AudioKinesis Cabs Part VI...

[DukeLeJeune]

I wonder if I could get you guys' advice on something.

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. Which can be useful if you don't have a "500 watts into 8 ohms" amp.

I could install a switch that would bump up the cab's impedance to a minimal "8 ohm load", bringing its voltage sensitivity back down by said 2 dB in the process, and now it could be paralleled with another 8 ohm cab and safely be driven by an amp rated to drive a 4 ohm load.

The penalty would be about one pound in weight, for the circuitry needed to make the switch work safely at 500+ watts. I'm already doing this in the Hathor 1505 and the latest version of the Thunderchild 115, but in those big cabs the additional pound of weight is of less consequence than it would be in a TC112 or Hathor 1203 cab.

On possible benefit would be that in "8 ohm mode" the bottom end warms up a bit, so it's sort of like a tone switch for the lows (and if you don't want the extra lows, plug a port). The 4-ohm 3012LF is rated at 550 watts (it may well handle more that that - that's where Eminence stopped testing), and in "8 ohm mode" the cab is theoretically good to about 700 watts, though some of that wattage would just be going into heating up resistors. But you wouldn't actually lose any SPL headroom - it just would take you more watts to get there.

Of course I could offer the switch as an option, but I'd rather not have a whole bunch of different versions of the same cab (8 ohm version, 4 ohm version, 4/8 ohm version).

So let me know your thoughts.

Thanks!

Duke

 

[fast slapper]

Would it be too much hassle logistically to make it optional? While the versatility is nice it seems many customers of your cabs are packing some pretty serious heat as well and power gets cheaper all the time.

 

[DukeLeJeune]

Would it be too much hassle logistically to make it optional? While the versatility is nice it seems many customers of your cabs are packing some pretty serious heat as well and power gets cheaper all the time.

Thanks for replying, very good points. Yup, I can offer it as an option.

 

[tombowlus]

I think the option is a good idea. And for the folks whom would benefit from the option, I would think that the weight increase would be more than acceptable. How much would this option cost?

 

[Jeff Moote]

I wonder if I could get you guys' advice on something.

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. Which can be useful if you don't have a "500 watts into 8 ohms" amp.

I could install a switch that would bump up the cab's impedance to a minimal "8 ohm load", bringing its voltage sensitivity back down by said 2 dB in the process, and now it could be paralleled with another 8 ohm cab and safely be driven by an amp rated to drive a 4 ohm load.

The penalty would be about one pound in weight, for the circuitry needed to make the switch work safely at 500+ watts. I'm already doing this in the Hathor 1505 and the latest version of the Thunderchild 115, but in those big cabs the additional pound of weight is of less consequence than it would be in a TC112 or Hathor 1203 cab.

On possible benefit would be that in "8 ohm mode" the bottom end warms up a bit, so it's sort of like a tone switch for the lows (and if you don't want the extra lows, plug a port). The 4-ohm 3012LF is rated at 550 watts (it may well handle more that that - that's where Eminence stopped testing), and in "8 ohm mode" the cab is theoretically good to about 700 watts, though some of that wattage would just be going into heating up resistors. But you wouldn't actually lose any SPL headroom - it just would take you more watts to get there.

Of course I could offer the switch as an option, but I'd rather not have a whole bunch of different versions of the same cab (8 ohm version, 4 ohm version, 4/8 ohm version).

So let me know your thoughts.

Thanks!

Duke

I think it sounds like a great option. Would it bump up the base cost of the Hathor 1203 or TC112 (if it were to be offered as standard)? I can definitely think of situations where that would be a useful feature for me with the Hathor 1203 and lower powered amps.

On the other hand, it does pretty well as a small cab and getting something like the 1505 (with said switch) for bigger stuff, with the option to add a 1203, would cover just about anything.

Also you mention the 8 ohm mode would warm up/add to the low end. Does that mean in 4 ohm mode, it sounds the same as the current 8 ohm models without the option?

 

[Marial]

A difference of less then five pounds wouldn't be an issue for me and I'm hard pressed to to think a one pound difference would be a deal breaker for anyone. I think having it as an option is the way to go. One of the reasons I ditched my Demeter VTBP800D was because I ran into thermal shut down enough times that I no longer trusted the amp and I suspect it was because the TC212 is 4 ohms. That wasn't supposed to be an issue for the amp, but I think it was and the ability to go 8 ohm might have helped.

 

[Passinwind]

Please tolerate my ignorance in asking when 4ohm and 8ohm "switches" morphed from trickery, nonsense, and controversial quackery to an effective, real-world option? Or, is this controversy something from overactive, often-trouble-causing imagination?

There have always been right ways and wrong ways (or better and worse, at least) to make this idea work. Link Removed

 

[Guitarodeo]

So, assuming this is effective and viable, why not package this in an outboard interfacing device that could be used with applicable cabinets/situations?

For me personally, I am trying to reduce the items I gig with, not add to them. An integrated option with nominal weight gain and sound alteration would be most welcome.

 

[John D Harris]

I wonder if I could get you guys' advice on something.

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. Which can be useful if you don't have a "500 watts into 8 ohms" amp.

I could install a switch that would bump up the cab's impedance to a minimal "8 ohm load", bringing its voltage sensitivity back down by said 2 dB in the process, and now it could be paralleled with another 8 ohm cab and safely be driven by an amp rated to drive a 4 ohm load.

The penalty would be about one pound in weight, for the circuitry needed to make the switch work safely at 500+ watts. I'm already doing this in the Hathor 1505 and the latest version of the Thunderchild 115, but in those big cabs the additional pound of weight is of less consequence than it would be in a TC112 or Hathor 1203 cab.

On possible benefit would be that in "8 ohm mode" the bottom end warms up a bit, so it's sort of like a tone switch for the lows (and if you don't want the extra lows, plug a port). The 4-ohm 3012LF is rated at 550 watts (it may well handle more that that - that's where Eminence stopped testing), and in "8 ohm mode" the cab is theoretically good to about 700 watts, though some of that wattage would just be going into heating up resistors. But you wouldn't actually lose any SPL headroom - it just would take you more watts to get there.

Of course I could offer the switch as an option, but I'd rather not have a whole bunch of different versions of the same cab (8 ohm version, 4 ohm version, 4/8 ohm version).

So let me know your thoughts.

Thanks!

Duke

I guess I'm the contrarian, I don't think the SPL difference would be worth any extra expense & complexity.
On the other hand, I'd rather have 'more amp than I need' as opposed to 'just enough amp to do the job', so 8 ohm wouldn't be a problem anyway.
I do like that you're always thinking outside the box in trying to help us musicians & our obsessive gearitis.

 

[svtb15]

I think that it is a GREAT IDEA for an OPTION..
One pound is not a deal breaker at all.. . PRICE would be more of a consideration to many ..
But since it is an Option that would be up to them to decide if they need it or not. SO I think it would be a great option..

 

[DukeLeJeune]

I think the option is a good idea. And for the folks whom would benefit from the option, I would think that the weight increase would be more than acceptable. How much would this option cost?

Thank you Tom. Ballpark fifty bucks, it looks like.

I think it sounds like a great option. Would it bump up the base cost of the Hathor 1203 or TC112 (if it were to be offered as standard)? I can definitely think of situations where that would be a useful feature for me with the Hathor 1203 and lower powered amps.

On the other hand, it does pretty well as a small cab and getting something like the 1505 (with said switch) for bigger stuff, with the option to add a 1203, would cover just about anything.

Also you mention the 8 ohm mode would warm up/add to the low end. Does that mean in 4 ohm mode, it sounds the same as the current 8 ohm models without the option?

The base price would be bumped up, to cover the additional labor and materials cost. And yes, the math says that in 4 ohm mode, the sound should be just about like the 8-ohm version.

A difference of less then five pounds wouldn't be an issue for me and I'm hard pressed to to think a one pound difference would be a deal breaker for anyone. I think having it as an option is the way to go. One of the reasons I ditched my Demeter VTBP800D was because I ran into thermal shut down enough times that I no longer trusted the amp and I suspect it was because the TC212 is 4 ohms. That wasn't supposed to be an issue for the amp, but I think it was and the ability to go 8 ohm might have helped.

Thanks Marial. The switch that I'm describing wouldn't really be practical to implement on the TC212, unfortunately, at least not in my opinion. Imo the impedance needs to start out as a "high 4 ohms" load in order for the switch to be practical. I'll explain more in my next post, which will address staccotogrowl's questions.

I guess I'm the contrarian, I don't think the SPL difference would be worth any extra expense & complexity.
On the other hand, I'd rather have 'more amp than I need' as opposed to 'just enough amp to do the job', so 8 ohm wouldn't be a problem anyway.
I do like that you're always thinking outside the box in trying to help us musicians & our obsessive gearitis.

I disagree with your characterizing yourself as the contrarian (guess that make me the pot calling the kettle something!). Imo you just cast a vote for "make it an option". Thanks!

I think that it is a GREAT IDEA for an OPTION..
One pound is not a deal breaker at all.. . PRICE would be more of a consideration to many ..
But since it is an Option that would be up to them to decide if they need it or not. SO I think it would be a great option..

Thanks, yup it's clearly gotta be an option instead of a standard feature on the TC112 and Hathor 1203.

 

[Jeff Moote]

Thank you Tom. Ballpark fifty bucks, it looks like.
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The base price would be bumped up, to cover the additional labor and materials cost. And yes, the math says that in 4 ohm mode, the sound should be just about like the 8-ohm version.
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Thanks, yup it's clearly gotta be an option instead of a standard feature on the TC112 and Hathor 1203.

Sounds awesome Duke! The follow on question is then a) could this be retrofitted to existing TC112 and Hathor 1203s (I assume so, but requiring a driver swap to the 4 ohm?), and b) if so would you need the cab in hand to do it or could the driver and crossover/switch bits be swapped out in the field?

 

[DukeLeJeune]

Please tolerate my ignorance in asking when 4ohm and 8ohm "switches" morphed from trickery, nonsense, and controversial quackery to an effective, real-world option? Or, is this controversy something from overactive, often-trouble-causing imagination?

Excellent question! Either I have a well-paid and highly creative marketing department, or I've discovered alien astronaut technology like what they used to levitate the pyramids.

Actually, it's neither. Just good luck and a close look at real-world numbers and a little math.

First, let's take a close look at some real-world numbers: The actual voice coil resistance of four Eminence "8 ohm" woofers that are used in bass cabs (the inductance matters too, but taking it into account would lead to the same results). Here they are: 5.1 ohms, 5.06 ohms, 5.02 ohms, and 4.83 ohms. These are the voice coil resistance figures for the S2012, Deltalite 10, S2010, and CA10-8 woofers, respectively. The average is 5.0025 ohms. So in other words, a woofer with a voice coil resistance of 5 ohms can safely be called an "8 ohm" woofer.

Now for the good luck: The voice coil resistance of the custom woofer I use in the new TC115 (and Hathor 1505) is 3.9 ohms. Actually that was on purpose... I asked for a "high 4 ohms woofer", so it wasn't really luck.

Finally let's do a little math. 3.9 + 1.1 = 5.0. So if we add 1.1 ohms of resistance in series with our 3.9 ohm woofer, we get a 5.0 ohm effective voice coil resistance, and that meets our minimum requirement for the cab to now qualify as an "8 ohm cab", which can be paralleled with other 8-ohm cabs.

I ran this idea by the head engineer at Eminence, and he told me to use twice as much power handling as the math calls for in the series resistance, to make life easier on the resistors. So in this photo, notice the bank of resistors across the top of the crossover board. Taking that recommendation into account, these resistors should be good to at least 800 watts long-term.

So, assuming this is effective and viable, why not package this in an outboard interfacing device that could be used with applicable cabinets/situations?

What I'm doing is practical for that specific woofer because its voice coil resistance is so high to begin with, and its electrical Q is fairly low. With the switch engaged we still lose about 16% of that cab's input wattage to just heating the resistors, and we raise the electrical Q by 28%, both of which are arguably still live-with-able in this case (we lose a little less than 2 dB of voltage sensitivity and a little less than 1 dB of efficiency with the switch engaged). But if we had to bridge a larger gap by using a higher value series resistance, the losses quickly become untenable and the power handling required of the resistor bank increases as well.

The reason it is imo practical to consider such a switch for the 4-ohm 3012LF is, it's DC resistance is a high 3.89 ohms. So, the situation is almost identical.

I don't think it would be practical to try to design a universal switch. I cut the margins as close as I can, as doing anything less than that carries too much of a penalty, and most "4 ohm" cabs start out too low to begin with... like a cab with two Deltalite 10's in parallel would have a net voice coil resistance of 2.53 ohms.

 

[tombowlus]

As a $50, one-pound option, I think this would be a great idea that some players would really like (but many others may not need).

 

[Smallequestrian]

Hey smperry, looks like we're 2 of the eight!
I own the prototype 1544, I dug mine so much I just couldn't send it back to Duke after beta testing it. I've gigged mine all over town, I love the way it naturally rolls off the deep lows, tames boomy sounding stages and sits in the mix without steeping all over the kick's frequency.

I still have my 8 ohm 1544. Love the cab while gigging, sadly it nor I have seen a gig in a year and a half.

 

[Thumper]

So, would I be better off pairing a 4 ohm Hathor or Thunderchild 12 with my 4 ohm Thunderchild 115? For the record, Duke and I had a 12 + 15 pairing conversation a couple of years ago and he wasn't against the idea. Now that I have a powerfully voiced Roscoe, a 37" Dingwall (ABI), with a 35" coming, and with my new found appreciation for 12" cabs, I really wanrt to do this.

 

[mysteryclock]

I just received my 1855!! I just had a bit of time to try it out but my initial impressions are that this thing is a beast!! Soo much good lows and clarity it's amazing! I was comparing it to my TC 112 and to my ears they don't actually sound THAT different - with the 18 sounding like a bigger brother of the TC with more bottom end, authority and more forward mids/snarl. The 2-5" drivers are amazing for distortion and they also go quite high too so it works well with a modern bass with rounds for a good slap tone! You can definitely hear that both cabs come from the same family - I can't wait to give the 1855 a try at a gig.

It ain't real if I don't post a pic so here you go

View attachment 753577

That is just awesome! And I have a perfectly nice rig right now....I have to keep repeating that to myself....

 

[nutdog]

I vote for the option although I doubt I'll be buying one so my vote doesn't really mean anything.

Usually I'm either not pushing one cab very hard or I know I'll be loud enough to want two. But it would come in handy if you want to use something like a gk mb200 on the single cab gigs.

I think the option would be more useful with the big cabs.

 

[John D Harris]

...

I think the option would be more useful with the big cabs.

This!
For someone who has a pair of 2x12 or 4x10 cabs going from smaller & medium sized venues with one cab as well as big stage loud gigs where you don't want to feel like you're pushing your drivers hard, I can see such a switch being handy.

 

[anderbass]

I still have my 8 ohm 1544. Love the cab while gigging, sadly it nor I have seen a gig in a year and a half.

Cool, and then there were 3 !

Maybe we should start a club or something: A little birdie told me that one of Jon Bon Jovi's bassists owned a 1544 too. So I guess we've tracked down 4 of the 'illustrious-eight' so far...

Its not a Thunderchild, the humble Hathor 1544 is the red-headed Stepchild of Dukes lineup