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Rockford Fosgate T3 19 discussion

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Hi Dave,

 

Don't you think things like impulse response, group delay, power compression, distortion, and inductance related affects change the way things sound even with a matched FR?

 

The RF is significantly better in "all" these "factors"

 

I feel Josh downplayed it but he did say "it does seem like these changes resulted in a much better upper bass range through the crossover region. It definitely seems like there is a better sense of attack and punch on kick drums and sharp upper bass transients when the system is cranked up."

 

I have done enough work with drivers similar to the XXX(and the XXX itself), and with drivers like the RF to concur albeit much more strongly with the differences Josh has noticed, I will agree with the sheer number of drivers and amount of power on hand the differences at normal listening levels would be diminished, but even at that differences are noticeable. On a 1 to 1 basis when driven to limits the difference are Huge, "massive"... and some other descriptive words you may not like...

 

 

Hi Nathan,

 

Can you be more specific with what "driven hard" means in Ricci's room, how same FR can possibly sound different and any of the "many factors that will change the sound" that obviously aren't apparent to me?

In other threads, for example, there is howling and jeering over snake oil salesmanship claims of the benefits of using certain cables, etc., but here the terms "better in every way" and "massive step up in every possible way" are cool?

 

"Massive step up in every way"?

With 80-100 liters of displacement and >20KW of power there is no way to drive either system to the point of reversion to non-EQ'd response in Josh's room unless you purposely do it for no known reason.

He can theoretically raise the crossover if he wishes, although both traces show inaudible differences to 100 Hz. How hard would you have to push them to hear a massive difference?

 

Back when Josh was contemplating buying the XXXs he asked my opinion. I designed a sealed, DO, push/pull box of some 20 cubes net. I mentioned that 10 cubes per driver would be the minimum I would put the XXX in. There's an 8-10dB increase in sensitivity and efficiency <20 Hz with the XXX in >2X the box Josh has them in. Seems a reasonable choice to me to build better enclosures than to spend 10 grand more for drivers and claim "better in every possible way".

 

Josh said his goals were cost no object to see what he could do with the existing small boxes. I agree that he met those goals with happy results. But, to stretch that to "massive step up in every possible way" begs more specific data.

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Points noted, but there simply is no difference in group delay if FR is the same. The 2 (GD & FR) are directly related by a formula. Similarly, there is no power compression or (assuming you mean harmonic) distortion at reference level with XdB of headroom in either system.

 

I concede inductance-related distortion >60 Hz, but simply lowering the crossover point and using mains properly designed to mate with a XXX system is a rather simple solution.

 

Where it counts in a multiple-driver high displacement subwoofer system for Home Theater, <20 Hz, there is little chance the RF driver is even equal let alone a massive step up. You say diminished difference, I say zero difference, lots and lots of experience notwithstanding. And, I'm just not a subscriber to the whole "punchier slam" thing. What we hear is frequency response. When it's matched there is no GD to hear and when you have 8 x 18" subwoofer drivers with multi-KW power, there is no compression, THD or other audible differences.

 

In fact, as I've posted a few times, many listeners over the years perceived high 2HD as presenting a kick drum as being "tighter", etc. Massive step up for those folks?

 

I've got a bit of experience with all sorts of subwoofer drivers myself. You must just have better ears than I and my test listeners have. :)

 

I'm only posting an alternative voice to the constant escalation of system size, cost and playback levels for the average enthusiast, who is quickly becoming lost in this madness of >140dB playback levels and the like. I'm not saying either is "better", just pointing out that there is far more similar in these 2 systems than there is difference, unless more data to the contrary can be shown.

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The reason I changed drivers comes down to the fact that I was never quite happy with the bass through the crossover with the XXX. HT rumbles and all that were fine. I listen to a lot of music and that was where I wasn't quite happy. Chalk it up to any number of factors. I didn't want to lose any displacement switching drivers though. It took 6 years or so to find a driver that did what I was looking for. I was designing the motor for something that would do what I wanted when this one came along finally. It does sound different to me when the system is pushed especially with music. Call it placebo or whatever but all of the measurements show that the 19 behaves much different and offers measurable improvements in almost every front. Those can be said to be inaudible but they are obvious in the measurements. Displacement per dollar is not the be all end all for me otherwise I'd have bought a bunch of Alpine 15 SWS's and called it good. I don't know what my system choices have to do with anyone else.

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Josh,

 

Have you measured the responses of each bass-managed mains channel to see how well the mains integrate with the subs?  I remember when I first EQed my subs to flat, I was very happy until I did my sweeps of the bass-managed mains channels.  Optimizing sub distance was nowhere near enough to get a good blend.  Even with the the ports stuffed and a relatively high crossover, I was still seeing considerable interference from the mains all the way down to 40 Hz.  That's a big part of what led me to put OpenDRC-ANs for DSP on my mains (big improvement!), and now, the Motu A16 + PC DSP with full matrix support.

 

And yeah, one should not underestimate the impact of inductance on sound quality, even when using lower XOs.  Anywhere there are dips in your room response for any one of your mains in the 80-200 Hz range, there's a chance you'll be hearing more sound from your subs than from that mains speaker, despite the 24 dB/octave roll-off.  Having the subs be able to reproduce that sound cleanly does improve sound quality.

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Also like to add that you don't need to bump the master volume by much if at all when pulling down the top end of a driver that is far more sensitive up top than the other. That's excess top end headroom not lack of low end when both have similar low end sensitivity. The 19 has better 10-20Hz sensitivity not worse in this case.

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The reason I changed drivers comes down to the fact that I was never quite happy with the bass through the crossover with the XXX. HT rumbles and all that were fine. I listen to a lot of music and that was where I wasn't quite happy. Chalk it up to any number of factors. I didn't want to lose any displacement switching drivers though. It took 6 years or so to find a driver that did what I was looking for. I was designing the motor for something that would do what I wanted when this one came along finally. It does sound different to me when the system is pushed especially with music. Call it placebo or whatever but all of the measurements show that the 19 behaves much different and offers measurable improvements in almost every front. Those can be said to be inaudible but they are obvious in the measurements. Displacement per dollar is not the be all end all for me otherwise I'd have bought a bunch of Alpine 15 SWS's and called it good. I don't know what my system choices have to do with anyone else.

Not sure why you think any discussion of a comparison of your systems relates to what your choices have to do with anyone else. This personal crap is annoying.

 

I just wanted to comment on the idea that the difference is massive in every way. It isn't. I guess it isn't open for discussion, which is fine by me.

 

Good listening, Josh, et al.

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Damn Dave. You sure seem up tight. I thought it would be nice to let others see a bit of my thought process behind the driver choice/change and why I was looking for something else anyway. I never said the differences were massive but there are differences. The discussion is about the driver right? Somehow my impressions of using the drivers and the measurements that I have are off topic or something?

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The 2nd harmonic distortion is lower along with the rest of em so that isn't what I'm hearing with music. It's likely the extra 10dB of top end headroom, less THD, less radical EQ and perhaps less compression all taken together. I've heard Tom D. talk about rapid onset compression of peaks before and never put much stock in it before but I'm starting to wonder after listening to more types of drivers over the years. Like I said maybe it's placebo. That wasn't a smart ass comment. But the measurements do indicate a lot of differences.

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Thanks for the video. I was just assuming the motor used magnets in the pillars rather than the pole. Seems I was wrong. I'm glad he showed the surround attachment method a bit. I'm thinking about taking one of these apart but I also don't want to screw up a $1250 driver.

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Yeah,for that kind of money I would settle with the video.

They say it uses over 3 Kgs of magnet and that got me thinking that it couldn't all be only in those pillars. The "flower power" arrangement for the magnets looks good but are a little inefficient, from what I know.

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Pole placed mags are usually unable to produce as much magnetic flux due to limited surface area. Clearly you can still do a lot with them but you can get more from the outer surfaces due to more area being available. However that = more cost and space. Where did you get the 3kgs of neo magnet information? I've not heard or read that. That is a LOT of NdFeb. Possibly they have pole material and outer mag material in the pillars? However the guy in the video said a single huge NdFeb slug in the pole area. I would love to see the 3D models of this driver but I doubt they'll be sharing those if I ask for them.

 

The motor appears to bolt on to the top assembly but the screw placement is difficult to get to and seems like an odd size as well. I think I know what's going on in there but I'm still a bit leery about taking one apart. I did figure out that the surround clamp ring has the screws hidden under the gasket.

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I got the number from here :-P

http://www.rockfordfosgate.com/products/details/t3s1-19

Right at specs. :-) easy to miss if one doesn't look.

There is a video on youtube with a better drawing but it is not a clear 3d model.

 

That didn't used to be in the specs from what I can remember. They seem to keep revising and adding to the information released. Some of the videos they've posted I don't remember either. That is an absolute huge amount of neo. 7+ lbs??? :o

 

By the way if you dig around you can find these for under $1500 shipped. Still super expensive but over $1000 under MSRP is a significant savings.

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Dig around as in find someone who is not charging full retail price. Might need to send some emails or pick up a phone and talk to a real person.

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Josh, I'm not sure if this has been asked but how the heck does this thing beat out 18" and 21" woofers with even far more sensitivity even at the upper bass frequencies like 60Hz? Including the BC21SW152, Pro5100 and BMS18N862? It matches or bests all those at 60 and just obliterates them below 60  :o

 

And It embarrassed the LMS5400 from pretty much  20Hz on up and the RE XX only hangs from 20 to 30hz. This thing has set a new bar, damn...I never figured a moving mass of 1Kg could do that!

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Josh, I'm not sure if this has been asked but how the heck does this thing beat out 18" and 21" woofers with even far more sensitivity even at the upper bass frequencies like 60Hz? Including the BC21SW152, Pro5100 and BMS18N862? It matches or bests all those at 60 and just obliterates them below 60  :o

 

And It embarrassed the LMS5400 from pretty much  20Hz on up and the RE XX only hangs from 20 to 30hz. This thing has set a new bar, damn...I never figured a moving mass of 1Kg could do that!

 

Good question...Couple of reasons.

 

#1. I switched from the K10 amp to the more powerful K20 amp. The K20 should have about 1 to 1.5dBW higher burst output.

#2. Some of the pro style drivers are failing for distortion or even bottoming out at 50-80Hz and this limits the SPL. 280volts+ is not a joke. No issue for this driver.

#3. There are things that start to happen at those types of very large signal input levels that are different from what the small signal data suggests might. Current induced distortion gets out of hand in some drivers, others lose linearity in the suspension and /or motor and the effective motor force and efficiency drops off greatly at higher output levels. All of this can cause compression of the output so that by the time you are hitting the driver with 250 volts its performance has shifted greatly from what it was at 2.5 volts. Once the power levels get high enough you're no longer getting a full dB from the speaker per dB of signal increase. It may be a half dB or even 0.3dB. This isn't only something related to thermal heating or excursion. I see this all the time with the burst tests where thermal heating is not a factor. The RF compresses less and exhibits less behavior change with strong input signals than most other drivers. Beastly strong motor helps with the huge MMS.

#4  Magical Super Woofer Dust (Trademark of Simonian's California Bass Blingers)

 

 

For example look at the 21SW152 sealed test burst graph under static images. It is distortion limited at 50Hz and then mechanical limited before the amp runs out of gas and that was with the old K10 amp with less burst potential. The driver is actually being run out of xmax at 50Hz. Check out the 21LW1400 also. That driver is way more sensitive and efficient than the 19 but it folds up shop way sooner as well.

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In a sealed burst test, I think other important factors besides excursion and thermal compression,are the break-up of the diaphragm, the softness of the adhesives and other small factors that doesn't have an effect at small signals but once you push ove a threshold, those effect starts to accumulate with other nonlinearities.

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Good question...Couple of reasons.

 

#1. I switched from the K10 amp to the more powerful K20 amp. The K20 should have about 1 to 1.5dBW higher burst output.

#2. Some of the pro style drivers are failing for distortion or even bottoming out at 50-80Hz and this limits the SPL. 280volts+ is not a joke. No issue for this driver.

#3. There are things that start to happen at those types of very large signal input levels that are different from what the small signal data suggests might. Current induced distortion gets out of hand in some drivers, others lose linearity in the suspension and /or motor and the effective motor force and efficiency drops off greatly at higher output levels. All of this can cause compression of the output so that by the time you are hitting the driver with 250 volts its performance has shifted greatly from what it was at 2.5 volts. Once the power levels get high enough you're no longer getting a full dB from the speaker per dB of signal increase. It may be a half dB or even 0.3dB. This isn't only something related to thermal heating or excursion. I see this all the time with the burst tests where thermal heating is not a factor. The RF compresses less and exhibits less behavior change with strong input signals than most other drivers. Beastly strong motor helps with the huge MMS.

#4  Magical Super Woofer Dust (Trademark of Simonian's California Bass Blingers)

 

 

For example look at the 21SW152 sealed test burst graph under static images. It is distortion limited at 50Hz and then mechanical limited before the amp runs out of gas and that was with the old K10 amp with less burst potential. The driver is actually being run out of xmax at 50Hz. Check out the 21LW1400 also. That driver is way more sensitive and efficient than the 19 but it folds up shop way sooner as well.

 

 

 More or less my suppositions. The thing just deals with compression so much better than most drivers, essp. the pro drivers. I'm guessing for mere mortals that can only put 2-3k on a woofer -- a high end pro driver would be a better option. but holy smokes this thing has headroom. The problem with the B&C drivers is that while they have impressive SPLSens, they fall flat on their ass at high power because they have such short coils. Even the iPAL only had a ~1.7" long coil or so for the 18". My guess is this is why it didn't work well for you.

I don't want to knock the RF in anyway, but I do believe that the DD motor plays less of a role in its performance and its more just a crap load of magnet with a very robust suspension. To me, this is what the XXX should have been. I think this driver has over double the BL of that driver :o

 

to me, BL^2Re is light horsepower (albeit it a non-linear scale). A driver with 500 and this kind of stroke is freaking impressive . The new bar is 600/700 :)

 

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I never figured a moving mass of 1Kg could do that!

 

Don't be mentioning that on some of the 'audiophile' forums, they'll cry 'Heresy!!', round you up with pitchforks, burn you at the stake, then return to a nice dinner listening to their single 10" because, you know, 10s are lightweight and 'fast' ;)

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