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2*400 Ohm headphones - Can't get enough amplification...

Hi there! I am an owner of the Beyerdynamic DT 100 headphones. These headphones feature 2*400 ohm resistance on each speaker (2 speakers of 400 ohm each on each ear). Since I can't get enough amplification on these headphones, does anyone know if there is a way to change the resistance through any external device? I know that the speaker resistance is a variable - according to the frequency - impendance but is there any possible solution to this problem I am facing? Even a fixed headphone amp suggested would be helpful...
Thanx beforehand ,

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  • MUSICTRACER Oct 17, 2008

    Thanx a lot robotek. I don't think I could get any more accurate answer. The fact is that building my own amp is a very suggestive solution, but though I am studying music technology (which includes electronics) I wouldn't like to mess with circuit implementation.
    The table you link me to on the other hand is a quite powerful solution. But what I would like to know is if I can calculate the power I can get on my headphones, when amp is turned all the way up - given the amp output impendance, the maximum amplification level and generally anything that I could find on the product specs. Oh... and another question : The dt 100 - which I agree that are great and beautiful and that's why I am trying to find a way to make them work for me rather than sell them - they feature 2 speakers of 400 ohm each for every channel. Does this mean they are parallel connected, so that the channel impendance is 1/Rch = 1/R1 + 1/R2 ?
    And how important is the matching of phones impentance with the amp out impendance? As far as I know, one can draw too much current for the other to handle and vice versa, thus causing damage...

    Thanx once again for your assistance,

  • MUSICTRACER Oct 18, 2008

    Thanx a lot once again for your assistance and your quick response robotek. Well the reason why I am asking for the impedance matching isn't of course for trying to get more amplification. I would just like to know how important it is for not causing damage to any of the components (headphone - amp). I know about the 3dB of amplification that comes out of the 10log2/1, that's not my point.
    What I'm trying to find is mathimatical equations that could help me calculate the power I can get on my headphones, when amp is
    turned all the way up - given the amp output impendance, the maximum
    amplification level and generally anything that I could find on the
    product specs. I checked the DT100 impendance with a multimeter which displayed 406 ohm per channel. But how can that be when there are two speakers of 400 ohm on every channel - There is no doubt for what I'm telling you: On every side of the phones is sculted "2*400". If these were parallel, the multimeter should display 200ohm, shouldn't it?
    I also found another thing in specs.... What is the difference between nominal spl ("94 dBspl") and input power rating ("1000mw = 124dBspl") ?
    thanx again,


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You have an excellent pair of cans there, considered by many as a good industry standard for closed ear monitors. High SPL ability and good sensitivity make me think the problem you have is related more to how you are driving them. "rewiring" them as such is not really a solution to the problem you have. What you need to be looking for is more voltage across them, not lower impedance. I personally built my own headphone amps for my studio, decided to do this because i could not get the levels needed to satisfy deaf drummers and Marshall stack guitarists :).

Depending on your budget, there are many types of headphone amps on the market to choose from. You could build this one yourself the "headbanger" high output headphone amp if it is high levels you are after, or go for a commercial one at great not great expense, however they may not provide the levels it sounds like you are looking for. Check here for some makes and models of different price ranges. You can source most of these products anywhere in the world, I have given you a site in Australia, but there are many wholesale type music gear suppliers about that can give you a good deal. If you need more information. happy to answer questions.

A FixYa rating is a great reward for this info to you. Cheers


Posted on Oct 17, 2008

  • Graeme Ross
    Graeme Ross Oct 17, 2008

    The problem you face is quite a common one if you are looking for high levels from a headphone because some headphone amp stages do not have alot of power output available. You have the formula correct for calculating resistance in parallel, however, as I mentioned you are trying to get more power (watts) into the cans. Halving the the impedance in effect will not double the loudness of the cans as sound works on a log scale. So to be twice as loud(3dB) so to speak, you need 10 times the power. In this case, halving the impedance will not give you this. I have looked about the Web, and while not having used the DT100's before, they are from a good company, and generally respected as a good product. But I could not find any reference to them using 2 drivers per can(4 in total) as you mentioned. I even checked the Beyer site Even if so(they have 4 drivers) halving the impedance of them would not give you much increase in loudness anyways, whereas a headphone amp can find you up to 20 dB of gain to your standard H/P output. That would make them VERY MUCH louder.


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