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Cause from Speaker pulsating ?

psychoaudio

psychoaudio

I didn't do it
Subscriber
Very strange. Only on left channel. Any ideas? MC225/MX110Z combo Streaming via chromecast audio in aux.

update: switched MC225 to Dynaco ST 35 and it’s all good. What could be the issue with the 225? (It’s been gone through)

Happy New Year to all !
 
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Sounds like low frequency oscillation.
From the Tube amp debugging page: 'Motorboating' is almost always a signal that the decoupling capacitors in the B+ lines of the preamp section are going high impedance, not decoupling properly. Replace the B+ decoupling capacitors at least for the preamp. Since the other capacitors are old, also, consider replacing ALL of the electrolytic capacitors in the amp
 
quartersaw said:
Sounds like low frequency oscillation.
From the Tube amp debugging page: 'Motorboating' is almost always a signal that the decoupling capacitors in the B+ lines of the preamp section are going high impedance, not decoupling properly. Replace the B+ decoupling capacitors at least for the preamp. Since the other capacitors are old, also, consider replacing ALL of the electrolytic capacitors in the amp
Click to expand...

hmm. Is there might be another reason perhaps ? Both units have been thoroughly gone through .
 
psychoaudio said:
hmm. Is there might be another reason perhaps ? Both units have been thoroughly gone through .
Click to expand...
Always possible that something has gone out of spec, since the unit was last inspected. You might want to have the tech who did the work, explain what was replaced. There wouldn't be a need to replace components that still met spec, at that time.
 
I have that problem in my system if my anti skate is not right, my subsonic filter is off, and or my volume is really high - and only on an LP. It’s feedback into my high output 5MC needle I believe. Sometimes could be the LP itself and just high volume with the subsonic filter off.


Woofers poking their head out at 10 hertz like heyooo what’s going on out here. :eek:


**Left channel only on yours leads me to believe your anti skate is off and it’s possible you don’t have a subsonic filter.

but then you go and say it’s digital. Sorry for the rambling :biggrin:
 
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