[Fenster]

A couple of weeks ago I bought a corda blue from someone here in the forums and it sounds great.

I've been using the grado SR225's with it, and I find myself using the 120 Ohm jack instead of the standard 0 Ohm jack. For some reason it just sounds better to me this way. Out of the 0 Ohm jack everything sounds overly bright and scratchy-sounding. Not only that, but everything improves when I switch to the 120 Ohm jack, like bass, smoothness, and even soundstage. It's almost like the 120 Ohm jack tames the 225's just perfectly. Out of the 0 Ohm jack everything's a sloppy, shrill mess. And out of the 120 Ohm jack they are beautifully balanced.

Anyone else find this beneficial to their phones, or am I the only one?

 

[Guyferd]

It's been said that bright headphones are good out of the 120 ohm. cans like 931, grados are usually much better out of the corda's 120 ohm jack.
But I am using 0 ohm for my 880. Has more speed and microdynamics

 

[Rameish]

120 ohm is definately better for Grados - as a former Grado and Corda dealer I should know. This is true of the whole line of Corda amps. Other headphones that benefit from the 120 ohm output jack are:

All current day Grados, Beyer DT 931, DT 831, DT-48, Ety 4P. You may wish to try making an impedence adapter with 2 resistors in the male jack portion. In which case use the 0 ohm jack. Generally goinging beyond 3 times the impedence of the cans does nothing more than provide attnuation. Jan Meier covers this more in his website. There's lots to leans from Jan.

Happy listening

 

[Anders]

Rameish, thanks for that! I recently got a Prehead and never though 120 ohm something for Grados, placing them in some low-impedance category. I made a fast one-track test and this seems promising.

 

[Rameish]

Anders,

No problem. So with a grado headphone (32 ohm) going beyond 96 ohms isn't going to change the sound or at least it shouldn't and not to my ears. Like I said, for the more technically minded, please visit Meier Audio.

Happy Listening

 

[JaZZ]

It's somewhat astonishing how a headphone with such an impedance curve...

...can be affected by a serial resistance. Well, it's not completely flat, and the resistance surpassing 4 times the nominal impedance... Imagine an EQ curve with the shape of the one above.

 

[Anders]

I used a SR225!
I tried a track on another record and still think there is a difference, although subtle. This is a preliminary impression and there are some problems with such comparisons as keeping a constant volume. I will return to istening some later time when I feel more relaxed and attuned to this.
Do you mean that a serial impedance should have no effect if the impedance curve is absolutely flat? There is a variation between about 30 - 40 ohm in the curve but I don't know what that means in relation to a measurable change of the frequency curve.

 

[JaZZ]

Anders...
Quote:

Do you mean that a serial impedance should have no effect if the impedance curve is absolutely flat?

Yes, roughly spoken. Except for cases where the amp's output impedance itself varies with frequency, and of course when the amp is forced to work in a dynamic range where it produces considerably higher harmonic distortion.

It's easy to understand: The lower the driver impedance, the more attenuation caused by a given resistance. So the bass-resonance hump marks a frequency range where the attenuation is reduced compared to the midrange; the same applies to a possible rise towards the upper end. A 32 ohm resistance in series to a 32-ohm headphone means an attenuation of 3 dB, whereas the (virtual) 64-dB bass-resonance hump is attenuated by only 1.5 dB.

 

[Anders]

Hope I have understood this correctly. I looked at the formula at Jan Meiers homepage and made some calculations based on Headroom's impedance curves. Then I looked at the lowest and highest impedances for DT931 and SR225. The latter is inexact because the scale is too gross for this, I estimated figures of roughly 30 and 40 ohm for SR225 but the real difference may be slightly less and I will use 32 and 40 ohm.

With a 120 ohm resistor in series with the headphone I get max and min attenuation values for DT931 of 0.85 and 0.65 (meaning that at the first point the signal is 0.85 of the level without resistor). The values for SR225 are 0.25 and 0.21. This should mean that the change in frequency balance is less for SR225, about half of that for DT931, but not neglible. Or did I miss something? Anyway, it was fun to dig a little deeper into this.

 

[JaZZ]

Anders...
Quote:

With a 120 ohm resistor in series with the headphone I get max and min attenuation values for DT931 of 0.85 and 0.65 (meaning that at the first point the signal is 0.85 of the level without resistor). The values for SR225 are 0.25 and 0.21. This should mean that the change in frequency balance is less for SR225, about half of that for DT931, but not neglible. Or did I miss something?

No, this sounds plausible. Despite its much lower impedance the impact from the serial resistor on the SR-225's frequency response is smaller because of its outstandingly flat impedance response.