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question: car amplifier at home (diy)

Discussion in 'Audio' started by evolandlupiz`, Apr 14, 2019.

  1. evolandlupiz`

    evolandlupiz`

    7
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    Apr 14, 2019
    i've got a small project going on at home for hooking up my car amplifier and subwoofers in my room. i'd like to ask for a bit of help in making sure my circuit will be okay and a bit of help in making sure i get the right power to the system. what power source in my at home area would you recommend, and can you check to see i've got the correct equipment?

    for the power source i was thinking of an `adc convert 3000 watts`, thoughts?

    this is what i'm using:

    (1) x2 subwoofers xfire xfr 12" (*specs below)

    (2) x1 amplifier 2400 watts memphis srx 1200d.1

    (3) x1 ren20kit 4 guage

    (4) x1 bass knob

    (5) x1 remote switch to turn on amp



    * * * SUBWOOFER SPECIFICATIONS * * *

    XFR12.44 12” dual 4Ω Subwoofer

    GENERAL

    SIZE 12" SUBWOOFER

    Voice Coil DUAL

    DC Resistance (Ω) Dual 4 ohm (Ω)

    Peak Power (Watts) 2250W

    Continuous Power (RMS) 750W

    Sensitivity 90dB

    Effective Frequency Range 26Hz - 150Hz

    Cone Material Kevlar Woven Reinforced

    Surround Material Precision Linear Drive dual stitched resin fiber

    X-MAX 33MM 1 Way



    link: link to xfire item on ebay



    * * * AMPLIFIER SPECIFICATIONS * * *

    Mono subwoofer amplifierPeak Power 1,200 watts RMS x 1 at 1 ohm750 watts RMS x 1 at 2 ohms400 watts RMS x 1 at 4 ohmsClass D amplifier technologyVariable low-pass filter (30-250 Hz, 12 dB/octave)Selectable bass boost (0, 6, 12 dB at 45 Hz)Variable subsonic filter (15-50 Hz, 12 dB/octave)RCA and speaker-level inputsWired remote level control includedFuse rating: 40A x 34-gauge power and ground leads recommended —

    wiring and hardware not included with amplifier12-9/16"W x 2"H x 8-1/8"D



    link: link to memphis item on ebay



    * * * AMPLIFIER KIT SPECIFICATIONS * * *

    1 x 20 Apx 4ga Power Wire (red) with Flexible Strands, 5 m

    1 x 20 Apx Ground Wire (grey) with Flexible Strands, 0.8 m

    1 x RCA Stereo Audio Cable (blue), double shielded, 5 m

    1 x 0.5mm^2 remote wire, 5m

    1 x AFS fuseholder with 60A fuse



    link: link to renegade item on amazon



    * * * BASS KNOB SPECIFICATIONS * * *

    link: bass knob on amazon

    * * * REMOTE SWITCH SPECIFICATIONS * * *

    link: switch on amazon
     

    Attached Files:

  2. Bluejets

    Bluejets

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    678
    Oct 5, 2014
    Normally high power output systems run at a much higher voltage than a 12v supply, current requirements being the killer.

    Even most car amplifiers are designed for around 16v which they never get.

    What sort of current requirements in your system, no one here knows.
    Perhaps it might be calculated out but does it allow for when the sub-woofer requires some punch and deprives the rest of the system resulting in clipping and distortion.
     
  3. evolandlupiz`

    evolandlupiz`

    7
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    Apr 14, 2019
    i was running this specific setup in my 08 bmw with a ~165A alternator and a 12.5V/1000W battery and it worked fine, so I was thinking for the power supply unit getting an ADC converter since it will be in my room. i know i could go get a 12.5V battery supply and a battery charger but i am a bit nervous about hazards associated with this setup, that's the motivation for the ADC. with this being said, apologies since i don't consider myself an expert, but i would like to get it right. if i go the route of a convert or a battery charger such as, 12V battery * 200A current = 2400W amplifier, am i right? thank you.
     
  4. BobK

    BobK

    7,575
    1,633
    Jan 5, 2010
    I just built a new pair of speakers. They are powered by a 16V AC adapter and a 16 Watt amplifier. They can produce sound way louder than I would ever want to listen to. Really, painful level of sound from 16 Watts. And you need 3000?

    Bob
     
    hevans1944, davenn and duke37 like this.
  5. evolandlupiz`

    evolandlupiz`

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    Apr 14, 2019
    Hello Bob, Thank you for your reply.
    I'm not sure if you peeked at the amplifier, but
    this systems amplifier has the following characteristics:
    Peak Power 1,200 watts RMS x 1 at 1 ohm
    750 watts RMS x 1 at 2 ohms
    400 watts RMS x 1 at 4 ohms,

    I'm trying to figure out what my source should be, either an AC to DC converter so it's powered from the wall outlet to through the converter, an independent PSU like those used for digital computers, or something like a regulated power supply, i don't know which one to chose from.
     
  6. dave9

    dave9

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    153
    Mar 5, 2017
    Sure but consider that he has used these in a vehicle so probably already has severe hearing loss and needs the volume. ;)

    Personally, I too, think shooting for lower wattage would be reasonable. I'd hook it up to an ATX12V computer PSU since I have some lying around. I also have old motherboards, video cards, etc that I could harvest mating connectors off of, though there are also some fairly inexpensive ~$30 40A/12V switchers on ebay sold for LED lighting.

    What is being called an "AC to DC converter" is probably similar enough to a "independent PSU like those used for digital computer" except those have multiple power rails. Depending on the protection circuit in the computer PSU you might have to put a dummy load on the 5V rail, maybe other rails too on better PSU, so the overvoltage protection doesn't kick in and shut it off. That is if it has group regulation, if independent it may not need this, yet will typically cost more.

    Either those are a "regulated power supply". If you mean a linear supply rather than a switcher, it's going to be very expensive to get a large transformer, and the capacitors won't be cheap either. It is what some audio purists would do but then those types of people probably wouldn't use a car audio system in their home, would want at least a class A/B if not class A, instead of a car amp that is probably class D.

    I definitely would not use a battery. You'd end up spending as much on the charger for it as a dedicated PSU would cost, and would have to leave that running all the time unless you spend hundreds of dollars on a large enough battery array to continuously power it.

    The most practical thing to do would be accept much much lower output power or just sell all the bits and buy a home stereo.
     
    duke37 likes this.
  7. Ylli

    Ylli

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    Jun 19, 2018
    Don't know what an "ADC" is, but for a power supply you will need nominally 14 volts at 50 - 60 amps.
     
  8. evolandlupiz`

    evolandlupiz`

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    0
    Apr 14, 2019
    so what you're suggesting is even though the amp can run up to 2400w it's not necessary to run it that high, simply get a PSU for around ~$30 (40A/12V) and don't crank it all the way up? essentially what i'm trying to get done is something similar to the youtube video `How To Wire Car Audio Amplifier (In Home) NVX JAD1200.1 Bass Amp & Crescendo LOGIC 12V AGM Battery`.

    or

    sell the pieces!!! i don't know why i didn't think of this.
     
  9. evolandlupiz`

    evolandlupiz`

    7
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    Apr 14, 2019
    Thank you for taking some time to write out a response, what I meant is AC to DC converter, it's a module that takes AC input (from the wall socket) and outputs DC.

    for the record, thank you everyone for sharing your thoughts, i initially took this sound system out of my car since my living area has recently experienced car break ins and all that good stuff, so i thought it be better to put this system in my room.
     
  10. dave9

    dave9

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    Mar 5, 2017
    Yes, it is not necessary to crank it all the way up. If you are able you might also reverse engineer the amp and change the gain on it. Ideally a full turn of the volume knob will be a full range of available output power. Granted you can artificially get that with a different resistor value pot as the volume control, but with less gain you increase the sound quality all else being equal.

    I suppose I'm saying that if you are starting out with a car audio system, there is no way to make that "great" based on just picking one PSU over another unless you hack the heck out of it to the point where it didn't make sense to use a car audio system.

    I would just get the cheapest amps you can, hunting for a PSU to power this, pick a budget and see what that will get you. I would not spend more on a PSU than a home stereo would cost. Granted, a certain % of the cost of a home stereo IS the PSU in it, but talking high end, a torroidal transformer and regulation, is way too expensive for the result for a 12V based system.

    Have you considered your home wiring yet? Suppose 110V at 15A (typical), that's only 1650W if the amp were 100% efficient which it definitely isn't. You would need a 220VAC circuit to do this at all with typical 15A/20A household wiring.

    Again I would go for a computer ATX12V PSU, all of them are designed in NA for operation within that 15A limit. You may find something cheaper from China as a 12V-only PSU, but high power inexpensive Chinese PSU... plugged into a wall... makes me nervous.
     
    Last edited: Apr 15, 2019
  11. evolandlupiz`

    evolandlupiz`

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    Apr 14, 2019
    after doing some math and some thinking on how far i want this to go, my budget, i could spend around $150 for a PSU for the current amp that i have. i did consider a transformer but yes you're right that would get very pricey very fast, and something about a transformer sitting next to me in my room, i don't know, it doesn't feel okay.

    i do agree with you the idea of using the ATX12V PSU is the best solution, the issue now will be which one...
    my amp has a power handling rating of 400w rms at 1 ohms (750w rms at 2 ohms), i have two subs 750w rms at 4 ohms,
    so after a peek through best buy, `CORSAIR - CX Series Modular CX750M 750W 80 Plus Bronze ATX Power Supply - Black`, single 12.5v rail...any thoughts? or is it too fancy? Thank you.
     
  12. Bluejets

    Bluejets

    3,375
    678
    Oct 5, 2014
    Why..?? They've been around doing their job quite well for the last 100 years or so.


    Pretty sure Dave9 was referring to the cost perspective, not necessarily the "best" as you quoted.

    Batteries are not referred to as Watts.....capacity is Amp hour. Motor vehicle batteries also are rated as their CCA ability (cold cranking amps)
    The latter important in this instance.

    You might find getting more than 11.7V out of an ATX supply a bit hard to come by which will only lead you to other problems as mentioned previously.

    Whatever you decide on , it will need to be a good clean supply with a well maintained rail voltage, capable of delivering some serious amperage when called upon, as Dave9 says....e.x.p.e.n.s.i.v.e.!!!
    Finding out the actual maximum voltage range the amp will handle would be an advantage.
     
  13. dave9

    dave9

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    Mar 5, 2017
    I feel that I have contributed enough that this is complete. How much amperage to pay for is up to you. We, another member and I have already stated that you shouldn't need hundreds of watts.
     
    duke37 likes this.
  14. evolandlupiz`

    evolandlupiz`

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    Apr 14, 2019
    thanks everyone for the great information. i'll do some more research.
     
  15. Hopup

    Hopup

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    Jul 5, 2015
    Best way is to buy cheap PA subwoofer amplifier and hook it up to your subwoofers without any doubt. If you have proper ported box, you can get plenty of noise with much less power. Why not just sell car audio gear and buy home subwoofer?
     
  16. Audioguru

    Audioguru

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    Sep 24, 2016
    The 44Hz resonant frequency of the 12" woofer will be increased when enclosed then it will not produce sub-woofer frequencies.
    The 750W RMS into 2 ohms (both 4 ohm voice coils in parallel) output power of the amplifier has no spec's about distortion so it might produce 350W of normal sound plus another 350W of distortion. Since its frequency response is not spec'd then will it produce sub-woofer frequencies?

    Ebay sells these cheap no-name-brand items to gullible people who do not know how poorly they perform and how quickly they fail.
    How can anybody believe the spec's?
     
  17. WHONOES

    WHONOES

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    May 20, 2017
    It is quite feasible to correctly load your speaker in a properly designed enclosure to get the bass extension you seem to desire. You just need the T/S data and the appropriate sums.
     
  18. Audioguru

    Audioguru

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    Sep 24, 2016
    Parts Express 12" sub-woofers resonate at 24Hz to produce deep low frequencies. One has a max RMS power of 120W with a reasonable price and others have a 400W RMS rating and cost much more. They all have detailed T/S specs for an enclosure design.

    The very expensive high resonant frequency Chinese woofer from ebay has no detailed T/S specs then a lot of testing or trial and error is needed for an enclosure design that will not produce sub-woofer frequencies..
     
  19. WHONOES

    WHONOES

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    May 20, 2017
    Partial details for the drivers that you mention are available on their website and they even give a range of cabinet volume dimensions that could be used but the one detail they do miss out is port dimensions which are quite important so is not a lot of use.
    The better option as AG suggests is to use a different speaker for which the info is available so that the correct cabinet volume and port can be determined.
    Have a look on the Parts Express website for suitable units then, go to the link below where you can enter the Thiele-Small parameters and it will work out the cabinet volume and port dimensions.

    https://www.diyaudioandvideo.com/Calculator/SpeakerBoxEnclosure/
     
  20. Hopup

    Hopup

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    Jul 5, 2015
    Those subs won't be good for low's (sub 25hz), but they should be just fine for most music. Quality of the subs look pretty nice. Car subwoofers with their big magnets and poor sensitivity are not very good for home use if you prefer quality over quantity. Unless you have big area you should always choose smaller subwoofer with higher sensitivity to provide better dynamics.
     
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