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Home Subwoofer Project (car audio driver questions)
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Old 15th May 2014, 12:52 PM   #1
mart34 is offline mart34  England
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Default Home Subwoofer Project (car audio driver questions)

Hi,

I’m considering a Home Subwoofer Project, but being in the UK, I am struggling to find high end drivers. I’m looking for an 18” high output driver. So far, all I have come across is car audio drivers that meet my specification.

As far as I know, the only thing to look out for when going for a car audio driver over a home audio driver, is the Fs, which apparently is normally lower on home audio drivers, due to the fact that car audio drivers are designed to take advantage of cabin gain, due to the volumetrically small cabin increasing the volume of lower frequencies, and are therefore the drivers are not designed with low Fs, just in case there is too much peaking at their Fs when in the car.

So what would a high Fs look like ? I am currently looking at a Sundown Audio Zv4 18”, which has an Fs of 27.4Hz. This to me still sounds low.

These are approx £630 in UK. I would like a TC Sounds LMS 5400 Ultra, but it’s looking to be over £1000 when including shipping / import and customs taxes.

The Sundown Audio Zv4 18” TS parameters are as follows:

Also, their website states “The linear x-max is around ~35mm one-way by 70% BL with a total mechanical clearance of OVER 60 mm in the motor!”
What does 70% BL mean ? Is this just rubbish sales jargon ? Obviously 35mm is the Xmax, and I assume 60mm is the Xmech.

Fs: 27.5 Hz
Re: 3.6 ohms
Qms: 5.45
Qes: 0.49
Qts: 0.45
Cms: 0.08
Mms: 394 g
BL: 22.4
Vas: 67.7 L
Sens: 86.4
Le: 2.2
RMS: 1750 watts
Xmax 35mm linear one way



Any advice would be greatly appreciated.

Many thanks
Martin
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Old 15th May 2014, 03:23 PM   #2
Inductor is offline Inductor  Portugal
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Quote:
Originally Posted by mart34 View Post
“The linear x-max is around ~35mm one-way by 70% BL with a total mechanical clearance of OVER 60 mm in the motor!”
What does 70% BL mean ? Is this just rubbish sales jargon ?
No. I'm not in the manufacture process and never used this parameters but it's a way of saying that for an "equivalent Xmax", that is/or should be usually measured as a percentage of distortion", in this case with BL, that the voice coil is out of the gap where the percentage is 70%. 70% or 50% are usually used. Xmech or Xlim in another sense are the mechanical destruction of the driver because of the failure of one of it's (driver) components achieving it's limit. The industry doesn't like to measure things and show to the public. It's time consuming and costs money, besides, they (some) think is bad marketing to make money when the client doesn't know about a thing. So, they find ways not to measure real distortion (Xmax) (anechoic chamber) saying; hey! you have only 70% of BL with this excursion.
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Old 15th May 2014, 03:44 PM   #3
GM is offline GM  United States
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Greets!

Low Vas that ‘helps’ to dictate acoustically tiny cabs and the excessively long vents as a consequence and high inductance that limits usable HF response are other main differences between high SQ and car audio [sub] woofers. Note that these technical ‘shortcomings’ are generally a plus for tapped alignments.

No ‘rubbish sales jargon’, research ‘Klippel’ to learn about high power distortion measurements, limits.

'Low' is relative. Ideally you want an Fs that's at, or below, the lowest frequency you want to reproduce at a tonally balanced [i.e. 'flat'] output in room, so if the lowest is a concert grand piano, then ~27.5 Hz or ~31.5 Hz for a [5] string bass guitar or ~16 Hz for some pipe organ symphonies. Movie LFE and other special effect recordings can require 7-8 Hz unless filtered out.

If a tapped TL/horn is used, then Fs can be anywhere from a little bit to > an octave higher in each case depending on the driver’s specs, performance level required and available space.

So, what are your desired performance goals, space limitations?

GM
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Old 15th May 2014, 03:53 PM   #4
Inductor is offline Inductor  Portugal
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Quote:
Originally Posted by mart34 View Post
The Sundown Audio Zv4 18” TS parameters are as follows:

Also, their website states “The linear x-max is around ~35mm one-way by 70% BL with a total mechanical clearance of OVER 60 mm in the motor!”
What does 70% BL mean ? Is this just rubbish sales jargon ? Obviously 35mm is the Xmax, and I assume 60mm is the Xmech.

Fs: 27.5 Hz
Re: 3.6 ohms
Qms: 5.45
Qes: 0.49
Qts: 0.45
Cms: 0.08
Mms: 394 g
BL: 22.4
Vas: 67.7 L
Sens: 86.4
Le: 2.2
RMS: 1750 watts
Xmax 35mm linear one way
It's better to post a link to the drivers specs than wrong data in this case.
(Looks more you posted the specs for the 15" driver)
Z v.4 Series
There are 2 drivers "Sundown Audio Zv4 18" a D1 (1R7) and a D2 (3R6).

This driver in a sealed application 150L has F3 37.5 Hz.
This driver is great for a TL/quarter-wave project.
In a reflex (Enclosure Recommendations) you can expect "crazy" references for the enclosure like long ports, extra size enclosures (>150L) and funny output curves (roll-off), F3 ~20Hz with a 200L (net).
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Old 15th May 2014, 04:32 PM   #5
GM is offline GM  United States
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Quote:
Originally Posted by Inductor View Post
It's better to post a link to the drivers specs than wrong data in this case.
Beat me to it! WinISD Pro’s specs:

GM
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File Type: gif ZV4-18_D2 WinISD Pro specs.gif (13.5 KB, 149 views)
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Old 16th May 2014, 12:40 PM   #6
bjorno is offline bjorno  Sweden
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Hi All,

FYI:

b
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File Type: jpg Sundown Audio Zv4.JPG (649.5 KB, 135 views)
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Old 16th May 2014, 11:44 PM   #7
mart34 is offline mart34  England
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Thanks for everyone's input. My apologies about putting up the incorrect TS parameters.

My main goal is to have a subwoofer which is capable of reaching low frequencies and at high amplitude for Music. I only want a single driver, and am certain it's going to be this 18" Sundown. I have two pairs of Mordaunt Short floor standing speakers which I use in Stereo (four floor standers up front), and their response is 45Hz - 22kHz @ -3dB. Therefore I would like to subwoofer to be designed for say no more than 100Hz (max) and frequency filterwill be fine tuned once running.

Based on what you have said, I think its safe to rule out sealed.
I can do ported, but If I went down the Transmission Line route, I would need to do a lot of research.

I have recently downloaded WINISD, and am still playing around with it. Is it possible to model TL in Winisd ?
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Old 17th May 2014, 01:12 AM   #8
Inductor is offline Inductor  Portugal
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Quote:
Originally Posted by mart34 View Post
My apologies about putting up the incorrect TS parameters.
Did you mention them after all (?)... (where is my head???)
Z-18 D1 TS Parameters http://www.sundownaudio.com/misc/201...%2018%20D1.JPG
Z-18 D2 TS Parameters http://www.sundownaudio.com/misc/201...%2018%20D2.JPG
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Old 17th May 2014, 02:15 AM   #9
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by mart34 View Post
Thanks for everyone's input. My apologies about putting up the incorrect TS parameters.

My main goal is to have a subwoofer which is capable of reaching low frequencies and at high amplitude for Music. I only want a single driver, and am certain it's going to be this 18" Sundown. I have two pairs of Mordaunt Short floor standing speakers which I use in Stereo (four floor standers up front), and their response is 45Hz - 22kHz @ -3dB. Therefore I would like to subwoofer to be designed for say no more than 100Hz (max) and frequency filterwill be fine tuned once running.

Based on what you have said, I think its safe to rule out sealed.
I can do ported, but If I went down the Transmission Line route, I would need to do a lot of research.

I have recently downloaded WINISD, and am still playing around with it. Is it possible to model TL in Winisd ?
Hi,

As you can see it is possible to tune the FR lower for this Driver that is Power limited, not by the displacement of the Cone.

To maintain a low Air velocity at Max. Power: You cannot decrease the Terminus CSA much more than I have done.

WinISD is pretty useless for any quarter-wave Box simulation (even if trying to extrapolate with Layman Wishful thinking) other than for very simple Sub-woofer designs like Beginners Closed or BR Boxes.

Download the HR Program instead.

Look up HR for Dummies(Google) and try to understand and master the input Screen and Wizard's that is second to none if compared to WinISD simple predictive outcomes.

b
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File Type: jpg Sundown Audio Zv4_OD-TL.JPG (591.0 KB, 112 views)
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Old 17th May 2014, 09:34 AM   #10
mart34 is offline mart34  England
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Quote:
Originally Posted by Inductor View Post
Did you mention them after all (?)... (where is my head???)
Z-18 D1 TS Parameters http://www.sundownaudio.com/misc/201...%2018%20D1.JPG
Z-18 D2 TS Parameters http://www.sundownaudio.com/misc/201...%2018%20D2.JPG
Thanks, my bad again ! :-)

Appreciate your advice and explanations.
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