External Volume Control.

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I have a question for a few audiophiles out there.

Could any of you point me to a good information source on audio device design?

The problem:

All the devices connected to my TV have different volume levels; My DvD player is very quiet, my Nintendo Wii is really loud and my digital cable box is about in between. I do not have a receiver and use the speakers built into my TV.

I would like to build a small device to equalize all the voltage levels. As an added bonus I'd like to build a headphone jack into the device.

From my limited knowledge of audio I have 2 ways to go, use a log pot to quiet down the sound on loud devices (but I have no clue what values to use) or amplify the quiet devices (again, I'd like to read up on audio amplifiers so that I know what to look for when I order them).

I'm not a cartoon character but I play one in real life.

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Usually these devices are on line-level, i.e. 0.7V rms for 0 dB (= loudest)
Impedances are in the 1k to 10k range.

The easiest (yet good) way to get all sources on the same level: use stereo-potmeters. 10 k will work fine.
Logarithmic is OK, but when it's hard to find those, linear will work fine too: it's all in the touch ;)
For the headphone-jack you will need to add a small amplifier. And yes, with a pot as well :) Using a wireless headphone makes things much easier: no need for that small amplifier, as the transmitters of wireless headphones use line-voltage levels.

The hardest thing IMO is to get it all in a decent housing.

Nard

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tessa and Tina, You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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Plons wrote:
Usually these devices are on line-level, i.e. 0.7V rms for 0 dB (= loudest)
Impedances are in the 1k to 10k range.
...
Nard

Thats the kind of stuff that confuses me. Like most industrial guys I understand the math behind impedance however, I've never used it for anything aside for phase balancing. The theory isn't hard I just haven't had to use it in any real world applications. Thats why this project has me excited :D

I'm not a cartoon character but I play one in real life.

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Yeah, c'est la vie.
If all manufacturers would stick to the standard, you wouldn't have to build such an "equalizer" as you plan to build now. But they don't ... sticking to standards.
In earlier days it was even worse: several voltage-levels @ several impedances, like 100 mV over 1 kohm, or 500 mV @ 200 kohm for recording inputs. Now THAT was confusing :)

Nard

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tessa and Tina, You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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All that matched impedance stuff was a hold over from the early days of telephony where everything was 600 ohms in and out.. there werent any big amps and matching the impedance gave 'maximium power transfer'... send as much of tht 0dB 1mW signal down the wire as possible. Impedance match also mattered when dealing with lines miles long. Today, an output comes from an opamp with a low impedance... it will put out +-10V peak into any load it can handle.. 1000K, 100K, 10K maybe even 1K if its a beefy opamp. The load 'bridges' the source. It presents a 'bridging impedance'. No power is transferred, but thats not important. Just keeping the voltage levels strong (out of the noise) and clean is whats important.

Imagecraft compiler user

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Quote:
c'est la vie.
I bet that's not how you say it in Dutch :)

Have you tried the setup for your TV? Some amplifiers have input attenuators built in already.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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Zo is het leven, John :)

A GIF is worth a thousend words   They are called Rosa, Sylvia, Tessa and Tina, You can find them https://www.linuxmint.com/

Dragon broken ? http://aplomb.nl/TechStuff/Dragon/Dragon.html for how-to-fix tips

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js wrote:

Have you tried the setup for your TV? Some amplifiers have input attenuators built in already.

I wish, my TV is fairly old.

I'm not a cartoon character but I play one in real life.