AudioKinesis Cabs Part VI...

[DukeLeJeune]

I'm not sure how big a deal it is in practice, but when I only open two ports I do one high and one low to perhaps help with thermal flow and I figure it may better balance the load on the woofer cone.

YUP!!

If you have the two (out of four) ports that are open on a diagonal, instead of one above the other, that maximizes the airload symmetry on the back of the cone while preserving a bit of "chimney effect" cooling. This is what the designer of the Kappalite woofers, Jerry McNutt of Eminence, suggested to me many years ago.

 

[DukeLeJeune]

With the 8 ohm cabs, I'll never, ever be able to run singly, or paired, the Hathor to it's full 500 watt design capabilities and goodness with my 800 watt amp.

This thought occurs to me:

An amp that does 800 watts into 4 ohms probably does more than 400 watts into 8 ohms. I can't recall encountering an amplifier that really doubles its wattage as the impedance of the load is halved.

Over in the high-end home audio world, many years ago a company named Krell made waves by building an ultra-beefy solid state amplifier whose 8-ohm rated output power doubled into 4 ohms and doubled again into 2 ohms. This was a first. Nobody else made an amp that could do this. Krell immediately stood out from the crowd and soon attained legendary status. Krell became the amplifier of choice for driving loudspeakers with nasty impedance curves.

Well eventually the Krell amps were measured by a high-end audio magazine in the course of a review. Turns out their 2 ohm output claim was right on the money, but the amp actually put out MORE than its claimed output into 4 ohm and into 8 ohms! So the Krell amp's behavior in this regard was nothing special - the manufacturer simply chose to under-state the power into 8 ohms and 4 ohms to make it appear like their amp had this ultra-beefy power supply and ultra-linear output transistors. It was still a very capable amp of course.

I may be wrong and I'm NOT an amplifier technician, maybe your amp's output into 8 ohms really is one-half of its output into 4 ohms, but if I had to guess, I'd guess that its actual output into 8 ohms is more than half of its output into 4 ohms.

 

[TomB]

I don't know how relevant this is, given that what I have is a Birdhaus cab, but my cab's four Faital 8PR200 (total 800 watts power handling) speakers sound pretty great to me driven by a mere 210 watts. I think I'm using pretty much all of the 210 watts, since I get pretty hard into the power amp's DDT circuitry (DDT "compression" LED lights up on most of the low notes) unless I'm playing softly. In a few song sections I really dig in to get some "gnar," though, because I am playing rock stuff that goes well with dirty P-bass.

Anyway, in this setting my decades-old underpowered 3-rackspace Peavey amp still vibrates stuff off of the basement shelf If I'm not careful, I like the sound of the DDT kicking in and lending a touch of extra compressed feel when driven hard, and even though the speakers should be loafing in this scenario, it seems to sound full and lively. I would think 400 watts into a 500-watt rated cab ought to sound pretty big and the slight mismatch wouldn't be something to worry about...?

(But someday I'd like to try a 500+ watt amp through my cab, I'll admit...)

“Gnar” - Heh, that’s a good one

 

[nutdog]

If you're at a gig wishing you needed an extra 100 watts to max a 112 you'd be better served by adding a second 112. IMO, IMHO, YMMV, FWIW, WWJD, XYZ...

 

[wave rider]

If you're at a gig wishing you needed an extra 100 watts to max a 112 you'd be better served by adding a second 112. IMO, IMHO, YMMV, FWIW, WWJD, XYZ...

^^^^ FTW! ^^^^

 

[stubborne]

Duke, given your Hathor 1203 design specs, what wattage would you recommend to take full advantage of your intended design capabilities?

@DukeLeJeune same question for the H1506. Not sure I ever asked you what the max rated wattage is for that cabinet.

 

[DukeLeJeune]

@DukeLeJeune same question for the H1506. Not sure I ever asked you what the max rated wattage is for that cabinet.

Five hundred watts, into 4 ohms. The 1506 uses a custom woofer based on the Kappalite motor.

 

[fig]

I may be wrong and I'm NOT an amplifier technician, maybe your amp's output into 8 ohms really is one-half of its output into 4 ohms, but if I had to guess, I'd guess that its actual output into 8 ohms is more than half of its output into 4 ohms.

Yesterday, I asked the designer of the Mesa Subway amps, agedhorse, a question about power above Mesa's posted specs. He says there is more power available. Puts it closer to your stated specs, so cool.

This quote is taken from your posting around Xmas, 2015:

Eminence makes a 4-ohm version of the 3012LF. The efficiency is essentially the same, but the voltage sensitivity is 2 dB higher, which means that a "300 watts into 8 ohms, 500 watts into 4 ohms" amp will drive the cab to about 2 dB louder.

The 4-ohm 3012LF is rated at 550 watts (it may well handle more that that - that's where Eminence stopped testing)

Is that the one you said Eminence discontinued? What a little beast! Any idea why they stopped building it and relegated it to their custom build shop?

 

[DukeLeJeune]

Is that the one you said Eminence discontinued? What a little beast! Any idea why they stopped building it and relegated it to their custom build shop?

The 4-ohm Kappalite 3012LF was discontinued because Eminence wasn't selling enough of them.

The spec sheet on the 4 ohm version of the Kappalite 3012LF says that it's a 92.9 dB woofer, whereas the 8 ohm version's spec sheet says that it's a 95.5 dB woofer. The difference is 2.6 dB ("on paper"). And I think that "92.9 dB" number scared people away. I don't think anybody bothered to really dig into the reasons for the discrepancy in the specs.

Eminence measures their woofers' voltage senstivities based on the voltage that would be 1 watt into the nominal impedance. So the 8 ohm woofer gets 2.83 volts, and the 4 ohm woofer gets 2.0 volts. But the 8 ohm version is a "low 8 ohms" woofer, while the 4 ohm version is a "high 4 ohms" woofer, and arguably closer to being a "6 ohms" woofer. So following Eminence's testing protocol, the 4 ohm version gets short-changed by about 1.3 dB worth of voltage. (If they each got 1 watt based their minimum impedance, rather than their "nominal" impedance, the 4 ohm version would be .1 dB more efficient.)

The other 1.3 dB of the 2.6 dB total difference comes from the upper end of the response curves. Eminence uses the average SPL over the claimed bandwidth of the driver to calculate the efficiency. So if one driver has more upper-end bumpage than another, that boosts its calculated efficiency. Well, the 8 ohm version has considerably more upper-end bumpage than the 4 ohm version, so that's where the rest of its "on paper" advantage comes from. This makes the 8 ohm version arguably the better choice for the Hathor and Changeling cabs wherein we use that upper-end bumpage, but in turn the 4 ohm version is arguably the better choice for the Thunderchild cabinets wherein we equalize away that upper-end bumpage. The 8 ohm version still works fine for the Thunderchild cabs, it just takes more crossover parts to get there.

I wrote Eminence an e-mail explaining my theory for why the 3012LF-4 wasn't selling, and suggested they either "measure with a more optimistic yardstick" or start calling it a 6 ohm woofer (it would be a "low 6 ohms" woofer), which would have raised its sensitivity "on paper" from 92.9 dB to 94.7 dB. Well they obviously didn't choose to do either.

 

[maisbass]

I have a 4ohm Kappalite 3012LF. I replaced the 8ohm Kappa in my Hathor 1203 with the 4 ohm Kappa. The change didn't move me at all. I didn't really notice any difference in volume per se, but the 4 ohm seemed like it was a bit much speaker for the 1203. There seemed to be more vibrations/artifacts I was hearing from the cab that I didn't notice with the 8ohm. I actually think the 8ohm sounds better in the 1203 than the 4ohm. IMO...

I wound up putting the 8ohm back in.

 

[fig]

Thanks for posting your experience, maisbass.

Thank you, Duke, for taking the time to answer my question.

I'm curious, when you had the 4 ohm speakers available for the Hathors, were you selling more of those, or the 8 ohm versions? I'm thinking 8 ohm...

 

[DukeLeJeune]

Thanks for posting your experience, maisbass.

Thank you, Duke, for taking the time to answer my question.

I'm curious, when you had the 4 ohm speakers available for the Hathors, were you selling more of those, or the 8 ohm versions? I'm thinking 8 ohm...

I might have shipped 2 or 3 Hathor 1203's with the 4 ohm woofer. The rest were all 8 ohms.

 

[fig]

Ok, didn't expect that. That's quite a difference.

Thanks, again, for your time.

 

[mexicanyella]

I believe I am going to get to use the Birdhaus 48 at an outdoor gig in May. Our first gig as a band, playing an afternoon set amongst a bunch of other bands. I am excited. It will be my first gig as a bassist and my first gig since, like, 2003.

I don't know anything about the PA yet, or if there'll be backline provided. I think my 210-watt power amp and one Birdhaus, which works great in the basement, might be marginal in an outdoor setting. So this is premature, but...

...has anyone here ever run a multi-Birdhaus rig? Or paired a Birdhaus with some other cab? I realize I could be using a more powerful amp to drive the Birdhaus before worrying too much about additional cabs, but hey, this is blue-sky thinking, man.

Is the very act of asking about multi-Birdhaus cabs missing the actual point of the Birdhaus cab's design? Like, "Hey Mexicanyella, a more appropriate approach for a guy like you would be to set a dumpster on fire, then beat on it with a log."

I really like how the cab sounds, and was picturing a second one on top of it, possibly inverted, bringing the side woofers closer together for possibly more effective acoustic coupling. Not sure if I understand this phenomenon enough to even speculate about it.

All thoughts and suggestions welcome, even ones that recommend beating on flaming dumpsters instead of playing a bass.

 

[TomB]

I believe I am going to get to use the Birdhaus 48 at an outdoor gig in May. Our first gig as a band, playing an afternoon set amongst a bunch of other bands. I am excited. It will be my first gig as a bassist and my first gig since, like, 2003.

I don't know anything about the PA yet, or if there'll be backline provided. I think my 210-watt power amp and one Birdhaus, which works great in the basement, might be marginal in an outdoor setting. So this is premature, but...

...has anyone here ever run a multi-Birdhaus rig? Or paired a Birdhaus with some other cab? I realize I could be using a more powerful amp to drive the Birdhaus before worrying too much about additional cabs, but hey, this is blue-sky thinking, man.

Is the very act of asking about multi-Birdhaus cabs missing the actual point of the Birdhaus cab's design? Like, "Hey Mexicanyella, a more appropriate approach for a guy like you would be to set a dumpster on fire, then beat on it with a log."

I really like how the cab sounds, and was picturing a second one on top of it, possibly inverted, bringing the side woofers closer together for possibly more effective acoustic coupling. Not sure if I understand this phenomenon enough to even speculate about it.

All thoughts and suggestions welcome, even ones that recommend beating on flaming dumpsters instead of playing a bass.

I guess I’d try it out with a more powerful head and see what it can do. If it just won’t get loud enough then sure, more cab. But I’ve played a ton of loudish outdoor gigs with 500 watts and a single AK115. I’d at least check it out by itself.

 

[mexicanyella]

I guess I’d try it out with a more powerful head and see what it can do. If it just won’t get loud enough then sure, more cab. But I’ve played a ton of loudish outdoor gigs with 500 watts and a single AK115. I’d at least check it out by itself.

Thanks for the info; good to know. That seems like the next logical step up in power level.

 

[Pat C.]

That 48 can probably take a whole lot more power than you're currently capable of giving it. And with a high pass filter set in line at the appropriate frequency (I'd consult with Duke on that) it could probably do well with any of the 800-1000 watt heads out there.

Adding a second Birdhaus complicates some of the potential interference issues you get when you combine speakers, period. Since this cab is designed to shoot sound from 3 sides I'd bet it's even harder to predict the outcome. In general it should be louder, but then there's the questions of how will the side speakers interfere with each other, will frequencies that were previously in phase in one direction now get cancelled out, etc. You wouldn't want to inadvertently reduce the multi-directional goodness that is inherent in the design.

My first move would be an upgraded, high power amp with a HPF. That would maximize your current rig before even needed to consider a second cab.

I believe I am going to get to use the Birdhaus 48 at an outdoor gig in May. Our first gig as a band, playing an afternoon set amongst a bunch of other bands. I am excited. It will be my first gig as a bassist and my first gig since, like, 2003.

I don't know anything about the PA yet, or if there'll be backline provided. I think my 210-watt power amp and one Birdhaus, which works great in the basement, might be marginal in an outdoor setting. So this is premature, but...

...has anyone here ever run a multi-Birdhaus rig? Or paired a Birdhaus with some other cab? I realize I could be using a more powerful amp to drive the Birdhaus before worrying too much about additional cabs, but hey, this is blue-sky thinking, man.

Is the very act of asking about multi-Birdhaus cabs missing the actual point of the Birdhaus cab's design? Like, "Hey Mexicanyella, a more appropriate approach for a guy like you would be to set a dumpster on fire, then beat on it with a log."

I really like how the cab sounds, and was picturing a second one on top of it, possibly inverted, bringing the side woofers closer together for possibly more effective acoustic coupling. Not sure if I understand this phenomenon enough to even speculate about it.

All thoughts and suggestions welcome, even ones that recommend beating on flaming dumpsters instead of playing a bass.

 

[shwashwa]

id try stacking them on top of each other

 

[nutdog]

Do you have multiple birdhaueses (birdhausi?)? If so, hook’em up and give it whirl.

 

[mexicanyella]

My current bass cab inventory consists of one (1) Haus, Bird, 48.

The thinking that nudged me in the direction of contacting Duke in the first place was curiosity about a one-cab solution that could handle bass, guitar and lap steel. I was all fired up about reducing my gear footprint. The Haus, Bird, 48 does what I need it to, and well, and in a compact, easy-to-store-and-carry fashion. Last night I was all fired up about the prospect of playing a gig again. I may have posed my question a bit prematurely.