Repurpose a Logitech subwoofer driver

trumper · 25th November 2020, 06:34 PM

The Logitech z623 system came to an end when the control pod switches started to not work properly. Tried to fix but nope.......crushed more surface mount components than able to replace.

Sooooo... the subwoofer was more than my listening room could use (at reasonable levels) and there is a bad room resonance around 60hz.

So I removed the sub driver from the cabinet and set about to build a replacement cabinet with new class D amplification.

Progress reports to follow.....

trumper · 27th November 2020, 09:56 PM

The goal is augment my mMar-Kel70s. I will be happy with 40hz which the original sub could do.

With no parameters for the driver, I decided to use the basic volume of the original box - about 17.4 litres or 0.614 cu ft. I also wanted to use a slot port instead of the original round port.
I found a port calculator image on this forum but can't remember which thread so I will post the image here.

After making an excel sheet to do the math, I have drawn the plan.

waxx · 27th November 2020, 10:22 PM

It's not that simple, as there are no published specs of the driver you (or someone) need to measure it to get the specs. Only from the specs you can determine the right cabinet for it. Search someone who can measure the driver (or if you have Dats or Clio or so, do it yourself) and start from there from scratch. Now you're shooting in the dark.

REDSKIN · 27th November 2020, 11:35 PM

Why do you need ts parameters if you're making a box the same size as the old one?

trumper · 28th November 2020, 10:06 AM

I know that this method is not ideal without driver specs but I figure that the original box was designed for the driver so we shall see how close this "dead reckoning" approach gets me. If nothing else, it is fun to make the excel formulas and then play with the variables to see the calculated outcome....

The original box was 1/2" mdf and this one is 18mm baltic birch.

waxx · 28th November 2020, 10:36 AM

Well, a round port reacts different than a slot, so it needs an other length than a slot. What will hapen is that the tuning of the port is not right. Box size could also not be ideal as commercial speakers are more build on size and looks than on specs, especially this kind of speakers. But you could try off course...

trumper · 1st January 2021, 07:35 PM

Well it is together....but there is no bass. Driver isn't moving with 50hz signal and barely moving with 60hz.

I suspect the amp needs some modding as per John Audio Tech (TPA3116 audio amplifer board test, review & mod - YouTube).

Surtsey · 2nd January 2021, 12:22 PM

By sealing the port do you get more or less bass?

trumper · 9th January 2021, 04:06 PM

Finally got around to sealing the port today. No real difference.
However I moved the sub and i can hear the 50 - 40hz tones (although reduced level).

I will try bypassing the amp's 5532 preamp with a capacitor once i source one.

25th November 2020, 06:34 PM	#1
trumper diyAudio Member Join Date: Oct 2011 Location: Eastern Ontario	Repurpose a Logitech subwoofer driver The Logitech z623 system came to an end when the control pod switches started to not work properly. Tried to fix but nope.......crushed more surface mount components than able to replace. Sooooo... the subwoofer was more than my listening room could use (at reasonable levels) and there is a bad room resonance around 60hz. So I removed the sub driver from the cabinet and set about to build a replacement cabinet with new class D amplification. Progress reports to follow.....

27th November 2020, 11:35 PM	#4
REDSKIN diyAudio Member Join Date: Jan 2004 Location: LONDON	Why do you need ts parameters if you're making a box the same size as the old one? __________________ He shoots. He scores!

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27th November 2020, 10:22 PM	#3
waxx diyAudio Member Join Date: Apr 2014 Location: Wodecq, Belgium	It's not that simple, as there are no published specs of the driver you (or someone) need to measure it to get the specs. Only from the specs you can determine the right cabinet for it. Search someone who can measure the driver (or if you have Dats or Clio or so, do it yourself) and start from there from scratch. Now you're shooting in the dark.

28th November 2020, 10:36 AM	#6
waxx diyAudio Member Join Date: Apr 2014 Location: Wodecq, Belgium	Well, a round port reacts different than a slot, so it needs an other length than a slot. What will hapen is that the tuning of the port is not right. Box size could also not be ideal as commercial speakers are more build on size and looks than on specs, especially this kind of speakers. But you could try off course...

2nd January 2021, 12:22 PM	#8
Surtsey diyAudio Member Join Date: Sep 2019	By sealing the port do you get more or less bass?

9th January 2021, 04:06 PM	#9
trumper diyAudio Member Join Date: Oct 2011 Location: Eastern Ontario	Finally got around to sealing the port today. No real difference. However I moved the sub and i can hear the 50 - 40hz tones (although reduced level). I will try bypassing the amp's 5532 preamp with a capacitor once i source one.