j-curve
100+ Head-Fier
- Joined
- Apr 15, 2002
- Posts
- 489
- Likes
- 11
I built my first headphone amp the other day, based on a kit published by Silicon Chip, an Australian electronics magazine. Mine is modified for zero output impedance. Let's call it the MSCA - Modified "Silicon Chip" Amp, although I would never try to modify a silicon chip at home.
The first time I listened to the MSCA I was blown away by the improvement in lower midrange detail I was getting from the HD580. Recently I've been driving the phones straight from the front panel of a Yamaha CDX-510 CD player, which sounds pretty good but has an output impedance of 78 ohms.
So far so good. To get a better idea of any benefits the new amp was providing I set up an A/B test against the Yamaha's built-in amp. The main difference was again the added detail in the mid-bass, extending up into the vocal range as well. However, the Yamaha amp seemed to be providing slightly more volume of bass, even when I drove the MSCA from the Yamaha's headphone output instead of the line output. This meant that the difference couldn't be due to any "dumb-bass" effect built into the Yamaha amp. This had me worried since the MSCA is supposed to be flat to 20Hz (well, 0.8dB down to be precise). I measured the MSCA and it was exactly on specification.
This leads me to the conlcusion that the higher output impedance of the Yamaha amp provides insufficient damping to the transducers, resulting in loose or flabby bass which may sound louder but is less accurate and detailed. I had read about the benefits to the HD580 of using a low output impedance before but I always assumed the difference would be at higher frequencies. Now I think it's more to do with the fundamental resonance of the driver around 110 Hz.
With the MSCA the HD580 bass hump has gone and the sound is cleaner. How happy do I need to be?
The first time I listened to the MSCA I was blown away by the improvement in lower midrange detail I was getting from the HD580. Recently I've been driving the phones straight from the front panel of a Yamaha CDX-510 CD player, which sounds pretty good but has an output impedance of 78 ohms.
So far so good. To get a better idea of any benefits the new amp was providing I set up an A/B test against the Yamaha's built-in amp. The main difference was again the added detail in the mid-bass, extending up into the vocal range as well. However, the Yamaha amp seemed to be providing slightly more volume of bass, even when I drove the MSCA from the Yamaha's headphone output instead of the line output. This meant that the difference couldn't be due to any "dumb-bass" effect built into the Yamaha amp. This had me worried since the MSCA is supposed to be flat to 20Hz (well, 0.8dB down to be precise). I measured the MSCA and it was exactly on specification.
This leads me to the conlcusion that the higher output impedance of the Yamaha amp provides insufficient damping to the transducers, resulting in loose or flabby bass which may sound louder but is less accurate and detailed. I had read about the benefits to the HD580 of using a low output impedance before but I always assumed the difference would be at higher frequencies. Now I think it's more to do with the fundamental resonance of the driver around 110 Hz.
With the MSCA the HD580 bass hump has gone and the sound is cleaner. How happy do I need to be?
