Please help...
I'm running my clone KSA 50 for 3 days now. I was very happy with sound but i found something strange, when i connect an input to the amp the right speaker will pull back while the left speaker is not. The same thing if i will short the input, this is only in the rigth channel. The left channel is okey. I measured the voltage in the speaker terminal and it is 0VDC.
Farley
I'm running my clone KSA 50 for 3 days now. I was very happy with sound but i found something strange, when i connect an input to the amp the right speaker will pull back while the left speaker is not. The same thing if i will short the input, this is only in the rigth channel. The left channel is okey. I measured the voltage in the speaker terminal and it is 0VDC.
Farley
Hi,
it seems like it might be a build up of DC bias due to leakage past the DC blocking capacitor.
It is advisable to ALWAYS wire in a high value (1M0 to 2M2) resistor from input/output terminal to short the DC to audio ground.
Although, Croft have discovered that their range of tube pre-amps sound better with this resistor removed (they used to fit it).
it seems like it might be a build up of DC bias due to leakage past the DC blocking capacitor.
It is advisable to ALWAYS wire in a high value (1M0 to 2M2) resistor from input/output terminal to short the DC to audio ground.
Although, Croft have discovered that their range of tube pre-amps sound better with this resistor removed (they used to fit it).
swap input cables
Hi,
Does the woofer stay 'in' or 'out', or does it return to the normal position after a second?
Swap the input cables from left to right. If the other channel does the woofer trick then there is DC on the input.
Did you fit input blocking caps? is it possible oneof them is bad?
HTH
Stuart
Hi,
Does the woofer stay 'in' or 'out', or does it return to the normal position after a second?
Swap the input cables from left to right. If the other channel does the woofer trick then there is DC on the input.
Did you fit input blocking caps? is it possible oneof them is bad?
HTH
Stuart
The woofer stay in.
Yes I swapped the input cables but the same channel of the amp has the problem.
This will happen also if I will short the input, the speaker will stay in. When I shorted the input in the other channel this will not happen.
I didn't fit an input blocking cap. I am using Pinkmouse board.
Farley
Yes I swapped the input cables but the same channel of the amp has the problem.
This will happen also if I will short the input, the speaker will stay in. When I shorted the input in the other channel this will not happen.
I didn't fit an input blocking cap. I am using Pinkmouse board.
Farley
Hi,
fit a shorting plug to your input and re-set the DC output offset.
Switch off and re-connect the interconnect.
Switch on and recheck the output offset.
The output offset, after following the initial setting up, measures the pre-amp offset when loaded with your normal system connections. The DC gain of the Klone is one. i.e. DCin = DCout.
You may need to check/repair your pre-amp output arrangement. Is it DC block or servo or none?
The shorting plug is a standard RCA plug with a wire link soldered between the pin and the shield. Make up a pair of these and keep for future setting up and/or testing.
fit a shorting plug to your input and re-set the DC output offset.
Switch off and re-connect the interconnect.
Switch on and recheck the output offset.
The output offset, after following the initial setting up, measures the pre-amp offset when loaded with your normal system connections. The DC gain of the Klone is one. i.e. DCin = DCout.
You may need to check/repair your pre-amp output arrangement. Is it DC block or servo or none?
The shorting plug is a standard RCA plug with a wire link soldered between the pin and the shield. Make up a pair of these and keep for future setting up and/or testing.
Yes thats exactly what I meant in my post about re-setting offset with the line stage connected. I had to do just that with my own KSA-50 and each channel was slightly different... didn't surprise me at all on a completely DC coupled amp. I'd be willing to bet that Krell also had some problems with this when they were introduced... Later Krells, I believe KSA-80 and on went to a servo controled DC offset circuit. Anyway... once you get it set its really stable with vitrually no drift at all.
Mark
Hi,
I did all your instructions (thank you for that) and what I've found is when you connect or short the input while the amp is ON, there was a -537mVdc in the output and the speaker will pull back then as the voltage return to zero the speaker also return to normal position.
And it will stable at 0V.
I hope that this is normal, as Mark says that there is a sligthly difference in each channel. The other channel has -34mVdc and the speaker will move very little then return to normal position as the voltage goes to zero.
Farley
I did all your instructions (thank you for that) and what I've found is when you connect or short the input while the amp is ON, there was a -537mVdc in the output and the speaker will pull back then as the voltage return to zero the speaker also return to normal position.
And it will stable at 0V.
I hope that this is normal, as Mark says that there is a sligthly difference in each channel. The other channel has -34mVdc and the speaker will move very little then return to normal position as the voltage goes to zero.
Farley
To my understanding it's improper procedure to connect/disconnect anything to your power-amp input(s) when it's powered-up and the speakers connected.
Any thump/click while connecting/disconnecting will be amplified at your speaker-outputs and possibly damage your speakers.
With kind regards,
Klaas
Any thump/click while connecting/disconnecting will be amplified at your speaker-outputs and possibly damage your speakers.
With kind regards,
Klaas
