CKKIII Help

andrelim · 15th December 2010, 10:35 AM

I just built a CKKIII headphone amp, however I am experiencing various problems.
1. No sound output on the right channel.
2. Extremely distorted sound on the left channel.

The power part of my circuit seems to be working, the 15V and -15V test points measure 15.1V and -14.9V.

I am unable to get a consistent quiescent voltage on R23 and R47. It will jump from 0mV to 17-130mV.

I have the output transistors and they have heatsinks attached. I got some sound in the left channel after replacing them.

However almost no other voltage measures correctly.

Any help is greatly appreciated.

moschfet · 15th December 2010, 04:34 PM

Hi andrelim,

nice circuit

I estimate, that the hfe of Q9 (BC550C) is to high. Try a BD139, it is not react so sensitive.
And you maybe can increase R23/24 to 1 ohm.

andrelim · 16th December 2010, 01:33 AM

Could it be that I installed the wrong values for R2, R7 and R11?

andrelim · 16th December 2010, 02:20 AM

I have checked R2, R7 and R11 and they are the correct values.

andrelim · 16th December 2010, 04:55 AM

I have gotten both channels to work, but the sound is extremely distorted and intermittent. It cackles, pops and hisses. The severity changes with time, sometimes getting good other times it gets totally unintelligible.

AndrewT · 16th December 2010, 11:22 AM

are the green voltage values actual measurements of your circuit?

A working BJT should have ~600mVbe.
I can see many transistors that are turned off.
Now that you have some operation, can you repost voltage values, particularly Vbe of BJTs.

Inconsistent operation could be a sign of intermittent oscillation.

andrelim · 16th December 2010, 11:30 AM

The green voltages are actual measurements.
I will remeasure them later, but are the transistors supposed to stay cold?

15th December 2010, 10:35 AM	#1
andrelim diyAudio Member Join Date: Dec 2010	CKKIII Help I just built a CKKIII headphone amp, however I am experiencing various problems. 1. No sound output on the right channel. 2. Extremely distorted sound on the left channel. The power part of my circuit seems to be working, the 15V and -15V test points measure 15.1V and -14.9V. I am unable to get a consistent quiescent voltage on R23 and R47. It will jump from 0mV to 17-130mV. I have the output transistors and they have heatsinks attached. I got some sound in the left channel after replacing them. However almost no other voltage measures correctly. Any help is greatly appreciated.

16th December 2010, 11:22 AM	#6
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	are the green voltage values actual measurements of your circuit? A working BJT should have ~600mVbe. I can see many transistors that are turned off. Now that you have some operation, can you repost voltage values, particularly Vbe of BJTs. Inconsistent operation could be a sign of intermittent oscillation. __________________ regards Andrew T.

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15th December 2010, 04:34 PM	#2
moschfet diyAudio Member Join Date: Jul 2008 Location: Hannover	Hi andrelim, nice circuit I estimate, that the hfe of Q9 (BC550C) is to high. Try a BD139, it is not react so sensitive. And you maybe can increase R23/24 to 1 ohm.

16th December 2010, 01:33 AM	#3
andrelim diyAudio Member Join Date: Dec 2010	Could it be that I installed the wrong values for R2, R7 and R11?

16th December 2010, 02:20 AM	#4
andrelim diyAudio Member Join Date: Dec 2010	I have checked R2, R7 and R11 and they are the correct values.

16th December 2010, 04:55 AM	#5
andrelim diyAudio Member Join Date: Dec 2010	I have gotten both channels to work, but the sound is extremely distorted and intermittent. It cackles, pops and hisses. The severity changes with time, sometimes getting good other times it gets totally unintelligible.

16th December 2010, 11:30 AM	#7
andrelim diyAudio Member Join Date: Dec 2010	The green voltages are actual measurements. I will remeasure them later, but are the transistors supposed to stay cold?

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