Hi guys,
to get some experience I have recently assembled an UCD 400 stereo kit from hypex exactly according the assembly instructions inside the original housing, which works pretty fine (sounds even more accurate compared to my ML431); some days ago there is some not very loud hum with a hiss in both speakers in a statistical manner with much less amplitude than the oscillation frequency which you can see on the output with the scope. This is only few seconds and disappears afterwards. First I thought that it may come from the preamp (ML380) which is connected symmetrical via XLR on both sides, I disconnected the XLRs at the amp but nothing changed. The speaker cables are pretty short (less than 1 meter 4mm2)
Does anybody have some ideas/hints/experience with this weird behaviour?
best regards
Dieter
to get some experience I have recently assembled an UCD 400 stereo kit from hypex exactly according the assembly instructions inside the original housing, which works pretty fine (sounds even more accurate compared to my ML431); some days ago there is some not very loud hum with a hiss in both speakers in a statistical manner with much less amplitude than the oscillation frequency which you can see on the output with the scope. This is only few seconds and disappears afterwards. First I thought that it may come from the preamp (ML380) which is connected symmetrical via XLR on both sides, I disconnected the XLRs at the amp but nothing changed. The speaker cables are pretty short (less than 1 meter 4mm2)
Does anybody have some ideas/hints/experience with this weird behaviour?
best regards
Dieter
Hello Habadudl,
Last week a friend of mine had a comparable problem, his (active) loudspeaker system started to produce hum.
After some trials we found that he had changed some extention cords. We took away the cord which apparently caused the situation and connected the system to a shorter cord. The hum did not return. After checking the cord seemed to be ok afterall. Probaby some systems suffer from using a series of extention cords. Keep the power connection as simple and as short as possible.
Good luck.
Rob.
Last week a friend of mine had a comparable problem, his (active) loudspeaker system started to produce hum.
After some trials we found that he had changed some extention cords. We took away the cord which apparently caused the situation and connected the system to a shorter cord. The hum did not return. After checking the cord seemed to be ok afterall. Probaby some systems suffer from using a series of extention cords. Keep the power connection as simple and as short as possible.
Good luck.
Rob.
Hi Rob,
thanks - my power cord (3*2,5mm2) is pretty short (about 1 meter) and shielded to the power outlet in the wall; I will check on what side the shield is grounded. Maybe the extension cord from your friend was not grounded properly?
best regards
Dieter
thanks - my power cord (3*2,5mm2) is pretty short (about 1 meter) and shielded to the power outlet in the wall; I will check on what side the shield is grounded. Maybe the extension cord from your friend was not grounded properly?
best regards
Dieter
Hallo Dieter,
Indeed not grounded properly and not shielded either, furthermore he used two in series of which the second one was of very poor quality.
I hope You can solve your problem, because I like the UCD 400HXR very much and it would be a waste if You could not make use of them anymore.
Maybe ask Hypex they have excellent service. I am using the Ucd’s for about 12 years now, before I had Zap pulse Se 2.1, but the Ucd’s sound much better.
So You will understand I have no problems with the Ucd’s, I use them with linear psu’s, a single 1kW toroid and 2*22.000uF RIFA Elcaps/ channel.
Best regards,
Rob.
Indeed not grounded properly and not shielded either, furthermore he used two in series of which the second one was of very poor quality.
I hope You can solve your problem, because I like the UCD 400HXR very much and it would be a waste if You could not make use of them anymore.
Maybe ask Hypex they have excellent service. I am using the Ucd’s for about 12 years now, before I had Zap pulse Se 2.1, but the Ucd’s sound much better.
So You will understand I have no problems with the Ucd’s, I use them with linear psu’s, a single 1kW toroid and 2*22.000uF RIFA Elcaps/ channel.
Best regards,
Rob.
Hi Rob,
after opening of the housing and carefully check everything some days ago I closed it again - and so far this hiss with hum seem to be gone; maybe a not perfectly done contact had been the cause. Nevertheless I will see if the problem disappeared finally.
best regards
Dieter
after opening of the housing and carefully check everything some days ago I closed it again - and so far this hiss with hum seem to be gone; maybe a not perfectly done contact had been the cause. Nevertheless I will see if the problem disappeared finally.
best regards
Dieter
Hi Dieter,
Good to read it's gone, hope You can enjoy the amplifier as much as i do.
Best regards,
Rob.
Good to read it's gone, hope You can enjoy the amplifier as much as i do.
Best regards,
Rob.
Hi Rob,
today this phenomenon occured again unfortunately, and it seems that this effect comes from ripple contol in the grid (with this system the electric power company switches loads like big water boilers etc). I also found out that a fluorescent tube which is on the same phase makes some noise in the speakers switching on or off.
Is the SMPS 400 A400 which is used in this kit so sensitive to noise coming from the power line? any ideas to solve the problem - I want to avoid an additional clean power supply.
best regards
Dieter
today this phenomenon occured again unfortunately, and it seems that this effect comes from ripple contol in the grid (with this system the electric power company switches loads like big water boilers etc). I also found out that a fluorescent tube which is on the same phase makes some noise in the speakers switching on or off.
Is the SMPS 400 A400 which is used in this kit so sensitive to noise coming from the power line? any ideas to solve the problem - I want to avoid an additional clean power supply.
best regards
Dieter
Hi Dieter,
My amp is using a linear PSU and it works well, besides we almost certain have a different energy supplier.
This possible problem of a SMPS dealing with poluted grid is new to me.
Maybe check the waveform on the grid with an oscilloscope? I recently checked our sinus waveform and its not very pretty.
Best regards,
Rob.
My amp is using a linear PSU and it works well, besides we almost certain have a different energy supplier.
This possible problem of a SMPS dealing with poluted grid is new to me.
Maybe check the waveform on the grid with an oscilloscope? I recently checked our sinus waveform and its not very pretty.
Best regards,
Rob.