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Rockford Fosgate T3 19 discussion

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All I can say is that it is a very cool looking driver. I would be tempted to mount it with the motor out of the cabinet.

Personally, I thought it was a work of art and seems to perform like one too. And I had the same thought about mounting it inside out or with plexiglass if I were to use one. A tall column with the sub mounted inverted would look like a stand with a piece of art on top. :)

 

I'd really like to know who developed it as my first thought was who did Rockford hire.

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It certainly looks cool but...

 

As a candidate for HT, it's mounting depth is prohibitive and, as with any sub driver design, the higher the motor strength, the lower the Qts. It's Q is so low, it never achieves a 2nd order roll off.

 

The HS-24 trounces it for 1/2 the price and has far less disparity between the bottom frequencies and cross. A quad of HST-18s in dual, dual-opposed boxes is a far better system for the same dough...

 

Etc., etc.

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It certainly looks cool but...

 

As a candidate for HT, it's mounting depth is prohibitive and, as with any sub driver design, the higher the motor strength, the lower the Qts. It's Q is so low, it never achieves a 2nd order roll off.

 

The HS-24 trounces it for 1/2 the price and has far less disparity between the bottom frequencies and cross. A quad of HST-18s in dual, dual-opposed boxes is a far better system for the same dough...

 

Etc., etc.

 

Its price tag alone make it a driver that few will ever purchase, but it has a few specifications that really stand out for some specific, and I'll admit rare, use cases. 

 

The tremendous BL has the horn guys salivating as the possibilities, and its thermal handling capabilities look to surpass just about everything else out there as well. 

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Shoot...It is exactly what I've been looking for. Different strokes for different folks. I've slowly gravitated towards low q drivers and sealed systems over the years. The problem is most of the drivers don't have enough displacement. This one does. With enough motor you achieve slightly better than 12dB octave rolloff. Less steep, not more. If you compare this with other drivers in the same box you can see this effect below 30Hz. Drivers with lower motor strength per unit of cone area have a hump in the response and a sharper than 12dB octave roll off over some parts of the bandwidth. Drivers like this are slightly shallower slope in final roll off. The F3 ends up much higher but that is irrelevant. I prefer that. That is the effect of much better efficiency and ends up being much higher headroom, efficiency, sensitivity, etc. Less power demanded from the amp and better headroom with complex signals. The 24 is very cool no doubt but not enough motor for me. Needs a big boy motor. BHS is a step in the right direction. Boxes are too big for me to run it as I would want to. I'm running a pair of these RF's in a box about the size of Dgage's single 24 and the system qtc is extremely low, near IB. I don't see how mounting depth is prohibitive either. Yeah it's REALLY deep but it will still go in a box 19" deep without issue. Mounting depth needs 16". I don't see many people building 18" drivers into boxes that are less depth than that.

 

 

I'm working on getting the system back up and running today and here is the raw at the seat response with no smoothing and no signal shaping. The LPF is in line. This is a much better starting point than the XXX's, which exhibit the typical inductance and high qtc hump which exacerbates my room issues.

 

 

post-5-0-20566600-1448746428_thumb.jpg

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Something funky happened to the SPL numbers for this driver in the systems list.  They're all blank. 

 

 

That's very odd. The data was missing. Not sure how that happened. It's been uploaded. Should be there now.

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At the outset, I've never been a fan of the XXX drivers. Way too big, way too big a box requirement, way too much $$$. Looking more at the HST-18/UXL-18 is more my speed.

 

There's not much difference as far as what EQ is required to get flat in your room. It's simple enough to project the HST-18, for example from anechoic to same placement of driver/mic you used to generate the in-room graph posted earlier:

 

3DzjtHi.png

 

Done quickly, but I'm not gonna be too far off. A typical humped response (part inductance/part small box) is down around -7dB @ 20 Hz, whereas the low Q drivers are down more like -15dB @ 20 Hz. Pull down the hump of the long throw mid q driver or pull down the top end of the mega-motor low Q driver. A wash in the end, IMO.

 

You're showing tons of room gain. Since the Fosgate is down -25dB from cross to 10 Hz

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There's a bunch of ways to skin the cat. Lets be honest here 8 of the HT15's or 18's like we heard at Brandons place are overkill already, unless you are well past any sane playback level. I've been interested in pushing the limits of what you can get from a certain amount of volume with cost be damned for a long time. Most of my designs including my horns are along that train of thought.

 

I always liked the xxx's simply because they could be beat on with a severe amount of boost and you really didn't have to worry about the excursion. The amp almost always gave out first. Every other driver I tried wasn't quite there. Then the new Sundown parts came out, but that was well after I had the x's. Probably would have went with something based on their team or Nightshade platforms if they'd have been out at the time. Anyway there's nothing budget or perhaps practical about the bass systems I use. I never recommend them to others.

 

The room gain is certainly there but the amount is a bit deceiving. There is a large amount of gain below 15Hz and also at the 43Hz peak. Up top it is actually a bit of a net loss. Still there is a ton under 20.

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I love that line of thinking Josh.  Hopefully you'll have the system running within the next few months so I can come up and hear it this spring.  Should be breath taking.

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This driver is pure sex...technologically speaking. Great for horn guys for sure. Priced out of sight for guys looking for the next "bargain" woofer and it should be bc it's absolutely killer in every aspect. Thanks for the measurements Josh and also thanks for bringing it to the GTG. :)

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Josh, what will you use to EQ your subs if anything?  If you get a chance on your next measurement session will you show the close mic next to the LP response?  That is some wacky looking room gain below 10Hz. 

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Josh, what will you use to EQ your subs if anything?  If you get a chance on your next measurement session will you show the close mic next to the LP response?  That is some wacky looking room gain below 10Hz.

 

DSP is built into the amplifiers. Advanced stuff can do custom Bi-quads, limiters, etc...Detailed literature if you are more interested is at PS website.

 

Signal chain is PS3 source, Onkyo 886P preamp, K20 amps currently.

 

 

I did a very rough EQ last night. 4 filters. They need optimized better. I just wanted to listen to the bass system after working on it for 2 months straight and most of this weekend, so I called it good and watched Avengers Age of Ultron RB'd and Kon Tiki last night.

 

post-5-0-14063700-1448825265_thumb.jpg

 

 

 

Here is about what the room gain profile translates to compared to ground plane. I've tested about 10 powered systems in room versus ground plane and the average gain in output at 20Hz is roughly 3 to 4dB to the LP. This should be close. Tons of gain below 15Hz.

 

post-5-0-51416100-1448825358_thumb.jpg

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Here is about what the room gain profile translates to compared to ground plane. I've tested about 10 powered systems in room versus ground plane and the average gain in output at 20Hz is roughly 3 to 4dB to the LP.

attachicon.gifGP VS IN ROOM.jpg

I was curious about how a close mic (1" on axis)  in room compared with your ground plane measurement.  You are just about the only guy I know who can compare this accurately (or that I would trust to.)

 

Good response so far anyway.  How does it sound compared to before? 

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I'll see what I can do next time I pull the rig out.

 

Only listened for a bit so far. Sounds basically the same as before. Perhaps a little better through the crossover but I haven't pushed it at all yet.

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I mostly agree with Dave here.  While higher motor strength and higher Qts is a big benefit, all else the same, for the cost it just doesn't make sense to me.  Only if I was highly constrained by both size and available power would I look its direction.  Most likely, adding an additional amp and additional cheaper drivers (with smaller mounting depth so I can fit them all in the box) to distribute the power across would be a much more productive use of my money and would have the added benefit of demanding less excursion (less suspension related distortion) for the same output.

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I mostly agree with Dave here.  While higher motor strength and higher Qts is a big benefit, all else the same, for the cost it just doesn't make sense to me.  Only if I was highly constrained by both size and available power would I look its direction.  Most likely, adding an additional amp and additional cheaper drivers (with smaller mounting depth so I can fit them all in the box) to distribute the power across would be a much more productive use of my money and would have the added benefit of demanding less excursion (less suspension related distortion) for the same output.

 

 The bolded part just about covers it exactly. I don't care about cost much...Size and placement is very much constrained. Not sure how a 240v home run and 2 of the most powerful amps one can buy is a power constraint though. I have no desire to add even more amps for power or wire up something like 16 15's's or 32 12's and have cabs that weigh 500lbs in my house.

 

Clearly this isn't a type of driver for every app or everyone. Thankfully we have a large selection of choices to fit everyone's personal preference.

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Cool graphs Bosso. Yep I've got about 12-15dB of gain by 10Hz. 6-8Hz is the sweet zone. Tons of gain there. I find that bump interesting as it has shown up in numerous room measurements I've seen from different rooms. I already had all the displacement I needed previously and the flatness of the natural room response below 40Hz is awesome. My problems have always been related to the hand off region between the subs and mains and the kick drum area. Believe it or not I ran out of headroom in that area quicker than I'd like. I was having to cut the middle bandwidth of the XXX's by a lot to flatten the response which put a lot of power into them in the 60-100Hz range with music. 43Hz peak is the placement of the seating position. Not willing to do anything there.

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Clearly this isn't a type of driver for every app or everyone. Thankfully we have a large selection of choices to fit everyone's personal preference.

Feel like I've said this a lot lately but.... the best value (sub driver or bass system) does not mean it's the "best".

It takes all kinds and I like it like that. Who all wants to own the same system? I don't.

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