pawwh98
Head-Fier
- Joined
- Nov 18, 2001
- Posts
- 62
- Likes
- 0
Here it is:
It's made from a silver altoids tin, the only one kind of Altoids that seems to be available in Germany and also the most stylish tin I could find
Key Features:
1x OPA2134
2x OPA634 as output buffers
Resistors for gain and output impedance are socketed
dual feedback
added after taking these pictures:
1x BUF634 as virtual ground driver
Here is the inside (without amp module):
On the left is the battery department. It's made from plastic cut from a minidisc case and glued to the tin. On the a tiny piece of styrofoam is glued to the other side to give the Battery a tight fit.
The white rectangle in the middle is the piece of styrofoam that the amp module is placed on. This way it is isolated and fixed, and allows the remove the module easily when I want to apply changes to it.
In the middle above is the input jacket with 1 k input resistors soldered to it.
Right next are the socketed output resistors. I'm using values of 0 ohms (with beads), 47 and 120 ohms to adapt for the individual headphone used.
Below you can see the pot, it's a 10 k Radiohm stereo pot. The ground pins have a resistor wire soldered between them that I use as common ground.
Below the pot is the 'power supply', two resistors and caps soldered together and glued on the tin floor.
This is the amp module:
The big part on the left has the opamp and buffers on it, the smaller on the right the socketed resistors for gain.
The final version has another module that houses a BUF634 virtual ground driver and the 10 k voltage divider resistors. The tin is pretty stuffed now, but I'll see if I can squeeze in a acoustic simulator as next upgrade...
Here's the circuit: (sorry, handwritten)
http://home.t-online.de/home/520016954481/altoids4.jpg
Since I have very little spare time, it has taken me weeks to test, assemble and modify the amp, but it's been great fun the the result well worth the effort. The sound is plain better than any headphone output I've ever heard, and the socketed resistors make it very versatile.
These are some configurations I use:
Grado SR-60: Gain 3.3, output 0 - 120 ohms (depends on the music: 0 for instrumental/classical, 47 or 120 for pop/rock)
Sennheiser HD 560: Gain 5,7, output 120 ohms
Sony MDR-A44L: Gain 1, output 0 ohms
Sony MDR-7506: Gain 3.3, output 0 ohms
The energy consumption is about 23 mA at the moment, but I'm planning the increase the value of the bandwith resistor to increase battery life. Would 1k be a good value?
It's made from a silver altoids tin, the only one kind of Altoids that seems to be available in Germany and also the most stylish tin I could find
Key Features:
1x OPA2134
2x OPA634 as output buffers
Resistors for gain and output impedance are socketed
dual feedback
added after taking these pictures:
1x BUF634 as virtual ground driver
Here is the inside (without amp module):
On the left is the battery department. It's made from plastic cut from a minidisc case and glued to the tin. On the a tiny piece of styrofoam is glued to the other side to give the Battery a tight fit.
The white rectangle in the middle is the piece of styrofoam that the amp module is placed on. This way it is isolated and fixed, and allows the remove the module easily when I want to apply changes to it.
In the middle above is the input jacket with 1 k input resistors soldered to it.
Right next are the socketed output resistors. I'm using values of 0 ohms (with beads), 47 and 120 ohms to adapt for the individual headphone used.
Below you can see the pot, it's a 10 k Radiohm stereo pot. The ground pins have a resistor wire soldered between them that I use as common ground.
Below the pot is the 'power supply', two resistors and caps soldered together and glued on the tin floor.
This is the amp module:
The big part on the left has the opamp and buffers on it, the smaller on the right the socketed resistors for gain.
The final version has another module that houses a BUF634 virtual ground driver and the 10 k voltage divider resistors. The tin is pretty stuffed now, but I'll see if I can squeeze in a acoustic simulator as next upgrade...
Here's the circuit: (sorry, handwritten)
http://home.t-online.de/home/520016954481/altoids4.jpg
Since I have very little spare time, it has taken me weeks to test, assemble and modify the amp, but it's been great fun the the result well worth the effort. The sound is plain better than any headphone output I've ever heard, and the socketed resistors make it very versatile.
These are some configurations I use:
Grado SR-60: Gain 3.3, output 0 - 120 ohms (depends on the music: 0 for instrumental/classical, 47 or 120 for pop/rock)
Sennheiser HD 560: Gain 5,7, output 120 ohms
Sony MDR-A44L: Gain 1, output 0 ohms
Sony MDR-7506: Gain 3.3, output 0 ohms
The energy consumption is about 23 mA at the moment, but I'm planning the increase the value of the bandwith resistor to increase battery life. Would 1k be a good value?
