Hello !!
What do you thing of this circuit?
Cut-off frequency of 150hz between the low register box and the satelite.
It's good or not??
Thanks
What do you thing of this circuit?
An externally hosted image should be here but it was not working when we last tested it.
Cut-off frequency of 150hz between the low register box and the satelite.
It's good or not??
Thanks
Hi,
Kevin is almost right using the inverting opamp as the adder with the two 8k1 feeding the virtual earth.
Now, instead of using the 20k pot after the adder, which will alter the source impedance of the following stage, take the output pot back to the virtual earth and use it as a variable gain/attenuation feedback resistor. This maintains a low output impedance which the next filter stage needs to maintain the Linkwitz Reilly crossover slopes.
I would change to a 10k pot between output and inverting input to reduce the gain in the bass filter route, or increase the 8k1 to 16k or even 20k.
The bass speaker must be connected out of phase with the trebles to correct for the inverting stage of the adding/summing opamp.
Kevin is almost right using the inverting opamp as the adder with the two 8k1 feeding the virtual earth.
Now, instead of using the 20k pot after the adder, which will alter the source impedance of the following stage, take the output pot back to the virtual earth and use it as a variable gain/attenuation feedback resistor. This maintains a low output impedance which the next filter stage needs to maintain the Linkwitz Reilly crossover slopes.
I would change to a 10k pot between output and inverting input to reduce the gain in the bass filter route, or increase the 8k1 to 16k or even 20k.
The bass speaker must be connected out of phase with the trebles to correct for the inverting stage of the adding/summing opamp.
simpler solution:
move the LF pot&buffer to the output of either of the low pass filter section outputs
split the lowpass filter's 1st section input 7.5K into two 15K, one to each of L/R buffered inputs - replacing/eliminating the 8K resistors
as for the design of such a crossover I'd look at Linkwitz' site:
http://www.linkwitzlab.com/Pluto/subwoofer.htm
shows an example of crossing over to a sub (actually 2 subs), with eq of the sub response
move the LF pot&buffer to the output of either of the low pass filter section outputs
split the lowpass filter's 1st section input 7.5K into two 15K, one to each of L/R buffered inputs - replacing/eliminating the 8K resistors
as for the design of such a crossover I'd look at Linkwitz' site:
http://www.linkwitzlab.com/Pluto/subwoofer.htm
shows an example of crossing over to a sub (actually 2 subs), with eq of the sub response
I'm confused. Not a rare event. But, if this is for a summed central subwoofer, it seems like level controls on the L and R are not what you need. They can come through as is (unless the gain is high), whereas it's the sub that needs the level control. I built one very similar to this, with one level control on the front panel, and it worked great.
edit- I'd also bring up that it's easiest to get good sound if your satellites are *not* ported, lest there be odd phase problems around the crossover point. IMO, if they're ported it's a good idea to experiment with stuffing the port. I just picked up a small pair of KEF "Q" speakers for the TV, and they actually come with foam plugs, but little explanation. My guess is when one adds a subwoofer, they'll come in handy.
edit- I'd also bring up that it's easiest to get good sound if your satellites are *not* ported, lest there be odd phase problems around the crossover point. IMO, if they're ported it's a good idea to experiment with stuffing the port. I just picked up a small pair of KEF "Q" speakers for the TV, and they actually come with foam plugs, but little explanation. My guess is when one adds a subwoofer, they'll come in handy.
Here satelites :
http://www.jamo.com/Default.aspx?ID=6187&M=Shop&PID=17681&ProductID=17639
and the boomer:
I want to build a system triphonic.
http://www.jamo.com/Default.aspx?ID=6187&M=Shop&PID=17681&ProductID=17639
An externally hosted image should be here but it was not working when we last tested it.
and the boomer:
An externally hosted image should be here but it was not working when we last tested it.
I want to build a system triphonic.
Gain=20*log(r2/r1)
if r2<r1 then result is negative.
To avoid Kevin's worry of parasitic capacitance on the inverting input, you can replace the pot with a fixed resistor once you have the levels matched. But, look at any inverting attenuator and they adopt a wide range of adjusting resistors.
if r2<r1 then result is negative.
To avoid Kevin's worry of parasitic capacitance on the inverting input, you can replace the pot with a fixed resistor once you have the levels matched. But, look at any inverting attenuator and they adopt a wide range of adjusting resistors.
An externally hosted image should be here but it was not working when we last tested it.
After clacul here the final diagram. I will use a potentiometer to be welded onto C.I for the RV2.
Does that seem to you corect?
Hi,
I think RV2 is too big.
47k/10k gives +13.4db.
each output is mono when the signal is low frequency so the effective gain from adding both channels is 6db higher i.e. +19.4db.
or 47k/(10k/2)=+19.4db
Reduce the pot to 20k (+12db) or maybe as low as 10k (+6db).
0.47uF for DC blocking caps is too low. It will remove some of the sub-bass signal that your summed channel is trying to pass.
2u2F would better suit the 50k input pot.
I think RV2 is too big.
47k/10k gives +13.4db.
each output is mono when the signal is low frequency so the effective gain from adding both channels is 6db higher i.e. +19.4db.
or 47k/(10k/2)=+19.4db
Reduce the pot to 20k (+12db) or maybe as low as 10k (+6db).
0.47uF for DC blocking caps is too low. It will remove some of the sub-bass signal that your summed channel is trying to pass.
2u2F would better suit the 50k input pot.
Like this?
These new values give a beach of adjustments of +6db to -20db.
The speaker JAMO make 86db output and the sub-woofer make 87db.
According to my style of listening I will be able to adapt the level of the boomer by raport to the JAMO speakers.
An externally hosted image should be here but it was not working when we last tested it.
These new values give a beach of adjustments of +6db to -20db.
The speaker JAMO make 86db output and the sub-woofer make 87db.
According to my style of listening I will be able to adapt the level of the boomer by raport to the JAMO speakers.
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