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Cheap as Chips OPA1688 Low-THD Muscle Amp
Cheap as Chips OPA1688 Low-THD Muscle Amp
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Old 13th September 2018, 05:06 AM   #201
xrk971 is offline xrk971  United States
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Cheap as Chips OPA1688 Low-THD Muscle Amp
Dual OPA1688 Parallel hand-etched amp now boxed up with DC-DC +/-18v dual rail power supply from SHPA project.

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Cheap as Chips OPA1688 Low-THD Muscle Amp-opa1688-2x-parallel-cased-01-jpg

Cheap as Chips OPA1688 Low-THD Muscle Amp-opa1688-2x-parallel-cased-02-jpg
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Last edited by xrk971; 13th September 2018 at 05:09 AM.
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Old 13th September 2018, 05:47 AM   #202
zman01 is online now zman01  Bangladesh
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Cheap as Chips OPA1688 Low-THD Muscle Amp
Cool! Nice work.

I would be tempted to say that one of these days you should do a hand-built chassis, but your time is better spent designing/ building amps and preamps.

Last edited by zman01; 13th September 2018 at 06:00 AM.
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Old 13th September 2018, 06:17 AM   #203
Dibya is offline Dibya
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Looks so neat ! I am jealous on your craftsmanship. I always create some mess.
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Old 13th September 2018, 12:00 PM   #204
xrk971 is offline xrk971  United States
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Cheap as Chips OPA1688 Low-THD Muscle Amp
Thanks, guys! Casework, even with pre-drilled/cut cases like this still take an enormous amount of time. I had to drill the hole for the headphone jack in the front as this was a Class D speaker amp case. Plus all the holes on the baseplate. Then a cover plate for the 5.5mm barrel jack to replace IEC jack. I can’t imagine how much more time for a custom case.

This amp is surprisingly good sounding - I am almost surprised how good it sounds. It is very quiet. No noise whatsoever (hiss or hum) even with volume all the way up when source is not on. Having +/-18v rails really gives the OPA1688 some headroom for great dynamics.

The big discrete DC coupled SE Class A amps next to it sounds better of course, more power and more dynamics. But when I get the 8x parallel OPA1622 built I am not going to be so sure this will still be true.

I am going to have to get back to work on the 1622 project and order the BOM (thank you to Zman01 for helping me with this).
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Last edited by xrk971; 13th September 2018 at 12:04 PM.
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