Hi guys! I hope that somebody has much more knowledge than me about this problem. There must something that I am not doing wright obviously.
Every time I turn the amplifier off it makes sort pop, thumb or click noise.
How can I make it stop doing that?
This is not happening only with this one amplifier. Every single amplifier that I have made, had this problem. Sometimes it is really loud and scary 😕
Turning power on makes no noise because I have a delay for that but no matter what type of a relay I put, the noise is there every time i turn the power off.
Every time I turn the amplifier off it makes sort pop, thumb or click noise.
How can I make it stop doing that?
This is not happening only with this one amplifier. Every single amplifier that I have made, had this problem. Sometimes it is really loud and scary 😕
Turning power on makes no noise because I have a delay for that but no matter what type of a relay I put, the noise is there every time i turn the power off.
Do you use a start delaied speakers connection with relay?
The protection (delay) module must have an input directly from secondary (AC side) of the transformer and when it is detected "no AC voltage" when you switch off the amplifier, must switch off the relay. On this input the filtering shoud be as low as posible to not generate delay and to disconnect the speakers as fast as posible in case of power off.
I supose that here it is your problem.
The protection (delay) module must have an input directly from secondary (AC side) of the transformer and when it is detected "no AC voltage" when you switch off the amplifier, must switch off the relay. On this input the filtering shoud be as low as posible to not generate delay and to disconnect the speakers as fast as posible in case of power off.
I supose that here it is your problem.
Now that you mentioned it, I‚ll see if it is problem in the module. I thought that the modules are all the same 😉
The module has direct input from secondary from separate transformer, I think it is some 10-12 volts AC.
I‚ll make speaker soft start from another schematic and test it to see if it is working so to be sure if the fault is in the module.
The module has direct input from secondary from separate transformer, I think it is some 10-12 volts AC.
I‚ll make speaker soft start from another schematic and test it to see if it is working so to be sure if the fault is in the module.
Does the noise appear at the instant (to the microsecond 😀) that you turn the power off, or is it a fraction of a second or more after ? If the first then it can be the switch contacts arcing and sending a burst of RF energy in all directions. If the second, then its common on a lot of amps and best cured with a fast acting disconnect to the speakers.
Here's a simple one I made earlier,
http://www.diyaudio.com/forums/solid-state/224957-simple-universal-speaker-delay-using-triac.html
Here's a simple one I made earlier,
http://www.diyaudio.com/forums/solid-state/224957-simple-universal-speaker-delay-using-triac.html
Put a 1-10nF X-rated capacitor directly across the mains transformer primary. This will suppress the switch arcs which cause switch-off clicks.
A low frequency thump a few seconds after switching off is caused by the circuit closing down unevenly. You need a mute circuit to stop that.
A low frequency thump a few seconds after switching off is caused by the circuit closing down unevenly. You need a mute circuit to stop that.
Geminni, can you provide schematic used by you? And the component values too if not visible?
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The plop, bang or click comes instantly after the power switch is released.
This is the schematics
http://www3.telus.net/chemelec/Projects/M250/M250-DC_Protection-SCH.png
I will try that with a capacitor directly across the mains transformer. Now I have just remembered that I have saw some blue things or somtehing like that, in some amplifier that is soldered paralel to a switch. Not paralel to a transformer but paralel to a switch contacts so when it is in "off" position "ac" goes through that cap and when the switch is "on" position the cap is shorten. 😕
This is the schematics
http://www3.telus.net/chemelec/Projects/M250/M250-DC_Protection-SCH.png
I will try that with a capacitor directly across the mains transformer. Now I have just remembered that I have saw some blue things or somtehing like that, in some amplifier that is soldered paralel to a switch. Not paralel to a transformer but paralel to a switch contacts so when it is in "off" position "ac" goes through that cap and when the switch is "on" position the cap is shorten. 😕
Try switching the amp off from elsewhere such as at the wall socket, or even just pulling the plug out. See if it makes the same noise instantly.
From your description it appears to be switch related because the rails in the amp wouldn't have had time to decay to cause noise due to other causes.
From your description it appears to be switch related because the rails in the amp wouldn't have had time to decay to cause noise due to other causes.
Your DC offset protection circuit doesn't appear as though it will drop out instantly. The time constant of the 12volt supply to the relay plays a big part. Slow drop out is a major failing of many circuits.
A cap across the primary is better than a cap across the switch. Reasons:
1. it does the same job of suppressing arcs
2. when Off the cap is not subject to continuous AC voltage stress, so lasts longer
3. when Off there is no switch bypass to allow some mains current through to the transformer
1. it does the same job of suppressing arcs
2. when Off the cap is not subject to continuous AC voltage stress, so lasts longer
3. when Off there is no switch bypass to allow some mains current through to the transformer
Just to add a point
, the cap across the primary should by a X-rated cap, that is rated for mains use.
, the cap across the primary should by a X-rated cap, that is rated for mains use.
Just to add a point
Its a very good point. Even if you have an ordinary cap that says its good for 1000vdc/400vac DONT use it. They must be rated as CBS240 advises.
I didn't know about that x-rated caps. Is there a print on cap just like that "x" or something?
I have found some caps and here is the picture so you can tell me if I can use something like that.
I have found some caps and here is the picture so you can tell me if I can use something like that.
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That's an old cap (11/92). I wouldn't like to say 100% as todays requirements are strict.
BFC233610104 - VISHAY BC COMPONENTS - CAPACITOR, CLASS X1, 0.1UF | CPC From This Range
BFC233610104 - VISHAY BC COMPONENTS - CAPACITOR, CLASS X1, 0.1UF | CPC From This Range
I didn't knew that was a date 🙂 Thank's for that!
Can i use that one from my picture just for test? I'll by the new one if that 0,1uf stops switching noise.
Can i use that one from my picture just for test? I'll by the new one if that 0,1uf stops switching noise.
It should work. You'll also find suitably rated capacitors in dead PC power supplies. A 1Meg resistor across the terminals is also recommended to discharge the cap
An X-rated cap will say so; it may say X1 or X2. No X, means 'not X'. You can use a Y-rated cap instead, as these are even more reliable. Y caps tend to be smaller in value and may be more expensive.
Well, this is embarrassing. I have made a mistake about schematics. The speaker Dc protection in this amplifier is this schematics, it is from a project N-Mos amplifier.
The previous posted protection is from M-250 amplifier and it is working in my Quad405 box. Today I have tested both amplifiers and the conclusion is that the one in Quad405 is working without clicks and the one with N-mos schematics makes that noise. The Relays are the same type in all amplifiers. Difference is schematics for DC protection and the thing that in troubled amplifier I have also soft start for toroid transformer. Can that make that clicks noise when switching off?
Just to add that Dc protection has its own transformer in both amplifiers, it is not connected to main transformer.
The previous posted protection is from M-250 amplifier and it is working in my Quad405 box. Today I have tested both amplifiers and the conclusion is that the one in Quad405 is working without clicks and the one with N-mos schematics makes that noise. The Relays are the same type in all amplifiers. Difference is schematics for DC protection and the thing that in troubled amplifier I have also soft start for toroid transformer. Can that make that clicks noise when switching off?
Just to add that Dc protection has its own transformer in both amplifiers, it is not connected to main transformer.
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