Hi together,
I just recently started building loudspeakers and amps myself, am new to soldering, still learning about resistors and all these kinds of things and am little bit stuck with a problem.
I have a 2A3 SET tube amp for which I built an amp-to-headphone adapter based on https://robrobinette.com/HeadphoneResistorNetworkCalculator.htm respectively https://robrobinette.com/images/Audio/Headphone_Resistor_Network_Calculator.xls, using the "Three Resistor Network" as that gave me the best values for the load on the amp, attenuation and damping factor. I added two of these with a switch, so I can toggle between them for different sound flavors as well as using it for headphones with different impedances (I have ZMF headphones with 60 ohm and 300 ohm).
For both networks, the load on the amp is around 8 ohm (which the amp is designed for) and the attenuation is almost exactly the same.
Depending on which headphones I use, the damping factors are 1:4 and 1:19 (the 60 ohm headphones) respectively 1:44 and 1:223 (the 300 ohm headphones).
Now, my understanding is that a very low damping factor like 1:4 should give me a bit more boomier bass which is less precise, because the amp is not able to control the driver that well. Other than that I would not expect too much audible differences.
However for both headphones the setting with the lower damping factor leads to much worse sound quality. The soundstage collapses, it becomes very noticeably less wide and everything sounds a little bit less clear. Somehow much cheaper. It is the same on both channels and it has nothing to do with the volume.
I am using MOX resistors everywhere and from what I can tell everything measures fine (the resistances I measure are consistent everywhere, I don't see anything that seems odd). I bought most of the resistors at a local store and I don't know how old they were. They might have been lying there for a while.
Can you help me figuring out what the issue could be? Might some resistors be too old for example? Could I measure anything else besides the resistances in the circuit? The circuit itself does not seem to be the problem as the setting with the higher damping factor sounds pretty good.
I am very confused as both headphones usually sound fabulous, but really cheap with that one setting…
Thanks a lot!
Michael
PS: Sorry if used wrong terms or weird language. As I said, still new to all this 🙂
I just recently started building loudspeakers and amps myself, am new to soldering, still learning about resistors and all these kinds of things and am little bit stuck with a problem.
I have a 2A3 SET tube amp for which I built an amp-to-headphone adapter based on https://robrobinette.com/HeadphoneResistorNetworkCalculator.htm respectively https://robrobinette.com/images/Audio/Headphone_Resistor_Network_Calculator.xls, using the "Three Resistor Network" as that gave me the best values for the load on the amp, attenuation and damping factor. I added two of these with a switch, so I can toggle between them for different sound flavors as well as using it for headphones with different impedances (I have ZMF headphones with 60 ohm and 300 ohm).
For both networks, the load on the amp is around 8 ohm (which the amp is designed for) and the attenuation is almost exactly the same.
Depending on which headphones I use, the damping factors are 1:4 and 1:19 (the 60 ohm headphones) respectively 1:44 and 1:223 (the 300 ohm headphones).
Now, my understanding is that a very low damping factor like 1:4 should give me a bit more boomier bass which is less precise, because the amp is not able to control the driver that well. Other than that I would not expect too much audible differences.
However for both headphones the setting with the lower damping factor leads to much worse sound quality. The soundstage collapses, it becomes very noticeably less wide and everything sounds a little bit less clear. Somehow much cheaper. It is the same on both channels and it has nothing to do with the volume.
I am using MOX resistors everywhere and from what I can tell everything measures fine (the resistances I measure are consistent everywhere, I don't see anything that seems odd). I bought most of the resistors at a local store and I don't know how old they were. They might have been lying there for a while.
Can you help me figuring out what the issue could be? Might some resistors be too old for example? Could I measure anything else besides the resistances in the circuit? The circuit itself does not seem to be the problem as the setting with the higher damping factor sounds pretty good.
I am very confused as both headphones usually sound fabulous, but really cheap with that one setting…
Thanks a lot!
Michael
PS: Sorry if used wrong terms or weird language. As I said, still new to all this 🙂
Attachments
Although your project is tube based and this writeup is for transitor / opamp based h/p amp, still a good read
https://benchmarkmedia.com/blogs/application_notes/12838141-headphone-amplifiers-part-1
https://benchmarkmedia.com/blogs/application_notes/12838141-headphone-amplifiers-part-1
Thank you, @availlyrics, but I am afraid it has nothing to do with that. I realized that the circuit creates a lot of crosstalk. And it's much worse for one setting because of a much lower resistor value. At least I think that's what it is…