The Apheared 47 amplifier in an Altoids Tangerine Sours mint tin.
A47
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Hi Ben,
After looking around have decided to go with your design which seems better suited to my phones.
Would be grateful for your comments on these points.
The OPA datasheets recommend 10nf ceramic caps across the power rails, not on your diagram but worth adding ?
On your diagram it shows the OPA2227 , though your text says use the OPA2134, the input dc blocking cap C1 is 1uF, but noticed on other similar circuits with the 2134 ,like the CMoy, they use 0.1uF
Just wanted to check 1uF with an OPA2134 was correct ? not sure if 1.0 or 0.1 makes any difference ?
Also saw that the Mini3 design uses a ferrite beads on the outputs, is that something you have though worthwhile adding ?
many thanks
Will, UK
Hi Will,
The 2227 and 2134 are interchangeable. It might very well be worthwhile adding 10nf across the power rails. I never considered that. On the 1 vs 0.1, there’s really no difference. I believe I used 1 because it was in the original Apheared design. It’s been years since I did this project and I’m by no means an expert. Just wanted to let you know in case you were giving my design too much respect 🙂