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Thread: Any one know of any good Headphone Amplifer Kits?

  1. #1
    Who am I? HiJackZX1's Avatar
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    Any one know of any good Headphone Amplifer Kits?

    I was playing with my KVMP switches and decided to test the audio aspect. It really wasnt very loud so I checked the manual. They say to get good audio, you have to use powered external speakers.

    So I was wondering if there are any good amplifier headphone kits? Another thought could be to buy some really low priced speakers and use them only for the audio booster aspect, by simply cutting the speakers off and using the headphone port. What do you guys think?

    I actually have one headphone amplifier laying around, and I did test it and it works perfectly. Thing is the cost $20.00 each and I really dont want to pay that since I need 5 more of them.

    Also if I do go the headphone amplifier route, is there a way I can power them with an external power supply, instead of using batteries?
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  2. #2
    MySQL Error soundman98's Avatar
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    check these:
    http://www.parts-express.com/pe/show...number=300-385

    i threw 2 in my cart last time i ordered from PE, and haven't had a chance to try them out, but the reviews are good, and they are some of the cheapest cost, prebuilt amps i have seen..

  3. #3
    Who am I? HiJackZX1's Avatar
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    Thanks. I didnt see these when I was browsing PE. This looks like they might do the trick. All six will only cost me about $120 bucks, which isbt bad. What I like is that these are powered by external, and not a battery. All I have to do is figure out how to get regulated 12V power to them.
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    Raw Wave
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    For headphones? 15W! (Unless several headphones... - like at least 6!)

  5. #5
    Who am I? HiJackZX1's Avatar
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    Quote Originally Posted by OldSpark View Post
    For headphones? 15W! (Unless several headphones... - like at least 6!)
    LMFAO, maybe if I explain. When i tested the KVMP switches audio sounded good, but there was a weird crackle in the background. It was loud enough to drive me insane. When I put the headphone amp that I had laying around, on the outport of the KVMP, the sound was crystal clear.

    If that is too much, what do you recommend. I saw these http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWAX:IT Only thing I hate is that they use batteries. Unless I can find anotehr way to power them.
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  6. #6
    Who am I? HiJackZX1's Avatar
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    OK, I bought 6 of the audio amps I linked to. It uses a single AAA battery, so that means these units run on 1.5V. I have a power regulator that puts out 1.5V. Do you think these things use a lot of amps? That way I can just tie them all to be powered by the regulator? The adapter has a max of 2000ma.
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  7. #7
    Raw Wave
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    I reckon 4 units at MAX power each (conservatively(?) - later, below), hence 6 is probably ok.

    I reckon measure the current from the battery using a DMM (full or max "practicable" volume into lowest impedance headphones).


    I assume it's a switching regulator you have? If so, it should be self limiting (most if mot all SMPS chips have current limiting functionality) so overloads shouldn't harm it (if say all 6 amps at max 500mA each went to full volume).
    And the amps shouldn't be damaged since they could be using flatteries



    I'd assume the noise or crackle is impedance mismatching else ground loops....
    If it's KVM to headphones, isn't that (say) 1k or 10kR to 8R? (1k:8 transformers could fix that - not that I think the KVM is/was driving the headphones directly...)

    And FTR, I checked kvmP - I assumed it was just a KVM. It seems to be, but with added USB (which could select instead of the kyb etc) so my ramchings (rambling preachings) should still be valid.
    (So it's kvm & Peripherals; why not kvmu or kvum - they're all bluddy peripherals! And don't mention Control!)


    FYI - The insanity behind my power/current calcs:
    8-Ohm headphones suggests a max of VV/R = 1.5 x 1.5 /8 = .3W or 1.5/8 = 0.2A (output)
    So - assuming no internal transformers etc (for voltage step-up from 1.5V) & 8R phones; 200mA max output per channel x2 = 400mA plus (say) 25% inefficiency = 500mA.

    [ FYI - Why did I chose 25%? 500mA is a nice round number and seems familiar. (LOL - USB). Big amps are usually >85% efficient, but small power amps usually real bad. However, only OpAmp chips or tranies etc, they can be extremely efficient.
    I'm also wondering if the current could be double my guessticalcumate - the answer to that is so simple and basic that I haven't a clue.
    Conclusion: DMM! ]


    TRIVIAL bonus piece:
    Will a 1.5V battery "clicked" to a speaker to test polarity cause damage.
    Assume 1R speaker. Power P = VV/R = 1.5 x 1.5 /1 = 2.25.
    So if a 1 Ohm (car) speaker is more than 3W (even 2W), then NO, battery will not damage (unless left connected).
    Apols, but that little ramching had often killed pages of debate and surveys.
    & a 9V battery? 9x9/1 = 81 -> ~ 80W (but only for a short "click"...)

  8. #8
    Who am I? HiJackZX1's Avatar
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    OK, I got the AMPS in today. They came from Taiwan. First thing I noticed is that these things are very small. Second is that they are made of very high quality plastics.

    The bad news, these things do not seem to have an on and off switch. Instead it works by turning on when a headphone is plugged into the port. I dont think its a big deal. I decided to test the unit out and I have to say, these things pack a punch. I turned all the way up and there was very little distortion.

    Only thing to do now is hope they will work with the mod I want to do.

    I do have a question though. Now because I am putting these devices in series, doesnt that mean i have to step up the voltage?

    So say 1.5V x 6 = 9V.... Or is my thinking incorrect? Should I only be looking at amps?
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    MySQL Error soundman98's Avatar
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    why series? that is going to be one common failure point.. i would prefer parallel for something like that--that way, if anything happens to one amp, at least the rest still work..

    otherwise(wheather you choose to connect everything in series or parallel), i believe your only need to worry about keeping the input voltage around 1.5v, and the current is going to be larger..

  10. #10
    Raw Wave
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    Are they floating ground? If not, series is not an option.

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