Ready-to-Run (RTR) SSR DC Speaker Protection and Delay GB

[mbrennwa]

Audio inputs are XLR. PSU DC input and speaker out are all bananas. I am using two older MeanWell SP-240-24 SMPS supplies, and they don't complain about the capacitance. The only issue is their fan noise, so I am looking at the MeanWell LRS types without fan.

 

[mbrennwa]

Are there any updates regarding the new batch of the DC protection boards?

 

[myl]

after modifying, can it be used in balanced output amplifier ?

 

[xrk971]

Due to Lunar New Year celebrations in China, all PCB production has halted for past week or so. So no new updates until folks get back to work from their celebrations.

 

[gary s]

Also the current outbreak of the Corona Virus in China may also slow things down as the authorities there lock down more cities, it is not getting any better either according to the TV reports here.

 

[xrk971]

after modifying, can it be used in balanced output amplifier ?

If you only run one wire from BTL amp through the SSR (+ve amp in and speaker out) and connect the -ve of the amp directly to the speaker without going through the SSR -ve pin (as it is tied to GND and would short our a BTL amp). Then connect the +/- of the SSR power supply to the + PSU and amp GND, it should work. If DC is detected, it will break the connection between the two amp outputs.

 

[xrk971]

Sorry, I am incorrect in saying that the above - the BTL output has DC in one leg and that will cause the SSR to shut off.

So, no this SSR cannot be used with balanced output or bridge tied load amps.

 

[xrk971]

Hi Folks,
Just wanted to let you know that things are a bit quiet (no activity from the factory) due to Lunar New Year in China. Now with the Corona virus epidemic and various lock-downs going on, I am not sure how this may affect business where this factory is set up. Will keep you posted though.
Cheers,
X

 

[schlomoff]

Hi Folks,
Just wanted to let you know that things are a bit quiet (no activity from the factory) due to Lunar New Year in China. Now with the Corona virus epidemic and various lock-downs going on, I am not sure how this may affect business where this factory is set up. Will keep you posted though.
Cheers,
X

quiet

 

[mbrennwa]

Is it possible to reduce the DC threshold to switch off? I am considering to use the SSR in a headphone amp, where the 1 VDC threshold is a bit too much for my tastes.

If it is possible: how do I modify the boards? I guess it's a matter of changing some resistors...

 

[xrk971]

Is it possible to reduce the DC threshold to switch off? I am considering to use the SSR in a headphone amp, where the 1 VDC threshold is a bit too much for my tastes.

If it is possible: how do I modify the boards? I guess it's a matter of changing some resistors...

We have a HP amp DC offset protection system designed just for headphones that I tested. Works very well. Similar in operation but with smaller components due to lower current requirements and threshold is lower. Threshold is +/-500mV DC. Still low RDSon MOSFET so that sound quality is not affected.

Cheap as Chips OPA1688 Low-THD Muscle Amp

 

[xrk971]

If there is more interest in this headphone SSR DC protection circuit I can form a new GB for it.

 

[jhofland]

To answer your question mbrennwa, the thresholds on the RTR speaker protection circuit are established by the IR LED internal to the sensing opto and are not adjustable.

 

[xrk971]

Thanks for clarifying that, Jhofland. For the HPA DC protect circuit above, it is controlled by resistor setitngs (R5/6/7/8 and R9/10/11/12) as a comparator is used rather than the LED of an opto-isolator to detect the DC offset.

 

[mbrennwa]

If there is more interest in this headphone SSR DC protection circuit I can form a new GB for it.

Yes! Interested!

 

[xrk971]

Ok, I will post a GB interest thread and see how many people would consider this as a RTR unit or as a DIY (self assembled SMT project). These are not hard to solder as there are no hidden solder pads.

 

[xrk971]

New GB thread for the Headphone RTR SSR DC Protection board here:

https://www.diyaudio.com/forums/gro...ier-dc-protection-modules-gb.html#post6075411

 

[rebone]

Hi X
I have pre-ordered 2 units from Etsy

GB update

tcpip 6 units USA
mbrennwa 6 units Switzerland *Pre-order Placed*
Andyr 4 units AUS *Pre-order Placed*
Schlomoff 4 units FR *Pre-order Placed*
jwjarch 4 units USA *Pre-order Placed*
Meanie 2 units Singapore *Pre-order placed*
rebone 2 units Spain *Pre-order placed*

all the best

 

[xrk971]

Thanks, Rebone! Still waiting for fabrication house to finish up. The whole corona virus issue has slowed things no doubt.

 

[Vunce]

I finally installed the DC speaker protection boards in my PeeCeeBee V4H. I used the +24/GND Aux output from the Cresnet SMPS to power the protection boards.
Works as advertised!