I will have a look at the scematics, and see where they are at.
I dont know if i dare risk the consequense of DC voltage to the speakers. How much difference will there be (besides the cost) between changing the capasitors with better ones, and bypassing them?
I cant help thinking about Murphys Law, when you mention the risk of speaker dammage. The Peerles units i have used in my speakers are discontiued, and i would hate the thought of giving them up. They are made from a series of HES speakers they made in the 90´s, and have that distinkt dynamik and controlled sound that are very dear to me. I have upgraded them through time with better cappasitors, coils, wirring, and coating of the woofer, so loosing them is realy not an option to me.
I dont know if i dare risk the consequense of DC voltage to the speakers. How much difference will there be (besides the cost) between changing the capasitors with better ones, and bypassing them?
I cant help thinking about Murphys Law, when you mention the risk of speaker dammage. The Peerles units i have used in my speakers are discontiued, and i would hate the thought of giving them up. They are made from a series of HES speakers they made in the 90´s, and have that distinkt dynamik and controlled sound that are very dear to me. I have upgraded them through time with better cappasitors, coils, wirring, and coating of the woofer, so loosing them is realy not an option to me.
You can use a DC speaker protection circuit. I advise this: Velleman nv
It kicks in when DC on speaker outputs exceeds 1 Volt. I use 3 pieces of it in a 6 channel amplifier and it works flawless and reliable.
I'll check your sketch later this weekend.
It kicks in when DC on speaker outputs exceeds 1 Volt. I use 3 pieces of it in a 6 channel amplifier and it works flawless and reliable.
I'll check your sketch later this weekend.
I have encountered a problem, that started this friday. There are some klipping in the high notes now, just like when the amplifier is driven to hard, but it is there at all levels. I started with changing the butterfly´s in my tweeters, with the same result. It is also there when i am listening to music over my headphones.
What can course this?
What can course this?
I don't understand how a signal could be driven into clipping at only the high notes ...
Seems there is some oscillation in your amp. Take out the Obligattos; the very long leads have quite some inductance in series with the actual capacitor and can form an oscillator.
Seems there is some oscillation in your amp. Take out the Obligattos; the very long leads have quite some inductance in series with the actual capacitor and can form an oscillator.
Today i found some time to change the possition of the decoupling caps, and switch them to some film cappasitors.
It has done the job, there are no oscilations, and the bas seems a bit deeper and not so round as it was with the Obligato´s.
I have given it some thought, and i has opted for changing the electrolytes in the signal path to Elna Silmic II´s, instead of bypassing them. I hope that i can find some time to do that in some couple of weeks.
Cheers
It has done the job, there are no oscilations, and the bas seems a bit deeper and not so round as it was with the Obligato´s.
I have given it some thought, and i has opted for changing the electrolytes in the signal path to Elna Silmic II´s, instead of bypassing them. I hope that i can find some time to do that in some couple of weeks.
Cheers
Probelms with PMA-925R
Hi guys,
I have a pma-925r amplifier that has been my loyal friend for many years.
Lately it has started to cut the sound output when turning up volume a little more then medium.
Suspecting problems with capacitors, could this be the case.
Do you think I could change them and it would fix the problem?
Low and Medium level volume works fine; but going up output is cut.
Reducing base makes possible to go higher but at a moment it cuts again.
There is kind of a tick from the amplifier when it happens. About 2 seconds after reducing the volume there is a click and it comes on again..
Can anybody please help me;
Hi guys,
I have a pma-925r amplifier that has been my loyal friend for many years.
Lately it has started to cut the sound output when turning up volume a little more then medium.
Suspecting problems with capacitors, could this be the case.
Do you think I could change them and it would fix the problem?
Low and Medium level volume works fine; but going up output is cut.
Reducing base makes possible to go higher but at a moment it cuts again.
There is kind of a tick from the amplifier when it happens. About 2 seconds after reducing the volume there is a click and it comes on again..
Can anybody please help me;
That click sounds like the protection relay cutting in. Don't overlook other things. Try connecting just one speaker at a time, there could be a speaker or speaker wiring issue.
If it is the amp then its hard to diagnose at a distance. The only real correlation between higher volume and it cutting out is that the protection circuitry might be sensing the load current. Also you check the DC offset of the amp and see if anything goes amiss there when playing music. Anything over say 30 millivolts with no signal could indicate an issue. When playing music a meter doesn't really show things accurately but it would show a large offset.
If it is the amp then its hard to diagnose at a distance. The only real correlation between higher volume and it cutting out is that the protection circuitry might be sensing the load current. Also you check the DC offset of the amp and see if anything goes amiss there when playing music. Anything over say 30 millivolts with no signal could indicate an issue. When playing music a meter doesn't really show things accurately but it would show a large offset.
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