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Author Topic: JTR releases new 2x18 Subwoofers - info here  (Read 7596 times)

Steve Litscher

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JTR releases new 2x18 Subwoofers - info here
« Reply #10 on: August 19, 2018, 12:58:33 pm »

Answering a couple of questions from above:

- I like the direct radiating design over the OS. The OS is amazing with what it can achieve from a single 18 driver, and it sounds darned good. But the extra delay and some node cancelation challenges in certain environments and configs had me wanting to go direct radiating. Granted, direct radiating isnt a magic wand, but its a little less fussy in specific situations.

- The amps have full DSP, including limiting. Jeff programs them and thoroughly tests them prior to shipping. SpeakerPower has pretty decent processing in their active units - weve been using the C212Pro for about a year; they have the SpeakerPower amps with DSP as well - no complaints.

- Output at 27Hz; I rarely run anything below around 35-36Hz, but knowing Jeff, if he says 27Hz, I trust that the speaker has usable output at that frequency. If Jeff does anything, its over deliver and under promise. :-) Im not a gambling man, but my bet would be that 27Hz is +/- 3dB. Jeff would know for sure.


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Lance Hallmark

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Re: New JTR subwoofer - 2x18 HO
« Reply #11 on: August 20, 2018, 03:34:04 pm »

The following is a general statement, and is not inferring or referencing any of the products in discussion, It is for general information and consideration.

The useful output of any loudspeaker is a combination of extension and sensitivity and power handling.

A simple number ( goes 10Hz lower) doesn't tell anything about how loud it is at that freq.

The -3dB or -10dB etc MUST be referenced to SOMETHING or else it has NO meaning.  It should be referenced to the sensitivity to have any valid meaning.

But sadly, there are plenty of examples of top manufactures whos own graphs and simple number spec sheets are VERY wrong.  I have some that are more than 20dB off.  that is only a factor of 100.  What if your pay check was off by 2 zeros?  I bet you would care THEN.  HA HA

ANY loudspeaker EVER made, including soft dome tweeters, can EASILY reproduce 1Hz.  So every loudspeaker goes down to 1 Hz.

Now how LOUD they are at 1 Hz is a TOTALLY different story.

You MUST know more information than a simple number.

Simple numbers will get you trouble every time.

My bad, it is listed on the web site

Frequency +/- 3db
27-190hz (tuned to 27hz), active version
Sensitivity (half space)
103db, 1 watt, 1.41 volt, 2 ohm (half space)
Usable Output
138db (Calculated peak 141db 3db compression)

I sometimes put an answer out quickly without attention to detail - too much time on about every other dumbed down social media site & forum. It is that attention to detail and how important those details are for true knowledge and understanding that I love about this forum, I apologize for lowering the bar sometimes which is why I am here mostly to learn.
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Lance Hallmark
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Chamsys, Crown, Danley, EV, JTR, Powersoft, Yamaha

John Schalk

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Re: New JTR subwoofer - 2x18 HO
« Reply #12 on: August 20, 2018, 04:56:47 pm »


Sensitivity (half space)
103db, 1 watt, 1.41 volt, 2 ohm (half space)

I am considering driving each speaker separately so how do I translate the single 2 ohm sensitivity spec into two 4 ohm loads?  I understand 2.83 for 8 ohms, 2.00 for 4 ohms, and now 1.41 for 2 ohms but I'm lost when it comes to going from a single load to dual loads.
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Art Welter

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Re: New JTR subwoofer - 2x18 HO
« Reply #13 on: August 20, 2018, 08:02:04 pm »

I am considering driving each speaker separately so how do I translate the single 2 ohm sensitivity spec into two 4 ohm loads?  I understand 2.83 for 8 ohms, 2.00 for 4 ohms, and now 1.41 for 2 ohms but I'm lost when it comes to going from a single load to dual loads.
Increasing from one to two "loads"  (driver/enclosure) increases sensitivity by 3dB.

Two drivers/enclosures each of 100 dB sensitivity would be equal to one dual driver/enclosure of 103 dB sensitivity. The one watt one meter sensitivity, (2.83V into 8 ohms, 2.00V at 4 ohms, 1.41V for 2 ohms) for the pair of drivers remains the same whether driven by one or two amplifiers.




« Last Edit: August 20, 2018, 08:07:51 pm by Art Welter »
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John Schalk

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Re: New JTR subwoofer - 2x18 HO
« Reply #14 on: August 20, 2018, 10:58:07 pm »

Increasing from one to two "loads"  (driver/enclosure) increases sensitivity by 3dB.

Two drivers/enclosures each of 100 dB sensitivity would be equal to one dual driver/enclosure of 103 dB sensitivity. The one watt one meter sensitivity, (2.83V into 8 ohms, 2.00V at 4 ohms, 1.41V for 2 ohms) for the pair of drivers remains the same whether driven by one or two amplifiers.

Thanks for trying to help me Art, but I'm still not sure I understand.  I would like to know what the calculated output of this sub will be if I power it with two amp channels that produce 1250 watts @ 4 ohms.  Can I simply add the two channels together (2500 watts) and then use the supplied 103 dB sensitivity spec and do the math?  If so, I come up with an output of ~137 dB which is pretty close to Jeff's usable output spec of 138 dB.  Did I do that correctly?
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Art Welter

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Re: JTR releases new 2x18 Subwoofers - info here
« Reply #15 on: August 20, 2018, 11:24:38 pm »

Yes, an output of ~137 dB would result at the frequencies that reach the 103 dB sensitivity specification with each 4 ohm driver powered with ~1250 watts, same as an amp capable of 5000 watts into two ohms for the pair.


« Last Edit: August 20, 2018, 11:53:24 pm by Art Welter »
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Dan Mortensen

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Re: JTR releases new 2x18 Subwoofers - info here
« Reply #16 on: April 14, 2019, 02:26:59 am »

I've looked with interest at the JTR powered stuff, and there are a few things I don't understand:

1) Why IEC and not Powercon?

2) Why an on/off switch that can get shut off by mistake?

3) Why are there knobs on it at all? All user adjustable processing for the gig should occur in the console or drive rack. IMO.

4) Any knob can get sheared off in transit.

5) Same for the little toggle switch "Auto" vs. something.

6) What provision is there for using them in the rain and having them continue to work?

I like the idea of lightweight subs (thinking of the 212 Captivator), but every one of those aspects is a deal-breaker for me.

Full disclosure: I think Meyer has all that right for powered speakers and I'm a dealer for them but use different subs for other reasons.

Edit: After writing this, I found another thread about Captivator 218's (I think) where people talked about the reasons why the amps are this way. While that was interesting, it doesn't change the fact that they are this way and therefore difficult to want to use.

FWIW I feel the same way about the amps in Behringer self-powered speakers and am a dealer for them, too, but live mostly in their mixer world. Haven't sold any speakers...
« Last Edit: April 14, 2019, 04:17:50 pm by Dan Mortensen »
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Ron Ventour

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Re: JTR releases new 2x18 Subwoofers - info here
« Reply #17 on: April 28, 2019, 07:51:41 am »

I've looked with interest at the JTR powered stuff, and there are a few things I don't understand:

1) Why IEC and not Powercon?

2) Why an on/off switch that can get shut off by mistake?

3) Why are there knobs on it at all? All user adjustable processing for the gig should occur in the console or drive rack. IMO.

4) Any knob can get sheared off in transit.

5) Same for the little toggle switch "Auto" vs. something.

6) What provision is there for using them in the rain and having them continue to work?

I like the idea of lightweight subs (thinking of the 212 Captivator), but every one of those aspects is a deal-breaker for me.

Full disclosure: I think Meyer has all that right for powered speakers and I'm a dealer for them but use different subs for other reasons.

Edit: After writing this, I found another thread about Captivator 218's (I think) where people talked about the reasons why the amps are this way. While that was interesting, it doesn't change the fact that they are this way and therefore difficult to want to use.

FWIW I feel the same way about the amps in Behringer self-powered speakers and am a dealer for them, too, but live mostly in their mixer world. Haven't sold any speakers...

Got a link for that other cap 218 thread?
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Steve Litscher

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Re: JTR releases new 2x18 Subwoofers - info here
« Reply #18 on: April 29, 2019, 11:04:53 am »

I've looked with interest at the JTR powered stuff, and there are a few things I don't understand:

1) Why IEC and not Powercon?

2) Why an on/off switch that can get shut off by mistake?

3) Why are there knobs on it at all? All user adjustable processing for the gig should occur in the console or drive rack. IMO.

4) Any knob can get sheared off in transit.

5) Same for the little toggle switch "Auto" vs. something.

6) What provision is there for using them in the rain and having them continue to work?

I like the idea of lightweight subs (thinking of the 212 Captivator), but every one of those aspects is a deal-breaker for me.



All of these questions can be distilled down to a single answer: economy of scale.

Jeff is a small, single-man operation and has to make decisions about where he can streamline production and save on costs. His amplifiers are made by SpeakerPower in California, and he had them cut/build a common amplifier plate for his product line.

He's huge in the Home Theater world, and I'm guessing the majority of his sales are HT-related. He's gaining traction in the Pro Sound world, but it's a long, arduous road. As such, when he spec'd his plates from SpeakerPower, he did so more for the HT world.

I've asked him a number of times for PowerCon, flat switches, and whatnot. He can do it, but it's extremely pricey, and he's sitting on a large inventory of amp plates that were already made-up in their current config.

Regarding rain... I've used his stuff in the rain without issue. As is the case with nearly any active speaker, a good set of rain covers or rain shields are critical.

Dan Mortensen

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Re: JTR releases new 2x18 Subwoofers - info here
« Reply #19 on: April 30, 2019, 04:00:42 pm »

Got a link for that other cap 218 thread?

Nope, sorry, IIRC I did a search for the 218 and found a thread somewhere else, so you could find it, too?

But now the post below essentially says the same things that I thought I saw in that mysterious other thread.



All of these questions can be distilled down to a single answer: economy of scale.

Jeff is a small, single-man operation...


Regarding rain... I've used his stuff in the rain without issue. As is the case with nearly any active speaker, a good set of rain covers or rain shields are critical.

I deeply understand and appreciate the limits of being a one man operation. I have emailed Jeff and promptly received back complete and clear replies, and appreciated that, too. However, my points in the post you quoted still stand.

Regarding the rain covers, the covers I've seen have been nylon, and I presume the amp modules generate heat. Don't they melt nylon if in direct contact?

The rain shields I've seen are made of stiff plastic or metal and bolt on with ventilation, but I'm not in a mood these days to design and build something like that which would indeed protect the modules from weather and handling, but which would add depth to an already deep box (aren't the 212's 3' deep when in use? And the 218's as deep if not deeper? I confess that after making a decision not to look further into them, that info has exited my brain) if the shields were left on permanently, and if left off expose an amp module with protruding switches and knobs, or maybe one of each, to damage that I'd then have to design something to protect that situation.

These boxes seem like they'd be fine for unpowered use, but then in my specific case I'm replacing something I already have and like which works fine (old unpowered Bag End double 18's) with essentially the same thing, except I've spent $10,000+ to do so and get enough of them.

If I didn't already have a solution, these boxes do seem better in that they're lighter and newer technology.

YMMV, of course.
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Re: JTR releases new 2x18 Subwoofers - info here
« Reply #19 on: April 30, 2019, 04:00:42 pm »


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