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Estimating Amp Consumption on Op Amp Upgrade Dynamics Processors (HW)
Old 14th September 2018
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Brian M. Boykin's Avatar
Estimating Amp Consumption on Op Amp Upgrade

I’m trying to ballpark how many amps a new power supply needs to be for my console after all the new opamps are in. So for an OPA2134 I see 35mA for output current and a 5mA max for idle consumption. Is it 35mA per amplifier so 70mA for each chip since they’re duals? Is it practical think I’ll ever be driving every opamps to its max at the same time? My guess is there’s a percentage or rule of thumb once you figure potential max consumption?


Old 14th September 2018
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jaddie's Avatar

Output current depends on the load the amp is driving. You haven't stated that.
Old 14th September 2018
Gear Addict

I assume you're replacing existing opamps with a different (presumably improved performance) opamps.

Look up the idle power consumption for the originals, and for your replacements. The load on the output will be unchanged with the new opamps (or, at least, close enough to unchanged for this sort of computation), so pretty much the only thing that would be changing is the idle power.

My guess is that there won't be enough of a change to need to worry about upgrading the power supply, assuming it's appropriately specified to begin with. If they started out with a marginally adequate power supply, then it may be worthwhile to do some work there...but it probably would be without the opamp upgrade, as well.

(To answer your question, the max power output/current output would typically be per amplifier, and so twice that for the dual package. Sometimes there's also a maximum specified for the package as a whole, usually lower than the sum of the individual ones, which means you shouldn't drive both amplifiers to full power simultaneously. Most opamp circuits do not come near using the maximum drive of the opamps in practice, though of course that's a gross generalization. As jaddie wrote, the output power depends on the load being driven, and the signal it's being driven with. Usually the load is not large in signal processing circuits, just the input of the next stage in the signal chain.)
Old 14th September 2018
Put a current meter on the power feeds and measure it?
Old 14th September 2018
Lives for gear
Brian M. Boykin's Avatar
Thank you, thank you and thank you. You’ve pointed me in the right direction. I have some Power One HE15 9amp modules here I bought years ago along with a 48v phantom power module. Life got in the way and I’m having to relearn lost knowledge. I’m trying to decide if I want to risk frying my console or have one built. Either way I’d like to get close so I don’t over build or over buy. I have 2 Soundcraft 400b’s. A 16/4/2 and a 24/4/2. The 24 is half done and the 16 untouched. I’m not doing anymore to the 24 till I figure this out.

Jim, I picked up an Aphex 651. When it gets here I’m sending off it and 2 input modules. I was looking at my master module from the 24 you did and the only thing you did that I haven’t figured out how to duplicate is soldering to traces. I have some scrap PCB’s I’m gonna practice on.

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