Symetrix 304

[StratsoundFan]

Are these specs any good? How about this: Maximum Output Level;
21 dBm, 600 Ohm load,
>6 VRMS, 200 Ohm load

 

[sergeauckland]

Those are perfectly respectable specs when driving professional headphones with a 600 ohm or higher impedance. The main issue with driving lower impedance 'consumer' type headphones is that the output impedance at 100 ohms is too high. If the headphones have an impedance characteristic that varies much with frequency, then the frequency response of the headphone will be affected. It may be worse, or indeed it could be better, but it will be different.
If, however, your headphones have a flat impedance characteristic, such as mine do, then the output impedance of 100 ohms won't matter much.

Consequently, my view is that the 304 is not a 'universal' headphone driver, you need to know what you're driving with it. Subject to that, it's fine, Symetrix products have always been decent enough 'Pro' products.

S.

 

[StratsoundFan]

My headphones are Beyerdynamic dt 990 pro 250 ohms. I have read in the manual that this amplifier is capable of driving 8-2000 ohms headphones.
I have never heard of any amp covering such wide range before.

 

[sergeauckland]

My headphones are Beyerdynamic dt 990 pro 250 ohms. I have read in the manual that this amplifier is capable of driving 8-2000 ohms headphones.
I have never heard of any amp covering such wide range before.

High impedance phones are easy to drive provided one has enough voltage output, trivially easy if the driver circuit is a small power amp. Low impedance 'phones are harder to drive again unless the driver is a small power amp. Headphones are very easy things to drive, so there's no mystique about headphone amps, or at least, there shouldn;t be.

Your Beyer headphones at 250 ohms impedance may or may not work well with the Symetrix, it depends on how the nominal 250 ohms varies with frequency, and whether the changes in frequency response that results, is an improvement or not on the headphones driven from a very low output impednace.

The way I have designed my own headphone amp is to use a 12-15 watt into 8 ohm power amp chip with good low noise, and drive the headphones with that directly. The output impedance is very low, so no variation in the frequency response, and that'll drive anything from 8 ohms upwards. Around 10v into pretty much any dynamic headphone is enough to deafen, so quite enough output.

S.