humm in sds headphone amp.

rwagter · 18th August 2002, 08:12 PM

I just finished my first small ampproject, a SDS headphone amp but I got a problem: HUMMMMMMM. It's not very loud but is's there and when I approache the signal leads it get worse, I dont have to touch them to make it louder.
Since this is my first project and my understanding of EE and grounding is limited I'd appreciate some sugestions.

Ralph

jwb · 18th August 2002, 08:25 PM

I built that amp two years ago. It isn't the greatest amp ever, but I didn't have any trouble with hum. With the headphones removed, is there a DC potential across the outputs? Check that first.

Does it actually produce music?

Is the circuit ground connected to earth? What about the chassis?

rwagter · 19th August 2002, 06:46 AM

It does produce music and with dance you can't hear the humm but with classical music it's all over the place.

Yes I got 2.08 mV of DC accross the output connector (what can I do about it.

The total amp is connected to earth with a starground.

Ralph

rwagter · 19th August 2002, 07:25 AM

Oops,

just rememver that I disconnected the POT on the input. With the POT in place I don't measure any DC.

When I disconnect the ground of the output the humm get really soft but the sound is breaking up (echo's)?!

Any suggestions???

Ralph

jwb · 19th August 2002, 04:13 PM

It is hard to diagnose something like this, without actually seeing the amp. My next best guess is a bad solder joint, possibly somewhere in your ground. Check continuity of the circuit ground, chassis, earth, headphone jack, etc.

18th August 2002, 08:12 PM	#1
rwagter diyAudio Member Join Date: Jul 2002 Location: Netherlands	humm in sds headphone amp. I just finished my first small ampproject, a SDS headphone amp but I got a problem: HUMMMMMMM. It's not very loud but is's there and when I approache the signal leads it get worse, I dont have to touch them to make it louder. Since this is my first project and my understanding of EE and grounding is limited I'd appreciate some sugestions. Ralph

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
What's causing that #$%&@$ humm??	sachi	Chip Amps	10	9th February 2006 01:29 PM
Humm in my preamp...	Bryan	Tubes / Valves	5	19th November 2005 01:08 PM
System humm	Flemming J P	Everything Else	3	2nd December 2003 07:52 PM
Humm...first post :)	Sch3mat1c	Car Audio	3	26th February 2003 09:10 AM
Humm	whatgive	Tubes / Valves	4	8th February 2003 04:24 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

18th August 2002, 08:25 PM	#2
jwb diyAudio Member Join Date: Mar 2002 Location: San Francisco, USA	I built that amp two years ago. It isn't the greatest amp ever, but I didn't have any trouble with hum. With the headphones removed, is there a DC potential across the outputs? Check that first. Does it actually produce music? Is the circuit ground connected to earth? What about the chassis?

19th August 2002, 06:46 AM	#3
rwagter diyAudio Member Join Date: Jul 2002 Location: Netherlands	It does produce music and with dance you can't hear the humm but with classical music it's all over the place. Yes I got 2.08 mV of DC accross the output connector (what can I do about it. The total amp is connected to earth with a starground. Ralph

19th August 2002, 07:25 AM	#4
rwagter diyAudio Member Join Date: Jul 2002 Location: Netherlands	Oops, just rememver that I disconnected the POT on the input. With the POT in place I don't measure any DC. When I disconnect the ground of the output the humm get really soft but the sound is breaking up (echo's)?! Any suggestions??? Ralph

19th August 2002, 04:13 PM	#5
jwb diyAudio Member Join Date: Mar 2002 Location: San Francisco, USA	It is hard to diagnose something like this, without actually seeing the amp. My next best guess is a bad solder joint, possibly somewhere in your ground. Check continuity of the circuit ground, chassis, earth, headphone jack, etc.