stereo to mono for sub

[arjunm009]

Hello,
Kindly assist me in explaining the values chosen of the resistor to convert any stereo output to mono.

I have seen many stereo to mono converter circuits online. All had different resistor values for their respective left/right channels and then summed and output fed to a mono amp.

Is there any particular formula to calculate the values.

FYR, the sub chosen is Tang Band W2-2040S, coupled with a 3.5inch Peerless 830878 passive and for upper range, 2 fullrange Visaton FRS7-4. This will become a 2.1 channel unit.

Thanks.

 

[bjorno]

Hello,
Kindly assist me in explaining the values chosen of the resistor to convert any stereo output to mono.

I have seen many stereo to mono converter circuits online. All had different resistor values for their respective left/right channels and then summed and output fed to a mono amp.

Is there any particular formula to calculate the values.

FYR, the sub chosen is Tang Band W2-2040S and for upper range, 2 fullrange Visaton FRS7-4. This will become a 2.1 channel unit.

Thanks.

Hi arjunm009,

Here is what I would do:

b🙂

 

[sreten]

Hi,

That TB will have an impossible time keeping up with the
other two drivers, its senstivity is appalling compared
to them, not surprising when a subs Vas is lower
that the mid/trebles it is being matched to.

Its all wrong and you need a rethink.

rgds, sreten.

The resistor values are not critical, about 10K.

 

[bjorno]

Hi arjunm009,

Here is what I would do:

b🙂

FYI:
Max input Power to Tang Band W2-2040S in my design is ~30W Rms==>~ 94 dB SPL Pass-band in 1xPi .
For the Visaton FRS7-4: 8W Rms==> ~93 dB SPL in the Passband; 2xPi.


b🙂

 

[Davey]

Hello,
Kindly assist me in explaining the values chosen of the resistor to convert any stereo output to mono.

I have seen many stereo to mono converter circuits online. All had different resistor values for their respective left/right channels and then summed and output fed to a mono amp.

Is there any particular formula to calculate the values.

FYR, the sub chosen is Tang Band W2-2040S and for upper range, 2 fullrange Visaton FRS7-4. This will become a 2.1 channel unit.

Thanks.

I assume you plan to do this at line-level (before the amplifiers?)

There isn't any particular formula or value to use.
Generally, two resistors of about 2kohms each will give you proper summing with minimal insertion loss and minimal left/right separation loss to your main amplifier if it's hooked to the outputs also.

Sometimes a source will have fairly high output resistances and you can simply "Y" the outputs together.

It would be nice if you knew the output resistance of your preamp and the input resistances of both amplifiers. You could make a better estimation then.

Dave.

 

[arjunm009]

The amp for the sub needs a rethink. I understand. I was primarily thinking of powering the full range with 3W or 2W and the sub with something b/w 5W to 10W(such ICs only need 5V to operate). It can also be coupled with a low pass shelving boost, right?

The main choice of going with that sub was because of its size. It is small and fits the end application, i.e., portable unit. I forgot to state one more thing that a passive radiator, Peerless 830878, would also be used in conjunction with the active one.

I am only looking for a good decent low end, somewhere from 70Hz. Using the sub and passive in 60inch3 would tune it to 55Hz, I believe. For me that was great. So I went with this combo.

But definitely I am open to any other suggestion. I dont prefer using a tweeter. Lots of complexities with the circuit. i looking to build this on a budget.

Thank you.

 

[arjunm009]

Hey
I found this link from Maxim Integrated - Reference Design for a Class D, 2.1-Channel, Audio Amplifier for an MP3 Docking Station - Reference Schematic - Maxim

In the power stage section it i written that -

After the input stage, the left and right signals are then summed using U5-B to create the monosubwoofer channel. R303 is used to set the subwoofer channel gain at the summing amp.

There is also mention of stabilizing the Q, Sallen-Key filter and other high-level stuff. What is that all about.

 

[sreten]

Hi,

There are better bigger options than the TB in the sort
of volume you'd need to tune the Peerless PR to a bass
alignment. bigger Vd and more senstivity to boot.

rgds, sreten.