O2 added offboard 1/4" now "pops" when turned on...

No problems with just the mini plug, but now getting a loud "pop" when turning on the amp after adding offboard 1/4" jack.

Do I need to remove the mini jack to get this right? That would be a major pisser seeing as I had the panel drilled out to include both mini and 1/4". 

Currently testing with my HD448's and the pop is fairly loud, not deafening but uncomfortable. 

Any pro tips?

Quote:

Originally Posted by Fred_fred2004 

sounds like you've got some DC on the socket, I'd be checking the wiring before you damage your headphones

These are the test headphones. This socket has 4 pins, R,L,Gr, and another one. What is that last one supposed to be, another ground? I just wired them all up to corresponding holes on the board. Music sounds fine and R, L are correct, so that much is covered. 

edit: switched the two ground wires still pops, took one ground off, still pops, put both grounds on plug ground, still pops. Pop is the same, no change in pop volume regardless.

Great, removed the 1/4" jack, and wires, and it still pops...

What did I do to the amp to cause this? I can't believe something got zapped, it sounds fine, same as it has since I last added and removed components... It's just this pop that has shown up out of the blue.

Quote:

Originally Posted by WhDemon 

Well I just finished building mine 10 minutes ago. Slight tick on powering and Slight Pop on shutdown but if theres music playing, I cannot hear it.

On shut down I've always gotten a low thump, never a click on power up till now though. Hopefully someone with knowledge of the situation can help us poor souls out. It's really frustrating that somehow I've introduced a click/pop when previously there was none.

Is it a problem with the "transistors upstream of the output stage"?

I replaced the 2068 with a 2227 and that made the pop louder. lol, sounds good though, sounds freaking brilliant actually. 2068 is a POS. Strained and horrible, weak, burn it!

edit: 2227 sounds distorted on certain tracks, weird, it's like it amplifies the dynamics.

NJM4562, pop is the same as 2068, sounds better though, less strained, maybe my 2068 is busted?

I replaced the voltage comparator with another opamp and the pop/click went away.

All I know, is it worked..  

At least I can use it without fear while the replacement is on the way.

BTW, does this make sense to anyone or did something ridiculous just happen?

Quote:

Originally Posted by agdr 

Just curious - what op amp did you replace the NJM2903D with?  Sounds like something happened to the chip that threw the timing of the power management circuit off.

 

I tried it with a few, they were all quieter on power on, the 4562 was completely silent on power on, OPA 2134 has a very light click, but to me it sounds better, especially with HD448's, they practically sound high-end, blimey!  

Quote:

Originally Posted by agdr 

Interesting!  With the op amps the pullup resistor R4 probably wouldn't be required either as it is with the open collector comparators like the NJM2903.

 

Yeah, I read in a Wikipedia article on voltage comparators that a regular op amp could be "pushed into service" in this role and it would probably work for situations requiring lower accuracy. 

Quote:

Originally Posted by Willakan 

What exactly are we changing the comparator for anyway? It is a part of the power management circuit and plays no part in amplifying anything. Playing around with it is just asking for trouble IMHO.

Mine was bad or something and the source of the "pop" when turning on the amp with phones plugged in. Might be something else in the circuit, I can't be certain.