45. That'd give you more of an idea of what the vortex really adds.

Gee Ryan---I'm trying to not be a little put off by your tone.

Well I guess I'll take the high road.

I did do half space measurements outside. Just the speaker laying on it's back which obviously introduces artifacts but I also did measurements of the Thunderchild and Fearful cabs since those are based on modeling. So while not entirely scientific it does give me comparisons with known entities. The Thunderchild did measure approximately -3db at about 57hz if I remember correctly---which is consistent with Duke's modeling. There were a few dips and humps above that that Duke said were the artifacts of the speaker not being buried so the ground plane is the same as the baffle. So--a psuedo half space. I can't remember what the Fearfuls measured but I do remember it was consistent with the modeling that Dave had done. I did it at different distances and different power levels to see comparisons. I tested Big E 28's 46's 45's and a 210 with 3010lf's. My -3db points were all pretty close to about 5 to 10 hz lower than the published Fs's.

While obviously a flawed method at least I was able to compare to known entities within the same parameters where we trust the varacity of the modeling.

 

[Arjank]

Edit, to add: What I would recommend is you build a straw man traditional ported box to compare to any of the vortex cabs. Make a vertical 4x5 with the 5Fe20's and measure it against an MA45. That'd give you more of an idea of what the vortex really adds.

To make it even more simple, just close these vortexes so you get a closed box and measure again. Then compare and post'm here

 

[Mike Arnopol]

I'll do it!--as soon as I'm caught up with orders!

 

[tombowlus]

The Thunderchild did measure approximately -3db at about 57hz if I remember correctly---which is consistent with Duke's modeling.

FWIW, that jives pretty closely with my measurements of the TC112AF, as well.

 

[3rdcurve]

Mike, did you gets -3db point for the 5" cabs? Also, my genz head has a pretty nice filter built in, would I still need an Fdeck?

 

[christw]

Mike, did you gets -3db point for the 5" cabs? Also, my genz head has a pretty nice filter built in, would I still need an Fdeck?

If it's a Shuttle, I believe it's already got a filter somewhere in the 60-80 Hz range.

 

[rpsands]

Gee Ryan---I'm trying to not be a little put off by your tone.

Well I guess I'll take the high road.

I did do half space measurements outside. Just the speaker laying on it's back which obviously introduces artifacts but I also did measurements of the Thunderchild and Fearful cabs since those are based on modeling. So while not entirely scientific it does give me comparisons with known entities. The Thunderchild did measure approximately -3db at about 57hz if I remember correctly---which is consistent with Duke's modeling. There were a few dips and humps above that that Duke said were the artifacts of the speaker not being buried so the ground plane is the same as the baffle. So--a psuedo half space. I can't remember what the Fearfuls measured but I do remember it was consistent with the modeling that Dave had done. I did it at different distances and different power levels to see comparisons. I tested Big E 28's 46's 45's and a 210 with 3010lf's. My -3db points were all pretty close to about 5 to 10 hz lower than the published Fs's.

While obviously a flawed method at least I was able to compare to known entities within the same parameters where we trust the varacity of the modeling.

It's a good start, Mike! I'm Not negative at all, I'm just skeptical.

I've heard claims of more than 3db of gain and low end performance that I think are impossible - I want to be sure your methodology rules the statements in or out, that is all.

* Also, re: the low end - I wasn't poking at your methodology, just saying that because the Vortex is claimed to impart unique characteristics, modeling it is likely to be a challenge - so you're pretty much stuck measuring it, and should aim toward getting a good low end measurement protocol that would be accepted by the same guys who accept TS modeling of ported enclosures.

** And more, if it's accurate, having serious sound at 55hz out of a woofer with an FS of 65hz is pretty impressive

 

[rpsands]

Isn't this only true if it's entirely a parallel connection? An 8 driver cab to maintain 4 ohms has to have a series/parallel. Each series connection nets 0 gain, only more vd capacity.

I am welcome to be shown to be wrong, but I believe the series wiring just changes the impedance, which changes how much power gets through - not how sensitive the system is per watt that actually gets through.

If you used 8x 91db 8 ohm woofers to get a 4 ohm 8x10, would it be less sensitive than 8 x 91db 32 ohm woofers in parallel? (All other things being equal)

I don't believe so.

 

[rpsands]

I talked to the MVW guys on FB and they said that this test was at 1w! That would explain the lack of vortex enhancing the sensitivity at least as described.

 

[3rdcurve]

If it's a Shuttle, I believe it's already got a filter somewhere in the 60-80 Hz range.

It's a Streamliner 900

 

[Mike Arnopol]

I think the best I can do is true half space measuring outside. Unfortunately my wife won't let me dig up the back yard. You have to have the baffle at the same plane as the ground for the best half space measurements.So I'm thinking of getting a decent power inverter .And driving to a place that's quiet where I can dig the proper hole. Then turn the car off and use the inverter just running off of the car battery for the few seconds that the signal would be applied.

Does this sound maniacally stupid---guys like Arjank and Tom? I know that the only true way of doing a full space measurement is literally having it suspended way off the ground and measuring. Maybe the fire department can help out.

 

[rpsands]

I am not sure what good 1w measuring is going to do for you man - it doesn't really tell the whole story.

And just dig up the back yard then plant something there afterwards

 

[Mike Arnopol]

I'm talking about measuring at power

 

[Vince Klortho]

I am welcome to be shown to be wrong, but I believe the series wiring just changes the impedance, which changes how much power gets through - not how sensitive the system is per watt that actually gets through.

If you used 8x 91db 8 ohm woofers to get a 4 ohm 8x10, would it be less sensitive than 8 x 91db 32 ohm woofers in parallel? (All other things being equal)

I don't believe so.

A series circuit splits the voltage and current is the same. A parallel circuit splits the current and voltage is the same. Four drivers in a series/parallel configuration will each get half the voltage, half the current, and one quarter of the power. If you combined two four-driver S/P configurations then the current would split again and each would have an eighth of the power. Sensitivity should be same as eight drivers in parallel.

The difference would be with eight in parallel each gets the same voltage and one eighth of the current while with eight in two S/P configurations each gets half of the voltage and one quarter of the current. It is current that causes heat so eight in parallel would be less demanding on the drivers.

 

[Downunderwonder]

Someone was saying on the measuring project thread, you can measure with mic flat on the ground and combine with measure with cab laying on it's back with mic up high ladder to take the baffle step hole in the ground shenanigans out of the picture.

 

[Foz]

Someone was saying on the measuring project thread, you can measure with mic flat on the ground and combine with measure with cab laying on it's back with mic up high ladder to take the baffle step hole in the ground shenanigans out of the picture.

No need - just use Gander's ground plane method.

Invalid Link Removed

 

[tombowlus]

I think the best I can do is true half space measuring outside. Unfortunately my wife won't let me dig up the back yard. You have to have the baffle at the same plane as the ground for the best half space measurements.So I'm thinking of getting a decent power inverter .And driving to a place that's quiet where I can dig the proper hole. Then turn the car off and use the inverter just running off of the car battery for the few seconds that the signal would be applied.

Does this sound maniacally stupid---guys like Arjank and Tom? I know that the only true way of doing a full space measurement is literally having it suspended way off the ground and measuring. Maybe the fire department can help out.

FWIW, I would never run tests using an amp operating off of a power inverter being powered by a car battery (even with the engine running). Then again, I don't feel that taking measurements (of amps) using a highly regulated power supply is truly representative of what a player will see in the real world.

That being said, there are definitely some good reasons for choosing to set up for a true half space measurement, though there are some downsides, as well. Not the least of these are the physical setting requirements (which usually puts you outside). Then, there's the background noise often associated with outside measurements.

Ground plane measurements are probably going to be your best bet, if you want to use a more simple measurement rig. Alternately, you can use a measurement system like Audiomatica's Clio, which measures the delay associated with reflected signals coming back to the mic and can use a stepped, gated frequency sweep which measures the direct signal, but cuts off the reflected signal.

Of course, if you also want to take off-axis measurements, then that opens up several additional factors to be considered.

But for what you are doing, I'm guessing that the ground plane measurement approach would be the easiest way to get good results without modelling.

 

[mntngrown]

And so if I just said "keep them orders comin out of the factory man! and the players will "keep on keepin on!"
I really don't understand why Mike et al have to provide this "I am going to bury a dead carcass in a hole at midnight on a full moon in the savanna and put the unboxed speakers on top to prove what we are talkin about.
If bass players are buying the cabs, and for the most part are really digging what they are getting, I personally think the give me proof under my rules of measurement dudes are really just an annoyance, but no doubt part of the process. I am really surprised from the response from my fellow fEarful builders too. No one had to prove anything to me when I went fEarful. It was obvious to me that a new game changer driver 3015lf was being maximized in an enclosure, by a brilliant designer who coupled that driver with the best mid range speakers and maximized a crossover between them. But somehow this new concept has been subjected to the harshest skepticism by some of the very people who were at the forefront of the fEarful adoption. I really believe if a couple of those guys could play their signal chain through my BigE 4x8 with the proprietary 8's they would simply say OK, I get it.
Now I will point out that I am in no hurry to sell my self built fEARful 1515/66 as I love that cab. But my Arnopol BigE48 is a much smaller packer and can handle most any gig I do and really does have that amazing dispersion thing! I love both cabs. YMMV