Build or Buy?

[notdedyet]

Hi;
I've decided it is time to add a new sub to my home theater. I've been doing alot of reading on this site, and have kind of fallen in love with the thought of getting a HSU stf-2. I haven't been able to hear one, but from the discussions on this forum and reviews elsewhere, I'm sure that I would be happy with it. It looks like I can get one for $379.00 delivered. The only thing stopping me is that I have also been considering building a sub to save some money. I am thinking about using the reference 10 HF sub from Parts Express and the 240 watt plate amp. I have been modeling using winISD and it looks like I can get good results with a vented box of 2 cubic ft with a tuning frequency of 23hz. I am confident that I have the skills to build a quality box and have the tools available. I can build the sub for about $100.00 less than buying the HSU. The question is: can I get results that I would be as happy with as if I get the HSU? What do you think?

 

[TLS Guy]

Of course you can

Yes, you can roll your own. Speaker building is great fun, and will teach you a lot. When I get time I will double check your alignment. I'm just leaving the Twin Cities for Benedict. I will look at your project later this evening or tomorrow.

I have been helping a guy in Milwaukee build this set of speakers via the NET. As you can see it is getting close to listen time. He sent me these pictures two days ago.

http://mdcarter.smugmug.com/gallery/3191208#224564206

Here is my last construction project.

http://mdcarter.smugmug.com/gallery/2424278#127083295

Stay in touch!

 

[notdedyet]

Thanks. I really appreciate your looking at the alignment. As I said, the actual building is not a problem, but the design is what I'm a little leary of.

 

[TLS Guy]

Save big

Building your own speakers, assuming you want to properly educate yourself, is the best way to save money. We will build a better sub!

 

[Warpdrv]

Yes, you can roll your own. Speaker building is great fun, and will teach you a lot. When I get time I will double check your alignment. I'm just leaving the Twin Cities for Benedict. I will look at your project later this evening or tomorrow.

I have been helping a guy in Milwaukee build this set of speakers via the NET. As you can see it is getting close to listen time. He sent me these pictures two days ago.

http://mdcarter.smugmug.com/gallery/3191208#224564206

Here is my last construction project.

http://mdcarter.smugmug.com/gallery/2424278#127083295

Stay in touch!

Those look great TLS... very nice...

Im in Milwaukee, and would love to hear the finished product...


notdedyet
If you have the patience and ability to build your own, you can have a far greater product in the end for a great savings... TLS can easily help you in this manner...

 

[abboudc]

Hi;
I've decided it is time to add a new sub to my home theater. I've been doing alot of reading on this site, and have kind of fallen in love with the thought of getting a HSU stf-2. I haven't been able to hear one, but from the discussions on this forum and reviews elsewhere, I'm sure that I would be happy with it. It looks like I can get one for $379.00 delivered. The only thing stopping me is that I have also been considering building a sub to save some money. I am thinking about using the reference 10 HF sub from Parts Express and the 240 watt plate amp. I have been modeling using winISD and it looks like I can get good results with a vented box of 2 cubic ft with a tuning frequency of 23hz. I am confident that I have the skills to build a quality box and have the tools available. I can build the sub for about $100.00 less than buying the HSU. The question is: can I get results that I would be as happy with as if I get the HSU? What do you think?

Today only, you can get an AV123 ULW-10 w/500 watt amp for $279 (black) or $299 (rosewood). That's going to be tough to beat. The finish is gorgeous and would be impossible to duplicate with a DIY job IMO.
Certifiably Mad Mark Sale

 

[notdedyet]

Abboudc;

Thanks for the heads up, but I'm really leaning towards building one myself

 

[TLS Guy]

Hi;
I've decided it is time to add a new sub to my home theater. I've been doing alot of reading on this site, and have kind of fallen in love with the thought of getting a HSU stf-2. I haven't been able to hear one, but from the discussions on this forum and reviews elsewhere, I'm sure that I would be happy with it. It looks like I can get one for $379.00 delivered. The only thing stopping me is that I have also been considering building a sub to save some money. I am thinking about using the reference 10 HF sub from Parts Express and the 240 watt plate amp. I have been modeling using winISD and it looks like I can get good results with a vented box of 2 cubic ft with a tuning frequency of 23hz. I am confident that I have the skills to build a quality box and have the tools available. I can build the sub for about $100.00 less than buying the HSU. The question is: can I get results that I would be as happy with as if I get the HSU? What do you think?

Dear Notdedyet,

Here are the alignments.

For Vented the alignments are as follows: -

Vb 1,546 cu.ft.
V(total) 1.581 cu.ft.
QL 6.885
F3 26.21 HZ
Fill Minimal

Vents 1 round, both ends flared.
Diameter 2 in.
Length 11.45 in.

This gives a nice curve with only 1.5 db of ripple at 75 Hz

The only things that bother me are that the vent diameter can not be greater the 2 inches, or the vent gets far too long. I have specified a flare at both ends, but I am concerned about vent noise. The Qts of the Dayton RSS265HF-4 is 0.39, which is getting towards the high end for a B4 reflex.

I did run a closed box alignment.

Vb 0.459 cu.ft
Qtc 0.707
QL 20
F3 48.84
Fill Heavy.

There is less than 1 db of ripple. If the amp were equalized to boost 12db per octave below 50 Hz, that likely would give the optimal performance. It would of course take considerably more power from the amp.

In the reflex design if the port faces away from the listening area, or faces the floor, then I think results would be very acceptable.

The enclosures will have to be well braced, with interlocking MDF boards, glued to 1/8 inch router grooves.

You need to calculate and estimate the volume of the braces, amplifier and driver and add that to the total volume.

I hope this helps you get started.

 

[annunaki]

A 2" vent diameter is WAY too small on any subwoofer tuned that low. It is too small for any subwoofer really. You would need at minimum a 3" diameter port for that driver.

Upon modeling the driver in question, I get a vented enclosure at 2.5 cu.ft. net with a tuning frequency of 21hz.

In order to keep the vent noise below audible limits I recommend a slot vent of 1.5" x 12.5" and 41.5" long. This allows sufficient port surface area. In order to get sufficient vent area, the slot vent is recommended as it will be easier to "fold" into the enclosure.

With a lowpass 4th order crossover (24db/oct.) I get anechoic frequency response of 23hz-69hz +/-1db! The -3db points on the low end and the high end are 19.8hz and 81hz respectively. With this being simulated anechoic response, in room response will be even deeper on the low end.

 

[TLS Guy]

I didn't like it either

I didn't like it and redid it

Name: Dayton RSS265HF-4
Type: Standard one-way driver
No. of Drivers = 1
Fs = 22 Hz
Qms = 2.8
Vas = 60.03 liters
Cms = 16.04 mm/N
Mms = 3.262 g
Rms = 0.161 kg/s
Xmax = 0.551 mm
Xmech = 0.827 mm
P-Dia = 80.84 mm
Sd = 51.33 sq.cm
P-Vd = 0.00283 liters
Qes = 0.45
Re = 3.3 ohms
Le = 3.3 mH
Z = 3.96 ohms
BL = 1.819 Tm
Pe = 350 watts
Qts = 0.39
no = 0.137 %
1-W SPL = 87 dB
2.83-V SPL = 2.83 dB
-----------------------------------------
Box Properties
Name:
Type: Vented Box
Shape: Prism, square (optimum)
Vb = 2.617 cu.ft
Fb = 18.6 Hz
QL = 6.651
F3 = 21.7 Hz
Fill = minimal
No. of Vents = 1
Vent shape = round
Vent ends = two flared
Dv = 3.25 in
Lv = 23.43 in

That keeps the vent velocity to 10% of the speed of sound. If the vent is too large, then you get port resonances which really spoil things. The vent is nearly 2 ft so it would have to be a curved tube. The previous vent had a velocity of 42 m/sec, which as I said was a little high. According to my simulation if the vent os any larger then vent resonances are a problem.

 

[WmAx]

A 2" vent diameter is WAY too small on any subwoofer tuned that low. It is too small for any subwoofer really. You would need at minimum a 3" diameter port for that driver.

Actually, even a 3" port is entirely too small, if substantial compression directly at and around the port tuned frequency is to be avoided. As an example, my computer subs, a couple of 10" Infinity Kappa Perfect 10.1 units, are in enclosures with a tuned port frequency of about 25Hz using a 3" I.D. port with 3/4" radius on the inside and outside port terminations. Actual port compression is over 20dB(!) with this particular driver centered on the tuning frequency of the port. As an example, with both drivers operating at the same time, 119db is possible(with low distortion) measured at 30Hz. At 25Hz, about 95dB is possible, and the wind velocity is so high that it can blow paper that is sitting 6 ft away on the floor in front of the port.

-Chris

 

[TLS Guy]

Port velocity versus port resonace

Unfortunately we are up against one of the big conundrums of reflex loading. If the port is too small then velocity can be too high. Although in practice velocities below 35 m/sec are acceptable. If the port is too big, then port resonances will really spoil the cake, especially in cabinets tuned to very low F3. That is were port resonances become problematic. My program tells me when port resonances are in the problem zone.

That is another reason I favor the transmission line loading.

 

[annunaki]

The first port resonance on my example given was at 175hz. This will not be a problem with a 4th order slope at 80hz.


WmAx,

While I agree that port compression can be an issue with a 3" port, its performance overall would be acceptable by a vast majority of folks. Especially if one is buliding the enclosure with somewhat limited DIY experience. A 4" or larger vent increases the length greatly in a 2.5 cu.ft. enclosure when tuning around 21-22hz or so. As I suggested, it would be at an absolute minimum diameter allowable.

In my design I recommended a slot vent with 18.75 sq.in. of port surface area. This will allow sufficient airflow without much port compression and allow a high port resonance out of the operating bandwidth.

 

[notdedyet]

Thanx to everyone who has participated in this thread so far. With much guidance from TLs Guy, I have decided to build my own sub. I am going with a Scan-Speak 26W/8861T-00 Reveltor driver in a ported 2.807 cu ft box. If I can keep from screwing it up, TLS has assured me it will be awesome! I'll keep you updated and post some pictures along the way. Cross your fingers for me

 

[annunaki]

What is the cost of the driver you will be using? What amplifier will you be running it with?

Scan Speak builds excellent drivers but they tend to be fairly pricey. While it should do very well musically I just hope it has the oomph on the low end. The excursion is pretty meager on such a high caliber driver. Sure it is probably linear, but most subs can be very linear at just 9mm one way linear excursion. For nearly half the price you can get the dayton and get at least 95% of the performance of the ScanSpeak with more output.

If you are going to spend that type of money, I would do the JL audio 10W3v3. It will be just as linear or more so than the scan speak and give you significantly more excursion. It will sound just as good for music and give you more output for movies.

 

[notdedyet]

annunaki;
Here is a link to the driver that I purchased:http://www.madisound.com/catalog/product_info.php?manufacturers_id=148&products_id=953
I hope this link works, as I am not that good at this.
I have already bought this item and it is on it's way. I am going to power it with the 240 watt amp from dayton @ Parts Express.

 

[annunaki]

annunaki;
Here is a link to the driver that I purchased:http://www.madisound.com/catalog/product_info.php?manufacturers_id=148&products_id=953
I hope this link works, as I am not that good at this.
I have already bought this item and it is on it's way. I am going to power it with the 240 watt amp from dayton @ Parts Express.

It is too bad you already purchased the sub. There really are better options for a home theater driver. It should do superbly for music if you are not a bass head. The sub starts rolling off at 50hz and has a -3db point of 27.8hz.

It is an excellent woofer to use as part of a three way tower, but a waste of money as a home theater sub or as a sub at all in my opinion.

As you can see below the woofer reaches maximum excursion at just 46hz and would continue to behave in a non-linear fashion down to 30hz. Essentially the woofer is useless from 30hz-46hz as it would be bottoming out with rated power.

In this shot we can see the woofer rolls off quite early and is already down by -3db at 27.8hz. Taking into account that the woofer would be bottoming with rated power to achieve this, it more or less completely rules it out as a true dedicated subwoofer.

I would try to see if I could cancel my order and or return the sub for minimal fee or for free. This woofer, though great for woofer purposes in a three way speaker design, is simply not cut out for subwoofer duties. It would easily be bested by the Dayton High Fidelity woofer with flying colors. For the same price it would be outclassed by a mile by the JL 10W3v3.

Sorry that you already purchased the sub. Hopefully you can get your money back.