Yes, but it may mean that the anti turn off thump feature may not work as well. Try it and if there is no bothersome thump on turn off you are good.
If you have lots of 47uF caps out them in series back to back (Positve to positive etc). That will halve the cap value to 23.5uF.
If you have lots of 47uF caps out them in series back to back (Positve to positive etc). That will halve the cap value to 23.5uF.
My board arrived in the mail yesterday, now have a question.
Going to use in a class A Sissysit amp, but to drive very power hungry headphones.
Wondering if and how to adjust the DC offset trip point to something lower than 1.5V?
Was thinking something around 0.5 or 1.0 VDC. Probably closer to 0.5.
I can change out SM resistors, figure that will be required. Need to place a Mouser order, so I can buy whatever I need with the order.
TIA
Randy
Going to use in a class A Sissysit amp, but to drive very power hungry headphones.
Wondering if and how to adjust the DC offset trip point to something lower than 1.5V?
Was thinking something around 0.5 or 1.0 VDC. Probably closer to 0.5.
I can change out SM resistors, figure that will be required. Need to place a Mouser order, so I can buy whatever I need with the order.
TIA
Randy
I have a SSR headphone protection circuit made just for headphones. It’s pretty easy to assemble if you can do basic SMT parts.
https://www.etsy.com/listing/971912371/ssr-headphone-protection-pcbs?click_key=01201391821312372668eff65fb7242f997d9a97:971912371&click_sum=159bf2c4&ref=shop_home_active_12
For the speaker SSR threshold level to be set to a lower value - will require some calculations. Let me ask Jhofland if he has suggested values. What would you like the threshold to be? 1.5v should not destroy a headphone. You might want to keep it to allow deep transient bass kick drums.
The threshold is controlled by an RC circuit R102 and C102. When DC charges this up there is a time constant and this powers an LED in an optoisolator. The output of the optoisolator feeds a comparator. R104 is a 200k resistor that sets the trip point of the comparator. One could make this value larger to force the reference voltage divider to a lower value. Something like 200k to 300k might make it trip at a lower voltage. Depends on where you want it. Changing R102 to a smaller value will let the RC charge up faster for a quicker response.
https://www.etsy.com/listing/971912371/ssr-headphone-protection-pcbs?click_key=01201391821312372668eff65fb7242f997d9a97:971912371&click_sum=159bf2c4&ref=shop_home_active_12
For the speaker SSR threshold level to be set to a lower value - will require some calculations. Let me ask Jhofland if he has suggested values. What would you like the threshold to be? 1.5v should not destroy a headphone. You might want to keep it to allow deep transient bass kick drums.
The threshold is controlled by an RC circuit R102 and C102. When DC charges this up there is a time constant and this powers an LED in an optoisolator. The output of the optoisolator feeds a comparator. R104 is a 200k resistor that sets the trip point of the comparator. One could make this value larger to force the reference voltage divider to a lower value. Something like 200k to 300k might make it trip at a lower voltage. Depends on where you want it. Changing R102 to a smaller value will let the RC charge up faster for a quicker response.
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Thanks. I have one of you headphone protection boards too, but it has a common ground and I didn't want to tie the output lows together at your board (even if they are ground).I have a SSR headphone protection circuit made just for headphones. It’s pretty easy to assemble if you can do basic SMT parts.
https://www.etsy.com/listing/971912371/ssr-headphone-protection-pcbs?click_key=01201391821312372668eff65fb7242f997d9a97:971912371&click_sum=159bf2c4&ref=shop_home_active_12
For the speaker SSR threshold level to be set to a lower value - will require some calculations. Let me ask Jhofland if he has suggested values. What would you like the threshold to be? 1.5v should not destroy a headphone. You might want to keep it to allow deep transient bass kick drums.
The threshold is controlled by an RC circuit R102 and C102. When DC charges this up there is a time constant and this powers an LED in an optoisolator. The output of the optoisolator feeds a comparator. R104 is a 200k resistor that sets the trip point of the comparator. One could make this value larger to force the reference voltage divider to a lower value. Something like 200k to 300k might make it trip at a lower voltage. Depends on where you want it. Changing R102 to a smaller value will let the RC charge up faster for a quicker response.
1.5V seems high to me for headphones, maybe its just me being overly cautious.
Randy
Think I will retract my question.
I just calculated that 1.5V into my 50 ohm cans will generate 45 milliwatts. Not enough to worry about.
And I'm pretty sure the DC offset will be very low, and go much higher than 1.5V if something fails, the entire point of this board.
Thanks
Randy
I just calculated that 1.5V into my 50 ohm cans will generate 45 milliwatts. Not enough to worry about.
And I'm pretty sure the DC offset will be very low, and go much higher than 1.5V if something fails, the entire point of this board.
Thanks
Randy
If you have a 4 channel amp then you need 4 SSRs. If the two channel run in bridged mode then one can be shared and assuming it is referenced to ground, the voltage is still fine. If you can get the I get al PSU rail voltages from the manufacturer (or measure it yourself) that would be the best way to know.
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