How can an amp be tested for function?

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broguearcher
broguearcher Posts: 28
edited April 2006 in Car Audio & Electronics
What options are there for testing the output of an amplifier in order to determine if it's functioning correctly? Simple AC/DC voltage meter?

I believe that my amplifier is passing on distortion to my sub. Can this be verified in some way?
Post edited by broguearcher on
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  • neomagus00
    neomagus00 Posts: 3,899
    edited April 2006
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    hmm... theoretically, you could calculate the expected output voltage and then measure that, but that would be insanely difficult and have a huge error...

    to check an AMP for distortion probably requires an oscilloscope, unfortunately... you may wish to ask your local community college if you can borrow one of theirs :p

    have you narrowed the problem down to definitely the amp?
    It's not good, very fundamentally simply not good. - geolemon

    "Its not good enough until we have real-time fearmongering. I want my fear mongered as it happens." - Shizelbs
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  • broguearcher
    broguearcher Posts: 28
    edited April 2006
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    I have not determined that the amp is for certain at fault but it seems likely. I've tried two different 10" MOMO subs on it and I am getting the same sound/result with them.
    neomagus00 wrote:
    hmm... theoretically, you could calculate the expected output voltage and then measure that, but that would be insanely difficult and have a huge error...

    to check an AMP for distortion probably requires an oscilloscope, unfortunately... you may wish to ask your local community college if you can borrow one of theirs :p

    have you narrowed the problem down to definitely the amp?
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  • Greg Peters
    Greg Peters Posts: 605
    edited April 2006
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    Is your system all tried and true (without previous distortion) before the addition of your sub amp in question?

    It would be easier to pin down knowing what components you are using for everything, but if your amp in question is putting out clean power within the ideal range for your Momo 10", and your sub enclosure is within the specifications provided by Polk for that woofer, all should be well.

    Some brands of amplifiers are known to be improperly rated as to power output, and some are known to provide a higher amount of distortion in the signal as well. If your amp runs out of headroom due to its design, or even if it cannot properly make its rated power due to faults in your vehicle's electrical system, distortion can result.

    Ported and sealed sub enclosures will give different results with a given woofer, both with some trade-offs. A sealed box requires more power for higher output, and a ported box requires less but will not control the woofer as tightly across the whole spectrum of bass frequencies. An air leak in your enclosure can effect subwoofer output and sound quality as well. If anything is not ideal in the relationship between your sub, its enclosure, and the amplifier powering it, you can get some distortion in the mix.

    Distortion can come from a number of things- the amp may be a good place to start, but by no means is it the only place to look.
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  • Greg Peters
    Greg Peters Posts: 605
    edited April 2006
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    Actually, I read your other thread...

    http://www.polkaudio.com/forums/showthread.php?t=40071

    Don't bother to spend money testing this amplifier. It cannot do justice to any Polk Momo subwoofer. The amp will be the cause of your distortion.

    While you may not like the answers (due to $$$), post a thread asking for suitable amps to power your new Momo 10" and then save up.
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  • MacLeod
    MacLeod Posts: 14,358
    edited April 2006
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    Chances are that since the amp is cheap and low powered, youve got the gain set too high and are pushing it into clipping which is sending out the distorted signal to the sub and thats what youre hearing. Youd be much better off buying a proper amp that can make the proper power.
    polkaudio sound quality competitor since 2005
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  • 1996blackmax
    1996blackmax Posts: 2,436
    edited April 2006
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    Time for an upgrade......... :)
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  • broguearcher
    broguearcher Posts: 28
    edited April 2006
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    1996blackmax wrote:
    Time for an upgrade......... :)


    oh, I know... completely agree. I was never looking for much of anything really in terms of performance. Just a little bass was fine...... now, I'm all wrapped up in this and want the best set up that I'm able to get for the money and I want the equipment to work right as well.
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  • 98thumpin
    98thumpin Posts: 649
    edited April 2006
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    id ditch that cheap amp and get a better one for the momo sub, the amp is your problem
    John Tyler Birch

    home audio system:

    Denon avr-1907
    Sony dvd/cd changer 5 disc
    nakamichi BX-100 tape deck
    2 Polk Audio monitor 70's
    Velodyne DPS-12 subwoofer
    RCA TV
    NAK 600 tape deck
    Monster power line conditioning power center
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  • broguearcher
    broguearcher Posts: 28
    edited April 2006
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    98thumpin wrote:
    id ditch that cheap amp and get a better one for the momo sub, the amp is your problem


    agreed..... I'm working on that issue at the moment.
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  • Stroker
    Stroker Posts: 30
    edited April 2006
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    Hey I have a polk c500.1 mono sub amp.. very very clean and in good shape. only 6 month's old. I'd sell it for $300 if you want.. Cheaper then buying it new.
    88 Wrangler 383 stroker 525hp 10 inch's of lift 38.5's
    Premier 860mp 140 & 200 amp altenator
    MMC6500 driven vy c300.2
    MMC690 driven by c300.2
    2-MM2104's driven by c500.1
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  • deepinya
    deepinya Posts: 199
    edited April 2006
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    You can buy em new for less than $300.....if you know what you are doing.

    $200 would be a deal!
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  • PoweredByDodge
    PoweredByDodge Posts: 4,185
    edited April 2006
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    Actually Lightning Audio Strike and Storm series amplifiers aren't bad at all...they're quite nice in fact. Very reliable, extremely potent and robust. A bit on the warm side in my opinion, but most come with built in fans...

    The Bolt series isn't really worth much though -- they're 'Best Buy' / 'Walmart' type amps... they're not junk... but they're not the creme de le creme by any means...

    What I'm trying to say is that - normally driven within its means - a Bolt amp should not produce any more distortion than any other respectable amplifier. I agree with previous posters that you are probably driving this amp well beyond its rated output power and thus trying to get blood from a stone, throwing it into clipping like crazy.
    The Artist formerly known as PoweredByDodge
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