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Can the iConntectAudio4+ run off DC power directly? (By cutting off the power adaptor block...)

I’m trying to avoid spending the money to buy an inverter for my camper setup I’m living in now and so was wondering if I could cut the block off the ac-dc power adaptor for the iConnectAudio4+ and wire it directly into my 12 volt system...?

On the adaptor block
INPUT: 100-240V~50/60Hz 0.9A
OUTPUT: 12V 3000mA 36W

Comments

  • Yes, a car battery provides enough juice - the interface will only draw what it requires.

  • I'd recommend including a fuse, so a possible short won't trigger a meltdown of either your gear or the battery.

  • @Telefunky said:
    Yes, a car battery provides enough juice - the interface will only draw what it requires.

    It might work.

    But IMPO..... And out of caution... This is the type of experiment I'd put in the "if you have to ask... attempt at your own risk" category.

    The iConnectAudio4+ probably uses a switching power supply having a very clean and stable output voltage. Which is exactly what I would suggest powering it with.

    Automotive type systems "might" range in voltage from 10V to 15V depending on whether the vehicle is running (charging), or not running with the battery under load. It can also be a noisy voltage source. Which is why they sell car audio 12V noise suppression filters.

    A 3A inline fuse located at the + voltage tap, is a good idea to prevent fire.

    Personally I'd go with a properly installed power inverter. It would suck to blow a cap or in any other way fry the iConnect if it is not designed to tolerate over-voltage.

    (In experimental circuits I've had capacitors pop with as little as 1 volt over the spec rating. It's rare, I was stunned, but it taught me to build a margin of tolerance into the guitar amp circuit designs I used to build 30 years ago).

  • edited December 2020

    You might want to look at these. I’ve replaced a ton of bricks with them on various devices.

    https://myvolts.com/product/39020/Ripcord_12V_c+ve

    Edit: Yikes. Just saw 36w. Might as well stick with the brick.

  • DAC/ADC IC's are sensitive to noise. Even if the output from your battery subsystem is clean, other devices on the circuit can be injecting noise into the lines (LED's, lights, heaters, etc.) It might be a problem. I doubt if the CODEC's themselves are running at 12V, so they probably have voltage regulators that will clean up the supply to them somewhat. Those regulators might need pretty clean supply to them though.

    I'd be hesitant to do it directly off the 12V supply. I'd want some filters and chokes and caps in there to clean it up before I hit any of the audio devices.

  • edited December 2020

    The iCA4+ has full internal regulation (as you can tell by the heat it emits...)
    I’d clamp it directly to a 12V car battery without hesitation. The regulator parts are very robust items and will tolerate 25% overvoltage easily (at the expense of more heat).
    There‘s a lot of electronic gear supposed to be connected to 12V cigarette lighters.
    (wonder if they still build them)
    Switching PSU bricks are standard because they are cheap to build in the 1st place and not for their „clean“ output... plug one in beneath a guitar amp and you‘ll hear.
    Budget power inverters are equally infamous for their noise emission, btw ;)

    ps: this reminds me on people running tube gear from the US in Europe.
    Different voltage, different net frequency.
    They use a 60hz sine generator, amplify it to 110V with (for example) 200W power and feed that to power input of the device...

  • Thanks for the replies and suggestions!

    Maybe I should have clarified that I’m not looking to wire directly into the car’s system, but to an auxiliary deep cycle battery in my tow behind camper being charged by solar and occasionally shore power. Not sure if that’d make a difference though, but maybe less noisy, which I hadn’t even really thought about, but which now might be the main obstacle...

    @NeonSilicon What are these filters and chokes and caps that you speak of? Would what @horsetrainer suggested as 12v noise suppression filter do the job?

    But also I guess I would potentially run into an issue if the voltage drops below 12V when the battery is low so an inverter would I think help with that issue. But then again, noise issues from inverters as @Telefunky mentioned...

    Another option I was thinking about was getting a portable battery bank with an AC outlet which I could just charge with the solar and can also then be used for busking...just seemed kinda silly and inefficient to be converting DC power to AC then back to DC just because the cord is designed for an AC outlet...

  • edited December 2020

    Before making plans, I would first power the iCA4+ from an adjustable power supply and check how low the supply voltage can go without issues.
    A simple test is to record a low volume, low frequency sinewave and check the spectrum of the recorded file.
    That's good to know if you choose to power it from a separate battery pack.

    BTW, a simple but effective filter for the supply voltage can be as simple as this:

    Obviously you'd have to replace the BC with a power transistor, decrease R, increase C and make sure it's cooled down enough. In this config, there shouldn't be too much loss translating into heat though.

  • edited December 2020

    I own an iCA2+ and it can run USB powered. Don’t know if the iCA4+ can do the same. Anyway a great device, the virtual audio channels between two computers/iPads are pure gold.

    Update: I looked it up. Only the iCA2+ can be bus powered.

  • [...]

    @NeonSilicon What are these filters and chokes and caps that you speak of? Would what @horsetrainer suggested as 12v noise suppression filter do the job?

    But also I guess I would potentially run into an issue if the voltage drops below 12V when the battery is low so an inverter would I think help with that issue. But then again, noise issues from inverters as @Telefunky mentioned...

    Another option I was thinking about was getting a portable battery bank with an AC outlet which I could just charge with the solar and can also then be used for busking...just seemed kinda silly and inefficient to be converting DC power to AC then back to DC just because the cord is designed for an AC outlet...

    A simple Pi filter configuration would probably be enough. They are a capacitor-inductor(choke)-capacitor arranged in a π-like shape. You can most likely find a schematic for the job you are looking to do on-line. People have to have done this before.

    Using a rechargeable lithium battery pack for this wouldn't be a bad idea. RC car packs are available right in the 12V range. I bet that the RC vehicle folks have some efficient solutions for DC-DC charging of these packs. But, you'd really need to make sure that whatever you got could handle the current the iConnectAudio device needs.

    I'll give you a couple of examples of why I'd be a little concerned over the potential noise issues. A friend once sent me a recording he'd done of a Christmas time concert he had played at. There was a horrible hum over the entire recording. It turned out to be a 30Hz square wave over the entire recording that we had to notch out at every multiple of 30. He had the recorder (Zoom I think) plugged in to a power socket near a Christmas tree with LED lights on it. The square wave was from the tree lights injecting noise on to the power lines. The second example is from my house. The power inverters from my solar panels don't put out perfect sine wave power. So, sometimes, when they are running, I get some noise on some audio devices. My stereo system has no problem with it ever. It's well filtered. One of my tube guitar amps isn't so good with it. I've got tons of audio CODEC's for various projects and none of them ever has a problem with it. But, all of them will have layers of filtering between themselves and the wall socket.

  • Oh, I forgot to mention that the power regulators in the iConnectAudio device can probably handle some under voltage before they stop working. Doing as @rs2000 suggests would be a good test to see how much the sag before they stop working.

  • I stand corrected for the iCA’s heat emmission by regulators... :blush:
    There‘s an NCP3063 DC/DC converter inside. The driving peripheral semiconductors of this chip get fairly hot, but that‘s within specs.

  • @Telefunky said:
    I stand corrected for the iCA’s heat emmission by regulators... :blush:
    There‘s an NCP3063 DC/DC converter inside. The driving peripheral semiconductors of this chip get fairly hot, but that‘s within specs.

    Are they using that for the supply to the device or is it being used as a step-up to generate the +48V for phantom power?

  • edited December 2020

    Good point... the NCP is cheap enough for that single purpose, too.
    But I guess a full supply for the big inductors beneath it.
    Just touched them and there‘s more warmth than to expect from phantom power.
    ps for completeness:
    there‘s a 2nd DC/DC converter, TI 54521 (step down operation), probably for the processing unit(s) ARM Cortex 3 and 4 based.
    Overall design seems quite solid.
    Main conversion unit is an AKM4672 codec... surprise, surprise... 4 channels in, 6 channels out.
    Input channels are OPA1602 based (each backed by 2 pairs of transistors).
    Output channels with 4580 opamps.
    Thanks to the rear element of an old zoom lens (now serving as an excellent magnifier glas) I could decipher those incredibly tiny labels. o:)

  • @Telefunky said:
    Good point... the NCP is cheap enough for that single purpose, too.
    But I guess a full supply for the big inductors beneath it.

    Interesting. If they are using it for the regulation of the main supply, then there should be plenty of room for voltage sag and the post regulator filtering would have to be pretty good. Probably good enough to not worry too much about input line noise.

  • Well this quickly got above my head... 😆
    @NeonSilicon and @Telefunky have lost me for the most part but it seems the conclusion is that there’s not much to worry about with input line noise because of internal stuff I The ICA4+?

    @rs2000
    Before making plans, I would first power the iCA4+ from an adjustable power supply and check how low the supply voltage can go without issues.
    A simple test is to record a low volume, low frequency sinewave and check the spectrum of the recorded file.
    That's good to know if you choose to power it from a separate battery pack.

    What should one look for in the spectrum of the recorded file as you mentioned?

  • @ManWhoWouldBeStrings said:
    Well this quickly got above my head... 😆
    @NeonSilicon and @Telefunky have lost me for the most part but it seems the conclusion is that there’s not much to worry about with input line noise because of internal stuff I The ICA4+?

    @rs2000
    Before making plans, I would first power the iCA4+ from an adjustable power supply and check how low the supply voltage can go without issues.
    A simple test is to record a low volume, low frequency sinewave and check the spectrum of the recorded file.
    That's good to know if you choose to power it from a separate battery pack.

    What should one look for in the spectrum of the recorded file as you mentioned?

    It should be the same at different voltages. If it's a switchmode power supply, it can become noisy at the voltage limits and that will most likely show in your audio recordings.

  • @ManWhoWouldBeStrings said:
    Well this quickly got above my head... 😆
    @NeonSilicon and @Telefunky have lost me for the most part but it seems the conclusion is that there’s not much to worry about with input line noise because of internal stuff I The ICA4+?

    Sorry, most of the details are in fact not relevant to your question, but since the box was open anyway I thought I‘d share.
    As @rs2000 mentioned the design is fairly voltage tolerant, but without understanding the circuit fully one cannot tell to which degree exactly.
    The most important aspect is that the design is a good protection from flaws on the input voltage.

  • Cool. So then would the consensus in the end be that it is most likely ok to wire it into a 12 deep cycle battery system? Or even just use a car charger cord with a plug point size that fits correctly?

  • If the system is 12V lead acid battery based, I consider it safe.
    Dunno the details of modern Lithium Ion charging in solar supplies - in that case use a simple Multimeter to check voltage under charging conditions.

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