Brand new Diezel VH4 Very Loud Hum in Standby

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Daigaijin

New member
Hi All,

I'd appreciate some guidance.

I've just received my brand new Diezel VH4. Before first powering up I visually checked all the valves and they seemed OK.

I noticed that with power on and in standby there is a very loud hum, like a transformer hum but way, louder.

This is my first VH4, but comparing it to other amps Engl E670SE and Friedman BE100DLX it is many times louder than them.

None of the tube check lights on the back are lit, it's the correct voltage for the UK and the noise is not really noticeable when taken off standby.

All the channels work, lights on the front panel light up etc All the tubes I can light up. I haven't checked the midi.

So without any specific frame of reference (my first VH4) the amp sounds OK. I'm using a decent power lead and speaker cable.

I've gone back to the nice people at Thomann and hope for a reply soon, but I may not know what they are talking about as I'm not even vaguely technical.

I've had a look about but can't find anything that's exactly the same issue and I'm hoping that someone here may have some insights.

So any help, opinion or suggestions would be most welcome.

Many thanks

PS Since posting I've tried different power leads, different sockets, turned the lights off and the a/c.

PPS I've reposted this from the tec section, hope that's OK.
 
My VH4 I think is the same. I picked it up last year and was very surprised by how loud the hum was, especially compare to the Herbert mk3 which is dead quiet. I checked with Peter and was told that "A certain mechanical hum on the power transformer is normal since 1992." I stopped worried about it and just play it as it sounds great and see no issues otherwise.
 
That would make sense. New gear so not sure what 'normal' is yet. I appreciate you taking the time to reply. Thanks
 
Daigaijin said:
That would make sense. New gear so not sure what 'normal' is yet. I appreciate you taking the time to reply. Thanks
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I totally get it, I was the same when it arrived and plugged it in to be met with a loud hum. As it was mentioned on the other thread, if the hum/noise is not coming from the speaker then I think you're probably fine and it's just the way these amps are.
 
punchy said:
I totally get it, I was the same when it arrived and plugged it in to be met with a loud hum. As it was mentioned on the other thread, if the hum/noise is not coming from the speaker then I think you're probably fine and it's just the way these amps are.
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I just checked, not coming out of the speakers when in standby. The tone of it changes when I go to RUN, tried all the channels (without input) maxing the volumes both channel and master and the transformer hum is either masked by the channel sounds or it fades considerably not sure which. Either way sounds like a characteristic of the amp and I can live with that. Top man, I'm much obliged.
 
Facing the amp: output transformer on the left and power transformer on the right (with the power tubes next to it). Pretty sure the hum is normal. It's a side effect of how the power transformer is constructed (sideways compared to many amps) and how it is directly attached to the chassis. Think of an engine mounted directly to the body of a car (without the rubber motor mounts that are normally between the motor and the chassis)- it would be fine, but very shakey, especially at idle.
I am wondering if putting a rubber gasket between the transformer and the chassis- during assembly- would help reduce the vibration/hum being transferred to the chassis and head case. I am almost certain it would help tremendously- the PT just needs something soft attached to it to dissipate that vibration. It would need to be rugged enough to hold up to the local heat put out by the power tubes as well.

The thing is once you are playing your amp, you're never going to hear it. If you do hear it somehow over your playing, THAT's a problem.
 
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