AudioKinesis Cabs Part VI...

[Mystic Michael]

Realize that he's still using the the 4 ohm driver, not the 8 ohm one. The 4/8 ohm switch just toggles off/on a network of resistors that bring up the impedance, with a bit of a drop in efficiency (and slight tonal changes). So, the Thiele/Small of the 4-ohm driver will always be the ones to consider for this specific case.

If you have it in 4 ohm "mode" (for lack of a better term), then adding a 2nd 4 ohm cab of whatever will make your head have a 2 ohm load attached (assuming cabs are in parallel, which they almost always are). If you have the switch in the 8 ohm position, and add a 2nd 8 ohm cab, it'll be a total 4 ohm load (again, assuming parallel).

Yes, I get all that. Just didn't know that it was all that straightforward to change impedance in this manner. Kewl.

Since the 4-ohm 3012 LF is already very inefficient @ 92.9 dB SPL, in 8-ohm mode it must be really inefficient. Good thing power is cheap.

Thanks,

MM

 

[Selta]

It is and it isn't. From the EE side of things it's a good bit more in-depth than what I explained... from the purely "make sound, go loud" live sound side of things though, yeah.

 

[DukeLeJeune]

Does this mean that the specifications of the 4-ohm 3012 LF (i.e. 550 watts RMS power rating, 92.9 dB SPL sensitivity, etc.) will apply, instead of the specs of the 8-ohm 3012 LF (i.e. 450 watts RMS power rating, 95.5 dB SPL sensitivity, etc.), even when the cab is being operated in 8-ohm mode? Does it mean that the cab can be operated just like any standard 4-ohm cab or standard 8-ohm cab...as long as it's set for the appropriate impedance level?

I think Eminence's spec of 92.9 dB efficiency is too low. My math says that the 4-ohm 3012LF is very slightly more efficient than the 8-ohm version. When the "8 ohm" switch is engaged (which adds series resistance to the 4-ohm woofer), the cab's efficiency drops to slightly below that of the stock 8-ohm woofer.

Eminence may have made a change to the 4-ohm 3012LF early on and didn't update all of the specs, because I can't find anything in the math or in my measurements that supports the 92.9 dB figure.

Given that the 4-ohm version is rated at 550 watts, technically the cab's power handling goes up to about 700 watts when we flip the switch and add the series resistance, but 150 of those watts are just going into heating up the resistors. So if you have a big enough amp, the cab can play just as loud in 8 ohm mode as it could in 4 ohm mode. But I'm not planning on making a big marketing pitch based on higher power handling because we're putting 27% of our wattage into heating up resistors. (For the record, the power handling of the series resistance is over 350 watts, and so there's plenty of safety margin beyond the 150 watts that the math calls for).

To answer your second question, the cab can be treated as a 4 ohm cab when in 4 ohm mode, and as an 8 ohm cab when in 8 ohm mode.

So guys, I'm in brainstorming here.... In conjunction w/ the new TC112 I posted above, I also have a two Hathor 1203 stack being constructed as well. My problem is that I'm friggin' loving the fullness and hifi quality of the TC112, and I'm finding that the mid switch on in "full nasty" mode provides an ample enough boost in the upper mid region to seem to be able to cut through a mix....

There is a piece of information that I've been holding back, and I think it will explain why punchdrunk is getting "ample enough boost in the upper mid region" when others have not.

The TC112v3 uses a different crossover topology which makes a difference in that region.

The 8-ohm 3012LF needs two smoothing filters to get to "smooth" mode. But the factory 4-ohm version only needs one, so I have a little bit more leeway to use crossover components for something else. The space available for crossover components is limited, and woofer filters eat up the most space and weigh the most not only because of the higher component values required but also because of the power handling called for. So anyway with the 4-ohm woofer, I'm able to use a crossover topology that lets me get a little more grindy out of the woofer's top end. That's what punchdrunk is hearing. Unfortunately I can't really retrofit this filter topology to earlier versions of the Thunderchild 112, as its success in this application is dependent on the specific characteristics of that new woofer.

 

[DukeLeJeune]

Realize that he's still using the the 4 ohm driver, not the 8 ohm one. The 4/8 ohm switch just toggles off/on a network of resistors that bring up the impedance, with a bit of a drop in efficiency (and slight tonal changes). So, the Thiele/Small of the 4-ohm driver will always be the ones to consider for this specific case.

Technically that's true, but in practice we can add the series resistance to the woofer's voice coil resistance and calculate what the effective or apparent change is to our T/S parameters.

Adding series resistance does modify the effective Re and Qes of the woofer. Re goes up by whatever the value of the series resistance is, and Qes goes up by a factor of (new Re)/(old Re). So if we add 1 ohm of series resistance to a 4 ohm woofer that has a Qes of .30, the new Re is 5 ohms, and the new Qes is (5/4) x .30 = .375. These changes also predict what happens to the system's efficiency and voltage sensitivity.

 

[Selta]

Technically that's true, but in practice we can add the series resistance to the woofer's voice coil resistance and calculate what the effective or apparent change is to our T/S parameters.

Adding series resistance does modify the effective Re and Qes of the woofer. Re goes up by whatever the value of the series resistance is, and Qes goes up by a factor of (new Re)/(old Re). So if we add 1 ohm of series resistance to a 4 ohm woofer that has a Qes of .30, the new Re is 5 ohms, and the new Qes is (5/4) x .30 = .375. These changes also predict what happens to the system's efficiency and voltage sensitivity.

Ah, wonderful! I made a bad assumption of how the resistance was being added. That is very, very cool. Sorry for misspeaking!

 

[DukeLeJeune]

Ah, wonderful! I made a bad assumption of how the resistance was being added. That is very, very cool. Sorry for misspeaking!

No problem, it's not obvious at all, and indeed technically the driver's parameters didn't change... we just added a resistor in series.

In the case of the 4-ohm Kappalite 3012LF in the Thunderchild 112v3, the switch raises the electrical Q from .32 to .41. That will still work for a vented box, but we may find that a slightly lower tuning frequency works better, and providing such is one of the reasons why I went from two 3" ports to four 2" ports. In sealed box mode, engaging the switch moves the -3 dB point from 93 Hz down to 74 Hz, which might be a useful.

 

[alaskaleftybass]

So, had an... interesting experience with my Thunderchild 118 tonight. I figured I'd come along and post it here, especially since some people were asking about that specific model earlier.

For all of my gigs, we have substantial PA support. In fact, for one of my bands, we don't even have amps on stage at all - it's all IEMs and FOH (some side fills for people not using IEMs). So, I've never really had a chance to let the TC118 loose and see what it can really do. It has gone loud before in rehearsal, but even with those occasions, I felt it's never been driven at all hard. Which, by itself is saying a lot as one of my bands has pretty bad self-control for volume at rehearsal (loud 6 piece metal band).

Anyway, this evening my newest project was rehearing for our debut gig next weekend. The studio we rehearse at has a 1700 sq. ft. "live room" with a 15'x23' stage, where bands put on shows and what not. That is a fair sized room, and it does have a hefty PA. Our band decided we wanted to use this room for rehearsal tonight because... why not?

At first, my instinct was to use the TC118 for stage monitoring, and let the PA do the heavy lifting. Then, I thought to myself "Hey, we're just kind of screwing around a bit... let's see what the TC118 can do afterall". I knew I'd find it's limit there. Drop-A tuned heavy metal with prog elements in a 1700 sq. ft. room, with a single 18" driver with about 600W behind it. It's going to end up fart city and I'll go through the PA... but only after I find out where this thing comes up short.

Sadly, that limit was not found tonight.

We did a rough sound check. Soundboard is about 2/3 of the way back in this room. At first, I was pretty hot back there apparently, as I got asked to turn down. I thought the guy was joking... but he wasn't. So I turned down to his liking, and then took a walk through a bit of the room. Pretty ballsy tone throughout the whole room.

We ran our set once, took a very brief break and came back to play it again. For giggles, I had everyone turn up a non-trivial amount. Yes, this is it, I'll finally, finally hear some farting and know where this thing peaks!

But... nope. Still no dice. This cab is a friggin' stud. I had the output clipping on my QSC, so I had to turn it down a smidge. The TC118 took the rated 600W and kept chugging - not the faintest hint of farting or stress. People at the soundboard were telling me their insides were shaking. I believe them, because everything on the stage was shaking fiercely. We all decided, collectively, that things overall were just painfully loud, and turned down again. Even at this absurd SPL, the tone was exactly the same as it was at home practice volume. Granted, in part, that's due to the modeler (Axe-Fx II) that I use, which keeps things consistent from the amp/fx side of things, but what the TC118 sounds like / reproduces is very similar at high SPL as it is at low.

So, sadly, if I ever really want to find the top of this thing, I'd need to buy a bigger power amp. I'd also need to find somewhere to use it. I think Duke rates the TC118 at 600W (IIRC), but, after tonight I have to say that must be conservative, or my amp is rated a bit high. Either way, even though I haven't found the top SPL limit of this, it's comforting to know that I can carry a lot of rooms with it if for some odd reason I need to.

I understand your awe and pride in the TC118. Heck, I don't own one and I'm in awe.

I'm more of the "aggressive midrange" kind of guy, i.e. the old overdriven SVT's of the 70's and 80's, Peavey Mark IV's, cranked 215's in big rooms, etc.

That leads me to my question. I'm wondering -- why is the H1855 seven pounds lighter than the TC118 even though the TC118 is more complex, larger, and more "hi-fi?"

Also, am I right to assume that the H1855 will be cloer to that old "classic rock tone?"

I'm thinking one day my dream will be to own a H1855, it may not be possible but would be nice if it was lighter than the TC118. Still, for the power that you're mentioning you are getting, @Selta , I'm so impressed with Duke's designs. I'm not sure what I will pair it up with if I ever buy the H1855, but I'm thinking either the Peavey MiniMega 1,000 watt mini head or the GK MB800....

Thanks

~Will

 

[Mystic Michael]

Also, am I right to assume that the H1855 will be cloer to that old "classic rock tone?"

I'm thinking one day my dream will be to own a H1855, it may not be possible but would be nice if it was lighter than the TC118. Still, for the power that you're mentioning you are getting, @Selta , I'm so impressed with Duke's designs. I'm not sure what I will pair it up with if I ever buy the H1855, but I'm thinking either the Peavey MiniMega 1,000 watt mini head or the GK MB800....

I'm not Selta. And I'm certainly not Duke (though I play one on TV). But FWIW, I think that the Hathor 1855 probably will get you quite close to "that old classic rock tone"...if your idea of classic rock tone is a 6.5 magnitude earthquake.

As for the ideal amp head to use, get the 1855 in the 4-ohm configuration, and match it up with a Carvin B1500 (1250 watts @ 4 ohms). That should rock the house. And the block. And the neighborhood. And the city...

MM

 

[punchdrunk]

Guys, I've elected to forego the two H1203 build, and go with the new (and improved ) two TC 112 V3 build. Just checks every box for me. Thanks for everyone's insightful/thoughtful input.

 

[Selta]

I understand your awe and pride in the TC118. Heck, I don't own one and I'm in awe.

I'm more of the "aggressive midrange" kind of guy, i.e. the old overdriven SVT's of the 70's and 80's, Peavey Mark IV's, cranked 215's in big rooms, etc.

That leads me to my question. I'm wondering -- why is the H1855 seven pounds lighter than the TC118 even though the TC118 is more complex, larger, and more "hi-fi?"

Also, am I right to assume that the H1855 will be cloer to that old "classic rock tone?"

I'm thinking one day my dream will be to own a H1855, it may not be possible but would be nice if it was lighter than the TC118. Still, for the power that you're mentioning you are getting, @Selta , I'm so impressed with Duke's designs. I'm not sure what I will pair it up with if I ever buy the H1855, but I'm thinking either the Peavey MiniMega 1,000 watt mini head or the GK MB800....

Thanks

~Will

I'm not capable of answering the TC versus Hathor questions at all, as I've only heard one Hathor once, and never owned one. For what it's worth, my tone is pretty midrange-y as well. Here's a somewhat recent recorded sample of an upcoming song from one of my bands:


The TC does mid grind very well, though I do really want to try an H1855 as well just to A/B the two. I just need someone local to buy one first

 

[punchdrunk]

Hell yeah, Selta!

 

[alaskaleftybass]

I'm not capable of answering the TC versus Hathor questions at all, as I've only heard one Hathor once, and never owned one. For what it's worth, my tone is pretty midrange-y as well. Here's a somewhat recent recorded sample of an upcoming song from one of my bands:


The TC does mid grind very well, though I do really want to try an H1855 as well just to A/B the two. I just need someone local to buy one first

Excellent! Thank you for sharing and good luck on your release! You sound excellent! I love that genre.

 

[DukeLeJeune]

...why is the H1855 seven pounds lighter than the TC118 even though the TC118 is more complex, larger, and more "hi-fi?"

Actually the Hathor 1855 is seven pounds heavier (50 pounds vs 43 pounds), maybe that's what you meant to say. Anyway the Hathor 1855 has about 20 pounds of drivers (uberwoofer + two mids) and the Thunderchild 118 has about 12 pounds of drivers (woofer + compression driver), so that's where most of the difference comes from.

 

[alaskaleftybass]

So which cab is recommended for the classic rock sound, or, if I got the TC118 which is lighter, could I use the switches to emulate that classic tone?

 

[DukeLeJeune]

So which cab is recommended for the classic rock sound, or, if I got the TC118 which is lighter, could I use the switches to emulate that classic tone?

Of the two, the Hathor 1855 is more the classic rock cab. The Thunderchild 118 will take EQ well, but it doesn't have a switch setting that emphasizes the upper-mid region.

The Hathor 1505 is lighter than the Thunderchild 118 and the math says it should get just as loud (its lower power handling is offset by its higher efficiency), and maybe even a little bit louder, if we factor in that upper-mid peak. While the woofer in the Hathor 1505 will fartout sooner, you can plug one of the ports and that will improve its fartout resistance.

 

[punchdrunk]

Hi guys, here's a quick, and less than ideal demo of the Mid Switch on the TC112v3... (Headphones are recommended)
Hopefully you can get the gist of it. The upper mid enhancement actually becomes more striking/apparent the further away from the cab you get. Also, two of the four ports are sealed in this demo.

 

[tombowlus]

I have a question for all the people out there who have a Hathor 1855 & a BEAD(G) tuned bass.
How is the low end & over all balance with all the ports plugged?

What would be really great would be if you could try it on a gig where you're familiar with the acoustics of the place: for at least one set with ports plugged & at least one set with ports not plugged.

[Tom Bowlus, I know you're a very busy man (especially now), but maybe one of these days you could check this out with a really tight-sounding amp.]

I should be able to do that. Remind me if I don't get back on this in a reasonable time period.

 

[tombowlus]

Hey guys, I see soo much love here for the 12's Hathors and TC's. I just realized: Duke has built a couple monsters: the TC 118 and Hathor 1855. They are pretty lightweight for their power handling and size.

Does anyone here have experience with either? Anyone using one of them for their main ROCK gig? I can't even comprehend what kind of output they would have! Woot woot ground shaking I hope....

I have a TC112AF, TC115AF (wide format), two 1203's and an 1855. The TC115AF actually does super on my rock gigs, and I can only imagine that a TC118 would be more of the same. The 1855 is indeed a monster, and it has this amazing mix of tightness, depth, speed and fullness to the lows which has to be heard to understood. The mids have a couple of different profiles, and are designed to cut through a mix. It's a fantastic rock cab!

 

[TomB]

I have a TC112AF, TC115AF (wide format), two 1203's and an 1855. The TC115AF actually does super on my rock gigs, and I can only imagine that a TC118 would be more of the same. The 1855 is indeed a monster, and it has this amazing mix of tightness, depth, speed and fullness to the lows which has to be heard to understood. The mids have a couple of different profiles, and are designed to cut through a mix. It's a fantastic rock cab!

I too use a TC115AF (wide format) not just for rock but for most gigs. I haven't even come close to maxing out what that driver can do, at any volume that I have thrown it. I too can only imagine that the 18" version would provide more of the same goodness. The TC115 is light, even with the AF feature, so I would guess the 118 would be in the same weight ball park (absent the rear tweeter of the AF). Duke can confirm or deny. I think the mid-switches would be fun to have, but I haven't moved mine from the "full-on" position. It's a real "Swiss Army Knife" cab IME. I'd love to try out a Hathor some day for comparison, and will stay tuned here for comments.

 

[shrigg]

Here are a few examples of how a TC115 Wide + TH500 sounds in the mix. These show a decent variety of fingerstyle and slap and were recorded with an iphone 4 as I recall