You're right, I didn't need that much power so I wasn't interested in those graphs, but at the same time those graphs don't really correspond to other declared parameters.
10Ω resistance in series with the output when using loads of 30-60 Ω is not so big problem.
I listened to this amplifier isodynamic headphones that had a lower sensitivity and very low impedance (16Ω) for headphones, but the acoustic power was sufficient and I use +/-12V not +/-15V which is the maximum recommended for the IC.
The new TI headphone and op-amp offerings do seem pretty appealing, but I'm bummed they are all surface mount packages.
Call me old school, I'll stay in the domain of through-hole packages. I've gotten really good at clean, dense perf-board construction, and have rarely found it wanting.
I'm impressed with the Omicron, very well designed, well thought out. I really don't have a golden ear (I'm 54) to hear the differences so I have been perfectly happy with the Rod Elliott ESP design project 113- Incredibly simple, easy to build, plenty of power, sounds excellent, overall a great return for the investment. It drives my 32 Ohm Philips SHP-9500 effortlessly, as well as bookshelf speakers for near-field.
Call me old school, I'll stay in the domain of through-hole packages. I've gotten really good at clean, dense perf-board construction, and have rarely found it wanting.
I'm impressed with the Omicron, very well designed, well thought out. I really don't have a golden ear (I'm 54) to hear the differences so I have been perfectly happy with the Rod Elliott ESP design project 113- Incredibly simple, easy to build, plenty of power, sounds excellent, overall a great return for the investment. It drives my 32 Ohm Philips SHP-9500 effortlessly, as well as bookshelf speakers for near-field.
I tried the OPA1622 as a headamp, with 32ohm headphones. It's nowhere near as good as the Whammy headamp. And it wouldn't even suit these demanding headphones. A Whammy with maximum supply voltage and some stronger output transistors (IRF510/9510 or IRF610/9610) I think would give a satisfactory result. It is only necessary to take into account the permissible voltage of the OPA. That's why I chose the minimum voltage (+-15V) to be able to use any OPA. Specifically, MUSES 02 is built in, its max. supply voltage is +-16V.
The Whammy is Class A with a transition to Class AB, like any PP amp. When the transition will happen, it depends on the quiescent current and the impedance of the headphones. I chose 60mA, but it can be significantly less. I think 17mA is the minimum so that there are no transition distortions. I don't know where the clipping is with the +-15V supply, I didn't measure it. Let's say it is at 22V P-P, that corresponds to 1.2W RMS at 50ohm. For 2W RMS at 50ohm (28V P-P) it should have say +-18V power supply. We just have to watch out for the OPA PS limit. It could be reworked so that the OPA has a 3-4V lower supply voltage than the output stage. But there are already finished PCBs on diyaudio. There is a Full Kit as well.
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LM1875 is the best bet so far.
With a supply +/-18V to +/-20V and a gain like 10 it will give 2W into 50 Ohm.
I agree with EUVL.
I had an idea to make a headamp with TDA7296, I even got ICs and PCBs. Right now I'm not sure that would be all that good.
But chipamps are boring.
https://www.diyaudio.com/community/threads/the-xen-xelf-headphone-buffer.338371/
Reviews see posts #2,12,13.
Patrick