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Old 12th February 2017, 05:42 PM
Richard Richard is offline
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Join Date: Dec 2005
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Default Re: WAD K5881 Circuit Diagram Needed

Originally Posted by yuming916 View Post
Sure, Ill take care of it.
BTW, there is a footnote saying that C1 be soldered to the input phono socket.
Then how about an input aux socket? Is it the same connection?
That type of socket is often called a "Phono" socket or "RCA" socket even if the input is flat and at line level and not for Phono.

In this case there is just one input socket per channel on K5881PSE and it is for a flat frequency signal at 280mV for full output.

Full specs are 17W/channel output, 30Hz - 25KHz, 0.16% distortion, 60dB separation, -90dB noise, 1.5mV hum, and 280mV sensitivity.

C1 is optional. It is there as a DC blocker in case an input signal has DC on it. This is not common these days as the norm now is for DC blocking to be in the source component. Its second use is to make a filter with R1 100K gridleak to roll off low frequencies from 16Hz to prevent TX saturation. These might have come from vinyl warp/rumble in the past but most folk don't find a problem with digital and modern TTs so it's up to you.

The note about C1 being soldered to the "input phono socket" just means that's where it can be easily located inline (see schematic) if you decide to fit it.

So just 280mV line input is needed and, with high 100K input impedance, a passive control using a 50K pot and selector switch near the amp would be fine. Otherwise any regular preamp of course or even CD/streamer direct if the player has its own vol control.
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Old 18th February 2017, 10:07 AM
yuming916 yuming916 is offline
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Location: changsha, hunan, china
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Default Re: WAD K5881 Circuit Diagram Needed

Hi Richard,
Thanks for your reply. I got it.
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Old 14th March 2017, 01:48 PM
yuming916 yuming916 is offline
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Join Date: Feb 2017
Location: changsha, hunan, china
Posts: 13
Default Re: WAD K5881 Circuit Diagram Needed

Hi all,
Thanks for all your help on providing various kinds of informations. After weeks of work, I have finally collected all the components needed and solder them all together according to the prescriptions. It sounds great at this stage but I am sure it can be made even better.
But now I am not clear about the following questions, any one is welcome to provide an answer.
1) what is the total power consumption for the WAD K5881 PSE power AMP?
Mine is measured to be 220V X 1.4A AC.
2) should the chasis itself be grounded? and where is the proper ground point?
3) I can feel warmth by touching on the transformers, but the output transformers feel even warmer than the power transformer, is it normal?

Last edited by yuming916; 14th March 2017 at 01:59 PM.
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