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Old 29th January 2015, 11:10 AM   #1
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Default 15" plenum ppsl

I'm getting ready to make a new subwoofer and reading about the ppsl decided to give it a go.

I could get my hands on some 15" neo drivers really cheap a while a go so I'm going to be using those. They where meant as replacement drivers for the sp15 system from soundprojects. specs: http://www.soundprojects.com/f/11702417977970 or http://www.soundprojects.com/f/13244791575400

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

I kindly asked the soundprojects guys and a reseller for the TS parameters but (as expected) didn't get an answer so I'll be measuring them myself. I have tried to do this with a multimeter for my previous build but wasn't really satisfied with how it went and I have some doubts about the accuracy of the multimeter at different frequencies.

Dual opposed Shiva sub with inuke1000dsp

I read about the woofer tester and others but it isn't very clear to me which is the one to get and where to get it in Europe.

I have the following design in mind:

Click the image to open in full size.

Click the image to open in full size.

It allows me to build the plenum first and measure the drivers as 1 unit inside the plenum. The plenum will go in the middle of the box. The drivers are 15cm tall, plenum is 18cm wide about 46cm high and deep. The sub will be about 0.5 by 0.5 by X meters. The total width, vented or sealed is to be determined after measuring TS. I assume the connecting space between the two sides behind the plenum is sufficient to allow for small differences in volume without causing problems.

So, anyone recognize the driver?

Which measuring tool do I get?

Is the space behind the plenum sufficient to connect the two halves without causing problems?

Last edited by Zonneschimmel; 29th January 2015 at 11:13 AM. Reason: clarification
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Old 29th January 2015, 08:35 PM   #2
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95% sure that's a Beyma driver. Take as many pictures as you can and e-mail them.
Its kinda like a 15G450N. Could be an earlier version.

Chris
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Old 30th January 2015, 12:12 PM   #3
xrk971 is online now xrk971  United States
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You can measure TS with REW and a 100ohm resistor and some cables and alligator clips. You will need a DMM which you have and a gram scale and some mass to measure Vas. Works well if you have a stereo line in sound card.

Or spend $100 plus shipping from US for the excellent DATS tool from Dayton Audio via Parts Express. Very accurate and super easy to use.
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Old 30th January 2015, 12:24 PM   #4
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@ chris661: pics incoming

Quote:
Originally Posted by xrk971 View Post
You can measure TS with REW and a 100ohm resistor and some cables and alligator clips. You will need a DMM which you have and a gram scale and some mass to measure Vas. Works well if you have a stereo line in sound card.

Or spend $100 plus shipping from US for the excellent DATS tool from Dayton Audio via Parts Express. Very accurate and super easy to use.
Measuring with REW sounds a lot like what i did with an audio card and pc sine generator manually, only a bit more automated and the calculations are done for you. I don't have difficulties doing the calculations, I'm doubting the multimeter measurement (I borrowed one before) for a big part of the range I only had 1 significant digit. If you go looking for a multimeter which specifies accuracy from 10-20000HZ and preferably has multiple significant digits in the measuring range, prices become very high very quickly and since I'll only be using it for speakers might as well buy an easier tool for that.

I'll take a look at the DATS
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Old 30th January 2015, 01:08 PM   #5
xrk971 is online now xrk971  United States
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Quote:
Originally Posted by Zonneschimmel View Post
@ chris661: pics incoming



Measuring with REW sounds a lot like what i did with an audio card and pc sine generator manually, only a bit more automated and the calculations are done for you. I don't have difficulties doing the calculations, I'm doubting the multimeter measurement (I borrowed one before) for a big part of the range I only had 1 significant digit. If you go looking for a multimeter which specifies accuracy from 10-20000HZ and preferably has multiple significant digits in the measuring range, prices become very high very quickly and since I'll only be using it for speakers might as well buy an easier tool for that.

I'll take a look at the DATS
The multimeter is used to measure one value of Re. The rest is done by REW in the sound card.
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Old 30th January 2015, 03:25 PM   #6
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Originally Posted by xrk971 View Post
The multimeter is used to measure one value of Re. The rest is done by REW in the sound card.
Cool, I'll look into it.
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Old 31st January 2015, 08:31 AM   #7
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What is the open area of the triangles?

It may not be enough for the Sd of the driver.
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Old 31st January 2015, 11:24 AM   #8
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What is the open area of the triangles?

It may not be enough for the Sd of the driver.
The triangle sides are 19cm, surface area of 1 triangle is 180cm².

The depth of the triangle is 22cm so 1 triangle volume is ~4000cm³.


I could make the B side a bit wider then the A side to compensate for the decreased volume from the driver.

Click the image to open in full size.
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Old 31st January 2015, 02:12 PM   #9
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Hey, sorry if I didn't make it clear, but e-mail the pictures to Beyma. I'm sure they'll be able to help you.
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Old 1st February 2015, 01:03 PM   #10
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I hooked up the drivers to an amp to loosen the suspension with some brown noise but one driver stops after 3 to 30 seconds depending on volume (faster at higher volume). I'm using a NAD 356bee (80wpc) so I'm not pushing the drivers far. I changed all the wiring from the amp to the drivers which makes no difference.

I think there might be a bad connection or short from the driver lead to the coil. Is there an easy way to fix this or is this something that is better left to professionals?
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