Triple driver - sealed. Pros/cons, and is it too much for a newbie

[turbodawg]

I was doing some measuring...
I can likely manage a pair of 27"x27"x27" sealed cabinets. That is about 11.3 cu.ft. external volume, and likely closer to 10 cu.ft. internally after bracing and driver displacement.

How would a sealed cab that size measure out with the Dayton Audio RSS460HO-4 18" Reference HO Subwoofer 4 ohm. Specs:
Power handling: 900 watts RMS/1,800 watts max • VCdia: 3" • Le: 2.10 • Impedance: 4 ohms • Re: 3.41 ohms • Frequency range: 20-500 Hz • Fs: 19.6 Hz • Sensitivity: 89.2 dB 1W/1m • Vas: 10.52 cu. ft. • Qms: 3.90 • Qes: 0.43 • Qts: 0.39 • Xmax: 12.75 mm • Dimensions: Overall diameter: 18.17", Cutout diameter: 16.69", Depth: 8.94"
http://www.daytonaudio.com/media/resources/RSS460HO-4 - Spec Sheet.pdf

Thanks Oliver, for your link to the post by mRgSr: http://www.diyaudio.com/forums/subwoofers/221660-new-ht-subwoofer-dayton-ref-18-a.html.
He just finished his, and I would love to hear his results/measurements. His internal volume was about 8 cu.ft. Loved the cabinet.

If the consensus is that it might measure well, and he is happy with his, this might well be worth a shot.

Any thoughts?

Two of these drivers =$500. inuke6000DSP 450+tax. Throw in the cabinet costs, I am pushing probably close to $1200-1300. But for two 18" subs, I think it is safe to say, I will likely not be able to pick up anything retail for under $2000 that outperforms this pair, correct? Please agree with me.... please?

What other amp/dsp options should I be considering. I know there is probably a good used market out there, but due to my ignorance in the matter, I probably will not have clue what I am buying, and should likely stick to retail for something that you guys recommend. Also, it is worth getting the DSP amp, or separate amp and dsp units, eg. minidsp.

If you can do 10 cubes each, you might want to model up some ported designs and see where that gets you. It also might allow you to step down to a nu3000dsp - more efficent, less mechanical power handling. With a low tune and properly designed ports, they will sound just as good as a sealed sub with EQ.

 

[Moonfly]

175 litres are certainly more desirable than 270 for spouse acceptance factor!!
On review of the specs, it does seem that the Fi is more sensitive and with a lighter Mms than the Dayton. Wouldn't know if they are equally stiff.
The Qts is little lower on the Dayton.
The resonant frequency is pretty high on the Fi with a Fs 32.1 vs 19.6 on the Dayton.

I am trying to make sense of these numbers - so I don't over think it, what might these numbers mean to me and for cabinet construction and sound.

Fs is one of things that goes against the driver a bit, but dont be fooled into thinking that a drivers Fs is a brick wall, they can and do play well below Fs with the right cab and proper eq. The suspension on them is a little stiffer than some other drivers, but it helps give the driver some good control and with that big motor on there it still goes plenty low. The Dayton is a good driver, but you only have to compare the Vd of the two drivers to see the difference between the two in how much air they can shift, and the ability to shift air is important if you want to go low. FWIW, I only use xmax figures as well, not xmech, so the spl output figures I quoted earlier are with the driver using full power in a cab designed to ensure the driver never exceeds xmax with that rated amount of power. That helps keep the system clean.

 

[Moonfly]

If you can do 10 cubes each, you might want to model up some ported designs and see where that gets you. It also might allow you to step down to a nu3000dsp - more efficent, less mechanical power handling. With a low tune and properly designed ports, they will sound just as good as a sealed sub with EQ.

Dont forget you dont have the same control over system Q with a ported sub, and you cant replicate a true linkwitz crossover with a ported sub either, which is the only way a sub can perfectly be in phase with the speakers (hence why sealed subs are noted to integrate better).

 

[weltersys]

Have you ever run a 15hz tone through a sub, and increased output till you can actually hear it measured with a spl meter. I can hear 20hz at fairly high levels, but 15hz and under is pretty nothing audible to me at all.

Yes, I have.
Built a tall isobaricly loaded tapped horn "Totem" sub for my shop, it rolls off below 20 Hz but corner loaded still puts out level clearly audible (around 80 dB) as low as 15 Hz without distorting.
I mostly listen to the radio in the shop, very few songs make the Totem sub come alive, the other 3 higher tuned subs are what generally fill the bill.

Much easier to hear clean low stuff using headphones, it takes a big cabinet or a lot of power to make much output below 20Hz.

 

[weltersys]

Dont forget you dont have the same control over system Q with a ported sub, and you cant replicate a true linkwitz crossover with a ported sub either, which is the only way a sub can perfectly be in phase with the speakers (hence why sealed subs are noted to integrate better).

Being "in phase" with the top cabinets is critical at the crossover point.
The phase response of the top cabinets must be determined to match the subs phase response at the acoustic crossover point, a ported top will require a different delay compensation than a sealed top cabinet.

With DSP, proper integration can be achieved with sealed, ported, or horn loaded subs.
All types of subs can integrate well, though certain designs require more DSP to integrate properly.

 

[Moonfly]

Being "in phase" with the top cabinets is critical at the crossover point.
The phase response of the top cabinets must be determined to match the subs phase response at the acoustic crossover point, a ported top will require a different delay compensation than a sealed top cabinet.

With DSP, proper integration can be achieved with sealed, ported, or horn loaded subs.
All types of subs can integrate well, though certain designs require more DSP to integrate properly.

The speakers do matter, but only in a system where the sub and speakers are sealed and a .707 system Q is used, and both crossover at 80hz and use LRC's will both be perfectly in phase. Any deviation from that and perfection isnt possible. The problem with ported subs is the driver and port each have their own phase, so its impossible to dial both in perfectly. The LRC research stuff shows us this.

 

[Moonfly]

Yes, I have.
Built a tall isobaricly loaded tapped horn "Totem" sub for my shop, it rolls off below 20 Hz but corner loaded still puts out level clearly audible (around 80 dB) as low as 15 Hz without distorting.
I mostly listen to the radio in the shop, very few songs make the Totem sub come alive, the other 3 higher tuned subs are what generally fill the bill.

Much easier to hear clean low stuff using headphones, it takes a big cabinet or a lot of power to make much output below 20Hz.

Sorry but I'm still not convinced. Besides the fact your chosen weapon is heavily rolling of below 20hz, I wouldnt trust a resonator to deliver a completely pure tone. Try it with a high end sealed sub using a 15hz sine wave at 100db, and I'd be quite surprised if you could still hear that. Maybe you can, maybe you cant, I just find it a bit far fetched. No offence intended, JMO.

 

[weltersys]

Sorry but I'm still not convinced. Besides the fact your chosen weapon is heavily rolling of below 20hz, I wouldnt trust a resonator to deliver a completely pure tone. Try it with a high end sealed sub using a 15hz sine wave at 100db, and I'd be quite surprised if you could still hear that. Maybe you can, maybe you cant, I just find it a bit far fetched. No offence intended, JMO.

Moonfly,

Headphones are a "high end sealed sub", it takes far less than 100 dB for me to hear a 15 Hz tone on my Sony MD 7506, or GK Ultraphones, which also use the 7506 element in Peltor muffs.
The revised curves of ISO 226:2003 indicate average persons can hear 16 Hz at 90 dB, I may be above that average, but even if not, 10 dB is an order of magnitude over what an average person needs to hear 15-16 Hz.

I felt ill after listening to a pair of BC18SW115-4 open air playing sine waves at 12-20 Hz during break in, though quite audible, I doubt they were at 100 dB.

Regarding your statement "The problem with ported subs is the driver and port each have their own phase, so its impossible to dial both in perfectly" it does not address the fact that the phase response of of (almost) any two cabinets can be combined, using time delay, to coincide at the crossover point.

There are no real world transducers with flat phase response over their entire frequency range, no "phase perfect" speaker exists without DSP.

To illustrate, the screen shot below has the magnitude and phase response of four tests:
An Acoustic Research sealed 10" (presumably a Q of .707)
A BC18SW115-4 in a bass reflex cabinet
A BC18SW115-4 in a tapped horn
A BC18SW115-4 in a tapped horn with top cabinets using sealed Eminence Alpha 8", crossed over and equalized for flat response.

The last is a giveaway, as only one trace has a flat response, which also equates to a smoother phase response.

Can you identify the crossover point between the TH 18" and the sealed 8"?
Can you identify the other three phase traces?

Have fun, good luck!

Art

 

[weltersys]

Besides the fact your chosen weapon is heavily rolling of below 20hz...

The Totem ISOTH sub in a corner had even more extended LF than I remembered, only about 5 dB down at 16 Hz.
Pretty darn good LF for a pair of $5 drivers .

Edit: The RTA 420 mic used for the measurement rolls off in response at least 2 dB at 16 Hz, 16Hz may be the 3 dB down point for the Totem sub.

Art

 

[Moonfly]

Moonfly,

Headphones are a "high end sealed sub", it takes far less than 100 dB for me to hear a 15 Hz tone on my Sony MD 7506, or GK Ultraphones, which also use the 7506 element in Peltor muffs.
The revised curves of ISO 226:2003 indicate average persons can hear 16 Hz at 90 dB, I may be above that average, but even if not, 10 dB is an order of magnitude over what an average person needs to hear 15-16 Hz.

I have to admit that I can also hear low 15hz tones from my headphones, but I do question why when with a sub I cant untill the level is pretty high.

Regarding your statement "The problem with ported subs is the driver and port each have their own phase, so its impossible to dial both in perfectly" it does not address the fact that the phase response of of (almost) any two cabinets can be combined, using time delay, to coincide at the crossover point.

The LRC is perfectly in phase at the crossover point providing all required parameters are met. The problem with a driver in a ported cabinet is that you have two sources of sound, but they are tied to the same cabinet, you cant separate them to dial them in so to speak. The difference in phase between the driver and port is locked in by the fact they share the same cabinet.

There are no real world transducers with flat phase response over their entire frequency range, no "phase perfect" speaker exists without DSP.

Agreed.

As a guess, I'd guess at the yellow.

 

[MedPed]

Tried playing with WinISD for the first time.

Cool stuff. I hope I am entering information correctly for new drivers.
Just to make sure I am doing things correctly, can someone just confirm two calculations.
1. For the Dayton RSS460HO-4 18"
Sealed cab volume 130.3 litres to achieve Qtc of 0.71.
2. For the Fi q18D2
Sealed cab volume of 109.9 liters to achieve Qtc of 0.71.
Does these numbers sound right?

You are guys are right about the ported though, can get very flat response down to 20 hz without any need for eq based on the sims, but I am worried about phase etc, and this being my first attempt, maybe sealed would be easier.

BTW, how does filling/insulation affect the cabinet. Does the WinISD sim assume a bare braced cabinet, or stuffed - and if so, with what?

The Fi is more expensive. Can get two Daytons within my budget - now expanded budget.

 

[weltersys]

I have to admit that I can also hear low 15hz tones from my headphones, but I do question why when with a sub I cant untill the level is pretty high.

The LRC is perfectly in phase at the crossover point providing all required parameters are met.

As a guess, I'd guess at the yellow.

There were three "guesses", the yellow is the tapped horn, which has a flatter phase response in the pass band than either the sealed or ported sub.

As you can see, the equalized TH is perfectly in phase with the delayed sealed top cabinets at the crossover point, you can still guess at the crossover frequency if you would like.

Furthermore, the ported cabinet can be matched to a sealed or ported top cabinet, as can the sealed cabinet.

Not sure what you mean by "LRC", but there are certainly many ways to achieve an integrated phase response at the crossover point, I'll take your word that "LRC" is one of them.
IIRC, the TH used a LR24 filter, while the sealed top cabinets use a BW24 to achieve the smooth phase response.

Headphones that can produce decent levels at 15 Hz must be closed, and therefore attenuate outside noise by some degree, making it easier to hear the LF tone.
Perhaps you should measure the SPL at 15 Hz required for you to hear your sub, likely it is around 90 dB SPL in a quiet environment.
However, 90 dB at 15 Hz only sounds about as loud as 25-30 dB at 1000 Hz, and unless you live in a dead quiet house, the ambient noise level may be above that, requiring a louder level.

Art

 

[Moonfly]

Tried playing with WinISD for the first time.

Cool stuff. I hope I am entering information correctly for new drivers.
Just to make sure I am doing things correctly, can someone just confirm two calculations.
1. For the Dayton RSS460HO-4 18"
Sealed cab volume 130.3 litres to achieve Qtc of 0.71.
2. For the Fi q18D2
Sealed cab volume of 109.9 liters to achieve Qtc of 0.71.
Does these numbers sound right?

You are guys are right about the ported though, can get very flat response down to 20 hz without any need for eq based on the sims, but I am worried about phase etc, and this being my first attempt, maybe sealed would be easier.

BTW, how does filling/insulation affect the cabinet. Does the WinISD sim assume a bare braced cabinet, or stuffed - and if so, with what?

The Fi is more expensive. Can get two Daytons within my budget - now expanded budget.

You ideally want a sealed system to have a .5-.7 system Q. As such I always aim for somewhere in between, about .6 to .65. Q will raise slightly once room gain augments the subs natural response as well so thats another reason I like to aim a bit lower. Again, when you run dual sub, Q will again alter a touch. Dont forget that eq will also affect things like that. Personally, I think the Fi would work best in 150 litres as a minimum, otherwise it may sound a little boomy and probably sacrifice a little low end as well.

I dont have a driver file for the Dayton, if I get time I'll plug in the numbers later and have a look.

Stuffing helps make the sub sound deeper without the need to make the cabinet larger to achieve the same thing. It can also help dampen any resonances inside the cab.

 

[Moonfly]

There were three "guesses", the yellow is the tapped horn, which has a flatter phase response in the pass band than either the sealed or ported sub.

As you can see, the equalized TH is perfectly in phase with the delayed sealed top cabinets at the crossover point, you can still guess at the crossover frequency if you would like.

Furthermore, the ported cabinet can be matched to a sealed or ported top cabinet, as can the sealed cabinet.

Not sure what you mean by "LRC", but there are certainly many ways to achieve an integrated phase response at the crossover point, I'll take your word that "LRC" is one of them.
IIRC, the TH used a LR24 filter, while the sealed top cabinets use a BW24 to achieve the smooth phase response.

Headphones that can produce decent levels at 15 Hz must be closed, and therefore attenuate outside noise by some degree, making it easier to hear the LF tone.
Perhaps you should measure the SPL at 15 Hz required for you to hear your sub, likely it is around 90 dB SPL in a quiet environment.
However, 90 dB at 15 Hz only sounds about as loud as 25-30 dB at 1000 Hz, and unless you live in a dead quiet house, the ambient noise level may be above that, requiring a louder level.

Art

The guess was for the ported/sealed combination. It was an off the cuff guess based on the slightly more peaky looking response of the yellow trace at higher frequencies. Its not always that easy to identify subs off graphs once eq is applied, you need things like impulse response measurements etc, time based measurements are important. An LRC is a Linkwitz Reilly Crossover.

I sold all my AV about a year ago due to moving country, and the recession has prevented its replacement, so I cant currently do any testing of my own unfortunately.

 

[turbodawg]

You are guys are right about the ported though, can get very flat response down to 20 hz without any need for eq based on the sims, but I am worried about phase etc, and this being my first attempt, maybe sealed would be easier.

The group delay and phase response don't really matter much below about 60-80hz, everything you'll hear in room is going to have a bunch of reflections.

Are you going to cross this to your mains with 1st order filters, and time correct the mains to the subs? Because that will make a much bigger difference in perceived transient response, especially in the midbass.

You can model parametric EQ's and filters in winisd, and you'll see that these also have a major impact on phase and group delay.

Do not be afraid of ported boxes. When built well (stiff, damp box - internally coated plywood), with a proper sized flared port(s) and a low tune, they sound just as good as a sealed box and are more efficient. They key is to have a mildly sloping response that blends with your room but still gives you a bit of "house curve", and to EQ out any room nodes.

 

[MedPed]

Bugged that I wasn't able to play with WinISD before leaving from work today. I really have to get a windows installed on my macs at home. This sucks.
I really hadn't given the crossover or time correction any thought! I guess this is a good time.
My mains would be powered bookshelves with balanced XLR or single ended RCA inputs They are fairly flat till 40 Hz.
Not sure how to do this, or what I need. I believe the Inuke DSP amps have crossover functionality (and time correction?), but they only have a single pair of outputs, which will go to the sub, and no line level outputs for high pass. I guess I have to either 1) run the speakers in parallel, or 2)place a crossover after the signal leaves the preamp dividing the signal between the mains and the inuke.
The advantage of #1 is that I can dedicate a high pass crossover to the mains, and let the inuke take care of the sub (basically each unit has its own filter); the advantage of #2 is simple single crossover. Does that even make sense?
I have no idea how this may pan out - or what all this really entails. This is really giving me the newbie blues!
Any ideas of where to start?
Turbodawg, I think you are right. In the perfect listening room, the argument may be valid that sealed is truly better, but in real world, common living room, a well made ported is definitely more useful. I agree. I like the idea of efficiency, but I don't know why I am still skittish of getting the tuning right in a ported sub. I really feel like I don't know what I am doing, and the learning curve is so steep, I am scared that once built, if I don't like it, it will be the end of DIY form me.
I am hoping that with running stereo subs, with real inroom reflections, a sealed sub will not require too much Eq and a single stereo inuke 6000 will be ok. I am hoping...
But for project # 2... ported experiment for sure!

 

[MedPed]

Would miniDSP be worth the investment? approx $125 for the balanced version.
It would be line (low level).

 

[weltersys]

Would miniDSP be worth the investment? approx $125 for the balanced version.
It would be line (low level).

Most any DSP is worth the investment if you are serious about integration of the sub to the main speakers.

However, to properly integrate the subs to the mains, some measurement must be undertaken.

Most dismissals of various sub designs are due to lack of actual measurement, a requirement to achieve the best response.

 

[MedPed]

I think I have settled on the idea of two sealed subs, each with the 18" Dayton reference sub.

The more I have read, the more I realized, the importance of measuring and correct EQ - phase, timing, and the right amount of boost for my room - and know that I will need quality DSP. My DAC/preamp is awesome with >120dB S/N ratio, and I really want to try and preserve the quality at least until my amps/mains.
I am still very confused with what to power the subs with and how to DSP. I thought I was settled on the inuke6000DSP - until I kept reading...
The Behringers come in 5 "flavors". And I still can't seem to find what a significant difference in these amps - other than the obvious inukeDSP having the DSP.
iNuke - not considering.
INukeDSP - has DSP
Europower EP - best deal.
Europower EPQ - not considering.
Europower EPX - nice, but relatively expensive.
Does anyone have any experience for the above amps - their differences?
I was contemplating b/w iNuke 6000DSP for $450, vs the EP4000 for $280, along with a miniDSP for $125. That deal on the EP4000 is unbelievable - if the amp will serve the purpose that is. The Europower amps seem to have better power stats and damping than the iNukes. The EPX is relatively expensive (EPX 4800 is $400 - without DSP) and therefore was not on my "short list" - should it be?

There seems to be an advantage to me of using a miniDSP is that it will serve as a line level HPF for my mains as well, and I can phase/time adjust the subs/mains all in one place. The S/N for it isn't that hot though. I could simply run my mains full range, and crossover the sub even lower - about 40Hz if using the iNuke option - but that will be a waste to me as far as offloading the mains LF to the sub. I was hoping to crossover b/w 60-80.

What I didn't like about the iNuke DSP is that there is no HPF for the mains at line level.
Any other suggestions, thoughts? Could I just get a cheap passive line level HPF for the mains? How would I time/phase adjust the DSP in the iNuke if the mains are not connected to it? Maybe I don't quite understand how this all works.

I could go for the higher end miniDSP - but even with the great deal on the EP4000 I am pushing well above $1000 system cost - but will be forced to consider it if there is a consensus that it is necessary for my goals.

Secondly, regarding the cabinets, is there an advantage to work with certain woods, or can I just go to the local Curtis Lumbar, and pick up some nice looking wood and stains.

Thirdly, when ordering the subs, (and amps), what other hardware, should I get? If using >1" baffle, will the standard screws be good enough, or is there value in using bolts?

Lastly, if I am running dual subs in this configuration, what q should I be shooting for in WinISD to measure out the cabinet size. As suggested by Moonfly, I should keep it below 0.7 due to room, and dual sub influence (see post 93), but question if how low - 0.6?

Thanks for all your help so far.
I really want to place my order and get cracking on this!

 

[woof]

Late to the party, but this is my baby with 3 of the 12 ohm NHT 11-083 subs in a sealed enclosure.Introducing Towering Subferno