| Nabetse |
I just built a USB DAC based on the PCM2902 + TPA6120A2 for driving my 32 ohm headphones, between the output of the pcm2902 and the input of the TPA6120 I put a OPA2134 with a gain of 3, the sound is great, but here is my question: I hear the same (volume and quality) at the output of the TPA6120 and at the output of the OPA2134, so the OPA2134 is working like a Cmoy headphone amp, and now I don't what's the difference between the Cmoy and the TPA6120A2????? :confused: :confused:
attached are the eagle files of the DAC+AMP, I now the pcb is awful, but it works! |
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| jcx |
if you really want to report the huge differences between amps you see here and on diyaudio you really shouldn't have 2 amps side by side where you can compare them quickly and at the same volume - you need some time to forget the fine details of the sound and some work with the soldering iron to contemplate and build your expectation of the mod's effect
the 2134 shouldn't be too bad up to ~15 mW into 32 Ohm headphones, +12 dB pwr added to high 98 db/mW headphone sensitivity (most grado's) gives 110 dB spl before clipping/distortion - that's loud
the 6120 is probably limited by voltage swing w +/- 5 V supplies to ~ 3 V peak amplitude vs the ~1 V peak the 2134 can manage before current limiting - so the 6120 can manage ~ 10x the peak pwr vs the 2134 or 120 dB spl - that's really loud
since 110 dB spl is unsafe listening level for any length of time the difference should only show on very high dynamic range recordings of high dynamic instruments - no cd that is ever played on the radio will qualify |
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| peranders |
| quote: | Originally posted by Nabetse
....and now I don't what's the difference between the Cmoy and the TPA6120A2????? :confused: :confused: |
Some people claim really huge differences between opamps but rather few can admit that the difference is really small. I admit that the difference is rather small if good opamps are used. I have made a couple of headphopne amps now and all sound pretty much alike but they appeal to me differently. Right now I like the TPA6120 based amp the best but soon I have made myself a current feedback amp with all discrete surface mounted parts and on top of this a super regulated power supply. |
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| peranders |
| quote: | Originally posted by jcx
the 6120 is probably limited by voltage swing w +/- 5 V supplies to ~ 3 V |
Not true, I'm afraid. The TPA6120 can take max +- 16.5 volts. |
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| jcx |
| nabetse' cirucit diagram shows +/-5 V supplies |
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