Audio Amplifier Accessories

[alkasar]

Originally Posted by firestorm

Hi Cristi,
is the speaker protection circuit for one channel or two ?
Thanks
fs

I have the module : it is stereo

[neilpaulx]

Hi Cristi,

I received the Soft Start module today and I'm impressed with the quality.

Just a question. I tried powering it up without a load and I noticed that without connecting pin 1 & 2 of J2 (ON/OFF switch), there is already 240V in pin 1 & 2 in J1 (LOAD connector). Is this normal?

Thanks,

[Cristi]

The voltage measured without any load is because of the small capacitor (100nF at 250V AC) connected across the relay. as soon as a load of at least few watts will be connected this voltage will drop to zero. the capacitor is used to eliminate click/pop noises when relays open or close.

[wagtail]

Hi Cristi,
I bought a SPC from you ages ago and have only now got round to using it .
I have a Helder Tripath TA2020 mk111 ( with a 14vdc PSU) I want to use it for.
Would a transformer with output of 11v 0.8amps be ok and how do I connect it
( just a beginner) AC1 and AC2 ? and what about GRD?
thanks
simon

[Cristi]

For a TA2020 based amplifier, must make a simple modification in order to use the speaker protection circuit. the TA2020 amplifiers have BTL output, so each output has about half the supply voltage at idle. the speaker protection circuit must be ground referenced to this half supply voltage instead GND. this can be done using a simple resistor divider, let's say 2 pcs 100R at 1W each connected in series from +12V supply to GND. then the GND reference of the speaker protection circuit must be connected to the middle point of the resistors. also, 2 pcs 100uF capacitors should be added in parallel with each resistors, and they will be in series from +12V to GND. one speaker protection module can be used to protect one amplifier channel, so for one amplifier should use 2 modules for complete protection. also, the supply voltage for the speaker protection module should be separate and referenced to the virtual GND, the 2 resistors middle point.

[wagtail]

"also, the supply voltage for the speaker protection module should be separate and referenced to the virtual GND, the 2 resistors middle point."
hi cristi,
would the 250Vac-11Vac, 0.08Amp transformer supply two SPC's?

[Cristi]

Yes, the 11V AC transformer is fine, after rectification and filtering you will get about 14V DC with no load, and will drop to 12-13V when the relay is closed. the current draw is below 40mA, so is fine for both modules.
Make sure you understand what i mean with the virtual GND, otherwise will not work.

[NissanSR20Man]

Crisit, can the Power Supply and Protection Circuit [PSPC] be modified by you to allow for +/-70V rail operation? I would need 4 PSPC boards modified in total.

This is to be used on IRS2092 L25 design, operating at +/-70V.

[Cristi]

The only components which have to be changed to allow higher voltage to be used are the electrolytic capacitors, from the current value, 4700uF at 70V to something similar, rated for 80V or 100V. with the actual capacitors the maximum voltage should not be over +-68V. higher voltage rating capacitors have lower capacitance for the same can size. for example at 80V can be 3300uF and at 100V, 2200uF or 2700uF. If you need them, contact me and i will search them and use for the boards which you want to order.

Also, the PSPC has a lot of features, described in manual which can be used for any class D amplifier, not only for L25. it has power soft-start, speaker protection circuit and peaking detection circuit. please read the manual for more details. http://www.connexelectronic.com/documents/PSPC.pdf

[NissanSR20Man]

Originally Posted by Cristi

Also, the PSPC has a lot of features, described in manual which can be used for any class D amplifier, not only for L25. it has power soft-start, speaker protection circuit and peaking detection circuit. please read the manual for more details.

I know, the PSPC is like seperate modules as mentioned above, but you get a peaking circuit for free. I will keep the cap voltage issue in mind.