Annoying Buzzing from HT-1

[MorningStar]

Hello everyone.

I own two HT-1R combos and I only use one of them. My friend came to jam and I gave him the other one, but when he plugged in, there was this annoying buzz in the sound when he was playing. but that's not just it, it also lacks clarity compared to the one I always use.
I've also noticed that when I put down the faulty combo on the floor the amp itself creates a buzzing sound!

Could anyone help me with this? is there a way to fix it?

Thanks in advance

[Adam-T]

Try changing the preamp valve --->

When I got mine used (it was my first valve amp since the 80s) a few months ago there was a very noticeable hum along with the sound especially on clean where you need the volume flat out (Could never have recorded with it) and put it down to it being a valve amp as valve amps I had in the 80s (Sound city stacks etc) always did it ...... when I got a HT5M combo it was clean as a whistle as is the non-metal head I have now so put it down to the HT1R being only 1W and flat out ....... I changed the Pre-amp valve to a UK NOS Mazda as everyone slagged off the stock Sovtek and the hum was gone , it`s silent even when flat out ..

A few notes
1:- mine was silent until a cable was plugged in - I didn`t realise at the time that the amp went into standby when no cables were plugged in , yours should be the same regardless of the noise
2:- mine was a mains HUM type sound not an earthing issue type buzz
3:- it will be louder on the floor as that accentuates certain frequencies
4:- a faulty / worn out preamp valve can definitely affect clarity, it only did to a degree on mine, it was enough to mask the brittle harsh nature of the stock speaker so the amp actually didn`t sound as smooth with the NOS British valve in than with the faulty Sovtek !! I need to change the speaker now - LOL - but it`s as clean as a whistle and there`s more ambience (I need less reverb)

[MorningStar]

Try changing the preamp valve --->

When I got mine used (it was my first valve amp since the 80s) a few months ago there was a very noticeable hum along with the sound especially on clean where you need the volume flat out (Could never have recorded with it) and put it down to it being a valve amp as valve amps I had in the 80s (Sound city stacks etc) always did it ...... when I got a HT5M combo it was clean as a whistle as is the non-metal head I have now so put it down to the HT1R being only 1W and flat out ....... I changed the Pre-amp valve to a UK NOS Mazda as everyone slagged off the stock Sovtek and the hum was gone , it`s silent even when flat out ..

A few notes
1:- mine was silent until a cable was plugged in - I didn`t realise at the time that the amp went into standby when no cables were plugged in , yours should be the same regardless of the noise
2:- mine was a mains HUM type sound not an earthing issue type buzz
3:- it will be louder on the floor as that accentuates certain frequencies
4:- a faulty / worn out preamp valve can definitely affect clarity, it only did to a degree on mine, it was enough to mask the brittle harsh nature of the stock speaker so the amp actually didn`t sound as smooth with the NOS British valve in than with the faulty Sovtek !! I need to change the speaker now - LOL - but it`s as clean as a whistle and there`s more ambience (I need less reverb)

Thank you so much for your comprehensive reply. the valve problem was also my first concern. but today I just discovered that the back cover is the culprit!

When I hold the back cover hardly the buzzing is gone! this is weird right?

[Adam-T]

The back cover is the chassis of the amp held down with loads of screws, is it an electricl buzz, if so then look for earthing issues (bad mains lead, loose sockets, loose PCB mounting screws inside) - or mechanical (loose screws alround inside and out......... BTW to take the "back off" (chassis out) you have to also remove the two handle screws closest to the knobs