lm3886 no mute option

rtill · 23rd August 2009, 08:48 PM

hello,
curious if I don't want the mute option with the lm3886, do I just connect pins 4 and 8 together to the V- rail?

nigelwright7557 · 23rd August 2009, 10:08 PM

Quote:

Originally Posted by rtill

hello,
curious if I don't want the mute option with the lm3886, do I just connect pins 4 and 8 together to the V- rail?

No, leave pin 8 disconnected from pin 4.

djoffe · 24th August 2009, 01:02 AM

Be careful...as I read the data sheet, to disable the mute, you must pull at least 0.5 mA from the mute pin. You probably don't won't to pull a whole lot more than 1 mA. There is a note and equation that describes the resistor value you should use.

nigelwright7557 · 24th August 2009, 12:17 PM

Quote:

Originally Posted by djoffe

Be careful...as I read the data sheet, to disable the mute, you must pull at least 0.5 mA from the mute pin. You probably don't won't to pull a whole lot more than 1 mA. There is a note and equation that describes the resistor value you should use.

The datasheet shows a cap across the MUTE input and a resistor to a switch.
You dont need the resistor or the switch for none mute mode if I read the data sheet correctly.

AndrewT · 24th August 2009, 12:38 PM

pin8 open circuit leaves the Mute function ON. This mutes signal from the output.

Pin8 needs current (~1mA) to turn Mute function OFF. This allows full signal from the output.

One can permanently connect a resistor from Pin8 to Vee but the amp will switch ON, on power up and may produce a start up noise as the circuits come alive.

nigelwright7557 · 24th August 2009, 01:08 PM

Quote:

Originally Posted by AndrewT

pin8 open circuit leaves the Mute function ON. This mutes signal from the output.

Pin8 needs current (~1mA) to turn Mute function OFF. This allows full signal from the output.

One can permanently connect a resistor from Pin8 to Vee but the amp will switch ON, on power up and may produce a start up noise as the circuits come alive.

You could add an RC network to hold off the amp on power up.

rtill · 24th August 2009, 01:17 PM

it is working great, I put a 10k resistor between 4 and 8, powers up fine. Thanks guys.

I am having an issue though. I am using this power amp coupled to a tube preamp. I can't turn my volume past 2. If I do the amp cuts out. I am assuming I am putting too much of a load on the power amp. Could I couple these together with maybe a 470k resistor to try and remedy the issue?

The preamp is http://www.freeinfosociety.com/elect...iew.php?id=507

peranders · 24th August 2009, 01:32 PM

You can decrease the gain of the LM3886.

AndrewT · 24th August 2009, 01:32 PM

Hi Rtill,
what is the gain of the pre-amp?
What is the gain of the power amp?
What is the attenuation of the pot at position 2?
What is the load on the power amp?
What is the supply voltage to the power amp?
You have to give us some information if you want us to be able to offer informed advice.

23rd August 2009, 08:48 PM	#1
rtill diyAudio Member Join Date: Sep 2006	lm3886 no mute option hello, curious if I don't want the mute option with the lm3886, do I just connect pins 4 and 8 together to the V- rail?

24th August 2009, 12:38 PM	#5
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	pin8 open circuit leaves the Mute function ON. This mutes signal from the output. Pin8 needs current (~1mA) to turn Mute function OFF. This allows full signal from the output. One can permanently connect a resistor from Pin8 to Vee but the amp will switch ON, on power up and may produce a start up noise as the circuits come alive. __________________ regards Andrew T.

24th August 2009, 01:32 PM	#8
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	You can decrease the gain of the LM3886. __________________ /Per-Anders (my first name) or P-A as my friends call me

24th August 2009, 01:32 PM	#9
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi Rtill, what is the gain of the pre-amp? What is the gain of the power amp? What is the attenuation of the pot at position 2? What is the load on the power amp? What is the supply voltage to the power amp? You have to give us some information if you want us to be able to offer informed advice. __________________ regards Andrew T.

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24th August 2009, 01:17 PM	#7
rtill diyAudio Member Join Date: Sep 2006	it is working great, I put a 10k resistor between 4 and 8, powers up fine. Thanks guys. I am having an issue though. I am using this power amp coupled to a tube preamp. I can't turn my volume past 2. If I do the amp cuts out. I am assuming I am putting too much of a load on the power amp. Could I couple these together with maybe a 470k resistor to try and remedy the issue? The preamp is http://www.freeinfosociety.com/elect...iew.php?id=507

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