Faital 18FH500 in place of Dayton PA460 for VBSS Style Sub - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 16 Old 09-26-2016, 08:45 PM - Thread Starter
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Faital 18FH500 in place of Dayton PA460 for VBSS Style Sub

Hey guys,

I am thinking in the next couple of months I will be putting together 4x 6cf or so boxes and using some Faital 18FH500 drivers, they are the same price for me as the PA460's as I am in Australia and I can get the Faitals really cheap.

Bassbox Pro says they are almost identical to the Dayton PA460 drivers, in fact, they have slightly better response above 30hz and pretty much identical below it. So they should be a good swap in for the VBSS subs if anybody can also get the Faitals easier.

Dayton: http://www.parts-express.com/dayton-...oofer--295-036
Faital: http://www.parts-express.com/faitalp...-ohm--294-1300

I am not going to follow the VBSS build closely, I will be kind of winging my own design with a slotted port, but I guess the theory will be more or less the same.

Here is the Faital 18FH500 in Red, and the PA460 in White. ~6cf 15hz tune.



The Faital has a 17.5mm Xmech and 9.5mm Xmax, so I am thinking 350w per box will be just fine.

Now, just so I have this right. Are you guys with the VBSS subs basically flattening out the response at say 17hz for eg and throwing away all the extra sensitivity available, but basically taking advantage of the fact that the woofers will be barely heating up when pushed hard in the mid bass?

Obviously this does not look anything like a flat sub response. So, what is the EQ doing as per the VBSS iNuke settings? Is it boosting the low end, or cutting everything above tuning freq to attain a flat response?

Am I right, seeing as its about 105db at 17hz, that if I have four of them constructively combining I should be looking at 117db of output at 17hz/ 350w per woofer? If I flattened the reponse at 20hz, it would be 108db, so, +12 (for 4 boxes) would then be 120db at 350w per woofer before any room gain comes into play?

Am I on the right track here?

Cheers!
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post #2 of 16 Old 09-28-2016, 09:55 PM
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I didnt think the 18FH500 was that cheap but thats great if it is. And the response shape looks about the same as the 460 so I would lean towards cutting and boosting only the low end a bit. BUT this would have to be measured in room of coarse. If you boost according to outdoor measurements then you will only have a small amount of spl up top do to boosting so much down low.
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post #3 of 16 Old 09-30-2016, 06:53 AM
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15 hz tune? That is crazy low for these drivers. I'd go like 25 hz lowest

The faital looks like it's at least twice the price of the Dayton
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post #4 of 16 Old 09-30-2016, 07:45 AM
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6 cu.ft. isn't nearly enough volume for that driver for a vented sub application. To see what I mean, try modelling it in 12 cu.ft you will get a much flatter response. I haven't looked closely but I will bet that if low end extension is your criterion, you will get more low end from 2 drivers in 2 12 cu.ft. boxes than with 4 drivers in 4 6 cu.ft. boxes. Like Bassment said, a 20 or 25 hz tune will work better than 15 hz. Tune it too low and the output rolls off excessively towards the low end. Tune it just right to match the room gain and boundary support, specific to your room, and it will come flat without need for low end boost.
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post #5 of 16 Old 09-30-2016, 09:44 AM
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To get a flat response to 15-20hz, the box will have to be 12-20cuft per cone.
These drivers are really only suited for a 37hz tuning in a small-ish box, otherwise you'll get a first-order roll-off way higher than tuning as per your above charts... which will have to be flattened with EQ (if you want to...)

You'd be better off spending $200 on a conventional car-subwoofer for a 15hz tuning, and two PA drivers with a 40hz tuning. Both optimized for a flat response via the box modelling software. You'll get more output at 12-40hz that way using "car" subwoofers, and also still retain "heat-free" mid-bass via the PA drivers from 40hz up.

That is exactly what I do. [Except I use horned and sealed.]
40hz-1000hz via sealed PA drivers (~100db per watt)
12-40hz via HzHorns (~95db per watt)
DC to 120hz via sealed 21's and LMS-18's and UM-15's (~90db per watt) [The least efficient box design and drivers, but they extend to single digits, unlike ported and horned.]

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post #6 of 16 Old 10-04-2016, 05:08 PM - Thread Starter
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Quote:
Originally Posted by chrapladm View Post
I didnt think the 18FH500 was that cheap but thats great if it is. And the response shape looks about the same as the 460 so I would lean towards cutting and boosting only the low end a bit. BUT this would have to be measured in room of coarse. If you boost according to outdoor measurements then you will only have a small amount of spl up top do to boosting so much down low.
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Originally Posted by Bassment View Post
15 hz tune? That is crazy low for these drivers. I'd go like 25 hz lowest

The faital looks like it's at least twice the price of the Dayton
Nope, I am a Faital wholesaler and my price is no different to the Daytons by the time I get them to my door.

I am basically looking at replicating what is being done with the VBSS subs, when I have four of them constructively combining I should be looking at around +12db of gain, which puts the 17hz levels up above reference. Putting the tune freq too high at around 25hz then makes excursion sky rocket at around 17hz and under so doing it this way actually keeps the excursion lower.

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post #7 of 16 Old 10-04-2016, 05:24 PM - Thread Starter
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Quote:
Originally Posted by BassThatHz View Post
To get a flat response to 15-20hz, the box will have to be 12-20cuft per cone.
These drivers are really only suited for a 37hz tuning in a small-ish box, otherwise you'll get a first-order roll-off way higher than tuning as per your above charts... which will have to be flattened with EQ (if you want to...)


You'd be better off spending $200 on a conventional car-subwoofer for a 15hz tuning, and two PA drivers with a 40hz tuning. Both optimized for a flat response via the box modelling software. You'll get more output at 12-40hz that way using "car" subwoofers, and also still retain "heat-free" mid-bass via the PA drivers from 40hz up.
Not looking to have a flat response from the tuning freq using only the box size without EQ, I am actually looking to EQ these pretty much flat at the lowest freq using iNukes software (Same as VBSS subs are done- I don't need 130+ decibels output but I would like the low thermal and power req benefits of it) , so I was thinking 17hz or so. This is how the VBSS subs work no?

Interestingly, if I were to add in a Dayton UM18 in the very same box model, the 17hz freq SPL level for a given wattage is identical. These drivers are 2.5x cheaper almost than a single UM18 by the time I have them delivered especially since a single UM18 weighs almost 4x a single Faital FH500 so shipping cost is a consideration.

My number one priority is the smoothest room response at the tuning freq (After EQ'd flat with iNuke) at reference level while using the lowest possible wattage requirements. So 4x 18s will only need to draw 1400w to do that which is less than a single UM18 would require and I get all the benefits of room response smoothing by using 4x subs placed around the room.

I have actually slightly revised this to be 6.8cf enclosures. By the way, the volumes are the calculated net internal volumes. So this is actually a ~7.5cf box overall.

Nets 107db at 18hz. With four boxes hopefully constructively combining that would mean 119db/1m. And 120.5db at 20hz.

I don't see how this differs from the VBSS sub design, I just wanted to use different drivers, since I prefer neo magnets and the build quality of the Faitals.

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post #8 of 16 Old 10-04-2016, 05:28 PM - Thread Starter
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Pink is 25hz tune, Red is the 15hz tune.

Have a look what happens to the excursion with the 25hz tune. Its basically useless under 20hz. Cone excursion becomes 17.3mm at 15hz vs only 6mm with the 15hz tune.



And in Yellow, there is the Dayton Ultimax 18.


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post #9 of 16 Old 10-04-2016, 05:37 PM - Thread Starter
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And finally,

Red is 6.8cf net internal.

Pink is 12cf net internal

Green is 20cf net internal

I'm only gaining 3db going from 6.8cf to 20cf. Hardly seems worth it. Plus I definitely don't have the room for that


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post #10 of 16 Old 10-05-2016, 07:18 AM
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The scaling on those graphs is wack, you are zoomed way out.



This is 30 Hz (dark green) vs 15 hz

You also don't have high pass filters on them..
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post #11 of 16 Old 10-05-2016, 07:55 AM - Thread Starter
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Quote:
Originally Posted by Bassment View Post
The scaling on those graphs is wack, you are zoomed way out.



This is 30 Hz (dark green) vs 15 hz

You also don't have high pass filters on them..
Still looks like the 15hz tune is better for what I am after. The 30hz tune looks horrible. I said it before, I am following the VBSS style here in the fact that this is going to be EQ'd at the lower freq I decide (The Dayton PA460 models identical to this Faital driver so I don't see how it differs in a negative way) I am going to be using four of them, I am not after 122db peak from each individual sub. I will EQ flat the response from somewhere just a hair under 20hz and then with four combined I should end up about 119db at just under 20hz at 350watts a piece, 1400watts total. I could feed these 600 watts each, but the excursion starts to become an issue under 20hz.

Why have you put a high pass on the plot? Where did you put it and how much? Obviously I would do that with the iNuke, but I would base that off what the excursion is plotting like.

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post #12 of 16 Old 10-05-2016, 08:06 AM
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Quote:
Originally Posted by Javs View Post
Still looks like the 15hz tune is better for what I am after. The 30hz tune looks horrible. I said it before, I am following the VBSS style here in the fact that this is going to be EQ'd at the lower freq I decide (The Dayton PA460 models identical to this Faital driver so I don't see how it differs in a negative way) I am going to be using four of them, I am not after 122db peak from each individual sub. I will EQ flat the response from somewhere just a hair under 20hz and then with four combined I should end up about 119db at just under 20hz at 350watts a piece, 1400watts total. I could feed these 600 watts each, but the excursion starts to become an issue under 20hz.

Why have you put a high pass on the plot? Where did you put it and how much? Obviously I would do that with the iNuke, but I would base that off what the excursion is plotting like.
If you want to lose 4 dB across the majority of the bass range for a 6dB increase over a 10 hz range then go with the 15 hz tune. 4 of these driver is a lot of bass either way. Yes in boxes this size 600 watts is way too much. The high pass is just a 2nd order at the tune
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post #13 of 16 Old 10-05-2016, 08:52 AM
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I have 4 of the pa-460's in 24hz tuned, 5ft^3 boxes and they are incredible (I've tried 18hz/20hz/24hz/28hz before settling on 24hz). In fact, I demo'd my 8 x ported 18" system (my other subs are 10ft^3/17hz with HST-18's) to @Bassment and another avs'er 2 weeks ago using the AVS 5star movie clips. Off the bat, the bass was very impressive - especially the midbass. Then in some scenes I was very familiar with, I noticed I wasn't feeling the weight of the ULF. And sure enough, the amp for the 4 x HST18's were off! The entire time, we were only experiencing 25hz+ content and the 3 of us thought the bass levels were already insane.

What I'm trying to say is, it's not worthwhile chasing the sub 20hz content, especially using these low xmax drivers. The output you're giving up to chase the 15hz tune is definitely not worth it from my direct experience playing around with the different tunes.
Of course, you won't know until you try it yourself. If I were you, I would design a slot port with multiple channels where it'll give you the ability to change the tuning by plugging/blocking the port(s).
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Honestly, Javs, I think your Faital-powered VBSS seems pretty well thought out. If you get good room gain the low tuning could work out very well for you. Depending on how you build the box, you could plan for adjusting the length of the port and tube to taste.

Ballpark starting point for an HPF would be second order at the same frequency as the sub's tuning frequency. Set the power you expect to have in the model, apply the filter, and see what excursion looks like. You'd want to keep it somewhere between Xmax and Xmech.


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post #15 of 16 Old 10-05-2016, 05:36 PM - Thread Starter
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Quote:
Originally Posted by lz7j View Post
I have 4 of the pa-460's in 24hz tuned, 5ft^3 boxes and they are incredible (I've tried 18hz/20hz/24hz/28hz before settling on 24hz). In fact, I demo'd my 8 x ported 18" system (my other subs are 10ft^3/17hz with HST-18's) to @Bassment and another avs'er 2 weeks ago using the AVS 5star movie clips. Off the bat, the bass was very impressive - especially the midbass. Then in some scenes I was very familiar with, I noticed I wasn't feeling the weight of the ULF. And sure enough, the amp for the 4 x HST18's were off! The entire time, we were only experiencing 25hz+ content and the 3 of us thought the bass levels were already insane.

What I'm trying to say is, it's not worthwhile chasing the sub 20hz content, especially using these low xmax drivers. The output you're giving up to chase the 15hz tune is definitely not worth it from my direct experience playing around with the different tunes.
Of course, you won't know until you try it yourself. If I were you, I would design a slot port with multiple channels where it'll give you the ability to change the tuning by plugging/blocking the port(s).
Quote:
Originally Posted by rhodesj View Post
Honestly, Javs, I think your Faital-powered VBSS seems pretty well thought out. If you get good room gain the low tuning could work out very well for you. Depending on how you build the box, you could plan for adjusting the length of the port and tube to taste.

Ballpark starting point for an HPF would be second order at the same frequency as the sub's tuning frequency. Set the power you expect to have in the model, apply the filter, and see what excursion looks like. You'd want to keep it somewhere between Xmax and Xmech.

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Cheers guys,

Yeah, I think I will just create an extra channel in the port so I can plug it and switch between maybe 17/18hz and 22hz or so. Hopefully room gain has a bit of effect too, but if I could I would like to not have to rely on it.

Seems like its a go for me. Keep y'all updated as I progress, will make this the build thread when I get on with it.

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