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Old 8th January 2008, 05:53 AM   #1
peter_m is offline peter_m  Canada
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Default Pluto sub - Peerles 830668

http://www.linkwitzlab.com/Pluto/subwoofer.htm
http://www.linkwitzlab.com/filters.htm#9

This design can use an inexpensive 10" sub in a relatively small enclosure (15L) with the use of an electronic EQ. Anyone have experience with this design? Any counter indications to use it with a pair of Zaph's B3S?

Peter

EDIT: I have the C and R values but I am not sure where to put them on this diagram... Any help?
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Old 8th January 2008, 06:26 AM   #2
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Default More info

http://sound.westhost.com/project71.htm

http://sound.westhost.com/project48.htm

http://sound.westhost.com/linkwitz-transform.htm

Ping for richie00boy

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Old 8th January 2008, 06:45 AM   #3
peter_m is offline peter_m  Canada
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I'll see you on the dark side my friend. Great Links!
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Old 10th January 2008, 05:21 AM   #4
peter_m is offline peter_m  Canada
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Hum..... for the 830668 values... should I just use what Linkwitz calculated (f0 = 74.3 Hz & Q0 = 1.57) ?

Or should I use the Peerless data for Fs = 33Hz, Qts = 0.51, Vas = 69L to calculate my own f0 = 80.3Hz & Q0 = 1.24 ????


What to do? Does anyone know if this will work for a sub x-over of 150 hz?

Peter
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Old 12th January 2008, 09:12 PM   #5
gfiandy is offline gfiandy  United Kingdom
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I am a little confused by what you are asking however I have tryed to answer what I think your question was.

The Linkwitz transform should be used to correct the LF part of the bass response it has little or no effect on the crossover to the main speakers.

You should calculate the characterisitcs of your drive unit in the box you intend to use it in and then decide on what response you would like to have. Take into account that if you try to push the response too low you will either over extend the drive unit mechanically and damage the surround or electrically and burn out the voice coil. Use this data to calculate the required transform components.

The drive unit will easly output upto 150Hz so you can crossover there if you want to. However for crossover frequency of above about 100Hz you need to keep the sub very near to the main speakers as you ear can start to localise that the LF sound is not comming from the same place as the mid/hf.

Regards,
Andrew
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Old 12th January 2008, 10:55 PM   #6
peter_m is offline peter_m  Canada
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Maybe I was not clear with my questions. I apologize but you understood right, it was 2 parts.

1) I wanted to build the exact same enclosure and use the same driver as SL used in this page: http://www.linkwitzlab.com/Pluto/subwoofer.htm This would keep it simple for me by following a tried and tested design. Also found an excel spreadsheet that calculates Fo & Qo based on Fs, Qts & Vas from here: http://sound.westhost.com/linkwitz-transform.htm and decided to test SL's numbers. When I plugged in the data from the Peerless website, the calculated Fo and Qo did not match SL's measured Fo and Qo... Should I use the data from Linkwitz's measurements or the data generated by the spreadsheet? That was my original question but I have been shown how to make my own measurement with this: http://www.linkwitzlab.com/images/graphics/f0Q0.gif and will do so when I receive the driver. Apparently I am not the only one to have noticed discrepancies as someone else is the Linkwitz forum made his own measurements and they don't match either.


2) 150hz is the x-over frequency to integrate the sub to my satellites drivers. Great to know the sub will go that high. I know I will have to centre it between the satellites for best results. Thanks

Regards,

Peter
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Old 13th January 2008, 01:18 PM   #7
gfiandy is offline gfiandy  United Kingdom
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Thanks for your clarification. I would agree that it is best to make your own measurements as drive units characteristics do vary.

I recomend running the drive unit in before taking any measurements as they can change quite alot as the suspension sofens up a bit.

Regards,
Andrew
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Old 13th January 2008, 01:41 PM   #8
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Your own measurements would be best, but if you don't have them I would use Linkwitz's values as he has nothing to hide.

Regarding where to put the R and C values if you just building the EQ part, look between TP2 and TP3 on the schematic on the Pluto page, it's all there already.
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Old 13th January 2008, 02:56 PM   #9
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Peter,

I have been building the same subwoofer you are. I was also wondering if I would use the parameters on Linkwitz's website, but after building my enclosure and making measurements I found that mine differ very little. I use somewhat different component values for the filtering - not shure what @ the moment since it is on breadboard on top of my amp about 2,3 meters above the floor - but if you want I could look it up for you.

Btw, I tried how much the subwoofer could take and I was only able to overdrive the unit when playing some testtrack with a helicopter @ 12 Hz making the windows throughout the house ring.

Good luck on you build!

Martin
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Old 13th January 2008, 03:56 PM   #10
peter_m is offline peter_m  Canada
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Wow Thanks guys! For a while I was starting to get nervous about the sub. I have already ordered the driver and was beginning to think it was an obscure and not so popular design... confidence is restored

How long till the driver breaks in and it's specs stop changing? Can I just use a 20hz signal to give it a good workout while I am out of the house?

Also, since I am letting to sub go as high as 150hz, should I have it forward firing like a woofer, or should I keep it in a down firing position?

Glad to know I will be able to shake some windows Will post my results when enclosure is built and everything is up and running.

Peter
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