Stereo and Mono from Stereo source

MegatronUK · 13th December 2011, 06:41 PM

Hi,

I'm currently feeding a stereo line level signal to a 25w ST540 based Sparkfun stereo amplifier (running the main mid range drivers) and a 18w HA13118 based mono amp (powering a single bass driver).

At the moment I'm using a simple resister circuit to combine the left and right channels into a single mono feed for the mono amp, although this does work I do lose some volume and there is a noticeable drop in audio quality from the stereo circuit.

Is there a simple circuit or IC that will let me combine the stereo channels to mono but still feed the full, unaltered stereo signal to the stereo amplifier stage?

Basically, I need to run a pair of stereo speakers and a mono low frequency driver from a single stereo source.

Cheers,
John

johnyradio · 3rd February 2012, 04:34 AM

i'd like to know how to do this too.

would it be better to use a crossover based around an op-amp or transistor, to isolate the mono bass signal from the stereo signal?

here's one that might work:
monoXover 2-way pre-amp audio crossover

jr

DF96 · 3rd February 2012, 09:36 AM

What resisor values are you using? If too low they will add too much load to the system. Something in the region of 1k-10k will probably be OK.

Speedskater · 3rd February 2012, 02:04 PM

This is the Rane note on how to do it with resistors:
Why Not Wye?

I think that Rod Elliott has an active circuit.
DIY Audio Articles

johnyradio · 3rd February 2012, 03:42 PM

fantastic!

here's another method, referenced elsewhere on this forum. I'm not sure if this is considered active or passive, since it's not powered, and does not use any transistors or op-amps. It uses an inductor, resistors, and capacitors:
monoXover 2-way pre-amp audio crossover

love that wye article, tho i'm confused about the resistors going from hot to ground. i thought the resistors are supposed to be series?

DF96 · 3rd February 2012, 07:53 PM

I think the resistor to ground is just to maintain DC bias when nothing is plugged in. May reduce clicks.

13th December 2011, 06:41 PM	#1
MegatronUK diyAudio Member Join Date: Jan 2011 Location: Newcastle/Durham	Stereo and Mono from Stereo source Hi, I'm currently feeding a stereo line level signal to a 25w ST540 based Sparkfun stereo amplifier (running the main mid range drivers) and a 18w HA13118 based mono amp (powering a single bass driver). At the moment I'm using a simple resister circuit to combine the left and right channels into a single mono feed for the mono amp, although this does work I do lose some volume and there is a noticeable drop in audio quality from the stereo circuit. Is there a simple circuit or IC that will let me combine the stereo channels to mono but still feed the full, unaltered stereo signal to the stereo amplifier stage? Basically, I need to run a pair of stereo speakers and a mono low frequency driver from a single stereo source. Cheers, John

3rd February 2012, 02:04 PM	#4
Speedskater diyAudio Member Join Date: Sep 2002 Location: Lakewood, Ohio	This is the Rane note on how to do it with resistors: Why Not Wye? I think that Rod Elliott has an active circuit. DIY Audio Articles __________________ Kevin

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3rd February 2012, 04:34 AM	#2
johnyradio diyAudio Member Join Date: Sep 2011	i'd like to know how to do this too. would it be better to use a crossover based around an op-amp or transistor, to isolate the mono bass signal from the stereo signal? here's one that might work: monoXover 2-way pre-amp audio crossover jr

3rd February 2012, 09:36 AM	#3
DF96 diyAudio Member Join Date: May 2007	What resisor values are you using? If too low they will add too much load to the system. Something in the region of 1k-10k will probably be OK.

3rd February 2012, 03:42 PM	#5
johnyradio diyAudio Member Join Date: Sep 2011	fantastic! here's another method, referenced elsewhere on this forum. I'm not sure if this is considered active or passive, since it's not powered, and does not use any transistors or op-amps. It uses an inductor, resistors, and capacitors: monoXover 2-way pre-amp audio crossover love that wye article, tho i'm confused about the resistors going from hot to ground. i thought the resistors are supposed to be series?

3rd February 2012, 07:53 PM	#6
DF96 diyAudio Member Join Date: May 2007	I think the resistor to ground is just to maintain DC bias when nothing is plugged in. May reduce clicks.

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