Hello all,
I am new here, and I hope that I am posting this in the right forum.
As for Intros, I live in the Detroit area. Like to tinker with tube audio as a hobby.
I own two KOSS A-1220 headphone amps. Each share the same model number, yet have completely different internals: One uses just a single 12AU7, while the other has a 12AT7 and a pair of 6AQ5A's.
I have recapped each of them and they sound 'ok'. The problem I am having is that there is little to no bass present (in each unit). And there is a slight hum in the background.
My first goal is to find a way to adjust the EQ circuit and get more low end. *note that neither of these units have tone controls.
From what I have read online, you can sometimes adjust filter caps to get different tone, correct?
Here is the schematic for the single tube version. Does anyone have any suggestions on what I can do to get a better sound?
Many thanks.
[IMGDEAD]https://i9.photobucket.com/albums/a60/darmen/Koss1schematic_zpscf357a61.jpeg[/IMGDEAD]
I am new here, and I hope that I am posting this in the right forum.
As for Intros, I live in the Detroit area. Like to tinker with tube audio as a hobby.
I own two KOSS A-1220 headphone amps. Each share the same model number, yet have completely different internals: One uses just a single 12AU7, while the other has a 12AT7 and a pair of 6AQ5A's.
I have recapped each of them and they sound 'ok'. The problem I am having is that there is little to no bass present (in each unit). And there is a slight hum in the background.
My first goal is to find a way to adjust the EQ circuit and get more low end. *note that neither of these units have tone controls.
From what I have read online, you can sometimes adjust filter caps to get different tone, correct?
Here is the schematic for the single tube version. Does anyone have any suggestions on what I can do to get a better sound?
Many thanks.
[IMGDEAD]https://i9.photobucket.com/albums/a60/darmen/Koss1schematic_zpscf357a61.jpeg[/IMGDEAD]