[tapeholder]

I have a Firestone Audio Cute Beyond headphone amplifier. It is the "newer" model, which has been available for a couple of years already I think. It has a 6,3 mm (1/4") headphone connector and, according to the specs, an OPA2604.

The specs do not tell what is the output impedance (which is a shame, all headphone amps should have their output impedance listed). By searching around the internet , I have seen a mention of a below 1 ohm output impedance on the Cute Beyond, but it seems like that information could be from the specs of the old version of Cute Beyond.

Does anyone have reliable (e.g. self-measured, or reliable source) information of what is the output impedance of the "new" Cute Beyond headphone amp?



I would want to know that because I am planning to buy Beyerdynamic DT 770 Pro, and the amplifier's output impedance would pretty much determine whether I choose the 80 ohm or 250 ohm version. I would prefer the 80 ohm version, but if the Cute Beyond has too high output impedance, the damping factor wouldn't be ideal, in which case I would probably take the 250 ohm one.

 

[tapeholder]

The output impedance of Firestone Audio Cute Beyond is less than 1 ohm. I ended up measuring it myself to get peace of mind.
 
The output impedance varied between ~0.05 ohms and ~0.5 ohms, depending on the output load and volume/gain setting.
 
At very high volume settings the output impedance was closer to 1 ohm, but that result is not necessarily reliable because it's possible the amplifier's output was getting distorted (I can't confirm that because I didn't have an oscilloscope), and that's not even relevant for typical headphones, because at those volume levels either the headphones or hearing would be damaged.
 
So that's rather good news. At least damping factor won't be an issue with the Cute Beyond.

 

[Headdie]

I had the same question for the Cute Curve.
 
I found that on the net, but wasn't sure of the reliability,

[td] Output Resistance:[/td] [td] » Extra low output resistance (Zo < 0.05 ohms),high current capacity[/td]

 
Do you think that output impedance can change when the volume is set to shunt mode ?
 
Also, I've got improvement changing the wallwart and the OPA2604.
 
Regards,

 

[tapeholder]

I don't know can the volume's shunt mode affect output impedance, but I would guess not, or at least not much. I probably won't open my Cute Beyond, so I can't test that.