DIY Speaker Noob - Single 15" Ported Build for HT Use - AVS Forum
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post #1 of 10 Old 11-02-2012, 11:39 PM - Thread Starter
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Hello all,

I am thinking of upgrading my Onkyo HTIB sub with a DIY 15" woofer build. Budget is around $400 for driver and amp with a self-made box. My room is 19'4" x 15'6 x 8' and I'd say I do 90/10 HT/music. I've got a Onkyo TX-NR609 driving a Polk CS20 center and Polk Tsi400 towers for fronts with the HTIB speakers as surrounds right now (looking at getting some Tsi200s or FXI-A4's to upgrade there). Nothing fancy but much better than the HTIB speakers/receiver.

After scouring these forums (and immediately getting shot down by the wife when I proposed building a LilMike F-20) I think I've settled on a Dayton Audio 15" HO or HF driver with a 500W plate-amp (either Dayton Audio or Bash). I'm sure people will try to talk me into a iNuke amp or something along those lines with DSP, but for my use, I think this cost/performance will be a great upgrade from where I'm at now.

I think I've got the wherewithal and tools to do a ported cabinet build with the plate amp installed into the cabinet on the back. I would possibly like to do a down firing driver with the port on the front (or vice versa). I wouldn't be opposed to a front driver/front port build but I like the idea of having the driver hidden. Given the above info, I've got the following questions:

1) Given my room size and mainly HT use, would this driver and a ported box serve as a good upgrade? (not looking for audiophile SQ, just some decent bass when I watch movies and such upstairs)

2) Any thoughts on the choice between the HF/HO/Titanic sub from Dayton (or another around the same price)? The HO is much cheaper now and reportedly favors smaller cabs and provides good HT output.

3) Any big differences between the Dayton Audio and Bash amps? (as you can see, I've gravitate towards the selection on parts express)

4) Is 500W enough to get decent home theater bass without breaking the neighbor's windows? (or could I possibly squeeze by with the 300W Bash) Budget is a big consideration for the wife and I just want a good upgrade without wasting money on a retail Klipsch or something along those lines.

5) I've been doing some modeling with WinISD and am leaning towards a 5CF box tuned to 18Hz. Seems if I throw a true 500W at it in this configuration, I could risk exceeding Xmax, But in most situations I wouldn't risk damaging the driver above ~15Hz.

6) I just want to double-check that I am interpreting WinISD correctly: Larger box volume allows me to dig deeper into the low frequencies. On the other hand, a larger box also allows more excursion which risks damaging the driver. I need to find the "sweet spot" in box size that will allow flatter low freq performance without exceeding Xmax at expected power levels. Is this a good summary of the modeling?

7) When considering a down firing driver or port, does this have any real impact on the performance of the enclosure? Or will the system perform the same given the port diameter and length and the inner volume of the cabinet?

8) When building the cabinet, do I need to brace the back panel if it has a cut-out for the plate amp in it?

9) I need an exact value on how much happier that I'll be spending 400 dollars on this than I would on a retail box. Without this precise measurement, I won't be able to decide if this is right for me. wink.gif

Apologies if I've asked any questions that have been addressed ad nauseum in other parts of the forum. Thanks in advance for any advice or criticism of my approach and assumptions here. I'll try to keep up to date with any build or parts decisions I make but I can't promise anything as I'm finishing up grad school this semester. (and with my birthday and christmas coming up, the old lady frowns upon discretionary spending such as this).

Sorry for the extensive post and thanks again for all the help!
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post #2 of 10 Old 11-04-2012, 10:19 AM
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Hey Fleek, It sounds like we have similar projects in our near future. I just finished remodeling my basement and as soon as I get the carpet installed I'm moving my home theater down there. As part of that process I'm planning on building a Subwoofer. I'm considering multiple designs at the moment but one of them is a 15" ported based on the Dayton Reference HF. I'm very new to speaker design but I'll be happy to tell you what I (Think I) know. If I screw anything up I'll rely on others to set the record straight.
Quote:
Originally Posted by fleek1116 View Post

1) Given my room size and mainly HT use, would this driver and a ported box serve as a good upgrade? (not looking for audiophile SQ, just some decent bass when I watch movies and such upstairs)

I've been subjected to HTIB subs at friend's houses before. I do believe your proposed build would be an upgrade over most HTIB subs.

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Originally Posted by fleek1116 View Post

2) Any thoughts on the choice between the HF/HO/Titanic sub from Dayton (or another around the same price)? The HO is much cheaper now and reportedly favors smaller cabs and provides good HT output.

I decided on the HF over the HO as HF is "high fidelity" and I want mine for movies and music. HO is "high output" so it should be capable of being driven harder/louder. I've read up on both subs and people seem to be quite happy with both of them. I've not researched the Titanic at all.

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Originally Posted by fleek1116 View Post

4) Is 500W enough to get decent home theater bass without breaking the neighbor's windows? (or could I possibly squeeze by with the 300W Bash) Budget is a big consideration for the wife and I just want a good upgrade without wasting money on a retail Klipsch or something along those lines.

My motivation is the same as yours. I'd love to hear some opinions on this!

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Originally Posted by fleek1116 View Post

5) I've been doing some modeling with WinISD and am leaning towards a 5CF box tuned to 18Hz. Seems if I throw a true 500W at it in this configuration, I could risk exceeding Xmax, But in most situations I wouldn't risk damaging the driver above ~15Hz.

From what I gather it is ok to exceed Xmax by a little bit. The driver only risks damage if you exceed Xlim, the mechanical limit of the driver. Unfortunately most manufacturers do not publish Xlim. There are many "rules of thumb" about Xlim. Some say Xmax + 50%, some say +100%, I think +30% is probably a safe bet. Your plate amp will likely have a HPF (high pass filter) somewhere around 20 Hz to deal with this issue. The downside to this is that your output will be down 3 dB at 20 Hz because of this filter.

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Originally Posted by fleek1116 View Post

6) I just want to double-check that I am interpreting WinISD correctly: Larger box volume allows me to dig deeper into the low frequencies. On the other hand, a larger box also allows more excursion which risks damaging the driver. I need to find the "sweet spot" in box size that will allow flatter low freq performance without
exceeding Xmax at expected power levels. Is this a good summary of the modeling?

There is more to Win ISD & cabinet modeling than that. Other things to consider (not a complete list) are:

Port width/length - You'll probably want to design your port such that it fits within your box AND has some breathing room internally. Rule of thumb is, if you are using a 4" port, leave 4" of space clear around the openings. 6" clear for 6" ports. You get the idea smile.gif

Air speed within the port - If the air velocity within the port is too high you'll hear it, also known as port chuffing. You can learn more and download a program to help you with port calculations here: http://www.subwoofer-builder.com/flare-it.htm

Group delay / phase shift - I'm iffy on this one. A high group delay can have a detrimental affect on your sound quality, although I do not understand the details.

Muddy/Boomy bass - Again, not sure of this one, but from what I gather the larger the box the muddier/boomier the bass. This is the opposite of "tightness". Most people prefer tighter bass to boomy. I've read that if you stick close to the box size/tuning suggested by the SBB4 alignment (as modeled via WinISD) then you'll be ok.

Quote:
Originally Posted by fleek1116 View Post

7) When considering a down firing driver or port, does this have any real impact on the performance of the enclosure? Or will the system perform the same given the port diameter and length and the inner volume of the cabinet?

As long as the port has the proper room to breath as I mentioned above, I think the port will be fine anywhere.

The driver should only be used down firing if it passes the test given here: http://www.parts-express.com/resources/woofer-mount-up-down.cfm

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Originally Posted by fleek1116 View Post

8) When building the cabinet, do I need to brace the back panel if it has a cut-out for the plate amp in it?

Yes? Cannot see why a cutout would change the fact that bracing is needed to reduce cabinet vibration.
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Originally Posted by fleek1116 View Post

9) I need an exact value on how much happier that I'll be spending 400 dollars on this than I would on a retail box. Without this precise measurement, I won't be able to decide if this is right for me. wink.gif
Apologies if I've asked any questions that have been addressed ad nauseum in other parts of the forum. Thanks in advance for any advice or criticism of my approach and assumptions here. I'll try to keep up to date with any build or parts decisions I make but I can't promise anything as I'm finishing up grad school this semester. (and with my birthday and christmas coming up, the old lady frowns upon discretionary spending such as this).
Sorry for the extensive post and thanks again for all the help!

I too wonder about this smile.gif In particular, I'm eyeing the Klipsch RW-12d which routinely goes on sale for about $300.


Good questions, hope I've helped a little. I look forward to seeing what you end up doing.
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post #3 of 10 Old 11-04-2012, 11:49 AM
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Too bad you can't do an f-20 or a THT. The Tht comes in two different sizes too. You'd be able to use a Bash 300 and have much more output at the low price you have to spend. You could put a LP Tht behind a couch. Only problem is that your mains wouldn't be able to keep up.

Current HT: HTPC-->Epson 5010 projector-->135" screen, BFM TLAHs x7 & THT
Build log: DIY rotary sub for contemporary HT in 100 year old house?
Andreas' Slow Rotary Sub build
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post #4 of 10 Old 11-04-2012, 12:25 PM
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"After scouring these forums (and immediately getting shot down by the wife when I proposed building a LilMike F-20)"

big horns don't have to be ugly.

have you taken a look here?

http://www.avsforum.com/t/1404092/wanted-big-bass-big-room-open-to-an-even-bigger-room-with-lots-of-windows/90

if you go with a plate amp, they tend to have a 2nd order highpass around 18-20hz, so plop that in your models.

"9) I need an exact value on how much happier that I'll be spending 400 dollars on this than I would on a retail box. Without this precise measurement, I won't be able to decide if this is right for me."

get it loud first (>120db), then drive it deep. there are some tiny horns that are available in flat packs that can get you loud...

one of these in each corner will blow your htib sub out of the water:
http://www.diysoundgroup.com/flat-packs-1/subwoofer-flatpacks-1/anarchy-th.html

Listen. It's All Good.
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post #5 of 10 Old 11-05-2012, 01:51 PM - Thread Starter
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Quote:
Originally Posted by hernejj View Post

I've been subjected to HTIB subs at friend's houses before. I do believe your proposed build would be an upgrade over most HTIB subs.
I decided on the HF over the HO as HF is "high fidelity" and I want mine for movies and music. HO is "high output" so it should be capable of being driven harder/louder. I've read up on both subs and people seem to be quite happy with both of them. I've not researched the Titanic at all.
After refining my models a little bit, I think I'm with you and am going to do the HF. People seem to be incredibly happy with either of those and I haven't heard anyone arguing to spend the extra money on the Titanics.
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Originally Posted by hernejj View Post

There is more to Win ISD & cabinet modeling than that. Other things to consider (not a complete list) are:
Port width/length - You'll probably want to design your port such that it fits within your box AND has some breathing room internally. Rule of thumb is, if you are using a 4" port, leave 4" of space clear around the openings. 6" clear for 6" ports. You get the idea smile.gif
Air speed within the port - If the air velocity within the port is too high you'll hear it, also known as port chuffing. You can learn more and download a program to help you with port calculations here: http://www.subwoofer-builder.com/flare-it.htm
Group delay / phase shift - I'm iffy on this one. A high group delay can have a detrimental affect on your sound quality, although I do not understand the details.
Muddy/Boomy bass - Again, not sure of this one, but from what I gather the larger the box the muddier/boomier the bass. This is the opposite of "tightness". Most people prefer tighter bass to boomy. I've read that if you stick close to the box size/tuning suggested by the SBB4 alignment (as modeled via WinISD) then you'll be ok.
Haha, that was definitely a gross oversimplification of the WinISD capability but I was just making sure I was intrepreting those main plots correctly. Quite an easy to use and amazing tool for it's purpose. I certainly have learned an amazing amount about this stuff in the past few days by messing with that.

I think I'm going to do around a 10 ft^3 box with 2 3" x 15.75" long flared ports. That should tune it around 17Hz if I remember my WinISD numbers correctly from last night. That seemed to keep port air velocity low enough to avoid chuffing and keep me from having insanely long ports. Some posts on PE Tech Talk indicated the HF 15" liked being in a box that size and my plots seem to agree. (and a 10 ft^3 ported box is still a lot more agreeable for my wife than a 5ft tall horn).
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Originally Posted by hernejj View Post

As long as the port has the proper room to breath as I mentioned above, I think the port will be fine anywhere.
The driver should only be used down firing if it passes the test given here: http://www.parts-express.com/resources/woofer-mount-up-down.cfm
I think I'm going to ignore the down firing idea. I had no real reason to do so other than the cleaner look of no speaker grill on the front. Don't need to worry about sagging problems etc. with very little to gain.
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Originally Posted by hernejj View Post

Yes? Cannot see why a cutout would change the fact that bracing is needed to reduce cabinet vibration.
My original thought was that a cutout might bring the size of the material in the panel down below the "brace any panel 12x12 or larger" size. After actually looking at plate amp sizes, I think the panel would still be over 12x12. Either way, it would probably be safer to just brace the remaining panel.
Quote:
Originally Posted by hernejj View Post

I too wonder about this smile.gif In particular, I'm eyeing the Klipsch RW-12d which routinely goes on sale for about $300.
Good questions, hope I've helped a little. I look forward to seeing what you end up doing.
I'm hoping that a $170 driver plus a $200 amp with more power, coupled with a purposefully designed box will get me some performance gains. Plus being able to rattle your friends' glasses off and tell them "I built that" will always bring a little extra satisfaction.

Thanks for your input! Good luck on your build. This seems like a fun but addicting hobby to get into.
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post #6 of 10 Old 11-05-2012, 02:36 PM - Thread Starter
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Quote:
Originally Posted by hernejj View Post

big horns don't have to be ugly.
have you taken a look here?
http://www.avsforum.com/t/1404092/wanted-big-bass-big-room-open-to-an-even-bigger-room-with-lots-of-windows/90
Those horns built into the window bench are amazing! I think that's definitely something the wife would buy into. Unfortunately there's not really an opportunity for a design like that in our current room.

Quote:
Originally Posted by hernejj View Post

if you go with a plate amp, they tend to have a 2nd order highpass around 18-20hz, so plop that in your models.
In regard to the plate amp question: I think I've decided on 500W to give myself some extra headroom and avoid stressing the amp at lower levels. Choices I'm stuck on are the Dayton SPA500, OAudio BASH 500W and the Yung Class D 500W. Each seem to have some ups and downs. SPA500 has PEQ and a sealed back but some report power-on "pop" and poor auto-on performance. OAudio seem to have generally positive reviews but some reports of loose component problems along with a flimsy face that can cause vibrations. The Yungs have fewer reviews but most seem to be positive. There is conflicting info about the subsonic HPF and there is no EQ (aside from the 6dB@25Hz boost offered on one of the models which generally people say to avoid with a ported box). Any recommendations on the plates amps?


My waffling on the plate amp has brought me to a third option:

Amazon currently has the iNuke NU1000DSP for 254 + free shipping which is not much more than the other 500W plate amps.
http://www.amazon.com/Behringer-NU1000DSP-iNuke-Power-Amplifier/dp/B005EHIN3A

I could run this guy in bridged mode and get 1000W to my 4ohm driver. I also avoid the extra complexity/issues related to building a plate amp into the box and get the EQ features offered with the DSP models. I may be starting to lean this way even though it costs a bit more. Questions about this approach:
1) I should be ok with 1000W into this sub as long as I'm cognizant of the gain I set the amp to and the volume I put out of the receiver, correct?
2) Some people report the fan being quite loud on the NU1000DSP. Anyone have comments on this? Is this a reason to avoid?
3) If I ever end up building another sub of the same type (Dayton HF 15" in a ported box), will the 300W/channel @4ohms that the NU1000 provides when not bridged make them seem completely underpowered? Or will the additional driver make up the difference?
4) On the same note, if we move to a room more apt to horn enclosure integration, will 300W/channel drive these 15's appropriately? Based on what I've read, I think the answer if definitely yes.
5) In general, will SQ on this amp going to be noticeably better out of the box than the plate amps? (Obviously the EQ abilities will help me to dial it in once I have a chance to tweak)
6) Documentation indicates "line-level input" which seems to indicate I just use my LFE out correct? Do I just need an RCA-to-XLR adapter from my Sub pre-out?


Any general comments on paying the extra ~$40 dollars for the NU1000DSP would be greatly appreciated.
And are my LCRs going to be completely outmatched in this setup? Am I going to need to dial back to sub to avoid over powering the mains?

Off topic question: If I have to choose between upgrading my HTIB sub and the HTIB speakers I'm using as satellites, am I smart in choosing to upgrade the sub first?
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post #7 of 10 Old 11-08-2012, 05:10 AM
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As far as plate amps go, I have a Yung 300 watt plate amp that I purchased from Parts Express for a really good price. It drives my MFW-15 just fine. I ended up building a small square enclosure for the plate amp that I sit on top of the sub. It turned out really nice. I am getting ready to build some horn subs myself, trying to decide between LiLmikes F-20, a CSS TREO-12, or possibly a Krackin 212, which ever one I end up going with, I will use my Yung plate amp to power this bad boy.
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post #8 of 10 Old 11-08-2012, 05:33 AM
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Quote:
Originally Posted by fleek1116 View Post

1) I should be ok with 1000W into this sub as long as I'm cognizant of the gain I set the amp to and the volume I put out of the receiver, correct?
2) Some people report the fan being quite loud on the NU1000DSP. Anyone have comments on this? Is this a reason to avoid?
3) If I ever end up building another sub of the same type (Dayton HF 15" in a ported box), will the 300W/channel @4ohms that the NU1000 provides when not bridged make them seem completely underpowered? Or will the additional driver make up the difference?
4) On the same note, if we move to a room more apt to horn enclosure integration, will 300W/channel drive these 15's appropriately? Based on what I've read, I think the answer if definitely yes.
5) In general, will SQ on this amp going to be noticeably better out of the box than the plate amps? (Obviously the EQ abilities will help me to dial it in once I have a chance to tweak)
6) Documentation indicates "line-level input" which seems to indicate I just use my LFE out correct? Do I just need an RCA-to-XLR adapter from my Sub pre-out?
Any general comments on paying the extra ~$40 dollars for the NU1000DSP would be greatly appreciated.
And are my LCRs going to be completely outmatched in this setup? Am I going to need to dial back to sub to avoid over powering the mains?
Off topic question: If I have to choose between upgrading my HTIB sub and the HTIB speakers I'm using as satellites, am I smart in choosing to upgrade the sub first?

1 the iNuke 1000 is 1000w peak. Spec is 750 rms though I haven't seen any independent tests for the 1000.
2 the fan on my 3000 sounded like a vacuum cleaner. I replaced it with a $9 fan and added a $10 pack of heat sinks and a $3 rubber fan gasket. It's now totally silent.
3 Adding another driver will cause the amp to run at an overall 8 ohm load. You will go from 750w to 430w total gaining about 3 db from the extra driver and losing about 2db from the lower power, all things being equal.
All things are not equal though, so with lower distortion and power compression and not being excursion limited you will actually gain a little more output than 1db. It won't be a huge gain though, maybe 3-4db. If you plan to expand to 2 or more subs later you should go ahead and get the iNuke 3000. The iNuke doesn't have a line out so you need to buy as big as you are going to need because you can't send the eq'ed signal to another amp. If you are limited to the iNuke 1000 consider buying a driver that can make use of all 750w like the titanic (looks like I'm the first to argue for the titanic).
4 300 ea is yes. You don't have 300 each with the 1000. See above, it's actually 210 in 4ohm stereo.
5 The ability to eq is a huge advantage. The built in HPF is nice too. There are other options though like a mini dsp. Having a filler sub in the opposite corner of the room does more to flatten in-room response than eq also.
6 hossa makes an xlr to rca adapter for $5. Monoprice has xlr to rca cables and rca splitters if you want to split to run the inuke in stereo, though not necessary if you are bridging.

OT - how bad are your satellites?
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Originally Posted by fleek1116 View Post

10 ft^3 box with 2 3" x 15.75" long flared ports

Not enough port area. Go with a single 6" port. No, 3+3 does not equal 6.
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post #9 of 10 Old 11-08-2012, 09:31 AM - Thread Starter
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2 the fan on my 3000 sounded like a vacuum cleaner. I replaced it with a $9 fan and added a $10 pack of heat sinks and a $3 rubber fan gasket. It's now totally silent.
The fan mods seem pretty common if I go the iNuke route. I've got some 80mm PC case fans lying around so hopefully those would work.
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OT - how bad are your satellites?
They are the old fronts from my HTIB system from Onkyo (about 8yrs old). Dual ~3" woofers with a tweeter in the middle. They certainly don't 'wow' as surrounds. Maybe the smaller surrounds it came with would be better suited than the fronts for that duty. I thought the extra output might help but after doing some reading I'm not so sure. I was considering Polk Tsi100, Tsi200s (to stay timbre matched with my LCRs) or going to the FXI-A4 to stay with the same brand but higher performance. My thought would be to upgrade the sub first. But hopefully they'll both get done soon. Thoughts on the upgrade list?

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Not enough port area. Go with a single 6" port. No, 3+3 does not equal 6.
Is this a port noise/chuffing consideration? What is the typical air velocity one wants to stay below if listening from about 12 ft?
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post #10 of 10 Old 11-08-2012, 09:38 AM
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I would do the sub first. I notice my sub more than I would ever want to notice my surrounds. 3" mids and a tweeter isn't so bad.

I've refered to this page for years for port calcs:
http://www.carstereo.com/help/Articles.cfm?id=31

It will give you a minimum port area based on driver size, excursion and frequency. Also, the slot port calculator on this page is much more accurate than trying to use WinISD's square port, should you go that route.
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