Hi,
A) I am assuming the problem manifests itself with a (brand) new battery
B) I have had a CMOY with opa2134 and while being nothing to write home about it does not distort into reasonable impedance phones (>100 ohms).
Can you tell us the type and/or impedance of your phones.
I doubt you will be able to drive Grados with a CMOY...
Best
Giulio
A) I am assuming the problem manifests itself with a (brand) new battery
B) I have had a CMOY with opa2134 and while being nothing to write home about it does not distort into reasonable impedance phones (>100 ohms).
Can you tell us the type and/or impedance of your phones.
I doubt you will be able to drive Grados with a CMOY...
Best
Giulio
Yes,
40 ohms is low and the opamp is asked to pump out more current than it is happy with. My CMOY though drove my Sony Sony MDR-EX71SLB (16 ohms) rather happily with a 100ohm series resistor on the output of the opamp.
Somebody suggested your circuit has a 75ohms series resistor on the output. If that is the case I cannot explain the difference between your and my experience.
Best
giulio
Hi PxPert,
Glad you received the chips. I sent 1x OPA2227 and 1x OPA2277, not 2x OPA2277. The numbers are similar, so you probably just assumed they were both OPA2277 at first glance. Not that it makes any difference, as I'm sure they will both perform about the same.
As I said before, you definitely need more current drive capability. I tried an OPA2134 based cmoy on low impedance phones and the results were pathetic. Putting a resistor in series didn't help at all.
I now use the OPA551 and the results are fantastic. Unfortunately the single OPA551 isn't much of an option for you. Even if you put two in a dual adapter, the +-4.5v supplied by the 9v battery isn't enough to power them properly. You would want at least +-9v.
Here is a pic of my OPA551 micro headphone amp with boost converter and discrete rail splitter......
Glad you received the chips. I sent 1x OPA2227 and 1x OPA2277, not 2x OPA2277. The numbers are similar, so you probably just assumed they were both OPA2277 at first glance. Not that it makes any difference, as I'm sure they will both perform about the same.
As I said before, you definitely need more current drive capability. I tried an OPA2134 based cmoy on low impedance phones and the results were pathetic. Putting a resistor in series didn't help at all.
I now use the OPA551 and the results are fantastic. Unfortunately the single OPA551 isn't much of an option for you. Even if you put two in a dual adapter, the +-4.5v supplied by the 9v battery isn't enough to power them properly. You would want at least +-9v.
Here is a pic of my OPA551 micro headphone amp with boost converter and discrete rail splitter......
An externally hosted image should be here but it was not working when we last tested it.
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