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Alternative to Faceplate/Preamp unit for Table Radios...

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  • tomzarbo
    replied
    So I messed with this a little bit more today. I took a video of it on my phone. It can do more that what I showed, but at least you can get a feel for how it operates.

    Link: https://www.youtube.com/watch?v=W5hF...ature=youtu.be

    One thing I forgot to do is to press the volume knob, that gives you up/down for bass, treble, balance, fader, brightness, contrast, saturation, hue, beep on/off, and maybe a few other things.

    I don't mess with phone dialing features on phones, so I'm not sure what any of that stuff does -- make/receive calls through it? -- but it looks to work like a phone once connected through Bluetooth. It can obviously play Bluetooth through the phone as well as good old music.

    The FM radio pulls stations in just fine. It's not amazing I guess, but it works. Once a station was dialed in, it seemed stable with no static. I noticed also that rather than just 98.1 it can do 98.15... not sure if it's really dialing in the station with more accuracy or it's just a gimmick.

    The units built-in amp will power a set of speakers (at least one pair of 4 ohm Neo Nano's) to fairly loud levels without sounding bad. I even hooked one side to an 8" subwoofer that is my footrest and it had no issues with that. I only had it hooked directly to the speakers for 8-9 minutes, but it didn't get hot on the back, mid 90 degree F but I wasn't cranking it super loud either. I suspect with low to medium volumes with two speakers connected, it would be okay. Sound quality seemed fine.

    There was a slight on/off click when powered with the built-in amp. The click is louder when connected to an amp through the RCA jacks. I think the quality is better with RCA outputs, though.

    The antenna power line is active as soon as the radio is turned on, no matter what mode it's in; so using it to power a relay or delay turn-on for an amp should be okay I would think depending on how much amperage it can deliver.

    The included instruction booklet is nearly useless except for the wiring diagram, which is also on the back of the unit. The instructions are for a different unit... actually several different units, but not this one exactly. Doesn't matter, it's self-explanatory pretty much.

    I'm not really super-adept at fiddling with this stuff, but I just wanted to give a basic idea of how the screen works and what a few of the features were. I probably should have gone over it several times, then made the video, but...

    Bottom line is, it works fairly well, not as clunky in operation as I thought it would be. The video screen is attractive, the graphics are not blocky or jaggey, it looks like it belongs in a modern car actually.

    It will make a real nice table radio or boombox head unit. With one of the adjustable on/off relays that Mike was referring to connected to the power antenna lead, it could potentially be amp-quiet when turned on/off as well if using with an external amp.

    I'm leaving some stuff out I'm sure, if you have a question about something I didn't get to, let me know.

    TomZ





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  • Dukk
    replied
    I have yet to ever buy from Ali as I find it frustrating to navigate and when I do find something I need a minimum order of eleven million of them

    Some units have display settings that can turn it off when powered down.

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  • tomzarbo
    replied
    I kind of thought that 280 milliamps was sort of a lot for it being on 'standby' mode, but since it's a car radio and they're not at all trying to save every milliamp of draw, 280 milliamps isn't all that much I guess. Still, I was expecting less than that. It does have the screen on all the time when off to display the time/clock.

    Mike, thanks for the link for the convertor. Pretty cheap, and I don't mind waiting a few weeks for this stuff.
    I'm not clear on what it would be used for in this case though?

    Dukk, I didn't think of the antenna lead switching off when changing sources other than the FM radio. I'll test that out to see.

    It does have settings that need to be remembered such as all the FM presets, the color of the LED glow on the face, and other stuff I guess.

    I'll try to run through every option when I get a few good hours this week or weekend.

    It's funny, I search for something at Aliexpress and it seems unless I get the wording just right, I can't find what I'm looking for. Other things... there are so many hits that come in... they have dozens and dozens of car stereos in the double DIN size, some of them look similar, maybe just different faces to basically the same guts. But you're right, not many of the smaller ones, fewer with touch screens.

    TomZ
    Last edited by tomzarbo; 02-26-2020, 05:42 PM.

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  • Dukk
    replied
    Very nice. I was cruising Ali a couple weeks back for something just like this. I found a few but single DIN touch screen headunits are harder to find.

    RE: Antenna turn on. This *might* only activate when Radio is selected. Traditionally, car radios that have both an amplifier turn on lead (on continuously when head unit is on) and an antenna lead will turn the antenna lead off when listening to alternate sources to put the power antenna (remember those?) away.

    The built in amplifier section shouldn't have any parasitic draw, but who knows. The draw when off is to support the clock and most likely radio presets and any DSP settings as they are usually volatile memory.

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  • Millstonemike
    replied
    Tom,

    Here's a 5V isolated DC-DC converter rated up to 200 ma. ~$2 from Ali-Express.

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  • tomzarbo
    replied
    I can say a couple of things now...

    * It's almost weightless, very light.

    * It doesn't look like the 'Wattage' speaker output circuit can be removed from the equation; or I should say it's not on it's own 'Amp-Only' board... The board in the back looks to have more than just 'output generating doo-dads' on it, but I'm not 100% sure about that.

    * I'm not sure how much amperage would be saved by removing the output stage from the equation. The amp chip is screwed to the back aluminum 'heat sink'... could the leads to that chip just be clipped, saving those milliamps? After about 20 minutes of messing with it, it didn't get even warm, so leaving it as-is wouldn't be a problem I'd think.

    * The remote control has the worst plastic smell I've ever inhaled. But, it does have buttons that go 'click,' it uses two AAA batteries, and it feels rather good in the hand, I like it a lot.

    * The screen resolution is very good, and the touch screen is adequately responsive to button presses... and most of my devices don't seem to think that I'm a living creature as they often don't register my finger touches as 'presses.'

    I'll take a short video of how several of the functions operate if I can to show how it functions.

    Click image for larger version

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    TomZ

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  • Blenton
    replied
    Oohhh, jazzy!

    I picked up a couple Blaupunkt Toronto media receiver a little while back that have a similar feature set to the less expensive model. BigDWiz of YouTube famedom tested the unit and made them well known. At the time, they were $12. $12!! And they used to be $10!!!! Now they r a whopping $19. But I used one with a meanwell power adapter and and old 2 channel Fosgate amp to power four 6.5” car speakers. For $12 I was blown away!

    Interested to to see what u have to say about this one.

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  • tomzarbo
    replied
    I got this thing tonight and messed with it just a bit.
    I didn't hook up to the speaker outputs yet, just the RCA outputs. No buzz or noise hooked up to a lepai 2020 amp. Looks to draw about .28 amps with the unit "off" with the time displayed on the screen, and about half an amp with the unit on.

    I won't say too much until I get to spend a little time putting it through it's paces, but so far, so good; The interface is actually intuitive for one thing.

    Click image for larger version

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    More in a few days...
    TomZ

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  • Millstonemike
    replied
    Originally posted by tomzarbo View Post
    I thought that the antenna output voltage stayed 'on' as long as the radio was on though. So it's a temporary voltage for a few seconds? Well, looks like I have a few more things to learn!
    TomZ
    Not sure about the antenna voltage timing. I'd bet it's on as long as the unit is on powered - like a turn-on output for a remote amp. What I meant was the delayed relay can buy you extra time for the head unit to settle down before powering the amp. If that's needed.

    I'd love to get one of these to tear down - perhaps amputate the power section. Alas, I have a major project going on in my other hobby ....

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  • tomzarbo
    replied
    Originally posted by Millstonemike View Post

    At 12 V, power out into 4 ohm drivers is about 15 W rms (1/4 of your TPA9274 amps at 24 V). The standard 52 rms for a 4 channel head unit is 13 W rms per channel according to CE measurement defintions. Plan on adding an external amp ... and dealing with ground loop. Unfortunately, the couple hundred ma capacity of the isolated DC-DC converters is likely not enough to power it, even used only as a head unit (but you can measure that). A non-isolated regulator (linear or buck) should handle it no problem. If ground loop is a problem, you could try decoupling caps on both the positive and negative signal sides between the line outs and the external amp.

    And don't forget that 12 V delayed relay module if the antenna output is too quick for a simple relay. And add 70 ma or so the the 12 V power source load to keep the relay closed.

    I'd be interested in the measured power draw when get it.
    Mike,
    thanks for reaffirming my suspicions on the projected wattage output of the unit. I didn't expect much out of it anyway. And truthfully, anything I build with a head unit this big in it will have drivers that will need more than 12 or 15 watts to make it sing.

    I was thinking the same thing with using a buck converter to reduce the incoming voltage to 12V as opposed to the isolated converters I've been implementing. I also have a few isolated line out thingy's from the Toni Table Radio build which I didn't end up using if needed.

    Regarding the antenna voltage lead... I thought that the antenna output voltage stayed 'on' as long as the radio was on though. So it's a temporary voltage for a few seconds? Well, looks like I have a few more things to learn!

    Don, I do seem to be on a never-ending quest to find a diamond-in-the-rough with these preamps. Hopefully this is a decent unit, we'll see when I get it.

    I was going to quote your post, but I don't seem to be able to multi-quote anymore? Not sure what I'm doing wrong there.

    TomZ

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  • donradick
    replied
    Nice find, Tom - and your usual thoroughness in exploring capabilities and possibilities.
    Looking forward to assessments of the SQ. The $20 piece would be perfect for boombox for my shop.

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  • Millstonemike
    replied
    Originally posted by tomzarbo View Post
    ... and line-outputs for L and R and even a sub. There isn't much listed as far as it's output capabilities, but even if it's lousy, it can be bypassed. There are options to change the color of the buttons and knob to match the rest of the radio's theme, or it's surroundings I guess. It also has a power antenna turn-on lead which might be able to be connected to a relay that will turn on a seperate amp, that's kind of nice!

    TomZ
    At 12 V, power out into 4 ohm drivers is about 15 W rms (1/4 of your TPA9274 amps at 24 V). The standard 52 rms for a 4 channel head unit is 13 W rms per channel according to CE measurement defintions. Plan on adding an external amp ... and dealing with ground loop. Unfortunately, the couple hundred ma capacity of the isolated DC-DC converters is likely not enough to power it, even used only as a head unit (but you can measure that). A non-isolated regulator (linear or buck) should handle it no problem. If ground loop is a problem, you could try decoupling caps on both the positive and negative signal sides between the line outs and the external amp.

    And don't forget that 12 V delayed relay module if the antenna output is too quick for a simple relay. And add 70 ma or so the the 12 V power source load to keep the relay closed.

    I'd be interested in the measured power draw when get it.

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  • tomzarbo
    replied
    Originally posted by jhollander View Post
    Tom, looking forward to your review, what's the expected delivery?
    Should be here in less than a month if there are no Coronavirus restrictions.

    Just thinking, it may make a decent little mid-fi faceplate/preamp for a larger-amp'd home stereo unit, assuming it's not garbage.

    TomZ

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  • jhollander
    replied
    Tom, looking forward to your review, what's the expected delivery?

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  • tomzarbo
    replied
    DJG... you know my wife mentioned that. I wondered if I should spray every incoming pkg with Lysol or a flame thrower or something.

    Kevin... I know, I don't know how a profit can be made -- or much of one anyway -- from stuff like this at that price including shipping. I'm thinking that quality control on many of these cheaply made electronics items from China is non-existent or shoddy at best. I've had so-so luck with stuff from Aliexpress in the past, but at least I'm usually only out a few bucks when I get it and discover it's junk.

    There have been a few jewels in the muck and mire that keeps me hopeful!

    Happy Presidents Day everyone!

    TomZ

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