LM1875 Trebles Modifications - diyAudio
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Old 14th January 2013, 12:10 AM   #1
Joseph1 is offline Joseph1  Sri Lanka
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Default LM1875 Trebles Modifications

I have built my own 2.1 subwoofer system using 3 LM1875.It is a locally available kit.Also I corrected some mistakes on it.

The design works nicely.The only problem is the two satellite amps trebles is not enough.

I uploaded the schematic by tracing the KIT.You can go through the red covered area.

What modifications to be done to gain more trebles.

Thanks
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File Type: jpg LM1875 Gainclone.JPG (63.2 KB, 94 views)
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Old 14th January 2013, 01:15 AM   #2
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remove R24 and C14

attach input to C15 .........
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Old 14th January 2013, 01:22 AM   #3
Joseph1 is offline Joseph1  Sri Lanka
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Hi thanks for the help.

I corrected the mistake.Here is the corrected one
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Old 14th January 2013, 10:41 AM   #4
Joseph1 is offline Joseph1  Sri Lanka
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Hi I removed the R24 and C14 & checked the system.The gain increased much.

I mean from the two satellites its coming too much sound comparing to sub amp,so when hearing I cannot hear much bass from the sub amp.

Is there any gain ratio between satellites & sub amp in 2.1 systems?

Here is my system gains

Satellite amp Left = 20
Satellite amp Right = 20

Sub preamp TL072 gain = 12
Sub Amp = 20

When listening to music I always put BASS level in subamp to half way mark in linear potentiometer.

Last edited by Joseph1; 14th January 2013 at 10:43 AM.
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Old 14th January 2013, 10:44 AM   #5
basi is offline basi  Croatia
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Hi!!!Reduce R26 to 24k.
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Old 14th January 2013, 11:01 AM   #6
Joseph1 is offline Joseph1  Sri Lanka
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Hi I increased the value of R27 to 3.3K so the new gain will be -11.8.

Now the two satellites have -11.8 each.Now I can hear balanced sound.

But still the sub amp has these gains.

Sub preamp TL072 gain = 12
Sub Amp = 20

Is it ok?
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