Hello everybody,
i have a problem with my amp and i would like to have some opinion.
It is a unison research simply Italy, 12w class A tube, single ended.
It all started a few months ago when, by rehearsing, I realized that the left channel sounded less well and at a lower volume than the right and also emitted a slight hum. So I decided after several emails with the company, to send him in assistance to the unison in Treviso.
They replaced me with some components that they said were worn out and changed the valves because, as they said: "because of the way the amp was reduced" maybe my valves had been ruined (actually in the previous months they had strangely and mysteriously broken well two new el34 svetlana winged C that I had bought to have some fun). Expenditure on repairs only, excluding valves: 180euro.
However when I return from the company, I turn on the amp, I immediately notice that for the same position of the knob, the volume is higher and everything seems fine, until ... I disconnect the right channel and I hear the hum in the left there is still! I send an email to the company and they tell me it's very strange because it didn't happen to them and they even kept it on trial for a week. Then the pandemic broke out and therefore there was no follow-up to the thing.
I wanted to ask you if you have any idea what it can be: it is a hum, not a murmur, only in the left channel. You can also hear it at zero volume, it exits the tweeter and the midwoofer and begins a few seconds after the amplifier is turned on, as if it were due to a final valve. However, when the valves are exchanged, the problem remains on the left. I tried to disconnect all the sources, but the problem remains (on each source), I tried to short-circuit a rca input but nothing changes, to unplug the fridge, every household appliance or switching power supply, without success, to change power cables and power but nothing.
What can be?
Thanks to anyone who wants to contribute ...
i have a problem with my amp and i would like to have some opinion.
It is a unison research simply Italy, 12w class A tube, single ended.
It all started a few months ago when, by rehearsing, I realized that the left channel sounded less well and at a lower volume than the right and also emitted a slight hum. So I decided after several emails with the company, to send him in assistance to the unison in Treviso.
They replaced me with some components that they said were worn out and changed the valves because, as they said: "because of the way the amp was reduced" maybe my valves had been ruined (actually in the previous months they had strangely and mysteriously broken well two new el34 svetlana winged C that I had bought to have some fun). Expenditure on repairs only, excluding valves: 180euro.
However when I return from the company, I turn on the amp, I immediately notice that for the same position of the knob, the volume is higher and everything seems fine, until ... I disconnect the right channel and I hear the hum in the left there is still! I send an email to the company and they tell me it's very strange because it didn't happen to them and they even kept it on trial for a week. Then the pandemic broke out and therefore there was no follow-up to the thing.
I wanted to ask you if you have any idea what it can be: it is a hum, not a murmur, only in the left channel. You can also hear it at zero volume, it exits the tweeter and the midwoofer and begins a few seconds after the amplifier is turned on, as if it were due to a final valve. However, when the valves are exchanged, the problem remains on the left. I tried to disconnect all the sources, but the problem remains (on each source), I tried to short-circuit a rca input but nothing changes, to unplug the fridge, every household appliance or switching power supply, without success, to change power cables and power but nothing.
What can be?
Thanks to anyone who wants to contribute ...
Last edited:
You could open the amp and post some photos here. There could be something that shifted during shipping that's causing the issue.