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Chip Amps Amplifiers based on integrated circuits

By-passed input amp. Is this OK?
By-passed input amp. Is this OK?
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Old 21st December 2006, 09:45 PM   #1
nelsonvandal is offline nelsonvandal  Sweden
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Default By-passed input amp. Is this OK?

I have a Xenos OHA-REP headphone amp. Originally there was an OPA2134 as input amp and two LMH6543 as output stage (now LMH6654). The sound was a bit dull and congested. I've rolled some input op-amps: LM4562 - too artificial and unfocused but sparkling and fun, AD8620 - too harsh treble and thin but great control and soundstage, AD746 - too soft and a bit boring and high noise level but very neutral balance and soundstage. Now I'm awaiting AD823 and 8058.

I got bored with AD746 and removed it. I soldered input cables directly to pins 1 and 7 (used for output from the op-amp). Still using the output stage. No more noise, no more dull sound, no DC-offset. Now it's fun again. Neutral tonal balance (maybe a bit bright), great dynamics, fun. Can you really do this? Do I need an input op-amp? What can go wrong? Is there any op-amps that doesn't colour the sound to use with 9 V battery supply?
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Old 4th January 2007, 11:49 PM   #2
odysseybmx414 is offline odysseybmx414  United States
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Location: Watertown, NY
hey if its workin with no offset and the chips arent heating up why wouldnt you be fine? also i like the opa134 not sure about the psu voltage for this chip tho
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