[FourierMakesFunk]

I finally have some time to work on the custom 'phones I've been designing for a while now. One of the last thing I have to work out is a built in switchable impedance adaptor. The drivers I'm using are the DT48E 25ohm assemblies.
 
Some people have reported using an impedance adaptor with these drivers can improve performance depending on the amp you're using (most likely due to the fact that they are designed to operate off a 120ohm impedance amp, but many amps seem to be close to 0ohm).
 
Is there any point to adding a switchable 120ohm adaptor to make them more utilitarian (able to function with more amps, since there are designed for monitoring mostly, thus I'll be plugging them into a lot of amps/sources), or possible have them switch between 0ohm, 120ohm and something like 300ohm inline resistance added?
 
Thanks!

 

[Uncle Erik]

You might want to talk to Donald North about the 0/120 Ohm issue. The Sonett lets you choose between the two and Donald has done a bit of research on the topic.

 

[FourierMakesFunk]

Just emailed Mr. North and will share his response when I get it. Any other responses are welcome of course. 

 

[FourierMakesFunk]

 
Quote:

 

Hi Colin,

Thanks for your mail. I would simply add a 100 ohm resistor in series with each driver. You can add a switch across them to bypass them. Depending on the parameters of the driver, adding the series resistor will affect the frequency response and increase the bass. You can also try different series resistors and hear which sound best to you. Of course when you do this, you need to make sure the amplifier has near 0 ohm output impedance.

Let me know if you have further questions and I'll try to help.

Best regards,
Donald