I have a couple questions regarding the frequency response of the TH900. Please first go the link below:
http://www.headphone.com/headphones/fostex-th-900.php#tabs
Now, do you consider this a relatively "flat" impedance curve graph? For a closed dynamic headphone, that is. (I was told orthodynamic headphones generally have a flatter response)
The reason I'm asking this is because of damping factor (DF) issues. As you may know, DF is headphone impedance divided by amp's output impedance. Due to the low impedance of the TH900 at 25 ohms, it makes it difficult to obtain a high DF with this headphone unless you use a solid-state amp with very low output impedance (close to 0 ohms).
On the other hand, tube amps inherently have higher output impedance. I want to know if it's still good to use TH900 with them without causing distortions. I have a decent tube headphone amp in mind that has an output impedance of about 4.7 ohms (which is considered low for a tube amp), so the DF in this case is approximately 5.3. However, people have generally recommended a DF of 8-10 or higher.
The exception to this rule, they say, is if the headphone in question already has a relatively flat impedance curve. After all, the primary purpose of having a high DF is to achieve a flatter frequency response, and reducing distortions by doing so. But if the headphone has a flat impedance curve in the first place, the need to achieve a higher DF becomes less important. On the contrary, having a high DF would be pretty important if a headphone has very fluctuating frequency response.
From the link I provided above, do you think that the TH900 has a flat enough impedance curve to tolerate a relatively low DF of about 5 (instead of 8)? Or do you think that 5 is still not enough?
( ah the famous " OTL" v/s " Transformer coupled " battle !! )
