Dayton PA-460 18" Bass Reflex Design.

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damuffin

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I have just purchased two PA-460 18" Woofers. The dealer has a sale on these for $90 till the 31st and theres a Coupon for $5 off.
Dayton Audio PA460-8 18" Pro Woofer

I was thinking of building a box 36" tall with roughly 6.5cu Ft. Working out to around 18x18x36.

The lowpass filter will be at 250hz, and I will be using 3-5" drivers to cover the midrange on a Unity horn.

What Frequency should I tune the box to?
Should I use two 4" ports or build a vent across the bottom?


Thiele-Small Parameters
Resonant Frequency (Fs)28.3 Hz
DC Resistance (Re)5.6 ohms
Voice Coil Inductance (Le)3.9 mH
Mechanical Q (Qms)11.2
Electromagnetic Q (Qes)0.34
Total Q (Qts)0.33
Compliance Equivalent Volume (Vas)14.19 ft.³
Mechanical Compliance of Suspension (Cms)0.19 mm/N
BL Product (BL)22.3 Tm
Diaphragm Mass Inc. Airload (Mms)171g
Maximum Linear Excursion (Xmax)6 mm
Surface Area of Cone (Sd)1241.1 cm²
 
It sounds really good. I don't find it lacking anything except for DEEP drops on dubstep. Deadmau5, Daft Punk, etc. all sound good. Most all the pop music quits at 40 Hz anyway. I posted a thread on TechTalk about spectral content of various genres that you might want to look at.

Marc
 
What would be the lowest tuned frequency that won't add distortion. SPL is not my priority, I am looking for a broad and flat response.
 
damuffin said:
What would be the lowest tuned frequency that won't add distortion. SPL is not my priority, I am looking for a broad and flat response.
Click to expand...

What does it say on the Dayton Audio spec sheet ?

Optimum Cabinet Size (determined using BassBox 6 Pro High Fidelity suggestion)

Sealed Volume2.73 ft.³Sealed F3=72 Hz
Vented Volume5.68 ft.³Vented F3=47 Hz

You can also scroll down to the users reports section of the product page and see what others have done.
The first on the list speaks of an 11.5ft^3 ported box tuned to 37 hertz.

http://www.parts-express.com/dayton...9111X1517312X072d46d78a9823e050f7771de9bf3dc0
 
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6.5 cubic feet each or for both of them?
Typical design formulas would suggest (for one woofer) anything from ~7 to 9 cubic feet tuned to 34 or 32Hz respectively. A pair of 4" ports or a slot of equivalent area should be enough for this woofer.

That woofer looks like it might be a good candidate for a 6th order design with an auxiliary filter, which would get your box size down and give you deeper bass, at the expense of building the boost circuit. It all depends on what you are using it for...
 
Ron E said:
6.5 cubic feet each or for both of them?
Typical design formulas would suggest (for one woofer) anything from ~7 to 9 cubic feet tuned to 34 or 32Hz respectively. A pair of 4" ports or a slot of equivalent area should be enough for this woofer.

That woofer looks like it might be a good candidate for a 6th order design with an auxiliary filter, which would get your box size down and give you deeper bass, at the expense of building the boost circuit. It all depends on what you are using it for...
Click to expand...

I was thinking a ppsl to lower F3, but YES going with a 6th order assist would make a ppsl even nicer !!
 
I like the idea of 7 cubic feet per driver tuned to 32Hz, what is the port spec?
6th order would be really fun but it does have it's problems. With extension up to 250hz
there is going to be some ringing and fitting it in a 36"x18"x18-22" size may prove to be difficult.
I also thought about a folded horn but am worried about it dropping off at 200.
http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design.html
Any thoughts or Ideas are welcome. I am trying to learn a little here and have fun. 🙂
Thanks for your help
 
I should also mention that I'm using them in my living room 15'x18' sitting 10' away and hardly ever exceed 100db, so the X-max of 6mm isn't a concern. Theres a video showing a PA-460 producing a 11Hz tone with some big power and It didn't bottom. I also use active crossovers so there will be no EQ or DSP applied, but I still have the option of using a Linkwitz Transform altho room gain alone might be sufficient.

http://www.parts-express.com/dayton-audio-pa460-8-18-pro-woofer--295-036
 
damuffin said:
I like the idea of 7 cubic feet per driver tuned to 32Hz, what is the port spec?
6th order would be really fun but it does have it's problems. With extension up to 250hz
there is going to be some ringing and fitting it in a 36"x18"x18-22" size may prove to be difficult.
I also thought about a folded horn but am worried about it dropping off at 200.
http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design.html
Any thoughts or Ideas are welcome. I am trying to learn a little here and have fun. 🙂
Thanks for your help
Click to expand...
Optimum Cabinet Size (determined using BassBox 6 Pro High Fidelity suggestion)

Sealed Volume2.73 ft.³Sealed F3=72 Hz
Vented Volume5.68 ft.³Vented F3=47 Hz
Scott L
Click to expand...
The vented enclosure it's a high Q with +3.5dB's
OP doesn't mention details about his preferences, if that or a lower tunning and flattish speaker. Anyway. 😎

For practical/building and simulation references.
A reflex enclosure that's about 7cf. (never-> it has to small the external dimensions for that, it's more like 6cf)
Wood Thickness (3/4?)
Let's test: Enclosure 36"x18"x22", driver displacement 6.5 liter (18") and wood thickness, bracing about 0.35 cf (5% vol) you have 6.52 cubic feet. Then you need the ports and correct for alignment. A single 6" port (~0.16 cubic feet or 4.5 L each) or make use of double (2x) 4" ports (3.5L both it depends on the final tuning/length.)
Speaker Port Tubes in the Speaker Components Department at Parts Express | 320

Enclosure 36"x18"x22", Wood thickness 3/4" - 191.23L= 6.75ft³ (no battens)
Enclosure 36"x18"x22", Wood thickness 1" - 178.29L= 6.30ft³ (no battens)
Look at this design for reference http://www.diyaudio.com/forums/subw...t-ported-enclosure-15-driver.html#post4561257

A 172.0 L tuned to 35.0 Hz will give an alignment lifted about only 1dB (centered @60Hz) that might be or not of OP preference.
Now that we have Total Volume of Speaker (external dimensions above) we will have adequate alignment to calculate the right length for ports: 6.0cf/170L 😱

A VB = 170.0 L, FB = 32.0 Hz alignment will have 0.5dB lifting.

It's up to you to have this same volume and tuning after calibrating for your dimensions and alignment of your choice.
Wood thickness 3/4"
Driver displac. 18 inch - 6.5 liters
Bracing about 10L= 0.35ft³ or 5%
Considering (2x) Ports 4" Flared link
Ports 3.5L= 0.12ft³ being 2x ports of 4" diameter and 8" length (32.0 Hz.)
Battens 3/4"
170L= 6.00ft³ 😀

If I would use an adequate enclosure, yes or no, about 225L= 8.0ft³ inter. vol. net (it might be of interest to have +2dB's@30Hz or not because of the larger volume and weight of the extra wood)) to let the driver breath. Notice that this is not the same version as the old stock with different parameters not measured, when simulating old versions by mistake. Call it a new v2015 version if you want, that's what I did for reference.
 

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Inductor, thanks for your help bringing all my concerns to light. Now Ill just bust out the saw and get chopping.😎

Would it be worthwhile to bump it up to 36x19x22 internally?

What size of slot could I use at the bottom across the full width?
 
I would say yes to the extra int. volume if you don't move it around. For PA's you want to make them compact. In the case of a multi-way you have a more round of a response in LF. It's not a dilemma since it"s not a subwoofer. In this case (3-way) you might need the extra Q from a small speaker and high tuning.
 
Ron E said:
That woofer looks like it might be a good candidate for a 6th order design with an auxiliary filter...
Click to expand...

One of many possible 6th order vented box alignments for one woofer would be:
Vb=6.34 cubic feet
Fb=F3=Fboost=27Hz
Needs a second order highpass (Fboost) at 27Hz with a Q of 1.93 (a lift of 6dB). Many plate amps come with an adjustable (sometimes needs a little soldering) boost circuit which might suit.

Your ~37Hz tuned box has good output and >200W power handling above tuning but little below 40Hz. Probably deep enough for most popular music. You might want to use a subsonic filter if you listen to music with loud very low frequencies, as excursion limited power handling drops to about 50W at 24Hz and only 10W at 10Hz.
 
I think I'll answer some of the questions that many have asked

Hi all (and Mike too!).

I know the original poster very well and (perhaps) can enlighten those who have asked some questions that he may not have answered. So hopefully this provides a little more information for those needing it. Oh, he likes small scale rock, jazz, blues, vocals and some orchestral classics.

Firstly, I've known Mike for a few years now (10 maybe Mike?) and I think I started him along this long slippery slope of all things audio. We've done some great projects together, all of them have ended in well thought out (hopefully I helped here) and well built projects (due to Mike's capabilities). We mainly did loudspeakers. He's also moved on to digital and has had good success with building DACs and amplifiers. He moved away 4 or 5 years ago and we see each other a couple (or maybe upto 4) times a year.

He's grown into quite a mature listener and the deepest bass is not necessary, but low distortion bass is. His Unity horns are his latest acquisition and seem to be one of his best. I think what he wants is a sub/woofer/mid-bass capable of going cleanly to 250 Hz or so. If he can get to an honest high 30Hz-low 40 Hz range I know he would be happy. As he's stated, SPL is is not the goal, but high dynamic range is important to him. Thus he is using efficient drivers to more easily match the highly efficient mid/tweeter horns. Amplifiers are not a concern as he has multiple good amplifiers: SS, class D, Gainclones (-ish? Help me out here Mike.) and someplace a couple of good tube amps. He has a custom Marchand active crossover as well as a pair of subs that can go quite deep (mid to high 20Hz range IIRC) so he is pretty well equipped to drive pretty much anything to his desired (<100dB max) listening level. So no help needed regarding passive crossovers, or questions about amplifiers, etc. Some comments regarding the slopes of the crossover points would be helpful though.

He currently has a set of modified Klipsch CL-3 floor standers. I think the existing boxes are near 6 ft³ and he doesn't want to go (much) bigger. Bracing has been added, as well as suitable stuffing. A friend, Moray James (from right here on diyAudio.com) has helped Mike along modifying the CFs (of course from over 800 miles away). The 18" x 18 1/2" x 31" should get him close (the footprint might be a little larger than the CF-3s, but not by too much. He has been listening to the CF-3 woofer sections with the Unity horns and seems to like them plenty enough.

I think that pretty much sums up his listening preferences, listening levels. He has stated his listening room as:
damuffin said:
I should also mention that I'm using them in my living room 15'x18' sitting 10' away and hardly ever exceed 100db, so the X-max of 6mm isn't a concern.
Click to expand...

This should pretty much provide as much information as needed to help Mike make a reasonable choice regarding design. I actually lobbied against 18" drivers, preferring 15" or 12" as their Mm is much lower...
 
Vent location

After spending a few days pondering over the vent-port, I was thinking about making it 2"x18"x18" in 6.5' CF @ 31Hz and wanted to make the port surface rather large to cause more friction to help control the excursion of the driver. If it exits downward at the back of the enclosure this would allow some variation to the driver as the height was adjusted, or am I crazy? 🙄
 
Does anyone see a problem tuning the box to 23hz? I realise that I will be pushing the limits of the excursion, but if I used a high pass filter near 70hz I could correct some room gain and get lower frequency extension.
 
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