Ducker
Head-Fier
- Joined
- Feb 7, 2010
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How so?
You may not need any parallel resistor at the amp terminals as these are all relatively low impedance headphones. With the lower sensitivity headphones you would be throwing a lot of energy away through a parallel resistor.
However, that is a wide range in sensitivities. Especially for those real efficient cans you may need a series resistor at the amp, a parallel resistor after that, and another series resistor before the headphones, like that voltage divider circuit a prior poster gave a link to. I'd be careful with those 102 and especially 108db cans, not to blow them up with a speaker amp. I personally would not be hooking them up without resistive loading.
I would start with a 10 ohm 5 watt resistor in parallel (going from + to -) and a 20 or 25 ohm 5 watt resistor in series, after the 10 ohm resistor, in the + line. Feel the resistors to see if they start getting real hot in use. If so up the wattage.
Some will bemoan the 25 ohm resistor, saying damping factor will only be 2. My experience says try it anyway. I have no damping factor on my current setup with the Senn HD800 as my series loading resistors are so high, yet the sound is very detailed, and bass is explosive, just the opposite of what we might think a low damping factor would give. This parallels my experience with speakers and amps, depending on the Q of the speaker and the characteristics of the amp one can have more explosive sound than a much higher damping factor amp that does not mate up as well with the speaker. The moral is: you MUST try these things to know for sure.
If you end up feeling bass is softer or less powerful you could try a 10 ohm series resistor. These are not expensive, non-inductive Vishay-Dale wire wound resistors (I am finding these sound great in this application, though I am sure I'll be preached to saying I should use Mundorf or something even more exotic) cost $2-$5 each from Mouser in these sizes.
Please let us know the results.
I would start with a 10 ohm 5 watt resistor in parallel (going from + to -) and a 20 or 25 ohm 5 watt resistor in series, after the 10 ohm resistor, in the + line. Feel the resistors to see if they start getting real hot in use. If so up the wattage.
Do you always disconnect the headphones before starting or shutting off the amplifier?
Very interesting thread! I have the 600 ohm version of Beyerdynamic DT 880's. Do the above recommended resistor values stay the same? Thanks!
Personally, no. It's a risk that when the Amp is running that you'll accidentally short the + and - terminals together and damage the amp.
One thing I always do (even with regular headamp) is the turn the Volume to mute before power up/down.
On the headphone end of the cable there wouldn´t be a problem or? I am thinking speaker amps may be even worse then some headphone amps on startup or shut down. I am not going to let my receiver run 24/7. Some designs like the SPL auditor/phonitor and the Lyr before they fix that issues for example wasn´t nice to headphones on startup.
I am only going to use my ortho which I imagine tolerate a bit more then dynamic drivers though.
Using a XLR connector mid cable gives you the ability to disconnect the phones without messing with the posts.Personally, no. It's a risk that when the Amp is running that you'll accidentally short the + and - terminals together and damage the amp.
One thing I always do (even with regular headamp) is the turn the Volume to mute before power up/down.