The TDA7396 amplifier IC produces 40W of audio plus about 33W of heat for a total of 73W when driving a 2 ohm speaker and is powered with 16V. The step-up converter must produce 73W/16V= 4.6A for one amplifier or 9.2A for stereo.

What is the step-down converter for?

 

What is the step-down converter for?

Pin #4 needs 5V to take it out of standby mode. Or this was my understanding of it.

 

Pin #4 needs 5V to take it out of standby mode. Or this was my understanding of it.

Pin 4 is a diagnostics output that shows a 10k resistor to Vref to maybe make the amplifier work when diagnostics does not detect an error.
The text says that the 10k resistor can be connected between +5V and the supply voltage so +5V is not needed.
The datasheet does not say the amplifier works when the 10k resistor to a positive voltage is missing.
The datasheet does not say the maximum allowed current from pin 4 so it cannot light an LED bright enough that is in series with a 10k resistor.

Figure 3 in the datasheet shows the Standby pin 8 connected to a uC or to VS which is the supply voltage. Figure 14 in the datasheet shows pin 8 switched between 0V (amplifier is turned off) and VS which is the supply voltage (amplifier is turned on). 5V is not needed, the amplifier turns on when pin 8 is 3.5V or more up to the supply voltage.

 

So it's pin #8 that's the (off/on) and not pin #4. It showed a 5V and Vs on pin #4, and only Vs and an arrow pointing out on pin #8. So the remote wire coming from a radio will work? or place a micro switch on the PCB and a toggle switch under the dash... …. The arrows pointing out from the IC were confusing me.

 

Yes, the remote wire from a car radio will turn this amplifier on and off.
Pin 4 is a diagnostics output that can be powered by a 10k resistor from 5V to VS. The block diagram has LTS DISABLE connected to it so it might need the 10k resistor even if you do not use diagnostics.

 

Yes, the remote wire from a car radio will turn this amplifier on and off.
Pin 4 is a diagnostics output that can be powered by a 10k resistor from 5V to VS. The block diagram has LTS DISABLE connected to it so it might need the 10k resistor even if you do not use diagnostics.

Boy did I get that one wrong! Thanks AG for not letting me mess up.
I'm looking at purchasing a new converter and I've showed this one before:
http://www.icstation.com/adjustable...regulator-with-voltmeter-display-p-10525.html
It has 7 amps in and 6 amps out. Still looking for a little better one. Their so tee-ninie. It's only like 2.625 long. $5.54 each

Another dumb question. Will it allow the normal sound to come through when the amp is not powered or will it just shut down.

 

The voltage stepup converter can be programmed to produce no noise interference. But its 75W of maximum allowed power is very close to the about 73W maximum input power to one amp. I don't know if the converter melts or if it smartly shuts down when it is overloaded.
Don't you want twice the converter output power for stereo?

When the amp is in Standby or if it is not powered then there will be no sounds from the speaker.

 

Don't you want twice the converter output power for stereo?

I'm looking around now AG. And they will be mono meaning, one amp will play left side and the other right. One amp per speaker just like the original. bolted on the bottom of the speaker itself.

When the amp is in Standby or if it is not powered then there will be no sounds from the speaker.

Then I will need to add that relay in my PCB to switch from one to the other. when no power is supplied to the amp it bypasses the amp and goes to the speakers.
The 2 ohm speakers should arrive tomorrow.
Just for you AG the new Mindblower symbol.

Still working on color

 

Then I will need to add that relay in my PCB to switch from one to the other. when no power is supplied to the amp it bypasses the amp and goes to the speakers.
The 2 ohm speakers should arrive tomorrow.
Just for you AG the new Mindblower symbol.

Still working on color

If a relay switches the speakers to the output of a car radio then the amplifiers in the car radio will try to produce 33W each and melt or blow up. A car radio blower.

 

Toggle switch under dash, No power to amp, double relay is in bypass mode goes straight to speaker. Click toggle switch power to relay switches to second input and turns on amp. No feed back through the other way.
something like this:
https://www.digikey.com/product-detail/en/kemet/EE2-12NUH-L/399-10996-2-ND/4291062
datasheet:
https://content.kemet.com/datasheets/KEM_R7002_EC2_EE2.pdf
Still looking for one that can handle a few more amps.

 

A ordinary car radio has built-in amplifiers designed to drive 4 ohm speakers. A 2 ohm speaker is like a shorted speaker which draws double he current to melt, smoke or blow up the amplifier. The radio's fuse will also blow up.

Why turn off and bypass your amplifier?

 

Why turn off and bypass your amplifier?

sometimes you don't want loud music (?) and this will make it where the amp isn't on 100% of the time. Most amplifiers have an off/on switch. The original mindblower when the "boost switch" was off you could still hear music at normal level of your radio. That's why I asked the question about could you still hear music with no power to it.

A ordinary car radio has built-in amplifiers designed to drive 4 ohm speakers. A 2 ohm speaker is like a shorted speaker which draws double he current to melt, smoke or blow up the amplifier. The radio's fuse will also blow up.

It's rated for a 2 Ohm speaker you made the suggestion of going to one to make it louder. I have thought about fuses and protection of all types.
Remember I said I was crazy but, I'm not stupid. The Mindblower had an inline fuse to stop anything from melting. But often people replace the one that blew with a bigger one thinking that solved the problem and only creates a bigger one.
I looked around for a while yesterday for a better converter. I looked at Drok, ICstation, Amazon, Ebay and a lot of others. The one I posted was about the best you can find in that voltage range. found another with 80W but only 5 amps output compared to 6 amp output. The only way to get a better one than off the shelf is to design it.

 

The amplifiers in the TDA7396 draw only a small current more than just the car radio at low volume so switching off the new amplifier does not make much difference. Some car radios will be destroyed when overloaded with 2 ohm speakers anyway.
The 40W into 2 ohms from one TDA7396 with a 16V boosted supply will be only a little louder than the 15W into 4 ohms from one ordinary car radio speaker and will actually sound slightly less since an ordinary car radio has 4 channels (60W). If you compare your amplified speakers in stereo (2 channels totalling 80W) with an ordinary car radio (4 channels totalling 60W) then you will barely hear the slight increase in loudness.

The patent on the MindBlower speaker did not show and did not say anything g about a "boost" switch. A search on Google shows a question about it and an answer that said the "boost" switch simply disconnected the speaker's tweeter to make the sound more bassy.

Of course each of your amplified speakers must be powered from a fuse to prevent a fire in a crash or from a circuit failure.

 

The patent on the MindBlower speaker did not show and did not say anything g about a "boost" switch. A search on Google shows a question about it and an answer that said the "boost" switch simply disconnected the speaker's tweeter to make the sound more bassy. It also had a retifier

Then that would not explain the first models that did not have a tweeter or a woofer and still had the "Boost" switch. It also had a rectifier to turn the bass up and down and a toggle switch to turn the amp off. Or as far as my ears could tell.
And there you go again you help me and tell me to do it this way? When I agree and do it that way all of a sudden it won't work. Now it's going to blow up?

 

The first model had a cheap "whizzer cone" instead of a real tweeter. If it had a "boost" switch then maybe it added a capacitor (not a rectifier) to muffle the high frequencies. If it had a bass control then maybe it simply made low frequencies more sensitive without increasing the maximum output power. It had an on-off switch because its simple amplifier did not have a standby function, or maybe because old car radios did not have a remote on-off output. How will anybody know if their car radio has a remote on-off output? Then your amplified speakers will need a manual standby switch.

Your amplified speaker will not blow up because the TDA7396 IC is able to drive 2 ohm speaker.
But the car radio will blow up if you switch 2 ohm speakers to it because it is designed for 4 ohm speakers and your 2 ohm speakers will overload it and cause the car radio to blow up.

 

Now from my understanding of how a radio and amplifier work is the amp is not drawing power from the radio. The radio is only putting into the amp. The amp will produce the power, wattage or amps the speaker will need. You make it sound like the radio can't handle a 2 ohm speaker. How do you know what radio a person has in their car? Looked on the radio box I bought and nowhere does it say only for 4 ohm speakers.

Then your amplified speakers will need a manual standby switch.

Now your getting the picture.

 

A normal car radio has four amplifiers in it that each produces 15W into 4 ohms. They are not designed for 2 ohm speakers.
Crutchfield US sells two hundred and thirty two car radios. Most owners manuals say the speakers should be 4 ohms.

A car radio designed for 2 ohm speakers will use up to double the current and produce up to double the power of a radio designed for 4 ohm speakers. Its heating will also be doubled. Therefore it will cost much more. 15W x 4 in a car is more than enough.

Crutchfield US sells eighty-six 6" x 9" car speakers. Only two of them are 2 ohms and sixty-six are 4 ohms.
Then only 2.9% of the 6" x 9" speakers they sell are 2 ohms.

 

I'm going to build about 4 of these AG. If they don't or won't take a 2 ohm speaker, I'll just buy another $17.00 radio, get some 4 ohm speakers and build that one and see what happens. Remember Sonoran said there is a reason there's a "re" in research and development.

 

Speakers came in. Got a whopping 300 Watts Max on front.

 

300 Whats (with horrible distortion) is about 40 or 50 Watts (at low distortion just before clipping).