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Old 26th June 2005, 01:04 PM   #1
freezz is offline freezz  Australia
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Default Reducing Audio Line Output?

Hi All,
I have a Stereo preamp mixer which has a Line Output and is feeding into a Power Amp.
Can I somehow reduce the Audio Line output amplitude on the mixer using some sort of a attenuator, or perhaps inline resistors?

I'm finding that I have to have the amp volume controls very very low and still finding that my mixer output volume is set to half.
What I would like is to use my mixer volume controls to the fullest and not have the sound so load, but to do this I have to turn the amp to about one notch. What could be wrong?
PLEASE HELP!
Any suggestions would be appreciated

Freezz
rflachs@netspace.net.au
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Old 26th June 2005, 01:12 PM   #2
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Default Re: Reducing Audio Line Output?

Quote:
Originally posted by freezz
Hi All,
I have a Stereo preamp mixer which has a Line Output and is feeding into a Power Amp.
Can I somehow reduce the Audio Line output amplitude on the mixer using some sort of a attenuator, or perhaps inline resistors?

I'm finding that I have to have the amp volume controls very very low and still finding that my mixer output volume is set to half.
What I would like is to use my mixer volume controls to the fullest and not have the sound so load, but to do this I have to turn the amp to about one notch. What could be wrong?
PLEASE HELP!
Any suggestions would be appreciated

Freezz
rflachs@netspace.net.au

Hi,

This is a bit unusual. Could it be that the preamp/mixer has both an unattenuated line output as well as a volume controlled line output or preamp output, that you are not using? Do you have a pic of the backside/plug field?

Edit: I think I misread your post. Forget my reply.
Jan Didden
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Old 26th June 2005, 05:17 PM   #3
moamps is offline moamps  Croatia
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Default Re: Reducing Audio Line Output?

Quote:
Originally posted by freezz
Can I somehow reduce the Audio Line output amplitude on the mixer using some sort of a attenuator, or perhaps inline resistors?
What could be wrong?
Hi,

If you connected the mixer to a professional PA amplifier, the levels would be OK. But, if you connect the mixer to a home amplifier then the overall sistem gain will be too high. The simplest method to reduce the gain is inserting an L-pad resistive network (for example 10k/1K inside a cinch connector).

Regards,
Milan
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Old 27th June 2005, 05:31 AM   #4
freezz is offline freezz  Australia
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Default Re: Re: Reducing Audio Line Output?

Hi Milan and thankyou for answering my thread.
Just letting you know it is connected to a Pro Amp, all used for entertainment (DJ Gear) and not a home amp.
I did look up the L-Pad as you've recommended, can I just put one resistor in series to each channel on the outputs? Will that effect the quality or anything else? The reason I'm asking because I would like to keep it plain and simple without inserting a sub PCB
Due to it being low signal I guess I would'nt need to use anything bigger than a quarter watt resistor? is this correct?
Once again many thanks

Freezz

Quote:
Originally posted by moamps


Hi,

If you connected the mixer to a professional PA amplifier, the levels would be OK. But, if you connect the mixer to a home amplifier then the overall sistem gain will be too high. The simplest method to reduce the gain is inserting an L-pad resistive network (for example 10k/1K inside a cinch connector).

Regards,
Milan
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Old 27th June 2005, 07:05 PM   #5
moamps is offline moamps  Croatia
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Default Re: Re: Re: Reducing Audio Line Output?

Quote:
Originally posted by freezz
I did look up the L-Pad as you've recommended, can I just put one resistor in series to each channel on the outputs?
Hi,
you need two resistors.
Look at the picture below (20dB pads).
All resistors are 1/4W.
Regards,
Milan
Attached Images
File Type: jpg lpads.jpg (22.2 KB, 171 views)
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Old 28th June 2005, 02:59 AM   #6
Enzo is offline Enzo  United States
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The power amp has no level controls of its own?
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Old 28th June 2005, 05:35 AM   #7
ctardi is offline ctardi  Canada
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If I were to want to do the same thing with a TRS Plug, would 2 resistors mid line work? I am having a bit of trouble understanding your diagram.
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Old 28th June 2005, 05:50 AM   #8
imix500 is offline imix500  United States
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If you want to use TRS, just wire it up as pin 2- tip, pin 3- ring, and pin 1- sleeve. It will work the same.
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Old 28th June 2005, 06:47 AM   #9
freezz is offline freezz  Australia
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Default Re: Re: Re: Re: Reducing Audio Line Output?

Hi Milan and thanks for the reply
This may sound stupid but why 2 resistors? Why not just have 1 resistor per output inline on the output connectors.

Many Thanks
Freezz


Quote:
Originally posted by moamps


Hi,
you need two resistors.
Look at the picture below (20dB pads).
All resistors are 1/4W.
Regards,
Milan
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Old 28th June 2005, 07:21 AM   #10
moamps is offline moamps  Croatia
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Default Re: Re: Re: Re: Re: Reducing Audio Line Output?

Quote:
Originally posted by freezz
This may sound stupid but why 2 resistors? Why not just have 1 resistor per output inline on the output connectors.
Hi,
Amplifiers usually have 47kohm input impedance. To get 20dB attenuation with this impedance, the series resistor shoud be around 470kohm. This is the high impedance Lpad which is prone to EMI's and may inject noise, linear amplitude and phase distortion into the system. (in a nutshell)

Regards,
Milan
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