Just about the only way to improve on <a href="http://www.diyaudio.com/forums/showthread.php?s=&threadid=2451">tortello's beautiful Zen headphone amp</a> is to go for an Aleph headphone amp. The advantages are the balanced FET front-end and the DC-coupled output. This design is specified to put 500mW into Grado headphones, or other phones with about 32Ω impedance. It should also drive a small speaker, and indeed has done so in a breadboard incarnation.
Right now the only thing I'm not liking is the high value of the current sense resistor. I used it in my breadboard mockup but I might change it for something smaller.
One channel shown.
Right now the only thing I'm not liking is the high value of the current sense resistor. I used it in my breadboard mockup but I might change it for something smaller.
One channel shown.
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Re: Missing component ?
All that junk on the left is for the input coupling. I didn't draw it because it isn't that interesting.
Nicke said:Shouldn´t there be a resistor between R14 & R15 coupled to ground ?
All that junk on the left is for the input coupling. I didn't draw it because it isn't that interesting.
Re: Missing component ?
What Nicke means is, you're showing 100% feedback. A resistor where he suggests would reduce feedback, adding actual gain.Nicke said:Shouldn´t there be a resistor between R14 & R15 coupled to ground ?
Nicke
Re: Re: Missing component ?
Thats right ...
Is it unity gain stable as drawn ?
paulb said:
What Nicke means is, you're showing 100% feedback. A resistor where he suggests would reduce feedback, adding actual gain.
Thats right ...
Is it unity gain stable as drawn ?
jwb said:Hi Edwin. It's going well. I got a Sun 411 SCSI case to put the amp in and modified it for XLR connectors. I'm still in the process of drawing the printed circuit board. Hopefully I will finish it next weekend.
I also increased the design rail voltage to 14V.
Did you listen to it? How does it sound? What did you use before building this Aleph headphone amp?
Edwin
Re: Powersupply
I have listened to one channel on a breadboard. It sounds rather bad! But it is powerful and the bad sound is a result of poor layout, I hope.
My previous headphone amp was the Sheldon Stokes design seen on Headwize.
I am using four separate Sulzer regulators with AD797 error amp and ZTX869 for the pass transistor. The power dissipation is low enough to not require a big power transistor.
Cheers
Edwin Dorre said:
Did you listen to it? How does it sound? What did you use before building this Aleph headphone amp?
I have listened to one channel on a breadboard. It sounds rather bad! But it is powerful and the bad sound is a result of poor layout, I hope.
My previous headphone amp was the Sheldon Stokes design seen on Headwize.
swede said:So, how about the PS?
Are you going for an unregulated supply, or are you using a regulated?
I've been schetching on a regulated PS based on the circuit explained in the A75 article part 2, which I will use for my Aleph headphone amp.
I am using four separate Sulzer regulators with AD797 error amp and ZTX869 for the pass transistor. The power dissipation is low enough to not require a big power transistor.
Cheers
Case finished
These Sun 411 SCSI cases are awesome for audio projects. The SCSI connector cutout is just the right size for two Neutrik XLR jacks. And, the case comes fully shielded contains a switched, fused power entry module. What more could I ask for?
These Sun 411 SCSI cases are awesome for audio projects. The SCSI connector cutout is just the right size for two Neutrik XLR jacks. And, the case comes fully shielded contains a switched, fused power entry module. What more could I ask for?
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