AC10 C1 odd buzz / harmonic

[SJB]

My AC10 is producing either a distortion buzz or odd harmonic when playing the 1st and 2nd strings from the 11 fret upwards - when both strings are picked.
If one is sounding and the other picked the noise is present.
Individually the notes are clean.
Its been like this from New - though it was an issue with the G3 - but now I have a new guitar its the same with both guitars plugged directly into the amp.

Yesterday I replaced the EL84's - one failed with horrific microphony. For some time I was thinking that I would change the valves and this issue would resolve.
I have not changed the ECC83's

So if anyone else has an AC10 C1 - could you check if picking the 1st and 2nd strings 11th fret upwards - one after the other or together - you have this effect.

Thanks

SJB

[JimN]

Have you tried that guitar on a different amplifier?

It sounds to me like an issue with frets or the strings. I hope it's just the strings.

[SJB]

Thanks for the post Jim.
I have now tried my Ibanez guitar - same issue on all pickups. So we have the same issue on three guitars - so its the amp.

I made a dummy load - used headphones - and all is clear as a bell.

So it's down to microphony (did I spell that correctly) or the speaker. Or something loose.
I will check now with another AC10 (new one) which should be available for me to try on Thursday.

It's not an issue when playing live - but it is an issue recording.

[Hunt1967]

Did you find the problem, I’ve just got the AC10 and have a RAT dummy load box
Was it the dummy load that caused the problem I don’t want to use it if it can cause the amp problems
Mick

[SJB]

Mick,

Using a dummy load - providing its the correct impedance won't do any damage. I don't think the odd buzz / harmonic is present with direct recording /dummy load.

With respect to the odd buzz / harmonic I noted when someone purchased a new AC10 - it has the same issue.
This time the guitar was a Telecaster.
My amp has been used at high volume - keeping pace with AC15's and loud drummer.

The issue arises even on very low volume. This is a class A amplifier so low volume should be OK.

I have recently moved and the house is in the process of being adjusted as it were. So I can't fully check the situation now.

The house move from Southampton to Wales - has taken my time - so I have not looked at this for some time.
I will get to the bottom of this at some time - but when playing loud at the clubs - it's not an issue.

Will follow up as soon as I can.

By the way I have taken JimN comment on board - I have dampened the tremolo springs by putting foam inside them.
I am using Fender Bullets 9's. I have to be careful as I have had Carpal Tunnel ops on both hands.

Stu