Lowering a sub's volume by adding a resistor to the cable...

robinmiller · 6th January 2006, 10:21 PM

This is a real hack, but i was hoping to get some advice about it:

I have a Logitech Z3 speaker system. It's a pretty cheap system but sounds adequate, except for one thing. The subwoofer volume is way too loud, even with the sub level knob set to the minimum.

I opened up the sub cabinet (which also houses all the electronics), and found what i think are the two wires travelling to the sub itself (which is hidden in a different chamber in the cabinet).

Can i snip one of these wires and place a resistor in line, to cut the sub's volume a bit? The sub is rated at 23W RMS. Would i need some massive resistor to handle 23W? Also, how many Ohms would be suitable?

Thanks for any advice!

-robin

Coolin · 7th January 2006, 12:54 PM

Its not a very good solution and will heat up the resistor quite bit.
So if you do, you will need a fairly big one so it doesnt get too hot. Also watch out where you put it because it might melt something its touching....

A better way would be to try to put a risistor in series with the sub volume control to get a little more leeway on that range....

Might be hard to get too ?

robinmiller · 7th January 2006, 03:29 PM

thanks. Yeah, the volume control was a lot harder to get to, but last night i gave it a shot. The weird thing was that it seemed to be a dual gang volume control, and the resistances weren't the same on the two gangs.

Anyhow, not knowing which was which, i cut the traces leading away from the pot's two output pins, an bridged each with a 4.7k resistor.

It was just a shot in the dark, but the sub does seem to be tamed quite a bit now.

Any ideas why the dual gang?

I did notice that the mids seem really weak now.. could that pot have controlled both the sub's output and the mid range from the speakers?

The other interesting thing i noticed was that when i opened up this Logitech sub, all the circuits were marked 'Labtec'.. heh

Coolin · 7th January 2006, 07:15 PM

The lower mids probably also come from the sub so you lost those as well. You could try placing a capasitor in series instead of the resistor to retain the mids while still reducing the lows. Youl have to play with the value though.
If you look carefully you might even spot how they made the lowpass and adjust components there.

The stereo pot might be from the L+R chanels to be combined before the amp.

6th January 2006, 10:21 PM	#1
robinmiller diyAudio Member Join Date: Jan 2006 Location: NYC	Lowering a sub's volume by adding a resistor to the cable... This is a real hack, but i was hoping to get some advice about it: I have a Logitech Z3 speaker system. It's a pretty cheap system but sounds adequate, except for one thing. The subwoofer volume is way too loud, even with the sub level knob set to the minimum. I opened up the sub cabinet (which also houses all the electronics), and found what i think are the two wires travelling to the sub itself (which is hidden in a different chamber in the cabinet). Can i snip one of these wires and place a resistor in line, to cut the sub's volume a bit? The sub is rated at 23W RMS. Would i need some massive resistor to handle 23W? Also, how many Ohms would be suitable? Thanks for any advice! -robin

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7th January 2006, 12:54 PM	#2
Coolin diyAudio Member Join Date: Apr 2003 Location: Holland	Its not a very good solution and will heat up the resistor quite bit. So if you do, you will need a fairly big one so it doesnt get too hot. Also watch out where you put it because it might melt something its touching.... A better way would be to try to put a risistor in series with the sub volume control to get a little more leeway on that range.... Might be hard to get too ?

7th January 2006, 03:29 PM	#3
robinmiller diyAudio Member Join Date: Jan 2006 Location: NYC	thanks. Yeah, the volume control was a lot harder to get to, but last night i gave it a shot. The weird thing was that it seemed to be a dual gang volume control, and the resistances weren't the same on the two gangs. Anyhow, not knowing which was which, i cut the traces leading away from the pot's two output pins, an bridged each with a 4.7k resistor. It was just a shot in the dark, but the sub does seem to be tamed quite a bit now. Any ideas why the dual gang? I did notice that the mids seem really weak now.. could that pot have controlled both the sub's output and the mid range from the speakers? The other interesting thing i noticed was that when i opened up this Logitech sub, all the circuits were marked 'Labtec'.. heh

7th January 2006, 07:15 PM	#4
Coolin diyAudio Member Join Date: Apr 2003 Location: Holland	The lower mids probably also come from the sub so you lost those as well. You could try placing a capasitor in series instead of the resistor to retain the mids while still reducing the lows. Youl have to play with the value though. If you look carefully you might even spot how they made the lowpass and adjust components there. The stereo pot might be from the L+R chanels to be combined before the amp.