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pkgum 27th October 2001 05:47 PM

I am making a subwoofer for a very high excursion 15" subwoofer driver called 15"HE manufactured by TC sounds
( )This subwoofer must be flat to around 20Hz.
This subwoofer will be used for music, so which type of enclosure is best...ported or sealed?

TCsounds 15"HE Theiele/small parameters

Fs 25Hz
Qts .24 ?20% (I have no idea what '?20%' means)
Vas 132 Litres
Xmax 3 inches peak to peak
SPL 90 ?2dB
Sd 732cm2

There were some problems when designing a sealed enclosure for this driver. The enclosure volume came out very small at 17.2 Litres with a qtc of 0.707 However, the bass-cut off Frequency (F3) was too high at 73.7Hz I want much lower bass than this There must be something wrong

There were also problems when designing a ported enclosure for this driver. The enclosure volume came out small at 33Litres. However, F3 was too high at 47.93Hz. The tuning frequency was also too high at 37.93 Hz. I want a subwoofer that is flat to around 20Hz

Is there a minimum port diameter with a driver that has a Xmax this big? ( 3 inches peak to peak )

all this tech jargon is blinding me

Super 27th October 2001 06:11 PM

First off, what enclosure design program are you using? I dont think that some of those numbers sound right. Also, have you seen the vas for this driver?! 132 liters! This is far beyond the reach of most DIYers for in home use, and it seems that this is strictly a subwoofer designed for in car use. Also, these drivers were designed to be used with a minimum of 500 watts power in mind. It seems that this driver was designed for high SPL output, rather than to go low. Their other 15 inch driver seems to be a far superior choice for in home use, which even still has a vas of well over 200 liters! Not only is it unlikely that you will make this driver linear down to 20 hz, but it is unlikely that you will have success in designing an enclosure, unless you have the driver specs measured, due to the shoddy +- 20% measurements that are given.

ThomasW 27th October 2001 06:59 PM

Here ya go.....
Well what do they say "been there, done that". :) This design is optimized for the HE15 in the smallest possible ported box. Tuning is 18.56Hz, I don't recommend tuning any lower.

If you have LspCAD or BassBox Pro 6, I can email you the model files, if I remember where they are.....

We found the published HE-15 T/S parameters are somewhat 'optimistic', as compared to our measurements of the drivers we received. But the driver still performs quite well. The Fs is really in the 28-29Hz range after extensive break in. The efficiency is closer to 84-86db in most enclosures.

You will need parametric EQ with any alignment. The driver has a pretty good size hump around 70Hz due to the VC inductance, (see the CLIO measurements page on the Klone project site for specifics). A Behringer DSP110P is a good inexpensive choice

I'm working an a klone of the Krell MRS. Will be using 2 BluePrint 1503. These are for all intents and purposes identical in performance to the HE15.

BTW, If you deside to go with a sealed box seriously consider using a Linkwitz Transform circuit to optimize the performance in a smaller box

The AS-15 Project

[Edited by ThomasW on 10-27-2001 at 01:50 PM]

pkgum 28th October 2001 01:31 AM

reply to super: First off i dont think these drivers are not just for car use. This is becuase they are used in the $28000 Krell Master Reference Subwoofer, the stryke project, and a "PR" subwoofer in the website below:

For sealed enclosures, I am using a program called 'AJ Sealed Designer'downloaded from
For ported enclosures, I use the website java calculator at:
I cannot use WinISD because it does not list the tc sounds driver in the database.

You are right, the other 15" driver is much easier to design..but it has only 2 inch peak to peak Xmax.I prefer the 15"HE because it has 3 inches Xmax. I can think of no other driver that comes this close in extreme excursion.
Note: I like ultra exursion bass drivers that go low and can anyone suggest any other driver that can compete with the 3 inch peak to peak Xmax TC sounds 15"HE?
(The NHT 1259 with 26mm peak to peak Xmax does not qualify)
Lastly, are u saying that it is impossible for me to make enclosures for the TC sounds drivers without special equipment because their parameters are not accurate enough?

Reply to thomas: HOW CAN U TUNE THE VENTED BOX TO 18.56hz WHEN MY READINGS SAY THAT THE TUNING FREQ for your stryke 15"HE driver should be 29.95hz? Is there something wrong?
And what is a parametric equaliser?? This is getting really technical

ThomasW 28th October 2001 02:14 AM


The Krell MRS uses a drivers similar to the HE15 that yes are made by TC-Sounds, but they have a less sophisticated design. Here's a pic of an open MRS so you can see their drivers. These are actually closer in design to the BP1053 but with a smaller magnet structure

'Topless' Krell MRS


Stryke HE-15

Understand that the tuning of a ported box has nothing to do with the T/S parameters of the driver. The tuning is purely a function of the size of the box, combined with the size of the port and nothing else. The T/S parameters are needed only if you want to 'model' the performance of the driver in the box.

Now do you own a HE-15? If not, I doubt that you'll be able to buy one since the second special purchase was several months ago, and these aren't 'stocked' by Stryke

If you don't own a HE-15 take a look at the 1503 from These have almost identical performance to the HE-15, are much cheaper and are in stock.

Enter the T/S parameters into WinISD. Or for a more accurate model if you have MS Excel download a copy of Unibox from and enter these HE-15 T/S parameters, they are from our testing. Chose 18 or 19Hz as the Fb for the design.

Fs: 28.5 Hz
Qms: 6.0
Qes: .345
Qts: .326
Vas: 106.7 L
Re: 6 ohm
BL: 27.3 Tm
no: .529%
1W SPL: 86 dB
Cms: .145 mm/N
Mms: 257 grams
Rms: 7.0 kg/s
Xmax: 22.85 mm
Sd: 720 cm^2
Vd: 6.5L total
PEmax: ~ 2000W

A parametric EQ is one that has variable frequencies and bandwidths instead of fixed ones like a 1/3 octave EQ.

If your now completely lost I'll help design a cabinet if you own a driver, either the HE-15 or BP-1503.

Hope this helps.....


[Edited by ThomasW on 10-27-2001 at 10:53 PM]

pkgum 28th October 2001 04:35 AM

Nope..i havent bought the 15HE
I've decided to go with a vented this a wise decision since the sub will be used for music...not home cinema
lve actually seen the BP1503 before. I thought it was one of those poor quality cheap drivers because of the dramatic price difference..stryke 15HE- $1000 BP1503-$219
what makes the BP so cheap? Can it produce clean bass to 16Hz? If so..i choose the BP..its so much cheaper

If you are saying the tuning of the ported box has nothing to do with T/S parameters, then what is the tuning freqenency used for?
Also...are there any guidelines or reasons that say which frequency you should tune the box to?

My aim is to build a subwoofer that can produce bass with good, strong and clean output to 20Hz..16Hz is even better because it can compete with pipe organs

F3 for the BP1503 is 37.6Hz----does this fulfil my aim?
Fb for the BP is 33.26Hz-----does this fulfil my aim?

Both frequencies are in the thirties...does this mean that it has limited output in the low 20Hz region?

Do you have more specs for the BP? The site does not list its nominal power rating, its Le (so-called Equivalent Voice Coil Inductance), and its "series resistance"
(all this technical jargon and mumble jumble).

[Edited by pkgum on 10-27-2001 at 11:39 PM]

Super 28th October 2001 05:02 AM

A vented enclosure can generally go lower than a sealed enclosure, but will tend to trade off "tightness" or speed in the lower octaves. Because of this, several music-only subs are sealed. However, if you want to go deep, I'd stick with the ported enclosure, and often, there is a minimal difference if a quality driver is used. (I use my ported SonoSub for music and HT alike, and found it to outperform many sealed commercial designs, including Velodyne and REL, using only a single Shiva driver)

Also, would you be willing to consider using stereo subs? I've often found that using two drivers that have similar performance to the bigger brother or more expensive drivers can often outperform the "bigger brother" when two drivers are used. If you were able to get your hands on the HE15, its not unlikely that you will get better performance out of two BP1503's, because each driver will only have to do half as much work, thereby decreasing distortion. Heck, for only $219 per driver, you could build four subs for the price of one! The odds of that one driver outperforming 4 drivers of comparable specs is highly unlikely. GRollins, for example, uses SEVERAL 12 inch subs (a LOT more than four), and achieves disgusting SPL's well into the 16hz range and beyond, despite using fairly inexpensive drivers. (Dayton Titanic drivers if I recall correctly)

As for things that make one driver cheaper than another, well, there are several things. Power handling is probably one of the biggies. There is also the amount of material that goes into making the cone, and also the quantity that the drivers are manufactured in. However, whether theres $800 dollars worth of difference is up to you. Personally, I'd go with multiple subs using the more inexpensive drivers.

[Edited by Super on 10-28-2001 at 12:05 AM]

ThomasW 28th October 2001 06:56 AM


When the Stryke HE-15 preorder sales are offered the cost of the HE15's are approx $400ea. I paid less for my 2 because I bought in a presale a year ago December. My understanding is that there may be a few HE-15's available for $425ea

The $1000 'list' price is because Audiobahun the German company that buys the largest number of the drivers from TC-Sounds and sells them for $1000; told TC-Sounds that if Stryke stocked and sold the HE15 for $400 as a regular stock item, there would be legal trouble.

The BP10503 don't use custom designed parts and aren't built as a special order item. They use high quality stock off the shelf parts assembled properly. Also they don't have an aluminium cone and dust cap, double spider, or VC leads woven into the spider. So unlike the HE-15 it's not audio jewelry, but it's a very good driver at a very good price.

I dare say that in a A/B comparison (HE-15 vs BP1503) it would be very difficult if not impossible to tell the difference in a shootout. Understand I own both these drivers so I do speak from experience.

Note neither of these drivers will go down flat to 16Hz. They both do fine down to approx 18-19Hz though.

As I stated before the tuning frequency is related to the box not the driver. But you can't randomly choose an Fb and have any driver work well there. That's why both the HE15 and 1503 should be used in a vented box tuned to between 18-19Hz

Here is a copy of the DUMAX testing done on a BP1053


It's important to look closely at the specs of these high excursion drivers. They have a Vd greater than 6 liters, that's equal to multiple 12"s. And they have power handling abilities that are correspondingly high as well. They certainly aren't for everyone's taste. But if a 'portable' sub having the ability to play at rock concert SPL's day in and out is needed, these will do the job. BTW, the sound quality of the AS-15 design is extremely good. I built one of the Stryke cubes with the PR's and wasn't impressed.

Also having 12-12" drivers isn't something exclusive to GRollins. This is my primary sub, a dozen Shiva IB config, just about 2yrs old. It's about 7db down at 10Hz from a reference level output of 100db. Max output is around 130db@20Hz. Measurements were made with a calibrated B&K 4133 using a CLIO system

[Edited by ThomasW on 10-28-2001 at 01:22 AM]

pkgum 28th October 2001 08:33 AM

some questions...

My aim is to build a subwoofer that can produce clean strong bass to around 18Hz

F3 of the BP1503 enclosure is 37.6Hz----is this alright?
Fb of the BP1503 enclosure is 33.26Hz-----is this alright?

Both frequencies are in the thirties...does this mean that the subwoofer has small output in the low 20Hz region?

To thomas: How did you know that u should tune the BP1503 enclosure to 18-19Hz?
Are there any guidelines as to what frequency i should choose to tune the vented enclosure?

You said the tuning of the ported box has nothing to do with "T/S parameters" (tech jargon), then what does the tuning freqenency indicate?

ThomasW 28th October 2001 03:35 PM



You said the tuning of the ported box has nothing to do with T/S parameters, then what is the tuning freqenency used for? What does it indicate?
As I've stated, Fb indicates the frequency the box with its port is tuned to. Think of a ported box as something similar to pop bottle, and you're blowing across the top. If the size of the box, combined with the diameter and length of the port are tuned to 18Hz, when you blow across the port a 18Hz tone is produced. Now this is a bit over simplified.....

Fb = Enclosure resonance (usually for bass reflex systems), in Hz
F3 = -3 dB cutoff frequency, in Hz

To better understand this go to the 'Calculate Your Vent Length' section of the website you're using for ported designs
Now type in quantity of ports =1
Enter volume of enclosure =8 ft3
Enter desired tuning frequency = 8Hz
Enter desired port diameter =6"

You'll get a port length of 25.01".

This is how you tune a box to 18Hz without having or using any T/S parameters. Now I'm not suggesting that this is how to design a sub. It's just an example of how to tune a box.

All woofers roll off as the frequencies drop. The port in a reflex design only serves to add some additional boost around the tuning frequency (Fb). Where as a sealed box rolls off at a fixed rate.

Depending on the amount of room gain, EQ will most likely be required to get flat response from any sub down to 18Hz.

You might want to pick up a copy of "The Loudspeaker Design Cookbook" by Vance Dickason. This is a good book to get a grasp of the what/why/how of speaker design.


[Edited by ThomasW on 10-28-2001 at 09:37 AM]

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