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Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

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Old 13th December 2011, 10:35 AM   #1
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Default Loudness stage

Hi all.
I'd like to build a simple "loudness" stage for include beetwen TV low level output and the line input in my amplifier.
I'm thinking in a operational step like LM387 or so. But I have not idea about RC filters.
I need to have a single +V for the circuit (if is +5V, better).
Thanks for your help
WebWilly
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Old 14th December 2011, 07:34 AM   #2
Mooly is offline Mooly  United Kingdom
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"Loudness" stage often means a modified frequency response such as the old "loudness" control that was always fitted to 1970/80's music centres and amplifiers.

Or do you mean a preamplifier ? to just boost the signal level.
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Old 14th December 2011, 07:54 AM   #3
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Thanks Mooly.
I mean the old "loudness" control you refered. The aim is to listen the TV in very low sound level in the room but with confortable feeling. I know that this is not purity sound, because some tones will be modify.
Thanks
WebWilly
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Old 14th December 2011, 01:01 PM   #4
Mooly is offline Mooly  United Kingdom
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Haven't anything I can think of to recommend tbh. A proper loudness control uses a tapped volume control.

This was an odd design with limitations but might achieve what you are after at a fixed level,
VOLUME CONTROL PASIVE !
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Old 15th December 2011, 12:56 AM   #5
PRR is offline PRR  United States
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> in very low sound level in the room but with comfortable feeling.

Click the image to open in full size.
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Old 15th December 2011, 06:50 AM   #6
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Many tanks Mooly and PRR. I'll try with this and let you know the result.

PRR: tha capacitor is 0.03 uF if I read correctely, isn't ?

Thanks
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Old 15th December 2011, 06:06 PM   #7
mjf is offline mjf  Austria
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..........examples from an old hifi - book
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Old 5th March 2012, 11:44 AM   #8
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Default Real time Loudness Meter

check out this URL:
Grimm Audio

The Luxman Receiver R5030 uses a variable loudness filter - go to page 15 about sm from
Luxman R-5030 | Owners Manual, Service Manual, Schematics, Free Download | HiFi Engine
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Old 28th July 2012, 04:25 AM   #9
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Hi guys!
You can offer a schematic or project for the active filter for loudness control.
thank you!
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Old 7th August 2012, 05:47 PM   #10
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This is a passive loudness circuit that can be put on the end of a pre amp...

Click the image to open in full size.

The effect as you turn the pot over full rotation is...

Click the image to open in full size.

The 33k resistor is just to simulate a typical load and is not needed it will drive a following circuit over about a 20-100k range withought very much change in the frequency response.

The component values can be scaled to for instance use the 10k motorised pot widely available here in Oz. In this case just double all resistors and halve capacitors.
rcw
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