[sdiy] 10 x amp for line to modular level

David Huss dh at atoav.com
Fri Mar 1 08:41:17 CET 2024


What do you mean with line Level? Pro Audio +4dBu or whatever comes out of a consumer device like the headphone output of a laptop?

If it is pro audio line that is roughly 3.4 V peak-to-peak so a gain of 10 would result in a voltage swing of 34 V peak-to-peak. That in turn means your opamps need to be operated with a voltage of at least 34 V or ±17V, if you use rail-to-rail opamps or more if you use non-rail-to-rail types — if you use lower supply voltages you still may get a Gain of 10 on small signals, but loud signals will clip (opamps cannot output signals swinging beyond their supply voltage). Note that non-rail-to-rail opamps will clip earlier!

Opamps like the OPA2134 have a max supply voltage of 36V, so that would fit the bill.

As of the supply voltage: ±18V or 36V single supply is not that common. Maybe it makes sense to go for a more common ±15V and you convert your wall warts voltage to bipolar using a DC/DC converter like the Meanwell DCWN03A-15 (see <https://www.meanwell-web.com/en-gb/dc-dc-regulated-dual-output-converter-input-9-dcwn03a--15>) — this has a unipolar input of 9 to 18 V and creates two outputs (+15V and -15V).

This way you get 30Vpp max which might already be enough?

Cheers,
atoav

On March 1, 2024 2:04:20 AM UTC, JoeF <frey at radioles.com> wrote:
>Hello, I've assembled a couple of video synths that can be audio reactive but they need a bigger signal than line level to work well. I want to build a 10x gain stage. Will any op-amp work if I am using a wall wart that is dc? Any tips would be helpful. TIA. JoeF.
>
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