Crackling at high volume

matheprat · 20th January 2007, 08:42 PM

I've built one channel of a Gainclone (LM3886). At medium-high volume, the sound starts to crackle at a definate point, below which is fine. I tried putting a zobel network (100 nf and 10 ohms) across the output and it seemed to reduce the noise, but it can still be heard.
What else can be done to help?
Many thanks.

peranders · 20th January 2007, 08:49 PM

How about cooling? Maybe it's the protection circuits that you trigger?

Original Burnedfingers · 21st January 2007, 02:32 AM

Gain clowns sound very bad when they clip. It is very possible that you are clipping the amp.

AndrewT · 21st January 2007, 08:10 AM

Hi,
give us some constuction/compatability details.

Transformer VA & Vac
Dual or single bridge
Smoothing uF
Inverting or non-inverting
Speaker impedance & sensitivity

Nordic · 21st January 2007, 08:20 AM

How big is your heatsink?

AndrewT · 21st January 2007, 10:10 AM

Hi Mat,
have you fitted a heatsink, or have you gone quiet while you are fitting one now?

Let's hear from you.

Nordic · 21st January 2007, 10:27 AM

I think we killed another one, Andrew.

matheprat · 21st January 2007, 10:41 AM

Sorry, been asleap.
Yeah, I have a large heatsink fitted to the chip. 4 x 2 inches. It gets slightly warm to the touch, so I don't think the chip is overheating.
The transformer is 160 va, and the power rails are +- ~38v. The caps are 5600 uf, and the amp is non-inverting. The speaker inpeedence is 8 ohms.
Many thanks.

Original Burnedfingers · 21st January 2007, 10:56 AM

What is the speaker efficiency? Your speakers how many db with
1 watt@ 1 meter?

matheprat · 21st January 2007, 11:07 AM

I don't know. How can I find that out? It's not on the speaker anywhere.
Many thanks.

20th January 2007, 08:42 PM	#1
matheprat diyAudio Member Join Date: Jan 2007	Crackling at high volume I've built one channel of a Gainclone (LM3886). At medium-high volume, the sound starts to crackle at a definate point, below which is fine. I tried putting a zobel network (100 nf and 10 ohms) across the output and it seemed to reduce the noise, but it can still be heard. What else can be done to help? Many thanks.

20th January 2007, 08:49 PM	#2
peranders Electrons are yellow and more is better! diyAudio Member Join Date: Apr 2002 Location: Göteborg, Sweden Blog Entries: 4	How about cooling? Maybe it's the protection circuits that you trigger? __________________ /Per-Anders (my first name) or P-A as my friends call me

21st January 2007, 08:10 AM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, give us some constuction/compatability details. Transformer VA & Vac Dual or single bridge Smoothing uF Inverting or non-inverting Speaker impedance & sensitivity __________________ regards Andrew T.

21st January 2007, 10:10 AM	#6
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi Mat, have you fitted a heatsink, or have you gone quiet while you are fitting one now? Let's hear from you. __________________ regards Andrew T.

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21st January 2007, 02:32 AM	#3
Original Burnedfingers diyAudio Member Join Date: Nov 2002	Gain clowns sound very bad when they clip. It is very possible that you are clipping the amp.

21st January 2007, 08:20 AM	#5
Nordic diyAudio Member Join Date: Sep 2005	How big is your heatsink?

21st January 2007, 10:27 AM	#7
Nordic diyAudio Member Join Date: Sep 2005	I think we killed another one, Andrew.

21st January 2007, 10:41 AM	#8
matheprat diyAudio Member Join Date: Jan 2007	Sorry, been asleap. Yeah, I have a large heatsink fitted to the chip. 4 x 2 inches. It gets slightly warm to the touch, so I don't think the chip is overheating. The transformer is 160 va, and the power rails are +- ~38v. The caps are 5600 uf, and the amp is non-inverting. The speaker inpeedence is 8 ohms. Many thanks.

21st January 2007, 10:56 AM	#9
Original Burnedfingers diyAudio Member Join Date: Nov 2002	What is the speaker efficiency? Your speakers how many db with 1 watt@ 1 meter?

21st January 2007, 11:07 AM	#10
matheprat diyAudio Member Join Date: Jan 2007	I don't know. How can I find that out? It's not on the speaker anywhere. Many thanks.

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