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Old 16th October 2011, 08:19 PM   #11
Tytte71 is offline Tytte71  Norway
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Quote:
Originally Posted by peace brainerd View Post
For the time being my needs are similar to Spots. The plate amp I have on hand is a Foster 100w sub amp from the NHT sellout page. I'll live with it for a while and upgrade to a 500 w bash amp later. The existing oak cabinet I'm using has 4.2 cu ft available at present. So I can make it anything from .5 to 4.2 cu ft. I'd like to go sealed. In this case, and similar to what Spot is asking, if focusing on the Dayton offerings, which would be optimal for a small(ish) sealed box..... the 12 inch HO, the 12 inch HF, or the 12 Titanic? 98 percent music at moderate levels.
I don't know anything of the amp you are reffering to, but if it is the WF-100k then you have the option of tuning a bass boost function by changing some internal components (see the Excel sheet and FAQ on http://home.comcast.net/~jhidley/). You said 100W? the WF-100K can deliver 220W/8ohm 1%THD, so I feel I have missed on the amp type here Can you confirm?
If the sub amp is the limit it would be relevant to know the output power of your main amp and the main speaker sensitivity. No point in recommending a sub that looses the main speakers half way.
Another thing... with 4,5 cu. ft. available - why don't you want a driver (i.e. 15") that fully utlizes this volume - you could sell the complete package when you want to upgrade At 4,5 cu. ft. you can get a more efficient sub.
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Old 16th October 2011, 11:11 PM   #12
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Quote:
Originally Posted by peace brainerd View Post
For the time being my needs are similar to Spots. The plate amp I have on hand is a Foster 100w sub amp from the NHT sellout page. I'll live with it for a while and upgrade to a 500 w bash amp later. The existing oak cabinet I'm using has 4.2 cu ft available at present. So I can make it anything from .5 to 4.2 cu ft. I'd like to go sealed. In this case, and similar to what Spot is asking, if focusing on the Dayton offerings, which would be optimal for a small(ish) sealed box..... the 12 inch HO, the 12 inch HF, or the 12 Titanic? 98 percent music at moderate levels.
The pics tell the tale
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Old 16th October 2011, 11:35 PM   #13
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plug this one in....I know it is a car sub.....but they are tough as nails and sound amazing....and less than 100 bucks ea.

http://www.powerbassusa.com/l-124d-12-subwoofer
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Old 16th October 2011, 11:39 PM   #14
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ok.. be right back.

it looks just like the titanic transfer function chart, but... you need 8cf for a Qtc of.7 and can only use 60w and is 6db down at full tilt compared to the titanic.

Last edited by revboden; 16th October 2011 at 11:54 PM.
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Old 17th October 2011, 03:25 AM   #15
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Rev, I've yet to get acquainted with software modeling (in fact I'm going to start looking into it tonight... loooong past due). Can you interpret those graphs for me a little?

Quote:
You said 100W? the WF-100K can deliver 220W/8ohm 1%THD, so I feel I have missed on the amp type here Can you confirm?
I have two of these from the NHT sale. It's the WF-100K. From the description below it appears as if the 220w figure is for two bridged. This is from http://home.comcast.net/~jhidley/ about half way down the page. I looked into the directions for this and don't feel it's worth the bother. It's not a clean bridge since the function knobs of the bridged amp are not defeated and must be synced with the other amp. I do like the idea of being able to "tune" the amp, but will probably just leave it as is until I can afford a more powerful/flexible plate amp. I'll just run whatever sealed box I come up with with one of these.

Quote:
Foster WF-100K subwoofer plate amplifier

These amplifiers are no longer available

Foster subwoofer plate amplifier. 115W into 4ohms, 80W into 8ohms. 4th order (24dB/octave) low pass adjustable from 50-200Hz. 0-180 degree phase switch, RCA and speaker level inputs, volume control. Unit has a 3rd order (18dB/octave) high pass filter at 29Hz with a Q of 0.707 built into the subwoofer section. Can easily be modified for any Q and cutoff frequency that you want by changing R615, R617, R618, C607, C608 and C609. The amplifier also has a spectral tilt control that is adjusted to give about 10dB of shelving. It can be manually adjusted with a pot on the PCB. See response curves linked below. A drawing of the amplifier and schematic are both linked below. Two of these amplifiers can be bridged together to produce 220W into 8ohms. See the FAQ below for details of bridging and filter modifications.

This amplifier is available in two versions. Ver1 is externally switchable between 115/230VAC. If you want this version, clearly indicate so on your order. Ver2 has a modified HP filter to extend and flatten the bass response down to about 20Hz. See the pdf files below for the measured frequency response. This version is 115VAC only.

Last edited by peace brainerd; 17th October 2011 at 03:33 AM.
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Old 17th October 2011, 03:35 AM   #16
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Quote:
You said 100W? the WF-100K can deliver 220W/8ohm 1%THD, so I feel I have missed on the amp type here Can you confirm?
I have two of these from the NHT sale. It's the WF-100K. From the description below it appears as if the 220w figure is for two bridged. I looked into the directions for this and don't feel it's worth the bother. It's not a clean bridge since the function knobs of the bridged amp are not defeated and must be synced with the other amp. I do like the idea of being able to "tune" the amp, but will probably just leave it as is until I can afford a more powerful/flexible plate amp. I'll just run whatever sealed box I come up with with one of these.

Quote:
Foster WF-100K subwoofer plate amplifier

These amplifiers are no longer available

Foster subwoofer plate amplifier. 115W into 4ohms, 80W into 8ohms. 4th order (24dB/octave) low pass adjustable from 50-200Hz. 0-180 degree phase switch, RCA and speaker level inputs, volume control. Unit has a 3rd order (18dB/octave) high pass filter at 29Hz with a Q of 0.707 built into the subwoofer section. Can easily be modified for any Q and cutoff frequency that you want by changing R615, R617, R618, C607, C608 and C609. The amplifier also has a spectral tilt control that is adjusted to give about 10dB of shelving. It can be manually adjusted with a pot on the PCB. See response curves linked below. A drawing of the amplifier and schematic are both linked below. Two of these amplifiers can be bridged together to produce 220W into 8ohms. See the FAQ below for details of bridging and filter modifications.

This amplifier is available in two versions. Ver1 is externally switchable between 115/230VAC. If you want this version, clearly indicate so on your order. Ver2 has a modified HP filter to extend and flatten the bass response down to about 20Hz. See the pdf files below for the measured frequency response. This version is 115VAC only.
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Old 17th October 2011, 11:26 PM   #17
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Quote:
Originally Posted by peace brainerd View Post
Rev, I've yet to get acquainted with software modeling (in fact I'm going to start looking into it tonight... loooong past due). Can you interpret those graphs for me a little?
I'll try... They are a general comparison of the three drivers in sealed boxes that yield a Qtc of ~.57, that is a box volume that is critically damped (read this: Q factor and damping Q factor - Wikipedia, the free encyclopedia )

The first chart (on the left) tells you how much power you can use in this alignment with each driver to reach Xmax.

The second chart shows SPL at Xmax or maximum output for each frequency.

The third is Transfer Function, which shows each drivers efficiency at producing sound at each frequency relative to the other drivers. It's much like the SPL chart in shape but has -3db lines on the graph.

any other questions, feel free to ask.

Last edited by revboden; 17th October 2011 at 11:28 PM.
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Old 17th October 2011, 11:29 PM   #18
Tytte71 is offline Tytte71  Norway
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Quote:
Originally Posted by peace brainerd View Post
I have two of these from the NHT sale. It's the WF-100K. From the description below it appears as if the 220w figure is for two bridged. I looked into the directions for this and don't feel it's worth the bother. It's not a clean bridge since the function knobs of the bridged amp are not defeated and must be synced with the other amp. I do like the idea of being able to "tune" the amp, but will probably just leave it as is until I can afford a more powerful/flexible plate amp. I'll just run whatever sealed box I come up with with one of these.
Oh... I see that.
I will repeat that the sealed cabinet is a very inefficient solution and therefore requires massive amount of power to deliver high sound pressures. In addition, when designing subs it is recommended to include a 6-10dB headroom within the drivers linear stroke.
Then you will see that with a 110W@4ohm amp the maximum (design) mean sound pressure is very limited unless you make a more efficient design than a sealed cabinet.
My recommendation to you would be to buy a Peerless XXLS or maybe a Eminence LAB12 and use it in your 4,5 cu.ft. cabinet as BR. Tune the port to 20Hz (12x610mm). With regards to impulse response and group delay this would leave you a system that fully competes with the qalities of a sealed cabinet. The 4ohm version should be pretty versatile for your wishes of using a sealed cabinet. You could then later, when money allows for it, rebuild the sub to a sealed enclosure with a more powerfull amp.

Here are a few maximum output figures when feeding the XXLS with 110W (you should subtract 6dB for baffle step diffraction and add room gain to the dB numbers below):

frq______BR (120litre), Sealed (45litre)
20Hz____ 103,9______ 95,5
25Hz____ 105,8______ 98,1
30Hz____ 106,2______ 100,5
35Hz____ 106,4______ 102,4
40Hz____ 107,1______ 103,7
50Hz____ 107,1______ 105,4
100Hz___ 107,7______ 107,7

In both cases the driver moves within linear stroke range down to 20Hz.
Port resonance at 250Hz.

Last edited by Tytte71; 17th October 2011 at 11:34 PM.
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Old 20th October 2011, 06:14 PM   #19
Asdonk is offline Asdonk  Netherlands
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Which model xxls12 are you using ?

I have both the 830845 and 835017 models

830845 in 43 l with Linkzwitz Transform

830517 in 62 l bassreflex .... > XTZ 99w12.18 Ice
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Old 21st October 2011, 02:58 AM   #20
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The XXLS is 247 dollars.

Every time I reshuffle the deck to include a more expensive driver I do the math and look at the Rythmikaudio servo kit with DS1200 black cone sealed 2 cu ft with A370PEQ servo amp for 560 bucks and start thinking again.

Or even the Creative Sound - Product Details
12 inch kit with Bash 300 amp for 379 dollars.

I don't know.. with the RSS drivers available for one hundred dollars less than the XXLS, what gives the XXLS the edge over the RSS 12 HF or HO?

Dammitall.. I wish this doubt was never sown concerning the HSS 12 HF's possibility for cone distortion/noise at high pressure. It didn't do much to help my analysis paralysis.

Last edited by peace brainerd; 21st October 2011 at 03:06 AM.
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