DIY sub

[flippo]

Still planning to make my sub. I am looking at a rythmik 12" servo subwoofer kit as an alternative to the Dayton driver and amp. Is there an advantage to a servo sub?

 

[WmAx]

Is there an advantage to a servo sub?

Yes, in theory. In reality? Yes, but only with substantial effect if the driver at question was not very linear. A very high grade driver really has no need for servo.

-Chris

 

[TLS Guy]

Servo

Which Rhythmic sub were you planning to build, the sealed or vented? A servo system makes a little more sense sealed, however it is just one method to EQ the bass. The sealed sub has very good LF extension for a small sub. However the driver reaches xmax at 75 db, so it will not be the most powerful sub in the world. This just shows there is no free lunch for any Eq system.

If it is clean accurate bass you are after rather than quantity it could be a good choice.

 

[WmAx]

Still planning to make my sub. I am looking at a rythmik 12" servo subwoofer kit as an alternative to the Dayton driver and amp. Is there an advantage to a servo sub?

You know, there is 1st rate quality subwoofer driver that is not too expensive, that can be adapted to just bout any situation: Infinity Kappa Perfect VQ12 (single VC version). With it's combination of extraordinary linear motor and it's unique adjustable motor Q/Bl, you can get optimal results in just about any situation required, without compromise of sound quality or SPL. Why don't you compare the options?

-Chris

 

[TLS Guy]

Good one

Chris seems to have come up with a good one for you with that driver.

Here is the best alignment I could get. It seems more promising vented than sealed, unless you want to use a lot of EQ. Here is the alignment.


Name: Kappa Perfect12.1
Type: Standard one-way driver
Company: Infinity Systems Inc.
Comment: Kappa Perfect series
No. of Drivers = 1
Fs = 23.32 Hz
Qms = 10.28
Vas = 83.28 liters
Cms = 0.208 mm/N
Mms = 224 g
Xmax = 14.15 mm
Sd = 531 sq.cm
Qes = 0.46
Re = 4 ohms
Le = 3.05 mH
Z = 4 ohms
BL = 16.9 Tm
Pe = 350 watts
Qts = 0.44
2.83-V SPL = 96 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square (optimum)
Vb = 4.849 cu.ft
Fb = 18.15 Hz
QL = 6.164
F3 = 19.03 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 4 in
Lv = 19.05 in

It can output about 105db. The vent velocity is acceptable at 30m/sec.

Please keep us up to date.

 

[avaserfi]

Chris seems to have come up with a good one for you with that driver.

Here is the best alignment I could get. It seems more promising vented than sealed, unless you want to use a lot of EQ. Here is the alignment.


Name: Kappa Perfect12.1
Type: Standard one-way driver
Company: Infinity Systems Inc.
Comment: Kappa Perfect series
No. of Drivers = 1
Fs = 23.32 Hz
Qms = 10.28
Vas = 83.28 liters
Cms = 0.208 mm/N
Mms = 224 g
Xmax = 14.15 mm
Sd = 531 sq.cm
Qes = 0.46
Re = 4 ohms
Le = 3.05 mH
Z = 4 ohms
BL = 16.9 Tm
Pe = 350 watts
Qts = 0.44
2.83-V SPL = 96 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square (optimum)
Vb = 4.849 cu.ft
Fb = 18.15 Hz
QL = 6.164
F3 = 19.03 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 4 in
Lv = 19.05 in

It can output about 105db. The vent velocity is acceptable at 30m/sec.

Please keep us up to date.

TLS guy - You are actually modeling the wrong driver. There is the Infinity Kappa 12.1 and there is the Infinity Kappa VQ. The VQ has a certain feature where you can change the Q/BL with certain inserts. When no inserts are used the driver is in "High Q" mode and models extremely well in a 1.5-2.5 cubic foot box.

I will be using the VQ in its "Mid Q" mode in a 3.9 cubic foot box tuned to about 20Hz. Its F3 will be about 20Hz as well and it will be more than capable of breaking 100dB without distortion at that frequency.

 

[TLS Guy]

TLS guy - You are actually modeling the wrong driver. There is the Infinity Kappa 12.1 and there is the Infinity Kappa VQ. The VQ has a certain feature where you can change the Q/BL with certain inserts. When no inserts are used the driver is in "High Q" mode and models extremely well in a 1.5-2.5 cubic foot box.

I will be using the VQ in its "Mid Q" mode in a 3.9 cubic foot box tuned to about 20Hz. Its F3 will be about 20Hz as well and it will be more than capable of breaking 100dB without distortion at that frequency.

Thanks for pointing out the error of my ways. I'm not used to frequenting car audio sites. The pdf for the driver is printing now. I will doodle with it later.

 

[flippo]

Drivers

I'm looking at a sealed box. I'll probably stick with the Dayton RSS315HF-4 12
inch driver and the Dayton HPSA500 500W Subwoofer Amplifier. It will be a couple of months before I start so I am still researching (don't want to get it wrong).

 

[TLS Guy]

I'm looking at a sealed box. I'll probably stick with the Dayton RSS315HF-4 12
inch driver and the Dayton HPSA500 500W Subwoofer Amplifier. It will be a couple of months before I start so I am still researching (don't want to get it wrong).

I have modeled the correct driver now. I have to say that even though this is marketed to the car thump crowd, it has the potential to make an awesome sub. Here are your best options, I think anyway.

First closed box no insert.

Name: Kappa Perfect 12 VQ No insert
Type: Standard one-way driver
Company: Infinity Systems Inc.
No. of Drivers = 1
Fs = 22.9 Hz
Qms = 10.29
Vas = 96.43 liters
Cms = 0.323 mm/N
Mms = 176.4 g
Rms = 2.398 kg/s
Xmax = 16.75 mm
Xmech = 25.13 mm
P-Dia = 250 mm
Sd = 491 sq.cm
P-Vd = 0.822 liters
Qes = 0.79
Re = 4.42 ohms
Le = 1.14 mH
Z = 4 ohms
BL = 11.92 Tm
Pe = 400 watts
Qts = 0.74
no = 0.141 %
1-W SPL = 83.65 dB
2.83-V SPL = 89 dB
-----------------------------------------
Box Properties
Name:
Type: Closed Box
Shape: Prism, square (optimum)
Vb = 4.814 cu.ft
Qtc = 0.74
QL = 12.58
F3 = 27.75 Hz
Fill = heavy


Infinity's alignment.

Name: Kappa Perfect 12 VQ No insert.
Type: Standard one-way driver
Company: Infinity Systems Inc.
No. of Drivers = 1
Fs = 22.9 Hz
Qms = 10.29
Vas = 96.43 liters
Cms = 0.323 mm/N
Mms = 176.4 g
Rms = 2.398 kg/s
Xmax = 16.75 mm
Xmech = 25.13 mm
P-Dia = 250 mm
Sd = 491 sq.cm
P-Vd = 0.822 liters
Qes = 0.79
Re = 4.42 ohms
Le = 1.14 mH
Z = 4 ohms
BL = 11.92 Tm
Pe = 400 watts
Qts = 0.74
no = 0.141 %
1-W SPL = 83.65 dB
2.83-V SPL = 89 dB
-----------------------------------------
Box Properties
Name:
Type: Closed Box
Shape: Prism, square
Vb = 1.25 cu.ft
Qtc = 1.003
QL = 20
F3 = 32.27 Hz
Fill = heavy

Now you might at first sight not see much advantage in the larger box. However there is. Both produce 109 db to just above the F3. However the larger box has a Qtc of 0.74, which is the perfect balance between a box that is over tight and one that is over resonant. The smaller box will just tend to the boomey. I would say the larger box would be a good sounding sub.

Now the vented box. In my view only the low insert is really suitable for vented alignment. I don't care for the sound of high q drivers in vented boxes.


Name: Kappa Perfect 12 VQ low inst
Type: Standard one-way driver
Company: Infinity Systems Inc.
No. of Drivers = 1
Fs = 22.9 Hz
Qms = 10.29
Vas = 96.43 liters
Cms = 0.323 mm/N
Mms = 176.4 g
Rms = 2.398 kg/s
Xmax = 16.75 mm
Xmech = 25.13 mm
P-Dia = 250 mm
Sd = 491 sq.cm
P-Vd = 0.822 liters
Qes = 0.36
Re = 4.42 ohms
Le = 1.14 mH
Z = 4 ohms
BL = 11.92 Tm
Pe = 400 watts
Qts = 0.34
no = 0.141 %
1-W SPL = 83.65 dB
2.83-V SPL = 89 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square (optimum)
Vb = 3.024 cu.ft
Fb = 21.38 Hz
QL = 6.563
F3 = 21.58 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 4 in
Lv = 22.49 in


This is an awesome sub. There is a little ripple between 40 and 60 Hz where the output rises from 109 to 113 db. Vent velocity is a very acceptable 27 m/s. I would recommend one of these over the Dayton. Chris has given you a good tip.

If any body out there is interested I will work up a transmission line sub with the low insert. I have a feeling that would be the mother of all subs. If it were matched to the Thor lines, I would think you could put together a system that would be unmatched at just about any price. I could let anybody interested have the plans for my center TLS using the SEAS coaxial. That is a superb center channel TLS and quite unique.

Get building guys and lets have less of these what speakers would be best threads. Build along the lines I suggest and you will have it!

 

[flippo]

sealed or vented

Ok, at this point if I go with the Infinity kapa perfect VQ12 and use the Dayton 500watt amp (like the idea of the parametric eq), what would be better, sealed or vented? I always heard that sealed were better for music, is this true or opinion?

 

[TLS Guy]

Ok, at this point if I go with the Infinity kapa perfect VQ12 and use the Dayton 500watt amp (like the idea of the parametric eq), what would be better, sealed or vented? I always heard that sealed were better for music, is this true or opinion?

I think either the larger sealed or the vented will be fine. They both will do well on music. You can make a hash of vented and sealed alignments. I don't think either of them will need EQ, not to extend the bass any way. They both have low enough F3 points. It is not I good idea I don't think to extend LF response of vented enclosures with EQ, and that one does not need it. The vented does have that 3db ripple but unless you are unlucky with your room that will not be an issue. If you want the smoothest curve go for the larger sealed alignment. I personally would not use the small sealed as recommended by Infinity as the Qtc is too high for my taste.

If it is general EQ you want there are better places to put the equalizer other than the sub. I would just use a good 400 watt plate amp.

What are your musical tastes.

 

[WmAx]

I have modeled the correct driver now. I have to say that even though this is marketed to the car thump crowd, it has the potential to make an awesome sub. Here are your best options, I think anyway.

The Kappa Perfect *.1 and VQ are extraordinary. They measure superior in disstortion vs. spl as compared to the highly respected Velodyne DD servo subwoofers, which is no small feat, considering the Kappa Perfect has no servo feedback to reduce distortion.

First closed box no insert.

Now you might at first sight not see much advantage in the larger box. However there is. Both produce 109 db to just above the F3. However the larger box has a Qtc of 0.74, which is the perfect balance between a box that is over tight and one that is over resonant. The smaller box will just tend to the boomey. I would say the larger box would be a good sounding sub.

You should not ever exceed much more than 1.5 cubic feet sealed with no insert(high Q). If you do, you reduce power handling and SPL substantially. The driver will radically exceed xmax nearing F3 at rated input power of 400 watts. WinISD Pro was used to model the system. The small box will not be boomy, not one bit, if the single parametic EQ band is set up as I specified.

-Chris

 

[WmAx]

Ok, at this point if I go with the Infinity kapa perfect VQ12 and use the Dayton 500watt amp (like the idea of the parametric eq), what would be better, sealed or vented? I always heard that sealed were better for music, is this true or opinion?

Vented is superior in practical terms, if you don't mind the increased size. It will produce higher SPL and lower practical extension. In a 4-5 cubic foot enclosure vented, a F3 in the 18-19Hz range is easy to achieve. But you need to use a slot vent with large cross section area - this driver can produce high SPL - but only if the port does not compress(which requires a large cross section).

One or the other being better for music is stereotypical myth based on incomplete data and erroneous speculations.

-Chris

 

[TLS Guy]

The Kappa Perfect *.1 and VQ are extraordinary. They measure superior in disstortion vs. spl as compared to the highly respected Velodyne DD servo subwoofers, which is no small feat, considering the Kappa Perfect has no servo feedback to reduce distortion.



You should not ever exceed much more than 1.5 cubic feet sealed with no insert(high Q). If you do, you reduce power handling and SPL substantially. The driver will radically exceed xmax nearing F3 at rated input power of 400 watts. WinISD Pro was used to model the system. The small box will not be boomy, not one bit, if the single parametic EQ band is set up as I specified.

-Chris

Chris is correct. I failed to notice that. The driver exceeds xmax at 25 Hz in the large sealed enclosure. However I doubt you will reach full power in normal use. I agree with Chris in his last post that the vented alignment will likely be better. The Vent dimension I gave you does not have excessive air velocity at 27m/sec. That is very typical of commercial designs. I don't like huge vents because of port resonance issues.

If you want I will work up a TL. I have a feeling this driver is asking for that. That would be the best of all if it proves suitable.

If you use the small closed box, Chris can guide you about the EQ. I'm old school I guess, and like my speakers correct without EQ. I personally would not build a speaker with a Qtc that high, but I'm sure Chris's instructions will make it work for you. Your getting into a new versus old generation issue here, I'm afraid. I'm sure you have concluded I'm the old geyser.

 

[flippo]

Thanks for all the help. I know audio and speakers and such but am a newbie in diy - I was thinking of building my mains a couple of years ago but decided against it. Not sure I could master the crossover construction correctly but feel I can handle construction of sub once i get all the dimensions needed. I will follow advice to do a vented design by chris using a slot- One question, is this just a slot of given dimension or is there a slot port you purchase? I also would like to buy software for designing the box, thinking of
BassBox Lite Software CD-ROM from parts express.

Again thanks for all the help. I will definitely take pictures of process and show finished project.

 

[flippo]

musical tastes

You asked about musical tastes and I listen to about everything- I really like Jazz (tradional, vocal and fusion) and Prog rock (Kansas being my favorite).
Don't like hip hop or rap at all.

 

[TLS Guy]

Thanks for all the help. I know audio and speakers and such but am a newbie in diy - I was thinking of building my mains a couple of years ago but decided against it. Not sure I could master the crossover construction correctly but feel I can handle construction of sub once i get all the dimensions needed. I will follow advice to do a vented design by chris using a slot- One question, is this just a slot of given dimension or is there a slot port you purchase? I also would like to buy software for designing the box, thinking of
BassBox Lite Software CD-ROM from parts express.

Again thanks for all the help. I will definitely take pictures of process and show finished project.

If you use the slot, you will have to construct a tunnel. The idea is to use a larger diameter pipe, and then it has to be longer. With the vent dimensions I gave you, a port flared at BOTH ends 4 inches in diameter and 22.5 inches long, has a max vent air speed velocity of 27 m/sec. That is less than 25% of the velocity of sound. That is very acceptable. You should be able to get that vent in the cabinet and still keep it away from the opposing wall. Now if you use larger vents, and construct from MDF you will have a large volume of air and run the risk of that also resonating.

If you want you can use two 3 inch diameter ports each 26 inches long and flared at both ends. That gives you a vent airspeed of 24 m/sec. That gives you are margin of around 10 m/sec before it would be anything I would worry about. I would build it with flared ports.

I'm sure you will complete this project well. Brace it very well. Remember to add the volume of the driver, bracing and amp to the total volume. The volume of the speaker is 0.108 cu.ft It will on hell of a sub.

 

[annunaki]

Port resonance is not going to be much of an issue unless one has an extremely large slot vent i.e. over 45 sq. in. I would suggest something along the lines of 26 sq.in.-30 sq.in. Not only will it increase output slightly but you will have very low port compression and the port resonance will be well above the operating range of the system.

A 2" x 13" slot vent would work very well.

 

[avaserfi]

Port resonance is not going to be much of an issue unless one has an extremely large slot vent i.e. over 45 sq. in. I would suggest something along the lines of 26 sq.in.-30 sq.in. Not only will it increase output slightly but you will have very low port compression and the port resonance will be well above the operating range of the system.

A 2" x 13" slot vent would work very well.

For my VQ build a 3" x 12.5" x 56" slot port will be used. The resonance band of the port will be about 120Hz so a steep electronic crossover (likely 48dB per octave) will be used along side four 1/2" radius dowels inside each layer (there are two) of the port to strengthen it and further reduce any possible resonance.

Just another option to avoid annoying problems like resonance .

 

[TLS Guy]

Port resonance is not going to be much of an issue unless one has an extremely large slot vent i.e. over 45 sq. in. I would suggest something along the lines of 26 sq.in.-30 sq.in. Not only will it increase output slightly but you will have very low port compression and the port resonance will be well above the operating range of the system.

A 2" x 13" slot vent would work very well.

With that size slot vent the length of your tunnel will be 50 inches. Vent air velocity will be 14 m/sec. You will have to wind that around at least one corner, so the air flow in the port will not be that linear.

You could use multiple long tubes and use elbows. You will need to visit the plumbing supply and and get Oatey cement and the right bits of plastic drain tube as well as the flared ends. The flared ends will have to come form Parts X-Press or Madisound. I have seen constructors in audio x-press and speaker builder use several curved pipes. Then you can get nice smooth curves.

Two 4 inch tubes flared at both ends 47.25 inches long, also have an air velocity of 14 m/sec. I think the flow would be less turbulent than with the duct method.