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Any one know of any good Headphone Amplifer Kits?

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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
    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..
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    • #3
      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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      • #4
        For headphones? 15W! (Unless several headphones... - like at least 6!)

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        • #5
          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
            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
              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"...)

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              • #8
                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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                • #9
                  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..
                  My OLD 2001 Mitsubishi Eclipse GT:
                  "The Project That Never Ended, until it did"


                  next project? subaru brz
                  carpc undecided

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

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                    • #11
                      Originally posted by soundman98 View Post
                      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..
                      Well I figured it would be easier. So the best thing to do is have each individually connect to the PSU?

                      Originally posted by OldSpark View Post
                      Are they floating ground? If not, series is not an option.
                      What is a floating ground?
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                      • #12
                        Floating - chances are that the ground/common for the input or output is also the PSU/battery ground. Hence the input/output ground(s) are not "floating".

                        If not floating, the grounds will be 1.5V apart. Hence they will "short" when "grounded" (ie, short circuited).

                        Besides, connecting 6 1.5V powered devices in series is not the same as having a 9V supply equally split into 4. You could have one amp blow at 4V etc.... (and then avalanche or total failure as soundman98 suggested).


                        The bottom line - if they are not "floating" grounds (so that grounds can be commoned together), then their power must be connected in parallel (so that they all have the same ground).

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                        • #13
                          Thanx for all the help guys. Here is the final finished product.



                          They all meet up at one ground point, and one 1.5V point. Tested them all and they are working perfectly.

                          Looks like I'm getting closer to finishing my install.
                          Nirwana Project, the Android/Win 7 hybrid system!

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